A direct-fired heat pump heating system and heating method

Abstract

The present application discloses a direct-fired heat pump heating system and a heating method, wherein the direct-fired heat pump heating system comprises a direct-fired heat pump, comprising a first water inlet, a first water outlet and a first flue gas outlet; a spray crystallization tower, comprising a first flue gas inlet, a second flue gas outlet, a second water inlet and a second water outlet; a waste heat recovery tower, comprising a second flue gas inlet, a third flue gas outlet, a third water inlet and a third water outlet; and a solid-liquid separation device, comprising a fourth water inlet, a solid matter outlet and a fourth water outlet. The present application realizes low-cost sewage treatment by absorbing heat from high-temperature flue gas discharged from a direct-fired heat pump, and avoids the adverse effects of high-temperature flue gas directly discharged into the atmosphere on the environment.

Description

Technical Field

[0001] The present application relates to the field of heating technology, and in particular to a heating system and method based on a direct-fired heat pump. Background Art

[0002] In the field of centralized heating, on the one hand, there is the problem of high cost of waste (sewage) water purification and treatment, and on the other hand, there is also the problem of high-temperature flue gas directly discharged into the atmosphere to pollute the environment.

[0003] A heat pump is a device that uses high-grade heat energy as a driving energy source to recover low-grade heat energy for heating or warming. A direct-fired heat pump is a heat pump that is directly driven by natural gas combustion. In places where direct-fired heat pumps are used for central heating, the high-temperature flue gas discharged during the operation of the direct-fired heat pump will have an adverse effect on the atmospheric environment, and the direct discharge of high-temperature flue gas will also cause heat and energy waste. Summary of the invention

[0004] (I) Purpose of the invention

[0005] The purpose of the present application is to provide a direct-fired heat pump heating system, which fully absorbs and utilizes the heat in the high-temperature flue gas while avoiding direct discharge of the high-temperature flue gas of the direct-fired heat pump into the atmosphere.

[0006] (II) Technical solution

[0007] In a first aspect, an embodiment of the present application provides a direct-fired heat pump heating system, comprising:

[0008] A direct-fired heat pump, comprising a first water inlet, a first water outlet and a first flue gas outlet; the first water inlet is used to receive low-temperature hot water, the first water outlet is used to discharge the low-temperature hot water after heat release, and the first flue gas outlet is used to discharge high-temperature flue gas generated by the direct-fired heat pump;

[0009] A spray crystallization tower, comprising a first flue gas inlet, a second flue gas outlet, a second water inlet and a second water outlet; the first flue gas inlet is connected to the first flue gas outlet and is used to receive the high-temperature flue gas, the second water inlet is used to receive wastewater to be treated, the second water outlet is used to discharge wastewater concentrate, and the second flue gas outlet is used to discharge sub-high-temperature flue gas whose temperature is reduced after heat exchange;

[0010] A waste heat recovery tower, comprising a second flue gas inlet, a third flue gas outlet, a third water inlet and a third water outlet; the second flue gas inlet is connected to the second flue gas outlet for receiving the sub-high temperature flue gas, the third flue gas outlet is used to discharge the low temperature flue gas formed after the sub-high temperature flue gas releases heat, the third water outlet is connected to the first water inlet for outputting the low temperature hot water that absorbs the heat of the sub-high temperature flue gas, and the third water inlet is connected to the first outlet for receiving the low temperature water after heat release;

[0011] The solid-liquid separation device comprises a fourth water inlet, a solid matter outlet and a fourth water outlet; the fourth water inlet is connected to the second water outlet for receiving the wastewater concentrate, the solid matter outlet is used to discharge the solid matter formed by solid-liquid separation of the wastewater concentrate, and the fourth water outlet is used to discharge the separated liquid formed by solid-liquid separation of the wastewater concentrate.

