Steam boiler flue gas waste heat recovery system combined with heat pump operation

Abstract

The utility model provides a steam boiler flue gas waste heat recovery system combined with heat pump operation, which is used for a steam boiler and comprises a flue gas heat exchanger and a heat pump, the flue gas heat exchanger is configured on a flue gas pipeline of the steam boiler; an output pipeline and an input pipeline are arranged between the flue gas heat exchanger and the heat pump, so that outside inlet water is cooled by the heat pump, then conveyed to the flue gas heat exchanger through the output pipeline for flue gas waste heat recovery, returned to the heat pump through the input pipeline, heated and then output to a steam boiler. Through cooperation of the flue gas heat exchanger and the heat pump which are connected through the configured pipeline, the water temperature is reduced through the heat pump evaporator, meanwhile, the water temperature is increased through the heat pump condenser, finally, the water outlet temperature is effectively increased, and full utilization of heat energy is achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to steam boiler equipment technical field, specifically, relate to a steam boiler flue gas waste heat recovery system of combined heat pump operation. BACKGROUND

[0002] In the steam boiler operation process, using the flue gas waste heat recovery system, the flue gas waste heat is deeply recovered and utilized, which can not only turn waste into treasure and reduce the natural gas consumption, but also reduce the carbon dioxide emission.

[0003] At present, the flue gas waste heat recovery system commonly used in steam boilers is a flue gas heat exchanger, which recovers the heat in the flue gas by using the steam boiler inlet water and flue gas heat exchange.

[0004] However, due to the small flow of steam boiler inlet water, the temperature of the inlet water rises quickly during heat exchange, that is, the heat that can be absorbed is very limited, so that the flue gas waste heat cannot be fully recovered, resulting in low flue gas waste heat recovery efficiency. SUMMARY

[0005] The problem solved by the utility model is how to improve the flue gas waste heat recovery efficiency of the steam boiler.

[0006] To solve the above problems, the utility model provides a steam boiler flue gas waste heat recovery system of combined heat pump operation, which is used for steam boiler, and comprises:

[0007] A flue gas heat exchanger and a heat pump;

[0008] The flue gas heat exchanger is arranged on the flue gas pipeline of the steam boiler;

[0009] Input and output pipelines are arranged between the flue gas heat exchanger and the heat pump, so that the inlet water from the outside is cooled by the heat pump, then transported to the flue gas heat exchanger through the output pipeline for flue gas waste heat recovery, and the inlet water after waste heat recovery is returned to the heat pump through the input pipeline for temperature rise and then output to the steam boiler.

[0010] Optionally, the steam boiler flue gas waste heat recovery system of combined heat pump operation provided by the utility model is provided with an inlet water pipeline and an outlet water pipeline on the heat pump, the inlet water pipeline is used for inputting the inlet water from the outside to the heat pump, and the outlet water pipeline is used for outputting the inlet water after temperature rise by the heat pump;

[0011] The inlet water pipeline and the output pipeline are connected through a first pipeline, and the outlet water pipeline and the input pipeline are connected through a second pipeline.

[0012] Optionally, the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the present application further comprises a control valve assembly.

[0013] The control valve assembly comprises a first water inlet control valve and a first water outlet control valve.

[0014] The water inlet control valve is arranged on the first pipeline, and the first water outlet control valve is arranged on the second pipeline.

[0015] Optionally, the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the present application further comprises a second water inlet control valve and a second water outlet control valve.

[0016] The second water inlet control valve is arranged on the output pipeline close to the heat pump end, and the second water outlet control valve is arranged on the water outlet pipeline close to the heat pump.

[0017] Optionally, each control valve in the control valve assembly of the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the present application is an electrically operated on-off valve.

[0018] Optionally, the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the present application further comprises a controller, which is electrically connected with each control valve in the control valve assembly.

[0019] Optionally, the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the present application further comprises at least one temperature sensor.

[0020] The temperature sensors are respectively arranged at both ends of the output pipeline, both ends of the input pipeline, the water inlet pipeline and the water outlet pipeline.

[0021] The temperature sensors and the heat meter are respectively electrically connected with the controller.

[0022] Optionally, the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the present application further comprises a heat meter, which is arranged on the water outlet pipeline and electrically connected with the controller.

[0023] Optionally, the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the present application further comprises an electric meter, which is electrically connected with the controller.

