CN1054392C - Method of coal liquefaction - Google Patents

Abstract

A method for coal liquefaction, comprising the steps of: (a) producing coal slime from coal powder, a solvent and a catalyst, wherein the solvent is 100 to 233 parts by weight based on 100 parts by weight of coal, and the catalyst is 0.5 to 10 parts by weight; (b) reacting coal slime and coke oven gas at a temperature of 350 to 480°C and a pressure of 20 to 200 atm to form liquefied products; (c) separating liquefied products into liquefied slurry and gas; (d) distilling liquefied slurry to form liquefied oil and solvent refining coal; (e) recycling said liquefied oil as solvent for step (a).

Description

coal liquefaction method

The present invention relates to a method of coal liquefaction, more particularly to a method of coal liquefaction to produce solvent refined coal.

Figure 3 shows a flow chart of a conventional process for coal liquefaction. The term "coal liquefaction" in the specification of the present invention is defined as a reaction of producing liquefied oil by reacting coal with hydrogen and a reaction of producing solvent refined coal. According to the conventional liquefaction method, coal powder and liquefied oil (solvent) obtained from the distillation step described below are charged into the slurry tank 1, and they are mixed under stirring to prepare coal slime. This slime is pressurized and mixed with a gas mainly composed of hydrogen (recycled hydrogen), and then fed to the preheater 2, where the hydrogen is separated in the purification step described below. The coal slime fed into the preheater 2 is pressurized to 100 atm or higher and heated to 400° C. or higher, and then fed into the coal liquefaction reactor 3 . Coal liquefaction reactor 3 carries out liquefaction reaction at high temperature under positive hydrogen pressure.

The product of the liquefaction reaction leaving the reactor 3 is fed into the gas separator 4, and the product is separated into a gas and a liquefied slurry containing liquefied oil and unliquefied substances.

The liquefied slurry contains a large amount of ash and unliquefied material mainly composed of unreacted organic residues. Since this unliquefied material causes difficulties in subsequent processing such as distillation, the liquefied slurry is sent to filter 50 to separate the unliquefied material. The solution free of unliquefied substances is sent to the distillation unit 5 for fractionation into light oil and fuel oil and the liquefied oil is recovered. A part of liquefied oil is added into the slurry tank 1 as a solvent for preparing coal slime. The filter cake separated by the filter 50 is sent to the hydrogen production equipment 51 as a raw material for hydrogen production and gasified in the equipment.

On the other hand, the gas separated in the gas separator 4 is sent to the gas purification unit 6 for purification. Since the gas mainly consists of hydrogen, the gas is recycled and added to the coal slime in the liquefaction reactor 3 . However, the recycled hydrogen is not sufficient for the liquefaction reaction, so hydrogen obtained by gasifying the filter residue discharged from the hydrogen producing facility 51 is added to the coal slime. The plant 51 for producing hydrogen consists of a plurality of processing steps including: a gasification step in which the residue is completely decomposed in the presence of oxygen, a purification step in order to purify the resulting decomposed gas, a hydrogen enrichment step (wherein the generated gas is The CO gas is replaced by a hydrogen-rich gas), a gas cooling step and a step of removing CO ₂ from the gas using a base. In this method, the equipment for producing hydrogen is complicated.

According to the conventional method described above, the liquefaction reaction must use hydrogen, which is produced in a particularly complex hydrogen production plant 51 . Due to the complexity of the hydrogen production plant 51, the plant is expensive (in some cases approaching 40% of the total investment in the liquefaction plant) and the operating costs involved are high. The cost part of hydrogen production therefore becomes high for the total cost of the liquefied product.

Meanwhile, the liquefaction reaction of the conventional method is carried out at a high temperature of 400 to 480° C. (usually 430 to 450° C.) and a high pressure of 100 to 300 atm (usually 150 to 200 atm). As a result, investment costs and operating costs are further increased.

The object of the present invention is to provide a coal liquefaction method which significantly reduces the cost of coal liquefaction products.

To achieve this purpose, the invention provides a coal liquefaction method, which comprises steps:

(a) produce coal slime by coal powder, solvent and catalyst, by 100 weight parts coal, described solvent is 100 to 233 weight parts, and described catalyst is 0.5 to 10 weight parts;

(b) reacting the coal slime and coke oven gas at a temperature of 350 to 480° C. and a pressure of 20 to 200 atm to form a liquefied product;

(c) separating the liquefied product into liquefied slurry and gas;

(d) distillation of liquefied slurries to form liquefied oil and solvent refined coal; and

(e) recycling said liquefied oil as a solvent in step (a).

