CN1747774A - Method and apparatus for separating and recovering carbon dioxide - Google Patents

Abstract

A method for separating and recovering carbon dioxide from a by-produced gas and the like generated in an ironworks by the chemical absorption method, characterized in that it comprises utilizing the low quality waste heat generated in an ironworks in the process wherein carbon dioxide is absorbed by a chemical absorption fluid from said gas and then the carbon dioxide is separated by heating the chemical absorption fluid.

Description

Carbon dioxide separation and recovery method and device

technical field

The present invention relates to a method and device for separating and recovering carbon dioxide (hereinafter simply referred to as CO ₂ ). More specifically, it relates to such a method and device for separating and recovering CO ₂ . When using a chemical absorption method to separate and recover CO ₂ , the CO ₂ -containing gas supplied from a plurality of CO ₂ (generating) sources is first absorbed by an absorption medium. CO ₂ in the CO 2 , and then the absorption medium that completes the CO ₂ absorption is collected and regenerated in one place, so that the efficiency of the equipment can be improved, and the exhaust heat that is in a different place from the CO ₂ (generating) source can be used.

Furthermore, the present invention relates _to a method for separating and recovering _CO that utilizes or is flexibly applied to low-grade ( Low temperature) heat exhaust, in which CO ₂ comes from by-product gas (unburned gas), its combustion exhaust gas, or its modified process gas and other CO ₂ -containing gases.

Background technique

In recent years, countermeasures against global warming have been vigorously promoted, such as the promotion of energy saving in the manufacturing stage and the utilization stage, the utilization of new energy sources such as solar energy, wind energy, and biofuels, and the conversion of low-environmental energy such as natural gas. Load fuel conversion, etc.

On the other hand, research aimed at separating, recovering, sequestering, and immobilizing the generated greenhouse gas (carbon dioxide) is being vigorously advanced. For example, a plan to separate and recover carbon dioxide from the combustion exhaust gas of a thermal power plant by using chemical absorption is proposed (for example, refer to Kiyohara Masaoka, Test of _CO2 Recovery from Power Generation Boiler Exhaust, Energy and Resources, Energy and Resources Society, 1993, Volume 14, Issue 1, p.91-97). According to this scheme, although it varies with the conditions, the separation and recovery of carbon dioxide can reach 90%.

However, when carbon dioxide is separated and recovered from the combustion exhaust gas of such a thermal power plant (boiler exhaust gas for power generation) by chemical absorption, the concentration of carbon dioxide contained in the combustion exhaust gas of the thermal power plant is as low as several volume % to more than ten % by volume, so the equipment used in the chemical absorption method will become very large. In addition, when the carbon dioxide is separated and recovered by the chemical absorption method, thermal energy becomes a factor that plays a decisive role in terms of operating costs.

However, thermal power plants optimized for the single process of power generation do not have the ability to flexibly apply heat removal by chemical absorption. Therefore, the following methods have to be adopted, either installing new heat generation equipment, or using Steam used for power generation, which will lead to a reduction in power generation efficiency.

On the other hand, when the separated and recovered carbon dioxide is sequestered in the ground or in the ocean, there is no economic advantage (only increased cost), even if it is intended to be effectively used as a chemical raw material, etc., the domestic market in Japan is small and has basically There are structural problems such as insufficient economic driving force to meet the needs in reality.

Contents of the invention

Therefore, an object of the present invention is to provide a technique for efficiently and inexpensively separating and recovering carbon dioxide emitted from a steel plant, one of large-scale carbon dioxide generation sources, with smaller-scale equipment than thermal power plants.

Another object of the present invention is to provide a technique for efficiently and inexpensively separating and recovering carbon dioxide from a carbon dioxide generating source by combining a carbon dioxide generating source and an absorbing liquid regeneration heat source located in different places.

Then, in order to achieve the above object, the inventors of the present invention have intensively studied the technology of separating and recovering the carbon dioxide emitted from the large-scale carbon dioxide generation source, and as a result, it has been found that the blast furnace gas and other by-products such as blast furnace gas, which are the large-scale carbon dioxide generation source, are produced. The raw gas (unburned gas) is different from the combustion exhaust gas of burning fossil fuels in the air, and the ratio (concentration) of carbon dioxide is as high as 20 to 30 percent.

From this result, it is known that when the carbon dioxide is separated and recovered by the chemical absorption method, the equipment for separating and recovering the same amount of carbon dioxide can be remarkably downsized as compared with the case of a thermal power plant.

In addition, iron and steel plants are composed of many processes such as blast furnaces, converters, sintering, coke ovens, heating furnaces, casting, and rolling. Various improvements have been made for energy saving. It can be considered that only unused room for low-grade thermal energy.

However, it has also been known that the heating of the chemical absorption liquid is the factor that plays a decisive role in the operation cost. If this energy is used or utilized in the heating of the chemical absorption liquid, the operation cost of the chemical absorption method can be greatly reduced. .

Furthermore, it is known that the above-mentioned by-product gas can be used as fuel gas in the ironmaking process, and by extracting carbon dioxide during the process, the energy density of the gas can be increased, and the thermal efficiency of the subsequent process can be improved.

Furthermore, it is also known that the combustion gas after combustion and utilization of by-product gases such as converter gas in iron and steel plants contains CO ₂ at a ratio of as high as 30 %, and it is possible to further reduce the size of the equipment for separating and recovering carbon dioxide.

Based on the above findings, the present inventors have completed the present invention.

Furthermore, the present inventors tried to analyze the cost of separation and recovery of carbon dioxide by chemical absorption, and came to the conclusion that the biggest cost factor is the heat source for regenerating the carbon dioxide absorption medium, and its high efficiency is crucial for achieving effective and inexpensive separation. The purpose of recovering carbon dioxide is effective.

That is, the present invention can be achieved by the method and apparatus for separating and recovering carbon dioxide described in (1) to (22) below.

(1) A method for separating and recovering carbon dioxide from the by-product gas produced by a steel plant by chemical absorption, characterized in that: after absorbing carbon dioxide from the gas with a chemical absorption liquid, heating the chemical absorption liquid to separate the carbon dioxide In the process, the low-grade exhaust heat of 500 °C or below generated by the steel plant is used or utilized.

(2) A method for separating and recovering carbon dioxide from the combustion exhaust of by-product gas produced by a steel plant by chemical absorption, characterized in that: after absorbing carbon dioxide from the gas with a chemical absorption liquid, the chemical absorption liquid is heated In the process of separating carbon dioxide, low-grade exhaust heat of 500°C or below generated by iron and steel plants is used or utilized.

(3) A method for separating and recovering carbon dioxide from the process gas produced by the upgrading process by chemical absorption, wherein the upgrading process is used to produce hydrogen from the by-product gas produced by the iron and steel plant, and the method is characterized in that : After absorbing carbon dioxide from the gas with a chemical absorption liquid, in the process of heating the chemical absorption liquid to separate the carbon dioxide, the low-grade exhaust heat of 500°C or below generated by the steel plant is utilized or utilized.

(4) The method for separating and recovering carbon dioxide according to any one of the above (1) to (3), wherein carbon dioxide in the above-mentioned by-product gas, combustion exhaust gas, or process gas of the above-mentioned chemical absorption method is supplied The concentration is 15% by volume or more.

(5) The method for separating and recovering carbon dioxide according to any one of (1) to (4) above, wherein the by-product gas is at least one of blast furnace gas, coke oven gas, and converter gas.

(6) The method for separating and recovering carbon dioxide according to any one of the above (1) to (5), characterized in that all or part of the heat necessary for the regeneration of the chemical absorption liquid is exhausted heat generated by a steel plant. .

(7) The method for separating and recovering carbon dioxide according to any one of the above (1) to (6), characterized in that: according to the characteristics of the above-mentioned chemical absorption liquid, for the regeneration of the chemical absorption liquid, the carbon dioxide produced by the steel plant is utilized in multiple stages. proper heat removal.

(8) The method for separating and recovering carbon dioxide according to any one of the above (1) to (7), characterized in that: for the regeneration of the above-mentioned chemical absorption liquid, the exhaust heat generated by the steel plant is utilized as much as possible or fully utilized, and at the same time Use factory steam.

(9) A device for separating and recovering carbon dioxide from a carbon dioxide generation source, characterized in that the device comprises:

Carbon dioxide absorbing equipment: for absorbing carbon dioxide from a gas containing carbon dioxide supplied by a carbon dioxide generating source using a carbon dioxide absorbing medium;

Absorption medium regeneration equipment: used to separate carbon dioxide from the absorption medium that has absorbed carbon dioxide by using the heat source for absorption medium regeneration to regenerate the absorption medium;

Carbon dioxide absorbing medium: circulates between the two devices as a transport medium for carbon dioxide; and

Outgoing piping and return piping: used to transport carbon dioxide absorption medium;

Wherein, the above-mentioned carbon dioxide absorption equipment is installed near the carbon dioxide generation source, and the above-mentioned absorption medium regeneration equipment is installed in a place different from the place where the carbon dioxide generation source is located.

(10) The separation and recovery device for carbon dioxide according to the above (9), characterized in that: the distance A between the carbon dioxide generation source and the carbon dioxide absorption equipment, the distance B between the absorption medium regeneration equipment and the heat source for absorption medium regeneration , and the distance C between the carbon dioxide absorption equipment and the absorption medium regeneration equipment satisfies the relational expressions of A<C and B<C.

(11) The carbon dioxide separation and recovery device according to the above (9) or (10), characterized in that: the piping distance X for supplying the gas containing carbon dioxide from the carbon dioxide generation source to the carbon dioxide absorption equipment, the carbon dioxide absorption medium The sending piping distance Y, the return piping distance Z, and the piping distance W for supplying heat from the heat source for absorption medium regeneration to the absorption medium regeneration equipment satisfy the relational expression of 2X<(Y+Z) and (X+W) <(Y+Z) at least one relational expression among the relational expressions.

(12) The separation and recovery device for carbon dioxide according to any one of the above (9) to (11), characterized in that the above-mentioned absorption medium regeneration equipment is installed near the exhaust heat source of the process used as the heat source for absorption medium regeneration .

(13) The carbon dioxide separation and recovery device according to any one of (9) to (12) above, characterized in that exhaust heat from the process is used as part or all of the heat source for regeneration of the absorption liquid.

(14) The separation and recovery device for carbon dioxide according to any one of the above (9) to (13), characterized in that: the composition of the separation and recovery device includes the above-mentioned one or more sets of carbon dioxide absorption equipment and one or more sets Set of absorption liquid regeneration equipment.