[0024] Optionally, the steam boiler flue gas waste heat recovery system combined with heat pump operation provided in the application, the controller is PLC, and each control valve in the control valve assembly is an electrically-operated on-off valve.

[0025] The steam boiler flue gas waste heat recovery system combined with heat pump operation provided in the application, by configuring a flue gas heat exchanger on the flue gas pipeline of the steam boiler, and configuring a heat pump connected with the flue gas heat exchanger through an output pipeline and an input pipeline, so that the water from outside is cooled by the heat pump, then transported to the flue gas heat exchanger through the output pipeline for flue gas waste heat recovery, and returned to the heat pump through the input pipeline for heating and then output to the steam boiler, thereby reducing the initial temperature of the water entering the flue gas heat exchanger, increasing the heating space of the water, and improving the flue gas heat recovery efficiency in the flue gas heat exchanger; and the water after completing the flue gas waste heat recovery is returned to the heat pump through the input pipeline, and the heat extracted by reducing the initial temperature is used to further heat the water, that is, the water temperature is reduced by the heat pump evaporator, and the water temperature is increased by the heat pump condenser, so that the water temperature is effectively increased, and the heat energy is fully utilized. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 Structure diagram of the steam boiler flue gas waste heat recovery system combined with heat pump operation of the related art steam boiler;

[0028] Figure 2 Structure diagram of the steam boiler flue gas waste heat recovery system combined with heat pump operation of the steam boiler of some embodiments of the application;

[0029] Figure 3 Variation diagram of heat content per degree of temperature difference of natural gas flue gas at different temperatures;

[0030] Figure 4 Structure diagram of the steam boiler flue gas waste heat recovery system combined with heat pump operation of the steam boiler of some embodiments of the application;

[0031] Figure 5 Variation structure diagram of the water temperature of the steam boiler flue gas waste heat recovery system combined with heat pump operation of the related art steam boiler;

[0032] Figure 6The water inlet temperature change structure diagram of the steam boiler flue gas waste heat recovery system of the steam boiler combined with the heat pump operation of the embodiment of the application.

[0033] Explanation of reference signs:

[0034] 1 - output pipeline; 2 - input pipeline; 3 - first pipeline; 4 - second pipeline; 5 - first water inlet control valve; 6 - first water outlet control valve; 7 - second water inlet control valve; 8 - second water outlet control valve. DETAILED DESCRIPTION

[0035] The utility model will be further explained in detail below by combining with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related utility model, and are not limited to the utility model. In addition, it should be noted that only the parts related to the utility model are shown in the drawings for convenience of description.

[0036] It should be noted that the embodiments in the utility model and the features in the embodiments can be combined with each other without conflict. The utility model will be described in detail below by combining with the drawings and embodiments.

[0037] It can be understood that for the gas steam boiler, as shown in Figure 1 and Figure 2 , it includes a combustion machine, a gas steam boiler and a flue gas pipeline.

[0038] The combustion machine supplies heat to the gas steam boiler to heat the water therein. At the same time, the generated flue gas is discharged through the flue gas pipeline.

[0039] In practice, according to the composition and characteristics of the flue gas of the gas boiler, a large amount of water vapor is contained in the flue gas of the gas boiler, and the dew point temperature of the flue gas is generally about 57℃. When the flue gas temperature drops below the dew point temperature, the water vapor in the flue gas condenses into liquid water, and a large amount of heat is released in the phase change process, i.e. condensation heat (latent heat), which is much more than the sensible heat of the flue gas.

[0040] The latent heat of vaporization of water vapor in the flue gas is about 10% of the low heat value of natural gas (the latent heat of vaporization of water vapor in 1t of flue gas of the steam boiler is more than 6.5x10 4 Kcal), and the recovery of this part of heat can raise the water inlet of 1t boiler by more than 65℃.

[0041] Since the dew point temperature of water in the flue gas is about 57℃, the latent heat of vaporization of this part of water vapor can raise the water inlet temperature of the boiler to 57℃ at most, i.e. from room temperature to about 57℃, so the flue gas waste heat cannot be completely recovered, and a large amount of flue gas waste heat is still discharged into the atmosphere.

[0042] For example, as shown in Figure 1As shown, in the related art, the flue gas waste heat recovery system of the steam boiler recovers the heat in the flue gas by using the steam boiler inlet water to exchange heat with the flue gas.

