Pulverized coal circulating fluidized bed catalytic gasification device and method

Abstract

The present invention relates to a pulverized coal circulating fluidized bed catalytic gasification device and method, and discloses a device for increasing methane production by pulverized coal circulating fluidized bed catalytic gasification, comprising: a feeder; a fluidized bed pyrolysis furnace connected to the feeder through a feed inclined pipe; a fluidized bed gasification furnace connected to the fluidized bed pyrolysis furnace through a pyrolysis inclined pipe; a fast bed gasification furnace, the lower inlet of which is connected to the upper outlet of the fluidized bed gasification furnace; a fluidized bed combustion chamber, the upper inlet of which is connected to the lower outlet of the fluidized bed gasification furnace; a fine powder settling / stripper connected to the fluidized bed pyrolysis furnace through a gasification inclined pipe. The present invention also discloses a method for increasing methane production by pulverized coal circulating fluidized bed catalytic gasification. The present invention has the characteristics of high carbon conversion rate, high gasification intensity, high pulverized coal utilization rate, wide adaptability of gasified coal types, reasonable energy utilization, and stable and efficient operation of the device.

Description

Technical Field

[0001] The present invention belongs to the field of coal gasification, and relates to a pulverized coal circulating fluidized bed catalytic gasification device and method. Background Art

[0002] Coal, petroleum, and natural gas are the world's three major primary energy sources. Among them, coal accounts for about 79% of the world's energy reserves. Coal is one of the main fuel resources for generating power, heat, coal coking, and by-product tar. China is a country with a mainly coal-based energy structure, which will not change in the next long period. According to statistics, in the primary energy consumption structure of China in 2015, coal accounted for 63.7%. With the increasing shortage of petroleum resources, effectively utilizing coal resources has become a strategy for the sustainable development of China's energy. The reserves of low-rank coal in China account for more than 55% of the total coal resources. However, it has high moisture content and low degree of coalification, and the direct combustion efficiency is low, which not only wastes resources but also pollutes the environment, resulting in the emissions of acid rain, PM2.5, and greenhouse gases such as SOx and NOx. Coal gasification technology is the key technology to realize the clean, efficient, and comprehensive utilization of coal, an important way for coal conversion, and also one of the key technologies for synthesizing chemicals, combined cycle power generation, and coal-based substitute natural gas. Realizing the efficient and clean utilization of coal is the key to the sustainable development of China's energy and an effective way to solve the energy and environmental problems faced globally.

[0003] China is the world's largest application market for coal gasification technology. At present, a variety of coal gasification technologies have been successfully applied industrially. Currently, the more widely used one belongs to the entrained flow gasification technology, which improves the carbon conversion rate at the cost of high temperature and high pressure, bringing problems such as high energy consumption, difficult gas purification, and harsh requirements for equipment. At the same time, the excessively high operating temperature of the entrained flow slag gasification technology increases the investment, maintenance, and operating costs of the entrained flow bed. The research report of the Electric Power Research Institute (EPRI) of the United States points out that the existing industrial entrained flow gasifiers are not suitable for the gasification of high-ash and high-ash fusion point coals, and the world needs industrialized fluidized bed gasification technology. The fluidized bed technology, whether for combustion or gasification, has the nature of adapting to high-ash fusion point and high-ash coal types. The successful combustion of coal gangue by a circulating fluidized bed boiler is evidence.

[0004] Natural gas is a high-quality fuel and an important chemical raw material, with the advantages of safety, reliability, greenness and environmental protection. With the rapid development of China's economy and the acceleration of the urbanization process, the demand for natural gas is increasing day by day. China's own natural gas production cannot meet the demand for natural gas, and the contradiction between supply and demand is becoming increasingly prominent. The supply gap can only be filled by relying on imports, which greatly affects China's energy security. The existing coal-to-natural gas technologies can be divided into two types: the two-step method and the one-step method. The two-step coal-to-natural gas technology belongs to a relatively traditional technology. It first converts coal into syngas (CO + H2), and then carries out methanation to obtain SNG. It needs to go through the following steps: gasification, shift cooling, purification, methane synthesis, etc. The one-step coal-to-natural gas technology directly synthesizes methane from coal, and realizes the gasification, shift and methanation reaction processes through a catalyst in the gasifier to obtain syngas rich in methane. The two-step coal-to-natural gas technology needs to be realized in different reactors, which results in the mismatch of the temperature and pressure of each reaction process. There are more heat losses during the internal circulation of the system, reducing the energy conversion efficiency of the system. The one-step coal-to-natural gas technology effectively solves the above problems, realizes the coupling of logistics and heat, and has high economic efficiency and feasibility. Therefore, it has become an important research direction in the field of coal-to-natural gas.

[0005] US Patent US4077778 proposed a process for the one-step coal-to-methane process, using alkali metal carbonate or alkali metal hydroxide as a catalyst, controlling the reaction temperature in the furnace at about 700 °C through superheated steam, and reacting with pulverized coal under the action of the catalyst to directly obtain methane-rich gas. This process needs to heat the superheated steam to about 850 °C, with high energy consumption and low carbon conversion rate. It is difficult to maintain the reaction temperature without external heat supply, and this technology is still in the research and development stage.

[0006] Chinese Patent CN102021037B proposed a method for the one-step catalytic gasification of coal to methane, dividing the gasifier into a syngas generation section, a coal methanation section and a syngas methanation section, and carrying out combustion, gasification, methanation reaction and pyrolysis reaction in stages. However, multiple air distribution plates and overflow channels need to be set in the gasifier, the internal structure of the furnace is complex, the gasification efficiency and methane yield are low, and the introduction of oxygen at the bottom of the fluidized bed easily causes the ash slag to melt and agglomerate to form large pieces of molten slag, blocking the outlet of the gasifier and the gas distributor, thus affecting the operation stability of the device and there is no industrial device for this technology yet.

[0007] In summary, although the existing coal catalytic gasification technologies have to a certain extent solved the disadvantages of traditional fixed-bed and entrained-flow bed gasification for producing rich-methane synthesis gas, they are all in the R & D or scale-up stage and have not yet been industrialized. Due to the limitations of fluidized bed technology and catalytic process conditions, the carbon conversion rate and gasification intensity are low. Therefore, how to effectively improve the carbon conversion rate and gasification intensity, effectively utilize the heat cascades of combustion, gasification, and pyrolysis, reasonably couple the reaction processes of combustion, gasification, pyrolysis, shift conversion, and methanation, and achieve the efficient and clean utilization of pulverized coal by fractionation in a true sense of pyrolysis-gasification integration is the key to the development of coal gasification technology. Summary of the Invention

[0008] The object of the present invention is to provide a new pulverized coal circulating fluidized bed catalytic gasification device and method for increasing methane production, aiming at the problems of low carbon conversion rate, low gasification intensity, low methane yield, low pulverized coal utilization rate, and difficulty in using low-rank coal existing in the prior art. The present invention has the characteristics of high carbon conversion rate, high gasification intensity, high methane yield, high pulverized coal utilization rate, wide adaptability of gasified coal types, reasonable energy utilization, and stable and efficient operation of the device.

[0009] According to one aspect of the present invention, there is provided a pulverized coal circulating fluidized bed catalytic gasification device for increasing methane production, comprising:

[0010] A feeder;

[0011] A fluidized bed pyrolysis furnace, which is connected to the feeder through a feed inclined pipe;

[0012] A fluidized bed gasification furnace, which is connected to the fluidized bed pyrolysis furnace through a pyrolysis inclined pipe;

[0013] A fast bed gasification furnace, the lower inlet of which is connected to the upper outlet of the fluidized bed gasification furnace;

[0014] A fluidized bed combustion chamber, the upper inlet of which is connected to the lower outlet of the fluidized bed gasification furnace;

[0015] A fine powder settling / stripper, which is connected to the fluidized bed pyrolysis furnace through a gasification inclined pipe.