(15) The carbon dioxide separation and recovery device according to any one of the above (9) to (14), characterized in that: as a part or all of the heat source for regeneration of the absorption liquid, multi-stage processes using different temperature levels Exhaust heat.

(16) A method for separating and recovering carbon dioxide from a carbon dioxide generating source, characterized in that: a carbon dioxide absorbing device arranged close to the carbon dioxide generating source is used, and a carbon dioxide absorbing medium is used to absorb carbon dioxide from the carbon dioxide-containing gas supplied by the carbon dioxide generating source, Thereafter, the carbon dioxide absorbing medium is heated by a heat source for absorbing liquid regeneration, and carbon dioxide is separated using an absorbing liquid regeneration facility located in a different location from the carbon dioxide generating source.

(17) The separation and recovery method of carbon dioxide according to the above (16), characterized in that: the distance A between the above-mentioned carbon dioxide generation source and the carbon dioxide absorption equipment, the distance between the absorption medium regeneration equipment and the heat source for absorption medium regeneration B, and the distance C between the carbon dioxide absorption equipment and the absorption medium regeneration equipment satisfies the relational expressions of A<C and B<C.

(18) The method for separating and recovering carbon dioxide according to the above (16) or (17), characterized in that: the piping distance X for supplying the gas containing carbon dioxide from the carbon dioxide generating source to the carbon dioxide absorbing equipment, the carbon dioxide absorbing medium The sending piping distance Y, the return piping distance Z, and the piping distance W for supplying heat from the heat source for absorption medium regeneration to the absorption medium regeneration equipment satisfy the relational expression of 2X<(Y+Z) and (X+W) <(Y+Z) at least one relational expression among the relational expressions.

(19) The method for separating and recovering carbon dioxide according to any one of the above (16) to (18), characterized in that: the above-mentioned absorption medium regeneration equipment is arranged near the exhaust heat source of the process used as the heat source for absorption medium regeneration .

(20) The method for separating and recovering carbon dioxide according to any one of (16) to (19) above, characterized in that process exhaust heat is used as part or all of the heat source for regeneration of the absorption liquid.

(21) The separation and recovery method of carbon dioxide according to any one of the above (16) to (20), characterized in that: the separation and recovery method uses the above-mentioned one or more sets of carbon dioxide absorption equipment and one or more sets of absorption Liquid regeneration equipment.

(22) The method for separating and recovering carbon dioxide according to any one of (16) to (21) above, characterized in that: as a part or all of the heat source for regeneration of the absorption liquid, multi-stage processes using different temperature levels Exhaust heat.

Description of drawings

Figure 1 is a process schematic diagram for separating and recovering carbon dioxide from raw gas containing carbon dioxide by chemical absorption.

Fig. 2 is a schematic diagram showing a process for separating and recovering carbon dioxide from raw material gas generated in a steel plant by chemical absorption, wherein exhaust heat generated in the steel plant is used as all of the heat necessary for regeneration of the chemical absorption liquid.

Fig. 3 is a schematic diagram showing a process for separating and recovering carbon dioxide from raw gas produced in a steel plant by chemical absorption, wherein appropriate gas produced in a steel plant is utilized in multiple stages for the regeneration of the chemical absorption liquid according to the characteristics of the chemical absorption liquid Exhaust heat.

Fig. 4 is a schematic diagram showing a process for separating and recovering carbon dioxide from raw material gas generated in a steel plant by chemical absorption, in which waste heat generated in the steel plant is utilized for regeneration of the chemical absorption liquid, and factory steam is also utilized.

Fig. 5 is a schematic diagram showing a typical device according to the second embodiment of the present invention, and is a diagram showing a device (process) for separating and recovering carbon dioxide by combining a carbon dioxide generating source and an absorbing liquid regeneration heat source in different places.

6 is a schematic view showing another typical device according to the second embodiment of the present invention, and is a diagram showing a device (process) for separating and recovering carbon dioxide by combining a carbon dioxide generating source and an absorbing liquid regeneration heat source in different places.

Fig. 7 is a schematic diagram showing a third representative device according to the second embodiment of the present invention, showing a device (process) for separating and recovering carbon dioxide by combining a carbon dioxide generating source and an absorbing liquid regeneration heat source in different places picture.

Fig. 8 is a schematic diagram showing a fourth representative device of the second embodiment of the present invention, and is a schematic diagram showing a device (process) for separating and recovering carbon dioxide by combining a carbon dioxide generation source and an absorption liquid regeneration heat source in different places picture.

Fig. 9 is a schematic diagram showing a fifth representative device of the second embodiment of the present invention, showing a device (process) for separating and recovering carbon dioxide by combining a carbon dioxide generating source and an absorbing liquid regeneration heat source in different places picture.

Fig. 10 is a schematic view showing an apparatus used in Specific Example 1 of the second embodiment of the present invention, and is a diagram showing an apparatus (process) for separating and recovering carbon dioxide by combining a carbon dioxide generation source and an absorption liquid regeneration heat source in different places .

Fig. 11 is a schematic view showing an apparatus used in Specific Example 2 of the second embodiment of the present invention, and is a diagram showing an apparatus (process) for separating and recovering carbon dioxide by combining a carbon dioxide generation source and an absorption liquid regeneration heat source in different places .

Fig. 12 is a schematic diagram showing an apparatus used in Specific Example 3 of the second embodiment of the present invention, and is a diagram showing an apparatus (process) for separating and recovering carbon dioxide by combining a carbon dioxide generation source and an absorption liquid regeneration heat source in different places .

Fig. 13 is a schematic view showing an apparatus used in Specific Example 4 of the second embodiment of the present invention, and is a diagram showing an apparatus (process) for separating and recovering carbon dioxide by combining a carbon dioxide generation source and an absorption liquid regeneration heat source in different places .

Fig. 14 is a schematic diagram showing an apparatus used in Specific Example 5 of the second embodiment of the present invention, and is a diagram showing an apparatus (process) for separating and recovering carbon dioxide by combining a carbon dioxide generation source and an absorption liquid regeneration heat source in different places .

Detailed ways

Specific embodiments (or examples) are listed below to illustrate the present invention together with each requirement. Needless to say, the present invention should not be limited to these embodiments.

The first embodiment of the present invention is a method for separating and recovering carbon dioxide from the raw material gas produced by the iron and steel plant by chemical absorption, characterized in that: as the raw material gas, it is selected from the by-product gas produced by the iron and steel plant, the by-product At least one of gas combustion exhaust gas and process gas produced in the reforming process, wherein the reforming process is used to produce hydrogen from the by-product gas, and the chemical absorption liquid is used to extract hydrogen from the After carbon dioxide is absorbed in the raw material gas, in the process of heating the chemical absorption liquid to separate the carbon dioxide, the low-grade exhaust heat of 500°C or below generated by the steel factory is used or utilized.

(Factories to which the separation and recovery method of this embodiment may be applicable)

The separation and recovery method of this embodiment may be applicable to plants, for example, as long as it is a steel plant that can generate by-product gas from blast furnaces, converters, coke ovens, etc., and may supply low-grade exhaust heat at or below 500 ° C, there is nothing wrong with it. special restrictions.

(raw gas)

The raw material gas used in the separation and recovery method of this embodiment may be by-product gas (unburned gas) produced in iron and steel plants. Although it varies depending on the structure of the steel plant, taking an integrated steelmaking plant as an example, the raw material gases include blast furnace gas (BFG), coke oven gas (COG), and converter gas ( LDG), in addition to this, also includes gas (process gas) generated in the process (process) of reforming by-product gases such as COG and LDG for the purpose of producing hydrogen.

One of these by-product gases may be used alone, or two or more of them may be used in a mixed state. In addition, the separation and recovery method of this embodiment may use the combustion exhaust gas of the above-mentioned by-product gas as a raw material gas, and may be used for the separation and recovery of carbon dioxide.

When these raw materials gases (by-product gases produced by iron and steel plants or their combustion exhaust gas) can be used as high-grade exhaust heat, then in the present invention, these gases can be used after the utilization of high-grade exhaust heat is completed. It is used because the temperature when absorbing carbon dioxide by the chemical absorption method can be a temperature near normal temperature.

One of these raw material gases may be supplied to the separation and recovery of carbon dioxide alone, or two or more types may be mixed and supplied to the separation and recovery of carbon dioxide. In addition to the mixed form of by-product gases and the mixed form of combustion exhaust gases of by-generated gases among the two or more kinds of mixed forms, it also includes the mixed form of combustion exhaust gases of by-generated gases and by-generated gases form.

In these raw material gases, the ratio of carbon dioxide in BFG is as high as 20 percent, and as other fuel components, the content of hydrogen is several percent, and the content of carbon monoxide is 20 percent. COG is rich in hydrogen and methane suitable for use as fuel gas, and the concentration of carbon dioxide in the exhaust gas after combustion (also called combustion exhaust gas) reaches several percent.

On the other hand, LDG contains about 10% of carbon dioxide and about 70% of carbon monoxide, and the concentration of carbon dioxide in the exhaust gas after combustion (combustion exhaust gas) is as high as about 30%.

Therefore, it is preferable to use BFG having a higher carbon dioxide ratio than that of a thermal power plant, BFG combustion exhaust, COG combustion exhaust, LDG combustion exhaust, and a mixed gas of these gases and other gases as the raw gas.

In addition, gas generated in the process of reforming COG and LDG to produce hydrogen as described later is also suitable.

Specifically, the ratio (concentration) of carbon dioxide in raw material gases generated from these iron and steel plants is 15% by volume or more, preferably 18% by volume or more, more preferably 20% by volume or more, still more preferably 22% by volume or more, particularly preferably 25% by volume or more.

When the carbon dioxide is separated and recovered from the gas with a high carbon dioxide ratio by means of chemical absorption, etc., the combustion exhaust gas with a low carbon dioxide concentration of the thermal power plant (about 8% in the thermal power plant of natural gas, and about 8% in the thermal power plant of coal) About 12%) compared to the case of using the raw material gas, the scale of the equipment can be greatly reduced (for example, compared with the case of separating and recovering carbon dioxide from the combustion exhaust gas with a low carbon dioxide concentration in a coal-fired power plant, in In the case of using BFG from a steel plant as raw gas, equipment costs may be reduced by about 30%.)

(Separation and recovery process of carbon dioxide)

In the separation and recovery method of this embodiment, the carbon dioxide is separated and recovered from the raw gas by means of a chemical absorption method. Furthermore, as a countermeasure against global warming, when carbon dioxide is separated and recovered from iron and steel plants, which are large-scale sources of carbon dioxide emissions, large-scale facilities capable of separating and recovering 1 million tons/year are required. In this case, the most widely developed and popular separation and recovery method of carbon dioxide is the chemical absorption method, which is also selected in the present invention.