[0043] In Figure 1 As shown in the system, the flue gas waste heat is recovered by using the steam boiler inlet water, and the flow is small. For example, about 1t of inlet water is used for heat exchange for every 1t of steam produced. This cannot fully exchange heat and cannot fully recover the flue gas waste heat.

[0044] Moreover, due to the small flow, the temperature rise in the heat exchange process is fast, that is, the temperature of the steam boiler inlet water is high.

[0045] Therefore, in the present application, in order to improve the flue gas waste heat recovery efficiency, more flue gas waste heat is recovered by reducing the water temperature entering the flue gas heat exchanger.

[0046] For example, as shown in Figure 5 and Figure 6 As shown, the steam boiler inlet water recovers the flue gas waste heat, and the same flue gas amount and water flow, the flue gas temperature of 120℃, the inlet water of 40℃ can be raised to about 72℃, the inlet water of 30℃ can also be raised to about 72℃, and the inlet water of 20℃ can also be raised to about 72℃, but the lower the water temperature, the more flue gas waste heat is recovered. The flue gas waste heat recovered per ton of water in the above three cases is 3.2x10 4 Kcal, 4.2x10 4 Kcal and 5.2x10 4 Kcal respectively. That is, for every 10℃ reduction in the inlet water temperature, 1x10 4 Kcal of flue gas heat can be recovered per ton of water.

[0047] That is, it can be understood that the flue gas waste heat recovery amount is closely related to the inlet water temperature. Moreover, the lower the inlet water temperature, the more flue gas waste heat is recovered. Therefore, if the inlet water temperature can be reduced, more flue gas waste heat can be recovered.

[0048] Therefore, the steam boiler flue gas waste heat recovery system provided by the present application, which is combined with the steam boiler and the heat pump, reduces the inlet water temperature by cooperating the heat pump and the electromagnetic valve, so that the water temperature entering the flue gas heat exchanger is kept as low as possible, thereby a large amount of waste heat can be absorbed when the flue gas waste heat is recovered after entering the flue gas heat exchanger, that is, the initial temperature of the steam boiler inlet water is greatly reduced by the present application to improve the flue gas waste heat recovery rate.

[0049] In order to better understand the steam boiler flue gas waste heat recovery system combined with the steam boiler and the heat pump provided by the present application, the following will be described in detail. Figure 2

[0050] Figure 2 ​The figure shows the structure diagram of the combined heat pump operated steam boiler flue gas waste heat recovery system of some embodiments of the present application, which is used for a gas steam boiler, such as Figure 2 As shown, the combined heat pump operated steam boiler flue gas waste heat recovery system can include:

[0051] Flue gas heat exchanger and heat pump.

[0052] The flue gas heat exchanger is configured on the flue gas pipeline of the steam boiler.

[0053] The output pipeline 1 and the input pipeline 2 are arranged between the flue gas heat exchanger and the heat pump, so that the water from outside is cooled by the heat pump, then transported to the flue gas heat exchanger through the output pipeline 1 for flue gas waste heat recovery, and the water after waste heat recovery is returned to the heat pump through the input pipeline 2 for heating and then output to the steam boiler.

[0054] Specifically, for a gas steam boiler, such as Figure 1 and Figure 2 As shown, it includes a combustion machine, a gas steam boiler and a flue gas pipeline.

[0055] Correspondingly, in order to improve the recovery efficiency of flue gas waste heat, the present application configures a flue gas heat exchanger which can be installed on the flue gas pipeline, and a heat pump which can be communicated with the flue gas heat exchanger through pipelines, i.e. output pipeline 1 and input pipeline 2, to form a combined heat pump operated steam boiler flue gas waste heat recovery system.

[0056] Among them, the heat pump can cool the water from outside, i.e. reduce the initial temperature of the water, and transport it to the flue gas heat exchanger through the output pipeline 1; and then return through the input pipeline 2 after completing heat exchange, so as to further heat the water by extracting the heat when reducing the initial temperature.

[0057] The flue gas heat exchanger can be used to heat exchange the cooled water with flue gas to realize flue gas waste heat recovery.

[0058] For example, in actual use, the water for recovering flue gas waste heat, i.e. the water from outside, is first cooled in the evaporation side of the heat pump, which can be cooled by more than 10℃.

