Heat and power cogeneration waste heat recovery system and fuel cell heat and power cogeneration system

Abstract

The utility model discloses a combined heat and power waste heat recovery system and a fuel cell combined heat and power system. The waste heat recovery system comprises a control unit, a primary side cooling loop, a three-way valve, a domestic water loop, a heating water loop and a temperature detection unit. The temperature detection unit detects the temperature of the primary side cooling loop, the domestic water loop and / or the heating water loop, and the control unit controls the three-way valve switch, the rotating speed of the domestic water pump and the rotating speed of the heating water pump according to temperature signals. After the three-way valve is closed, waste heat can be recycled, and after the three-way valve is opened, waste heat recycling is stopped, so that the heat generated by the fuel cell firstly meets the use requirement; and when the rotating speed of the control water pump is 0, namely the heat of the domestic water and the heat of the heating water are saturated, waste heat recovery is stopped. Therefore, the service life of the fuel cell can be guaranteed, and the situation that the temperature of the water tank and the heating temperature exceed the required temperature, and consequently heating equipment is out of control or performance degradation is caused is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of cogeneration, in particular to a waste heat recovery system for cogeneration and a fuel cell cogeneration system. Background Art

[0002] The waste heat recovery unit is a key unit for realizing temperature control of the fuel cell module, providing heating hot water and domestic hot water in the cogeneration system. During the commissioning process, problems such as inaccurate temperature control of the fuel cell return water or over-temperature of the heating temperature are likely to occur, which will cause the risk of performance attenuation of the fuel cell stack and out-of-control of the heating equipment.

[0003] In the prior art, the utility model of a waste heat recovery unit of a waste heat recovery system based on hydrogen cogeneration with the publication number of CN220543961U and the name of "a waste heat recovery system based on hydrogen cogeneration" discloses a cooling system and a waste heat recovery subsystem. The utility model smoothly couples the waste heat generated by the PEM fuel cell through the cooling system and the waste heat recovery subsystem, and realizes the overall collection and redistribution of waste heat to a certain extent.

[0004] The current technology couples the waste heat recovery unit through a heat exchanger with the PEM fuel cell, and there are various application scenarios. Problems such as inaccurate temperature control of the fuel cell return water or over-temperature of the heating temperature are likely to occur, which will cause the risk of performance attenuation of the fuel cell stack and out-of-control of the heating equipment. When the heating water supply and the domestic water tank are thermally saturated and there is no heat demand at the heat consumption end for the time being, the heating water pump needs to run continuously, and there is a risk of over-temperature in heating at this time, and the waste heat generated by the fuel cell cannot be consumed; when the temperature of the return water on the primary side has not reached the required temperature of the fuel cell, if heat exchange is carried out, there is a risk of large temperature difference between the inlet and outlet of the coolant of the fuel cell stack, resulting in performance attenuation of the fuel cell stack and even shutdown during the operation of the system. Summary of the Utility Model

[0005] Aiming at the above deficiencies, the technical problem to be solved by the utility model is to provide a waste heat recovery system for cogeneration and a fuel cell cogeneration system, which can not only ensure the service life of the fuel cell, but also avoid the water tank temperature and the heating temperature exceeding the required temperature, resulting in out-of-control or performance attenuation of the heating equipment.

[0006] To solve the above technical problem, the technical solution of the utility model is:

[0007] A waste heat recovery system for cogeneration includes a control unit and a primary side cooling circuit. The primary side cooling circuit includes a primary side water supply pipeline and a primary side water return pipeline. The system further includes a three-way valve, a domestic water circuit, a heating water circuit and a temperature detection unit;

[0008] The three-way valve is respectively connected to the primary side water supply pipeline, the primary side water return pipeline and the water supply main pipeline, and the three-way valve is electrically connected to the control unit;

[0009] The domestic water circuit includes a domestic water heat exchanger, a domestic water pump and a water tank. The water inlet of the domestic water heat exchanger is connected to the water supply main pipeline, and the water outlet of the domestic water heat exchanger is connected to the primary side water return pipeline;

[0010] The heating water circuit includes a heating water heat exchanger and a heating water pump. The water inlet of the heating water heat exchanger is connected to the water supply main pipeline, and the return water outlet of the heating water heat exchanger is connected to the primary side water return pipeline;

[0011] The temperature detection unit is electrically connected to the control unit. The temperature detection unit is used to detect the temperature of the primary side cooling circuit, the domestic water circuit and / or the heating water circuit, and transmit a temperature signal to the control unit. The control unit controls the three-way valve, the domestic water pump and the heating water pump according to the temperature signal.