The process principle of the chemical absorption method is illustrated below using the accompanying drawings. Fig. 1 is a schematic diagram showing a process for separating and recovering carbon dioxide from raw gas containing carbon dioxide by chemical absorption.

As shown in Figure 1, the chemical absorption method is a method in which the chemical absorption liquid is circulated between the absorption tower 1 and the regeneration tower 7, that is, the chemical absorption liquid such as amines is used, and the carbon dioxide absorption equipment is used as the carbon dioxide absorption equipment. In the reaction tower called the absorption tower 1, the raw material gas 3 containing carbon dioxide is brought into contact with the chemical absorption liquid 5 as the carbon dioxide absorption medium at about 50°C. After the chemical absorption liquid absorbs carbon dioxide, the liquid is sent to the In the regeneration tower 7 as the absorption liquid regeneration equipment, use the heating medium 9 as the heat source for the absorption liquid regeneration to heat it to about 120 ° C, and then the regeneration tower 7 separates and recovers carbon dioxide from the chemical absorption liquid, and the regenerated chemical absorption The liquid is returned to the absorption tower 1 through the return pipe 8.

Among the above-mentioned chemical absorption liquids, conventionally known solutions such as aqueous solutions containing amines and the like can be suitably used, and are not particularly limited to specific solutions.

In the separation and recovery method of this embodiment, the thermal energy necessary for the heating of the above-mentioned regeneration tower is the cause that determines the operating cost of the separation and recovery method. Therefore, in the separation and recovery method of this embodiment, low-grade exhaust heat of 500° C. or lower, preferably 400° C. or lower, generated by a steel plant is used or utilized as a heat source for absorption liquid regeneration.

That is to say, the separation and recovery method of the present embodiment utilizes or utilizes low-grade thermal energy that is difficult to utilize in the ironmaking process (even in low-grade thermal energy, it is also preferable to utilize or utilize high-temperature thermal energy as much as possible), therefore, it can It is not necessary to install thermal energy generating equipment to generate heating steam (heating medium 9 ), or to use steam used in power generation, like a thermal power plant.

Therefore, the use of chemical absorption can greatly reduce the cost of separation and recovery of carbon dioxide. In addition, as described above, since the concentration of carbon dioxide in the raw material gas is high, not only can the equipment be made compact, but also the amount of public facilities (electricity and water) required for the equipment can be reduced, And can further reduce operating costs.

Here, the reason why the low-grade exhaust heat generated by iron and steel plants used or utilized in the process of separating carbon dioxide is set at 500°C or less is based on the following reasons:

In other words, the exhaust heat exceeding 500°C is currently used by steel plants as high-grade exhaust heat. In the case of using this exhaust heat, it is different from the case of using (converting) steam for power generation in a thermal power plant. Same, or lead to the reduction of production efficiency, or need to set up new heat source generating equipment to supplement the conversion part, therefore, it is difficult to achieve the purpose of separating and recovering carbon dioxide cheaply.

However, when the low-grade exhaust heat of 500°C or below generated in iron and steel plants is used or utilized in the process of separating carbon dioxide, for example, a part of high-grade exhaust heat slightly exceeding 500°C is used at the same time to the extent that it does not affect the ironmaking process. Heat and combustion heat of fuel, this situation is also included in the technical scope of the present invention.

That is to say, the separation and recovery method of this embodiment certainly cannot be narrowly interpreted as: in the process of separating carbon dioxide, only the low-grade exhaust heat at or below 500°C produced by the iron and steel plant can be utilized or utilized.

The separation and recovery method described above can also utilize high-grade exhaust heat exceeding 500° C. and combustion heat of fuel without departing from the purpose of the present invention.

Examples of low-grade exhaust heat at 500°C or below in iron and steel plants include exhaust heat from sintered product coolers (approx. 230°C), sintering main exhaust gas (about 180°C), blast furnace slag water quenching water (about 90°C) and other low-grade heat energy that are difficult to use in ironmaking processes, but the present invention should not be limited to these.

In the current iron and steel plant, in order to reform the by-product gas COG and LDG into hydrogen-rich gas through water steam, high-purity hydrogen is recovered by using steam reforming equipment combined with oxygen combustion, and at the same time, the exhaust gas after hydrogen recovery is The utilization forms of these gases are more complete and complex, such as using them in converters in ironworks, etc.

Therefore, low-grade exhaust heat generated by incorporating equipment in a steel plant (steel plant or process) is also included in the low-grade exhaust heat of the separation recovery method of this embodiment. For example, it is preferable to use or utilize low-grade exhaust heat from the exhaust heat temperature of the sintered product cooler or lower. Exhaust heat exceeding the exhaust heat temperature (approximately 350°C) of the sintered product cooler is used effectively as a high-grade heat source in steelworks where current energy recovery technology is very advanced, although it depends on the steelworks configuration.

In addition, regarding the exhaust heat temperature, the reason why no specific temperature (value) is specified is because, depending on the setting conditions of the sintered product cooler, the exhaust heat from the sintered product cooler is transported to the CO Due to the distance of the process (or equipment) and the change of the outside air temperature, there will be some changes in the temperature when it is used or utilized in the process of separating and recovering carbon dioxide by chemical absorption.

More preferably, steam heating is performed by utilizing exhaust heat whose temperature is higher than the heating temperature (about 120° C.) of the chemical absorption liquid in the regeneration tower as much as possible. This is because the greater the temperature difference between the chemical absorption liquid and the exhaust heat, the smaller the equipment required for heat exchange may be, which in turn can reduce the cost of separation and recovery of CO ₂ .

In addition, the reason why low-grade exhaust heat such as "use or utilization" is stipulated is that low-grade exhaust heat can be directly used as the heating medium (thermal energy) used for heating the regeneration tower, and it can also be maintained at a predetermined temperature during heating. Aspects use a heating medium (eg, steam, etc.).

The former (direct utilization) is preferable in terms of simple device configuration and less heat loss; the latter (flexible utilization) is preferable in terms of easy control of maintaining the chemical absorption liquid in the regeneration tower at a constant temperature .

When the heating medium passes through the low-grade heat exhaust, corrosion and impurities in the piping are caused by corrosion components and impurities contained in the low-grade heat exhaust (drainage or exhaust). In order not to reduce the heat transfer rate, it is preferable to remove these corrosive components and impurities in advance. Impurities.

In addition, in the separation and recovery method of this embodiment, the above-mentioned low-grade exhaust heat (heat energy) can be used or utilized separately (as a single exhaust heat), or two or more low-grade exhaust heat can be used or utilized together. hot. When two or more types of exhaust heat are used in combination to heat the heating medium to a predetermined temperature, it is also possible to heat the heating medium in such a manner that the temperature of the exhaust heat is gradually increased starting from the exhaust heat with a lower temperature. At this time, if the final heat energy is insufficient, fuel can also be used for combustion.

That is to say, in the separation and recovery method of this embodiment, it is not necessarily limited to the use or utilization of low-grade exhaust heat in the process of separating and recovering carbon dioxide by chemical absorption. In addition to the consumption in the iron factory, A part of fuel gas sold as city gas or the like may also be used as auxiliary fuel.

Such an embodiment will be briefly described below using the drawings. 2 to 4 shown below are denoted by the same reference numerals as those in FIG. 1 and devices similar to those in FIGS. 2 to 3 .

Fig. 2 is a schematic diagram showing a process for separating and recovering carbon dioxide by chemical absorption from raw material gas (Fig. 2 is an example of by-product gas) produced in a steel plant, wherein all of the heat necessary for the regeneration of the chemical absorption liquid (or part), using the exhaust heat generated by steel mills.

In the embodiment shown in FIG. 2 , a chemical absorption liquid 5 such as amines is used, and the by-product gas 3 of the raw material gas containing carbon dioxide and the chemical absorption liquid 5 are kept at a temperature near normal temperature (for example, about 50° C.) in the absorption tower 1. After the chemical absorption liquid 5 absorbs carbon dioxide, the liquid is sent to the regeneration tower 7, and when the heating medium 9 is used to heat to a predetermined regeneration temperature (for example, about 120°C), it is necessary for the regeneration of the chemical absorption heat 5 All of the heat generated by the steel plant is utilized or fully utilized with low-grade exhaust heat at 500°C or below (such as exhaust heat from sintered product coolers, etc.) to separate and recover carbon dioxide 11 from chemical absorption liquid separation.

The above-mentioned low-grade exhaust heat can be used to heat the heating medium 9 such as steam as mentioned above, or can be directly used as the heating medium 9, and the form of its utilization or utilization is not particularly limited.

In the absorption tower 1, after the chemical absorption solution 5 absorbs carbon dioxide, the by-product gas 13 is returned to the by-product gas pipe 15, and is utilized as fuel gas or the like in a subsequent process. In addition, the chemical absorption liquid from which the heated carbon dioxide was extracted in the regeneration tower 7 is returned to the absorption tower 1 as the regeneration absorption liquid 5'.

In addition, in this embodiment, as all the heat necessary for the regeneration of the chemical absorption liquid, an example of utilizing or utilizing the low-grade exhaust heat of 500°C or below generated in a steel plant is shown, and the regeneration of the chemical absorption liquid An example in which a part of the necessary heat is utilized is illustrated in FIG. 4 .

Next, in the embodiment shown in FIG. 3 , the chemical absorption liquid 5 such as amines is used, and the by-product gas 3 of the raw material gas containing carbon dioxide and the chemical absorption liquid 5 are kept at a temperature near normal temperature (for example, about 50° C.) in the absorption tower 1. In contact with each other, after the chemical absorption liquid absorbs carbon dioxide, the liquid is sent to the regeneration tower 7, and when the heating medium 9 is used to heat to a predetermined regeneration temperature (for example, about 120 ° C), according to the characteristics of the chemical absorption liquid, in order to chemical absorption Regeneration of liquid and multi-stage (3 stages in Fig. 3) start from low-temperature exhaust heat and use the appropriate low-grade exhaust heat of 500 °C or below generated by the steel plant in a manner of increasing exhaust heat temperature.

That is to say, in the embodiment shown in Figure 3, the low-grade waste heat with the lowest temperature (for example, water quenching water (about 90°C) for blast furnace slag, etc.), the low-grade heat waste with the second lowest temperature ( For example, sintering main exhaust gas (about 280°C), etc.), and low-grade exhaust heat with the highest temperature (for example, exhaust heat of sintered product cooler (about 350°C), etc.), so as to separate and recover carbon dioxide from the chemical absorption liquid11 .

As mentioned above, the above three kinds of low-grade exhaust heat can be utilized sequentially for heating the heating medium 9 such as heating steam, or can be utilized sequentially as the heating medium 9 directly, and the form of utilization or utilization is not particularly limited.