[0059] Further, the water cooled by the heat pump is recovered by the flue gas heat exchanger to recover more flue gas waste heat.

[0060] Finally, the water after completing flue gas waste heat recovery is returned to the condensation side of the heat pump through the input pipeline 2, and the heat pump will continue to use the heat extracted when reducing the initial temperature, such as the heat extracted by 10℃ temperature difference, to heat the water in the condensation side, so as to realize effective and sufficient use of energy.

[0061] That is, in the embodiments of the present application, the flue gas heat exchanger is arranged on the flue gas pipeline of the steam boiler, and the heat pump connected with the flue gas heat exchanger through the output pipeline and the input pipeline, so that the water from outside is cooled by the heat pump, then transported to the flue gas heat exchanger through the output pipeline for flue gas waste heat recovery, and then returned to the heat pump through the input pipeline for heating and output to the steam boiler, thereby reducing the initial temperature of the water entering the flue gas heat exchanger, increasing the heating space of the water, improving the flue gas heat recovery efficiency in the flue gas heat exchanger, and returning the water after completing the flue gas waste heat recovery to the heat pump through the input pipeline, using the heat extracted by reducing the initial temperature to further heat the water, that is, reducing the water temperature through the heat pump evaporator and increasing the water temperature through the heat pump condenser, thereby effectively increasing the outlet water temperature and realizing full utilization of heat energy.

[0062] Optionally, in some embodiments of the present application, in order to reduce the heat pump energy consumption and improve the water supply speed, the water can be divided into two parts when entering the heat pump.

[0063] That is, as shown in Figure 3 , the heat pump is provided with a water inlet pipeline and a water outlet pipeline, the water inlet pipeline is used for inputting the water from outside to the heat pump, and the water outlet pipeline is used for outputting the water heated by the heat pump;

[0064] And the water inlet pipeline and the output pipeline are communicated through the first pipeline 3, and the water outlet pipeline and the input pipeline are communicated through the second pipeline 4.

[0065] Specifically, in actual use, part of the water entering from the water inlet pipeline can be directly transported to the flue gas heat exchanger through the first pipeline 3 and the output pipeline 1, and the other part can be transported to the heat pump for cooling, and then transported to the flue gas heat exchanger for cooling through the output pipeline after cooling.

[0066] Correspondingly, the water in the flue gas heat exchanger after completing heat recovery, when passing through the input pipeline, part of it can return to the heat pump through the second pipeline 4 to further heat the heat extracted by cooling, and the other part can be directly transported to the steam boiler through the input pipeline 2 and the second pipeline 4.

[0067] Optionally, as shown in Figure 3 , in some embodiments of the present application, in the above structure, in order to improve the heat recovery efficiency, control valves can be arranged on the first pipeline 3 and the second pipeline 4.

[0068] The steam boiler flue gas waste heat recovery system operating in combination with the heat pump further comprises a control valve assembly, which comprises a first water inlet control valve 5 and a first water outlet control valve; the water inlet control valve is arranged on the first pipeline 3, and the first water outlet control valve 6 is arranged on the second pipeline 4.

[0069] Specifically, as shown in the figure, when it is required to directly improve the waste heat recovery efficiency, for example, the current electricity price is low, the first water inlet control valve 5 and the first water outlet control valve 6 can be closed, so that the water cannot directly reach the flue gas heat exchanger but is completely transported to the heat pump, and after the waste heat recovery of the flue gas is completed in the flue gas heat exchanger, the water is all re-transported to the heat pump for heating again. Figure 3

[0070] Further, as shown in the figure, in some embodiments, in order to improve the control efficiency, a set of control valves, i.e., a control valve assembly, can be further arranged in the steam boiler flue gas waste heat recovery system operating in combination with the heat pump, which comprises a second water inlet control valve 7 and a second water outlet control valve 8. Figure 3

[0071] Specifically, as shown in the figure, in some cases, when it is required to utilize the heat pump to improve the waste heat recovery efficiency, the first water inlet control valve 5 and the first water outlet control valve 6 can be closed, and the second water inlet control valve 7 and the second water outlet control valve 8 can be opened, so that the external water supplement can be transported to the heat pump for cooling, and then transported to the flue gas heat exchanger to complete the waste heat recovery of the flue gas and then transported to the heat pump for heating again.