[0016] According to some embodiments of the present invention, the fluidized bed pyrolysis furnace includes a dense phase region and a dilute phase region from bottom to top.

[0017] According to the preferred embodiments of the present invention, the lower part of the side wall of the dense phase region is respectively provided with a pulverized coal inlet and a gasified semi-coke inlet. The pulverized coal inlet is connected to the feeder through the feed inclined pipe; the gasified semi-coke inlet is connected to the fine powder settling / stripper through the gasification inclined pipe; the middle part of the side wall of the dense phase region is provided with a pyrolyzed semi-coke outlet, which is connected to the fluidized bed gasification furnace through the pyrolysis inclined pipe.

[0018] According to a preferred embodiment of the present invention, a cyclone separator of the fluidized bed pyrolysis furnace is arranged in the dilute phase region for separating the gas generated in the dense phase region.

[0019] According to a preferred embodiment of the present invention, a pyrolysis fluidizing gas inlet is arranged at the bottom of the fluidized bed pyrolysis furnace for receiving pyrolysis fluidizing gas.

[0020] According to a preferred embodiment of the present invention, a pyrolysis gas outlet is arranged at the top of the fluidized bed pyrolysis furnace, which is connected to the gas outlet of the cyclone separator of the fluidized bed pyrolysis furnace for discharging the separated pyrolysis gas.

[0021] According to a preferred embodiment of the present invention, the fluidized bed gasifier and the fluidized bed pyrolysis furnace are arranged side by side.

[0022] According to some embodiments of the present invention, a pyrolytic semicoke inlet is arranged at the lower part of the side wall of the fluidized bed gasifier, which is connected to the fluidized bed pyrolysis furnace through a pyrolysis inclined pipe.

[0023] According to a preferred embodiment of the present invention, a gasifying agent inlet is arranged at the lower part of the side wall of the fluidized bed gasifier for receiving the gasifying agent.

[0024] According to a preferred embodiment of the present invention, the lower outlet of the fluidized bed gasifier is connected to the upper inlet of the fluidized bed combustion chamber.

[0025] According to some embodiments of the present invention, a gas distribution plate is arranged below the interior of the fluidized bed combustion chamber; a slag discharge outlet is arranged at the bottom of the fluidized bed combustion chamber, and the slag discharge outlet is connected to a slag tank.

[0026] According to a preferred embodiment of the present invention, the upper outlet of the fluidized bed gasifier is reduced in diameter and then connected to the lower inlet of the fast bed gasifier.

[0027] According to a preferred embodiment of the present invention, the fast bed gasifier includes a fast bed gasification zone, a fast bed steam reforming zone and a fast bed methanation zone from bottom to top; preferably, a steam inlet is arranged on the side wall of the fast bed steam reforming zone, and a syngas return port is arranged on the side wall of the fast bed methanation zone.

[0028] According to some embodiments of the present invention, the fine powder settling / stripping device includes a stripping section, a fine powder settling section and a cyclone separator of the fine powder settling / stripping device; a stripping gas inlet for receiving stripping gas is arranged at the lower part of the side wall of the fine powder settling / stripping device; a semicoke outlet is arranged at the lower part of the side wall of the fine powder settling / stripping device, which is connected to the fluidized bed pyrolysis furnace through a gasification inclined pipe; a syngas outlet is arranged at the top of the fine powder settling / stripping device, which is connected to the gas outlet of the cyclone separator of the fine powder settling / stripping device for discharging the separated syngas.

[0029] According to a preferred embodiment of the present invention, a fast bed cyclone separator is provided inside the fine powder settler / stripper, which is connected to the upper outlet of the fast bed gasifier.

[0030] According to some embodiments of the present invention, the device further includes a post-treatment system, which includes:

[0031] A first gas-solid fast separator, which is connected to the pyrolysis gas outlet of the fluidized bed pyrolysis furnace;

[0032] A gas-liquid separation device, which is connected to the first gas-solid fast separator;

[0033] A second gas-solid fast separator, which is connected to the syngas outlet of the fine powder settler / stripper;

[0034] A gas separation device, which is connected to the second gas-solid fast separator and the gas-liquid separation device.

[0035] According to a preferred embodiment of the present invention, the first gas-solid fast separator is provided with a pyrolysis gas inlet, a first gas-solid fast separator gas outlet and a fly ash outlet. The pyrolysis gas inlet is connected to the pyrolysis gas outlet of the fluidized bed pyrolysis furnace, and the gas outlet is connected to the gas-liquid separation device.

[0036] According to a preferred embodiment of the present invention, the gas-liquid separation device is provided with a gas-liquid separation device gas inlet, a tar outlet and a gas-liquid separation device gas outlet. The gas-liquid separation device gas inlet is connected to the gas outlet of the first gas-solid fast separator, and the gas-liquid separation device gas outlet is connected to the gas separation device.

[0037] According to a preferred embodiment of the present invention, the second gas-solid fast separator is provided with a syngas inlet, a fly ash outlet and a second gas-solid fast separator gas outlet. The syngas inlet is connected to the syngas outlet of the fine powder settler / stripper, and the second gas-solid fast separator gas outlet is connected to the gas separation device.

[0038] According to a preferred embodiment of the present invention, the gas separation device is provided with a gas inlet, a recycle gas outlet and a syngas outlet. The gas inlet is respectively connected to the gas-liquid separation device gas outlet and the second gas-solid fast separator gas outlet, and the recycle gas outlet is connected to the syngas return port of the fast bed methanation zone.

[0039] According to some embodiments of the present invention, the device further includes a catalyst system, which includes a catalyst recovery device and a catalyst loading device; the upstream of the catalyst recovery device is connected to the ash tank, and the downstream is connected to the catalyst loading device; the upstream of the catalyst loading device is connected to the catalyst recovery device, and the downstream is connected to the feeder.

[0040] According to a preferred embodiment of the present invention, the catalyst recovery device is provided with an inlet, a slag outlet and a catalyst outlet. The inlet is connected to the slag tank, and the catalyst outlet is connected to the catalyst loading device.

[0041] According to a preferred embodiment of the present invention, the catalyst loading device is provided with a first catalyst inlet, a second catalyst inlet, a carrier inlet and a catalyst outlet. The first catalyst inlet is connected to the catalyst outlet of the catalyst recovery device. The second catalyst inlet is used to supplement the catalyst, and the carrier inlet is used to add the carrier. The catalyst outlet is connected to the feeder.

[0042] According to a preferred embodiment of the present invention, a pyrolysis semicoke return valve is provided on the pyrolysis inclined pipe. It is a non-mechanical return valve, preferably a U valve, a J valve, an L valve or an M valve. Loosening gas is introduced into the pyrolysis semicoke valve, and the circulation amount of pyrolysis semicoke, or the bed density of the fluidized bed gasifier, or the material level of the fluidized bed pyrolysis furnace is controlled by adjusting the air volume of the loosening gas.

[0043] According to a preferred embodiment of the present invention, a gasification semicoke return valve is provided on the gasification inclined pipe. It is a non-mechanical return valve, preferably a U valve, a J valve, an L valve or an M valve. Loosening gas is introduced into the gasification semicoke return valve, and the circulation amount of gasification semicoke, or the material level of the fine powder sedimentation / stripper, or the temperature of the fluidized bed pyrolysis furnace is controlled by adjusting the air volume of the loosening gas.