In the absorption tower 1, after the chemical absorption solution 5 absorbs carbon dioxide, the by-product gas 13 is returned to the by-product gas pipe 15, and is utilized as fuel gas or the like in a subsequent process. In addition, the chemical absorption liquid from which the heated carbon dioxide was extracted in the regeneration tower 7 is returned to the absorption tower 1 as the regeneration absorption liquid 5'.

In this embodiment, the reason why "according to the characteristics of the chemical absorption liquid" is stipulated is that the heat necessary for the regeneration of the chemical absorption liquid varies greatly depending on the characteristics of the chemical absorption liquid used, and there are also differences in the operating temperature. Chemical absorption fluids with restricted range must fully take this into account when combining heat removal. This is preferably also taken into consideration in the other embodiments.

Furthermore, Fig. 4 is a schematic diagram showing a process for separating and recovering carbon dioxide from the raw material gas produced by a steel plant by chemical absorption, wherein the waste heat produced by the steel plant is utilized for the regeneration of the chemical absorption liquid, and the waste heat generated by the plant is also utilized. steam.

In the embodiment shown in FIG. 4 , a chemical absorption liquid 5 such as amines is used, and the by-product gas 3 of the raw material gas containing carbon dioxide is mixed with the chemical absorption liquid 5 at around normal temperature (for example, about 50° C.) in the absorption tower 1. Contact, after the chemical absorption liquid absorbs carbon dioxide, send the liquid to the regeneration tower 7, and use the heating medium 9 to heat to a predetermined regeneration temperature (for example, about 120°C), in order to regenerate the chemical absorption liquid, use it as much as possible or use it flexibly Low-grade exhaust heat of 500°C or below (such as exhaust heat from sintered product coolers, etc.) generated by iron and steel plants, and the insufficient part uses factory steam, etc., so as to separate and recover carbon dioxide from the chemical absorption liquid11.

In this embodiment, since the low-grade exhaust heat of 500° C. or less generated in the iron and steel plant is used as much as possible as described above, it is possible to reduce the necessary amount of factory steam. In addition, for the sake of convenience, Fig. 4 shows an example of using the 1st stage waste heat from the sintered product cooler etc. among the low-grade waste heat generated at 500°C or below in the iron and steel plant, but as shown in Fig. 3 , without a doubt, can also be utilized or utilized in multiple levels.

As described above, the above-mentioned low-grade exhaust heat can be utilized in heating medium 9 such as heating steam, or can be utilized directly as heating medium 9, and the form of utilization or utilization is not particularly limited.

In addition, factory steam etc. may be utilized as heating steam (heating medium 9) as it is, or may be utilized for heating the heating medium 9.

In the absorption tower 1, after the chemical absorption solution 5 absorbs carbon dioxide, the by-product gas 13 is returned to the by-product gas pipe 15, and is utilized as fuel gas or the like in a subsequent process. In addition, the chemical absorption liquid from which the heated carbon dioxide was extracted in the regeneration tower 7 is returned to the absorption tower 1 as the regeneration absorption liquid 5'.

As shown in Fig. 3, in this embodiment, the reason why "as far as possible" is stipulated is that the following situation also occurs: the low-grade temperature of 500°C or below produced in all steel plants that can be utilized or utilized After heat removal, there is a partial shortage of heat necessary for regeneration of the chemical absorption liquid.

In this case, the use of factory steam is stipulated because it is the easiest and cheapest to use (repurpose) factory steam that is currently used in large quantities in steelworks.

However, the present invention does not exclude the use of heat sources such as exhaust heat other than factory steam, and other exhaust heat can be sufficiently used as long as the purpose of the present invention is not impaired.

In addition, in the process of separating and recovering carbon dioxide by the chemical absorption method, the present invention can utilize or utilize the low-grade exhaust heat of 500°C or below produced by the iron and steel plant. heat energy required.

That is to say, it is preferable to use or flexibly use the above-mentioned low-grade exhaust heat as the heat energy required for heating the regeneration tower that plays a decisive role in the operation cost. The chemical absorption method is not restricted by the process principle (device configuration) shown in Fig. 1 .

In the actual process, although the degree of heating is not as good as that of the regeneration tower, in addition, there are also cases where heat exchange and heating are required. For these parts, the low-grade heat generated by the steel plant at 500°C or below can also be used or utilized. Exhaust heat.

The carbon dioxide separation and recovery process using the chemical absorption method that can be applied to the separation and recovery method of this embodiment only needs to meet the requirement of "utilizing or utilizing low-grade exhaust heat at or below 500°C generated by iron and steel plants". The process should not have any particular limitation.

Therefore, carbon dioxide is absorbed by a chemical absorption liquid from raw material gas containing carbon dioxide (by-product gas generated in a steel plant and its combustion exhaust), and then the absorption liquid is heated to separate carbon dioxide. In this process, the used The type of chemical absorption liquid, its concentration and liquid volume, the device configuration of this process, conditions such as temperature and pressure in this process, and various control methods, etc., are already known technologies for the separation and recovery of carbon dioxide using the chemical absorption method. , many improvements are also going on, and the separation and recovery method of this embodiment also includes and can be applied to these improved technologies.

In addition, these techniques are already described in many public documents and patent publications, and thus detailed description thereof will be omitted here.

(Utilization method of by-product gas after carbon dioxide extraction)

Although the above-mentioned by-product gas in the iron and steel plant has different heat, they have all been used as fuel for heat utilization in the plant. Among them, CO2 is first extracted from BFG and then reused as process gas. In this case, there are the following utilization methods: 1) fuel for gas turbines, 2) re-injection into blast furnace, and 3) use in semi-reduction refining steel craft.

In the utilization method of 1) above, the BFG is heated to increase its heat from 750kcal/Nm ³ to 1000kcal/Nm ³ , and there is no need to add auxiliary fuel such as light oil. In addition, in the utilization method of the above 2), by injecting again into the blast furnace, the removal of carbon dioxide contributes to the chemically balanced iron reduction reaction, thereby reducing the amount of coke used as a reducing agent.

In addition, according to the utilization method of 3) above, in the process of pre-reducing iron ore in the front stage of the blast furnace using natural gas and coal, the amount of natural gas and coal used can be reduced by using the reducing gas.

In this way, when carbon dioxide is extracted and reused as a process gas, it can exhibit a useful effect compared with the heat utilization in the current plant. The advantage of these effects is that they can be effectively utilized, while the exhaust gas released into the atmosphere cannot obtain the described effects by burning former fossil fuels in air and extracting carbon dioxide from the resulting combustion exhaust.

Also, in the case of producing hydrogen by reforming COG and LDG, if unnecessary carbon dioxide is extracted midway, it is possible to reduce the cost of hydrogen production. In addition, when COG and LDG are used as fuel for heat utilization in the plant, compared with the case where carbon dioxide is extracted from the above-mentioned BFG and reused as process gas, the same effect can be obtained.

(How to use the separated and recovered carbon dioxide)

Research on separating and recovering carbon dioxide and storing it in the ground or sea such as aquifers and depleted natural gas fields for the purpose of large-scale immobilization is being carried out mainly by the Global Environmental Industrial Technology Research Institute. In addition, the use of EOR (Compulsory Oil Recovery Method) and ECBM (Compulsory Recovery of Coal Buried Methane Gas) has already begun mainly overseas. In addition, even in water-soluble natural gas fields, it is possible to inject and immobilize carbon dioxide for forced recovery of natural gas.

Among them, carbon dioxide is worthless when it is stored in aquifers or in the ground or sea of depleted natural gas fields for the purpose of large-scale immobilization. Thus, recycling costs are preferably as cheap as possible. In this regard, carbon dioxide can be separated and recovered at a lower cost than carbon dioxide separated and recovered from combustion emissions of conventional power plants.

On the other hand, each steel plant produces about 10,000 tons of carbon dioxide per year. In the converter of the steel plant, carbon dioxide can be used in the bottom tuyere. Carbon dioxide emissions can be reduced by replacing carbon dioxide purchased from the market.

Next, the second embodiment of the present invention relates to a method and an apparatus for separating and recovering carbon dioxide from a carbon dioxide source.

The carbon dioxide separation and recovery device is a device for separating and recovering carbon dioxide from a carbon dioxide source. It is characterized in that: the device has the following components: carbon dioxide absorption equipment: used to absorb carbon dioxide from the carbon dioxide-containing gas from the carbon dioxide generation source; absorption medium regeneration equipment : Used to separate carbon dioxide from the absorption medium that has absorbed carbon dioxide by using the heat source of the absorption medium regeneration field to regenerate the absorption medium; carbon dioxide absorption medium: circulate between the two equipment as a transmission medium for carbon dioxide; and sending piping and return piping: used for transportation Carbon dioxide absorption medium; wherein, the above-mentioned carbon dioxide absorption equipment is installed near the carbon dioxide generation source, and the above-mentioned absorption medium regeneration equipment is installed in a place different from the place where the carbon dioxide generation source is located.

In addition, the method of separating and recovering carbon dioxide is a method of separating and recovering carbon dioxide from a carbon dioxide generating source, and is characterized in that a carbon dioxide absorbing device installed close to the carbon dioxide generating source is used, and a carbon dioxide absorbing medium is used to remove carbon dioxide from the carbon dioxide-containing gas supplied from the carbon dioxide generating source. After absorbing carbon dioxide, the carbon dioxide absorbing medium is heated by a heat source for absorbing liquid regeneration, and carbon dioxide is separated by using an absorbing liquid regeneration device located in a different location from the carbon dioxide absorbing device.

In the embodiment of the separation and recovery method and device, by combining the carbon dioxide generation source and the absorption heat regeneration heat source in different places, the carbon dioxide can be separated and recovered effectively and cheaply.

For example, by combining an adjacent thermal power plant (carbon dioxide generation source) and a heat exhaust source in a steel plant (absorption heat regeneration heat source), it is possible to separate carbon dioxide at a lower cost than before.

In this embodiment, as in the first embodiment, a chemical absorption method can be used, but there is no limitation to this, and a method of separating and recovering carbon dioxide that requires other heat can also be used. As a method of separation and recovery, chemical absorption is preferred, and therefore, the description will be made along the lines of chemical absorption. In addition, although this embodiment is demonstrated in detail using drawing, this embodiment is not limited to the content of illustration.

Figures 5 to 9 show a device (process) for separating and recovering carbon dioxide by combining carbon dioxide generation sources and absorption heat regeneration heat sources in different places. Note that, in these figures, the same reference numerals are assigned to the same constituent elements of devices and the like, and their descriptions are sometimes omitted in FIG. 6 and later in order to avoid duplication.

