CN103756731B - A kind of reciprocating cycle double fluidized bed solid fuel gasification device and method - Google Patents

Abstract

The present invention is an alternating circulation double fluidized bed solid fuel gasification device and method. The solid fuel and the gas used for fluidization and reaction undergo pyrolysis and gasification reaction in the fluidized bed gasification reactor to generate combustible gas and gas. Solid coke and semi-coke that have not completely undergone pyrolysis and gasification reactions; the heat required for the pyrolysis reaction comes from high-temperature heat-carrying circulating bed materials; solid coke/semi-coke and heat-carrying circulating bed materials after releasing heat are based on the operation The state enters the pneumatic return device through the cyclone separator or overflow device, and then is sent to the combustion reactor in a controlled manner; the solid coke/semi-coke is burned in the combustion reactor to reheat the heat-carrying circulating bed material; after heating The heat-carrying circulating bed material enters the gasification reactor again through the feeding device to provide heat for the pyrolysis gasification reaction. The gasification device adapts to the operating parameters of bubbling fluidization and rapid fluidization at the same time, so as to achieve good adaptability to various combustible solids and high operating efficiency of the overall device.

Description

An alternating circulation double fluidized bed solid fuel gasification device and method

technical field

The invention relates to an alternating circulation double fluidized bed solid fuel gasification device, which belongs to the technical field of solid fuel energy. The alternating circulation double fluidized bed solid fuel gasification device is suitable for various aspects such as coal gasification and biomass gasification.

Background technique

With the rapid progress of today's society, the energy and environmental problems accompanying the development process have become increasingly prominent, which has created a realistic and urgent demand for the improvement of energy production and consumption methods and the development and utilization of new energy technologies.

As far as my country’s national conditions are concerned, the reserves of oil and natural gas are relatively small, especially the gap between oil demand and domestic production is large, and a large amount of oil needs to be imported from overseas oil-producing countries. At present, my country’s dependence on foreign oil has reached 60%. For Ensuring national energy security and maintaining people's stable life is an important hidden danger. Compared with the shortage of oil and natural gas resources, my country has abundant reserves of coal resources and huge output. Currently, coal accounts for about 70% of my country's total energy consumption. On the other hand, the output of combustible solid waste including biomass is also very large in my country, especially as one of the clean and renewable energy resources, the application of such resources is very important to make up for the gap in energy demand and improve the composition of energy consumption. Structure plays an important role, and it also has important practical significance for the realization of sustainable development and the improvement of ecological environment.

Solid fuel gasification is one of the basic technologies for the future energy, fuel and chemical raw material industries, and it is also one of the effective technologies for the current solid fuel utilization. Through gasification technology, coal, biomass and various solid wastes are converted into product gas or syngas. After the product gas is processed, it can be directly used as fuel, or it can be used as a substitute for natural gas to produce synthetic natural gas through further refining and methanation. Synthesis gas can be widely used in various chemical production as raw material gas for chemical synthesis process. Through synthesis, a variety of basic chemical raw materials and various fuel oils that can be used to replace petroleum products can be produced.

The research and development of gasification technology has a history of more than a century, and many different technologies have been formed in the process of its development. Current gasification technologies mainly include fixed bed/moving bed technology, fluidized bed technology, and entrained bed technology. Among them, fluidized bed gasification technology has the advantages of moderate working temperature and strong production capacity, but still has the disadvantage of fixing carbon. There are disadvantages such as high raw material requirements, low gasification conversion efficiency, difficult control, large tar output and low calorific value of gas production.

Dual fluidized bed gasification technology is a special fluidized bed gasification technology that has gradually attracted people's attention in recent years. The decoupling control of the complex chemical reaction network in the gasification of combustible solid materials is realized by using the special structure of the double fluidized bed. , so as to efficiently utilize the energy and substances produced in the gasification process. The dual fluidized bed devices currently designed for gasification technology mainly include three types: bubbling bed coupled with bubbling bed, bubbling bed coupled with circulating bed, and circulating bed coupled with circulating bed. The type of coupled gasification bed used in the design is limited. The raw material and working parameters of the dual fluidized bed gasification device, this type of device has relatively poor ability to respond to changes in material composition and size, and cannot fully adapt to the actual application of a variety of combustible solid raw materials.

