CN102703150A - Dual-fluidized bed low-concentration methane concentrating method and system thereof - Google Patents

Abstract

The invention discloses a double fluidized bed low-concentration methane concentration method. First, the low-concentration methane is adsorbed in a bubbling fluidized bed adsorption reactor; After desorption, it enters the cyclone separator; finally, the gas and solid are separated in the cyclone separator, and the adsorbent particles enter the bubbling fluidized bed adsorption reactor to be reused; the mixed gas composed of water vapor and methane enters the condensation separator for separation, and the high Concentrations of methane are separated. At the same time, the invention also discloses a double fluidized bed low-concentration methane concentration system. The invention adopts high-pressure adsorption and high-temperature desorption methods in bubbling fluidized bed adsorption reactors and fast bed desorption reactors with different functions to realize the concentration and purification of methane in low-concentration coalbed methane, and at the same time realize the efficient use and environmental protection.

Description

Method and system for concentrating low-concentration methane in double fluidized beds

technical field

The invention relates to a method and system for concentrating low-concentration methane, which is mainly suitable for concentrating and purifying low-concentration coal-bed methane and other gases containing low-concentration methane.

Background technique

With the continuous growth of energy demand, the development and utilization of distributed low-grade energy has become one of the main ways to save energy and solve the current energy crisis, and the widely distributed and abundant coalbed methane resources provide a reliable gas source guarantee. my country's coalbed methane resources are about 36.7 trillion cubic meters, which is equivalent to natural gas reserves and ranks third in the world. According to calculations, 1,000 cubic meters of coal-bed methane is equivalent to 1 ton of standard coal. Based on this, it is estimated that my country's coal-bed methane reserves are equivalent to 35 billion tons of standard coal or 24 billion tons of oil.

At present, coalbed methane with a methane concentration higher than 35% can be directly used as fuel. However, the part where the methane concentration is lower than 30% is often not effectively utilized, but is directly diluted and discharged into the atmosphere. The coalbed methane emitted into the atmosphere not only causes a huge waste of energy, but also aggravates air pollution and greenhouse effect. The GWP (Global Warming Potential) of a unit mass of methane on the atmospheric greenhouse effect is 21.5 times that of carbon dioxide, and its ability to destroy the ozone layer is 7 times that of carbon dioxide. Therefore, the comprehensive and effective utilization of low-concentration coalbed methane has important economic and environmental significance for improving and optimizing the energy structure and reducing air pollution.

The methane content in low-concentration coalbed methane is often lower than 30%, and the methane content in mine exhaust gas is even lower than 1%, and the production volume fluctuates greatly, and the distribution of storage volume is scattered. If the pipeline transportation system is used for distribution, the economic cost will be high, and Inconvenient to maintain. Therefore, the industry often separates and concentrates this low-concentration coalbed methane that cannot be directly transported long-distance and used as civil and industrial raw materials, so as to realize safe, convenient and economical long-distance transportation.

For the concentration of low-concentration methane gas, there are mainly the following methods: low-temperature cryogenic separation method, membrane separation method and adsorption-desorption method. Among them, the low-temperature cryogenic separation method has a high concentration of gas and methane, but the device is complicated and the equipment investment is large. Impurities such as C0 ₂ and water are easy to block the pipeline during low-temperature rectification and must be removed first, so the process is complicated; although the membrane separation technology has simple equipment , The operation investment is small, but it is still in the experimental stage, and there is still a big gap from industrial application; the adsorption-desorption method includes two processes of adsorption and desorption regeneration, that is, the use of boosting (or cooling) and depressurization (or heating) to achieve Adsorption and desorption separation process for methane. The adsorption-desorption method has the advantages of low energy consumption, low cost of adsorbent, low initial investment, short operation period, and large gas treatment capacity. Therefore, the technology of enriching low-concentration coalbed methane by adsorption-desorption method is relatively mature. At present, the research on the adsorption-desorption method mainly focuses on the concentration of methane by pressure swing adsorption in the tower. In order to ensure the continuous concentration and purification of methane, multiple sets of adsorption towers are often required to work alternately, which not only increases the equipment investment, but also increases the occupied area.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, one of the purposes of the present invention is to provide a dual-fluidized-bed low-concentration methane concentration method that realizes high-efficiency utilization of coalbed methane in mining areas and environmental protection.

The second object of the present invention is to provide a dual-fluidized-bed low-concentration methane concentration system with simple structure and low investment cost.