[0012] In a second aspect, an embodiment of the present application provides a direct-fired heat pump heating method, comprising:

[0013] Provide high-temperature hot water to the heating network through direct-fired heat pumps, and output high-temperature flue gas;

[0014] The high-temperature flue gas is received by a spray crystallization tower, and the high-temperature flue gas is contact-heat-exchanged with the wastewater sprayed and released in the spray crystallization tower to form a wastewater concentrate and a sub-high-temperature flue gas with a reduced temperature;

[0015] receiving the sub-high temperature flue gas and low temperature hot water from the direct-fired heat pump through a waste heat recovery tower, and utilizing the low temperature hot water to absorb waste heat in the sub-high temperature flue gas through heat exchange;

[0016] Sending the low-temperature hot water that has absorbed the waste heat of the sub-high-temperature flue gas back to the direct-fired heat pump;

[0017] Outputting the low-temperature hot water after heat exchange and cooling in the direct-fired heat pump to the waste heat recovery tower again;

[0018] The wastewater concentrate formed in the spray crystallization tower is separated into solid and liquid by a solid-liquid separation device.

[0019] (III) Beneficial effects

[0020] The beneficial effect of the technical solution of the present application is that by absorbing the heat in the high-temperature flue gas discharged by the direct-fired heat pump, low-cost sewage treatment is achieved, and the adverse impact of direct discharge of high-temperature flue gas into the atmosphere on the environment is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the system structure of an embodiment of the heating system of the present application;

[0022] Figure 2 is a schematic diagram of the system structure of another embodiment of the heating system of the present application;

[0023] Figure 3 yes Figure 2 A schematic diagram of the improved system structure of the embodiment;

[0024] Figure 4 is a schematic diagram of the system structure of another embodiment of the heating system of the present application;

[0025] Figure 5 yes Figure 4 A schematic diagram of the improved system structure of the embodiment;

[0026] Figure 6 is a schematic diagram of the system structure of another embodiment of the heating system of the present application;

[0027] Figure 7 is a schematic diagram of the system structure of another embodiment of the heating system of the present application;

[0028] Figure 8 It is a flow chart of the heating method of the present application.

[0029] Reference numerals:

[0030] 10: direct-fired heat pump; 11: first water inlet; 12: first water outlet; 13: first flue gas outlet.

[0031] 20: spray crystallization tower; 21: first flue gas inlet; 22: second flue gas outlet; 23: second water inlet; 24: second water outlet, 25: circulating water outlet; 26: circulating water inlet; 27: external high-temperature flue gas inlet.

[0032] 200: Circulation pump.

[0033] 30: waste heat recovery tower; 31: second flue gas inlet; 32: third flue gas outlet; 33: third water inlet; 34: third water outlet; 35: fifth water outlet; 36: ninth water outlet; 37: external medium-temperature flue gas inlet.

[0034] 40: solid-liquid separation device; 41: fourth water inlet; 42: solid matter outlet; 43: fourth water outlet.

[0035] 50: evaporation device; 51: sixth water inlet; 52: sixth water outlet; 53: seventh water inlet; 54: seventh water outlet; 55: eighth water outlet.

[0036] 500: Heating device. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with specific implementations and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present application.

[0038] Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0039] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0040] Figure 1 It is a schematic diagram of the system structure of an embodiment of the heating system of the present application.

[0041] like Figure 1 As shown, a direct-fired heat pump heating system comprises:

[0042] The direct-fired heat pump 10 comprises a first water inlet 11, a first water outlet 12 and a first flue gas outlet 13; the first water inlet 11 is used to receive low-temperature hot water, the first water outlet 12 is used to discharge the low-temperature hot water after heat release, and the first flue gas outlet 13 is used to discharge the high-temperature flue gas generated by the direct-fired heat pump;

[0043] The spray crystallization tower 20 includes a first flue gas inlet 21, a second flue gas outlet 22, a second water inlet 23 and a second water outlet 24; the first flue gas inlet 21 is connected to the first flue gas outlet 13 and is used to receive the high-temperature flue gas, the second water inlet 23 is used to receive the wastewater to be treated, the second water outlet 24 is used to discharge the wastewater concentrate, and the second flue gas outlet 22 is used to discharge the sub-high-temperature flue gas whose temperature is reduced after heat exchange;

[0044] The waste heat recovery tower 30 includes a second flue gas inlet 31, a third flue gas outlet 32, a third water inlet 33 and a third water outlet 34; the second flue gas inlet 31 is connected to the second flue gas outlet 22 for receiving the sub-high temperature flue gas, the third flue gas outlet 32 ​​is used to discharge the low temperature flue gas formed after the sub-high temperature flue gas releases heat, the third water outlet 34 is connected to the first water inlet 11 for outputting the low temperature hot water that absorbs the heat of the sub-high temperature flue gas, and the third water inlet 33 is connected to the first outlet 12 for receiving the low temperature water after heat release;