[0012] Preferably, a domestic water valve is arranged on the domestic water circuit, and the domestic water valve is electrically connected to the control unit.

[0013] Preferably, a heating water valve is arranged on the heating water circuit, and the heating water valve is electrically connected to the control unit.

[0014] Preferably, the temperature detection unit includes a first temperature sensor arranged on the primary side water supply pipeline. The first temperature sensor is used to detect the temperature of the water in the primary side water supply pipeline; the temperature of the water in the primary side water supply pipeline, the rotation speed of the domestic water pump and the rotation speed of the heating water pump form a PID closed-loop control.

[0015] Preferably, the temperature detection unit includes a second temperature sensor arranged on the primary side water return pipeline. The second temperature sensor is used to detect the temperature of the water in the primary side water return pipeline.

[0016] Preferably, the temperature detection unit includes a third temperature sensor arranged on the water tank. The third temperature sensor is used to detect the temperature of the water in the water tank.

[0017] Preferably, the heating water circuit further includes a heating water supply pipeline and a heating water return pipeline. The heating water supply pipeline is connected to the water outlet of the heating water heat exchanger, and the heating water return pipeline passes through the heating water pump and is connected to the water return inlet of the heating water heat exchanger.

[0018] Preferably, the temperature detection unit includes a fourth temperature sensor provided in the heating supply water pipeline, and the fourth temperature sensor is used to detect the temperature of the water in the heating supply water pipeline.

[0019] Preferably, the temperature detection unit includes a fifth temperature sensor provided in the heating return water pipeline, and the fifth temperature sensor is used to detect the temperature of the water in the heating return water pipeline.

[0020] A fuel cell combined heat and power system includes a fuel cell module and a radiator, and further includes the above-mentioned waste heat recovery system. The primary side cooling circuit of the waste heat recovery system is used to cool the fuel cell module.

[0021] After adopting the above technical solution, the beneficial effects of the present invention are:

[0022] Due to the waste heat recovery system for combined heat and power of the present invention and the fuel cell combined heat and power system, the waste heat recovery system includes a control unit, a primary side cooling circuit, a three-way valve, a domestic water circuit, a heating water circuit and a temperature detection unit. The temperature detection unit, the three-way valve, the domestic water pump and the heating water pump are respectively electrically connected to the control unit; the three-way valve is provided between the water supply and the water return of the primary side cooling circuit, and the temperature detection unit is used to detect the temperature of the primary side cooling circuit, the domestic water circuit and / or the heating water circuit, and transmit the temperature signal to the control unit. The control unit controls the opening and closing of the three-way valve, the rotation speed of the domestic water pump and the rotation speed of the heating water pump according to the temperature signal. When the three-way valve is closed, the primary side cooling circuit can supply water to the domestic water circuit and the heating water circuit, that is, waste heat recovery is carried out. When the three-way valve is opened, the primary side cooling circuit stops supplying water to the domestic water circuit and the heating water circuit, so that the heat generated by the fuel cell itself cannot meet its own use requirements first; at the same time, when the rotation speeds of the domestic water pump and the heating water pump are controlled to be 0, waste heat recovery is not carried out, and waste heat recovery can be stopped when the heat of domestic water and heating water reaches saturation, so as to avoid the water tank temperature and the heating temperature exceeding the required temperature, resulting in the out-of-control of the heating equipment or the performance attenuation. It can be seen that the present invention can not only ensure the service life of the fuel cell, but also avoid the water tank temperature and the heating temperature exceeding the required temperature, resulting in the out-of-control of the heating equipment or the performance attenuation. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the waste heat recovery system in the present invention;

[0024] In the figure: 1 - primary side cooling circuit, 10 - primary side water supply pipeline, 11 - primary side water return pipeline, 2 - domestic water circuit, 20 - domestic water heat exchanger, 21 - domestic water pump, 22 - water tank, 23 - domestic water valve, 24 - domestic water supply pipeline, 3 - heating water circuit, 30 - heating water heat exchanger, 31 - heating water pump, 32 - heating water valve, 33 - heating water supply pipeline, 34 - heating water return pipeline, 4 - three-way valve, 5 - radiator, 6 - water supply main pipe, 70 - first temperature sensor, 71 - second temperature sensor, 72 - third temperature sensor, 73 - fourth temperature sensor, 74 - fifth temperature sensor. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0026] It should be noted that in the description of the present utility model, the terms indicating directions or positional relationships such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present utility model.