One of purpose of the present invention is achieved through the following technical solutions:

A method for concentrating low-concentration methane in double fluidized beds, the method comprising the steps of:

A. Input the coalbed methane containing low concentration methane into the bubbling fluidized bed adsorption reactor, so that the adsorbent particles in the bubbling fluidized bed adsorption reactor are in a bubbling fluidized state, and the low concentration methane is in the bubbling flow Under the pressure of 0.3~0.7MPa in the fluidized bed adsorption reactor, it is adsorbed by the adsorbent particles, and the adsorbed coal bed gas is discharged out of the bubbling fluidized bed adsorption reactor through the back pressure valve; the coal bed gas with low concentration of methane is methane Coalbed methane with a volume content of 1~30%;

B. Part of the adsorbent particles fall to the J-type return valve under the action of bubbling fluidization state, and water vapor is introduced into the J-type return valve as the fluidization loosening wind. Under the action of the fluidization loosening wind, the J-type return valve The adsorbent particles in the feed valve fall into the fast bed desorption reactor; the outer wall of the fast bed desorption reactor is provided with an electric heater, and water vapor is introduced into the fast bed desorption reactor as fluidizing wind to make the fast bed desorption reactor The bed desorption reactor is under the condition of 200~400℃; the adsorbent particles are desorbed in the fast bed desorption reactor; , taken out of the fast bed desorption reactor through the riser, and enters the cyclone separator;

C. After gas-solid separation in the cyclone separator, the desorbed adsorbent particles fall to the adsorbent cooling device. In the adsorbent cooling device, the adsorbent particles are cooled by circulating water, and the cooled adsorbent particles After entering the absorbent storage through the regulating valve, the amount of solid adsorbent particles entering the bubbling fluidized bed adsorption reactor is controlled by adjusting the particle control valve at the lower part of the absorbent storage, so that the particles entering the bubbling fluidized bed adsorption reactor The solid adsorbent particles in the filter are reused; the mixed gas composed of water vapor and methane separated by the cyclone separator enters the condensation separator, and the mixed gas is cooled by circulating water in the condensation separator, and the water vapor is condensed into liquid water , methane is separated after cooling to form a high-concentration methane product.

As a preferred solution of the present invention, the bubbling fluidized bed adsorption reactor is divided into two parts, the left and the right, by the vertically arranged material dividing plate inside, and the particle control valve is located on the right side of the bubbling fluidized bed adsorption reactor. Above the part, the J-type return valve is located below the left part of the bubbling fluidized bed adsorption reactor.

Two of the purpose of the present invention is achieved through the following technical solutions:

Double fluidized bed low concentration methane concentration system, including bubbling fluidized bed adsorption reactor, J-type return valve, fast bed desorption reactor, riser, cyclone separator, adsorbent cooling device, regulating valve, adsorbent storage, particle control valve, condensation separator and steam generator; the bubbling fluidized bed adsorption reactor is filled with adsorbent particles, and the outer wall of the fast bed desorption reactor is provided with an electric heater; the bubbling The fluidized bed adsorption reactor is connected with the fast bed desorption reactor through the J-type return valve, and the fast bed desorption reactor is connected with the cyclone separator through the riser, and the bottom outlet of the cyclone separator is connected with the adsorbent cooling device. The inlet is connected, the outlet of the adsorbent cooling device is connected with the inlet of the adsorbent storage through a regulating valve, and the outlet of the adsorbent storage is connected with the bubbling fluidized bed adsorption reactor through a particle control valve; the cyclone separator The top gas outlet is connected to the condensing separator, the gas outlet of the condensing separator is a high-concentration methane output port, the liquid outlet of the condensing separator is connected to the inlet of the steam generator, and the outlet of the steam generator is respectively connected to the J-type The return valve is connected with the fast bed desorption reactor.

As a preferred solution of the present invention, the adsorbent cooling device adopts a circulating water cooler.

As another preferred solution of the present invention, the gas outlet of the condensation separator is filled with a solid desiccant.

As yet another preferred solution of the present invention, the particle size of the adsorbent particles is 300-600 μm.

As an improvement of the present invention, the condensation separator adopts a circulating water cooler.

As another improvement of the present invention, the gas outlet of the bubbling fluidized bed adsorption reactor is provided with a back pressure valve.

Compared with the prior art, the dual-fluidized-bed low-concentration methane concentration method and system thereof of the present invention have the following advantages:

1. The present invention adopts adsorbent particles to adsorb low-concentration methane, and adopts high-pressure adsorption and high-temperature desorption methods in bubbling fluidized bed adsorption reactors and fast-bed desorption reactors with different functions to realize the desorption of low-concentration coalbed methane. The concentration and purification of methane simultaneously realize the efficient utilization of coalbed methane in mining areas and environmental protection.