[0044] According to another aspect of the present invention, a method for increasing methane production by catalytic gasification of pulverized coal in a circulating fluidized bed is provided. The method uses the above-mentioned device and includes the following steps:

[0045] (a) The pulverized coal raw material is fed into the fluidized bed pyrolysis furnace by a feeder, and is heated by mixing with high-temperature gasification semicoke in the fluidized bed pyrolysis furnace. The pulverized coal undergoes a pyrolysis reaction to generate pyrolysis semicoke and pyrolysis gas;

[0046] (b) The pyrolysis semicoke enters the fluidized bed gasifier through the pyrolysis inclined pipe, contacts with the gasifying agent, and undergoes a gasification reaction in the fluidized bed gasifier and the fast bed gasifier to generate syngas and carbon-containing gasification semicoke;

[0047] (c) The syngas enters the fine powder sedimentation / stripper to separate out high-temperature gasification semicoke, and the high-temperature gasification semicoke enters the fluidized bed pyrolysis furnace through the gasification inclined pipe;

[0048] (d) The carbon-containing gasification semicoke enters the fluidized bed combustor downward from the fluidized bed gasifier, undergoes a combustion reaction to produce slag and high-temperature gas; the high-temperature gas enters the fluidized bed gasifier upward as the gasifying agent.

[0049] According to some embodiments of the present invention, the pulverized coal raw material includes pulverized coal and at least one of a catalyst and biomass; preferably, the catalyst includes at least one of an alkali metal, an alkaline earth metal, and a transition metal.

[0050] According to a preferred embodiment of the present invention, the catalyst is loaded on the pulverized coal by means such as impregnation method, dry mixing method, or ion exchange method, and the loading amount of the catalyst accounts for 0.1-30% of the mass of the pulverized coal.

[0051] According to some embodiments of the present invention, the pulverized coal raw material is fed into the dense phase region of the fluidized bed pyrolysis furnace by a feeder, and is heated by mixing with high-temperature gasified semicoke in the dense phase region. The pulverized coal undergoes a pyrolysis reaction to generate pyrolytic semicoke and pyrolysis gas; the pyrolytic semicoke enters the fluidized bed gasifier through a pyrolysis inclined pipe; the pyrolysis gas entraining fine pulverized coal enters the dilute phase region upward and is subjected to gas-solid separation by a cyclone separator of the fluidized bed pyrolysis furnace. The solid (fine pulverized coal) returns to the dense phase region, and the gas leaves the fluidized bed pyrolysis furnace and enters a first gas-solid fast separator and a gas-liquid separation device in sequence. Fly ash is separated in the first gas-solid fast separator, and then tar is separated in the gas-liquid separation device, and then enters a gas separation device.

[0052] According to a preferred embodiment of the present invention, the pyrolysis pressure of the fluidized bed pyrolysis furnace is 0-6.5 MPa, and the pyrolysis temperature is 400-800 °C; and / or, the average density of the pulverized coal in the dense phase region of the fluidized bed pyrolysis furnace is 200-550 kg / m 3 , and the superficial gas velocity is 0.1-1.0 m / s.

[0053] According to a preferred embodiment of the present invention, pyrolysis fluidizing gas is introduced into the fluidized bed pyrolysis furnace through a pyrolysis fluidizing gas inlet at the bottom thereof; the pyrolysis fluidizing gas includes at least one of water vapor, CO2, CO, hydrogen, and an inert gas.

[0054] According to some embodiments of the present invention, the pyrolytic semicoke enters the lower part of the fluidized bed gasifier through a pyrolysis inclined pipe, contacts with a gasifying agent, and undergoes a gasification reaction in the fluidized bed gasifier and a fast bed gasifier to generate synthesis gas and carbon-containing gasified semicoke. While the gasification reaction occurs in the fast bed gasifier, water vapor is introduced into the fast bed water gas shift zone to carry out a water vapor reaction (CO + H2O = CO2 + H2) to adjust the H2 / CO ratio; recycled synthesis gas is introduced into the fast bed methanation zone to carry out a methanation reaction (CO + 3H2 = CH4 + H2O) to increase the methane yield in the product.

[0055] According to a preferred embodiment of the present invention, loose gas is introduced into the pyrolytic semicoke valve, and the circulation amount of the pyrolytic semicoke, or the bed density of the fluidized bed gasifier, or the material level of the fluidized bed pyrolysis furnace is controlled by adjusting the air volume of the loose gas.

[0056] According to a preferred embodiment of the present invention, the loose gas includes at least one of water vapor, CO2, CO, air, oxygen, and inert gas.

[0057] According to a preferred embodiment of the present invention, the gasifying agent is a high-temperature gas from the fluidized bed combustion chamber or a gasifying agent from the outside introduced through the gasifying agent inlet; the gasifying agent includes water vapor and / or CO2.

[0058] According to a preferred embodiment of the present invention, the gasification pressure of the fluidized bed gasifier is 0 - 6.5 MPa, the gasification temperature is 700 - 1200 °C, and the average density of pulverized coal is 200 - 450 kg / m 3 , and the average superficial velocity of the empty tower is 0.2 - 1.2 m / s.

[0059] According to a preferred embodiment of the present invention, the gasification pressure of the fast bed water gas shift zone is 0 - 6.5 MPa, and the gasification temperature is 700 - 1000 °C; and / or, the gasification pressure of the fast bed methanation zone is 0 - 6.5 MPa, and the gasification temperature is 700 - 900 °C; and / or, the average density of pulverized coal in the fast bed gasifier is 50 - 150 kg / m 3 , and the average superficial velocity is 1.0 - 3.0 m / s.

[0060] According to some embodiments of the present invention, the syngas coming out of the fast bed gasifier carries ungasified semicoke fine powder, and first enters the fast bed cyclone separator for preliminary gas-solid separation. The solid falls into the stripping section of the fine powder sedimentation / stripper, and the gas enters the sedimentation section of the fine powder sedimentation / stripper.

[0061] According to a preferred embodiment of the present invention, the gas coming out of the fast bed cyclone separator enters the sedimentation section of the fine powder sedimentation / stripper and the fine powder sedimentation / stripper cyclone separator to further separate the solid. The solid falls into the stripping section of the fine powder sedimentation / stripper, and the gas leaves the fine powder sedimentation / stripper and enters the second gas-solid fast separator to separate and remove fly ash, and then enters the gas separation device together with the gas from the gas-liquid separation device; the gas separation device separates methane from the syngas and divides it into recycle gas (lean methane gas) and rich methane syngas; a part of the gas coming out of the gas separation device is recycled back to the fast bed methanation zone, and the other part is discharged as rich methane syngas.

[0062] According to a preferred embodiment of the present invention, stripping gas is introduced into the stripping section of the fine powder sedimentation / stripper through the stripping gas inlet to strip the solid in the stripping section, remove the fly ash entrained in the solid, and obtain high-temperature gasified semicoke. The high-temperature gasified semicoke enters the fluidized bed pyrolyzer through the gasification inclined pipe.

[0063] According to a preferred embodiment of the present invention, the stripping gas includes at least one of steam, CO2, CO, and inert gas.

[0064] According to a preferred embodiment of the present invention, a loosening gas is introduced into the gasification semicoke return valve, and the circulation amount of the gasification semicoke, or the level of the fine powder settling / stripper, or the temperature of the fluidized bed pyrolysis furnace is controlled by adjusting the air volume of the loosening gas.

[0065] According to a preferred embodiment of the present invention, the loosening gas includes at least one of steam, CO2, CO, air, oxygen, and inert gas.

[0066] According to a preferred embodiment of the present invention, the pressure of the fine powder settling / stripper is 0 - 6.5 MPa, the temperature is 700 - 1200 °C, and the average density of the pulverized coal is 350 - 550 kg / m 3 , and the average superficial velocity of the empty tower is 0.1 - 0.5 m / s.

