CN111525154A - A fuel cell and heat engine hybrid power generation system and its working method - Google Patents

Abstract

The invention discloses a hybrid power generation system of a fuel cell and a heat engine. The power generation system has a capacity of 1-100 megawatts, and includes a reformer, a phosphoric acid fuel cell, a solid oxide fuel cell, a combustion chamber, a compressor, and a low-temperature heat recovery device. heat exchangers, low temperature heat exchangers, cooling medium pumps, high temperature regenerators, high temperature heat exchangers, turbines and precoolers. The invention can efficiently utilize the waste heat of the phosphoric acid fuel cell and the waste heat of the solid oxide fuel cell, and provide the waste heat of the phosphoric acid fuel cell and the waste heat of the solid oxide fuel cell to the power generation system of the supercritical carbon dioxide cycle as a heat engine, and the total power generation of the system The efficiency can reach more than 60%.

Description

A fuel cell and heat engine hybrid power generation system and its working method

technical field

The invention relates to the technical field of power generation, in particular to a hybrid power generation system of a fuel cell and a heat engine and a working method thereof.

Background technique

With the continuous advancement of the hydrogen energy industry, fuel cell technology is also increasingly developed and mature. Among the various types of fuel cells, the most striking are proton exchange membrane fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, and solid oxide fuel cells. Since proton exchange membrane fuel cells can provide high power density at a reasonable operating temperature (about 80 °C), they are mainly aimed at application requirements in the transportation field. Since phosphoric acid fuel cells and molten carbonate fuel cells have lower power densities than proton exchange membrane fuel cells, they were mainly developed for stationary applications.

Currently, SOFCs with efficiencies of over 50% are being developed for stationary and transportation applications, but with operating temperatures as high as 800-1000°C, stationary applications are more suitable. Phosphoric acid fuel cell is the most mature technology among all fuel cells. It can manufacture power generation devices of various specifications ranging from tens of kilowatts to tens of megawatts. It is the fuel cell product with the largest application outside the transportation field. The amount is increasing year by year. The efficiency of phosphoric acid fuel cells is about 40-50%, and the operating temperature is about 200 ° C. The waste heat generated during operation needs to be discharged and utilized, which can be used for heat supply or waste heat power generation to improve energy utilization. The working temperature of the solid oxide fuel cell is high, and the temperature of the exhaust gas can be as high as 800 °C. The heat engine is used to generate electricity to efficiently utilize the waste heat. Since the waste heat of phosphoric acid fuel cells and solid oxide fuel cells has high temperature and large heat, more sufficient and efficient utilization will bring considerable economic efficiency.

In recent years, the supercritical carbon dioxide cycle technology has been continuously developed and matured, and its potential advantages have also been emerging. Carbon dioxide has stable chemical properties, high density, non-toxicity, low cost, simple circulation system, compact structure, high efficiency, and air-cooling. The supercritical carbon dioxide cycle can be combined with various heat sources to form a power generation system, so it has a very wide range of application scenarios. , including large centralized power plants and small distributed power plants. In the supercritical carbon dioxide cycle with a simple regenerative arrangement, due to the large specific heat and low temperature of the working fluid at the compressor outlet, a low-grade heat source below 200°C can be used as a component of the heat source, and the phosphoric acid fuel cell has exactly this temperature of waste heat. The waste heat temperature of solid oxide fuel cells is high, and it is suitable as a high temperature heat source for supercritical carbon dioxide cycle. Therefore, the supercritical carbon dioxide cycle system can provide a new way for the efficient utilization of waste heat of phosphoric acid fuel cells and waste heat of solid oxide fuel cells.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the prior art, the purpose of the present invention provides a kind of reasonable design, simple structure, simple control, can efficiently utilize the waste heat of the phosphoric acid fuel cell and the waste heat of the solid oxide fuel cell, and combine the waste heat of the phosphoric acid fuel cell with the waste heat of the solid oxide fuel cell. The waste heat of the solid oxide fuel cell is supplied to the power generation system of the supercritical carbon dioxide cycle as a heat engine, and the total power generation efficiency of the system can reach more than 60% of the fuel cell and heat engine hybrid power generation system.

