CN112864438B - High temperature fuel cell coupled power generation system and method capable of carbon dioxide capture - Google Patents

Abstract

The invention relates to the field of fuel cell power generation, and discloses a high-temperature fuel cell coupled power generation system capable of capturing carbon dioxide. The coupled power generation system generates power by coupling a solid oxide fuel cell and a molten carbonate fuel cell, and the power generation system comprises: Fine desulfurization tank, SOFC anode heater, air blower, SOFC cathode heater, MCFC anode heater and burner. The invention utilizes that the solid oxide fuel cell cathode oxide can be a substance containing CO ₂ , so that the carbon-containing compounds entering the anode of the solid oxide fuel cell and the anode of the molten carbonate fuel cell enter the burner and burn in the form of CO ₂ . It enters the cathode of the molten carbonate fuel cell for enrichment, improves the reversible voltage of the molten carbonate fuel cell and also increases the concentration of _CO2 , which is convenient for _CO2 capture. Realize the clean, efficient, green and low-carbon development needs of fossil energy.

Description

High temperature fuel cell coupled power generation system and method capable of carbon dioxide capture

technical field

The invention belongs to the field of fuel cell power generation, and in particular relates to a high temperature fuel cell coupled power generation system and method capable of realizing carbon dioxide capture.

Background technique

Fuel cell power generation technology can convert the chemical energy of fossil fuels into electrical energy through electrochemical reactions, so as to meet the needs of clean, efficient, green and low-carbon development of fossil energy. Current high temperature fuel cells can be divided into solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) according to the type of electrolyte. Among them, SOFC has high working efficiency, but it is difficult to enlarge the system capacity, and it generally works at 700℃～800℃; MCFC is easy to enlarge the system capacity, but the working efficiency is low, and generally works at 600℃～700℃.

CN108417876A introduces a high temperature fuel cell coupled power generation system and method, the system includes a fuel purifier, a gas mixer, a heat exchanger, a solid oxide fuel cell, a molten carbonate fuel cell, a fan, a catalytic burner and a DC/ AC converter; the invention also discloses a coupled power generation method of the system; by coupling the solid oxide fuel cell and the molten carbonate fuel cell, the fuel utilization rate in the fuel cell and the power generation efficiency of the system can be improved to a certain extent; Through the arrangement of the heat exchangers in the system, the full utilization of thermal energy can be achieved, and the power generation efficiency and comprehensive energy utilization efficiency of the system can be improved. The system uses secondary fuel and secondary air as supplements to improve the fuel adaptability of the system. Natural gas, coal Gas production, coalbed methane with low calorific value, biomass gas, etc. as fuel.

The high-temperature fuel cell coupled power generation system is a power generation system coupled with a solid oxide fuel cell and a molten carbonate fuel cell. Although the power generation efficiency of the entire system is also improved to a certain extent, because the outlet gas of the solid oxide fuel cell anode is regenerated Passing into the anode of the molten carbonate fuel cell reduces the partial pressure of the effective gases H ₂ , CO, CH ₄ and other gases entering the anode of the molten carbonate fuel cell under the condition of the same amount of fuel gas, which will lead to molten carbonate The fuel cell power generation efficiency is reduced. The use of air as the burner oxidant will reduce the _CO2 concentration entering the cathode of the molten carbonate fuel cell, and at the same time, due to the presence of a large amount of nitrogen in the air, the _CO2 concentration in the combustion exhaust gas will be reduced, increasing the difficulty of _CO2 capture.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the coupling power generation system of the solid oxide fuel cell and the molten carbonate fuel cell in the prior art, since the anode outlet gas of the solid oxide fuel cell is re-introduced into the anode of the molten carbonate fuel cell At the same time, the partial pressure of the effective gases H ₂ , CO and CH ₄ entering the anode side of the molten carbonate fuel cell will be reduced under the condition of the same intake air amount of the fuel, resulting in a decrease in the power generation efficiency of the molten carbonate fuel cell; and Due to the presence of a large amount of N ₂ in the air, using air as the burner oxidant will reduce the concentration of CO ₂ in the combustion exhaust gas, resulting in a decrease in the concentration of CO ₂ entering the cathode of the molten carbonate fuel cell, and increasing the difficulty of CO ₂ capture. The invention provides a high-temperature fuel cell coupled power generation system and method capable of realizing carbon dioxide capture. The coupled power generation system and method can improve the power generation efficiency of the entire system, facilitate CO ₂ capture, and meet the requirements of clean, efficient, and green fossil energy. low-carbon development needs.

In order to achieve the aforementioned object, one aspect of the present invention provides a high-temperature fuel cell coupled power generation system capable of realizing carbon dioxide capture. The coupled power generation system generates power by coupling a solid oxide fuel cell and a molten carbonate fuel cell, and the power generation system includes: Fine desulfurization tanks, solid oxide fuel cells, molten carbonate fuel cells, burners and heat exchange units.

The fine desulfurization tank is respectively communicated with the solid oxide fuel cell and the molten carbonate fuel cell, and provides anode fuel for the solid oxide fuel cell and the molten carbonate fuel cell.

