CN106025313A - Integrated coal gasification fuel cell power generation system capable of CO2 capture before combustion - Google Patents

Abstract

The invention provides an integrated gasification fuel cell power generation system capable of realizing CO2 trapping before combustion. The integrated gasification fuel cell (IGFC) power generation system comprises an air separation unit, a gasifier, a waste heat recovery device, a dust collection device, a water-gas shift device, a desulfurizing device, a CO2 purification device, a fuel humidifier, a separator, a compression and liquidation device, a catalytic burner, a first heat exchanger, a molten carbonate fuel cell, a compressor, a second heat exchanger, a third heat exchanger, a turbine, a power generator and a DC/AC converter. The integrated gasification fuel cell power generation system realizes CO2 trapping before combustion in an IGFC based on the molten carbonate fuel cell, so that CO2 emission of the system is reduced by 75% or above, the environment-friendly property of the IGFC system is greatly improved, and accordingly, clean and efficient utilization of coal resources can be realized.

Description

Integrated coal gasification fuel cell power generation system capable of CO2 capture before combustion

technical field

The invention belongs to the technical field of power generation, and in particular relates to an integrated coal gasification fuel cell power generation system capable of capturing _CO2 before combustion.

Background technique

The global environmental problems centered on climate change are becoming more and more serious, and have become one of the main factors threatening the sustainable development of human beings. Reducing greenhouse gas emissions to mitigate climate change has become a hot spot in the international community today. As the world pays more and more attention to greenhouse gas emissions, the "Kyoto Protocol" and "Bali Island Roadmap" have further clarified the global CO ₂ emission reduction goals and timetable, and promoted the development of the global low-carbon economy.

The integrated gasification fuel cell (Integrated Gasification Fuel Cell, IGFC) power generation system is a new generation of advanced coal-fired power generation technology that combines fuel cell power generation technology and coal gasification technology. Gas cleaning system and fuel cell power generation system. From the perspective of the development direction of large-scale and commercialization, IGFC organically combines the characteristics of high efficiency, cleanliness, waste utilization, polygeneration and water saving, and is considered to be the most promising clean coal power generation technology in the 21st century. It not only improves the power generation efficiency, but also proposes a way to solve environmental problems.

Fuel cell power generation technology is a power generation device that directly converts the chemical energy of fuel into electrical energy. Unlike traditional coal-fired power generation technology, fuel cells use electrochemical catalysis to directly convert the chemical energy in fuel into electrical energy. Because there is no thermodynamic The cycle thus surpasses the limit of the Carnot cycle efficiency of the heat engine. At present, the total efficiency of the fuel cell is between 45 and 60%. If the various generated heat is fully utilized, its comprehensive power generation efficiency can be close to 60%, far exceeding that of conventional coal-fired power stations ( 35%) and the power generation efficiency of advanced gas-steam combined cycle (about 45%), the application of fuel cell technology in the field of clean coal has been highly valued by industrially developed countries.

Molten Carbonate Fuel Cell (MCFC), a high-temperature battery in a fuel cell, requires CO ₂ and oxygen in the air as oxidants, and CO ₂ and oxygen are catalytically converted to CO ₃ ^2- at the MCFC cathode, CO ₃ ² - Reach the anode through the electrolyte layer and react with the H ₂ reformed and converted by the organic matter to generate CO ₂ and water. This process can use the CO ₂ in the flue gas of the coal-fired power plant to concentrate CO _{2 to achieve CO 2 enrichment} and capture the goal of. Therefore, the further realization of _CO2 capture on the basis of IGFC system is beneficial to promote the development of low-carbon economy.

Contents of the invention

The purpose of the present invention is to provide an integrated coal gasification fuel cell power generation system that can capture _CO2 before combustion. The present invention realizes _CO2 capture before combustion in the IGFC based on molten carbonate fuel cells, enabling the system The emission of CO ₂ is reduced by more than 75%, which greatly improves the environmental protection characteristics of the IGFC system, thereby enabling the clean and efficient utilization of coal resources.