In order to solve the above technical problems, the present invention adopts the following technical solutions to realize:

A fuel cell and heat engine hybrid power generation system, characterized in that it includes

A reformer for hydrogen production by reforming the fuel and water, an inlet of the reformer is communicated with the water source, and the other inlet of the reformer is communicated with the fuel source;

A phosphoric acid fuel cell for generating electricity, the air inlet of the phosphoric acid fuel cell is communicated with the air, and the fuel inlet of the phosphoric acid fuel cell is communicated with the hydrogen-rich gas product outlet of the reformer;

A solid oxide fuel cell for generating electricity, the air inlet of the solid oxide fuel cell is in communication with the air, and the fuel inlet of the solid oxide fuel cell is in communication with the hydrogen-rich gas product outlet of the reformer;

a combustion chamber for burning the exhaust gas discharged from the solid oxide fuel cell, the inlet of the combustion chamber is communicated with the exhaust gas outlet of the solid oxide fuel cell;

a compressor for compressing the carbon dioxide working medium;

a low-temperature regenerator for heating the carbon dioxide working medium pressurized by the compressor, the low-temperature side inlet of the low-temperature regenerator is communicated with the outlet of the compressor;

A low-temperature heat exchanger for heating the carbon dioxide working medium pressurized by the compressor, the low-temperature side inlet of the low-temperature heat exchanger is communicated with the compressor outlet, and the high-temperature side inlet of the low-temperature heat exchanger is connected Connected with the cooling medium outlet of the phosphoric acid fuel cell;

a cooling medium pump for driving the cooling medium to circulate, the outlet of the cooling medium pump is communicated with the cooling medium inlet of the phosphoric acid fuel cell, and the inlet of the cooling medium pump is communicated with the high temperature side outlet of the low temperature heat exchanger;

A high temperature regenerator for further heating the carbon dioxide working medium heated by the low temperature regenerator, the low temperature side inlet of the high temperature regenerator is respectively connected with the low temperature side outlet of the low temperature regenerator and the low temperature side of the low temperature heat exchanger. The side outlet is connected, and the high temperature side outlet of the high temperature regenerator is connected with the high temperature side inlet of the low temperature regenerator;

A high temperature heat exchanger for reheating the carbon dioxide working medium heated by the high temperature regenerator, the low temperature side inlet of the high temperature heat exchanger is communicated with the low temperature side outlet of the high temperature regenerator, the high temperature The high temperature side inlet of the heat exchanger is communicated with the outlet of the combustion chamber;

A turbine for providing power, the inlet of the turbine is communicated with the outlet of the low temperature side of the high temperature heat exchanger, the outlet of the turbine is communicated with the inlet of the high temperature side of the high temperature regenerator, the turbine is used for to drive generators to generate electricity;

A precooler for cooling the carbon dioxide working medium at the high temperature side outlet of the low temperature regenerator, the inlet of the precooler is communicated with the high temperature side outlet of the low temperature regenerator, and the outlet of the precooler is connected to the high temperature side outlet of the low temperature regenerator. The inlet of the compressor is connected.

In a preferred embodiment of the present invention, the fuel of the reformer can be any one of natural gas, coal gas and methanol.

In a preferred embodiment of the present invention, the reforming reaction process of the reformer adopts steam reforming or partial oxidation reforming process.

In a preferred embodiment of the present invention, the pressure at the outlet of the compressor is 15-25 Mpa.

In a preferred embodiment of the present invention, the inlet temperature of the turbine is 500-750°C.

In a preferred embodiment of the present invention, the gas waste heat at the high temperature side outlet of the high temperature heat exchanger can preheat the air and hydrogen-rich gas used to enter the solid oxide fuel cell.

A working method of a fuel cell and heat engine hybrid power generation system, the working method adopts the fuel cell and heat engine hybrid power generation system to operate, comprising the following steps:

S1: fuel and water are sent to the reformer to produce hydrogen, and the reformer produces a hydrogen-rich gas product, which is respectively delivered to the phosphoric acid fuel cell and the solid oxide fuel cell;

S2: The phosphoric acid fuel cell generates electricity and generates waste heat, the solid oxide fuel cell generates electricity, and the exhaust gas enters the combustion chamber for further combustion to generate heat;

S3: The carbon dioxide working medium is pressurized by the compressor and divided into two paths, one of which enters the low-temperature regenerator to absorb the waste heat of the carbon dioxide working medium discharged from the turbine, and the other enters the low-temperature heat exchanger to absorb the waste heat discharged from the phosphoric acid fuel cell;

S4: then merge the heated two-way carbon dioxide working medium and enter the high temperature regenerator to absorb the waste heat of the carbon dioxide working medium discharged by the turbine;

S5: The carbon dioxide working medium heated by the high temperature regenerator then enters the high temperature heat exchanger to absorb the heat of the exhaust gas of the solid oxide fuel cell, and finally enters the turbine for expansion to do work, and the exhaust gas discharged from the high temperature heat exchanger can be used for preheating into the solid oxide fuel cell Air and fuel for fuel cells;

S6: The carbon dioxide working medium discharged from the turbine releases heat through the high temperature regenerator and the low temperature regenerator, and then is cooled to normal temperature by the precooler, and finally returns to the compressor.