2. The system is mainly completed by two reactors with different functions, a bubbling fluidized bed adsorption reactor and a fast bed desorption reactor, with simple structure and low investment cost.

3. Using superheated steam as the fluidization gas of the fast bed desorption reactor can effectively avoid the adsorption of water vapor by the adsorbent under certain high temperature conditions; Methane reacts; water vapor and methane are easily separated.

Description of drawings

Figure 1 is a schematic diagram of the structure of a dual-fluidized-bed low-concentration methane concentration system.

In the figure: 1—fast bed desorption reactor; 2—electric heater; 3—riser; 4—cyclone separator; 5—adsorbent cooling device; 6—regulating valve; 7—adsorbent storage; 8— Particle control valve; 9—back pressure valve; 10—bubbling fluidized bed adsorption reactor; 11—material distribution partition; 12—J-type return valve; 13—condensation separator; 14—steam generator.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

The method for concentrating low-concentration methane in double fluidized beds comprises the following steps: A. Inputting coal bed gas containing low-concentration methane into a bubbling fluidized bed adsorption reactor 10, as shown in FIG. 1 . The adsorbent particles in the bubbling fluidized bed adsorption reactor 10 are in a bubbling fluidized state, and the low-concentration methane is adsorbed by the adsorbent particles under the pressure of 0.3-0.7 MPa in the bubbling fluidized bed adsorption reactor 10 , the adsorbed coalbed methane that does not contain or contains less methane is discharged from the bubbling fluidized bed adsorption reactor 10 through the back pressure valve 9 . Coalbed methane with low concentration of methane is coalbed methane with a methane volume content of 1-30%.

B. Part of the adsorbent particles (mainly referring to adsorbent particles with high methane density) fall to the J-type return valve 12 under the action of bubbling fluidization state, and water vapor is passed into the J-type return valve 12 as Fluidization loosening wind, under the action of fluidization loosening wind, the adsorbent particles in the J-type return valve 12 fall into the fast bed desorption reactor 1 . An electric heater 2 is installed on the outer wall of the fast bed desorption reactor 1, and water vapor is introduced into the fast bed desorption reactor 1 as fluidizing wind, so that the fast bed desorption reactor 1 is under a high temperature condition of 200~400°C Under this condition, the adsorption of water vapor by the adsorbent can be effectively avoided, and at the same time, the reaction between water vapor and methane can be prevented, and water vapor and methane can be easily separated. The adsorbent particles are desorbed in the fast bed desorption reactor 1 . After desorption, part of the adsorbent particles in the fast bed desorption reactor 1 is brought out of the fast bed desorption reactor 1 through the riser 3 under the action of the fluidizing wind, and enters the cyclone separator 4 .

C, after the gas-solid separation is carried out in the cyclone separator 4, the adsorbent particles after desorption fall to the adsorbent cooling device 5, and in the adsorbent cooling device 5, the adsorbent particles are cooled by circulating water, and the cooled adsorbent particles The adsorbent particles enter the absorbent storage 7 after passing through the regulating valve 6, and the amount of solid adsorbent particles entering the bubbling fluidized bed adsorption reactor 10 is controlled by adjusting the particle control valve 8 at the bottom of the absorbent storage 7, so that the The solid adsorbent particles in the bubbling fluidized bed adsorption reactor 10 are recycled. The mixed gas composed of water vapor and methane separated by the cyclone separator 4 enters the condensing separator 13, and the condensing separator 13 uses circulating water to cool the mixed gas, and the water vapor is condensed into liquid water, and the methane is separated after cooling , forming high-concentration methane products.

The bubbling fluidized bed adsorption reactor 10 is divided into left and right parts by a vertically arranged material dividing plate 11, the particle control valve 8 is located above the right part of the bubbling fluidized bed adsorption reactor 10, and the J-type return valve 12 It is located below the left part of the bubbling fluidized bed adsorption reactor 10 . The material distribution partition 11 can prevent the adsorbent particles falling from the particle control valve 8 from directly entering the J-type return sealing valve 12 .

