Fuel cell cogeneration system and control method

Abstract

The present disclosure proposes a fuel cell cogeneration system and control method, the system includes: a fuel cell module unit, a system hydrogen supply circuit, a system main cooling circuit, a system auxiliary heat recovery circuit, an instant heating circuit, and a system water recovery circuit. By providing a chemical reaction site for the fuel cell and inputting hydrogen, the fuel cell module unit is started to produce a chemical reaction, and the heat generated by the chemical reaction of the fuel cell is collected to provide a sufficient heat source for the instant heating circuit through heat exchange, and the fuel cell module unit is dissipated; the heat generated by the fuel cell module unit device is collected, and the heat generated by the device is transferred to the instant heating circuit; according to whether there is heat consumption, different instant heating circuits are switched to achieve flexible heating; and the water generated by the chemical reaction of the fuel cell module unit is collected. While maximizing the use of fuel cell heat and product water and improving resource utilization, the operational flexibility and reliability of the cogeneration system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy utilization, and in particular to a fuel cell cogeneration system and a control method. Background Art

[0002] At present, with the continuous deterioration of the earth's environment and the increasing depletion of fossil resources, countries and organizations around the world are actively exploring sustainable and pollution-free green energy. The related industries and technologies of green energy such as solar energy, wind energy, hydrogen energy, tidal energy, wave energy and nuclear energy have been greatly developed and improved. Among them, hydrogen energy has many advantages such as only water as a combustion product, high calorific value, convenient energy storage and diverse production technologies. Countries have introduced encouraging policies for the hydrogen energy industry, the market has gradually grown, the industrial chain has become more complete, and it has gradually become one of the most important new energy sources.

[0003] Hydrogen has a wide range of uses. Hydrogen is not only an important industrial raw material, but also indispensable in the petrochemical, metallurgical, electronic, food processing and aerospace industries. It also plays an important role in agricultural development, medical research and nuclear energy exploration. Among them, using hydrogen fuel cell systems to convert hydrogen energy into electrical energy and thermal energy for direct consumption is one of the most effective ways to obtain energy by comprehensively utilizing the green and environmentally friendly characteristics of hydrogen energy.

[0004] The hydrogen fuel cell cogeneration system outputs the electrical energy generated by the hydrogen and oxygen electrochemical reaction in the stack, and uses the heat exchange system to exchange the heat energy generated by the reaction for utilization. However, the inventors found that due to the inherent characteristics of the voltage of the single-chip battery in the stack, the size limitations of the bipolar plate or membrane electrode, and the technical level of the stack integration, the power level of a single stack is difficult to reach the application level in the industrial field; such as the patent application number 2023103144526, the patent name is a patent for a proton exchange membrane hydrogen fuel cell cogeneration system, which achieves power expansion by expanding multiple systems, the investment cost is too high, and it is not conducive to the stability of the system. Secondly, in the design of the heating system, it is impossible to achieve the stability of the operating temperature of multiple stacks and maximize the recovery of heat in the battery system by comprehensively considering the battery operating performance and the system heating stability. In addition, in the tail exhaust system, the discharge of air (oxygen) is bound to bring out the product water. If it is not recycled, it will not only increase the processing cost, but also cause waste of water resources. Summary of the invention

[0005] In order to solve the above problems, the present disclosure proposes a fuel cell cogeneration system and control method, which realizes power level expansion by paralleling fuel cell module units and avoids the complexity of system parallel connection; efficiently recovers and utilizes the waste heat of the fuel cell system, simplifies and optimizes the low-temperature cold start problem of the fuel cell, and realizes the uninterrupted supply of regional heat and electricity, alleviating the greenhouse effect to a certain extent; maximizes the utilization of heat and product water through auxiliary heat recovery and tail water recovery, improves resource utilization, and ensures the stable operation of the cogeneration system.

[0006] In order to achieve the above objectives, the present disclosure adopts the following technical solutions:

[0007] A first aspect of the present invention provides a fuel cell cogeneration system, comprising:

[0008] Fuel cell module unit, system hydrogen supply circuit, system main cooling circuit, system auxiliary heat recovery circuit, instant heating circuit, system water recovery circuit;

[0009] The fuel cell module unit provides a place for the chemical reaction of the fuel cell;

[0010] The system hydrogen supply circuit is used to provide the required hydrogen for the chemical reaction of the fuel cell module unit;

[0011] The main cooling loop of the system is used to collect the heat generated by the chemical reaction of the fuel cell, so as to provide sufficient heat source for the instant heating loop through heat exchange, and to dissipate heat for the fuel cell module unit;

[0012] The auxiliary heat recovery loop of the system is used to collect the heat generated by the fuel cell module unit devices and to feed the heat generated by the devices into the instant heating loop;

[0013] The instant heating circuit is used to switch different instant heating circuits to realize flexible heating according to whether there is heating consumption;

[0014] The system water recovery loop is used to collect water generated by the chemical reaction of the fuel cell module units.

[0015] Furthermore, the hydrogen supply circuit of the system includes a hydrogen inlet, a hydrogen supply trunk, a hydrogen supply branch, a hydrogen discharge branch, a tail exhaust trunk, and an exhaust port;

[0016] The hydrogen inlet delivers hydrogen to the hydrogen supply trunk, the hydrogen supply trunk is connected to the hydrogen supply branch, and the hydrogen supply branch is connected to the hydrogen inlet interface of the fuel cell module unit to provide the hydrogen required for the chemical reaction of the fuel cell;

[0017] The hydrogen discharge branch is connected to the exhaust port through the tail exhaust main line, and is used to discharge the excess hydrogen that does not participate in the chemical reaction of the fuel cell and remains in the hydrogen supply circuit of the system.

[0018] Furthermore, the fuel cell module unit includes a hydrogen inlet interface, a tail exhaust interface, a main cooling first interface, a main cooling second interface, an auxiliary cooling first interface, an auxiliary cooling second interface, and a DC / DC output interface.