[0027] In addition, it should also be noted that in the description of the present utility model, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0028] Embodiment 1:

[0029] As Figure 1 shown, a waste heat recovery system for combined heat and power includes a control unit and a primary side cooling circuit 1. The primary side cooling circuit 1 includes a primary side water supply pipeline 10 and a primary side water return pipeline 11. The waste heat recovery system further includes a three-way valve 4, a domestic water circuit 2, a heating water circuit 3, and a temperature detection unit. The control unit can be, but is not limited to, a single-chip microcomputer.

[0030] The three-way valve 4 is respectively connected to the primary side water supply pipeline 10, the primary side water return pipeline 11 and the water supply main pipeline 6. The three-way valve 4 is electrically connected to the control unit, and the three-way valve 4 is controlled to open and close by the control unit. When it connects the primary side water supply pipeline 10 and the primary side water return pipeline 11 and disconnects the primary side water supply pipeline 10 and the water supply main pipeline 6, the waste heat recovery is stopped. When it connects the primary side water supply pipeline 10 and the water supply main pipeline 6 and disconnects the primary side water supply pipeline 10 and the primary side water return pipeline 11, the waste heat recovery can be carried out.

[0031] The domestic water circuit 2 includes a domestic water heat exchanger 20, a domestic water pump 21 and a water tank 22. The water inlet of the domestic water heat exchanger 20 is connected to the water supply main pipeline 6, the water outlet of the domestic water heat exchanger 20 is connected to the primary side water return pipeline 11, and a domestic water supply pipeline 24 is also arranged on the water tank 22, and users draw water from the domestic water supply pipeline 24; in this embodiment, a domestic water valve 23 is arranged on the domestic water circuit 2. The domestic water pump 21 and the domestic water valve 23 are respectively electrically connected to the control unit. The opening degree of the domestic water valve 23 is controlled by the control unit to adjust the water flow rate in the domestic water circuit 2, and further adjust the waste heat recovery capacity on the domestic water side. The rotation speed of the domestic water pump 21 is controlled by the control unit, and the speed is controlled to adjust the speed of the domestic water circulation to adjust the waste heat recovery capacity of the domestic water.

[0032] The heating water circuit 3 includes a heating water heat exchanger 30 and a heating water pump 31. The water inlet of the heating water heat exchanger 30 is connected to the water supply main pipeline 6, and the return water outlet of the heating water heat exchanger 30 is connected to the primary side water return pipeline 11; in this embodiment, a heating water valve 32 is arranged on the heating water circuit 3. The heating water valve 32 is electrically connected to the control unit. The heating water circuit 3 further includes a heating water supply pipeline 33 and a heating water return pipeline 34. The heating water supply pipeline 33 is connected to the water outlet of the heating water heat exchanger 30, and the heating water return pipeline 34 passes through the heating water pump 31 and is connected to the water return inlet of the heating water heat exchanger 30. The opening degree of the heating water valve 32 is controlled by the control unit to adjust the water flow rate in the heating water circuit 3, and further adjust the waste heat recovery capacity on the heating water side. The rotation speed of the heating water pump 31 is controlled by the control unit, and the speed is controlled to adjust the speed of the heating water circulation to adjust the waste heat recovery capacity of the heating water.

[0033] The temperature detection unit is electrically connected to the control unit. The temperature detection unit is used to detect the temperature of the primary side cooling circuit 1, the domestic water circuit 2 and / or the heating water circuit 3, and transmit the temperature signal to the control unit. The control unit controls the three-way valve 4, the domestic water pump 21 and the heating water pump 31 according to the temperature signal.

[0034] Such as Figure 1As shown in the figure, when the utility model is actually in use, after the control unit receives the start signal of the waste heat recovery unit, the control unit controls the three-way valve 4, the heating water valve 32 and the domestic water valve 23 to open according to a certain ratio according to the actual demand.

[0035] When the three-way valve 4 disconnects the primary side return water pipe 11 and the primary side water supply pipe 10, the primary side cooling circuit 1 can supply water to the domestic water circuit 2 and the heating water circuit 3, that is, waste heat recovery and utilization are carried out. When the three-way valve 4 connects the primary side return water pipe 11 and the primary side water supply pipe 10, the primary side cooling circuit 1 stops supplying water to the domestic water circuit 2 and the heating water circuit 3, so that the heat generated by the fuel cell itself first meets its own use requirements. At the same time, when the rotational speeds of the domestic water pump 21 and the heating water pump 31 are set to 0, waste heat recovery is not carried out. When the heat of domestic water and heating water reaches saturation, waste heat recovery can be stopped, thereby preventing the temperature of the water tank 22 and the heating temperature from exceeding the required temperature, causing the heating equipment to get out of control or performance degradation. It can be seen that the utility model can not only ensure the service life of the fuel cell, but also prevent the temperature of the water tank 22 and the heating temperature from exceeding the required temperature, causing the heating equipment to get out of control or performance degradation.