The double fluidized bed low concentration methane concentration system, as shown in Figure 1, includes a bubbling fluidized bed adsorption reactor 10, a J-type return valve 12, a fast bed desorption reactor 1, a riser 3, and a cyclone separator 4 , Adsorbent cooling device 5 (adsorbent cooling device 5 adopts circulating water cooler), regulating valve 6, adsorbent storage 7, particle control valve 8, condensation separator 13 (condensing separator 13 adopts circulating water cooler) and steam generator 14. The bubbling fluidized bed adsorption reactor 10 is filled with adsorbent particles (in this embodiment, the particle size of the selected adsorbent particles is 300-600 μm), and the gas outlet of the bubbling fluidized bed adsorption reactor 10 is provided with a back pressure valve 9. An electric heater 2 is installed on the outer wall of the fast bed desorption reactor 1 . The bubbling fluidized bed adsorption reactor 10 is connected with the fast bed desorption reactor 1 through the J-type return valve 12, and the fast bed desorption reactor 1 is connected with the cyclone separator 4 through the riser pipe 3, and the bottom of the cyclone separator 4 The outlet is connected to the inlet of the adsorbent cooling device 5, the outlet of the adsorbent cooling device 5 is connected to the inlet of the adsorbent storage 7 through the regulating valve 6, and the outlet of the adsorbent storage 7 is adsorbed and reacted with the bubbling fluidized bed through the particle control valve 8 Device 10 is connected. The top gas outlet of the cyclone separator 4 is connected to the condensation separator 13, and the gas outlet of the condensation separator 13 is a high-concentration methane output port (the gas outlet is filled with a solid desiccant, and the solid desiccant dries the high-concentration methane), The liquid outlet of the condensation separator 13 is connected to the inlet of the steam generator 14, and the outlet of the steam generator 14 is connected to the J-type return valve 12 and the fast bed desorption reactor 1 respectively.

The dual-fluidized bed low-concentration methane concentration system is used for the concentration and separation of methane in low-concentration coalbed methane. By using an adsorbent capable of adsorbing methane, the adsorption and desorption of methane are respectively performed in the bubbling fluidized bed adsorption reactor 10 and the fast bed desorption reactor 1, so as to realize the concentration and separation of methane.

The working process of the system is as follows: ①Before the system starts to operate, turn on the electric heater 2 to heat the fast bed desorption reactor 1, so as to avoid direct introduction of superheated steam, which may damage the adsorbent due to sudden condensation; If the internal temperature is higher than 100°C, turn off the electric heater 2, and at the same time pass superheated steam to empty the fast bed desorption reactor 1 and the riser 3, so as not to affect the concentration of methane after separation, until it is exhausted air, that is, to complete the preparatory work before the normal operation of the system; at the same time, storing a certain height of adsorbent particles in the adsorbent cooling device 5 can prevent the gas in the bubbling fluidized bed adsorption reactor 10 from leaking. ②When the system is in normal operation, start to feed low-concentration coalbed methane into the bubbling fluidized bed adsorption reactor 10 to carry out the adsorption process. At this time, the adsorbent particles in the bubbling fluidized bed adsorption reactor 10 are under high pressure (0.3 ~0.7MPa) to adsorb methane in coalbed methane, and the adsorbent particles with sufficient density to absorb enough methane settle at the bottom of the bubbling fluidized bed adsorption reactor 10. Large adsorbent particles enter the J-type return valve 12 around the lower end of the material distribution partition 11, and then flow into the fast bed desorption reactor 1. ③In the high-temperature (200~400°C) fast bed desorption reactor 1, methane is desorbed from the adsorbent particles, passes through the riser 3, and after being separated by the cyclone separator 4, the desorbed adsorbent particles enter the adsorbent Cooling in the cooling device 5, the opening and closing of the regulating valve 6 is controlled by the temperature feedback control in the adsorbent cooling device 5, thereby controlling the amount of adsorbent particles entering the adsorbent storage 7, and finally through the particle control valve 8. into the bubbling fluidized bed adsorption reactor 10 for adsorption. ④The high-concentration methane-water vapor mixture separated by the cyclone separator 4 enters the condensation separator 13, which uses circulating water as the coolant, and the cooled condensed water passes through the steam generator 14 to generate superheated water steam. Finally, high-concentration methane gas is obtained from the gas outlet of the condensation separator 13 . During the adsorption process, the pressure in the bubbling fluidized bed adsorption reactor 10 and the total amount of adsorbed particles can be adjusted by adjusting the opening of the back pressure valve 9 and the opening of the particle control valve 8 to meet different operating conditions , to optimize system operating efficiency.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the scope of the claims of the present invention. the

Claims (8)