[0067] According to some embodiments of the present invention, the carbon-containing gasification semicoke enters the fluidized bed combustion chamber downward from the fluidized bed gasifier, contacts with the oxidant, undergoes a combustion reaction to produce ash and high-temperature gas; the high-temperature gas enters the fluidized bed gasifier upward as a gasifying agent and provides heat for the gasification reaction; the ash is discharged to the ash tank through the ash discharge port, then enters the catalyst recovery device, where the catalyst and ash are separated, the ash is discharged externally, and the recovered catalyst enters the catalyst loading device, is loaded onto the carrier and then transported to the feeder as a raw material.

[0068] According to a preferred embodiment of the present invention, the oxidant includes air and / or oxygen.

[0069] According to a preferred embodiment of the present invention, the carrier includes pulverized coal, coke, and other carbon-containing substances.

[0070] According to a preferred embodiment of the present invention, the catalyst and / or biomass can also be supplemented into the catalyst loading device through the second catalyst inlet.

[0071] According to a preferred embodiment of the present invention, the combustion pressure of the fluidized bed combustion chamber is 0 - 6.5 MPa, the combustion temperature is 800 - 1500 °C, and the average density of the pulverized coal is 300 - 450 kg / m 3 , and the average superficial velocity of the empty tower is 0.2 - 0.6 m / s.

[0072] The technical solution of the present invention pyrolyzes pulverized coal raw materials in a pyrolysis furnace to obtain pyrolysis gas (including coal tar) and gasification raw materials - pyrolysis semicoke. By obtaining gasification raw materials through pyrolysis, the applicable range of coal types is expanded. The gasification reaction of pyrolysis semicoke particles is carried out in a gasification furnace to produce syngas. And most of the ungasified high-temperature gasified semicoke particles serve as heat carriers and are recycled into the pyrolysis furnace as the heat source for pyrolysis, reducing energy consumption and also saving the cost of externally loaded heat carriers in traditional processes. A small part of the ungasified gasified semicoke particles enter the combustion chamber to react with oxygen to burn the semicoke into ash slag, improving the carbon conversion rate and the utilization rate of residual carbon. The heat generated by the combustion reaction is used to supply the heat consumption and heat loss in the gasification reaction and provides the necessary gasifying agent for the gasification reaction. The present invention specifically provides a fine powder settling / stripper, the purpose of which is to remove the fly ash entrained in the high-temperature gasified semicoke entering the pyrolysis furnace, thereby reducing the fly ash entrained in the pyrolysis gas, avoiding the blockage of related equipment by fly ash, and reducing the difficulty of liquid-solid separation.

[0073] The present invention couples the processes of pyrolysis and gasification, gasification and combustion, gasification and conversion, methanation, etc. It realizes the partition coupling of gasification, conversion, and methanation in one gasification furnace, effectively improving the methane yield of the single-pass reaction. The separated syngas is recycled back to the methanation zone of the gasification furnace for further methanation reaction, producing methane-rich syngas and by-product coal tar, realizing the separate and hierarchical utilization of low-rank coal. It can carry out direct gasification of pulverized coal or catalytic gasification of pulverized coal. The catalyst is recycled after separation and recovery, realizing the efficient, clean, and reasonable comprehensive utilization of coal.

[0074] Adopting the technical solution of the present invention, compared with the prior art, the carbon conversion rate at the gasification outlet in the reactor is increased to 98%, the methane content in the syngas is increased to 15%, and the tar production is increased by 10%. It has the characteristics of high carbon conversion rate, high methane production rate, increased tar production, and high utilization rate of pulverized coal, achieving good technical effects. Brief Description of the Drawings

[0075] Figure 1 It is a schematic diagram of the pulverized coal circulating fluidized bed catalytic gasification methane-increasing device of the present invention:

[0076] Figure 1Among them, 1 is a feeder; 2 is a fluidized bed pyrolysis furnace; 3 is the dense phase zone of the fluidized bed pyrolysis furnace; 4 is the dilute phase zone of the fluidized bed pyrolysis furnace; 5 is the cyclone separator of the fluidized bed pyrolysis furnace; 6 is the pyrolytic semicoke return valve; 7 is a fluidized bed combustion chamber; 8 is a fluidized bed gasifier; 9 is a fast bed gasifier; 10 is the fast bed gasification zone; 11 is the fast bed steam reforming zone; 12 is the fast bed methanation zone; 13 is a fine powder settler / stripper; 14 is the cyclone separator of the fast bed gasifier; 15 is a stripping section; 16 is a fine powder settling section; 17 is the cyclone separator of the fine powder settler / stripper; 18 is a gas distribution plate; 19 is the ash discharge port; 20 is an ash tank; 21 is the gasified semicoke return valve; 22 is a feed inclined pipe; 23 is a pyrolysis inclined pipe; 24 is a gasification inclined pipe; 25 is a first gas-solid fast separator; 26 is a gas-liquid separation device; 27 is a second gas-solid fast separator; 28 is a gas separation device; 29 is a catalyst recovery device; 30 is a catalyst loading device; A is pulverized coal raw material; B is pyrolysis fluidizing gas; C is an oxidant; D is a gasifying agent; E is steam; F is stripping gas; G, H, I, J are loosening gases; K is fly ash; L is tar; M is methane-rich syngas; N is ash; U is a carrier; V is a catalyst and / or biomass. Detailed implementation manners

[0077] The present invention will be further described below by way of examples, but not limited to these examples.

[0078] In the following examples, the evaluation and testing methods involved are as follows:

[0079] The carbon conversion rate is calculated based on the residual carbon in the ash, and the specific formula is:

[0080] CC = (1 - C ash / C raw ) × 100%, where CC is the carbon conversion rate, C ash is the carbon content in the ash, and C raw is the carbon content in the pulverized coal raw material;

[0081] The gas components are measured by the external standard method of an on-line gas chromatograph, and the methane content in the syngas is measured;

[0082] The tar yield is calculated by the mass balance of the gas-liquid-solid products, and the specific formula is:

[0083] Y tar = (M raw - M gas - M ash ) / M raw × 100%, where Y tar is the tar yield, M raw is the mass flow rate of the pulverized coal raw material, M gas is the mass flow rate of the product gas, M ashis the mass flow rate of ash residue.

[0084]

Example 1

[0085] The reaction process is as follows: The raw materials are fed into the dense phase zone (3) of the fluidized bed pyrolysis furnace (2) by a feeder (1), and are heated after being mixed with the high-temperature gasified semicoke / ash residue from the gasifier, and pyrolysis reaction occurs. The pyrolysis gas entraining fine pulverized coal enters the subsequent first gas-solid quick separator (25) to remove fly ash K after gas-solid separation, and then enters the gas-liquid separation device (26) to separate the tar L product, and then enters the gas separation device (28); while the fine pulverized coal returns to the dense phase zone (3), and the pyrolytic semicoke enters the fluidized bed gasifier (8) to contact with the gasifying agent D after controlling the circulation amount, and gasification reaction occurs in the fluidized bed gasifier (8) and the fast bed gasifier (9) to generate syngas. While the gasification reaction occurs in the fast bed gasifier (9), steam E is introduced into the fast bed steam reforming zone (11) to carry out the steam reforming reaction to adjust the H2 / CO ratio, and recycled syngas is introduced into the fast bed methanation zone (12) to carry out the methanation reaction to increase the methane yield in the product. The syngas entraining semicoke fines enters the upper settling section (16) of the fine powder settler / stripper (13) after separation, and the un-gasified gasified semicoke falls into the stripping section (15) at the lower part of the fine powder settler / stripper (13). The syngas coming out from the top of the fast bed gasifier cyclone separator (14) enters the subsequent second gas-solid quick separator (27) to remove fly ash K, and then is mixed with the gas from the gas-liquid separation device (26) and enters the gas separation device (28), and part of the syngas is recycled back to the fast bed methanation zone (12) as recycle gas to further carry out the methanation reaction to increase the methane yield. The stripping section (15) uses stripping gas F to strip the unreacted carbonaceous semicoke to reduce the fly ash entrained in the unreacted carbonaceous semicoke. The stripped carbonaceous semicoke and ash residue compounds enter the lower part of the dense phase zone (3) of the fluidized bed pyrolysis furnace (2) after controlling the circulation amount, and are mixed with the fresh pulverized coal raw materials to heat the newly incoming pulverized coal raw materials for pyrolysis; the carbonaceous gasified semicoke and ash residue fall from the bottom of the fluidized bed gasifier (8) into the fluidized bed combustor (7), contact and mix with the oxidant C, and carry out the combustion reaction to convert the carbonaceous semicoke into ash residue, which is discharged from the device regularly or continuously. The high-temperature gas generated by combustion enters the fluidized bed gasifier (8) upward as the gasifying agent and provides heat for the gasification medium; the ash residue containing the catalyst discharged from the ash residue tank (20) enters the catalyst recovery device (29) to recover the catalyst after heat exchange and then is discharged, and the recovered catalyst enters the catalyst loading device (30) for recycling.

