CN-117525510-B - Method and system for generating power by high-efficiency methanol reforming fuel cell based on normal-temperature PEMFC

CN117525510BCN 117525510 BCN117525510 BCN 117525510BCN-117525510-B

Abstract

The invention relates to a method and a system for generating power by using a high-efficiency methanol reforming fuel cell based on normal-temperature PEMFC, and belongs to the technical field of fuel cells. A high-efficiency methanol reforming fuel cell power generation method based on normal-temperature PEMFC takes methanol solution and high-purity methanol as input, and comprises the steps of directly introducing the methanol solution into a fuel cell anode after reforming and purifying, carrying out catalytic combustion reaction on the high-purity methanol, using reaction heat for reforming the methanol solution, directly introducing air into a fuel cell cathode after pressurizing and humidifying, and using cooling working medium for cooling the fuel cell after pressurizing. The invention has the advantages of high power density, compact structure, quick start and the like of the normal-temperature PEMFC system, has the characteristics of high stability, high overall efficiency and system simplification of the high-temperature HPEMFC system, can be used in more fields and in environments with higher power generation level requirements, and has better low-temperature storage and start adaptability.

Inventors

WANG HANLIN
MA ZE
YUAN HONGSHENG

Assignees

北京机械设备研究所

Dates

Publication Date: 20260512
Application Date: 20220729

Claims (3)

1. The method for generating the power by using the high-efficiency methanol reforming fuel cell based on the normal-temperature PEMFC is characterized by taking a methanol solution and high-purity methanol as inputs, and comprises the following steps: The methanol solution is directly introduced into the anode of the fuel cell after being reformed and purified; The high-purity methanol is subjected to catalytic combustion reaction, and the reaction heat is used for reforming the methanol solution; The air is directly introduced into the cathode of the fuel cell after being pressurized and humidified; the cooling working medium is pressurized and then used for cooling the fuel cell; The methanol solution is directly introduced into the anode of the fuel cell after being reformed and purified, and comprises the following steps: Pressurizing, cooling, vaporizing and heating the methanol solution to a reforming temperature to obtain crude reformed gas, performing low-temperature conversion on the crude reformed gas to obtain crude purified gas, performing cooling and PROX reaction on the crude purified gas to obtain refined purified gas, and directly introducing the refined purified gas into the anode of the fuel cell for electrochemical reaction after buffering; The high-purity methanol is subjected to catalytic combustion reaction, and the reaction heat is used for reforming a methanol solution, wherein the reaction heat comprises the steps of pressurizing, vaporizing and heating the high-purity methanol and then carrying out combustion reaction with fuel cell tail gas; the high-purity methanol generates high-temperature combustion flue gas through catalytic combustion reaction, and the high-temperature combustion flue gas is divided into a first branch and a second branch; the high-temperature combustion flue gas of the first branch is used for providing heat for reforming the methanol solution; the high-temperature combustion flue gas of the second branch is used for heating a cooling working medium in the cooling unit; The air is directly introduced into the cathode of the fuel cell after being pressurized and humidified, and comprises three branches after being compressed, pressurized and intercooled; The first branch is a main air path, the first branch is humidified and enters a cathode of the fuel cell to perform electrochemical reaction, the generated high-humidity cathode tail gas is used for humidifying air again, meanwhile, the high-humidity cathode tail gas is mixed with refined gas and anode tail gas generated after the anode reaction of the fuel cell, the mixed tail gas is heated and then serves as an oxidant to perform combustion reaction with high-purity methanol, and meanwhile, liquid water of an electrochemical reaction product carried out by the cathode gas is separated and discharged; the second branch air participates in the purification reaction of the crude purified gas; the third branch air is Air Bleed air paths, and after being fully mixed with refined gas, the third branch air enters the anode of the fuel cell to participate in the reaction; The cooling working medium is pressurized and then used for cooling the fuel cell, wherein the cooling working medium is respectively supplied to the fuel cell and the intercooler after being pressurized, the cooling working medium can be recycled through the cooling unit, and the cooling working medium exchanges heat with high-temperature combustion flue gas generated by the catalytic combustion reaction of the high-purity methanol through the second heat exchanger, and the cooling working medium after heat exchange heats the fuel cell stack to realize normal-temperature and low-temperature start of the system; the realization system for normal temperature and low temperature start comprises: The high-temperature combustion flue gas of the second branch is used for heating and cooling the working medium, the cooling working medium is subjected to temperature adjustment by starting the second heat exchanger, and the second heat exchanger is connected with one electric heater path in parallel so as to realize temperature adjustment and meet the low-temperature starting conditions.
2. The method for generating electricity according to claim 1, wherein the methanol solution is reformed and purified and then directly introduced into the anode of the fuel cell, comprising: The methanol solution is stored in a methanol solution storage tank, sequentially passes through a first buffer tank and a hydrogen cooler after passing through a second peristaltic pump, and is vaporized and heated to the reforming temperature through a first evaporator; The gas at the outlet of the first evaporator enters a reformer for reaction; after the reaction is finished, obtaining crude reformed gas; the crude reformed gas enters a low-temperature shift reactor for crude purification; Cooling the crude purified gas to the temperature required by the PROX reaction through a hydrogen cooler; The cooled crude purified gas enters a PROX reactor for fine purification; the refined gas passes through a second buffer tank and enters the anode of the fuel cell to carry out electrochemical reaction; anode tail gas enters into a tail gas buffer tank mixing with cathode tail gas.
3. The power generation method according to claim 1, wherein the high purity methanol is subjected to a catalytic combustion reaction, and the heat of reaction is used for reforming a methanol solution, comprising: The high-purity methanol is stored in a methanol storage tank, pressurized by a first peristaltic pump and vaporized by a second evaporator; The methanol gas enters a catalytic combustor to carry out combustion reaction with the tail gas of the fuel cell, and the reaction heat is used for supplying heat to a reformer and supplying the heat to a methanol solution for reforming.