A heat exchange unit is arranged between the fine desulfurization tank and the solid oxide fuel cell, and between the fine desulfurization tank and the molten carbonate fuel cell, and the cathode outlet of the solid oxide fuel cell and the cathode outlet of the molten carbonate fuel cell are provided with heat exchange units. into the heat exchange unit respectively.

The anode outlet of the solid oxide fuel cell and the anode outlet of the molten carbonate fuel cell are respectively communicated with the burner, the burner is communicated with the cathode inlet of the molten carbonate fuel cell, and the burner is connected to the molten carbonate fuel cell. A heat exchange unit is arranged between the fuel cell cathode inlets.

The heat exchange unit enables heat exchange between the pipelines leading to the solid oxide fuel cell and the molten carbonate fuel cell.

Preferably, the heat exchange unit includes SOFC anode heater, SOFC cathode heater and MCFC anode heater, and the SOFC anode heater, SOFC cathode heater and MCFC anode heater are all provided with hot gas passages and cold gas passages , the hot gas channel and the cold gas channel are separated by heat exchange fins and the cold gas channel is heated by the hot gas channel.

The fine desulfurization tank and the solid oxide fuel cell anode inlet are respectively communicated with the cold gas channel of the SOFC anode heater, and the solid oxide fuel cell cathode outlet is communicated with the hot gas channel of the SOFC anode heater , heating the SOFC anode heater cold gas channel through the SOFC anode heater hot gas channel;

The fine desulfurization tank and the anode inlet of the molten carbonate fuel cell are respectively communicated with the cold gas channel of the MCFC anode heater, and the cathode outlet of the MCFC anode heater is communicated with the hot gas channel of the MCFC anode heater , heating the cold gas channel of the MCFC anode heater through the hot gas channel of the MCFC anode heater.

The burner and the molten carbonate fuel cell cathode inlet communicate with the hot gas passage of the SOFC cathode heater.

Preferably, the coupled power generation system is provided with a fan, and the fan and the solid oxide fuel cell cathode inlet are respectively communicated with the cold gas channel of the SOFC cathode heater.

Preferably, the SOFC anode heater is provided with an SOFC cathode tail gas outlet, and the SOFC cathode tail gas outlet and the solid oxide fuel cell cathode outlet are respectively connected to both ends of the hot gas channel of the SOFC anode heater;

The MCFC anode heater is provided with an MCFC cathode tail gas outlet, and the MCFC cathode tail gas outlet and the molten carbonate fuel cell cathode outlet are respectively connected to both ends of the hot gas channel of the MCFC anode heater.

Preferably, the burner is provided with a combustion-supporting pipeline, and a water vapor pipeline is connected between the fine desulfurization tank and the heat exchange unit.

Preferably, the solid oxide fuel cell includes a solid electrolyte, a cathode and an anode respectively disposed on both sides of the solid electrolyte, the fuel enters the anode chamber through the anode inlet of the solid oxide fuel cell, and the oxidant passes through the solid oxide. The cathode inlet of the fuel cell enters the cathode chamber, and the electrochemical reaction occurs to generate electricity and heat;

The molten carbonate fuel cell includes a molten electrolyte and a cathode and an anode respectively disposed on both sides of the molten electrolyte, the fuel enters the anode chamber through the anode inlet of the molten carbonate fuel cell, and the oxidant passes through the molten carbonic acid The cathode inlet of the salt fuel cell enters the cathode chamber, where an electrochemical reaction occurs to generate electricity and heat.

A second aspect of the present invention provides a high-temperature fuel cell coupled power generation method capable of realizing carbon dioxide capture. The method is performed in the above-mentioned coupled power generation system, and the method includes the following steps:

S1, in described fine desulfurization tank, pass into fuel gas desulfurization purification part, the fuel gas after desulfurization purification is divided into SOFC fuel gas and MCFC fuel gas;

S2. SOFC fuel gas is mixed with water vapor in the water vapor pipeline and enters the anode inlet of the solid oxide fuel cell;

S3. The MCFC fuel gas is mixed with the water vapor in the water vapor pipeline and enters the anode inlet of the molten carbonate fuel cell;

S4, SOFC anode tail gas and MCFC anode tail gas are mixed and combusted with the gas in the combustion-supporting pipeline after being passed into the burner to generate combustion tail gas, and the combustion tail gas enters the hot gas channel of the SOFC cathode heater to form the MCFC cathode intake air, and the MCFC cathode intake air is formed. Cathode intake air enters the cathode inlet of the molten carbonate fuel cell;

S5. After the air is introduced into the air fan, the outlet air of the air fan is formed (the outlet air of the air fan exchanges heat with the combustion exhaust gas introduced into the SOFC cathode heater to form the SOFC cathode intake air and enters the cathode inlet of the solid oxide fuel cell.

Preferably, the gas in the combustion-supporting pipeline in the step S4 is oxygen, preferably pure oxygen.

