Absorption and compression open type flue gas total heat recovery system

Abstract

The invention relates to an absorption and compression open type flue gas total heat recovery system, which belongs to the technical field of waste heat recovery and comprises a water supply and return pipe and a high-temperature steam pipe, and an absorption and compression heat pump unit and a steam compression heat pump unit are arranged between the water supply and return pipe and the high-temperature steam pipe. The system further comprises a high-temperature flue gas pipe, an auxiliary heat source loop and a low-temperature hot water loop. The high-temperature steam pipe firstly enters the generator, then is directly connected with the absorber and is respectively used for recovering sensible heat and total heat of flue gas; the steam compression heat pump unit exchanges heat with the generator through the auxiliary heat source loop and is used for providing insufficient heat in the solution generation process; and the low-temperature hot water loop is used for supplying heat released by the flue gas at the low-temperature section to a heat user. The flue gas heat recovery device has the advantages of being high in heat recovery efficiency, adjustable in output heat parameter and capable of recovering clean condensed water.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery, and in particular to an absorption and compression open flue gas full heat recovery system. Background Art

[0002] Gas-fired boilers are important heat sources in industrial production, but high-temperature flue gas emissions result in significant energy waste. Traditional flue gas waste heat recovery methods are limited by the flue gas dew point, preventing the effective recovery of latent heat in the flue gas. This results in low waste heat recovery efficiency and the susceptibility to plume. Furthermore, the quality of recovered waste heat is limited by the flue gas temperature, making it unable to meet the high-quality heat demand in production.

[0003] The first type of absorption heat pump exploits the deviation in the refrigerant's saturation partial pressure at different working fluid temperatures. By inputting a small amount of high-temperature heat, it transfers heat from a low-temperature heat source to a medium-temperature heat source, thereby increasing medium-temperature thermal energy. By coupling a compression component or vapor compression system, the output heat energy quality can be flexibly adjusted while reducing the temperature requirement for the high-quality heat source. Therefore, absorption-compression hybrid heat pump systems hold great promise for flue gas waste heat recovery.

[0004] Patent publication number CN115711401A, titled "A Low-Grade Flue Gas Waste Heat Recovery System Based on an Absorption Heat Pump," discloses a low-grade flue gas waste heat recovery system. This system utilizes exhaust steam from a boiler turbine to drive an absorption heat pump, employs spray water for heat and mass exchange with the flue gas, and simultaneously exchanges return water from the spray tower with the evaporator of the absorption heat pump to recover waste heat from the flue gas. However, the indirect heat exchange between the flue gas and the heat pump system reduces heat recovery efficiency and makes it impossible to adjust the quality of the output heat energy.

[0005] The patent document with publication number CN116772268 A and invention name "Deep recovery system of flue gas waste heat of composite heat pump" discloses a composite flue gas heat recovery system. The device divides the spray tower into two sections, high temperature and low temperature, and uses an absorption heat pump system, a steam compression heat pump system, and a circulating water system in parallel to perform gradient waste heat recovery on the flue gas in the spray tower. However, the flue gas is in a saturated state when discharged, and there is still a risk of white plume phenomenon, and the water vapor in the flue gas cannot be recovered in a clean manner. Summary of the Invention

[0006] This invention primarily addresses the shortcomings of the existing technology by providing an absorption and compression open flue gas full heat recovery system and its control method. The system features high heat recovery efficiency, adjustable output heat parameters, and the ability to recover clean condensate water, achieving deep recovery of both sensible and latent heat from flue gas.

[0007] The above technical problems of the present invention are mainly solved by the following technical solutions: An absorption and compression open flue gas full heat recovery system includes a water supply and return pipe and a high-temperature steam pipe, between which an absorption and compression heat pump unit and a steam compression heat pump unit are arranged.