1. double fluidized bed low-concentration methane enrichment method is characterized in that, the method comprises the steps: A. Input the coal bed gas containing low-concentration methane into the bubbling fluidized bed adsorption reactor (10), so that the adsorbent particles in the bubbling fluidized bed adsorption reactor (10) are in a bubbling fluidized state, low Concentrated methane is adsorbed by the adsorbent particles under the pressure of 0.3~0.7MPa in the bubbling fluidized bed adsorption reactor (10), and the adsorbed coal bed gas is discharged out of the bubbling fluidized bed adsorption reactor through the back pressure valve (9) (10); the low-concentration methane coalbed methane is coalbed methane with a methane volume content of 1-30%; B. Part of the adsorbent particles fall to the J-type return valve (12) under the action of the bubbling fluidization state, and water vapor is passed into the J-type return valve (12) as the fluidization and loosening wind. Under the action, the adsorbent particles in the J-type return valve (12) fall into the fast bed desorption reactor (1); the outer wall of the fast bed desorption reactor (1) is equipped with an electric heater (2), and Water vapor is introduced into the fast bed desorption reactor (1) as fluidized air, so that the fast bed desorption reactor (1) is under the condition of 200~400°C; the adsorbent particles are in the fast bed desorption reactor (1) Desorption occurs inside; after desorption, some adsorbent particles in the fast bed desorption reactor (1) are brought out of the fast bed desorption reactor (1) through the riser (3) under the action of fluidized wind and enter Inside the cyclone separator (4); C. After the gas-solid separation in the cyclone separator (4), the desorbed adsorbent particles fall to the adsorbent cooling device (5), and in the adsorbent cooling device (5), the adsorbent particles are cooled by circulating water After cooling, the cooled adsorbent particles enter the absorbent storage (7) through the regulating valve (6), and enter the bubbling fluidized bed by adjusting the particle control valve (8) at the lower part of the absorbent storage (7). The amount of solid adsorbent particles in the adsorption reactor (10) enables the solid adsorbent particles entering the bubbling fluidized bed adsorption reactor (10) to be reused; the water vapor and The mixed gas composed of methane enters the condensation separator (13), and the mixed gas is cooled by circulating water in the condensation separator (13). The water vapor is condensed into liquid water, and the methane is separated after cooling to form a high-concentration methane product. 2. The double-fluidized-bed low-concentration methane concentration method according to claim 1, characterized in that, the bubbling fluidized-bed adsorption reactor (10) is composed of a vertically arranged dividing partition (11) Divided into left and right parts, the particle control valve (8) is located above the right part of the bubbling fluidized bed adsorption reactor (10), and the J-type return valve (12) is located in the bubbling fluidized bed adsorption reactor (10 ) below the left portion. 3. The double fluidized bed low concentration methane concentration system is characterized in that it includes a bubbling fluidized bed adsorption reactor (10), a J-type return valve (12), a fast bed desorption reactor (1), and a riser (3), cyclone separator (4), adsorbent cooling device (5), regulating valve (6), adsorbent storage (7), particle control valve (8), condensation separator (13) and steam generator ( 14); the bubbling fluidized bed adsorption reactor (10) is filled with adsorbent particles, and the outer wall of the fast bed desorption reactor (1) is provided with an electric heater (2); the bubbling fluidized bed The bed adsorption reactor (10) is connected to the fast bed desorption reactor (1) through the J-type return valve (12), and the fast bed desorption reactor (1) is connected to the cyclone separator (4) through the riser (3) The bottom outlet of the cyclone separator (4) is connected to the inlet of the adsorbent cooling device (5), and the outlet of the adsorbent cooling device (5) is connected to the adsorbent storage (7) through the regulating valve (6) The outlet of the adsorbent storage (7) is connected to the bubbling fluidized bed adsorption reactor (10) through the particle control valve (8); the top gas outlet of the cyclone separator (4) is connected to the condensation separator (13) connection, the gas outlet of the condensing separator (13) is a high-concentration methane output port, the liquid outlet of the condensing separator (13) is connected to the inlet of the steam generator (14), and the steam generator ( The outlet of 14) is respectively connected with the J-type return valve (12) and the fast bed desorption reactor (1). 4. The dual-fluidized-bed low-concentration methane concentration system according to claim 3, wherein the adsorbent cooling device (5) adopts a circulating water cooler. 5. The dual-fluidized-bed low-concentration methane concentration system according to claim 3, characterized in that the gas outlet of the condensation separator (13) is filled with a solid desiccant. 6. The dual-fluidized-bed low-concentration methane concentration system according to claim 3, wherein the particle size of the adsorbent particles is 300-600 μm. 7. The dual-fluidized-bed low-concentration methane concentration system according to claim 3, characterized in that the condensation separator (13) adopts a circulating water cooler. 8. The dual-fluidized bed low-concentration methane concentration system according to claim 3, characterized in that the gas outlet of the bubbling fluidized bed adsorption reactor (10) is provided with a back pressure valve (9).

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