[0086] Lignite is used as the raw material in the reaction process. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, and the pyrolysis temperature is 400 °C. The average density of the pulverized coal in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 200 kg / m 3, the superficial gas velocity in the dense phase zone (3) of the fluidized bed pyrolysis furnace (2) reactor is 1.0 m / s; the gasification pressure of the fluidized bed gasifier (8) is 0, the gasification temperature is 700 °C, and the average density of pulverized coal is 200 kg / m 3 , the average superficial gas velocity in the fluidized bed gasifier (8) is 1.2 m / s; the gasification pressure of the fast bed gasification zone (10) is 0, the gasification temperature is 700 °C; the gasification pressure of the fast bed water vapor shift zone (11) is 0, the gasification temperature is 700 °C; the gasification pressure of the fast bed methanation zone (12) is 0, the gasification temperature is 700 °C; the average density of pulverized coal in the fast bed gasifier (9) is 50 kg / m 3 , the average superficial gas velocity is 3.0 m / s; the combustion pressure of the fluidized bed combustor (7) is 0, the combustion temperature is 800 °C, and the average density of pulverized coal is 300 kg / m 3 , the average superficial gas velocity in the fluidized bed combustor (7) is 0.6 m / s; the pressure of the fine powder settler / stripper (9) is 0, the temperature is 700 °C, and the average density of pulverized coal is 350 kg / m 3 , the average superficial gas velocity in the fine powder settler / stripper (9) is 0.5 m / s. Among them, the pyrolysis fluidized gas B adopts an inert atmosphere, and the gasifying agent D adopts water vapor. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 93%, the methane content in the syngas is increased to 12.8%, and the tar yield is 8.1%. The detailed results are shown in Table 1.

[0087]

Example 2

[0088] The reaction process is the same as that of Example 1. Lignite is used as the raw material in the reaction process. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 6.5 MPa, the pyrolysis temperature is 400 °C, and the average density of pulverized coal in the dense phase zone (3) of the fluidized bed pyrolysis furnace (2) reactor is 200 kg / m 3 , the superficial gas velocity in the dense phase zone (3) of the fluidized bed pyrolysis furnace (2) reactor is 1.0 m / s; the gasification pressure of the fluidized bed gasifier (8) is 0, the gasification temperature is 700 °C, and the average density of pulverized coal is 200 kg / m 3 , the average superficial gas velocity in the fluidized bed gasifier (8) is 1.2 m / s; the gasification pressure of the fast bed gasification zone (10) is 0, the gasification temperature is 700 °C; the gasification pressure of the fast bed water vapor shift zone (11) is 0, the gasification temperature is 700 °C; the gasification pressure of the fast bed methanation zone (12) is 0, the gasification temperature is 700 °C; the average density of pulverized coal in the fast bed gasifier (9) is 50 kg / m 3 , the average superficial gas velocity is 3.0 m / s; the combustion pressure of the fluidized bed combustor (7) is 0, the combustion temperature is 800 °C, and the average density of pulverized coal is 300 kg / m 3 , the average superficial gas velocity in the fluidized bed combustor (7) is 0.6 m / s; the pressure of the fine powder settler / stripper (9) is 0, the temperature is 700 °C, and the average density of pulverized coal is 350 kg / m 3, the average superficial velocity in the fine powder settling / stripper (9) is 0.5 m / s. Among them, the pyrolysis fluidizing gas B adopts an inert atmosphere, and the gasifying agent D adopts steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 93%, the methane content in the syngas is increased to 13.2%, and the tar yield is 7.7%. The detailed results are shown in Table 1.

[0089]

Example 3

[0090] The reaction process is the same as that in Example 1. Lignite is used as the raw material in the reaction process. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, and the pyrolysis temperature is 800 °C. The average density of pulverized coal in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 200 kg / m 3 , and the superficial velocity in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 1.0 m / s; the gasification pressure of the fluidized bed gasifier (8) is 0, the gasification temperature is 1200 °C, and the average density of pulverized coal is 200 kg / m 3 , and the average superficial velocity in the fluidized bed gasifier (8) is 1.2 m / s; the gasification pressure of the fast bed gasification zone (10) is 0, the gasification temperature is 1200 °C; the gasification pressure of the fast bed steam reforming zone (11) is 0, the gasification temperature is 1000 °C; the gasification pressure of the fast bed methanation zone (12) is 0, the gasification temperature is 900 °C; the average density of pulverized coal in the fast bed gasifier (9) is 50 kg / m 3 , and the average superficial velocity is 3.0 m / s; the combustion pressure of the fluidized bed combustor (7) is 0, the combustion temperature is 1500 °C, and the average density of pulverized coal is 300 kg / m 3 , and the average superficial velocity in the fluidized bed combustor (7) is 0.6 m / s; the pressure of the fine powder settling / stripper (9) is 0, the temperature is 1200 °C, and the average density of pulverized coal is 350 kg / m 3 , and the average superficial velocity in the fine powder settling / stripper (9) is 0.5 m / s. Among them, the pyrolysis fluidizing gas B adopts an inert atmosphere, and the gasifying agent D adopts steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 96%, the methane content in the syngas is increased to 16.3%, and the tar yield is 5.6%. The detailed results are shown in Table 1.

[0091]

Example 4

[0092] The reaction process is the same as that in Example 1. Lignite is used as the raw material in the reaction process. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, and the pyrolysis temperature is 800 °C. The average density of pulverized coal in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 200 kg / m 3 , and the superficial velocity in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 1.0 m / s; the gasification pressure of the fluidized bed gasifier (8) is 6.5 MPa, the gasification temperature is 1200 °C, and the average density of pulverized coal is 200 kg / m 3, the average superficial velocity in the fluidized bed gasifier (8) is 1.2 m / s; the gasification pressure in the fast bed gasification zone (10) is 6.5 MPa and the gasification temperature is 1200 °C; the gasification pressure in the fast bed water gas shift zone (11) is 6.5 MPa and the gasification temperature is 1000 °C; the gasification pressure in the fast bed methanation zone (12) is 6.5 MPa and the gasification temperature is 900 °C; the average density of pulverized coal in the fast bed gasifier (9) is 50 kg / m 3 , the average superficial velocity is 3.0 m / s; the combustion pressure in the fluidized bed combustor (7) is 6.5 MPa and the combustion temperature is 1500 °C, and the average density of pulverized coal is 300 kg / m 3 , the average superficial velocity in the fluidized bed combustor (7) is 0.6 m / s; the pressure in the fine powder settling / stripper (9) is 6.5 MPa and the temperature is 1200 °C, and the average density of pulverized coal is 350 kg / m 3 , the average superficial velocity in the fine powder settling / stripper (9) is 0.5 m / s. Among them, the pyrolysis fluidized gas B adopts an inert atmosphere, and the gasifying agent D adopts steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 96%, the methane content in the syngas is increased to 17.6%, and the tar yield is 5.2%. The detailed results are shown in Table 1.