As shown in FIG. 5 , the device 50 for separating and recovering CO ₂ from the CO ₂ generation source in this embodiment has the configuration of a CO ₂ absorption facility 55 for extracting CO 2 containing CO ₂ supplied from the CO ₂ generation source 53 through piping. In the gas, _CO2 absorption medium 57 is used to absorb _CO2 ; absorption medium regeneration equipment 61: used to separate carbon dioxide from the absorption medium 57 that has absorbed carbon dioxide with absorption medium regeneration heat source 63 to regenerate the absorption medium; _CO2 absorption medium 57: Circulate between _CO2 absorption equipment 55 and _CO2 absorption equipment 55 as the conveying medium of carbon dioxide; And send out piping 59 and return piping 65: be used for conveying carbon dioxide absorption medium 57; Wherein, above-mentioned _CO2 Absorbing equipment 55 is arranged on Near the CO ₂ generation source 53, the above-mentioned absorption medium regeneration equipment 61 is installed in a place different from the place where the carbon dioxide generation source 53 is located.

Therefore, the method for separating and recovering CO ₂ from the CO ₂ generation source of the present embodiment using the above-mentioned device 51 is circulated in such a manner that the absorption device 55 for CO 2 close to the CO ₂ generation source is used, and the CO ₂ is recovered from the CO ₂ In the _CO2 -containing gas supplied from the generation source 53, the _CO2 absorption medium 57 circulated between the CO2 absorption equipment 55 and the absorption liquid regeneration equipment 61 is used as the _CO2 transport medium 57 to _{absorb CO2} , and the The delivery pipe 59 for transporting the _CO2 absorption medium 57 is sent to the absorption liquid regeneration facility 61, and the _CO2 absorption medium 57 is heated by the heat source 63 for absorption _medium regeneration. The absorption solution regeneration facility 61 located in a different location from the CO2 generation source is used The CO ₂ is separated and returned to the CO ₂ absorption device 55 through the return pipe 65 for the delivery of the CO ₂ absorption medium 57 .

(The separation and recovery method of this embodiment and the plant that the device may be applicable to)

The plants to which the separation and recovery method and device of this embodiment can be applied include iron and steel plants, thermal power plants, cement plants, etc. with large-scale _CO generation sources, but the present invention should not be limited to these.

This embodiment can also be applied to factories having large-scale CO ₂ generation sources other than the iron and steel factories described in the first embodiment.

For example, the separation and recovery method of this embodiment can be efficiently and inexpensively provided by combining carbon dioxide generation sources (such as thermal power plants) and absorption liquid regeneration heat sources (exhaust heat generated by other factories adjacent to thermal power plants) in different places.

(source of carbon dioxide generation)

As in the first embodiment, the carbon dioxide generation source corresponds to equipment for generating carbon dioxide in the above-mentioned factory, piping for transporting carbon dioxide-containing gas from the equipment to the next process, and the like, as in the first embodiment.

In addition, when discharging without conveying to the next process, discharge facilities (chimney etc.) are included in the carbon dioxide generation source. As the equipment that produces the above-mentioned carbon dioxide, take the blast furnace combined iron and steel plant as example, what are compatible with it are blast furnace, coke oven, converter etc., in cement plant, for example cement rotary kiln etc. are compatible with it, but the present invention will not Limited to this.

In addition, as piping, a blast furnace integrated iron and steel plant is taken as an example, and blast furnace gas (BFG) piping, coke oven gas (COG) piping, converter gas (LDG) piping, etc. are applicable thereto, but the present invention is not limited thereto at all.

(gas containing carbon dioxide (raw material gas))

The carbon dioxide-containing gas mentioned in this embodiment may be a carbon dioxide-containing gas generated by a carbon dioxide generating source. For example, by-product gases (unburned gases) such as blast furnace gas (BFG), coke oven gas (COG), and converter gas (LDG). Gas (process gas) generated in the process (process) of the above-mentioned by-product gas such as LDG.

In the present embodiment, the combustion exhaust gas of the above-mentioned by-product gas may be used as the carbon dioxide-containing gas (raw material gas). In addition, in the cement plant, for example, the outlet gas of the suspension preheater, the outlet gas of the electric dust collector, etc. are compatible with it, and the combustion exhaust of the thermal power plant is compatible with it, but the present invention does not limit it at all. here.

When the raw material gas (the by-product gas produced by the carbon dioxide generation source or its combustion exhaust gas) can be used as high-grade exhaust heat, then in the present invention, these gases are used as high-grade exhaust heat after the utilization is completed. It is used because the temperature when absorbing carbon dioxide by the chemical absorption method can be a temperature near normal temperature.

One of the source gases may be used for the separation and recovery of carbon dioxide alone, or two or more of them may be mixed. In addition to the mixed form of by-product gases and the mixed form of combustion exhaust gases of by-generated gases among the two or more kinds of mixed forms, it also includes the mixed form of combustion exhaust gases of by-generated gases and by-generated gases form.

That is, in this embodiment, a plurality of carbon dioxide absorbing facilities are installed close to a plurality of carbon dioxide generation sources, and various raw material gases can be processed.

In the source gas, the concentrations of CO ₂ in the BFG, COG, and LDG are the same as those described in the first embodiment, so the description thereof will be omitted here.

The _CO2 concentration of the gas at the outlet of the suspension preheater produced in the cement plant is about 14% by volume, and the _CO2 concentration of the gas at the outlet of the electric precipitator is about 9% by volume. In addition, the concentration of CO ₂ in the combustion exhaust gas generated by a thermal power plant is about several to several ten percent by volume.

This embodiment can also be applied to any of these source gases. As the source gas, a source gas with a high carbon dioxide concentration is preferable, and it can be said that BFG, BFG combustion exhaust, COG combustion exhaust, LDG combustion exhaust, and a mixed gas of these gases and other gases can be used.

Furthermore, as will be described later, it is also possible to apply the gas generated in the process of reforming COG and LDG to produce hydrogen. When carbon dioxide is separated and recovered by chemical absorption or the like from these source gases with high carbon dioxide concentration, the same effects as those described in the first embodiment can be obtained.

As the CO ₂ absorption medium, the same absorption medium as that of the chemical absorption liquid described in the first embodiment can be used, and there should be no particular limitation.

As a carbon dioxide absorption facility for absorbing carbon dioxide, the same absorption facility as the absorption tower described in the first embodiment can be used, and the present invention should not be particularly limited thereto.

As an absorption medium regeneration facility for separating carbon dioxide from an absorption medium that has absorbed carbon dioxide using a heat source for absorption medium regeneration to regenerate the absorption medium, the same regeneration facility as the regeneration tower described in the first embodiment can be used, but the present invention should not will be specifically limited to this.

In order to transport the carbon dioxide absorbing medium to circulate between the carbon dioxide absorbing facility and the absorbing medium regenerating facility, a delivery pipe and a return pipe are provided between the two facilities.

As a heat source for the regeneration of the absorption medium preferably process exhaust heat is used. Specifically, it is the exhaust heat generated in the ironmaking process or the exhaust heat generated in the cement manufacturing process, and it is preferably low-grade exhaust heat at or below 500°C, more preferably at or below 400°C, but the present invention should not limited to this. Here, the exhaust heat generated in the ironmaking process is the same as that described in the first embodiment, and thus its description is omitted here.

Exhaust heat generated in the cement manufacturing process includes, for example, exhaust gas from a suspension preheater (about 380°C), exhaust gas from a clinker cooler (about 350°C), exhaust gas from an electric dust collector ( about 200°C), but the present invention should not be limited thereto.

In the present embodiment, it is also included in the technical scope of the present invention that the heat of combustion of fuel is partially utilized or utilized as the heat source for regeneration of the absorption medium.

As the heat source for regeneration of the absorption medium, in the ironmaking process, for example, sintered product coolers, hot blast stoves, blast furnace water-quenched slag cooling devices, and sintering furnaces, etc. can be enumerated (refer to specific examples 1 to 5 described later); in the cement manufacturing process Among these, for example, a suspension preheater, a clinker cooler, an electric dust collector, etc. are mentioned, but the present invention is not limited thereto at all.

That is, in this embodiment, as shown in FIG. 6, it is preferable to use process exhaust heat 63a as (a part or all of) the heat source for regeneration of the absorption liquid.

This is because, as described in the first embodiment, by using or utilizing low-grade thermal energy that is difficult to be utilized by steel plants and cement plants (among low-grade thermal energy, it is preferable to utilize or utilize high-temperature thermal energy as much as possible), it is possible to Significantly reduce the cost of separation and recovery of carbon dioxide.

In addition, the reason why low-grade exhaust heat of 500°C or less is preferable as the heat source for absorption liquid regeneration is based on the same reason as described in the first embodiment.

In this embodiment, as the heat source for regeneration of the absorption liquid, one kind of heat source may be used or utilized alone, or two or more heat sources may be used or utilized simultaneously. When the exhaust heat is used in combination to heat the heating medium to a predetermined temperature, for example, two or more types of exhaust heat may be used to heat the heating medium in such a manner that the exhaust heat temperature increases gradually starting from the exhaust heat with a lower temperature. At this time, if the final heat energy is insufficient, fuel can also be used for combustion.

That is to say, this embodiment is not necessarily limited to the situation that only utilizes or fully utilizes the exhaust heat of the process in the process of adopting the chemical absorption method to separate and recover carbon dioxide. A part of fuel gas sold as city gas or the like can be used as auxiliary fuel. Such an example is the same as that described in FIGS. 2 to 4 of the first embodiment, and therefore its description is omitted here.

Next, this embodiment is characterized in that the carbon dioxide absorbing facility is installed near the carbon dioxide generating source, and the absorption medium regeneration facility is installed at a location different from the carbon dioxide generating source.

In the present invention, a chemical absorption liquid is used as an absorption medium. Therefore, even if the piping distance is long, the power for transporting the medium is absolutely less than that of the raw material gas (gas). On the other hand, when the carbon dioxide absorbing equipment is installed in a different place (separated from the source) without being close to the carbon dioxide generation source, in order to supply the raw gas to the _CO2 absorbing equipment, the distance of the raw gas supply piping is lengthened, and the transport medium, that is, the gas Compared with the case of conveying liquid, the power of the pump is absolutely large.

Specifically, it is preferable to install the absorption medium regeneration facility in the vicinity of the heat source for absorption medium regeneration, which is different from the installation location of the carbon dioxide generation source. This is because the length of piping that transports the heat medium (process waste gas and combustion gas, etc.) from the heat source for absorption medium regeneration to the absorption medium regeneration equipment is lengthened, thereby preventing temperature drops and thermal efficiency losses during heat medium transportation. low.