By controlling the amount of oxygen introduced into the combustion-supporting pipeline, high-purity CO ₂ gas can be obtained from the MCFC cathode tail gas outlet; preferably, the excess oxygen introduced into the burner is more than 5%.

Preferably, the main components of the fuel gas in the step S1 are H ₂ and CO gas, and the hydrogen-to-carbon ratio of the fuel gas in the step S1 is preferably 1-3:1.

Preferably, the main components of the SOFC fuel gas and MCFC fuel gas after desulfurization and purification in the step S1 are CO and H ₂ gas and a small amount of CH ₄ and CO ₂ gas.

Through the above technical solutions, a high-temperature fuel cell coupled power generation system capable of realizing carbon dioxide capture of the present invention has the following advantages:

(1) Pass the anode of the solid oxide fuel cell and the anode of the molten carbonate fuel cell into the burner, so that the anode outlet gas of the solid oxide fuel cell and the anode outlet gas of the molten carbonate fuel cell are burned with CO ₂ In the form of carbon dioxide, it enters the cathode of the molten carbonate fuel cell for enrichment, which increases the partial pressure of _CO2 at the cathode of the molten carbonate fuel cell, increases the reversible voltage of the molten carbonate fuel cell, and then improves the efficiency of the entire system;

(2) In the case of the same fuel gas intake amount, the partial pressure of the effective gases H ₂ , CO, CH ₄ and other gases on the anode side of the molten carbonate fuel cell is increased, and the power generation efficiency of the molten carbonate fuel cell is improved, This improves the efficiency of the entire system;

(3) Further, by feeding pure oxygen into the burner for combustion, the amount of oxygen is controlled to obtain high-purity CO ₂ , which facilitates the capture of CO ₂ and meets the clean, efficient, green and low-carbon development needs of fossil energy.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

In the attached image:

1 is a schematic diagram of a high-temperature fuel cell coupled power generation system capable of realizing carbon dioxide capture according to the present invention;

Figure 2 is a schematic diagram of the CN108417876A system.

Description of reference numerals

In Figure 1:

1 Fine desulfurization tank 2 SOFC anode heater

3 Solid oxide fuel cell 4 Air blower

5 SOFC cathode heater 6 MCFC anode heater

7 Molten Carbonate Fuel Cell 8 Burner

101 Fuel gas 102 Water vapor line

103 SOFC anode feed gas mixture 104 SOFC anode feed gas

105 SOFC anode tail gas 106 Air

107 Air blower outlet 108 SOFC cathode inlet

109 SOFC cathode outlet 110 SOFC cathode tail gas outlet

111 SOFC fuel gas 201 MCFC fuel gas

203 MCFC anode feed gas mixture 204 MCFC cathode feed gas

205 MCFC anode exhaust gas 206 Combustion pipeline

207 Combustion exhaust 208 MCFC cathode intake

209 MCFC cathode outlet 210 MCFC cathode exhaust outlet

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

The endpoints of the ranges disclosed herein and any values are not limited to the precise ranges or values, which are to be understood to include values near those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

Referring to FIG. 1, the present invention provides a high-temperature fuel cell coupled power generation system capable of capturing carbon dioxide. The coupled power generation system generates power by coupling a solid oxide fuel cell 3 and a molten carbonate fuel cell 7. The power generation system Including a fine desulfurization tank 1, a solid oxide fuel cell 3, a molten carbonate fuel cell 7, a burner 8 and a heat exchange unit, the fine desulfurization tank 1 is respectively connected with the solid oxide fuel cell 3, the molten carbonate The fuel cell 7 is connected to provide anode fuel for the solid oxide fuel cell 3 and the molten carbonate fuel cell 7, between the fine desulfurization tank 1 and the solid oxide fuel cell 3, and between the fine desulfurization tank 1 and the molten carbonic acid A heat exchange unit is provided between the salt fuel cells 7, and the cathode outlet of the solid oxide fuel cell 3 and the cathode outlet of the molten carbonate fuel cell 7 respectively lead to the heat exchange unit.

The anode outlet of the solid oxide fuel cell 3 and the anode outlet of the molten carbonate fuel cell 7 are respectively communicated with the burner 8, and the burner 8 is communicated with the cathode inlet of the molten carbonate fuel cell 7, and the burner 8 and A heat exchange unit is arranged between the cathode inlets of the molten carbonate fuel cell 7 .

The above-mentioned heat exchange unit can realize heat exchange between the various pipelines leading to the solid oxide fuel cell 3 and the molten carbonate fuel cell 7 .

In a preferred embodiment of the present invention, the heat exchange unit includes an SOFC anode heater 2, an SOFC cathode heater 5 and an MCFC anode heater 6. Wherein, SOFC anode heater 2, SOFC cathode heater 5 and MCFC anode heater 6 are all provided with hot gas channel and cold gas channel, hot gas channel and cold gas channel are separated by heat exchange fins and use hot gas channel to cool the The gas channel is heated.