[0019] Furthermore, the hydrogen inlet interface is connected to the hydrogen inlet in the system hydrogen supply circuit to absorb the hydrogen required for the fuel cell reaction;

[0020] The tail discharge interface is connected to the gas-water separator in the system water recovery loop to recover the water generated by the fuel cell reaction;

[0021] The main cooling first interface is connected to the high-temperature trunk road, and the main cooling second interface is connected to the low-temperature trunk road; the high-temperature trunk road and the low-temperature trunk road are both connected to the primary side of the first plate heat exchanger; the first high-temperature water discharged from the main cooling first interface flows through the high-temperature trunk road to the first plate heat exchanger for heat exchange, and outputs the first low-temperature water, which flows through the low-temperature trunk road and returns to the main cooling second interface;

[0022] The auxiliary cooling first interface is connected to the auxiliary heating high-temperature trunk line, and the auxiliary cooling second interface is connected to the auxiliary heating low-temperature trunk line; the auxiliary heating high-temperature trunk line and the auxiliary heating low-temperature trunk line are both connected to the primary side of the second plate heat exchanger; the second high-temperature water discharged from the auxiliary cooling first interface flows through the auxiliary heating high-temperature trunk line to the second plate heat exchanger for heat exchange, and outputs the second low-temperature water, which returns to the auxiliary cooling second interface;

[0023] The DC / DC output interface is the power output end of the fuel cell.

[0024] Furthermore, at least two fuel cell module units are connected to the busbar via the positive and negative electrodes of the DC / DC output interface to achieve linear expansion of the system power generation;

[0025] The main cooling first interfaces of at least two fuel cell module units are connected to the high-temperature main line, and the main cooling second interfaces are connected to the low-temperature main line, so as to realize the linear expansion of the system heat generation power.

[0026] Further, the main cooling circuit of the system includes a fuel cell module unit, a high-temperature branch, a high-temperature trunk, a first plate heat exchanger, a low-temperature trunk and a low-temperature branch connected in sequence;

[0027] The first plate heat exchanger is used to perform heat exchange on the first high-temperature water discharged from the main cooling first interface of the fuel cell module unit, and output the first low-temperature water back to the main cooling second interface.

[0028] Further, the auxiliary heat recovery circuit of the system includes a fuel cell module unit, an auxiliary heat high temperature branch, an auxiliary heat high temperature trunk, a second plate heat exchanger, an auxiliary heat low temperature trunk and an auxiliary heat low temperature branch connected in sequence, and a buffer tank, an auxiliary heat low temperature secondary trunk, a second plate heat exchanger, an auxiliary heat high temperature secondary trunk, and a third low temperature water flow trunk connected in sequence;

[0029] The second plate heat exchanger is used to exchange heat between the second high-temperature water and the fourth low-temperature water in the auxiliary heating low-temperature secondary trunk line, so that the temperature of the second high-temperature water decreases and the temperature of the fourth low-temperature water increases to fourth high-temperature water; the fourth high-temperature water merges into the third low-temperature water flowing through the trunk line, raising the temperature of the original third low-temperature water, and increasing the circulating water flow rate of the immediate heating circuit while keeping the temperature of the third high-temperature water unchanged.

[0030] Furthermore, the instantaneous heating circuit includes a water inlet, a buffer tank, a first plate heat exchanger, a cooling tower, and a heating port;

[0031] The instant heating circuit includes a first instant heating circuit and a second instant heating circuit;

[0032] If the heat supply port is closed and there is no heat consumption, the water inlet is closed in this state, and the first instant heat supply loop is closed; the first instant heat supply loop includes a buffer tank, a first plate heat exchanger and a cooling tower connected in sequence; the third low-temperature water in the buffer tank is heat exchanged through the secondary side of the first plate heat exchanger, and the third high-temperature water is output to enter the cooling tower for cooling and return to the buffer tank;

[0033] If the heat supply port is open and there is heat consumption, the water inlet is open in this state, and the second instant heating circuit is open; the second instant heating circuit includes a water inlet, a buffer tank, a first plate heat exchanger, and a heat supply port connected in sequence; the water inlet is opened to replenish water to the buffer tank, and the third low-temperature water in the buffer tank is heat exchanged through the secondary side of the first plate heat exchanger, and the third high-temperature water is output and discharged from the heat supply port.

[0034] Furthermore, the system water recovery circuit includes a fuel cell module unit, a tail exhaust branch, a gas-water separator, a tail exhaust trunk, an exhaust port, a water collecting tank, a buffer tank, and a drain port;

[0035] The gas-water separator is used to separate the moisture and gas output from the tail discharge interface, discharge the gas through the exhaust port, collect the moisture in the water collecting tank, and pump it into the buffer tank; when the system has no heating and the liquid levels of the water collecting tank and the buffer tank reach the set upper limit, the moisture is discharged through the drain port.

[0036] A second aspect of the present invention provides a fuel cell cogeneration system control method, comprising the following steps:

[0037] Starting the fuel cell module unit;

[0038] Collect the heat generated by the chemical reaction of the fuel cell and provide sufficient heat source for the instant heating loop through heat exchange;

[0039] Collect the heat generated by the fuel cell module unit devices and send the heat generated by the devices into the instant heating circuit;

[0040] According to whether there is heat consumption, different instantaneous heating circuits are switched to achieve flexible heating;

[0041] Collect water produced by the chemical reaction of the fuel cell module unit.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. Power level can be expanded

[0044] Due to the limitations of technology and system principles, the power of a single fuel cell is limited. A fuel cell system with a megawatt (MW) or even higher power can only be built by connecting multiple systems in parallel. In the parallel connection of systems, the work of laying water and gas lines and integrating components is quite cumbersome, and it is difficult to ensure the unity and coordination of each subsystem. The present invention modularizes the fuel cell, unifies the various specifications and parameters of the modules, simplifies the integration work, reduces the inconsistency of the system, and facilitates the free expansion of power levels.