[0093]

Example 5

[0094] The reaction process is the same as that in Example 1. Lignite is used as the raw material in the reaction process. The pyrolysis pressure in the fluidized bed pyrolyzer (2) is 0 and the pyrolysis temperature is 800 °C. The average density of pulverized coal in the dense phase zone (3) of the reactor of the fluidized bed pyrolyzer (2) is 550 kg / m 3 , the superficial velocity in the dense phase zone (3) of the reactor of the fluidized bed pyrolyzer (2) is 0.1 m / s; the gasification pressure in the fluidized bed gasifier (8) is 6.5 MPa and the gasification temperature is 1200 °C, and the average density of pulverized coal is 450 kg / m 3 , the average superficial velocity in the fluidized bed gasifier (8) is 0.2 m / s; the gasification pressure in the fast bed gasification zone (10) is 6.5 MPa and the gasification temperature is 1200 °C; the gasification pressure in the fast bed water gas shift zone (11) is 6.5 MPa and the gasification temperature is 1000 °C; the gasification pressure in the fast bed methanation zone (12) is 6.5 MPa and the gasification temperature is 900 °C; the average density of pulverized coal in the fast bed gasifier (9) is 150 kg / m 3 , the average superficial velocity is 1.0 m / s; the combustion pressure in the fluidized bed combustor (7) is 6.5 MPa and the combustion temperature is 1500 °C, and the average density of pulverized coal is 500 kg / m 3 , the average superficial velocity in the fluidized bed combustor (7) is 0.2 m / s; the pressure in the fine powder settling / stripper (9) is 6.5 MPa and the temperature is 1200 °C, and the average density of pulverized coal is 550 kg / m 3, the average superficial velocity in the fine powder sedimentation / stripper (9) is 0.1 m / s. Among them, the pyrolysis fluidizing gas B adopts an inert atmosphere, and the gasifying agent D adopts steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 96%, the methane content in the syngas is increased to 18.0%, and the tar yield is 5.1%. The detailed results are shown in Table 1.

[0095]

Example 6

[0096] The reaction process is the same as that of Example 1. Lignite is used as the raw material in the reaction process. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, and the pyrolysis temperature is 600 °C. The average density of pulverized coal in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 550 kg / m 3 , the superficial velocity in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 0.1 m / s; the gasification pressure of the fluidized bed gasifier (8) is 6.5 MPa, the gasification temperature is 900 °C, and the average density of pulverized coal is 450 kg / m 3 , the average superficial velocity in the fluidized bed gasifier (8) is 0.2 m / s; the gasification pressure of the fast bed gasification zone (10) is 6.5 MPa, and the gasification temperature is 900 °C; the gasification pressure of the fast bed water gas shift zone (11) is 6.5 MPa, and the gasification temperature is 850 °C; the gasification pressure of the fast bed methanation zone (12) is 6.5 MPa, and the gasification temperature is 800 °C; the average density of pulverized coal in the fluidized bed gasifier (9) is 150 kg / m 3 , the average superficial velocity is 1.0 m / s; the combustion pressure of the fluidized bed combustor (7) is 6.5 MPa, the combustion temperature is 1100 °C, and the average density of pulverized coal is 500 kg / m 3 , the average superficial velocity in the fluidized bed combustor (7) is 0.2 m / s; the pressure of the fine powder sedimentation / stripper (9) is 6.5 MPa, the temperature is 900 °C, and the average density of pulverized coal is 550 kg / m 3 , the average superficial velocity in the fine powder sedimentation / stripper (9) is 0.1 m / s. Among them, the pyrolysis fluidizing gas B adopts an inert atmosphere, and the gasifying agent D adopts steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 95%, the methane content in the syngas is increased to 18.5%, and the tar yield is 9.9%. The detailed results are shown in Table 1.

[0097]

Example 7

[0098] The reaction process is the same as that of Example 1. Lignite + 5% K2CO3 is used as the raw material in the reaction process. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, and the pyrolysis temperature is 600 °C. The average density of pulverized coal in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 550 kg / m 3, the superficial gas velocity in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 0.1 m / s; the gasification pressure of the fluidized bed gasifier (8) is 6.5 MPa, the gasification temperature is 900 °C, and the average density of pulverized coal is 450 kg / m 3 , the average superficial gas velocity in the fluidized bed gasifier (8) is 0.2 m / s; the gasification pressure of the fast bed gasification zone (10) is 6.5 MPa, the gasification temperature is 900 °C; the gasification pressure of the fast bed steam reforming zone (11) is 6.5 MPa, the gasification temperature is 850 °C; the gasification pressure of the fast bed methanation zone (12) is 6.5 MPa, the gasification temperature is 800 °C; the average density of pulverized coal in the fast bed gasifier (9) is 150 kg / m 3 , the average superficial gas velocity is 1.0 m / s; the combustion pressure of the fluidized bed combustor (7) is 6.5 MPa, the combustion temperature is 1100 °C, and the average density of pulverized coal is 500 kg / m 3 , the average superficial gas velocity in the fluidized bed combustor (7) is 0.2 m / s; the pressure of the fine powder settler / stripper (9) is 6.5 MPa, the temperature is 900 °C, and the average density of pulverized coal is 550 kg / m 3 , the average superficial gas velocity in the fine powder settler / stripper (9) is 0.1 m / s. Among them, the pyrolysis fluidized gas B adopts an inert atmosphere, and the gasifying agent D adopts steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 98%, the methane content in the syngas is increased to 19.8%, and the tar yield is 8.5%. The detailed results are shown in Table 1.

[0099]

Example 8

[0100] The reaction process is the same as that of Example 1. In the reaction process, the raw material used is lignite + 5% K2CO3. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, the pyrolysis temperature is 600 °C, and the average density of pulverized coal in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 550 kg / m 3 , the superficial gas velocity in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 0.1 m / s; the gasification pressure of the fluidized bed gasifier (8) is 6.5 MPa, the gasification temperature is 900 °C, and the average density of pulverized coal is 450 kg / m 3 , the average superficial gas velocity in the fluidized bed gasifier (8) is 0.2 m / s; the gasification pressure of the fast bed gasification zone (10) is 6.5 MPa, the gasification temperature is 900 °C; the gasification pressure of the fast bed steam reforming zone (11) is 6.5 MPa, the gasification temperature is 850 °C; the gasification pressure of the fast bed methanation zone (12) is 6.5 MPa, the gasification temperature is 800 °C; the average density of pulverized coal in the fast bed gasifier (9) is 150 kg / m 3 , the average superficial gas velocity is 1.0 m / s; the combustion pressure of the fluidized bed combustor (7) is 6.5 MPa, the combustion temperature is 1100 °C, and the average density of pulverized coal is 500 kg / m 3, the average superficial velocity in the fluidized bed combustion chamber (7) is 0.2 m / s; the pressure of the fine powder settling / stripper (9) is 6.5 MPa, the temperature is 900 °C, and the average density of the pulverized coal is 550 kg / m 3 , the average superficial velocity in the fine powder settling / stripper (9) is 0.1 m / s. Among them, the pyrolysis fluidizing gas B uses hydrogen, and the gasifying agent D uses steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 98%, the methane content in the syngas is increased to 20.2%, and the tar yield is 8.0%. The detailed results are shown in Table 1.