Compared with the prior art, the invention can efficiently utilize the waste heat of the phosphoric acid fuel cell and the waste heat of the solid oxide fuel cell, and provide the waste heat of the phosphoric acid fuel cell and the waste heat of the solid oxide fuel cell to the supercritical carbon dioxide cycle as a heat engine. The power generation system adopts the supercritical carbon dioxide cycle in a simple regenerative mode, making full use of the waste heat of phosphoric acid fuel cells and solid oxide fuel cells, and the total power generation efficiency of the system can reach more than 60%.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

Fig. 1 is a control principle diagram of the present invention.

Detailed ways

In order to make it easy to understand the technical means, creation features, achieved goals and effects of the present invention, the present invention will be further described below with reference to the specific figures.

Referring to FIG. 1, a fuel cell and heat engine hybrid power generation system has a capacity of 1 to 100 MW, including a reformer 100, a phosphoric acid fuel cell 200, a solid oxide fuel cell 300, a combustion chamber 400, Compressor 500 , low temperature regenerator 600 , low temperature heat exchanger 700 , cooling medium pump 800 , high temperature regenerator 900 , high temperature heat exchanger 1000 , turbine 1100 , generator 1200 and precooler 1300 .

The reformer 100 is used for the reformation reaction of fuel and water to produce hydrogen. One inlet of the reformer 100 is communicated with the water source, and the other inlet of the reformer 100 is communicated with the fuel source. In this embodiment, the reformer The fuel of the device 100 can be any one of natural gas, coal gas and methanol, and the reforming reaction process of the reforming device 100 adopts steam reforming or partial oxidation reforming process.

The phosphoric acid fuel cell 200 is used for generating electricity, the air inlet of the phosphoric acid fuel cell 200 is communicated with the air, the fuel inlet of the phosphoric acid fuel cell 200 is communicated with the hydrogen-rich gas product outlet of the reformer 100, and the solid oxide fuel cell 300 is used for To generate electricity, the air inlet of the solid oxide fuel cell 300 is communicated with the air, and the fuel inlet of the solid oxide fuel cell 300 is communicated with the hydrogen-rich gas product outlet of the reformer 100 .

The combustion chamber 400 is used for burning the exhaust gas discharged from the solid oxide fuel cell 300, the inlet of the combustion chamber 400 is communicated with the exhaust gas outlet of the solid oxide fuel cell 300, and the compressor 500 is used for compressing the carbon dioxide working medium. In this embodiment, the pressure at the outlet of the compressor 500 is 15-25 Mpa.

The low temperature regenerator 600 is used to heat the carbon dioxide working medium after being pressurized by the compressor 500. The low temperature side inlet of the low temperature regenerator 600 is connected to the outlet of the compressor 500, and the low temperature heat exchanger 700 is used to heat the compressed air. The pressurized carbon dioxide working medium of the compressor 500 is heated, the low temperature side inlet of the low temperature heat exchanger 700 is connected with the outlet of the compressor 500, and the high temperature side inlet of the low temperature heat exchanger 700 is connected with the cooling medium outlet of the phosphoric acid fuel cell 200. .

The cooling medium pump 800 is used to drive the cooling medium to circulate.

The high temperature regenerator 900 is used to further heat the carbon dioxide working medium heated by the low temperature regenerator 600 . The low temperature side outlet is communicated, and the high temperature side outlet of the high temperature regenerator 900 is communicated with the high temperature side inlet of the low temperature regenerator 600 .

The high temperature heat exchanger 1000 is used to reheat the carbon dioxide working medium heated by the high temperature regenerator 900. The low temperature side inlet of the high temperature heat exchanger 1000 is communicated with the low temperature side outlet of the high temperature regenerator 900, and the high temperature heat exchange The high temperature side inlet of the burner 1000 communicates with the outlet of the combustion chamber 400 .

The turbine 1100 is used to provide power, the inlet of the turbine 1100 is connected to the outlet of the low temperature side of the high temperature heat exchanger 1000, the outlet of the turbine 1100 is connected to the inlet of the high temperature side of the high temperature regenerator 1000, and the turbine 1100 is used to propel The generator 1200 generates electricity. In this embodiment, the inlet temperature of the turbine 1100 is 500-750°C.