[0045] 2. Instant heating

[0046] The system's main cooling circuit and instant heating circuit constitute the system's main heating circuit, which is connected to the heating port and the cooling tower. After the system is working, the heating port can provide heat that does not exceed the maximum power at any time; when there is no heat to be used, the system automatically switches to the cooling tower circuit for heat dissipation. The circuit is closed, there is no excess water loss, and no water resource waste will be caused.

[0047] 3. Maximize heat recovery

[0048] In order to recover the unavoidable useless heat energy generated during the operation of BOP (fuel cell) components, the primary and secondary circuits of the plate heat exchanger are used to collect and exchange the heat energy and then merge it into the main heating circuit to maximize the recovery of system heat.

[0049] 4. Tailwater recovery

[0050] The exhaust air of hydrogen fuel cells is bound to be mixed with a large amount of product water. If it is not collected, not only does it require pre-construction of drainage ditches or drainage pipelines at the equipment site, but it is also a waste of water resources. The present invention separates and collects the exhaust air through an air-water separator, and then pumps it into the secondary side water inlet of the main heating line for recycling. This is positive for saving system construction costs and protecting water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and the description thereof are used to explain the present disclosure but do not constitute a limitation of the present disclosure.

[0052] Figure 1 An overall block diagram of a fuel cell cogeneration system provided in Embodiment 1 of the present disclosure;

[0053] Figure 2 A fuel cell module unit provided in the first embodiment of the present disclosure;

[0054] Figure 3 A schematic diagram of power expansion of a fuel cell module unit provided in the first embodiment of the present disclosure;

[0055] Figure 4 A schematic diagram of a fuel cell cogeneration system control method provided in Embodiment 2 of the present disclosure.

[0056] Among them, 11-fuel cell module unit; 111-hydrogen inlet interface; 112-tail exhaust interface; 113-main cooling first interface; 114-main cooling second interface; 115-auxiliary cooling first interface; 116-auxiliary cooling second interface; 117-DC / DC output interface; 201-hydrogen supply hand valve; 202-hydrogen supply main line one-way valve; 203-flame arrester; 204-filter; 205-hydrogen supply main line pressure sensor; 206-flow meter; 207-discharge one-way valve; 208-safety valve; 20 9-main trunk hydrogen release hand valve; 210-hydrogen release branch hand valve; 211-solenoid valve; 212-pressure sensor; 304-first water tank; 305-first deionizer; 306-first ion concentration sensor; 307-first water pump; 308-first filter; 309-second pressure sensor; 310-second temperature sensor; 311-first temperature sensor; 312-first pressure sensor; 313-second hand valve; 314-first hand valve; 401-third hand valve; 40 2-fourth hand valve; 403-first solenoid valve; 404-third solenoid valve; 405-buffer tank; 406-liquid level meter; 407-third temperature sensor; 408-second water pump; 409-first flow meter; 410-cooling tower; 411-second solenoid valve; 501-fourth temperature sensor; 502-third pressure sensor; 503-second water tank; 504-second deionizer; 505-second ion concentration sensor; 506-third water pump; 507-second filter; 508 -Fourth pressure sensor; 509-fifth temperature sensor; 510-fourth solenoid valve; 511-fifth pressure sensor; 512-fourth water pump; 513-fifth hand valve; 514-sixth hand valve; 515-sixth pressure sensor; 516-check valve; 601-seventh hand valve; 602-water collecting tank; 603-liquid level sensor; 604-fifth water pump; 605-third filter; 606-fifth solenoid valve; 607-sixth solenoid valve; 608-seventh solenoid valve; 609 flame arrester. DETAILED DESCRIPTION

[0057] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0058] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0059] Technical term explanation:

[0060] Plate heat exchanger: A high-efficiency heat exchanger made of a series of metal sheets with a certain corrugated shape. Thin rectangular channels are formed between various plates, and liquid-liquid and liquid-gas heat exchange is carried out through the plates, with high heat exchange efficiency and low heat loss.

[0061] Immediacy: The ability of the system to respond within a specified time; applications that require immediacy are characterized by strong activity timeliness, requiring information to be collected from the external environment at a certain moment and within a certain period of time, and then responding in a timely manner. In the present invention, immediacy heat supply is to respond accordingly by switching different circulation loops according to whether there is heat consumption.

[0062] Embodiment 1

[0063] In the technical solution disclosed in one or more embodiments, Figure 1 As shown, a fuel cell cogeneration system comprises:

[0064] Fuel cell module unit, system hydrogen supply circuit, system main cooling circuit, system auxiliary heat recovery circuit, instant heating circuit, system water recovery circuit;

[0065] The fuel cell module unit provides a place for the chemical reaction of the fuel cell;

[0066] The system hydrogen supply circuit is used to provide the required hydrogen for the chemical reaction of the fuel cell module unit;

[0067] The main cooling loop of the system is used to collect the heat generated by the chemical reaction of the fuel cell, so as to provide sufficient heat source for the instant heating loop through heat exchange, and to dissipate heat for the fuel cell module unit;

[0068] The auxiliary heat recovery loop of the system is used to collect the heat generated by the fuel cell module unit devices and to feed the heat generated by the devices into the instant heating loop;

[0069] The instant heating circuit is used to switch different instant heating circuits to realize flexible heating according to whether there is heating consumption;

[0070] The system water recovery loop is used to collect water generated by the chemical reaction of the fuel cell module units.

[0071] The hydrogen fuel cell system is a cogeneration system that converts the chemical energy of hydrogen and air (oxygen) fuel into electrical energy and thermal energy, and the reaction product is water. Based on this principle, the present invention proposes a cogeneration scheme with expandable thermoelectric power levels, maximum recycling of heat and product water, and instant heating of the system.