Specifically, the fine desulfurization tank 1 and the anode inlet of the solid oxide fuel cell 3 are respectively communicated with the cold gas channel of the SOFC anode heater 2, and the cathode outlet of the solid oxide fuel cell 3 is connected with the SOFC anode The hot gas channel of the heater 2 is connected, and the cold gas channel of the SOFC anode heater 2 is heated through the hot gas channel of the SOFC anode heater 2 .

The fine desulfurization tank 1 and the anode inlet of the molten carbonate fuel cell 7 are respectively communicated with the cold gas channel of the MCFC anode heater 6, and the cathode outlet of the MCFC anode heater 6 is connected with the MCFC anode heater 6 The hot gas channel of the MCFC anode heater 6 is connected, and the cold gas channel of the MCFC anode heater 6 is heated through the hot gas channel of the MCFC anode heater 6 .

The outlet of the burner 8 and the inlet of the cathode of the molten carbonate fuel cell 7 are respectively communicated with both ends of the hot gas channel of the SOFC cathode heater 5 .

In a preferred embodiment of the present invention, the coupled power generation system is provided with an air blower 4, the air blower 4 and the cathode inlet of the solid oxide fuel cell 3 are respectively connected with the cold gas passage of the SOFC cathode heater 5 connected at both ends.

In a preferred embodiment of the present invention, the SOFC anode heater 2 is provided with an SOFC cathode tail gas outlet 110 , and the SOFC cathode tail gas outlet 110 and the cathode outlet of the solid oxide fuel cell 3 are respectively connected with the SOFC anode heater 2 Both ends of the hot gas channel are connected;

The MCFC anode heater 6 is provided with an MCFC cathode tail gas outlet 210, and the MCFC cathode tail gas outlet 210 and the cathode outlet of the molten carbonate fuel cell 7 are respectively connected to both ends of the hot gas channel of the MCFC anode heater 6.

In an embodiment of the present invention, the burner 8 is provided with a combustion-supporting pipeline 206, and the combustion-supporting gas in the combustion-supporting pipeline 206 is used to make the material in the burner 8 fully oxidized and burn. A water vapor pipeline 102 is passed between the heat exchange units.

The solid oxide fuel cell 3 includes a solid electrolyte and a cathode and an anode respectively arranged on both sides of the solid oxide fuel cell. The fuel enters the anode chamber through the anode inlet of the solid oxide fuel cell 3, and the oxidant passes through the solid oxide fuel cell. The cathode inlet of 3 enters the cathode chamber, and an electrochemical reaction occurs to generate electricity and heat.

The molten carbonate fuel cell 7 includes a molten electrolyte and a cathode and an anode respectively disposed on both sides of the molten electrolyte. The fuel enters the anode chamber through the anode inlet of the molten carbonate fuel cell 7, and the oxidant passes through the molten carbonate. The cathode inlet of the carbonate fuel cell 7 enters the cathode chamber, and an electrochemical reaction occurs to generate electricity and heat.

According to the present invention, in the above technical solution, the cathode and anode outlet gases of the solid oxide fuel cell 3 and the molten carbonate fuel cell 7 are fully recovered through the SOFC anode heater 2, the SOFC cathode heater 5 and the MCFC anode heater 6 The heat is exchanged for the cold flow at the cathode and anode inlets of the battery, which realizes the heat management of the entire coupled power generation system, and can also realize complete gas startup during the startup process of the coupled power generation system, saving energy and improving the power generation efficiency of the coupled power generation system. .

In the present invention, the fine desulfurization tank is used to desulfurize and purify the fuel gas, and there are no special requirements for it, and no special requirements for the structure of the other units, which are all structures and designs commonly used in the field.

The present invention also provides a high-temperature fuel cell coupled power generation method capable of realizing carbon dioxide capture. The method is performed in the above-mentioned coupled power generation system, and the power generation method includes the following steps:

S1, feed fuel gas 101 into the fine desulfurization tank 1 for desulfurization and purification, and the fuel gas 101 after the desulfurization and purification is divided into SOFC fuel gas 111 and MCFC fuel gas 201;

S2. The SOFC fuel gas 111 is mixed with the water vapor in the water vapor pipeline 102 and enters the anode inlet of the solid oxide fuel cell 3;

S3, the MCFC fuel gas 201 is mixed with the water vapor in the water vapor pipeline 102 and enters the anode inlet of the molten carbonate fuel cell 7;

S4, the SOFC anode tail gas 105 and the MCFC anode tail gas 205 are passed into the burner 8 and then mixed with the gas in the combustion-supporting pipeline 206 to form a combustion tail gas 207, and the combustion tail gas 207 enters the hot gas channel of the SOFC cathode heater 5 to form MCFC Cathode intake 208, the MCFC cathode intake 208 enters the cathode inlet of molten carbonate fuel cell 7;

S5, after the air 106 is introduced into the air blower 4, the air blower outlet gas 107 is formed, and the air blower outlet gas 107 enters the cold gas passage of the SOFC cathode heater 5 and exchanges heat with the combustion exhaust gas 207 introduced into the hot gas passage of the SOFC cathode heater 5 Then, the SOFC cathode intake air 108 is formed, and the SOFC cathode intake air 108 enters the cathode inlet of the solid oxide fuel cell 3 .