Figure 1 is a flow diagram of one embodiment of the present invention.

Figure 2 is a flow chart of another embodiment of the present invention.

Fig. 3 is a flow chart of a conventional coal liquefaction method.

During the coal liquefaction reaction, hydrogen is added to the fragments formed by the thermal decomposition of high-molecular-weight coal, and the fragments reduce the molecular weight to produce liquefied substances. It is known that the transfer of hydrogen to pyrolysis fragments can be controlled by the three transfer processes given below.

(1) Transfer of hydrogen in coal

Coal has a part that is rich in hydrogen and another part that is deficient in hydrogen. When coal is heated, two types of pyrolytic debris are formed. One is hydrogen-rich pyrolysis fragments, and the other is hydrogen-poor pyrolysis fragments. Hydrogen is transferred from hydrogen-rich fragments to hydrogen-depleted fragments. The hydrogen transfer reduces the molecular weight of the pyrolysis fragments and stabilizes them.

(2) Transfer of hydrogen from the hydrogen donor component in the solvent

(3) Indirect transfer of hydrogen

Dissolve hydrogen gas in a solvent. The solvent is hydrogenated in the presence of a liquefaction catalyst and converted from non-hydrogen-donating properties to hydrogen-donating properties to induce hydrogen transfer. This type of transfer is an indirect transfer.

Therefore, in a coal liquefaction reaction, the amount of debris produced by coal thermal decomposition must be balanced with the amount of hydrogen transferred to the debris. If the reaction proceeds at a temperature and pressure that breaks the equilibrium, insufficient hydrogen production is required to transfer into the fragments, and the reverse reaction of coal liquefaction occurs. Once the reverse reaction occurs, the solvent recycled into the coal slime during the liquefaction process is intercepted by the reaction system, which reduces the yield of liquefied oil as a product. Simultaneous yield reduction reduces the amount of liquefied oil produced below the amount of recycled solvent, and the solvent (liquefied oil) cannot be recycled. In some cases, coking of the slurry may occur at some point. In this case, a coke layer forms on the inner surface of the reactor wall, making operation of the liquefaction plant difficult.

For the above reasons, it is evident in the prior art that when the reaction temperature is 400 to 480° C., the liquefaction reaction is inevitably carried out at a high pressure of 100 to 300 atm.

However, according to the research results of the present inventors, when the target product of the liquefaction method is solvent refined coal (SRC) and when the liquefaction reaction is performed to produce a large amount of SRC and liquefied oil, it is found that even if the reaction pressure is low, The temperature reduces the amount of hydrogen transferred allowing the reaction to proceed efficiently.

Therefore, according to the present invention, even when the coke oven gas containing 50 to 60 vol% hydrogen is used as the hydrogen source for the reaction, the liquefaction reaction does not need to be carried out at a particularly high reaction pressure, and the reaction pressure is 20 to 200 atm, which is very low pressure area.

The reaction temperature is determined to be in a region where the rate of hydrogenation of the solvent exceeds the rate of hydrogen transfer from the solvent to the fragments produced by thermal decomposition of the coal. However, in certain temperature regions, due to the application of the catalyst, the amount of hydrogen gas entering the solvent becomes greater than the amount of hydrogen gas transferred from the solvent to the pyrolysis fragments.

Therefore, even in the reverse reaction temperature region where coal liquefaction occurs, the catalyst generally accelerates the liquefaction reaction. Consequently, the temperature at which the liquefaction reaction takes place is shifted towards considerably higher temperature values. Furthermore, the aforementioned hydrogen transfer equilibrium extends the reaction temperature range towards low temperature values. The invention can carry out the liquefaction reaction in a wide temperature range from 350 to 480° C., so that the operation of the liquefaction device becomes easy.

In the present invention, the ratio of solvent to coal is calculated on a dry, ash-free basis.

Various types of coal are suitable for use in the present invention. Bituminous coal, sub-bituminous coal, and lignite may be mentioned. Bituminous coal can be caking coal or non-caking coal. Non-caking coals, which are of lower coal rank than bituminous coal, are more preferred and are more economical general purpose coals. The particles of the coal powder are about 20 to 300 mesh, more preferably about 60 to 80 mesh.