[0008] The absorption and compression heat pump unit includes a generator, a solution heat exchanger, a first solution filter, a solution throttle valve, an absorber, a second solution filter, a solution pump, a first steam compressor, and a steam shut-off valve. The solution outlet of the generator is connected to the concentrated solution inlet of the solution heat exchanger, the concentrated solution outlet of the solution heat exchanger is connected to the first solution filter, the first solution filter is connected to the solution pump, the solution pump is connected to the solution inlet of the absorber, the solution outlet of the absorber is connected to the second solution filter, the second solution filter is connected to the solution throttle valve, the solution throttle valve is connected to the dilute solution inlet of the solution heat exchanger, the dilute solution outlet of the solution heat exchanger is connected to the solution inlet of the generator, the steam outlet of the generator is connected to the inlet of the first steam compressor, the outlet of the first steam compressor is connected to the steam shut-off valve, and the steam shut-off valve is connected to the high-temperature steam pipe.

[0009] The vapor compression heat pump unit includes a second steam compressor, a condenser, a refrigerant throttle valve, a first evaporator, and a second evaporator. The outlet of the second steam compressor is connected to the refrigerant inlet of the condenser, the refrigerant outlet of the condenser is connected to the refrigerant throttle valve, the refrigerant throttle valve is connected to the inlet of the first evaporator, the outlet of the first evaporator is connected to the refrigerant inlet of the second evaporator, and the refrigerant outlet of the second evaporator is connected to the inlet of the second steam compressor.

[0010] Preferably, the generator is connected to a high-temperature flue gas pipe, a flue gas pipeline valve is provided on the high-temperature flue gas pipe, a chimney is provided at the end of the high-temperature flue gas pipe, and the high-temperature flue gas heat exchange pipe inlet in the generator, the flue gas heat exchange pipe outlet in the generator, the flue gas inlet of the absorber, the flue gas outlet of the absorber, the internal flue gas heat exchange pipe inlet of the second evaporator, and the internal flue gas heat exchange pipe outlet of the second evaporator are connected in sequence between the high-temperature flue gas pipe and the chimney.

[0011] Preferably, an auxiliary heat source circuit is further included, which includes a heat medium pump, a first heat medium pipeline valve, and a second heat medium pipeline valve. The heat medium pump outlet is connected to the heat medium heat exchange pipe inlet in the generator through the first heat medium pipeline valve, the heat medium heat exchange pipe outlet in the generator is connected to the heat exchange pipe inlet in the condenser through the second heat medium pipeline valve, and the heat exchange pipe outlet in the condenser is connected to the heat medium pump inlet.

[0012] Preferably, it also includes a low-temperature hot water circuit, which includes a hot water circulation pump, a water supply pipeline valve, and a return pipeline valve. The outlet of the hot water circulation pump is connected to the supply and return pipes through the water supply pipeline valve, and the supply and return pipes are connected to the inlet of the heat exchange pipe in the absorber through the return pipeline valve. The outlet of the heat exchange pipe in the absorber is connected to the inlet of the hot water circulation pump.

[0013] Preferably, a drain valve is provided at the lower end of the absorber to discharge dirt in the absorber.

[0014] Preferably, the first evaporator is a finned tube evaporator, and the first evaporator is provided with a fan for forced convection heat exchange with the air in the environment.

[0015] The present invention can achieve the following effects: The present invention exchanges flue gas with the solution in the generator and absorber indirectly and directly in turn, which can effectively recover both sensible heat and latent heat in the flue gas. Compared with traditional flue gas waste heat recovery methods, it has the characteristic of high heat recovery efficiency.

[0016] The present invention adopts a serial steam compressor mode to increase the steam pressure and temperature at the outlet of the absorption heat pump system generator, and adopts a wet method to recover the absorption heat in the absorber, which has the advantages of diverse heat output forms and adjustable parameters.

[0017] The smoke exhaust of the present invention is in an unsaturated state, which can effectively suppress the generation of the white plume phenomenon and can recover the water vapor in the smoke for clean recovery.