[0045] The solid-liquid separation device 40 includes a fourth water inlet 41, a solid matter outlet 42 and a fourth water outlet 43; the fourth water inlet 41 is connected to the second water outlet 24 for receiving the wastewater concentrate, the solid matter outlet 42 is used to discharge the solid matter formed by the solid-liquid separation of the wastewater concentrate, and the fourth water outlet 43 is used to discharge the separated liquid formed by the solid-liquid separation of the wastewater concentrate.

[0046] The direct-fired heat pump heating system of this embodiment can achieve zero sewage discharge while providing heat, and can purify wastewater while providing heat, thereby significantly reducing energy consumption costs.

[0047] In some embodiments, Figure 1 As shown, the waste heat recovery tower 30 is a partition-type waste heat recovery tower, and a fifth water outlet 35 is provided at the bottom of the waste heat recovery tower for discharging condensed water formed when the sub-high temperature flue gas releases heat in the waste heat recovery tower.

[0048] When the waste heat recovery tower 30 is a partition-type waste heat recovery tower, the sub-high temperature flue gas performs non-contact heat exchange with the low temperature hot water entering the waste heat recovery tower 30 , and the sub-high temperature flue gas forms condensed water during the heat release process and is discharged from the fifth water outlet 35 .

[0049] Figure 2 It is a schematic diagram of the system structure of another embodiment of the heating system of the present application.

[0050] In some embodiments, Figure 2 As shown, the waste heat recovery tower 30 is a spray type waste heat recovery tower, and a fifth water outlet 35 is provided at the bottom of the waste heat recovery tower 30 for discharging the low-temperature hot water released by spraying in the waste heat recovery tower 30, and the incremental part of the low-temperature hot water formed after absorbing the moisture of the sub-high temperature flue gas. The fifth water outlet 35 is connected to the second water inlet 23, and is used to send the incremental part of the low-temperature hot water into the spray crystallization tower 20 as wastewater to be treated.

[0051] When the waste heat recovery tower 30 is a spray type waste heat recovery tower, the sub-high temperature flue gas undergoes contact heat exchange with the low temperature hot water entering the waste heat recovery tower 30. When the low temperature hot water is released in the waste heat recovery tower in a spraying manner, it absorbs the waste heat and moisture in the sub-high temperature flue gas. The low temperature hot water will increase in both mass and temperature, and the incremental low temperature hot water formed will be discharged from the fifth water outlet 35 as waste water to be treated, and will be sent to the spray crystallization tower 20 through the second water inlet 23.

[0052] Figure 3 yes Figure 2 Schematic diagram of the improved system structure of the embodiment.

[0053] In some embodiments, Figure 3As shown, the waste heat recovery tower 30 is a spray type waste heat recovery tower, and a ninth water outlet 36 is provided on the connecting pipe between the third water outlet 34 of the waste heat recovery tower 30 and the first water inlet 11 of the direct-fired heat pump, which is used to discharge the low-temperature hot water sprayed and released in the waste heat recovery tower 30, and the incremental part of the low-temperature hot water formed after absorbing the moisture of the sub-high temperature flue gas. The ninth water outlet 36 is connected to the second water inlet 23, and is used to send the incremental part of the low-temperature hot water into the spray crystallization tower as wastewater to be treated.

[0054] Figure 3 Example and Figure 2 The embodiments differ only in that Figure 3 In the embodiment, the ninth water outlet for discharging the incremental low-temperature hot water is arranged on the connecting pipe between the third water outlet 34 and the first water inlet 11, rather than being arranged at the bottom of the waste heat recovery tower 30. The advantage of being arranged on the connecting pipe is that there is no need to make any modification to the waste heat recovery tower 30, but only a three-way valve needs to be installed on the connecting pipe, which is relatively easier to implement.

[0055] Figure 4 It is a schematic diagram of the system structure of another embodiment of the heating system of the present application.