[0036] As Figure 1 shown, the temperature detection unit of the utility model includes a first temperature sensor 70 provided on the primary side water supply pipe 10, and the first temperature sensor 70 is used to detect the temperature T1 of the water in the primary side water supply pipe 10.

[0037] If T1 is less than the required temperature at the fuel cell inlet, it means that the heat generated by the fuel cell itself cannot meet its own use requirements at this time, and the waste heat recovery unit does not need to exchange heat. The control unit sets the rotational speeds of the domestic water pump 21 and the heating water pump 31 to 0. It should be noted that the utility model can use a voltage comparison circuit to compare the magnitudes of the temperature T1 and the required temperature at the fuel cell inlet. In fact, it is to compare the magnitudes of voltages. The required temperature at the fuel cell inlet can be the reference voltage built in the voltage comparison circuit, and the temperature T1 is the voltage input to the voltage comparison circuit. Different voltages are output according to the comparison results, such as high level and low level. The following temperature comparisons can all adopt this method and will not be repeated.

[0038] As Figure 1 shown, in this embodiment, the temperature T1 of the water in the primary side water supply pipe 10, the rotational speed of the domestic water pump 21 and the rotational speed of the heating water pump 31 form a PID closed-loop control. Specifically, if T1 is greater than or equal to the required temperature at the fuel cell inlet, it means that the heat generated by the fuel cell itself has met its own use requirements, and there is still excess heat that can be exchanged through the plate heat exchanger. At this time, the heating water pump 31 and the domestic water pump 21 adjust their rotational speeds through PID, and the adjustment target is that T1 is equal to the required temperature at the fuel cell inlet.

[0039] As Figure 1 shown, in the present utility model, the temperature detection unit includes a second temperature sensor 71 provided on the primary side return water pipeline 11. The second temperature sensor 71 is used to detect the temperature T2 of the water in the primary side return water pipeline 11.

[0040] When the waste heat recovery unit of the fuel cell combined heat and power supply system is started, by detecting the primary side return water temperature T2, it can be known whether there is waste heat available for heat exchange in the plate heat exchanger. The plate heat exchanger refers to the heat exchange between the heating water heat exchanger 30 and the domestic water heat exchanger 20, avoiding the direct heat exchange resulting in too low primary side return water temperature, which may cause the fuel cell to limit power or stop suddenly due to the large temperature difference between the coolant inlet and outlet, and significantly improving the service life of the fuel cell.

[0041] As Figure 1 shown, in the present utility model, the temperature detection unit includes a third temperature sensor 72 provided on the water tank 22. The third temperature sensor 72 is used to detect the temperature T3 of the water in the water tank 22.

[0042] The temperature detection unit includes a fifth temperature sensor 74 provided on the heating return water pipeline 34. The fifth temperature sensor 74 is used to detect the temperature T5 of the water in the heating return water pipeline 34.

[0043] If T3 is the domestic water demand temperature or T5 is the heating demand temperature, at this time, the water tank 22 or the heating water circuit 3 has reached thermal saturation, and the domestic water valve 23 or the heating water valve 32 that has reached thermal saturation is closed; if both T3 is the domestic water demand temperature and T5 is the heating demand temperature are satisfied simultaneously, it means that both the water tank 22 and the heating water circuit 3 have reached thermal saturation. At this time, the three-way valve 4 is controlled to make the primary side supply water directly return through the primary side return water pipeline 11, and the waste heat that cannot be consumed at this time is directly dissipated by the radiator 5.

[0044] If T3 is less than the domestic water demand temperature or T5 is less than the heating demand temperature, it means that the heat-using end is using the heat source. At this time, the radiator 5 is disabled, and the three-way valve 4, the domestic water valve 23, and the heating water valve 32 are controlled to open and close according to the demand.

[0045] As Figure 1 shown, in the present utility model, the temperature detection unit includes a fourth temperature sensor 73 provided on the heating supply water pipeline 33. The fourth temperature sensor 73 is used to detect the temperature T4 of the water in the heating supply water pipeline 33. By detecting the temperature T4 of the water in the heating supply water pipeline 33, it can be known to what extent the water in the heating water circuit 3 is heated by using waste heat recovery.

[0046] In summary, for the waste heat recovery system of cogeneration of the present utility model, after the control unit receives the start signal, it controls the domestic water pump 21, the domestic water valve 23, the heating water pump 31, the heating water valve 32 and the three-way valve 4 according to the detected primary side supply water temperature T1, the primary side return water temperature T2, the water tank 22 temperature T3, the heating supply water temperature T4 and the heating return water temperature T5, so as to achieve precise regulation of the primary side return water, the domestic water temperature and the heating water; avoid the problem that the fuel cell module is power-limited or suddenly stopped due to too low primary side return water temperature; at the same time, the heating temperature and the domestic water temperature are adjusted according to the demand, effectively avoiding the problem of over-temperature.