The liquefied oil produced and separated in the subsequent process is recycled as a solvent in the liquefaction process. The weight ratio of coal to solvent ranges from 100/100 to 100/233, preferably from 100/100 to 100/170. When the ratio of coal to solvent is lower than 100/100, the viscosity of coal slime increases rapidly, and the operation of the liquefaction unit becomes difficult. When the ratio of coal to solvent exceeds 100/233, the recirculation amount of the solvent increases, and at the same time, the production cost of the liquefied product increases, which is disadvantageous.

It is a characteristic of the present invention that the catalyst is applied to the liquefaction reaction of coal slime. An iron catalyst was used as the catalyst. It is preferred to add sulfur to the iron catalyst. Pyrite, which contains iron and sulfur, can also be used as a catalyst. As described below, the role of the catalyst is to hydrogenate the solvent by hydrogen dissolved in the solvent, hence the term hydrogenation. The amount of catalyst used is represented by the weight ratio of coal to catalyst in the range of 100/0.5 to 100/10, more preferably 100/0.5 to 100/4. When the coal-to-catalyst ratio is lower than 100/0.5, the efficiency of the hydrogen transfer reaction decreases causing the reverse reaction. When the ratio of coal to catalyst exceeds 100/10, the consumption of expensive catalyst increases, which increases the production cost of the liquefied product, and at the same time increases the ash content in solvent refined coal (SRC), thereby reducing the quality of the product.

When the liquefaction reaction is performed by mixing a high-calorie reagent with coal slime, the yield of liquefied products increases due to the generation of hydrocarbons formed by thermal decomposition and enhanced coal conversion. High caloric reagent is the general material name for liquid or gaseous hydrocarbons formed by thermal decomposition, such as heavy oils and plastics. Heavy oils are high boiling residues such as heavy oils from coal and heavy oils from petroleum. Plastics include formed polymer products such as polystyrene, polypropylene, polyethylene and polyvinyl chloride or their wastes (waste plastics) and the like.

For example, when the liquefaction reaction is carried out by blending heavy oils, the yield of light oils increases to easily ensure solvent recycling. The heavy oil added is adjusted so that the weight ratio of solvent to heavy oil is about 100/5 to 100/20. When the ratio of solvent to heavy oil is less than 100/5, the above-mentioned advantages will be weakened, and the amount of heavy oil added will be significantly less. When the ratio exceeds 100/20, the production cost will increase, which is unfavorable. Especially when heavy oil derived from petroleum is added in excess of the above ratio, the paraffin component derived from the heavy oil increases in the produced SRC and causes coking to lower the quality of the product, which is also disadvantageous.

Energy is saved when the liquefaction reaction is carried out by adding plastic. Since the thermal decomposition of plastic is an endothermic reaction, a large amount of energy is required. However, the thermal decomposition of the plastic proceeds simultaneously with the liquefaction reaction, and the plastic can be thermally decomposed by the heat generated by the coal liquefaction reaction. When the plastic is polystyrene, it is prone to thermal decomposition. Polyethylene and polypropylene are not easily thermally decomposed, so some of them are expected to remain as residues. If the decomposition process is carried out only together with coal liquefaction, the residue has no adverse effect on the operation of the plant because the residue is discharged together with the SRC. The addition ratio of plastics varies with the types of plastics. The preferred upper limit of the added plastic is about 100/25 in terms of the weight ratio of coal to plastic, when the ratio exceeds 100/25, the hydrogen consumption of the liquefied plastic will increase, and at the same time the hydrogen used for coal liquefaction becomes insufficient, thus causing reverse reaction.

Secondly, the coal slime is liquefied in the presence of hydrogen, which can be coke oven gas or hydrogen-rich coke oven gas. The hydrogen concentration is 45 to 80 vol%, preferably 50 to 80 vol%. The volume added as hydrogen gas ranges from 0.1 to 2 Nm ³ , more preferably from 0.2 to 1 Nm ³ per 1 kg of coal slime.

The reaction temperature is preferably 350 to 480°C. When the reaction temperature is lower than 350° C., the reaction rate decreases, and the coal liquefaction conversion rate (conversion rate of coal to liquefied products) decreases. When the reaction temperature exceeds 480° C., the reverse reaction to coal liquefaction dominates the reaction system, and at the same time, the operation of the plant becomes difficult. Although the above temperature range allows the liquefaction reaction to proceed, a more preferable temperature range is 390 to 420°C.