The precooler 1300 is used to cool the carbon dioxide working medium at the high temperature side outlet of the low temperature regenerator 600, the inlet of the precooler 1300 is communicated with the high temperature side outlet of the low temperature regenerator 600, and the outlet of the precooler 1300 is connected to the compressor The inlet of the machine 500 is connected.

The invention also discloses a working method of a fuel cell and a heat engine hybrid power generation system, the working method comprising the following steps:

S1: the fuel and water are sent to the reformer 100 to produce hydrogen, and the reformer 100 produces a hydrogen-rich gas product, which is respectively delivered to the phosphoric acid fuel cell 200 and the solid oxide fuel cell 300;

S2: the phosphoric acid fuel cell 200 generates electricity and generates waste heat, the solid oxide fuel cell 300 generates electricity, and the exhaust gas enters the combustion chamber 400 for further combustion to generate heat;

S3: The carbon dioxide working medium is pressurized by the compressor 500 and divided into two paths, one path enters the low temperature regenerator 600 to absorb the waste heat of the carbon dioxide working medium discharged from the turbine 1100, and the other path enters the low temperature heat exchanger 700 to absorb the waste heat discharged from the phosphoric acid fuel cell 200. ;

S4: then merge into the high temperature regenerator 900 through the heated two-way carbon dioxide working medium and absorb the waste heat of the carbon dioxide working medium discharged by the turbine 1100;

S5: The carbon dioxide working medium heated by the high temperature regenerator 900 then enters the high temperature heat exchanger 1000 to absorb the heat of the exhaust gas of the solid oxide fuel cell 300, and finally enters the turbine 1100 to expand and perform work, and the exhaust gas discharged from the high temperature heat exchanger 1000 can be used for preheating heat entering the air and fuel of the solid oxide fuel cell 300;

S6: The carbon dioxide working medium discharged from the turbine 1100 releases heat through the high temperature regenerator 900 and the low temperature regenerator 600, and is cooled to normal temperature by the precooler 1300, and finally returns to the compressor 500.

To sum up, if the present invention adopts the parameters in Table 1

Table 1

Then the supercritical carbon dioxide cycle power generation efficiency is 39.5%, the waste heat absorbed from the phosphoric acid fuel cell is 0.84MW, and the waste heat absorbed from the solid oxide fuel cell is 1.70MW.

Given that the power generation efficiency of the phosphoric acid fuel cell is 40%, the fuel calorific value consumed by the phosphoric acid fuel cell is 1.40MW, and the power generation is 0.56MW.

Given that the solid oxide fuel cell efficiency is 50%, the fuel calorific value consumed by the solid oxide fuel cell is 3.40MW, and the power generation is 1.70MW.

The thermal efficiency of the given reformer is 90%.

Then the overall power generation efficiency of the whole system is estimated to be 61.1%.

In summary, the present invention can efficiently utilize the waste heat of the phosphoric acid fuel cell and the waste heat of the solid oxide fuel cell, and provide the waste heat of the phosphoric acid fuel cell and the waste heat of the solid oxide fuel cell to the power generation system of the supercritical carbon dioxide cycle as a heat engine, The supercritical carbon dioxide cycle in the simple regenerative mode is adopted, and the waste heat of phosphoric acid fuel cells and solid oxide fuel cells is fully utilized, and the total power generation efficiency of the system can reach more than 60%.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the present invention. Such changes and improvements fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (7)