That is to say, when combining the carbon dioxide generation source and the absorption medium regeneration heat source phase in different places, by making the carbon dioxide absorption equipment close to the carbon dioxide generation source, it is possible to shorten the amount of raw material that requires a large transport power compared with the absorption medium (absorption liquid). The conveying distance of the gas piping is to transport the absorbing medium (absorbing liquid) between the carbon dioxide absorbing equipment and the absorbing medium regeneration equipment in different places, so that the carbon dioxide can be separated and recovered efficiently and inexpensively.

In addition, compared with the absorption medium regeneration equipment being close to the carbon dioxide generation source and transporting the heat medium from the absorption medium regeneration heat source in a different location, the absorption medium regeneration equipment can be placed close to the absorption medium regeneration heat source in a different location, which can greatly shorten the regeneration time through piping. With the distance between the heat source and the heat medium, the temperature drop of the heat source can be suppressed, and carbon dioxide can be separated and recovered efficiently and inexpensively.

Specifically, the distance A between the above-mentioned carbon dioxide generation source and the carbon dioxide absorption equipment, the distance B between the absorption medium regeneration equipment and the heat source for absorption medium regeneration, and the distance C between the carbon dioxide absorption equipment and the absorption medium regeneration equipment preferably satisfy A relational expression of A<C and B<C (for example, refer to FIGS. 10 to 14 ).

Here, in the case of a one-to-one relationship between the carbon dioxide absorption equipment and the absorption medium regeneration equipment, the explanation is the same as above; in the case of one-to-many, many-to-1, and many-to-many, each All of the above-mentioned relationships are preferably satisfied between the device and the absorption medium regeneration device.

In addition, as the heat source for regeneration of the absorption medium, in the case of multi-stage heat removal from processes with different temperature levels, the distance between the absorption medium regeneration equipment and the heat source with the highest temperature level is set as B (for example, refer to Figure 12 and 14).

More specifically, the piping distance X for supplying the gas containing carbon dioxide from the carbon dioxide generating source to the carbon dioxide absorbing device, the sending piping distance Y and the returning piping distance Z of the carbon dioxide absorbing medium preferably satisfy 2X<(Y+Z) Furthermore, if the piping distance for supplying thermal energy (such as process exhaust gas and fuel combustion exhaust gas) from the heat source for absorption medium regeneration to the absorption medium regeneration equipment is set to W, it is more preferable to satisfy ( X+W)<(Y+Z) relational expression.

At this time, as the heat source for regeneration of the absorption medium, in the case of multi-stage heat removal from processes with different temperature levels, the distance between the absorption medium regeneration equipment and the heat source with the highest temperature level is set as W (for example, refer to Fig. 12 and 14).

This embodiment may also include one or more carbon dioxide absorption equipment and one or more absorption liquid regeneration equipment. For example, when there are a plurality of carbon dioxide generation sources, carbon dioxide absorption facilities may be respectively installed close to the plurality of carbon dioxide generation sources. Similarly, in the case that process waste heat that can be utilized as a heat source for absorption medium regeneration belongs to a plurality of locations, the absorption medium regeneration equipment may be respectively installed close to the plurality of heat sources for absorption medium regeneration.

That is to say, the carbon dioxide absorption equipment and the absorption liquid regeneration equipment can have any relationship of 1-to-1, many-to-1, and many-to-many. Regarding the absorption liquid regeneration equipment, the heat of the heat source for the regeneration of the absorption medium is collected together, from It is preferable in terms of equipment cost and running cost.

For example, as shown in Figure 7, as an example of many pairs of 1, two carbon dioxide absorbing devices 55a and 55b are arranged close to two carbon dioxide generating sources 53a and 53b respectively, and independent sending piping 59a and returning piping 65a and sending piping 59b and returning piping The pipes 65b are installed in different places, specifically, between the two carbon dioxide absorbing facilities and the one absorption liquid regeneration facility 61 installed near the regeneration heat source 63 .

Fig. 7 shows an example in which the sending piping and the returning piping are formed independently of two systems, but it is also possible to integrate the piping of the two systems into one system in the middle, and send the absorption medium 57 to one absorption liquid for regeneration. Plant 61, when returning to 2 carbon dioxide absorbing plants 55a and 55b, is divided into 2 systems.

In addition, regarding the case where a plurality of carbon dioxide absorption equipment and absorption liquid regeneration equipment are installed, for example, as shown in FIG. The carbon dioxide absorbing devices 55a to 55c are installed in different locations, specifically, the absorbing medium regeneration devices 61a and 61b are installed close to the respective regeneration heat sources 63a and 63b.

As the delivery piping and the return piping provided between the two devices in this case, the three sending pipings 59a to 59c and the return piping 65a to 65c connected to each other of the three carbon dioxide absorbing devices 55a to 55c may be connected to each other. They are collected in the middle and are redistributed to each of the absorption medium regeneration facilities 61a to 61b as two sending pipes 59d to 59e and return pipes 65d to 65e.

At this time, when the _CO2 absorption capacity required by the three carbon dioxide absorbers, for example, the amount of raw gas processed by each carbon dioxide absorber and the _CO2 concentration in the gas are different, in order to be able to supply the corresponding amount of absorption medium , the pipe diameters (areas) of the sending pipes 59a to 59c and the return pipes 65a to 65c and the conveying capabilities of the conveying pumps and the like can be adjusted.

Specifically, when the carbon dioxide absorption capacity of each carbon dioxide absorption device 55a: 55b: 55c is 5: 3: 2, for example, the piping area of the delivery piping 59a: 59b: 59c (return piping 65a: 65b: 65c) can be made Alternatively, the transport capacity is also 5:3:2.

Similarly, when the regeneration capabilities of the two absorption medium regeneration facilities, such as the heat source for absorption medium regeneration that can be used by each absorption medium regeneration facility, etc., the pipe diameter (area) can be adjusted in order to supply the corresponding amount of absorption medium. and delivery capacity.

Specifically, when the amount of heat for regeneration of the absorption medium supplied to the respective absorption medium regeneration devices 61a: 61b is 6:4, for example, the piping area or transport capacity of the sending piping 59d: 59e (returning piping 65d: 65e) can be adjusted to Also becomes 6:4.

In addition, in this embodiment, as (a part or all of) the heat source for regeneration of the absorption liquid, it is also possible to set process exhaust heat at different temperature levels in multiple stages. This is the same as that described in the first embodiment (see FIG. 3 ).

In addition, in any one of the first embodiment and this embodiment, the heating of the absorption medium by the heat source for absorption liquid regeneration is not limited to the heating of the absorption medium in the absorption medium regeneration equipment directly, and may also be carried out in the delivery pipe. As well as multi-stage arrangement of process heat removal at different temperature levels on the absorption medium regeneration plant, whereby the absorption medium is heated.

At this time, as shown in FIG. 9 , it is preferable to use the exhaust heat in a manner that the temperature of the exhaust heat increases gradually starting from the process exhaust heat with a lower temperature. In other words, when these heat sources that can be used as heat sources for regeneration are dispersed in a plurality of places, as shown in FIG. 9 , the delivery piping can be guided near these heat sources and used as heat sources for regeneration.

At this time, the waste heat can be utilized in the manner of gradually increasing heat discharge temperature starting from the heat discharge of the process with a lower temperature, and the heat discharge 63a (heat source temperature T1) from the heat source with a lower temperature, that is, the process process, to the heat source with a higher temperature, namely The sequence of process exhaust heat 63b (heat source temperature T2) is arrange|positioned so that delivery piping may pass near a heat source.

In addition, the absorption medium regeneration device 61 is installed near the heat source with the highest temperature, that is, process exhaust heat 63c (heat source temperature T3). Here, T1<T2<T3. Thus, during the process of the absorption liquid passing through the delivery pipe 59, the absorption medium is slowly preheated to a high temperature and sent to the absorption medium regeneration device 61, where heat necessary for regeneration is given to separate carbon dioxide. .

The absorption medium passing through the delivery pipe is usually liquid, but as described above, when the delivery pipe is heated by a heat source, sometimes the absorption medium may be partially vaporized, or the gas (the gas contains the In the state of separated carbon dioxide gas), but from the perspective of reducing the transmission power, as a heat source for heating the transportation piping, it is preferably kept at such a temperature that the absorption medium will not be vaporized or the carbon dioxide will not be vaporized. separate.

In other words, the absorption medium is preferably denser than a mere gas, particularly preferably a liquid. The liquid may contain a part of solid or gas as long as it does not significantly affect the transmission power.

In addition, in any one of the first embodiment and the present embodiment, it is also possible to cool the absorption medium in the return pipe by utilizing a cold and heat source on the return pipe. That is, it is preferable from the viewpoint of carbon dioxide absorption efficiency that the absorption medium in the return pipe be cooled to a lower temperature before being returned to the carbon dioxide absorption facility.

As shown in Figures 1 to 4 of the first embodiment, cooling is usually carried out in the following manner, that is, heat exchange is performed with the absorption medium in the delivery pipe, but in steel plants or other large factories, sometimes using A large number of cold and heat sources may sometimes utilize a part.

However, since the carbon dioxide absorbing facility of the present invention and the absorbing medium regenerating facility are located in different locations (outside locations), they can be cooled to around the outside temperature by natural cooling. Therefore, it is particularly effective to use the above-mentioned cold and heat sources in the case of high outside temperature such as in summer.

The above is the description of this embodiment. Hereinafter, specific examples will be briefly described using the drawings, but the present invention is by no means limited thereto.

10 to 13 schematically show specific examples of separating and recovering carbon dioxide by combining carbon dioxide generation sources and absorption liquid regeneration heat sources in different locations.

Note that, in these drawings, the same reference numerals are attached to the same components such as devices, and therefore descriptions thereof may be omitted in order to avoid repetition after FIG. 11 .

(Example 1)

The composition of the carbon dioxide separation and recovery device 100 shown in Figure 10 includes:

CO ₂ absorption equipment (sometimes simply referred to as an absorption tower) 95 for absorbing CO 2 from BFG (with a CO ₂ concentration of 20 to 25% by volume) using a CO ₂ absorption medium 97, wherein BFG is a gas containing _{CO 2} , the gas is supplied by the BFG main pipe 93 as the _CO2 generation source through the piping 94;

Absorption medium regeneration equipment (regeneration tower 101), which is used to separate CO from the absorption medium ₉₇ that has absorbed CO ₂ to regenerate the absorption medium 97 by utilizing the heat source for absorption medium regeneration, that is, the sinter cooler exhaust heat (250-350° C.);

Absorption medium 97, which circulates between absorption tower 95 and regeneration tower 101 as a transport medium for CO ₂ ; and

Outgoing piping 99 and return piping 105 for conveying the absorption medium 97;

Wherein, the above-mentioned absorption tower 95 is installed in the vicinity of the BFG main pipe 93, and the above-mentioned regeneration tower 101 is installed in a place different from the place where the BFG main pipe 93 is located. The vicinity of 103a.