[0072] Figure 3

[0073] It can be understood that, since the market electricity price generally adopts the peak-valley flat electricity price system, the heat production cost is calculated by the electricity price and the COP of the heat pump, and therefore, if the heat production cost of the heat pump is higher than the gas heat production cost in the period when the electricity price is high, the heat pump can not be operated in this period.

[0074] That is, in another case, the first water inlet control valve 5 and the first water outlet control valve 6 are opened, and the second water inlet control valve 7 and the second water outlet control valve 8 are closed, so that the heat exchange is only performed by the flue gas heat exchanger in the whole system.

[0075] In the control valve assembly in the embodiment of the present application, each control valve can be an electrically operated on-off valve, which can be selected flexibly according to the actual situation, and the present application does not limit this.

[0076] Optionally, as shown in the figure, the control valve assembly in the steam boiler flue gas waste heat recovery system operating in combination with the heat pump can further comprise a water temperature sensor 9. Figure 4 ​​​​As shown in some embodiments of this application, in order to improve the intelligence level of the system, the combined heat pump operating steam boiler flue gas waste heat recovery system may also be equipped with a control box, which contains a controller that is electrically connected to each control valve in the control valve assembly.

[0077] The controller can be a PLC or an embedded system, etc., and this application does not impose any restrictions on it.

[0078] This controller is used to send control commands to each control valve to efficiently control the opening and closing of each control valve.

[0079] Furthermore, such as Figure 4 As shown, the combined heat pump operating steam boiler flue gas waste heat recovery system is also equipped with a temperature sensor, an electricity meter, and a heat meter. The temperature sensor, electricity meter, and heat meter are electrically connected to the controller to monitor flue gas temperature, water temperature, heat, electricity, thermal power, electrical power, flow rate, etc., and transmit the monitored data to the controller.

[0080] like Figure 4 As shown, in some embodiments, multiple temperature sensors can be arranged on the inlet pipe, input pipe, outlet pipe, and output pipe to monitor the water flow temperature at the inlet location, the inlet and outlet locations of the heat pump, and the inlet and outlet locations of the flue gas heat exchanger.

[0081] The heat meter can be installed on the outlet side of the heat pump and the inlet side of the steam boiler to monitor the heat of the water flow at the corresponding locations.

[0082] The meter can be installed at the corresponding locations of the water pump and heat pump in the water inlet pipe to monitor the power consumption of the pumps.

[0083] In practice, the controller can calculate the COP (Coefficient of Performance) based on the heat pump's heat output and power consumption, and determine whether to turn on the heat pump based on the electricity price. Then, it controls the electric on / off valve based on whether the heat pump is turned on.

[0084] The controller can use a pre-configured algorithm to calculate the heat production cost based on electricity prices and the heat pump's COP. During periods of high electricity prices, the heat pump's heat production cost is also high. If the cost is higher than that of gas-fired heat production, the heat pump can be shut down during those periods. Conversely, during periods of low electricity prices, the heat pump's heat production cost is lower, meaning it's lower than that of gas-fired heat production. In such cases, the controller can control the opening and closing of the solenoid valve to utilize a manual pump for efficient waste heat recovery from flue gas.

[0085] For example, if the water temperature drops by 10°C, the heat output per ton of water is 1×10⁻⁶. 4 Kcal, assuming the heat pump COP is 3, the heat pump condenser raises the water temperature by 15℃. And assuming the natural gas price is 3 yuan / Nm3 and the gas calorific value is 8300 kcal / Nm3. 3 Boiler efficiency: 0.93.

[0086] The cost of heat production of the boiler is:

[0087] 3x860÷8300÷0.93=0.3342 yuan / kWh.

[0088] Since the COP of the heat pump is 3, as long as the electricity price is lower than 0.3342x3=1.003 yuan / kWh, the heat pump can be started to further recover the flue gas waste heat.

[0089] It can be understood that the above algorithm is only an exemplary explanation of the case of selecting to use or not to use the heat pump, and does not affect the structure of the combined heat pump operated steam boiler flue gas waste heat recovery system of the present application.

[0090] It can be understood that, as shown in Figure 5 and Figure 6 , the present application provides the change of the input water temperature and the output water temperature of the combined heat pump operated steam boiler flue gas waste heat recovery system.