In order to achieve the above object, the present invention adopts the following technical solutions:

An integrated coal gasification fuel cell power generation system capable of capturing _CO before combustion, comprising an air separation unit 1, the inlet of the air separation unit is fed with air, the oxygen outlet of the air separation unit 1 is connected to the oxygen inlet of the gasifier 2, and the air The nitrogen outlet of the sub-unit 1 is connected to the nitrogen storage device, the coal inlet of the gasifier 2 is fed with coal, the steam inlet of the gasifier 2 is fed with steam, the high-temperature gas outlet of the gasifier is connected with the waste heat recovery device 3, and the gas of the waste heat recovery device 3 The outlet is connected to the inlet of the dedusting device 4, the outlet of the dedusting device 4 is connected to the inlet of the water vapor shifting device 5, the outlet of the water vapor shifting device 5 is connected to the inlet of the desulfurization device 6, and the outlet of the desulfurizing device 6 is connected to the inlet of the _CO2 purification device 7, _CO2 The _H2 outlet of the purification device 7 is connected to the inlet of the fuel humidifier 8, and the _CO2 outlet of the _CO2 purification device 7 is connected to the inlet of the separator 9; the _CO2 gas at the first outlet of the separator 9 is passed into the compression liquefaction device 10 , the outlet of the compression liquefaction device 10 outputs liquid CO ₂ ; the CO ₂ gas from the second outlet of the separator 9 passes into the catalytic burner 11 ; the outlet of the fuel humidifier 8 is connected to the low-temperature gas inlet of the first heat exchanger 12 , the second The low-temperature gas outlet of a heat exchanger 12 is connected to the anode inlet of the molten carbonate fuel cell 13, and the anode outlet of the molten carbonate fuel cell 13 is connected to the second inlet of the catalytic burner 11; the inlet of the compressor 14 is fed into air, The outlet of the compressor 14 is connected to the low-temperature gas inlet of the second heat exchanger 15, the low-temperature gas outlet of the second heat exchanger 15 is connected to the low-temperature gas inlet of the third heat exchanger 16, and the low-temperature gas outlet of the third heat exchanger 16 is connected to The gas inlet of the turbine 17 and the gas outlet of the turbine 17 are connected to the third inlet of the catalytic burner 11. At the same time, the turbine 17 outputs shaft power to the outside, and the output shaft power drives the compressor 14 to rotate, and at the same time drives the generator 18 Rotate and output electric energy; the gas outlet of the catalytic burner 11 is connected to the high-temperature gas inlet of the third heat exchanger 16, and the high-temperature gas outlet of the third heat exchanger 16 is connected to the cathode inlet of the molten carbonate fuel cell 13, and the molten carbonate The cathode outlet of the fuel cell 13 is connected to the high-temperature gas inlet of the first heat exchanger 12, the high-temperature gas outlet of the first heat exchanger 12 is connected to the high-temperature gas inlet of the second heat exchanger 15, and the high-temperature gas outlet of the second heat exchanger 15 Exhaust gas; electrochemical reaction occurs in the molten carbonate fuel cell 13 to generate direct current, the direct current is input to the DC/AC converter 19, and the DC/AC converter 19 outputs alternating current.

The air separation unit 1 separates oxygen and nitrogen in the air through a cryogenic method, and the oxygen is transported to the gasifier 2 .

The reaction in the gasification furnace 2 produces synthesis gas, which mainly consists of H ₂ , H ₂ O, CO, CO ₂ , CH ₄ , H ₂ S and COS.

The waste heat recovery device 3 recovers the heat in the synthesis gas through the waste heat boiler, and produces steam.

The dust removal device 4 adopts a bag filter or an electric dust collector or a ceramic filter to remove particulate matter in the syngas so that the content of mineral dust is less than 100 mg/Nm ³ .

The water-vapor shift device 5 adopts a sulfur-resistant water-vapor shift process, and converts CO in the synthesis gas into _H2 through the water-vapor shift reaction CO+H ₂ O=H ₂ +CO ₂ , so that the proportion of CO in the outlet gas is lower than 0.5%. .

The desulfurization device 6 adopts a low-temperature methanol washing method or an NHD method, so that the H ₂ S and COS contents at the outlet are less than 1 ppm.

The CO ₂ purification device 7 adopts the pressure swing adsorption method to separate CO _{2 in the synthesis gas, the concentration of CO 2 is} higher than 99%, and the remaining gas is used as H ₂ fuel gas.

The fuel humidifier 8 adopts steam mixing method to increase the content of H ₂ O in the H ₂ fuel so that the molar content of H ₂ O is >5%.

The catalytic burner 11 makes H ₂ , CO and CH ₄ in the gas react with O ₂ through a catalyst to generate H ₂ O and release heat.

The molten carbonate fuel cell 13 is composed of an anode, a cathode, and an electrolyte diaphragm. The cathode and the anode are respectively on both sides of the electrolyte diaphragm. The fuel and the oxidant are passed into the anode and cathode chambers respectively, and an electrochemical reaction occurs to generate electrical energy. and heat, the operating temperature of the battery is 650°C, and the scale of the battery is amplified by connecting multiple battery stacks in series and parallel.