1. A fuel cell and heat engine hybrid power generation system is characterized in that, comprising A reformer for hydrogen production by reforming the fuel and water, an inlet of the reformer is communicated with the water source, and the other inlet of the reformer is communicated with the fuel source; A phosphoric acid fuel cell for generating electricity, the air inlet of the phosphoric acid fuel cell is communicated with the air, and the fuel inlet of the phosphoric acid fuel cell is communicated with the hydrogen-rich gas product outlet of the reformer; A solid oxide fuel cell for generating electricity, the air inlet of the solid oxide fuel cell is in communication with the air, and the fuel inlet of the solid oxide fuel cell is in communication with the hydrogen-rich gas product outlet of the reformer; a combustion chamber for burning the exhaust gas discharged from the solid oxide fuel cell, the inlet of the combustion chamber is communicated with the exhaust gas outlet of the solid oxide fuel cell; a compressor for compressing the carbon dioxide working medium; a low-temperature regenerator for heating the carbon dioxide working medium pressurized by the compressor, the low-temperature side inlet of the low-temperature regenerator is communicated with the outlet of the compressor; A low-temperature heat exchanger for heating the carbon dioxide working medium pressurized by the compressor, the low-temperature side inlet of the low-temperature heat exchanger is communicated with the compressor outlet, and the high-temperature side inlet of the low-temperature heat exchanger is connected Connected with the cooling medium outlet of the phosphoric acid fuel cell; a cooling medium pump for driving the cooling medium to circulate, the outlet of the cooling medium pump is communicated with the cooling medium inlet of the phosphoric acid fuel cell, and the inlet of the cooling medium pump is communicated with the high temperature side outlet of the low temperature heat exchanger; A high temperature regenerator for further heating the carbon dioxide working medium heated by the low temperature regenerator, the low temperature side inlet of the high temperature regenerator is respectively connected with the low temperature side outlet of the low temperature regenerator and the low temperature side of the low temperature heat exchanger. The side outlet is connected, and the high temperature side outlet of the high temperature regenerator is connected with the high temperature side inlet of the low temperature regenerator; A high temperature heat exchanger for reheating the carbon dioxide working medium heated by the high temperature regenerator, the low temperature side inlet of the high temperature heat exchanger is communicated with the low temperature side outlet of the high temperature regenerator, the high temperature The high temperature side inlet of the heat exchanger is communicated with the outlet of the combustion chamber; A turbine for providing power, the inlet of the turbine is communicated with the outlet of the low temperature side of the high temperature heat exchanger, the outlet of the turbine is communicated with the inlet of the high temperature side of the high temperature regenerator, the turbine is used for to drive generators to generate electricity; A precooler for cooling the carbon dioxide working medium at the high temperature side outlet of the low temperature regenerator, the inlet of the precooler is communicated with the high temperature side outlet of the low temperature regenerator, and the outlet of the precooler is connected to the high temperature side outlet of the low temperature regenerator. The inlet of the compressor is connected. 2 . The hybrid power generation system of a fuel cell and a heat engine according to claim 1 , wherein the fuel of the reformer can be selected from any one of natural gas, coal gas and methanol. 3 . 3 . The hybrid power generation system of a fuel cell and a heat engine according to claim 1 , wherein the reforming reaction process of the reformer adopts steam reforming or partial oxidation reforming process. 4 . 4 . The hybrid power generation system of a fuel cell and a heat engine according to claim 1 , wherein the pressure at the outlet of the compressor is 15-25 Mpa. 5 . 5 . The hybrid power generation system of a fuel cell and a heat engine according to claim 1 , wherein the inlet temperature of the turbine is 500-750° C. 6 . 6 . The hybrid power generation system of fuel cell and heat engine according to claim 1 , wherein the gas waste heat from the high temperature side outlet of the high temperature heat exchanger can affect the air and richness of the air entering the solid oxide fuel cell. 7 . Hydrogen gas is preheated. 7. A working method of a fuel cell and heat engine hybrid power generation system, the working method using the fuel cell and heat engine hybrid power generation system as claimed in any one of claims 1-6 to operate, comprising the following steps: S1: fuel and water are sent to the reformer to produce hydrogen, and the reformer produces a hydrogen-rich gas product, which is respectively delivered to the phosphoric acid fuel cell and the solid oxide fuel cell; S2: The phosphoric acid fuel cell generates electricity and generates waste heat, the solid oxide fuel cell generates electricity, and the exhaust gas enters the combustion chamber for further combustion to generate heat; S3: The carbon dioxide working medium is pressurized by the compressor and divided into two paths, one of which enters the low-temperature regenerator to absorb the waste heat of the carbon dioxide working medium discharged from the turbine, and the other enters the low-temperature heat exchanger to absorb the waste heat discharged from the phosphoric acid fuel cell; S4: then merge the heated two-way carbon dioxide working medium and enter the high temperature regenerator to absorb the waste heat of the carbon dioxide working medium discharged by the turbine; S5: The carbon dioxide working medium heated by the high temperature regenerator then enters the high temperature heat exchanger to absorb the heat of the exhaust gas of the solid oxide fuel cell, and finally enters the turbine for expansion to do work, and the exhaust gas discharged from the high temperature heat exchanger can be used for preheating into the solid oxide fuel cell Air and fuel for fuel cells; S6: The carbon dioxide working medium discharged from the turbine releases heat through the high temperature regenerator and the low temperature regenerator, and then is cooled to normal temperature by the precooler, and finally returns to the compressor.

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