Specifically, a fuel gas 101 is connected to the inlet of the fine desulfurization tank 1, and the outlet gas of the fine desulfurization tank 1 is divided into two streams, one is the SOFC fuel gas 111 and the other is the MCFC fuel gas 201. The feed gas 101 of the coupled power generation system can be carbon-based fuels such as syngas, natural gas, etc., to meet the clean, efficient, green and low-carbon development needs of fossil energy.

The SOFC fuel gas 111 is mixed with water vapor and passed into the cold gas channel of the SOFC anode heater 2 and finally enters the anode inlet of the solid oxide fuel cell 3. The MCFC fuel gas 201 is mixed with water vapor and passed into the MCFC anode heater 6 The cold gas channel finally enters the anode inlet of the molten carbonate fuel cell 7 .

Specifically, after mixing the SOFC fuel gas 111 and water vapor, it is passed into the cold gas channel inlet of the SOFC anode heater 2, and the cold gas channel outlet of the SOFC anode heater 2 is passed into the anode inlet of the solid oxide fuel cell 3. The cathode outlet of the oxide fuel cell 3 is connected to the hot gas channel of the SOFC anode heater 2, and the heat exchange between the hot gas channel and the cold gas channel of the SOFC anode heater 2 is carried out to realize the connection to the anode inlet of the solid oxide fuel cell 3. Fuel heating, improve the fuel utilization rate in the solid oxide fuel cell 3, improve the power generation efficiency of the coupled power generation system and the comprehensive utilization rate of heat.

The MCFC fuel gas 201 and the water vapor are mixed and passed into the cold gas channel inlet of the MCFC anode heater 6, the cold gas channel outlet of the MCFC anode heater 6 is passed into the anode inlet of the molten electrolyte fuel cell 7, and the cathode of the molten electrolyte fuel cell 7 The outlet is connected to the hot gas channel of the MCFC anode heater 6, and through the heat exchange between the hot gas channel of the MCFC anode heater 6 and the cold gas channel, the fuel fed into the anode inlet of the molten electrolyte fuel cell 7 is heated, and the molten electrolyte fuel is heated. The fuel utilization rate in the battery 7 improves the power generation efficiency of the coupled power generation system and the comprehensive utilization rate of heat.

The SOFC anode tail gas 105 and the MCFC anode tail gas 205 are passed into the burner 8 and then mixed and combusted with the gas in the combustion-supporting pipeline 206 to generate the combustion tail gas 207, and the combustion tail gas 207 is passed into the hot gas channel inlet of the SOFC cathode heater 5, and the SOFC cathode heater The hot gas channel outlet of 5 leads to the cathode inlet of the molten carbonate fuel cell 7, the air blower outlet gas 107 of the air fan 4 leads to the cold gas channel inlet of the SOFC cathode heater 5, and the cold gas of the SOFC cathode heater 5 The outlet of the gas channel leads to the cathode inlet of the solid oxide fuel cell 3, and the heat exchange between the hot gas channel and the cold gas channel of the SOFC cathode heater 5 is used to realize the heating of the oxidant leading to the cathode inlet of the solid oxide fuel cell 3 .

Under the condition of the same intake amount of the fuel gas 101, the partial pressure of the effective gases CH ₄ , CO and H ₂ at the anode of the molten carbonate fuel cell 7 is increased, and the anode of the solid oxide fuel cell 3 and the molten carbonate fuel cell 7 The carbonaceous compound fuel of the anode enters the molten carbonate fuel cell 7 in the form of _CO2 after combustion, and the cathode is enriched, which increases the reversible voltage of the molten carbonate fuel cell 7 and improves the molten carbonate fuel cell. 7 power generation efficiency, thereby improving the power generation efficiency of the entire coupled power generation system.

In order to increase the pressure of the air blower outlet air 107 of the air blower 4, the air blower 4 is any one of an axial flow blower, a turbo blower or a centrifugal blower.

In a preferred embodiment of the present invention, in the above-mentioned step S4, the gaseous oxygen in the combustion-supporting pipeline 206 passed to the burner 8 is preferably pure oxygen, and the SOFC anode tail gas 105, the MCFC anode tail gas 205 and the Pure oxygen combustion facilitates _CO capture.

In a preferred embodiment of the present invention, in the above step S4, by controlling the amount of oxygen introduced into the combustion-supporting pipeline 206, high-purity CO ₂ gas can be obtained at the MCFC cathode tail gas outlet 210, preferably through the combustion Oxygen excess of device 8 is more than 5%.

In a preferred embodiment of the present invention, the main components of the fuel gas 101 in the step S1 are H ₂ and CO gas, and preferably, the hydrogen-to-carbon ratio of the fuel gas 101 in the step S1 is 1-3:1.

In the above technical solution, it is preferred that the main components of the SOFC fuel gas 111 and MCFC fuel gas 201 after desulfurization and purification in step S1 are CO and H ₂ gas, and also include a small amount of CH ₄ and CO ₂ gas.