[0056] In some embodiments, Figure 4 As shown, the heating system also includes an evaporation device 50, which includes a sixth water inlet 51, a sixth water outlet 52, a seventh water inlet 53, a seventh water outlet 54 and an eighth water outlet 55; the sixth water inlet 51 is connected to the fifth water outlet 35, and the sixth water outlet 52 is connected to the second water inlet 23; the seventh water inlet 53 receives heat medium from a low-quality heat source outside the system, and the seventh water outlet 54 returns the heat medium after heat release to the low-quality heat source; the eighth water outlet 55 discharges steam condensed water formed in the evaporation device.

[0057] In this embodiment, the evaporation device 50 is mainly provided to fully utilize the external low-quality heat source. The evaporation device 50 can absorb and convert the heat of the external low-quality heat source for evaporation treatment of the untreated wastewater discharged from the fifth water outlet 35, so that the untreated wastewater is concentrated, heated and forms steam condensate.

[0058] In this embodiment, the fifth water outlet is Figure 3 In the case of the embodiment, it may be a ninth water outlet provided on the communication pipe between the third water outlet 34 and the first water inlet 11 .

[0059] Figure 5 yes Figure 4 Schematic diagram of the improved system structure of the embodiment.

[0060] In some embodiments, Figure 5 As shown, the heating system also includes an evaporation device 50, which includes a sixth water inlet 51, a sixth water outlet 52, an eighth water outlet 55 and a heating device 500; the sixth water inlet 51 is connected to the fifth water outlet 35, and the sixth water outlet 52 is connected to the second water inlet 23; the heating device 500 is used to heat the liquid entering the evaporation device to form a concentrated liquid discharged from the sixth water outlet 51 and steam condensed water discharged from the eighth water outlet 55.

[0061] Figure 5 Example and Figure 4 The difference between the embodiments is mainly that Figure 5 In the embodiment, no external low-quality heat source is introduced, but a heating device 500 is directly added inside or near the outside of the evaporation device 50 to heat the untreated wastewater discharged from the fifth water outlet 35 and generate concentrated liquid and steam condensate.

[0062] Figure 6 It is a schematic diagram of the system structure of another embodiment of the heating system of the present application.

[0063] In some embodiments, Figure 6 As shown, the spray crystallization tower 20 also includes a circulating water outlet 25 arranged on its lower side and a circulating water inlet 26 arranged on its upper side, and a circulating pump 200 arranged at the bottom of the spray crystallization tower 20, and the circulating pump 200 circulates the wastewater concentrate to the circulating water inlet 26 through the circulating water outlet 25.

[0064] In this embodiment, the circulating water outlet 25, the circulating water inlet 26 and the circulating pump 200 are provided so that the wastewater that has not been fully concentrated can be repeatedly concentrated in the spray crystallization tower 20 through heat exchange with the high-temperature flue gas, and the situation that the high-temperature flue gas cannot be cooled when the wastewater to be treated is insufficiently supplied can be avoided.

[0065] Figure 7 It is a schematic diagram of the system structure of another embodiment of the heating system of the present application.

[0066] In some embodiments, Figure 7 As shown, the heating system further includes an external medium-temperature flue gas inlet 37 for inputting medium-temperature flue gas from outside the system into the waste heat recovery tower 30 .

[0067] In some embodiments, Figure 7 As shown, the heating system further includes an external high-temperature flue gas inlet 27 for inputting high-temperature flue gas from outside the system into the spray crystallization tower 20 .

[0068] In some embodiments, Figure 2-7 As shown in any one of the figures, the fourth water outlet 41 is connected to the second water inlet 23, and is used to supply the separated liquid separated by the solid-liquid separation device 40 to the spray crystallization tower 20 again as wastewater to be treated.

[0069] Figure 8 It is a flow chart of the heating method of the present application.

[0070] like Figure 8 As shown, a direct-fired heat pump heating method comprises:

[0071] S110: Provides high-temperature hot water to the heating network through a direct-fired heat pump, and also outputs high-temperature flue gas.

[0072] S120: receiving the high-temperature flue gas through a spray crystallization tower, and causing the high-temperature flue gas to undergo contact heat exchange with wastewater sprayed and released into the spray crystallization tower, thereby forming a wastewater concentrate and sub-high-temperature flue gas with a reduced temperature.