As for the reaction pressure, it is preferably 20 to 200 atm. When the reaction pressure is lower than 20atm, the amount of hydrogen in the gas phase is too small relative to the amount of coal, and the reverse reaction of the coal liquefaction reaction dominates the reaction system. When the reaction pressure exceeds 200 atm, the investment cost increases significantly, which is not favorable. The reaction pressure range is more preferably 30 to 100 atm. The reaction pressure may depend only on hydrogen, but a mixed gas containing other gas components is usually used. Other gas components may be nitrogen, carbon monoxide, carbon dioxide and gaseous hydrocarbons such as methane, ethane and ethylene.

Preferred reaction times range from 10 to 120 minutes. The reactor can be a conventional tubular reactor, and the stirring can be performed by blowing gas (coke oven gas).

The liquefied product produced in the liquefaction reaction is separated into liquefied slurry and gas, which exists in the gas phase at a pressure of 20 to 200 atm and a temperature of 300 to 400°C. The gas is mainly composed of hydrogen, carbon monoxide, methane, ethane, ethylene, nitrogen, carbon dioxide and water vapour.

The separated liquefied slurry is processed by vacuum distillation to separate liquefied oil and solvent refined coal. The preferred conditions for distillation are a temperature of 300 to 350°C and a pressure of 1 to 5 Torr. The catalyst is retained in the solvent cleaned coal. Typically the yield of solvent refined coal thus produced ranges from 50 to 90%, more preferably from 70 to 85%, based on the amount of coal (including ash and water content).

For liquefied oils, the amount of solvent that must be recycled as slime. Residual solvent is removed from the system for efficient use.

Fig. 1 is a flow chart of an embodiment of the present invention, coal powder, liquefied oil (solvent) and liquefaction catalyst recycled in subsequent steps are added to a coal slime tank 1. These materials are stirred and mixed in the slime tank 1 to prepare slime.

The coal slime is pressurized by the slurry pump and fed into the reactor 3 through the preheater 2. As a hydrogen source for the liquefaction reaction, coke oven gas or hydrogen-rich coke oven gas is pressurized to a specified pressure by compressor 7 and added to the coal slime before the slurry enters preheater 2 and reactor 3 . The hydrogen-rich treatment of coke oven gas can be one of the following two treatment methods. One is to make the coke oven gas undergo the methane conversion reaction represented by the equation (1), and then make it undergo the replacement reaction represented by the equation (2). The second is to separate coke oven gas with membrane to enrich hydrogen.

(1)

(2)

The coal slime mixed with coke oven gas is reacted in a reactor at a temperature of 350 to 480° C. and a pressure of 20 to 20 atm. During the predetermined residence time, the slime is turned into a gas and a liquefied slurry (which is a mixture of liquefied oil and unliquefied matter). These liquefied products are sent to the gas separator 4 .

The gas separator 4 separates the liquefied product into liquefied slurry and gas. The gas is refined in the gas purification unit 6, and then used as a hydrogen source by being recycled into the reaction system, or removed outside the reaction system.

When the pressure in the reactor 3 is 30 atm or more, the purified gas is fed into the gas expander 8, which is connected to the compressor 7 through the line 30. When the purified gas is used as the power to drive the compressor, its pressure is reduced to close to atmospheric pressure and returned to the coke oven gas supply system to be used as fuel gas and raw materials for chemical reagents, which are common. When the reaction pressure is lower than 30 atm, the purified gas is removed through line 31 and the pressure is reduced to near atmospheric pressure, and then sent back to the coke oven gas supply system.

The liquefied slurry was passed through a pressure reducing valve to reduce the pressure to atmospheric pressure, and then fed into the distillation column 5 while containing insoluble organic matter and ash without being filtered. For the liquefied oil distilled from the distillation column 5, a part of it becomes a light oil product, and the rest is recycled into the slurry tank 1. From the bottom of the distillation column, solvent refined coal (SRC) containing insoluble organic matter and ash is discharged. SRC is used as coking coal to produce high quality coke.