Therefore, using the CO separation and recovery method of the above-mentioned device 100, the absorption tower 95 close to the BFG main pipe ₉₃ is adopted, and the absorption medium 97 circulating between the absorption tower 95 and the regeneration tower 101 as a _CO transport medium is used, and the main pipe of the BFG CO ₂ is absorbed in the BFG supplied by 93, and then the absorption medium 97 is sent to the regeneration tower 101 through the delivery pipe 99 for transporting the absorption medium 97, and then the absorption medium 97 is heated by the exhaust heat of the sinter cooler, and the main pipe of the BFG is adopted 93 The regeneration tower 101 at a different location separates the CO ₂ and then returns it to the absorption tower through the return pipe 105 for transporting the absorption medium 97 for recycling.

Here, the distance X of the pipe 94 for supplying BFG from the BFG main pipe 93 to the absorption tower 95 = the distance A between the BFG main pipe 93 and the absorption tower 95 is used to supply the sinter cooler 103a to the regeneration tower 101 The distance W of the piping 96 for exhausting heat = the distance B between the sintering cooler 103a and the absorption tower 95, the distance Y of the sending piping 99 = the distance Z of the return piping 105 = the distance C between the absorption tower 95 and the regeneration tower 101, Their constitutional relationship satisfies any one of 2X<(Y+Z), (X+W)<(Y+Z), and A<C and B<C.

The BFG produced by the blast furnace is supplied as fuel gas to the steel plant's own power plant or a nearby thermal power plant through the BFG main pipe. Here, it is advantageous to install a valve on the BFG main pipe to separate part or all of the BFG with CO ₂ After the carbon dioxide is removed by the recovery device 100, it can be supplied to a self-owned power plant or a thermal power plant as fuel with high combustion efficiency (the same effect as that described in the first embodiment can be obtained in this point).

(Specific example 2)

The _CO2 separation and recovery device 110 shown in Figure 11 is used as a heat source for regeneration of the absorption medium (a part or all) of hot blast stove exhaust gas (150-300° C.), and the regeneration tower 101 is installed at the heat source for regeneration of the absorption medium. The configuration of the vicinity of the hot blast stove 103b is the same as that of the CO ₂ separation and recovery device 100 shown in FIG. 10 .

Therefore, the _CO2 separation and recovery method using the above-mentioned device 110 is the same as the _CO2 separation and recovery method using the _CO2 separation and recovery device 100 shown in FIG. .

Here, the distance X of the piping 94=the distance A between the BFG main pipe 93 and the absorption tower 95, the distance W of the piping 96 for supplying the hot blast stove exhaust gas from the hot blast stove 103b to the regeneration tower 101=the hot blast stove 103b and the absorption tower The distance B between 95, the distance Y=return pipe 105 of the distance Y=return piping 105 distance C=the distance C between the absorption tower 95 and the regeneration tower 101, and their composition relationship satisfies 2X<(Y+Z), (X+ W)<(Y+Z), and any relational expression among A<C and B<C.

(Example 3)

The CO ₂ separation and recovery device 120 shown in FIG. 12 is an example of process exhaust heat in which different temperature levels are set in multiple stages (two stages) as part or all of the heat source for absorption liquid regeneration.

Among the heat sources for absorption medium regeneration, as a heat source with a high temperature level, (a part or all) of hot blast furnace exhaust (150-300°C) is used, and as a heat source with a low temperature level, water-quenched slag drainage from a blast furnace (60 ~90°C), the regeneration tower 101 is installed near the hot blast stove 103b, which is the heat source for regeneration of the absorption medium, and the delivery pipe 99 is arranged so as to pass through a position close to the blast furnace water quenching slag cooling device. Except for this point, the rest of the configuration is the same as The same applies to the CO ₂ separation and recovery device 100 shown in FIG. 10 .

Therefore, in the _CO2 separation and recovery method using the above-mentioned device 120, the absorption medium 97 in the delivery pipe 99 is first heated (preheated) by using the water-quenched slag drainage of the blast furnace, and then the absorption medium 97 is heated by the exhaust gas of the hot blast stove. The rest of the configuration is the same as that of the CO ₂ separation and recovery device 100 shown in FIG. 10 .

Here, the distance X of the piping 94=the distance A between the BFG main pipe 93 and the absorption tower 95, the distance W of the piping 96 for supplying the hot blast stove exhaust gas from the hot blast stove 103b to the regeneration tower 101=the hot blast stove 103b and the absorption tower The distance B between 95, the distance Y=return pipe 105 of the distance Y=return piping 105 distance C=the distance C between the absorption tower 95 and the regeneration tower 101, and their composition relationship satisfies 2X<(Y+Z), (X+ W)<(Y+Z), and any relational expression among A<C and B<C.

(Example 4)

The CO ₂ separation and recovery device 130 shown in FIG. 13 is configured to supply combustion gas containing CO ₂ to the absorption tower 95 through a pipe 94 a from a power plant (combined thermal power plant) 93 a in a steel plant that is a source of CO ₂ generation. Except for the exhaust gas (CO ₂ concentration 8 to 20 vol%), the rest of the configuration is the same as that of the CO ₂ separation and recovery apparatus 100 shown in FIG. 10 .

Therefore, in the method of separating and recovering CO ₂ using the above-mentioned device 130, the absorption tower 95 near the own power plant 93a in the iron and steel factory is used to absorb CO ₂ from the combustion exhaust gas supplied from the self-owned power plant 93a using the absorption medium 97, and remove Except for this point, the rest is the same as the CO ₂ separation and recovery method using the CO ₂ separation and recovery apparatus 100 shown in FIG. 10 .

Here, the distance X of the pipe 94a = the distance A between the self-owned power plant 93a and the absorption tower 95, and the distance W of the pipe 96 for supplying the sinter cooler exhaust gas from the sinter cooler 103a to the regeneration tower 101 = the sinter cooler The distance B between 103a and the absorption tower 95, the distance Y of the delivery pipe 99=the distance Z of the return pipe 105=the distance C between the absorption tower 95 and the regeneration tower 101, and their composition relationship satisfies 2X<(Y+Z) , (X+W)<(Y+Z), and any one of the relational expressions among A<C and B<C.

In addition, the own power plant in the iron and steel factory can use BFG or BFG and heavy oil from which carbon dioxide has been removed by using the CO ₂ separation and recovery device shown in Figures 10 to 12 as fuel for thermal power generation. The CO ₂ concentration of the above-mentioned combustion exhaust gas is 8 to 20% by volume, which is an example when using ordinary BFG and heavy oil.

(Example 5)

The structure of the _CO2 separation and recovery device 140 shown in FIG. ₁₄ is to supply the _combustion exhaust gas ( _CO2 Concentration of 8 to 15% by volume), and as a heat source for regeneration of the absorption liquid, it is an example of process heat removal in a steel plant with multiple (three) levels of different temperature levels.

Among the heat sources for absorption medium regeneration, as the heat source with the highest temperature level, the sinter cooler is used to discharge heat (250-350°C), and as the heat source with the second highest temperature level, the hot blast stove exhaust gas (150-300°C) is used (part of or all), in addition, as a heat source with a lower temperature level, the blast furnace water quenching slag cooling water (60-90°C) is used, and the regeneration tower 101 is installed in a place different from that of the thermal power plant 93b. In the vicinity of the sinter cooler 103a of the heat source for medium regeneration, the delivery pipe 99 is arranged so as to pass through the position close to the blast furnace water-quenched slag cooling device 103c and the hot blast stove 103b. The CO ₂ separation and recovery device 100 is the same.

Therefore, in the _CO2 separation and recovery method using the above-mentioned device 140, the absorption tower 95 near the thermal power plant 93b adjacent to the iron and steel plant is used, and the absorption medium 97 is used to absorb _CO2 from the combustion exhaust gas supplied by the thermal power plant 93b, and then Starting from the exhaust heat of the low-temperature technological process, the exhaust heat is used in a manner of increasing the exhaust heat temperature. First, the water-quenched slag of the blast furnace is used to drain water, and then the absorption medium 97 in the pipeline 99 is sent out by heating (preheating) with the exhaust gas of the hot blast stove, and then The method of separating and recovering CO ₂ using the CO ₂ separation and recovery device 100 shown in FIG. 10 is the same as that of heating the absorption medium 97 by using the sintered cooler to discharge heat.

Here, the distance X of the piping 94b = the distance A between the thermal power plant 93b and the absorption tower 95, the distance W of the piping 96 for supplying the exhaust heat of the sintering cooler from the sintering cooler 103a to the regeneration tower 101 = the sintering cooler The distance B between 103a and the absorption tower 95, the distance Y of the delivery pipe 99=the distance Z of the return pipe 105=the distance C between the absorption tower 95 and the regeneration tower 101, and their composition relationship satisfies 2X<(Y+Z) , (X+W)<(Y+Z), and any one of the relational expressions among A<C and B<C.

In addition, as the carbon dioxide separation and recovery process (device and method) that can be applied in this embodiment, using the chemical absorption method, as long as the above-mentioned "carbon dioxide absorption equipment is installed near the carbon dioxide generation source, and the above-mentioned absorption medium regeneration equipment is installed in the vicinity of the carbon dioxide There should be no special restriction on the requirement that the place where the source of occurrence is located is different.

Therefore, carbon dioxide is absorbed by a chemical absorption liquid from raw material gas containing carbon dioxide (by-product gas generated in a steel plant and its combustion exhaust), and then the absorption liquid is heated to separate carbon dioxide. In this process, the used The type of chemical absorption liquid, its concentration and liquid volume, the device configuration of this process, conditions such as temperature and pressure in this process, and various control methods, etc., are already known technologies for the separation and recovery of carbon dioxide using the chemical absorption method. , and many improvements are in the works.

Needless to say, this embodiment also includes these improved techniques, which can be used as separation and recovery processes, but these techniques have been published in many known documents and patent publications, so detailed description thereof will be omitted here.

(Utilization method of by-product gas after carbon dioxide extraction)

The utilization method of the by-product gas after carbon dioxide extraction is the same as that described in the first embodiment, so the description thereof will be omitted here.

(How to use raw material gas after carbon dioxide extraction)

As for the raw material gas after carbon dioxide extraction, those that can be used in cement plants and thermal power plants other than steel plants can be used in the same way as the by-product gas of steel plants, and those that cannot be used are not used and discharged (Refer to Figures 13 and 14).