[0072] In a specific embodiment, the system hydrogen supply circuit includes a hydrogen inlet, a hydrogen supply trunk, a hydrogen supply branch, a hydrogen discharge branch, a tail exhaust trunk, and an exhaust port;

[0073] The hydrogen inlet delivers hydrogen to the hydrogen supply trunk, the hydrogen supply trunk is connected to the hydrogen supply branch, and the hydrogen supply branch is connected to the hydrogen inlet interface of the fuel cell module unit to provide the hydrogen required for the chemical reaction of the fuel cell;

[0074] The hydrogen discharge branch is connected to the exhaust port through the tail exhaust main line, and is used to discharge the excess hydrogen that does not participate in the chemical reaction of the fuel cell and remains in the hydrogen supply circuit of the system.

[0075] Specifically, the hydrogen source supplies hydrogen to the entire system through the hydrogen inlet. After passing through the hydrogen supply manual valve 201, the hydrogen supply main road one-way valve 202, the flame arrester 203, and the filter 204, the branch supplies hydrogen to each module unit; the flow meter 206 and the hydrogen supply main road pressure sensor 205 monitor the flow and pressure of the hydrogen main road. Each branch is controlled by the solenoid valve 211 to control the on-off, and the pressure sensor 212 monitors the pressure; the hydrogen of the corresponding hydrogen supply branch can be manually discharged through the hydrogen discharge branch manual valve 210, and the main road hydrogen discharge manual valve 209 can manually discharge the hydrogen remaining in the hydrogen supply main road; the safety valve 208 automatically discharges the hydrogen remaining in the hydrogen supply main road after detecting that the pressure of the hydrogen supply main road reaches the set threshold to ensure the safety of the system; the residual hydrogen is collected into the tail exhaust main road through the one-way valve 207.

[0076] Taking the fuel cell module unit 11 as an example, some hydrogen that has not entered the stack to participate in the hydrogen-oxygen reaction is retained between the solenoid valve 211 and the pressure sensor 212. However, hydrogen has a low ignition point and a wide explosion limit range, which means that once hydrogen leaks, it may cause combustion or even explosion. Therefore, it is necessary to release the hydrogen retained in the system hydrogen supply circuit in time. Therefore, by opening the manual valve 210, the hydrogen between the solenoid valve 211 and the pressure sensor 212 is discharged from the exhaust port through the hydrogen discharge branch.

[0077] In a specific embodiment, the fuel cell module unit includes a hydrogen inlet interface, a tail exhaust interface, a main cooling first interface, a main cooling second interface, an auxiliary cooling first interface, an auxiliary cooling second interface, and a DC / DC output interface.

[0078] In order to make the overall system thermoelectric power level expandable, this specific embodiment integrates a hydrogen fuel cell stack of a certain specification (such as a power level of 20kW), DC / DC, air filter, humidifier, air compressor and its controller into a unit module, and places the auxiliary cooling system and the main cooling system outside the module. This module unit is called a "fuel cell module unit."

[0079] like Figure 2As shown, this specific embodiment unifies the power level, overall appearance and various interfaces of the fuel cell module unit, and uniformly designs each interface into a form of quick plug or ferrule, which is convenient to connect and easy to operate, to form the fuel cell module unit provided by this specific embodiment. The fuel cell module unit includes a hydrogen inlet interface 111, a tail exhaust interface 112, a main cooling first interface 113, a main cooling second interface 114, an auxiliary cooling first interface 115, an auxiliary cooling second interface 116, and a DC / DC output interface 117.

[0080] In a specific embodiment, the hydrogen inlet port 111 is connected to the hydrogen inlet port in the system hydrogen supply circuit, and is used to absorb the hydrogen required for the fuel cell reaction;

[0081] The tail discharge interface 112 is connected to the gas-water separator in the system water recovery loop to recover the water generated by the fuel cell reaction;

[0082] The main cooling first interface 113 is connected to the high-temperature trunk road, and the main cooling second interface 114 is connected to the low-temperature trunk road; the high-temperature trunk road and the low-temperature trunk road are both connected to the primary side of the first plate heat exchanger; the first high-temperature water discharged from the main cooling first interface 113 flows through the high-temperature trunk road to the first plate heat exchanger for heat exchange, and outputs the first low-temperature water, which flows through the low-temperature trunk road and returns to the main cooling second interface 114;

[0083] The auxiliary cooling first interface 115 is connected to the auxiliary heating high-temperature trunk line, and the auxiliary cooling second interface 116 is connected to the auxiliary heating low-temperature trunk line; the auxiliary heating high-temperature trunk line and the auxiliary heating low-temperature trunk line are both connected to the primary side of the second plate heat exchanger; the second high-temperature water discharged from the auxiliary cooling first interface 115 flows through the auxiliary heating high-temperature trunk line to the second plate heat exchanger for heat exchange, and outputs the second low-temperature water, which returns to the auxiliary cooling second interface 116;

[0084] The DC / DC output interface 117 is the power output terminal of the fuel cell.

[0085] The fuel cell module unit is used to provide a place for the chemical reaction of the fuel cell. The principle is: hydrogen is absorbed through the hydrogen inlet interface 111, and the module unit itself can also absorb air (the air interface is not drawn in the attached figure, and those skilled in the art know that this interface exists to ensure that the hydrogen-oxygen reaction occurs); hydrogen and oxygen react in the module unit, and the tail exhaust interface 112 discharges air, water and a small amount of hydrogen; the DC / DC output interface 117 outputs a DC voltage to achieve reaction discharge; the fuel cell chemical reaction also generates a large amount of heat, which is exchanged through the system's main cooling circuit; the operation of the fuel cell module unit causes the device to also generate some heat, which is fully collected and utilized through the system's auxiliary heat recovery circuit.