[0073] Step S120 utilizes wastewater to cool down and remove dust from high-temperature flue gas, and also concentrates the wastewater.

[0074] S130: receiving the sub-high temperature flue gas and the low temperature hot water from the direct-fired heat pump through a waste heat recovery tower, and using the low temperature hot water to absorb waste heat in the sub-high temperature flue gas through heat exchange;

[0075] Step S130 uses low-temperature hot water from the direct-fired heat pump to further cool the sub-high-temperature flue gas. The waste heat recovery tower can be a partition type or a spray type.

[0076] S140: Outputting the low-temperature hot water that has absorbed the heat and moisture of the sub-high-temperature flue gas to the direct-fired heat pump;

[0077] In step S140, the low-temperature hot water whose temperature has risen after absorbing the waste heat of the sub-high-temperature flue gas is sent to the direct-fired heat pump again, and the heat recovery of the low-quality heat source in the waste heat recovery tower is realized by using the direct-fired heat pump.

[0078] S150: Outputting the low-temperature hot water after heat exchange and cooling in the direct-fired heat pump to the waste heat recovery tower again;

[0079] Step S150 realizes the repeated use of low-temperature hot water.

[0080] S160: performing solid-liquid separation on the wastewater concentrate formed in the spray crystallization tower through a solid-liquid separation device.

[0081] Step S160 uses a solid-liquid separation device to further reduce the emission of pollutants. Moreover, the separated liquid can be sent to the spray crystallization again as wastewater to be treated.

[0082] In some embodiments, Figure 8 As shown, it also includes:

[0083] S170: receiving a heat medium from a low-quality heat source outside the system through an evaporation device, and utilizing the heat medium to heat the low-temperature hot water entering the evaporation device.

[0084] Step S170 mainly utilizes the external low-quality heat source through the evaporation device, and evaporates the low-temperature hot water as the wastewater to be treated by absorbing and converting the heat of the external low-quality heat source, so that the wastewater to be treated is concentrated, heated and forms steam condensed water.

[0085] It should be understood that the above specific embodiments of the present application are only used to illustrate or explain the principles of the present application, and do not constitute a limitation to the present application. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present application should be included in the protection scope of the present application. In addition, the claims attached to the present application are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A direct-fired heat pump heating system, characterized in that: include: A direct-fired heat pump comprising a first water inlet, a first water outlet and a first flue gas outlet; The first water inlet is used to receive low-temperature hot water, the first water outlet is used to discharge the low-temperature hot water after heat release, and the first flue gas outlet is used to discharge the high-temperature flue gas generated by the direct-fired heat pump; A spray crystallization tower, comprising a first flue gas inlet, a second flue gas outlet, a second water inlet and a second water outlet; the first flue gas inlet is connected to the first flue gas outlet and is used to receive the high-temperature flue gas, the second water inlet is used to receive wastewater to be treated, the second water outlet is used to discharge wastewater concentrate, and the second flue gas outlet is used to discharge sub-high-temperature flue gas whose temperature is reduced after heat exchange; A waste heat recovery tower, comprising a second flue gas inlet, a third flue gas outlet, a third water inlet and a third water outlet; the second flue gas inlet is connected to the second flue gas outlet for receiving the sub-high temperature flue gas, the third flue gas outlet is used to discharge the low temperature flue gas formed after the sub-high temperature flue gas releases heat, the third water outlet is connected to the first water inlet for outputting the low temperature hot water that absorbs the heat of the sub-high temperature flue gas, and the third water inlet is connected to the first outlet for receiving the low temperature water after heat release; The solid-liquid separation device comprises a fourth water inlet, a solid matter outlet and a fourth water outlet; the fourth water inlet is connected to the second water outlet for receiving the wastewater concentrate, the solid matter outlet is used to discharge the solid matter formed by solid-liquid separation of the wastewater concentrate, and the fourth water outlet is used to discharge the separated liquid formed by solid-liquid separation of the wastewater concentrate.

2. The heating system according to claim 1, characterized in that: The waste heat recovery tower is a partition-type waste heat recovery tower, and a fifth water outlet is provided at the bottom of the waste heat recovery tower for discharging condensed water formed when the sub-high temperature flue gas releases heat in the waste heat recovery tower.