[0101]

Example 9

[0102] The reaction process is the same as that of Example 1. The raw materials in the reaction process are lignite + 5% K2CO3. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, the pyrolysis temperature is 600 °C, and the average density of the pulverized coal in the dense phase region (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 550 kg / m 3 , the superficial velocity in the dense phase region (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 0.1 m / s; the gasification pressure of the fluidized bed gasifier (8) is 6.5 MPa, the gasification temperature is 900 °C, and the average density of the pulverized coal is 450 kg / m 3 , the average superficial velocity in the fluidized bed gasifier (8) is 0.2 m / s; the gasification pressure of the fast bed gasification zone (10) is 6.5 MPa, the gasification temperature is 900 °C; the gasification pressure of the fast bed steam reforming zone (11) is 6.5 MPa, the gasification temperature is 850 °C; the gasification pressure of the fast bed methanation zone (12) is 6.5 MPa, the gasification temperature is 800 °C; the average density of the pulverized coal in the fast bed gasifier (9) is 150 kg / m 3 , the average superficial velocity is 1.0 m / s; the combustion pressure of the fluidized bed combustion chamber (7) is 6.5 MPa, the combustion temperature is 1100 °C, and the average density of the pulverized coal is 500 kg / m 3 , the average superficial velocity in the fluidized bed combustion chamber (7) is 0.2 m / s; the pressure of the fine powder settling / stripper (9) is 6.5 MPa, the temperature is 900 °C, and the average density of the pulverized coal is 550 kg / m 3 , the average superficial velocity in the fine powder settling / stripper (9) is 0.1 m / s. Among them, the pyrolysis fluidizing gas B uses an inert atmosphere, and the gasifying agent D uses CO2. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 98%, the methane content in the syngas is increased to 19.6%, and the tar production is increased by 8.5%. The detailed results are shown in Table 1.

[0103]

Comparative Example 1

[0104] The reaction process is the same as that of Example 1. The raw materials in the reaction process are lignite + 5% K2CO3. The pyrolysis pressure of the fluidized bed pyrolysis furnace (2) is 0, the pyrolysis temperature is 600 °C, and the average density of the pulverized coal in the dense phase region (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 550 kg / m3 , the superficial gas velocity in the dense phase zone (3) of the reactor of the fluidized bed pyrolysis furnace (2) is 0.1 m / s; the gasification pressure of the fluidized bed gasifier (8) is 6.5 MPa, the gasification temperature is 900 °C, and the average density of pulverized coal is 450 kg / m 3 , the average superficial gas velocity in the fluidized bed gasifier (8) is 0.2 m / s; the gasification pressure in the fast bed gasification zone (10) is 6.5 MPa, the gasification temperature is 900 °C; the gasification pressure in the fast bed steam reforming zone (11) is 6.5 MPa, the gasification temperature is 850 °C; the gasification pressure in the fast bed methanation zone (12) is 6.5 MPa, the gasification temperature is 800 °C; the average density of pulverized coal in the fast bed gasifier (9) is 150 kg / m 3 , the average superficial gas velocity is 1.0 m / s; the combustion pressure of the fluidized bed combustor (7) is 6.5 MPa, the combustion temperature is 1100 °C, and the average density of pulverized coal is 500 kg / m 3 , the average superficial gas velocity in the fluidized bed combustor (7) is 0.2 m / s; the fine powder settler / stripper (9) is not provided, and only the cyclone separator is used to replace the fine powder settler / stripper. The pyrolysis fluidized gas B uses an inert atmosphere; the gasifying agent D uses steam. Through the above scheme, the carbon conversion rate at the gasification outlet in the reactor is 90%, the methane content in the syngas is increased to 17.5%, and the tar yield is 7.8%. The detailed results are shown in Table 1.

[0105]

Comparative Example 2

[0106] The new Aoshan Group PDU gasification reaction device in the prior art is adopted (see Bi Jicheng, Development Progress of Catalytic Gasification (One-step) Coal to SNG Technology [C]. The Fourth Symposium on Technical Economy of Coal to SNG, 2013, Urumqi). The raw material uses lignite, and 10% potassium carbonate is added as a catalyst. The linear velocity is <10 m / s, the operating temperature is 800 °C, and the methane content in the outlet gas components obtained by gasification is 14%. However, its carbon conversion rate is 90%, and no tar product is generated. The results are shown in detail in Table 1.

[0107]

Comparative Example 3

[0108] The traditional Lurgi pressurized fixed bed gasification device in the prior art is adopted (see Wang Peng et al., Development and Application of Lurgi Coal Gasification Technology [J]. Clean Coal Technology, 2009, 15(5): 48-51). The raw material is lignite, the gasification temperature is 850 °C, the methane content in the outlet gas components is 8.3%, the tar yield is 9%, and the carbon conversion rate is only 90%. The results are shown in detail in Table 1.

[0109] Table 1

[0110]

[0111]

[0112]

[0113] For any numerical value mentioned in the present invention, if there is only a two-unit interval between any lowest value and any highest value, all values increasing by one unit each from the lowest value to the highest value are included. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is stated as 50 - 90, it means in this specification that the values 51 - 89, 52 - 88... as well as 69 - 71 and 70 - 71, etc. are specifically enumerated. For non-integer values, appropriate consideration can be given with 0.1, 0.01, 0.001 or 0.0001 as a unit. These are only some specifically indicated examples. In this application, in a similar manner, all possible combinations of the numerical values between the enumerated lowest value and highest value are considered to have been disclosed.

[0114] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. Modifications can be made to the present invention within the scope of the claims of the present invention as stipulated, and the present invention can be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A pulverized coal circulating fluidized bed catalytic gasification device for increasing methane production, comprising: A feeder; A fluidized bed pyrolysis furnace, which is connected to the feeder through a feed inclined pipe; A fluidized bed gasification furnace, which is connected to the fluidized bed pyrolysis furnace through a pyrolysis inclined pipe; A fast bed gasification furnace, the lower inlet of which is connected to the upper outlet of the fluidized bed gasification furnace; A fluidized bed combustion chamber, the upper inlet of which is connected to the lower outlet of the fluidized bed gasification furnace; A fine powder settling / stripping device, which is connected to the fluidized bed pyrolysis furnace through a gasification inclined pipe; The fast bed gasification furnace includes a fast bed gasification zone, a fast bed steam conversion zone and a fast bed methanation zone from bottom to top; a steam inlet is provided on the side wall of the fast bed steam conversion zone; The fluidized bed pyrolysis furnace includes a dense phase zone and a dilute phase zone; a pulverized coal inlet and a gasified semicoke inlet are respectively provided on the lower part of the side wall of the dense phase zone. The pulverized coal inlet is connected to the feeder through the feed inclined pipe; the gasified semicoke inlet is connected to the fine powder settling / stripping device through the gasification inclined pipe; a pyrolyzed semicoke outlet is provided on the side wall of the dense phase zone, which is connected to the fluidized bed gasification furnace through the pyrolysis inclined pipe; a fluidized bed pyrolysis furnace cyclone separator is provided in the dilute phase zone; A pyrolyzed semicoke inlet is provided at the lower part of the side wall of the fluidized bed gasification furnace, which is connected to the fluidized bed pyrolysis furnace through the pyrolysis inclined pipe; The fine powder settling / stripping device includes a stripping section, a fine powder settling section and a fine powder settling / stripping device cyclone separator; a stripping gas inlet is provided at the lower part of the side wall of the fine powder settling / stripping device for receiving stripping gas; a semicoke outlet is provided at the lower part of the side wall of the fine powder settling / stripping device, which is connected to the fluidized bed pyrolysis furnace through the gasification inclined pipe; a syngas outlet is provided at the top of the fine powder settling / stripping device, which is connected to the gas outlet of the fine powder settling / stripping device cyclone separator for discharging syngas.