Contents of the invention

Technical problem: One of the objectives of the present invention is to provide an alternating circulation double fluidized bed solid fuel gasification device. The device has a double fluidized bed alternating circulation loop, including a fluidized bed gasifier, a gasifier cyclone separator, a gasifier pneumatic return device, a fluidized bed combustion furnace, a combustion furnace cyclone separator, and a combustion furnace pneumatic return device. material device. The inlet pipe sections of the two return devices are respectively connected with the solid outlet of the cyclone separator and the overflow pipe of the reactor. The feeding device is used to send the solid material produced by one reactor to another reactor in a controlled manner so as to realize the interactive circulation and coupling between the double fluidized bed reactors.

Another object of the present invention is to provide an alternating circulation double fluidized bed solid fuel gasification method. The solid fuel is pyrolyzed and gasified in the gasification reactor to produce combustible gas. The coke/semi-coke produced by the reaction is sent to the combustion reactor through the feeding device, and is burned to release heat when mixed with heat carrier particles. The heated heat carrier returns to the gasification reactor through the circulation loop to provide the heat required for the gasification reaction. By using the design of alternating circulation double reactors to remove the coupling between the reactions involved in the gasification process, it is possible to differentiate and utilize the interactions between the reactions, thereby improving the utilization efficiency of energy and substances produced in the gasification process and Improve the quality of combustible gas.

Technical solution: In order to solve the above technical problems, the present invention provides an alternating circulation double fluidized bed solid fuel gasification device, the gasification device includes a fluidized bed gasification reactor and a fluidized bed combustion reactor;

The outlet of the upper part of the fluidized bed gasification reactor is connected with the cyclone separator of the gasification reactor, and then connected with the upper side of the gasification reactor feeder through the return downcomer; the middle part of the fluidized bed gasification reactor is provided with The overflow inclined pipe is connected with the return material drop pipe; the pneumatic return device of the gasification reactor is connected with the fluidized bed combustion reactor through the combustion reactor return inclined pipe;

The upper outlet of the fluidized bed combustion reactor is connected to the cyclone separator of the combustion reactor, and then connected to the upper side of the combustion reactor return material through the return downcomer; the middle part of the fluidized bed combustion reactor is provided with an overflow inclined pipe It is connected with the return material drop pipe; the pneumatic return device of the combustion reactor is connected with the fluidized bed gasification reactor through the gasification reactor return material inclined pipe.

Preferably, the superficial gas velocity of the fluidized bed gasification reactor is 0.4 to 5 m/s, and the superficial gas velocity of the fluidized bed combustion reactor is 0.4 to 5 m/s; the fluidized bed gasification reactor operates The operating temperature of the fluidized bed gasification reactor is 800-1000°C.

The present invention also provides a method for solid fuel gasification with alternating circulation double fluidized beds, the method comprises the following steps,

The solid fuel is fed into the fluidized bed gasification reactor through the inlet of the screw feeder, and the solid fuel is fluidized by the fluidizing gas supplied from the fluidizing gas inlet at the bottom of the fluidized bed reactor, and the fluidized The solid fuel is mixed with the high-temperature heat-carrying circulating bed material and heated up. The volatile matter in the solid fuel is first precipitated, and then the remaining solid fuel is pyrolyzed and gasified in the gasification reactor to produce combustible gas and coke/semi-coke. The combustible gas passes through The cyclone separator of the gasification reactor is separated and output, and the residual solid material including coke/semi-coke is mixed with the heat-carrying bed material and passes through the cyclone separator of the gasification reactor or the overflow inclined pipe of the gasification reactor according to different fluidization conditions It is sent to the pneumatic return device of the gasification reactor through the return downcomer, and then sent to the combustion reactor through the return inclined pipe of the combustion reactor; coke/semi-coke is used as fuel in the combustion reactor and is discharged from the bottom of the combustion reactor The fluidization gas fed into the fluidization gas inlet is fluidized, and the oxygen contained in the fluidization gas is used for combustion. The heat released by combustion is used to heat the heat-carrying circulating bed material, and the flue gas generated by combustion is passed through the cyclone separator of the combustion reactor. Separation and discharge; the heat-carrying circulating bed material after heating is sent to the combustion reactor’s pneumatic returner through the cyclone separator of the combustion reactor or the overflow inclined pipe of the gasification reactor according to the different fluidization conditions, and then sent to the pneumatic returner of the combustion reactor through the return material drop pipe, and then passed through the gasification reactor. The return inclined pipe of the gasification reactor enters the gasification reactor again, and releases heat to heat the solid fuel to make it pyrolyze and gasify, thus forming an alternate cycle between the double fluidized bed reactors.