The coupled power generation method is suitable for normal pressure and pressurized operation. Specifically, the main reactions that take place inside the solid oxide fuel cell 3 are:

anode:

H ₂ +O ^2- →H ₂ O+2e

CO+O ^2- →CO ₂ +2e

cathode:

O ₂ +4e→2O ^2-

The main reactions that take place inside the molten carbonate fuel cell 7 are:

anode:

H ₂ +CO ₃ ^2- →H ₂ O+CO ₂ +2e

CO+CO ₃ ^2- →2CO ₂ +2e

cathode:

CO ₂ +1/2O ₂ +2e→CO ₃ ^2-

Example 1

In this embodiment, the above-mentioned coupled power generation system and method are used, wherein the components of the fuel gas 101 are H ₂ and CO, the hydrogen-carbon ratio is 1.6:1, and the intake air of the solid oxide fuel cell 3 and the molten carbonate fuel cell 7 is The ratio is 1:1.

Referring to FIG. 1 , the fuel gas 101 is passed into the fine desulfurization tank 1 and the desulfurized and purified synthesis gas is divided into two streams, one of which is SOFC fuel gas 111 and the other is MCFC fuel gas 201 .

The SOFC fuel gas 111 is mixed with the water vapor in the water vapor pipeline 102 to form the SOFC anode feed mixture 103, which is passed into the SOFC anode heater 2, and is heated by the SOFC cathode outlet gas 109 at the cathode outlet of the solid oxide fuel cell 3 to form SOFC The anode feed gas 104 enters the anode inlet of the solid oxide fuel cell 3 , and the SOFC anode tail gas 105 of the solid oxide fuel cell 3 enters the burner 8 .

The other MCFC fuel gas 201 after desulfurization and purification is also mixed with the water vapor in the water vapor pipeline 102 to form the MCFC anode feed mixture 203, which enters the MCFC anode heater 6 and passes through the MCFC at the cathode outlet of the molten carbonate fuel cell 7. The cathode outlet gas 209 is heated to form an MCFC anode feed gas 204 that enters the anode inlet of the molten carbonate fuel cell 7 , and the MCFC anode tail gas 205 from the anode outlet of the molten carbonate fuel cell 7 enters the burner 8 .

SOFC anode tail gas 105 and _MCFC anode tail gas 205 are mixed and combusted with oxygen in burner ₈ to generate combustion tail gas 207 . After heat exchange, the outlet gas 107 of the air blower enters the cathode inlet of the molten carbonate fuel cell 7, and is enriched at the cathode of the molten carbonate fuel cell 7, which increases the concentration of _CO in the cathode of the molten carbonate fuel cell 7. The pressure increases, the reversible voltage of the molten carbonate fuel cell 7 is increased, the power generation efficiency of the molten carbonate fuel cell 7 is improved, and the power generation efficiency of the entire coupled power generation system is further improved.

The setting parameters of the coupled power generation system in this embodiment are shown in Table 1.

Table 1

Solid oxide fuel cell 3 single pass conversion 80% Molten Carbonate Fuel Cell 7 Single Pass Conversion 80%

The efficiency of the coupled power generation system of this embodiment is shown in Table 2.

Table 2

power generation 100kw electrical efficiency 55%

Comparative Example 1

In Fig. 2, 1 is the first fuel purifier, 2 is the second fuel purifier, 3 is the first gas mixer, 4 is the first heat exchanger, 5 is the second heat exchanger, and 6 is the solid oxide fuel cell , 7 is the second gas mixer, 8 is the molten carbonate fuel cell, 9 is the third gas mixer, 10 is the second fan, 11 is the third heat exchanger, 12 is the fourth heat exchanger, 13 is the The first fan, 14 is the fifth heat exchanger, 15 is the sixth heat exchanger, 16 is the catalytic burner, 17 is the first DC/AC converter, and 18 is the second DC/AC converter.

According to the process shown in Figure 2, the primary fuel is passed into the inlet of the first fuel purifier 1, the secondary fuel is passed into the inlet of the second fuel purifier 2; the deionized water is passed into the first heat exchanger 4, it is converted into water vapor; the water vapor at the outlet of the first heat exchanger 4 and the fuel at the outlet of the first fuel purifier 1 are fully mixed in the first gas mixer 3, and then heated up to a temperature of Above 600 ℃, then pass into the anode inlet of the solid oxide fuel cell 6, the internal reforming reaction occurs in the anode chamber of the solid oxide fuel cell 6, the electrochemical reaction occurs in the anode of the solid oxide fuel cell 6, and Electricity is generated; the temperature of the product after the anode reaction of the solid oxide fuel cell 6 is higher than 800 ° C; the anode outlet gas of the solid oxide fuel cell 6 is passed into the second inlet of the second gas mixer 7, and the second fuel purifier 2. The fuel and deionized water at the outlet are fully mixed in the second gas mixer 7, and the mixing temperature is reduced to 600 ° C; the gas at the outlet of the second gas mixer 7 is passed into the anode inlet of the molten carbonate fuel cell 8, The reforming reaction occurs in the anode of the molten carbonate fuel cell 8; an electrochemical reaction occurs in the anode of the molten carbonate fuel cell 8, and electricity is generated; the anode outlet gas of the molten carbonate fuel cell 8 is passed to the third the first inlet of the gas mixer 9;