Figure 2 shows another embodiment of the invention. Units and devices having the same functions as in FIG. 1 have the same reference numerals in both figures, and thus explanations thereof are omitted. According to this embodiment, high calorific substances such as heavy oil and melted waste plastics are pressurized in another step and added to the reaction system via line 20 to mix with the coal slime before entering the preheater. The coal slime mixed with high heat is sent into the reactor 3 through the preheater 2 . In Reactor 3, the coal liquefaction reaction starts while heavy oil and waste plastics are thermally decomposed. The thermal decomposition products are mixed into the liquefaction slurry, gas and coal liquefaction products before being discharged from the reactor.

When heavy oil and waste plastic are mixed with coal slime at the same time, the heated and pressurized heavy oil can be input through the feed pipeline, while the melted and pressurized waste plastic is input through another pipeline.

Example 1

Conventional coal was liquefied as described in Figure 1 below. Coke oven gas that was not hydrogen-enriched was used as the hydrogen source. The composition of coke oven gas is shown in Table 1 below.

Table 1

Unit: vol%

H ₂ 56

CH ₄ 28

C ₂ H ₄ 3

CO 7

CO ₂ 3

N ₂ 3

General purpose coal (crushed to 100% 80 mesh, 8.26% ash and 2.75% water on a dry basis) was fed into the slurry tank 1 at a rate of 112 kg/hour. The liquefied oil (recycled solvent) produced in the distillation column 5 was fed into the tank at a rate of 150 kg/hour. Natural pyrite (FeS ₂ ) was fed into the tank as a catalyst at a rate of 3 kg/hour. These components were mixed with each other under stirring to prepare coal slime. In this way, a slurry with a weight ratio of coal (calculated on an ash-free dry basis)/solvent/catalyst of 100/150/3 was obtained.

The slime is pressurized to 100 atm. The coke oven gas was pressurized to 100 atm, and fed into the slurry at a rate of 100 Nm ³ /hour and mixed at the inlet of preheater 2. The mixture of coal slime and coke oven gas is heated in preheater 2. And coke oven gas pressurized to 100 atm was added to the mixture at a rate of 65 Nm ³ /hour and further mixed. This mixture was then added to reactor 3 to carry out liquefaction reaction under the conditions of 440° C. and 100 atm, and the residence time was 20 minutes.

The experimental conditions and results are shown in Table 2. Liquefied oil was produced from the distillation column 5 at a rate of 156 kg/hour, and the liquefied oil was recycled to the slime tank 1 at a rate of 150 kg/hour as a recycled solvent. 6 kg/h of light oil was thus obtained as product.

From the bottom of distillation column 5, SRC was produced at 86 kg/hour. The SRC contained 15.1 wt% insoluble organic matter and 14.0 wt% ash. Due to the low content of insoluble organic matter, SRC can be used as coking coal for the production of high-quality coke.

After the experiment was completed, the reactor 3 was opened to check the surface of the inner wall, and it was found that there was no slime coking.

Example 2

The coal liquefaction reaction was carried out under the same conditions as in Example 1, except that the reaction temperature was 410°C. The experimental conditions and results are shown in Table 2.

As can be seen from Table 2, the experiment of Example 2 provided light oil as product at 15 kg/hour and SRC containing liquefaction catalyst, ash and insoluble organic matter at 82 kg/hour.

The SRC contained 8.5 wt% insoluble organic matter and 14.6 wt% ash. The SRC thus prepared contained less organic matter than the SRC prepared in Example 1. Therefore, the produced SRC is more preferred for use as coking coal to produce high quality coke.

Also in this experiment, no coal slime coking was found on the inner wall surface of the reactor 3.

Example 3

The coal liquefaction reaction was carried out under the same conditions as in Example 2, except that the reaction temperature was 400° C., the reaction pressure was 30 atm, and the residence time was 60 minutes. The experimental conditions and results are given in Table 2.

The experiment of Example 3 provided light oil as product at 9 kg/hour and SRC containing liquefaction catalyst, ash and insoluble organic matter at 86 kg/hour.

The SRC contained 12.8 wt% insoluble organics and 14.0 wt% ash. The SRC thus prepared contained less organic matter than the SRC prepared in Example 1. Therefore, SRC is more preferred for use as coking coal to produce high quality coke.

Also in this experiment, no coal slime coking was found on the inner wall surface of the reactor 3 .