Preferably, both the fluidized-bed gasification reactor and the fluidized-bed combustion reactor are in the bubbling flow state respectively through the valve switch provided on the overflow inclined pipe of the gasification reactor and the overflow inclined pipe of the combustion reactor. fluidized or rapidly fluidized operating state.

Beneficial effects: compared with the prior art, the present invention has the following characteristics and advantages:

(1) The present invention adopts an alternating circulation double fluidized bed operation method combining a fluidized bed gasification reactor and a fluidized bed combustion reactor, and utilizes a solid heat-carrying bed material to realize high-temperature gasification of solid fuel and coke/semi The organic combination of coke combustion, the endothermic pyrolysis gasification reaction and the exothermic combustion reaction are completed in the same device, realizing the joint output and separate utilization of energy and materials;

(2) The pyrolysis/gasification and combustion processes of the solid fuel in the method of the present invention are carried out in two fluidized beds respectively, which can be controlled separately and are easy to improve the operating efficiency of the overall system;

(3) The gasification device of the present invention adopts double fluidized bed reactors, which has the advantages of good adaptability to solid fuel types, low pollution emission, simple operation, and large processing capacity. On this basis, through special design, the device can adapt to the operation requirements of bubbling fluidization and rapid fluidization, so that the gasification device can deal with complex solid fuels including coal, biomass, etc., and Through the adjustment of operating parameters, the efficiency of combustion and gasification can be improved to the maximum extent, so as to realize the efficient utilization of materials and energy;

(4) The present invention can further adopt a multi-layer feeding structure and a multi-layer overflow structure, and adjust the feed and overflow positions according to the type of combustible solids and changes in operating parameters, so that different types of combustible solids can be placed in the device at the same time It is beneficial to the popularization and development of solid fuel gasification technology.

Description of drawings

Fig. 1 is a schematic diagram of the principle of an alternating circulation double fluidized bed gasification device of the present invention;

Fig. 2 is a schematic structural diagram of a gasification device for processing product gas and flue gas combined with a heat exchanger and a purification device for implementing the method of the present invention.

Among them: gasification reactor spiral feed inlet 1, gasification reactor fluidization gas inlet 2, fluidized bed gasification reactor 3, gasification reactor cyclone separator 4, gasification reactor overflow inclined pipe and Control valve 5, gasification reactor pneumatic return device 6, combustion reactor return inclined pipe 7, combustion reactor screw feed inlet 8, combustion reactor fluidization gas inlet 9, combustion reactor 10, combustion reactor cyclone Separator 11, combustion reactor overflow inclined pipe and control valve 12, combustion reactor pneumatic returner 13, gasification reactor return inclined pipe 14, gasification reactor pneumatic returner return gas inlet 15, combustion reactor Reactor Pneumatic Returner Return Gas Inlet 16, Gasification Reactor Outlet 17, Combustion Reactor Outlet 18, Combustible Gas Outlet 19, Flue Gas Outlet 20, Gasification Reactor Cyclone Separator Return Downcomer 21, Combustion Reactor The cyclone separator returns the downcomer 22, the combustible gas purification device A, the flue gas purification device B, the combustible gas heat exchanger C, and the flue gas heat exchanger D.