The primary air is introduced into the first fan 13, and the air pressure at the outlet of the fan is above 1.5 atm. After passing through the fifth heat exchanger 14, the temperature is raised to above 200 °C, and then the temperature is raised to above 600 °C through the sixth heat exchanger 15. Finally, Passed into the cathode inlet of the solid oxide fuel cell 6, the oxygen in the air undergoes an electrochemical reaction at the cathode of the solid oxide fuel cell 6, and the exhaust gas temperature of the solid oxide fuel cell 6 after the reaction is 800 ℃; The cathode outlet gas of the battery 6 is cooled to below 400 ℃ through the fourth heat exchanger 12, and then cooled to below 200 ℃ through the fifth heat exchanger 14, and finally the exhaust gas is discharged to the outside;

The secondary air is introduced into the second fan 10, and the air pressure rises to above 1.5 atm, then passes through the third heat exchanger 11 to rise to above 150 °C, and then passes through the fourth heat exchanger 12 to rise to above 400 °C, and finally passes the temperature. into the second inlet of the third gas mixer 9; in the third gas mixer 9, the secondary air is thoroughly mixed with the anode outlet gas of the molten carbonate fuel cell 8, and then passed into the catalytic burner 16 During the process, a sufficient reaction occurs in the catalytic burner 16; the outlet gas of the catalytic burner 16 is cooled to 550° C. through the sixth heat exchanger 15, and then passed into the cathode inlet of the molten carbonate fuel cell 8; An electrochemical reaction occurs in the cathode of the fuel cell 8; the cathode outlet gas of the molten carbonate fuel cell 8 is cooled to below 400°C through the second heat exchanger 5, and then heated to below 200°C through the third heat exchanger 11, Then, the temperature is lowered to below 100°C through the first heat exchanger 4, and finally the exhaust gas is discharged to the outside; the solid oxide fuel cell 6 outputs DC power, and the first DC/AC converter 17 outputs AC power to the user; the molten carbonate fuel cell 8. Output DC power, and output AC power to the user through the second DC/AC converter 18, see FIG. 2 .

Referring to Fig. 2, Comparative Example 1 adopts a high-temperature fuel cell coupled power generation system shown in Fig. 2. The feed gas composition is H ₂ and CO, and the hydrogen-carbon ratio is about 1.6:1. Carbonate fuel cells have an intake air ratio of 1:1.

The setting parameters of the power generation system in Comparative Example 1 are shown in Table 3.

table 3

Solid oxide fuel cell single pass conversion 80% Molten Carbonate Fuel Cell Single Pass Conversion 80%

The efficiency of the power generation system of Comparative Example 1 is shown in Table 4.

Table 4

power generation 90kw electrical efficiency 50%

It can be seen from the results in Tables 1 to 4 that, compared with Comparative Example 1, Example 1 using the high-temperature fuel cell coupled power generation system and method capable of realizing carbon dioxide capture has the advantages of large power generation and significantly better power generation efficiency. advantage.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (7)