[0086] In a specific embodiment, at least two fuel cell module units are connected to the bus through the positive and negative poles of the DC / DC output interface to achieve linear expansion of the system's power generation power; the main cooling first interfaces of at least two fuel cell module units are connected to the high-temperature main line, and the main cooling second interfaces are connected to the low-temperature main line to achieve linear expansion of the system's heat generation power.

[0087] In the overall system design, in order to achieve free expansion of power levels, several fuel cell module units are connected in parallel according to actual needs to expand the power level of the overall system. Figure 3 As shown, by connecting the positive and negative poles of the DC / DC output interfaces of several fuel cell module units to the bus, the linear expansion of the system's power generation power can be achieved; similarly, the linear expansion of the system's heat generation power is also achieved based on the parallel connection of the fuel cell module units.

[0088] In a specific embodiment, the main cooling circuit of the system includes a fuel cell module unit, a high temperature branch, a high temperature trunk, a first plate heat exchanger, a low temperature trunk and a low temperature branch connected in sequence;

[0089] The first plate heat exchanger is used to perform heat exchange on the first high-temperature water discharged from the first main cooling interface 113 of the fuel cell module unit, and output the first low-temperature water back to the second main cooling interface 114 .

[0090] Specifically, the first high-temperature water discharged from the first main cooling interface 113 of each fuel cell module unit is all collected into the high-temperature main road, and after heat exchange through the first plate heat exchanger, it is divided into various branches from the low-temperature main road and passed into the second main cooling interface 114 of each fuel cell module unit.

[0091] When the system is operating normally, the heat generated by the internal stack reaction of the fuel cell module unit is taken away through the first plate heat exchanger in the main cooling circuit of the system, providing sufficient heat source for the instant heating circuit, and returning low-temperature water to cool and dissipate the heat. The above heat exchange steps are circulated to ensure stable operation of the system.

[0092] In the main cooling circuit of the system, the high-temperature branch is provided with a first manual valve 314, and the low-temperature branch is provided with a second manual valve 313. When the module unit is installed, disassembled and repaired, the above-mentioned manual valves are used to close the water circuit at this location; the high-temperature main circuit is provided with a first temperature sensor 311 and a first pressure sensor 312, and the low-temperature main circuit is provided with a second pressure sensor 309 and a second temperature sensor 310, which are used to monitor the water temperature and water pressure in real time; the low-temperature main circuit is also provided with a first water tank 304, a first deionizer 305, a first ion concentration sensor 306, a first water pump 307, and a first filter 308. The first ion concentration sensor 306 monitors the ion concentration of the circulating water. The first water tank 304 is used for water replenishment and is connected in series with the first deionizer 305; the first water pump 307 provides power, and the first filter 308 ensures the purity of the coolant; the main cooling circuit of the system is also provided with a thermostat 302 and a heater 303, which are used to heat the circulating water when the system is started at low temperature so that the stack can quickly reach the starting temperature.

[0093] The occurrence of hydrogen-oxygen reaction requires a high temperature environment. The hydrogen fuel cell stack produces water at the cathode during the chemical reaction. When the temperature is below 0°C, if the fuel cell system is in the startup phase, as the water produced at the cathode gradually becomes saturated, ice will accumulate on the cathode side, resulting in startup failure. Cold start failure will damage the internal components of the stack and affect the chemical reaction rate. Low-temperature cold start failure of the hydrogen fuel cell system will have a significant impact on the output characteristics of the battery and reduce the battery life.

[0094] Therefore, when the fuel cell module unit is started at low temperature, this specific embodiment heats the loop cold water, that is, heats the first low-temperature water, to increase the temperature of the water flowing into the second main cold interface 114, thereby heating the fuel cell stack.

[0095] Specifically, a heating branch connecting the high-temperature main road and the low-temperature main road is set up between the high-temperature main road and the low-temperature main road close to the primary side of the first plate heat exchanger, a heater 303 is set on the heating branch, and a thermostat 302 is set at the connection point between the heating branch and the low-temperature main road.

[0096] The thermostat 302 is a three-way joint, a first joint is connected to the primary side of the first plate heat exchanger, a second joint is connected to the heating branch, and a third joint is connected to the low-temperature main road.

[0097] The first plate heat exchanger is connected in parallel with the heater, and by connecting the corresponding joint of the thermostat, it is determined whether the first high-temperature water in the high-temperature main line passes through the first plate heat exchanger or the heater.

[0098] When the second and third joints of the thermostat are connected, the first high-temperature water flow of the high-temperature main road is heated by the heater and then flows through the thermostat and the low-temperature main road into the main cooling second interface 114. At this time, the fuel cell module unit, the high-temperature main road, the heater, the thermostat, and the low-temperature main road form a hot water circulation to heat the fuel cell stack.

[0099] When the stack is heated to a certain degree, the stack is started, and the hydrogen-oxygen reaction generates heat, and no more heat is needed for the stack. At this time, the first and third connectors of the thermostat are connected to form the main cooling circuit of the system under normal operation, which takes away the heat generated by the fuel cell reaction.

[0100] In a specific embodiment, the instantaneous heat supply circuit includes a water inlet, a buffer tank, a first plate heat exchanger, a cooling tower, and a heat supply port;

[0101] The instant heating circuit includes a first instant heating circuit and a second instant heating circuit;

[0102] If the heat supply port is closed and there is no heat consumption, the water inlet is closed in this state, and the first instant heat supply loop is closed; the first instant heat supply loop includes a buffer tank, a first plate heat exchanger and a cooling tower connected in sequence; the third low-temperature water in the buffer tank is heat exchanged through the secondary side of the first plate heat exchanger, and the third high-temperature water is output to enter the cooling tower for cooling and return to the buffer tank;

[0103] If the heat supply port is open and there is heat consumption, the water inlet is open in this state, and the second instant heating circuit is open; the second instant heating circuit includes a water inlet, a buffer tank, a first plate heat exchanger, and a heat supply port connected in sequence; the water inlet is opened to replenish water to the buffer tank, and the third low-temperature water in the buffer tank is heat exchanged through the secondary side of the first plate heat exchanger, and the third high-temperature water is output and discharged from the heat supply port.