Example 4

The coal liquefaction reaction was carried out under the following conditions: reaction temperature 400°C, pressure 70atm, residence time 60 minutes, coal input rate 138kg/hour (ash input rate 11.1kg/hour, water content input rate 3.7kg/hour), solvent input rate 123kg/hour, that is, the ratio of coal (according to ash-free dry basis) to solvent is 1/1. As a liquefaction catalyst, natural iron ore was input at 4 kg/hour. The experimental conditions and results are shown in Table 2.

The experiment of Example 4 provided light oil as product at 3 kg/hour and SRC containing liquefaction catalyst, ash and insoluble organic matter at 117 kg/hour.

The SRC contained 17.9 wt% insoluble organic matter and 12.9 wt% ash. The SRC thus produced can be used as coking coal for the production of high-quality coke.

Although the ratio of coal to solvent was higher than in Comparative Example 3, no coking was found on the surface of the inner wall of Reactor 3.

Example 5

Experiments were performed using a reaction temperature of 390°C. The experimental conditions and results are shown in Table 2.

The experiment of Example 5 provided light oil as product at 9 kg/hour and SRC containing liquefaction catalyst, ash and insoluble organics at 88 kg/hour.

The SRC contained 10.5 wt% insoluble organics and 13.9 wt% ash. The SRC is therefore preferred for use as coking coal to produce high quality coke.

Also in this experiment, no coking was found on the inner wall surface of the reactor 3 .

Example 6

The experiment was carried out according to a procedure similar to that of Example 5, except that the following conditions were used: reaction temperature 420° C., reaction pressure 50 atm, residence time 60 minutes. The experimental conditions and results are shown in Table 2.

The experiment of Example 6 provided light oil as product at 11 kg/hour and SRC containing liquefaction catalyst, ash and insoluble organic matter at 83 kg/hour.

The SRC contained 9.3 wt% insoluble organic matter and 14.8 wt% ash. The SRC thus produced showed a quality similar to that produced in Example 2. Therefore, this SRC is the most preferred for use as coking coal to produce high quality coke.

Also in this experiment, no coal slime coking was found on the inner wall surface of the reactor 3 .

Table 2 Example No. 1 2 3 4 5 6 Reaction conditions temperature(℃) 440 410 400 400 390 420 pressure (atmospheric pressure) 100 100 30 70 70 50 Stay time (minutes) 20 20 60 60 60 60 Raw material input rate Coal (kg/hour) 112 112 112 138 112 112 Solvent (kg/hour) 150 150 150 128 150 150 Catalyst (kg/hour) 3 3 3 4 3 3 Coke oven gas (Nm ³ /hour) 165 165 165 165 165 165 Liquefied oil Total productivity (kg/hour) 156 165 159 126 159 161 Light oil (kg/hour) 6 15 9 3 9 11 SRC Productivity (kg/hour) 86 82 86 117 88 83 Insoluble organic matter (wt.%) 15.1 8.5 12.8 17.9 10.5 9.3 Ash (wt.%) 14.1 14.6 14.0 12.9 13.9 14.8 Quality Evaluation ○ ○ ○ ○ ○ ○ coking in the reactor none none none none none none

The mark (○) in the quality evaluation column of Table 2 indicates that SRC can be used as coking coal for producing high-quality coke, and the mark (×) indicates that SRC cannot be used as coking coal for producing high-quality coke.

Comparative Examples 1 to 4

The experimental method used in Examples 1 to 6 was applied. Liquefaction experiments were performed using coke oven gas and coal of the same composition as used in these examples. Comparative Examples 1 to 3 did not use a catalyst. Comparative Example 4 was performed at elevated reaction temperature or 485°C. Experimental conditions and results are shown in 3.

In Comparative Examples 1 to 3 and Comparative Example 4 in which no catalyst was used, the amount of liquefied oil produced was less than the amount of solvent necessary for recycling as preparation of coal slime, and the solvent recycling operation could not be performed. As a result, light oil was not obtained as a product. In addition, the obtained SRC contains 20 wt% or more of insoluble organic matter, so this SRC is not suitable for use as coking coal for producing high-quality coke. At the same time, coke was deposited on the inner wall surface of the reactor 3, and the reaction temperature was difficult to maintain.

When the results of Comparative Example 1 were compared with those of Example 1, the only difference in the experimental conditions between the two was the presence/absence of catalyst, however, the results were satisfactory in Example 1 and unsatisfactory in Comparative Example 1 . Therefore, it was concluded that the difference was due to the presence/absence of catalyst.