1. A high-temperature fuel cell coupled power generation method capable of realizing carbon dioxide capture, characterized in that the method is performed in a power generation system, and the power generation system comprises a fine desulfurization tank (1), a solid oxide fuel cell (3), a molten carbonate fuel cell (7), a burner (8) and a heat exchange unit; The fine desulfurization tank (1) is connected to the solid oxide fuel cell (3), the molten carbon The acid salt fuel cell (7) communicates with the solid oxide fuel cell (3) and the molten carbonic acid The salt fuel cell (7) provides anode fuel; A heat exchange unit is provided between the fine desulfurization tank (1) and the solid oxide fuel cell (3), and between the fine desulfurization tank (1) and the molten carbonate fuel cell (7). The cathode outlet of the battery (3) and the cathode outlet of the molten carbonate fuel cell (7) are respectively connected to the heat exchange unit; The anode outlet of the solid oxide fuel cell (3) and the anode outlet of the molten carbonate fuel cell (7) are respectively communicated with the burner (8), and the outlet of the burner (8) is connected to the molten carbonate fuel cell (7) The cathode inlet is connected, and a heat exchange unit is arranged between the burner (8) and the cathode inlet of the molten carbonate fuel cell (7); The heat exchange unit enables heat exchange between the pipelines leading to the solid oxide fuel cell (3) and the molten carbonate fuel cell (7); The heat exchange unit includes a SOFC cathode heater (5); the SOFC cathode heater (5) is provided with a hot gas channel and a cold gas channel, the hot gas channel and the cold gas channel are separated by heat exchange fins and utilize the hot gas The channel heats the cold gas channel; The burner (8) and the cathode inlet of the molten carbonate fuel cell (7) are respectively communicated with both ends of the hot gas channel of the SOFC cathode heater (5); The power generation system is provided with an air blower (4), and the air blower (4) and the cathode inlet of the solid oxide fuel cell (3) are respectively communicated with the cold gas passage of the SOFC cathode heater (5); The method includes the following steps: S1, feed fuel gas (101) desulfurization purification into described fine desulfurization tank (1), and the fuel gas (101) after desulfurization and purification is divided into SOFC fuel gas (111) and MCFC fuel gas (201); S2. The SOFC fuel gas (111) is mixed with the water vapor in the water vapor pipeline (102) and enters the anode inlet of the solid oxide fuel cell (3); S3. The MCFC fuel gas (201) is mixed with the water vapor in the water vapor pipeline (102) and enters the anode inlet of the molten carbonate fuel cell (7); S4. The SOFC anode tail gas (105) and the MCFC anode tail gas (205) are passed into the burner (8) and then mixed with the gas in the combustion-supporting pipeline (206) to form combustion tail gas (207), and the combustion tail gas (207) enters The hot gas passage of the SOFC cathode heater (5) forms the MCFC cathode inlet (208), which enters the cathode inlet of the molten carbonate fuel cell (7); S5, the air (106) is introduced into the air blower (4) to form the air blower outlet gas (107), and the air blower outlet gas (107) enters the SOFC cathode heater (5) cold gas channel and is introduced into the SOFC cathode The combustion tail gas (207) of the heater (5) hot gas channel forms an SOFC cathode inlet gas (108) after heat exchange, and the SOFC cathode inlet gas (108) enters the cathode inlet of the solid oxide fuel cell (3); The hydrogen-to-carbon ratio of the fuel gas (101) in the step S1 is 1-3:1; In the step S4, the gas in the combustion-supporting pipeline (206) is pure oxygen; the pure oxygen introduced into the burner (8) exceeds 5% in excess. 2. The coupled power generation method according to claim 1, wherein the heat exchange unit comprises SOFC anode heater (2) and MCFC anode heater (6), the SOFC anode heater Both the heater (2) and the MCFC anode heater (6) are provided with a hot gas channel and a cold gas channel, the hot gas channel and the cold gas channel are separated by heat exchange fins and the cold gas channel is heated by the hot gas channel ; The fine desulfurization tank (1) and the anode inlet of the solid oxide fuel cell (3) are respectively communicated with the cold gas channel of the SOFC anode heater (2), and the cathode outlet of the solid oxide fuel cell (3) communicating with the hot gas channel of the SOFC anode heater (2), and heating the cold gas channel of the SOFC anode heater (2) through the hot gas channel of the SOFC anode heater (2); The anode inlet of the fine desulfurization tank (1) and the molten carbonate fuel cell (7) are respectively communicated with the cold gas channel of the MCFC anode heater (6), and the cathode outlet of the MCFC anode heater (6) It is communicated with the hot gas channel of the MCFC anode heater (6), and the cold gas channel of the MCFC anode heater (6) is heated through the hot gas channel of the MCFC anode heater (6). 3. The coupled power generation method according to claim 2, wherein, The SOFC anode heater (2) is provided with an SOFC cathode tail gas outlet (110), and the SOFC cathode tail gas outlet (110) and the cathode outlet of the solid oxide fuel cell (3) are respectively heated with the SOFC anode heater (2). Both ends of the gas channel are connected; The MCFC anode heater (6) is provided with an MCFC cathode tail gas outlet (210), and the MCFC cathode tail gas outlet (210) and the cathode outlet of the molten carbonate fuel cell (7) are respectively connected with the MCFC anode heater (6) Both ends of the hot gas channel are connected. 4. The coupled power generation method according to claim 1, wherein the burner (8) is provided with a combustion-supporting pipeline (206), and the pipeline between the fine desulfurization tank (1) and the heat exchange unit is connected to the The water vapor line (102) communicates. 5. The coupled power generation method according to claim 1, wherein, The solid oxide fuel cell (3) includes a solid electrolyte and are respectively arranged in the solid electrolyte. Cathode and anode on both sides of the decomposer, the fuel passes through the anode of the solid oxide fuel cell (3) The inlet goes into the anode chamber and the oxidant passes through the cathode of the solid oxide fuel cell (3) The inlet enters the cathode chamber, and an electrochemical reaction occurs to generate electricity and heat; The molten carbonate fuel cell (7) includes a molten electrolyte and are respectively arranged in the molten electrolyte. Cathode and anode on both sides of the decomposer, the fuel passes through the anode of the molten carbonate fuel cell (7) The inlet goes into the anode chamber and the oxidant passes through the cathode of the molten carbonate fuel cell (7) The inlet enters the cathode chamber, where an electrochemical reaction occurs to generate electricity and heat. 6. The coupled power generation method according to claim 1, wherein the main components of the fuel gas (101) in the step S1 are _H2 and CO gas. 7. The coupled power generation method according to claim 1, wherein the main components of the SOFC fuel gas (111) and MCFC fuel gas (201) after desulfurization and purification in the step S1 are CO and H gas and a small amount of _{CH 4.} CO ₂ gas.

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