Detailed ways

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

Referring to Figures 1-2, the alternating circulation double fluidized bed solid fuel gasification device provided by the present invention includes a fluidized bed gasification reactor 3 and a fluidized bed combustion reactor 10; an upper outlet 17 of the fluidized bed gasification reactor It is connected with the cyclone separator 4 of the gasification reactor, and then connected with the upper side of the pneumatic return device 6 of the gasification reactor through the return downcomer 21 of the cyclone separator of the gasification reactor; the middle part of the fluidized bed gasification reactor The overflow inclined pipe of the gasification reactor and the control valve 5 are provided with the gasification reactor cyclone separator return material drop pipe 21; the pneumatic return device 6 of the gasification reactor passes through the combustion reactor return The bed combustion reactor is connected; the upper outlet 18 of the fluidized bed combustion reactor is connected with the combustion reactor cyclone separator 11, and then passes through the combustion reactor cyclone separator return material downcomer 22 and the combustion reactor pneumatic return feeder 13 tops The side phase connection; the middle part of the fluidized bed combustion reactor is provided with a combustion reactor overflow inclined pipe and a control valve 12 connected with the combustion reactor cyclone separator return material drop pipe 22; the combustion reactor pneumatic return device 13 passes through the gasification reaction The tank return inclined pipe 14 is connected with the fluidized bed gasification reactor.

The solid fuel is a mixture of lignite and biomass, which is fed into the fluidized bed gasification reactor 3 through the inlet 1 of the screw feeder, and the solid fuel is fed into the fluidized gas inlet 2 at the bottom of the fluidized bed reactor The fluidized gas is fluidized, the fluidized solid fuel is mixed with the high-temperature heat-carrying circulating bed material and heated up, the volatile matter in the solid fuel is first separated out, and then the remaining solid fuel is pyrolyzed and gasified in the gasification reactor 3, Combustible gas and solid coke/semi-coke are produced, the combustible gas is separated and output through the cyclone separator 4 of the gasification reactor, and the remaining solid materials including coke/semi-coke are mixed with heat-carrying bed materials and passed through gasification according to different fluidization conditions The cyclone separator 4 of the reactor or the overflow inclined pipe of the gasification reactor and the control valve 5 are sent to the pneumatic return device 6 of the gasification reactor through the return descending pipe, and then sent to the combustion reactor through the return inclined pipe 7 of the combustion reactor. Reactor 10. Coke/semi-coke is used as fuel in the combustion reactor 10 and is fluidized by the fluidization gas supplied from the fluidization gas inlet 9 at the bottom of the combustion reactor. By utilizing the oxygen contained in the fluidization gas for combustion, the heat released by combustion is used When heating the heat-carrying circulating bed material, the flue gas generated by combustion is separated and discharged by the cyclone separator 11 of the combustion reactor. The heat-carrying circulating bed material after heating is sent to the combustion reactor pneumatic returner 13 through the combustion reactor cyclone separator 11 or the combustion reactor overflow inclined pipe and the control valve 12 through the return material drop pipe according to different fluidization conditions, and then The gasification reactor returns to the inclined pipe 14 and re-enters the gasification reactor 3, and releases heat to heat the solid fuel to make it pyrolyze and gasify, thereby forming an alternate cycle between the double fluidized bed reactors.

The fluidized-bed gasification reactor 3 and the fluidized-bed combustion reactor 10 are both connected with the gasification reactor cyclone separator 4 and the combustion reactor cyclone separator 11 respectively with upper outlets provided, and both are in the fluidized-bed reactor The middle part is provided with the overflow inclined pipe of the gasification reactor and the control valve 5 which can be controlled and switched by the valve, the overflow inclined pipe of the combustion reactor and the control valve 12, the overflow inclined pipe of the gasification reactor and the control valve 5 and the gasification reactor After the cyclone separator return material drop pipe 21 is merged, it is connected to the pneumatic reactor 6 of the gasification reactor. Reactor pneumatic return device 13.

Both the fluidized bed gasification reactor 3 and the fluidized bed combustion reactor 10 can be switched through the valves provided on the overflow inclined pipe of the gasification reactor and the control valve 5 and the overflow inclined pipe and the control valve 12 of the combustion reactor. Make them respectively in the operating state of bubbling fluidization or rapid fluidization.

The superficial gas velocity of the fluidized bed gasification reactor 3 is 0.4-5 m/s, and the superficial gas velocity of the fluidized bed combustion reactor 10 is 0.4-5 m/s; the fluidized bed gasification reactor 3 operates The operating temperature of the fluidized bed gasification reactor 10 is 800-1000° C. at 700-900° C.