The compressor 14, turbine 17 and generator 18 are installed on the same shaft, and the turbine 17 rotates under the impact of high-pressure and high-temperature gas to drive the compressor 14 and generator 18 to rotate, and the compressor 14 makes the pressure of the air change from normal to normal. Pressure increases to more than 4Mpa, generator 18 then produces alternating current electric energy.

The present invention realizes _CO2 capture before combustion in the IGFC based on molten carbonate fuel cells, can reduce the _CO2 emission of the system by more than 75%, greatly improves the environmental protection characteristics of the IGFC system, and thus can realize coal resource clean and efficient use.

Description of drawings

Fig. 1 is a schematic diagram of an integrated coal gasification fuel cell power generation system capable of capturing CO ₂ before combustion according to the present invention.

detailed description

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

Implementation case

Coal, steam and oxygen are passed into the gasifier 2 to produce syngas. The temperature of the syngas is 900°C. The composition of the syngas is CO≈67%, H ₂ ≈25%, CO ₂ ≈7%, and the remaining components are N2 and H2S , COS, CH ₄ and other impurity gases. The synthesis gas first passes through the waste heat recovery device 3 for heat exchange, and the temperature drops below 150°C, and then passes into the dust removal device 4, so that the particle content is lower than 100mg/Nm ³ ; and then passes into the water vapor shift device 5, so that the CO in the synthesis gas <0.5%, H ₂ >60%; then pass into the desulfurization device 6, so that the concentration of H ₂ S and COS is lower than 1ppm; then pass into the CO ₂ purification device 7, and increase the concentration of CO ₂ to 99% by pressure swing adsorption % above, the rest of the gas is used as _H2 fuel gas. The high-concentration CO ₂ gas is divided into two streams through the separator 9 , 75% of the CO ₂ gas is passed into the compression liquefaction device 10 to become liquid CO ₂ , and the other 25% of the CO ₂ gas is passed into the catalytic burner 11 . The H ₂ fuel gas passes through the fuel humidifier 8, so that the H ₂ O molar content in the gas is >5%, and then passes through the first heat exchanger 12 so that the temperature of the H ₂ fuel gas rises to 500°C and then passes into the molten carbonate fuel cell The anode of the (MCFC) 13 undergoes an electrochemical reaction H ₂ +CO ₃ ²⁻ =H ₂ O+CO ₂ +e ²⁻ , and the gas at the anode outlet passes into the catalytic burner 11 . At the same time, the air is pressurized to 6Mpa through the compressor 14, and then the temperature of the air is raised to above 800°C through the second heat exchanger 15 and the third heat exchanger 16, and then the air passes through the turbine 17 to do work and drive the compressor 14 The rotation and the generator 18 generate electricity, and the air passes through the turbine 17 to reduce the temperature and pressure, and further passes into the catalytic burner 11 . In the catalytic burner 11, the unreacted _H2 in the anode outlet gas of the molten carbonate fuel cell (MCFC) 13 undergoes a chemical reaction to release heat, raise the gas temperature to above 900°C, and then pass through the third heat exchanger 16 to cool down Pass into the molten carbonate fuel cell (MCFC) 13 cathode chamber, the electrochemical reaction O ₂ +2CO ₂ +4e ^- =CO ₃ ^2- occurs at the cathode, the fuel and oxidant in the molten carbonate fuel cell (MCFC) Electrochemical reaction occurs in 13 to generate direct current, which is converted into alternating current through DC/AC converter 19 .

Claims (10)