When Comparative Example 4 (in which the reaction temperature was raised to 485° C.) was compared with Example 1, the difference in experimental conditions between the two was only the reaction temperature. However, the result was satisfactory in Example 1 and unsatisfactory in Comparative Example 4. In the experiment of Comparative Example 4, an excessively high reaction temperature should cause a reverse reaction with respect to the coal liquefaction reaction.

table 3 Comparative Example No. 1 2 3 4 Reaction conditions temperature(℃) 440 410 400 485 pressure (atmospheric pressure) 100 100 70 100 Stay time (minutes) 20 20 20 20 Raw material addition rate Coal (kg/hour) 112 126 126 112 Solvent (kg/hour) 150 138 138 150 Catalyst (kg/hour) - - - 3 Coke oven gas (Nm ³ /hour) 165 165 165 165 Liquefied oil Total production rate (kg/hour) 123 127 140 117 Light oil (kg/hour) 0 0 0 0 SRC Production rate (kg/hour) 122 117 105 119 Insoluble organic matter (wt.%) 24.6 23.7 21.9 27.1 Ash (wt.%) 7.3 8.6 8.6 10.3 Quality Evaluation x x x x coking in the reactor pressure

Example 7

The experimental setup used in Example 1 was employed. Liquefaction experiments were performed in the presence of high calorific substances. The added coke oven gas and coal had the same composition as used in Example 1 (shown in Table 1).

The rate at which the components are added to Reactor 3 is: coal 101 kg/hour (ash 8.1 kg/hour on a dry basis, water content 2.7 kg/hour), recirculated solvent 135 kg/hour, used as a stream of heavy oil in petroleum refining 27kg/hour of liquefied catalytic cracking residue, 3kg/hour of natural pyrite as a liquefaction catalyst, or a weight ratio of coal (on an ash-free dry basis)/recycled solvent/heavy oil of 100/150/30. The coal liquefaction reaction was carried out under the same conditions as in Example 2 (reaction temperature 410° C., reaction pressure 100 atm, residence time 60 minutes). The results are shown in Table 4.

As can be seen from Table 4, the experiment of Example 7 provided 164 kg/hour of liquefied oil from the distillation column, which contained 29 kg/hour of light oil as a product. The other part of the liquefied oil was recycled into the slime tank 1 as a solvent at a rate of 135 kg/hour. From the bottom of the distillation column 5, SRC containing insoluble organic matter and ash was obtained at 5.76 kg/hour. The SRC contained 14.1 wt% insoluble organic matter and 10.7 wt% ash.

The amount of light oil and SRC thus produced as products was compared with the amount produced in Example 2 (carried out under the same conditions as in Example 7), and the following results were found: In Example 2, light oil was mixed with The weight ratio of the added coal (on an ash-free dry basis) was 15%, and the weight ratio of SRC (excluding ash and insoluble organic matter) to the added coal was 63.1%. However, in Example 5, the ratio of light oil was 32.2%, and the ratio of SRC was 63.4%. In other words, Example 7, in which heavy oil was added, gave a higher yield of light oil than Example 2, in which no heavy oil was added, and Example 7 obtained solvent more easily than Example 2.

Example 8

The experiments were carried out under the conditions given in Table 4. The rate at which each component is added to the reactor is: coal 90kg/hour (according to dry basis weight, ash 7.2kg/hour, water content 2.4kg/hour), recirculation solvent 150kg/hour, waste plastics (1/1/1 Polyethylene/polypropylene/polystyrene mixture) 20kg/hour, natural pyrite as liquefaction catalyst 3kg/hour or 80/20/150 weight ratio of coal (on ash-free dry basis)/waste plastics/recycling solvent. The simultaneous treatment of coal and waste plastics was carried out under the same reaction conditions as in Example 2. The results are shown in Table 4.

From the distillation column, liquefied oil was obtained at 176 kg/hour, which included 26 kg/hour of light oil as a product. SRC including insoluble organic matter and ash was obtained from the bottom of the column at 72 kg/hour. The SRC included 12.6 wt% insoluble organics and 10.0 wt% ash.

The amount of light oil and SRC as the product is compared with that produced in Example 2 (using the same conditions as in Implementation 7). The results were 15% light oil and 63.1% SRC in Example 2 and 32.3% light oil and 69.3% SRC in Example 8. In other words, Example 8, in which plastic was added to the reaction system, gave a high yield of light oil, and easily ensured the necessary recycle solvent amount.