When the temperature in the fluidized bed gasification reactor 3 is lower than the design requirement, solid fuel can be added to the fluidized bed combustion reactor 10 through the combustion reactor screw feed inlet 8 or the fluidized gas inlet 9 of the combustion reactor can flow into the fluidized bed gasification reactor. Combustible gas is mixed into the combustion gas to increase the combustion intensity in the combustion reactor 10 and increase the working temperature in the reactor.

The fuel solid uses a mixture of biomass and lignite as the raw material, and the gasification reactor overflow inclined pipe of the fluidized bed gasification reactor 3 and the valve set on the control valve 5 are opened to make it operate as a bubbling fluidized bed, and the gasification reaction The superficial gas velocity in the reactor is set to 0.35～0.45m/s, and the valve provided on the combustion reactor overflow inclined pipe and the control valve 12 of the combustion reactor 10 is closed to make it run as a fast fluidized bed, and the internal combustion reactor The superficial gas velocity is set at 3.5-4m/s.

The solid fuel is sent into the fluidized bed combustion reactor 10 through the combustion furnace screw feeder inlet 8, the combustion reactor screw feeding speed is set to 0.5m/s, is ignited by the ignition device arranged in the combustion reactor, and Control the temperature inside the combustion reactor to be 900±20°C. When the temperature in the gasification reactor rises gradually and reaches the design range, solid fuel is added through the inlet 1 of the screw feeder of the gasification reactor, and the temperature in the gasification reactor is controlled at 800±20°C.

After the solid fuel is fed into the gasification fluidized bed 10, it is fluidized by the mixed gas of air and water vapor from the bottom fluidization gas inlet, and the high-temperature heat-carrying circulating bed material heats the solid fuel to make it pyrolyze and gasify under this environment. After the solid fuel is pyrolyzed and gasified, part of the composition is converted into combustible gas, and the remaining part of biomass and coal is converted into coke. The high-temperature combustible gas is output from the outlet 19 of the cyclone separator of the gasification reactor, first passes through the combustible gas heat exchanger C as the first-stage preheating and heating input air, and then passes through the combustible gas purification device A for further purification and separation of tar to obtain Combustible gas products, used as fuel or industrial raw materials. The coke and heat-exchanged bed material flows out from the overflow port through the overflow inclined pipe of the gasification reactor and the control valve 5 and enters the pneumatic return device 6 of the gasification reactor. The return device of the gasification reactor is equipped with a fluidization gas inlet 15. Here, the air is sent into the gasification reactor and the pneumatic return device 6 is used to send the coke generated by the reaction of biomass and coal and the bed material after heat exchange into the fluidized bed combustion reactor 10.

Air is fed in as fluidizing air from the fluidization gas inlet 9 of the combustion reactor at the bottom of the fluidized bed combustion reactor 10 , and auxiliary fuel is fed in from the screw feeder inlet 8 of the combustion reactor. The coke and auxiliary fuel remaining from the gasification of biomass and coal burn in the combustion reactor 10 and release heat to raise the temperature of the heat-carrying circulating bed material. The heated heat-carrying circulating bed material and high-temperature flue gas rise into the combustion reactor cyclone separator 11, where the high-temperature flue gas is separated and then output from the outlet 20 of the combustion reactor cyclone separator, which is used for the flue gas heat exchanger D pair The air is preheated in the second stage, and then the pollutants are treated by the flue gas purification device B and then discharged into the environment. The high-temperature heat-carrying circulating bed material is separated and enters the pneumatic reactor 13 of the combustion reactor through the return material drop pipe 22 of the cyclone separator of the combustion reactor, and then returns to the gasification reactor through the inclined return pipe 14 of the gasification reactor. . The high-temperature heat-carrying circulating material and solid fuel exchange heat through heat transfer methods such as heat convection, while the high-temperature bed material plays a catalytic role.

The feeders are interconnected double-chamber structures, including the feeding chamber and the discharging chamber, which can realize the controllable circulation of materials between the double-fluidized bed reactors and effectively prevent the channeling of gases in the gasification device. The air flow in the recirculator can control the flux of the recirculated material.