Description

Method and system for generating power by high-efficiency methanol reforming fuel cell based on normal-temperature PEMFC Technical Field The invention belongs to the technical field of fuel cells, and relates to a method and a system for generating power by using a high-efficiency methanol reforming fuel cell based on normal-temperature PEMFC. Background The hydrogen energy is used as a clean and efficient energy source, has high energy density, can be stored and transported, has wide sources, adopts water as a product, has no pollution and zero carbon emission, and gradually becomes the development trend of the global future energy field. Hydrogen energy production and hydrogen fuel cell technology is a key technology for hydrogen energy utilization, and is a serious issue in the development of hydrogen energy technology. In recent years, reforming of alcohols to produce hydrogen has been the focus of attention for hydrogen energy production. Methanol reforming Proton Exchange Membrane Fuel Cell (PEMFC) technology is also a relatively viable and safe hydrogen energy power generation technology. The principle of the methanol reforming PEMFC power generation system is that crude hydrogen is obtained by the methanol through a reforming system, pure hydrogen is obtained by purifying the crude hydrogen, and the pure hydrogen passes through a PEMFC (proton exchange membrane fuel cell) to generate electric energy. The normal temperature PEMFC and the high temperature HPEMFC can be classified according to the operating temperature. The normal temperature PEMFC has higher power density, high single pile power, quick start, compact power generation unit, more complex system and process control, low reliability due to low CO tolerance, larger energy internal consumption and lower overall thermal and electrical efficiency. The whole high-temperature HPEMFC has higher electromechanical efficiency which can reach more than 45%, but is limited by membrane electrode technology, the current HPEMFC has lower power density, the power of a single electric pile is very limited, a plurality of electric piles can be needed to be overlapped when a large-scale system or a hydrogen fuel automobile engine is integrated, and the whole system is heavy. In addition, the high-temperature operation is accompanied with the problems of long starting time and the like. The two common problems are faced with the problems of low-temperature storage, difficult low-temperature starting, energy storage battery and the like. Disclosure of Invention In view of the above analysis, the embodiment of the invention aims to provide a high-efficiency methanol reforming fuel cell power generation system based on a normal-temperature PEMFC, which at least solves one of the following technical problems that 1, the whole machine of the existing methanol reforming normal-temperature PEMFC power generation system is low in heat efficiency, the system is easy to poison, 2, a high-temperature HPEMFC system is low in power density, the system is heavy, 3, the low-temperature storage and low-temperature starting which are faced by the commonality of the two are difficult to use an energy storage battery and the like. The invention is suitable for application scenes of more than 10-30 kW of power levels such as hydrogen fuel cell vehicles, large-scale cogeneration and emergency power supply systems and the like. The aim of the invention is mainly realized by the following technical scheme: In one aspect, the invention provides a method for generating power by using a high-efficiency methanol reforming fuel cell based on normal-temperature PEMFC, which takes methanol solution and high-purity methanol as input, and comprises the following steps: The methanol solution is directly introduced into the anode of the fuel cell after being reformed and purified; The high-purity methanol is subjected to catalytic combustion reaction, and the reaction heat is used for reforming the methanol solution; The air is directly introduced into the cathode of the fuel cell after being pressurized and humidified; the cooling working medium is pressurized and then used for cooling the fuel cell. The method comprises the steps of pressurizing, cooling, vaporizing and heating the methanol solution to a reforming temperature to obtain crude reformed gas, performing low-temperature conversion on the crude reformed gas to obtain crude purified gas, cooling the crude purified gas, performing PROX reaction to obtain refined purified gas, and directly introducing the refined purified gas into the anode of the fuel cell for electrochemical reaction after buffering. Further, the high-purity methanol is subjected to catalytic combustion reaction, which comprises the step of carrying out the combustion reaction with the tail gas of the fuel cell after the high-purity methanol is pressurized, vaporized and heated. Further, the high-purity methanol generates high-temperature combustion flue gas thro