[0104] Specifically, the water source (third low temperature water) enters the buffer tank 405 from the water inlet through the third manual valve 401 and the first solenoid valve 403. The second water pump 408 provides power to make the third low temperature water enter the first plate heat exchanger and exchange heat into the third high temperature water.

[0105] If there is no hot water consumption, that is, the heating port is closed, the third high-temperature water enters the cooling tower 410 for cooling, and then opens the second solenoid valve 411 to flow back to the buffer tank 405. In this state, the water inlet is closed, and the first instant heating circuit is closed; if the user has a water demand and the heating port is opened, the third high-temperature water is directly discharged from the heating port through the third solenoid valve 404 and the fourth manual valve 402. Since the water outlet of the heating port is upstream of the cooling tower, hot water can be obtained by opening the fourth manual valve 402. At the same time, the water inlet is opened to replenish the buffer tank with water. At this time, the second instant heating circuit is open.

[0106] Among them, a liquid level meter 406 is arranged on the buffer tank 405 to feedback the water volume signal of the buffer tank and control the opening of the first solenoid valve 403 at the water inlet; a first flow meter 409 is arranged upstream of the cooling tower to monitor the amount of water flowing into the cooling tower, calculate the hot water consumption of the heating port, and then control the opening time of the first solenoid valve 403 at the water inlet; a third temperature sensor 407 is arranged on the main line of the third low-temperature water flow to monitor the secondary side inlet water temperature of the first plate heat exchanger, that is, the temperature of the third low-temperature water.

[0107] In the present invention, the main cooling circuit of the system and the instant heating circuit are connected through the first plate heat exchanger to form the main heating circuit of the system. The first plate heat exchanger is used to exchange heat between the first high-temperature water and the third low-temperature water, so that the temperature of the first high-temperature water decreases and the temperature of the third high-temperature water increases, that is, to take away the heat generated by the chemical reaction in the fuel cell module unit for heating. After the system is working, the heat supply port can provide heat not exceeding the maximum power at any time; when there is no heat utilization, the system automatically switches to the cooling tower circuit for heat dissipation, and the circuit is closed, realizing instant heating without excess water loss, effectively avoiding water resource waste.

[0108] In a specific embodiment, the auxiliary heat recovery circuit of the system includes a fuel cell module unit, an auxiliary heat high temperature branch, an auxiliary heat high temperature trunk, a second plate heat exchanger, an auxiliary heat low temperature trunk and an auxiliary heat low temperature branch connected in sequence, and a buffer tank, an auxiliary heat low temperature secondary trunk, a second plate heat exchanger, an auxiliary heat high temperature secondary trunk, and a third low temperature water flow trunk connected in sequence;

[0109] The second plate heat exchanger is used to exchange heat between the second high-temperature water and the fourth low-temperature water in the auxiliary heating low-temperature secondary trunk line, so that the temperature of the second high-temperature water decreases and the temperature of the fourth low-temperature water increases to fourth high-temperature water; the fourth high-temperature water merges into the third low-temperature water flowing through the trunk line, raising the temperature of the original third low-temperature water, and increasing the circulating water flow rate of the immediate heating circuit while keeping the temperature of the third high-temperature water unchanged.

[0110] The fuel cell system components running in the system, such as the air compressor controller, DC / DC and hydrogen circulation pump, need to dissipate heat and cool down. The water circuit is designed for cooling, and this part of the heat is collected in the instant heating circuit for recycling.

[0111] Specifically, the fuel cell module unit, auxiliary heat high temperature branch, auxiliary heat high temperature trunk, second plate heat exchanger, auxiliary heat low temperature trunk and auxiliary heat low temperature branch connected in sequence constitute the primary side of the auxiliary heat recovery loop of the system. Among them, the auxiliary heat high temperature trunk is provided with a fourth temperature sensor 501 and a third pressure sensor 502, and the auxiliary heat low temperature trunk is provided with a second water tank 503, a second deionizer 504, a second ion concentration sensor 505, a third water pump 506, a second filter 507, a fourth pressure sensor 508, and a fifth temperature sensor 509. The specific access method and function are similar to those of the main cooling loop of the above system, and will not be repeated here.

[0112] The buffer tank, auxiliary heat low-temperature secondary trunk, second plate heat exchanger, auxiliary heat high-temperature secondary trunk, and third low-temperature water flow trunk connected in sequence constitute the secondary side of the system auxiliary heat recovery loop. Among them, the buffer tank diversion port outputs the fourth low-temperature water flow through the auxiliary heat low-temperature secondary trunk, and the fourth water pump 512 provides power to make the third low-temperature water enter the second plate heat exchanger, and heat is exchanged into the fourth high-temperature water. The fourth high-temperature water flows through the auxiliary heat high-temperature secondary trunk, enters the third low-temperature water flow trunk through the confluence port, and merges into the inlet water flow.

[0113] The secondary side of the system auxiliary heat recovery loop further includes a fifth manual valve 513 , a sixth manual valve 514 , a fifth pressure sensor 511 , a sixth pressure sensor 515 , a one-way valve 516 and a fourth solenoid valve 510 .

[0114] Among them, the fourth low-temperature water has the same origin as the third low-temperature water.

[0115] The auxiliary hot water flow entering the main heating circuit at the confluence inlet increases the inlet water temperature T2 of the main heating circuit (secondary side). Without changing the outlet water temperature T1, the hot water flow at the heating outlet is increased and the auxiliary heating heat can be utilized.