3. The heating system according to claim 1, characterized in that: The waste heat recovery tower is a spray type waste heat recovery tower, and a fifth water outlet is provided at the bottom of the waste heat recovery tower for discharging the low-temperature hot water released by spraying in the waste heat recovery tower, and the incremental part of the low-temperature hot water formed after absorbing the moisture of the sub-high temperature flue gas. The fifth water outlet is connected with the second water inlet, and is used to send the incremental part of the low-temperature hot water into the spray crystallization tower as wastewater to be treated.

4. The heating system according to claim 1, characterized in that: The waste heat recovery tower is a spray type waste heat recovery tower, and a ninth water outlet is provided on the connecting pipe between the third water outlet of the waste heat recovery tower and the first water inlet of the direct-fired heat pump, which is used to discharge the low-temperature hot water released by spraying in the waste heat recovery tower, and the incremental part of the low-temperature hot water formed after absorbing the moisture of the sub-high temperature flue gas. The ninth water outlet is connected to the second water inlet, and is used to send the incremental part of the low-temperature hot water into the spray crystallization tower as wastewater to be treated.

5. The heating system according to claim 1, characterized in that: It also includes an evaporation device, which includes a sixth water inlet, a sixth water outlet, a seventh water inlet, a seventh water outlet and an eighth water outlet; the sixth water inlet is connected to the fifth water outlet, and the sixth water outlet is connected to the second water inlet; the seventh water inlet receives heat medium from a low-quality heat source outside the system, and the seventh water outlet returns the heat medium after heat release to the low-quality heat source; the eighth water outlet discharges steam condensate formed in the evaporation device.

6. The heating system according to claim 1, characterized in that: It also includes an evaporation device, which includes a sixth water inlet, a sixth water outlet, an eighth water outlet and a heating device; the sixth water inlet is connected to the fifth water outlet, and the sixth water outlet is connected to the second water inlet; the heating device is used to heat the liquid entering the evaporation device to form a concentrated liquid discharged from the sixth water outlet and steam condensed water discharged from the eighth water outlet.

7. The heating system according to claim 1, characterized in that: The fourth water outlet is connected to the second water inlet, and is used to supply the separated liquid separated by the solid-liquid separation device to the spray crystallization tower again as wastewater to be treated.

8. The heating system according to claim 1, characterized in that: The spray crystallization tower also includes a circulating water outlet arranged at its lower side and a circulating water inlet arranged at its upper side, and a circulating pump arranged at the bottom of the spray crystallization tower, and the circulating pump circulates the wastewater concentrate to the circulating water inlet through the circulating water outlet.

9. The heating system according to claim 1, characterized in that: Also includes: The external medium-temperature flue gas inlet is used to input the medium-temperature flue gas from outside the system into the waste heat recovery tower.

10. The heating system according to claim 1, characterized in that: Also includes: The external high-temperature flue gas inlet is used to input the high-temperature flue gas from outside the system into the spray crystallization tower.

11. A direct-fired heat pump heating method, characterized in that: include: Provide high-temperature hot water to the heating network through direct-fired heat pumps, and output high-temperature flue gas; The high-temperature flue gas is received by a spray crystallization tower, and the high-temperature flue gas is contact-heat-exchanged with the wastewater sprayed and released in the spray crystallization tower to form a wastewater concentrate and a sub-high-temperature flue gas with a reduced temperature; receiving the sub-high temperature flue gas and low temperature hot water from the direct-fired heat pump through a waste heat recovery tower, and utilizing the low temperature hot water to absorb waste heat in the sub-high temperature flue gas through heat exchange; The low-temperature hot water that has absorbed the waste heat of the sub-high-temperature flue gas is sent back to the direct-fired heat pump; Outputting the low-temperature hot water after heat exchange and cooling in the direct-fired heat pump to the waste heat recovery tower again; The wastewater concentrate formed in the spray crystallization tower is separated into solid and liquid by a solid-liquid separation device.

12. The heating method according to claim 11, characterized in that: The evaporation device receives heat medium from a low-quality heat source outside the system, and utilizes the heat medium to heat the low-temperature hot water entering the evaporation device.

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