Example 9

Carry out the treatment of coal, waste plastics and heavy oil simultaneously under the same condition as embodiment 2, difference is that each component adds the rate of reactor to be: coal 90kg/hour (ash 7.2kg/hour by dry basis weight, water content 2.4kg/hour), recycled solvent 150kg/hour, waste plastic (a mixture of 1/1/1 polyethylene/polypropylene/polystyrene) 10kg/hour, heavy oil 15kg/hour, natural yellow as a liquefaction catalyst Iron ore 3kg/hour or coal with a weight ratio of 80/10/150/15 (calculated on an ash-free dry basis)/waste plastic/recycled solvent/heavy oil. The obtained results are shown in Table 4.

Liquefied oil including 33 kg/hour of light oil as a product was obtained at 183 kg/hour, and SRC including insoluble organic matter and ash was obtained at 71 kg/hour. The SRC included 12.8 wt% insoluble organics and 14.4 wt% ash.

The ratio of light oil and SRC to coal added (based on ashless dry basis weight) produced in Example 9 was 41.0% for light oil and 64.3% for SRC compared to 15 for light oil in Example 2 %, 63.1% for SRC (excluding ash and insoluble organic matter). In other words, compared with Example 2 in which no heavy oil or waste plastic was added to the reaction system, the yield of light oil in Example 9 increased. Therefore, it was demonstrated that Example 9 easily secured the necessary recycled solvent amount.

Table 4 Example No. 7 8 9 Reaction conditions temperature(℃) 410 410 410 pressure (atmospheric pressure) 100 100 100 Stay time (minutes) 60 20 20 Raw material input rate Coal (kg/hour) 101 90 90 Heavy oil (kg/hour) 27 - 15 Waste plastic (kg/hour) - 20 10 Solvent (kg/hour) 135 150 150 Catalyst (kg/hour) 3 3 3 Coke oven gas (Nm ³ /hour) 165 165 165 Liquefied oil Total production rate (kg/hour) 164 176 183 Light oil (kg/hour) 29 26 33 SRC Production rate (kg/hour) 76 72 71 Insoluble organic matter (wt.%) 14.1 12.6 12.8 Ash (wt.%) 10.7 10.0 14.4 Quality Evaluation ○ ○ ○ coking in the reactor none none none

According to the invention, particularly inexpensive coke oven gas is used as the hydrogen source for the liquefaction reaction, so that the production costs of the liquefied product are significantly reduced.

In addition, the liquefaction reaction can be carried out at a reaction temperature of 350 to 480° C. and a reaction pressure of 20 to 200 atm. Since the reaction conditions include a low-temperature region and a low-pressure region, investment costs and operating costs are reduced, and the production cost of liquefied products is further reduced.

Meanwhile, when heavy oil is mixed with plastics and liquefied together with coal, the thermal decomposition of these materials produces hydrocarbons and the conversion of coal increases, which increases the yield of liquefied products, thereby reducing the production cost of liquefied products.

Claims (6)

1. A method for coal liquefaction, comprising the steps of: (a) produce coal slime by coal powder, solvent and catalyst, by 100 weight parts of coal, described solvent is 100 to 233 weight parts, and described catalyst is 0.5 to 10 weight parts; (b) mixing a high-calorie substance into the coal slime of step (a), wherein the high-calorie substance generates liquid or gaseous hydrocarbons by thermal decomposition; (c) reacting the coal slime and coke oven gas at a temperature of 350 to 480° C. and a pressure of 20 to 200 atm to form a liquefied product; (d) separating the liquefied product into liquefied slurry and gas; (e) Distilling liquefied slurries to form liquefied oil and solvent refined coal; (f) recycling said liquefied oil as a solvent in step (a). 2. The method of claim 1, wherein the high-calorie substance is heavy oil, and the amount of the heavy oil is 5-20 parts by weight, based on 100 parts by weight of solvent. 3. The method of claim 1, wherein the high calorie substance is plastic in an amount of up to 25 parts by weight based on 100 parts by weight of coal. 4. The method of claim 1, wherein the catalyst is pyrite. 5. The method of claim 1, wherein the distillation in step (e) is carried out at a temperature of 300 to 350°C and a pressure of 1 to 5 Torr. 6. The method of claim 1, wherein the temperature in step (c) is 390 to 420°C, and the pressure in step (b) is 30 to 100 atm.

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