[0116] Specifically, according to the heat calculation formula, Q = G·C·(t g -t h ) It can be seen that when the heating system provides the same amount of heat Q to the heat user, the supply and return water temperature difference Δt = t g -t h The circulating water volume G is proportional to the circulating water volume G. Since the auxiliary hot water is introduced into T2 of the first plate heat exchanger, the temperature of T2 is raised, so that the temperature difference between T1 and T2 becomes smaller, and the circulating water volume increases. Therefore, this specific embodiment increases the circulating water volume for heating while making full use of resources.

[0117] In a specific embodiment, the system water recovery circuit includes a fuel cell module unit, a tail exhaust branch, a gas-water separator, a tail exhaust trunk, an exhaust port, a water collection tank, a buffer tank, and a drain port;

[0118] The gas-water separator is used to separate the moisture and gas output from the tail discharge interface, discharge the gas through the exhaust port, collect the moisture in the water collecting tank, and pump it into the buffer tank; when the system has no heating and the liquid levels of the water collecting tank and the buffer tank reach the set upper limit, the moisture is discharged through the drain port.

[0119] Specifically, the tail exhaust of fuel cell air contains a large amount of water. Each fuel cell module unit connects the water to the tail exhaust branch through the tail exhaust interface, and then merges the water into the tail exhaust main road. The seventh hand valve 601 is used to control the on-off of the tail exhaust branch and the tail exhaust main road; all tail gases are separated from the water by the gas-water separator and collected in the water collecting tank 602. The water collecting tank 602 is provided with a liquid level sensor 603 for monitoring the water level. The water exceeding the set threshold can be pumped into the buffer tank through the third filter 605 and the fifth solenoid valve 606 through the fifth water pump 604. When the system has no heating and the liquid levels of the water collecting tank and the buffer tank reach the set upper limit, the sixth solenoid valve 607 and the seventh solenoid valve 608 can also be opened for direct discharge. A flame arrester 609 is also set before the exhaust port for fire prevention.

[0120] The present invention achieves the expansion of the power generation and heat generation level of the system by connecting fuel cell module units in parallel, while avoiding the complexity of system parallel connection and reducing the integration cost. The heat generated by the fuel cell system is efficiently recycled and utilized, which simplifies and optimizes the low-temperature cold start problem of the fuel cell, and realizes the uninterrupted supply of regional heat and electricity, which alleviates the greenhouse effect to a certain extent; through auxiliary heat recovery and tail water recovery, the heat and product water are maximized, the resource utilization rate is improved, and the stable operation of the cogeneration system is ensured.

[0121] Embodiment 2

[0122] Based on the above-mentioned embodiment 1, embodiment 2 of the present invention provides a fuel cell cogeneration system control method, including:

[0123] Starting the fuel cell module unit;

[0124] Collect the heat generated by the chemical reaction of the fuel cell and provide sufficient heat source for the instant heating loop through heat exchange;

[0125] Collect the heat generated by the fuel cell module unit devices and send the heat generated by the devices into the instant heating circuit;

[0126] According to whether there is heat consumption, different instantaneous heating circuits are switched to achieve flexible heating;

[0127] Collect water produced by the chemical reaction of the fuel cell module unit.