1. one kind can realize the front CO that burns₂The integral coal gasification fuel cell generation of trapping, its feature Being: include air separation unit (1), air separation unit entrance is passed through air, and the oxygen of air separation unit (1) goes out Mouth connects the oxygen intake of gasification furnace (2), and the nitrogen outlet of air separation unit (1) connects nitrogen storage device, gas The coal entrance changing stove (2) adds coal, and the steam inlet of gasification furnace (2) adds steam, gasification furnace (2) High-temperature gas outlet connects waste-heat recovery device (3), and the gas outlet of waste-heat recovery device (3) connects dedusting The entrance of device (4), the outlet of dust arrester (4) connects the entrance of water-gas shift device (5), steam The outlet of converting means (5) connects the entrance of desulfurizer (6), and the outlet of desulfurizer (6) connects CO₂ The entrance of purifying plant (7), CO₂The H of purifying plant (7)₂Outlet connects entering of fuel humidifier (8) Mouthful, CO₂The CO of purifying plant (7)₂Outlet connects the entrance of separator (9)；The of separator (9) The CO of one outlet₂Gas is passed into and compresses and liquefies in device (10), compresses and liquefies the outlet of device (10) Output liquid CO₂；Second outlet CO of separator (9)₂Gas is passed in catalytic burner (11)； The outlet of fuel humidifier (8) connects the cryogenic gas entrance of First Heat Exchanger (12), First Heat Exchanger (12) Cryogenic gas outlet connect molten carbonate fuel cell (13) anode inlet, fused carbonate fuel The anode export of battery (13) connects the second entrance of catalytic burner (11)；Entering of compressor (14) Mouth is passed through air, and the outlet of compressor (14) connects the cryogenic gas entrance of the second heat exchanger (15), the The cryogenic gas entrance of cryogenic gas outlet connection the 3rd heat exchanger (16) of two heat exchangers (15), the 3rd The cryogenic gas outlet of heat exchanger (16) connects the gas access of turbine (17), the gas of turbine (17) Outlet connects the 3rd entrance of catalytic burner (11), and meanwhile, turbine (17) externally exports shaft work, The shaft work of output drives compressor (14) to rotate, and drives electromotor (18) rotate and export electric energy simultaneously； The gas outlet of catalytic burner (11) connects the high-temperature gas entrance of the 3rd heat exchanger (16), and the 3rd changes The high-temperature gas outlet of hot device (16) connects the cathode inlet of molten carbonate fuel cell (13), melted The cathode outlet of carbonate fuel battery (13) connects the high-temperature gas entrance of First Heat Exchanger (12), the The high-temperature gas entrance of high-temperature gas outlet connection the second heat exchanger (15) of one heat exchanger (12), second Waste gas is discharged in the high-temperature gas outlet of heat exchanger (15)；Electricity is there is in molten carbonate fuel cell (13) Chemical reaction produces unidirectional current, DC supply input to DC/AC transducer (19), DC/AC transducer (19) Externally output AC electricity.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described air separation unit (1) by Deep Cooling Method by the oxygen in air and Nitrogen separates, and oxygen is transported in gasification furnace (2)；In described gasification furnace (2), reaction generates and closes Becoming gas, it is H that synthesis gas mainly becomes₂、H₂O、CO、CO₂、CH₄、H₂S and COS.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described waste-heat recovery device (3) reclaims synthesis gas by waste heat boiler In heat, and producing steam.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described dust arrester (4) use sack cleaner or electric cleaner or Ceramic filter, the particulate matter in removing synthesis gas so that mine dust content is less than 100mg/Nm³。

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described water-gas shift device (5), use resistant to sulfur water-gas shift technique, By water gas shift reation CO+H₂O=H₂+CO₂CO in synthesis gas is transformed to H₂So that work off one's feeling vent one's spleen In body, CO ratio is less than 0.5%；Described desulfurizer (6) uses low-temp methanol to wash method or NHD method, makes Obtain exit H₂S and COS content is less than 1ppm.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described CO₂Purifying plant (7), uses pressure swing adsorption method, separates CO in synthesis gas₂, CO₂Concentration higher than 99%, residual gas is as H₂Fuel gas.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described fuel humidifier (8), use steam method, improve H₂ Fuel wherein H₂The content of O so that H₂The molar content of O > 5%.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described catalytic burner (11) is made in gas by catalyst H₂, CO and CH₄With O₂Chemical reaction is occurred to generate H₂O also discharges heat.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described molten carbonate fuel cell (13) by anode, negative electrode, Electrolyte membrance forms, and negative electrode and anode each lead at electrolyte membrance both sides, fuel and oxidant respectively In anode and cathode chamber, and electrochemical reaction occurring, produce electric energy and heat, battery operating temperature exists 650 DEG C, the scale of battery is amplified by multiple battery pile connection in series-parallel.

One the most according to claim 1 can realize the front CO that burns₂The integral coal gasification fuel of trapping Battery generating system, it is characterised in that: described compressor (14), turbine (17) and electromotor (18) peace Installing on same axis, turbine (17) rotational band under the impact of pressure high temperature hot gas moves compressor (14) Rotating with electromotor (18) 8, compressor (14) makes the pressure of air be increased to more than 4Mpa by normal pressure, Electromotor (18) then produces AC energy.