(How to use the separated and recovered carbon dioxide)

The method of using the separated and recovered carbon dioxide is the same as that described in the first embodiment, so its description is omitted here.

As described above, according to the first embodiment of the present invention, the following effects can be obtained.

1) Compared with the combustion exhaust gas of thermal power plants, carbon dioxide can be separated and recovered from the by-product gas (unburned gas) of iron and steel plants with a high carbon dioxide ratio by chemical absorption, thereby making the separation and recovery equipment compact. Although it also depends on the raw gas used, for example, if BFG from a steel plant is used as raw gas instead of combustion exhaust gas with low CO2 concentration in a coal-fired power plant, the equipment cost can be reduced by 30% or more.

2) The operating cost of carbon dioxide separation and recovery by chemical absorption can be reduced by utilizing or utilizing low-grade energy at 0-500° C., preferably 350° C. or below, in steel plants. Specifically, in the regeneration tower used in the chemical absorption method, the thermal energy required to heat the chemical absorption liquid becomes the factor that determines the running cost of this method (about 50% to 80%). Here, because it can be used or The low-grade exhaust heat in the steel plant can be utilized, so the overall operating cost can be greatly reduced.

3) By separating and recovering carbon dioxide from the above-mentioned by-product gas or its combustion exhaust gas, it is possible to improve the thermal efficiency when the by-product gas is used as a fuel in a later stage. Although it depends on the raw material gas used, for example, when BFG from a steel plant is used as the raw material gas, the thermal efficiency can be improved by about 20% to 30%.

4) Furthermore, the combustion exhaust after using the above-mentioned by-product gas (unburned gas) as fuel gas has a higher ratio of carbon dioxide, so the separation and recovery equipment of carbon dioxide can be further miniaturized, and the efficiency of carbon dioxide in steel plants can be improved. Emission reduction (separation and recovery).

According to the second embodiment of the present invention, carbon dioxide can be efficiently and inexpensively separated and recovered from the carbon dioxide generation source by combining the carbon dioxide generation source and the absorption liquid regeneration heat source at different locations.

According to the present invention, the above effects can be obtained at the same time, and thus carbon dioxide can be separated and recovered at extremely low cost. Therefore, the present invention is also an effective and useful technique that can be industrially utilized for steel mills where cost competition is extremely fierce.

Furthermore, according to the present invention, recovered carbon dioxide can also be utilized as reducing gas in iron and steel works, for example, in the top gas cycle of a blast furnace. As a result, the amount of reducing agent used can be reduced, and the amount of coke used and the amount of _CO generated in the blast furnace can be reduced, and the increase in the total cost of the steel plant can be significantly suppressed (in some cases, the cost can be reduced).

In addition, as described above, many technologies (including the technology newly discovered by the present inventors) for converting recovered carbon dioxide into valuable products have also been proposed. The present invention suppresses an increase in product cost by combining such technologies (reduction of the total cost is also possible due to the commercial value of carbon dioxide), and provides an extremely useful technology that contributes to effective prevention of global warming.

Claims (22)

1. one kind is adopted chemical absorption method to separate the method that reclaims carbon dioxide from the secondary angry body that steel plant produce, it is characterized in that: with chemical absorbing liquid from this gas behind the absorbing carbon dioxide, at the described chemical absorbing liquid of heating carbon dioxide is able in the separation processes, utilizes or apply flexibly 500 ℃ or following low-grade heat extraction that steel plant produce.

2. one kind is adopted chemical absorption method to separate the method that reclaims carbon dioxide from the burning and gas-exhausting of the secondary angry body of steel plant's generation, it is characterized in that: with chemical absorbing liquid from this gas behind the absorbing carbon dioxide, at the described chemical absorbing liquid of heating carbon dioxide is able in the separation processes, utilizes or apply flexibly 500 ℃ or following low-grade heat extraction that steel plant produce.

3. one kind is adopted chemical absorption method to separate the method that reclaims carbon dioxide from the process gas that modifying process produces, wherein modifying process is used for producing hydrogen from the secondary angry body that steel plant produce, described method is characterised in that: with chemical absorbing liquid from this gas behind the absorbing carbon dioxide, make in the technology of carbon dioxide separation at the described chemical absorbing liquid of heating, utilize or apply flexibly 500 ℃ or following low-grade heat extraction that steel plant produce.

4. according to the separation and recovery method of each described carbon dioxide of claim 1～3, it is characterized in that: supply with gas concentration lwevel in the angry body of described pair, burning and gas-exhausting or the process gas of described chemical absorption method and be 15 volume % or more than.

5. according to the separation and recovery method of each described carbon dioxide of claim 1～4, it is characterized in that: the angry body of described pair is at least a kind among blast furnace gas, oven gas and the converter gas.

6. according to the separation and recovery method of each described carbon dioxide of claim 1～5, it is characterized in that: all or part of utilization of the necessary heat of regeneration of described chemical absorbing liquid or apply flexibly the heat extraction that steel plant produce.

7. according to the separation and recovery method of each described carbon dioxide of claim 1～6, it is characterized in that: according to the characteristic of described chemical absorbing liquid, for the multistage utilization of the regeneration of chemical absorbing liquid or apply flexibly the suitable heat extraction that steel plant produce.

8. according to the separation and recovery method of each described carbon dioxide of claim 1～7, it is characterized in that:, use factory's steam simultaneously for the regeneration of described chemical absorbing liquid utilizes or apply flexibly the heat extraction that steel plant produce as much as possible.

9. device that separate to reclaim carbon dioxide from carbon dioxide generation source is characterized in that the formation of this device comprises:

Carbon dioxide absorption equipment, it is used for adopting carbon dioxide absorption medium absorbing carbon dioxide from the gas of being supplied with by carbon dioxide generation source that contains carbon dioxide;

The absorbing medium reclaim equiment, it is used for utilizing absorbing medium regeneration to use the thermal source separating carbon dioxide with the regeneration absorbing medium from the absorbing medium that has absorbed carbon dioxide;

The carbon dioxide absorption medium, its pumped (conveying) medium as carbon dioxide circulates at two equipment rooms; And

Send pipe arrangement and return pipe arrangement, it is used for the transport of carbon dioxide absorbing medium;

Wherein, the absorption equipment of described carbon dioxide is arranged near the carbon dioxide generation source, and described absorbing medium reclaim equiment is arranged on and carbon dioxide generation different place, residing place, source.

10. the separating and reclaiming device of carbon dioxide according to claim 9 is characterized in that: distance A, absorbing medium reclaim equiment between source and the carbon dioxide absorption equipment takes place described carbon dioxide regenerates with absorbing medium and satisfies the relational expression of A＜C and B＜C with the distance C apart between B and carbon dioxide absorption equipment and the absorbing medium reclaim equiment between the thermal source.

11. the separating and reclaiming device according to claim 9 or 10 described carbon dioxide is characterized in that: be used for the source taking place and supply with sending the pipe arrangement distance Y and returning pipe arrangement apart from Z and be used for from absorbing medium regeneration with thermal source at least one relational expression among the relational expression of the relational expression that satisfies 2X＜Y+Z between the pipe arrangement distance W of absorbing medium reclaim equiment heat supply and X+W＜Y+Z of the pipe arrangement distance X of the gas that contains carbon dioxide, described carbon dioxide absorption medium to carbon dioxide absorption equipment from described carbon dioxide.

12. the separating and reclaiming device according to each described carbon dioxide of claim 9～11 is characterized in that: described absorbing medium reclaim equiment is arranged on and is used as absorbing medium regeneration with near the technical process heat extraction source of thermal source.

13. the separating and reclaiming device according to each described carbon dioxide of claim 9～12 is characterized in that: utilize the technical process heat extraction as described regeneration of absorption solution part or all with thermal source.

14. the separating and reclaiming device according to each described carbon dioxide of claim 9～13 is characterized in that: the formation of this separating and reclaiming device comprises described 1 cover or overlaps carbon dioxide absorption equipment and 1 cover or overlap regeneration of absorption solution equipment more more.

15. the separating and reclaiming device according to each described carbon dioxide of claim 9～14 is characterized in that: as described regeneration of absorption solution part or all, the multistage technical process heat extraction that utilizes the different temperatures level with thermal source.

16. method of separating the recovery carbon dioxide from carbon dioxide generation source, it is characterized in that: adopt the carbon dioxide absorption equipment that is provided with near carbon dioxide generation source, utilize carbon dioxide absorption medium absorbing carbon dioxide from the gas of supplying with by this carbon dioxide generation source that contains carbon dioxide, utilize regeneration of absorption solution to heat this carbon dioxide absorption medium with thermal source afterwards, employing makes carbon dioxide separation with the regeneration of absorption solution equipment that carbon dioxide generation source is in different places.

17. the separation and recovery method of carbon dioxide according to claim 16 is characterized in that: the distance C apart between B and carbon dioxide absorption equipment and the absorbing medium reclaim equiment between the thermal source of the distance A between described carbon dioxide generation source and the carbon dioxide absorption equipment, absorbing medium reclaim equiment and absorbing medium regeneration usefulness satisfies the relational expression of A＜C and B＜C.

18. the separation and recovery method according to claim 16 or 17 described carbon dioxide is characterized in that: be used for the source taking place and supply with sending the pipe arrangement distance Y and returning pipe arrangement apart from Z and be used for from absorbing medium regeneration with thermal source at least one relational expression among the relational expression of the relational expression that satisfies 2X＜Y+Z between the pipe arrangement distance W of absorbing medium reclaim equiment heat supply and X+W＜Y+Z of the pipe arrangement distance X of the gas that contains carbon dioxide, described carbon dioxide absorption medium to carbon dioxide absorption equipment from described carbon dioxide.

19. the separation and recovery method according to each described carbon dioxide of claim 16～18 is characterized in that: described absorbing medium reclaim equiment is arranged on and is used as absorbing medium regeneration with near the technical process heat extraction source of thermal source.

20. the separation and recovery method according to each described carbon dioxide of claim 16～19 is characterized in that: utilize the technical process heat extraction as described regeneration of absorption solution part or all with thermal source.

21. the separation and recovery method according to each described carbon dioxide of claim 16～20 is characterized in that: this separation and recovery method uses described 1 cover or overlaps carbon dioxide absorption equipment and 1 cover or overlap regeneration of absorption solution equipment more more.

22. the separation and recovery method according to each described carbon dioxide of claim 16～21 is characterized in that: as described regeneration of absorption solution part or all, the multistage technical process heat extraction that utilizes the different temperatures level with thermal source.

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