Claims (2)

1. A double fluidized bed solid fuel gasification device with alternating circulation, characterized in that, the gasification device comprises a fluidized bed gasification reactor (3) and a fluidized bed combustion reactor (10); The upper outlet (17) of the fluidized bed gasification reactor (3) is connected with the cyclone separator (4) of the gasification reactor, and then the gasification reactor cyclone separator returns the downcomer (21) to the gasification reactor. The upper part of the pneumatic return device (6) is connected to one side; the middle part of the fluidized bed gasification reactor is provided with a gasification reactor overflow inclined pipe and a control valve (5) and the gasification reactor cyclone separator return material drop pipe ( 21) are connected; the gasification reactor pneumatic return device (6) is connected to the fluidized bed combustion reactor (10) through the combustion reactor return inclined pipe (7); The outlet (18) on the upper part of the fluidized bed combustion reactor (10) is connected with the cyclone separator (11) of the combustion reactor, and then passes through the cyclone separator of the combustion reactor and returns the downcomer (22) to the pneumatic return device of the combustion reactor. (13) One side of the upper part is connected; the middle part of the fluidized bed combustion reactor is provided with a combustion reactor overflow inclined pipe and a control valve (12) connected with the combustion reactor cyclone separator return material drop pipe (22); the combustion reactor The pneumatic return device (13) is connected to the fluidized bed gasification reactor through the gasification reactor return inclined pipe (14); The superficial gas velocity of the fluidized bed gasification reactor (3) is 0.4 to 5 m/s, and the superficial gas velocity of the fluidized bed combustion reactor (10) is 0.4 to 5 m/s; the fluidized bed gasification The operating temperature of the reactor (3) is 700-900°C, and the operating temperature of the fluidized bed combustion reactor (10) is 800-1000°C. 2. A method for gasification of solid fuels in double fluidized beds with alternating circulation, characterized in that the method comprises the following steps, The solid fuel is added to the fluidized bed gasification reactor (3) through the screw feeder inlet (1), and the solid fuel is fed by the flow fed from the fluidized gas inlet (2) at the bottom of the fluidized bed reactor. The fluidized gas is fluidized, the fluidized solid fuel is mixed with the high-temperature heat-carrying circulating bed material and heated up, the volatile matter in the solid fuel is first precipitated, and then the remaining solid fuel is pyrolyzed and gasified in the gasification reactor (3). Combustible gas and coke/semi-coke are produced, the combustible gas is separated and output through the cyclone separator (4) of the gasification reactor, and the remaining solid materials including coke/semi-coke are mixed with the heat-carrying bed material and passed through the gas according to different fluidization conditions. The cyclone separator (4) of the gasification reactor or the overflow inclined pipe of the gasification reactor and the control valve (5) are sent to the pneumatic return device (6) of the gasification reactor through the return material drop pipe, and then the material is returned through the combustion reactor The inclined tube (7) is sent into the fluidized bed combustion reactor (10); coke/semi-coke is used as fuel in the fluidized bed combustion reactor (10) and is supplied by the fluidized gas inlet (9) at the bottom of the combustion reactor The incoming fluidization gas is fluidized, and the oxygen contained in the fluidization gas is used for combustion, and the heat released by combustion is used to heat the heat-carrying circulating bed material, and the flue gas generated by combustion is separated and discharged by the combustion reactor cyclone separator (11) ; The heat-carrying circulating bed material after heating is sent to the combustion reactor through the combustion reactor cyclone separator (11) or the overflow inclined pipe of the combustion reactor and the control valve (12) according to the different fluidization conditions, and is sent to the combustion reactor through the return material drop pipe. feeder (13), and then re-enter the gasification reactor (3) through the gasification reactor return inclined pipe (14), and release heat to heat the solid fuel to make it pyrolyze and gasify, thereby forming a double fluidized bed reaction The interactive loop between devices; Both the fluidized bed gasification reactor (3) and the fluidized bed combustion reactor (10) pass through the gasification reactor overflow inclined pipe and control valve (5) and the combustion reactor overflow inclined pipe and control valve (12 ) The valve switch set on it makes it respectively in the operating state of bubbling fluidization or rapid fluidization.