[0128] Those skilled in the art will appreciate that the units, i.e., algorithm steps, of the various examples described in conjunction with this embodiment can be implemented in electronic hardware or in a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0129] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A fuel cell cogeneration system, characterized in that: include: A fuel cell module unit, a system hydrogen supply circuit, a system main cooling circuit, a system auxiliary heat recovery circuit, an instant heating circuit, and a system water recovery circuit; the system main cooling circuit and the instant heating circuit are connected through a first plate heat exchanger to form a system heating main circuit; The fuel cell module unit provides a place for the chemical reaction of the fuel cell; the fuel cell module unit includes a hydrogen inlet interface, a tail exhaust interface, a main cooling first interface, a main cooling second interface, an auxiliary cooling first interface, an auxiliary cooling second interface, and a DC / DC output interface; the hydrogen inlet interface is connected to the hydrogen inlet in the system hydrogen supply circuit to absorb the hydrogen required for the fuel cell reaction; The tail discharge interface is connected to the gas-water separator in the system water recovery loop to recover the water generated by the fuel cell reaction; The main cooling first interface is connected to the high-temperature main road, and the main cooling second interface is connected to the low-temperature main road; the high-temperature main road and the low-temperature main road are both connected to the primary side of the first plate heat exchanger; The first high-temperature water discharged from the first main cooling interface flows through the high-temperature trunk line to the first plate heat exchanger for heat exchange, and outputs the first low-temperature water, which flows through the low-temperature trunk line back to the second main cooling interface; The auxiliary cooling first interface is connected to the auxiliary heating high-temperature trunk line, and the auxiliary cooling second interface is connected to the auxiliary heating low-temperature trunk line; The auxiliary heat high temperature trunk line and the auxiliary heat low temperature trunk line are both connected to the primary side of the second plate heat exchanger; the second high temperature water discharged from the auxiliary cooling first interface flows through the auxiliary heat high temperature trunk line to the second plate heat exchanger for heat exchange, outputs the second low temperature water, and the second low temperature water returns to the auxiliary cooling second interface; The DC / DC output interface is the power output end of the fuel cell; The system hydrogen supply circuit is used to provide the required hydrogen for the chemical reaction of the fuel cell module unit; The main cooling circuit of the system is used to collect the heat generated by the chemical reaction of the fuel cell, so as to provide sufficient heat source for the instant heating circuit through heat exchange, and to dissipate heat for the fuel cell module unit; a thermostat and a heater are also provided in the main cooling circuit of the system, which are used to heat the circulating water so that the stack can quickly reach the starting temperature when the system is started at low temperature. Specifically, a heating branch connecting the high-temperature main road and the low-temperature main road is set up between the high-temperature main road and the low-temperature main road close to the primary side of the first plate heat exchanger, a heater is set on the heating branch, and a thermostat is set at the connection point between the heating branch and the low-temperature main road; The system auxiliary heat recovery loop is used to collect the heat generated by the fuel cell module unit devices and merge the heat generated by the devices into the instant heating loop; specifically, the system auxiliary heat recovery loop includes a fuel cell module unit, an auxiliary heat high temperature branch, an auxiliary heat high temperature main road, a second plate heat exchanger, an auxiliary heat low temperature main road and an auxiliary heat low temperature branch connected in sequence, and a buffer tank, an auxiliary heat low temperature secondary road, a second plate heat exchanger, an auxiliary heat high temperature secondary road, and a third low temperature water flow through the road connected in sequence; wherein, the fuel cell module unit, the auxiliary heat high temperature branch, the auxiliary heat high temperature main road, the second plate heat exchanger, the auxiliary heat low temperature main road and the auxiliary heat low temperature branch connected in sequence constitute the primary side of the system auxiliary heat recovery loop; the buffer tank, the auxiliary heat low temperature secondary road, the second plate heat exchanger, the auxiliary heat high temperature secondary road, and the third low temperature water flow through the road connected in sequence constitute the secondary side of the system auxiliary heat recovery loop; The second plate heat exchanger is used to exchange heat between the second high-temperature water and the fourth low-temperature water in the auxiliary heating low-temperature secondary trunk line, so that the temperature of the second high-temperature water decreases and the temperature of the fourth low-temperature water increases to the fourth high-temperature water; the fourth high-temperature water flows through the auxiliary heating high-temperature secondary trunk line, enters the third low-temperature water flow trunk line through the confluence inlet, and merges into the inlet water flow, raising the temperature of the original third low-temperature water, and increasing the circulation water flow of the instant heating circuit while keeping the temperature of the third high-temperature water unchanged; The instant heating circuit is used to switch different instant heating circuits to realize flexible heating according to whether there is heating consumption; specifically, the instant heating circuit includes a water inlet, a buffer tank, a first plate heat exchanger, a cooling tower, and a heating port; The instant heating circuit includes a first instant heating circuit and a second instant heating circuit; If the heat supply port is closed and there is no heat consumption, the water inlet is closed in this state, and the first instant heat supply loop is closed; the first instant heat supply loop includes a buffer tank, a first plate heat exchanger and a cooling tower connected in sequence; the third low-temperature water in the buffer tank is heat exchanged through the secondary side of the first plate heat exchanger, and the third high-temperature water is output to enter the cooling tower for cooling and return to the buffer tank; If the heat supply port is open and there is heat consumption, the water inlet is open in this state, and the second instant heat supply loop is open; the second instant heat supply loop includes a water inlet, a buffer tank, a first plate heat exchanger, and a heat supply port connected in sequence; the water inlet is opened to replenish water to the buffer tank, and the third low-temperature water in the buffer tank is heat-exchanged through the secondary side of the first plate heat exchanger, and the third high-temperature water is output and discharged from the heat supply port; The system water recovery loop is used to collect water generated by the chemical reaction of the fuel cell module unit; the system water recovery loop includes the fuel cell module unit, the tail exhaust branch, the gas-water separator, the tail exhaust main road, the exhaust port, the water collecting tank, the buffer tank, and the drain port; The gas-water separator is used to separate the moisture and gas output from the tail discharge interface, discharge the gas through the exhaust port, collect the moisture in the water collecting tank, and pump it into the buffer tank; when the system has no heating and the liquid levels of the water collecting tank and the buffer tank reach the set upper limit, the moisture is discharged through the drain port.

2. The fuel cell cogeneration system according to claim 1, characterized in that: The hydrogen supply circuit of the system includes a hydrogen inlet, a hydrogen supply trunk line, a hydrogen supply branch line, a hydrogen discharge branch line, a tail exhaust trunk line, and an exhaust port; The hydrogen inlet delivers hydrogen to the hydrogen supply trunk, the hydrogen supply trunk is connected to the hydrogen supply branch, and the hydrogen supply branch is connected to the hydrogen inlet interface of the fuel cell module unit to provide the hydrogen required for the chemical reaction of the fuel cell; The hydrogen discharge branch is connected to the exhaust port through the tail exhaust main line, and is used to discharge the excess hydrogen that does not participate in the chemical reaction of the fuel cell and remains in the hydrogen supply circuit of the system.

3. The fuel cell cogeneration system according to claim 1, characterized in that: At least two fuel cell module units are connected to the busbar via the positive and negative electrodes of the DC / DC output interface to achieve linear expansion of the system power generation; The main cooling first interfaces of at least two fuel cell module units are connected to the high-temperature main line, and the main cooling second interfaces are connected to the low-temperature main line, so as to realize the linear expansion of the system heat generation power.

4. The fuel cell cogeneration system according to claim 1, characterized in that: The main cooling circuit of the system includes a fuel cell module unit, a high-temperature branch, a high-temperature trunk, a first plate heat exchanger, a low-temperature trunk and a low-temperature branch connected in sequence; The first plate heat exchanger is used to perform heat exchange on the first high-temperature water discharged from the main cooling first interface of the fuel cell module unit, and output the first low-temperature water back to the main cooling second interface.

5. A fuel cell cogeneration system control method, characterized in that: For the fuel cell cogeneration system according to any one of claims 1 to 4, the control method comprises: Starting the fuel cell module unit; Collect the heat generated by the chemical reaction of the fuel cell and provide sufficient heat source for the instant heating loop through heat exchange; Collect the heat generated by the fuel cell module unit devices and send the heat generated by the devices into the instant heating circuit; According to whether there is heat consumption, different instantaneous heating circuits are switched to achieve flexible heating; Collect water produced by the chemical reaction of the fuel cell module unit.

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