[0047] Embodiment 2:

[0048] A fuel cell cogeneration system includes a fuel cell module and a radiator 5, and further includes the waste heat recovery system described in Embodiment 1. The primary side cooling circuit 1 of the waste heat recovery system is used to cool the fuel cell module.

[0049] For the fuel cell cogeneration system of the present utility model, by adopting the waste heat recovery system of Embodiment 1, precise regulation of the primary side return water, the domestic water temperature and the heating water is achieved; the problem that the fuel cell module is power-limited or suddenly stopped due to too low primary side return water temperature is avoided; at the same time, the heating temperature and the domestic water temperature are adjusted according to the demand, effectively avoiding the problem of over-temperature, and at the same time realizing the recovery and reuse of waste heat, achieving energy conservation and reducing energy consumption.

[0050] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A waste heat recovery system for combined heat and power generation, comprising a control unit and a primary cooling circuit, wherein the primary cooling circuit comprises a primary water supply pipeline and a primary water return pipeline, characterized in that: The system also includes a three-way valve, a domestic water circuit, a heating water circuit and a temperature detection unit; The three-way valve is respectively connected to the primary water supply pipeline, the primary water return pipeline and the water supply main, and the three-way valve is electrically connected to the control unit; The domestic water circuit includes a domestic water heat exchanger, a domestic water pump and a water tank, the water inlet of the domestic water heat exchanger is connected to the water supply main, and the water outlet of the domestic water heat exchanger is connected to the primary side return water pipeline; The heating water circuit includes a heating water heat exchanger and a heating water pump, the water inlet of the heating water heat exchanger is connected to the water supply main, and the return water outlet of the heating water heat exchanger is connected to the primary side return water pipeline; The temperature detection unit is electrically connected to the control unit, and is used to detect the temperature of the primary side cooling circuit, the domestic water circuit and / or the heating water circuit, and transmit the temperature signal to the control unit. The control unit controls the three-way valve, the domestic water pump and the heating water pump according to the temperature signal.

2. The waste heat recovery system for combined heat and power generation according to claim 1, characterized in that: The domestic water circuit is provided with a domestic water valve, and the domestic water valve is electrically connected to the control unit.

3. The waste heat recovery system for combined heat and power generation according to claim 1, characterized in that: The heating water loop is provided with a heating water valve, and the heating water valve is electrically connected to the control unit.

4. The waste heat recovery system for combined heat and power generation according to claim 1, characterized in that: The temperature detection unit comprises a first temperature sensor disposed on the primary water supply pipeline, the first temperature sensor being used to detect the temperature of water in the primary water supply pipeline; The temperature of the water in the primary water supply pipeline, the rotation speed of the domestic water pump and the rotation speed of the heating water pump constitute a PID closed-loop control.

5. The waste heat recovery system for combined heat and power generation according to claim 1, characterized in that: The temperature detection unit includes a second temperature sensor disposed on the primary-side return water pipeline, and the second temperature sensor is used to detect the temperature of water in the primary-side return water pipeline.

6. The waste heat recovery system for combined heat and power generation according to claim 1, characterized in that: The temperature detection unit includes a third temperature sensor disposed on the water tank, and the third temperature sensor is used to detect the temperature of water in the water tank.

7. The waste heat recovery system for combined heat and power generation according to claim 1, characterized in that: The heating water circuit also includes a heating water supply pipeline and a heating water return pipeline. The heating water supply pipeline is connected to the water outlet of the heating water heat exchanger, and the heating water return pipeline is connected to the return water inlet of the heating water heat exchanger through the heating water pump.

8. The waste heat recovery system for combined heat and power generation according to claim 7, characterized in that: The temperature detection unit includes a fourth temperature sensor disposed in the heating and water supply pipeline, and the fourth temperature sensor is used to detect the temperature of water in the heating and water supply pipeline.

9. The waste heat recovery system for combined heat and power generation according to claim 7, characterized in that: The temperature detection unit includes a fifth temperature sensor arranged in the heating return water pipeline, and the fifth temperature sensor is used to detect the temperature of water in the heating return water pipeline.

10. A fuel cell cogeneration system, comprising a fuel cell module and a radiator, characterized in that: It also includes the waste heat recovery system according to any one of claims 1 to 9, wherein the primary side cooling circuit of the waste heat recovery system is used to cool the fuel cell module.

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