[0091] As shown in Figure 5 and Figure 6 , the combined heat pump operated steam boiler flue gas waste heat recovery system provided by the embodiments of the present application has a 120℃ flue gas temperature and a 40℃ water inlet temperature. The conventional system can raise the water temperature to about 72℃ through the high-efficiency flue gas heat exchanger; under this working condition, the heat pump COP of the system of the present application is generally above 3, which can raise the water temperature to above 87℃, and 1x10 4 Kcal of heat is recovered per ton of water, and as long as the electricity price is lower than 3 times the gas price, the system has application value. The above-mentioned flue gas waste heat recovery amount is increased by more than 31%.

[0092] It can be understood that the system in the embodiments of the present application can be used in systems with small water flow and high temperature rise. For example, the steam boiler inlet water recovers flue gas waste heat, the domestic hot water recovers flue gas waste heat, and some process water recovers flue gas waste heat.

[0093] It is to be understood that the block diagrams in the drawings represent possible architectural, functional and operational architectures of processes, methods and computer program products according to various embodiments of the present application. In this regard, each block in the block diagrams can represent a module, a segment, or a portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the block can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations thereof, can be implemented by special purpose hardware-based computer systems which perform the specified functions or operations, or combinations of special purpose hardware and computer instructions.

[0094] That is, the fuel gun gas-liquid detection device provided by the present application is reasonable in design, high in intelligent degree, high in measurement accuracy, reliable and stable in work, high in safety, and completely applicable to explosive dangerous occasions as an inspection device, convenient and flexible to operate, can better realize the requirements of industry regulations, and has good application and promotion value.

[0095] The above description is merely preferred embodiments of the present application and a description of the technical principles used. Those skilled in the art should understand that the disclosed scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and also covers other technical solutions formed by any combination of the above technical features or equivalent features without departing from the disclosed concept. For example, the technical solutions formed by the mutual replacement of the above features and the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A steam boiler flue gas waste heat recovery system operating in combination with a heat pump, characterized by, The combined heat pump operated steam boiler flue gas waste heat recovery system is used for a steam boiler, and comprises the following: A flue gas heat exchanger and a heat pump; The flue gas heat exchanger is arranged on a flue gas pipeline of the steam boiler; Input and output pipelines are arranged between the flue gas heat exchanger and the heat pump, so that external water is cooled by the heat pump, then transported to the flue gas heat exchanger through the output pipeline for flue gas waste heat recovery, and the water after waste heat recovery is heated by the heat pump and then output to the steam boiler through the input pipeline.

2. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 1, characterized in that, The heat pump is provided with an input pipeline and an output pipeline, the input pipeline is used for inputting external water to the heat pump, and the output pipeline is used for outputting water heated by the heat pump; The input pipeline and the output pipeline are connected through a first pipeline, and the output pipeline and the input pipeline are connected through a second pipeline.

3. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 2, characterized in that, The combined heat pump operated steam boiler flue gas waste heat recovery system further comprises a control valve assembly; The control valve assembly comprises a first water input control valve and a first water output control valve; The water input control valve is arranged on the first pipeline, and the first water output control valve is arranged on the second pipeline.

4. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 3, characterized in that, The control valve assembly further comprises a second water input control valve and a second water output control valve; The second water input control valve is arranged on the output pipeline close to the heat pump, and the second water output control valve is arranged on the output pipeline close to the heat pump.

5. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 4, characterized in that, The combined heat pump operated steam boiler flue gas waste heat recovery system further comprises a control box, and a controller is arranged in the control box and electrically connected with each control valve in the control valve assembly.

6. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 5, characterized in that, The combined heat pump operated steam boiler flue gas waste heat recovery system further comprises at least one temperature sensor; The temperature sensors are arranged at both ends of the output pipeline, both ends of the input pipeline, the input pipeline and the output pipeline; The temperature sensors and a heat meter are electrically connected with the controller.

7. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 6, characterized in that, The combined heat pump operated steam boiler flue gas waste heat recovery system further comprises a heat meter arranged on the output pipeline, and the heat meter is electrically connected with the controller.

8. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 7, characterized in that, The combined heat pump operated steam boiler flue gas waste heat recovery system further comprises an electric meter electrically connected with the controller.

9. The combined heat pump operated steam boiler flue gas heat recovery system according to claim 8, characterized in that, The controller is a PLC, and each control valve in the control valve assembly is an electrically operated switch valve.

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