2. The device according to claim 1, wherein A pyrolysis fluidizing gas inlet is provided at the bottom of the fluidized bed pyrolysis furnace for receiving pyrolysis fluidizing gas; and / or, a pyrolysis gas outlet is provided at the top of the fluidized bed pyrolysis furnace, which is connected to the gas outlet of the fluidized bed pyrolysis furnace cyclone separator for discharging pyrolysis gas.

3. The device according to claim 1 or 2, characterized in that, An ash discharge outlet is provided at the bottom of the fluidized bed combustion chamber, and the ash discharge outlet is connected to an ash tank.

4. The device according to claim 3, characterized in that A syngas return port is provided on the side wall of the fast bed methanation zone; and / or, a gasifying agent inlet is provided at the lower part of the side wall of the fluidized bed gasification furnace, and the gasifying agent inlet is used for receiving a gasifying agent.

5. The device according to claim 1 or 2, characterized in that, A fast bed cyclone separator is provided inside the fine powder settling / stripping device, which is connected to the upper outlet of the fast bed gasification furnace.

6. The device according to claim 1 or 2, characterized in that, The device further includes a post-treatment system, which includes: A first gas-solid fast separator, which is connected to the pyrolysis gas outlet of the fluidized bed pyrolysis furnace; A gas-liquid separation device, which is connected to the first gas-solid fast separator; A second gas-solid fast separator, which is connected to the syngas outlet of the fine powder settling / stripping device; A gas separation device, which is connected to the second gas-solid fast separator and the gas-liquid separation device.

7. The device according to claim 1 or 2, characterized in that, The device further includes a catalyst system, which includes a catalyst recovery device and a catalyst loading device; the upstream of the catalyst recovery device is connected to the ash tank, and the downstream is connected to the catalyst loading device; the upstream of the catalyst loading device is connected to the catalyst recovery device, and the downstream is connected to the feeder.

8. A method for catalytic gasification of pulverized coal in a circulating fluidized bed to increase methane production, which uses the device according to any one of claims 1-7, and includes the following steps: (a) The pulverized coal raw material is fed into the fluidized bed pyrolysis furnace by the feeder, and is heated by mixing with high-temperature gasified semicoke in the fluidized bed pyrolysis furnace. The pulverized coal undergoes a pyrolysis reaction to generate pyrolytic semicoke and pyrolysis gas; (b) The pyrolytic semicoke enters the fluidized bed gasification furnace through the pyrolysis inclined pipe, contacts the gasifying agent, and undergoes a gasification reaction in the fluidized bed gasification furnace and the fast bed gasification furnace to generate syngas and carbon-containing gasified semicoke; while the gasification reaction occurs in the fast bed gasification furnace, steam is introduced into the fast bed steam reforming zone to undergo a steam reaction; (c) The syngas enters the fine powder settling / stripping device to separate out the high-temperature gasified semicoke, and the high-temperature gasified semicoke enters the fluidized bed pyrolysis furnace through the gasification inclined pipe; (d) The carbon-containing gasified semicoke descends from the fluidized bed gasification furnace into the fluidized bed combustion chamber to undergo a combustion reaction, producing ash and high-temperature gas; the high-temperature gas ascends into the fluidized bed gasification furnace as the gasifying agent.

9. The method according to claim 8, wherein The pulverized coal raw material includes pulverized coal and at least one of a catalyst and biomass.

10. The method according to claim 9, wherein The catalyst includes at least one of an alkali metal, an alkaline earth metal, and a transition metal.

11. The method according to any one of claims 8-10, characterized in that, The pulverized coal raw material is fed into the dense phase zone of the fluidized bed pyrolysis furnace by the feeder, and is heated by mixing with high-temperature gasified semicoke in the dense phase zone. The pulverized coal undergoes a pyrolysis reaction to generate pyrolytic semicoke and pyrolysis gas; the pyrolytic semicoke enters the fluidized bed gasification furnace through the pyrolysis inclined pipe; the pyrolysis gas entrains fine pulverized coal and ascends into the dilute phase zone to be separated by the fluidized bed pyrolysis furnace cyclone separator. The solid returns to the dense phase zone, and the gas leaves the fluidized bed pyrolysis furnace and enters the first gas-solid fast separator and the gas-liquid separation device in sequence to remove fly ash and tar, and then enters the gas separation device.

12. The method according to any one of claims 8-10, characterized in that, The pyrolysis pressure of the fluidized bed pyrolysis furnace is 0 - 6.5 MPa, and the pyrolysis temperature is 400 - 800 °C; and / or, the average density of pulverized coal in the dense phase region of the fluidized bed pyrolysis furnace is 200 - 550 kg / m 3 , and the superficial gas velocity is 0.1 - 1.0 m / s.

13. The method according to any one of claims 8-10, characterized in that The pyrolytic semicoke enters the fluidized bed gasification furnace, contacts the gasifying agent, and undergoes a gasification reaction in the fluidized bed gasification furnace and the fast bed gasification furnace to generate syngas and carbon-containing gasified semicoke; while the gasification reaction occurs in the fast bed gasification furnace, recycled syngas is introduced into the fast bed methanation zone to undergo a methanation reaction.

14. The method according to any one of claims 8-10, characterized in that, The gasification pressure of the fluidized bed gasifier is 0 - 6.5 MPa, the gasification temperature is 700 - 1200 °C, and the average density of pulverized coal is 200 - 450 kg / m 3 , and the average superficial velocity is 0.2 - 1.2 m / s; and / or, the gasification pressure of the fast bed water vapor conversion zone is 0 - 6.5 MPa, and the gasification temperature is 700 - 1000 °C; and / or, the gasification pressure of the fast bed methanation zone is 0 - 6.5 MPa, and the gasification temperature is 700 - 900 °C; and / or, the average density of pulverized coal in the fast bed gasifier is 50 - 150 kg / m 3 , and the average superficial velocity is 1.0 - 3.0 m / s.

15. The method according to any one of claims 8 - 10, characterized in that The syngas coming out of the fast bed gasification furnace entrains ungasified semicoke fines. First, it enters the fast bed cyclone separator for gas-solid separation. The solid falls into the stripping section of the fine powder settling / stripping device, and the gas enters the settling section of the fine powder settling / stripping device; and / or, the gas coming out of the fast bed cyclone separator enters the settling section of the fine powder settling / stripping device and the fine powder settling / stripping device cyclone separator to further separate out the solid. The solid falls into the stripping section of the fine powder settling / stripping device, and the gas leaves the fine powder settling / stripping device and enters the second gas-solid fast separator to remove fly ash, and then enters the gas separation device; a part of the gas coming out of the gas separation device is recycled back to the fast bed methanation zone.

16. The method according to any one of claims 8-10, characterized in that, Stripping gas is introduced into the stripping section of the fine powder settler / stripper to strip the solids in the stripping section, obtaining high-temperature gasified semicoke, and the high-temperature gasified semicoke enters the fluidized bed pyrolysis furnace through the gasification inclined pipe.

17. The method according to any one of claims 8-10, characterized in that, The carbon-containing gasified semicoke enters the fluidized bed combustion chamber downward from the fluidized bed gasifier, contacts with the oxidant, undergoes a combustion reaction, producing ash and high-temperature gas; the high-temperature gas enters the fluidized bed gasifier upward as a gasifying agent; the ash is discharged externally.

18. The method according to any one of claims 8-10, characterized in that The pressure of the fine powder settler / stripper is 0 - 6.5 MPa, the temperature is 700 - 1200 °C, and the average density of pulverized coal is 350 - 550 kg / m 3 , and the average superficial velocity is 0.1 - 0.5 m / s; and / or, the combustion pressure of the fluidized bed combustor is 0 - 6.5 MPa, the combustion temperature is 800 - 1500 °C, and the average density of pulverized coal is 300 - 450 kg / m 3 , and the average superficial velocity is 0.2 - 0.6 m / s.

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