[0018] The present invention is driven by flue gas with a temperature below 100°C, and outputs low-temperature hot water with a temperature of 35-45°C and superheated steam with a pressure of more than 3 Bar. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] In the figure: first steam compressor 1, high-temperature flue gas pipe 2, flue gas pipeline valve 3, generator 4, first heat medium pipeline valve 5, second heat medium pipeline valve 6, heat medium pump 7, condenser 8, chimney 9, second steam compressor 10, second evaporator 11, refrigerant throttle valve 12, first evaporator 13, solution heat exchanger 14, first solution filter 15, solution pump 16, drain valve 17, absorber 18, hot water circulation pump 19, second solution filter 20, return pipeline valve 21, return pipeline valve 22, supply and return water pipe 23, high-temperature steam pipe 24, solution throttle valve 25, steam shut-off valve 26. DETAILED DESCRIPTION

[0021] The technical solution of the invention is further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0022] Example: Figure 1 As shown, an absorption and compression open flue gas full heat recovery system includes a supply and return water pipe 23 and a high-temperature steam pipe 24, and an absorption and compression heat pump unit and a steam compression heat pump unit are arranged between the supply and return water pipe 23 and the high-temperature steam pipe 24.

[0023] The absorption and compression heat pump unit includes a generator 4, a solution heat exchanger 14, a first solution filter 15, a solution throttle valve 25, an absorber 18, a second solution filter 20, a solution pump 16, a first steam compressor 1, and a steam shut-off valve 26. A drain valve 17 is provided at the lower end of the absorber 18 to discharge dirt in the absorber. The solution outlet of the generator 4 is connected to the concentrated solution inlet of the solution heat exchanger 14, the concentrated solution outlet of the solution heat exchanger (14) is connected to the first solution filter 15, the first solution filter 15 is connected to the solution pump 16, the solution pump 16 is connected to the solution inlet of the absorber 18, the solution outlet of the absorber 18 is connected to the second solution filter 20, the second solution filter 20 is connected to the solution throttle valve 25, the solution throttle valve 25 is connected to the dilute solution inlet of the solution heat exchanger 14, the dilute solution outlet of the solution heat exchanger 14 is connected to the solution inlet of the generator 4, the steam outlet of the generator 4 is connected to the inlet of the first steam compressor 1, the outlet of the first steam compressor 1 is connected to the steam shut-off valve 26, and the steam shut-off valve 26 is connected to the high-temperature steam pipe 24.

[0024] It also includes an auxiliary heat source circuit, which includes a heat medium pump 7, a first heat medium pipeline valve 5, and a second heat medium pipeline valve 6. The outlet of the heat medium pump 7 is connected to the inlet of the heat medium heat exchange pipe in the generator 4 through the first heat medium pipeline valve 5, and the outlet of the heat medium heat exchange pipe in the generator 5 is connected to the inlet of the heat exchange pipe in the condenser 8 through the second heat medium pipeline valve 6. The outlet of the heat exchange pipe in the condenser 5 is connected to the inlet of the heat medium pump 7.

[0025] It also includes a low-temperature hot water circuit, which includes a hot water circulation pump 19, a water supply pipeline valve 22, and a return pipeline valve 21. The outlet of the hot water circulation pump 19 is connected to the supply and return pipes 23 through the water supply pipeline valve 22. The supply and return pipes 23 are connected to the inlet of the heat exchange pipe in the absorber 18 through the return pipeline valve 21. The outlet of the heat exchange pipe in the absorber 18 is connected to the inlet of the hot water circulation pump 19.

[0026] The vapor compression heat pump unit includes a second vapor compressor 10, a condenser 8, a refrigerant throttle valve 12, a first evaporator 13, and a second evaporator 11. The first evaporator 13 is a finned tube evaporator and is equipped with a fan for forced convection heat exchange with ambient air. The outlet of the second vapor compressor 10 is connected to the refrigerant inlet of the condenser 8, the refrigerant outlet of the condenser 8 is connected to the refrigerant throttle valve 12, the refrigerant throttle valve 12 is connected to the inlet of the first evaporator 13, the outlet of the first evaporator 13 is connected to the refrigerant inlet of the second evaporator 11, and the refrigerant outlet of the second evaporator 11 is connected to the inlet of the second vapor compressor 10.

[0027] The generator 4 is connected to a high-temperature flue gas pipe 2, which is provided with a flue gas pipeline valve 3. A chimney 9 is provided at the end of the high-temperature flue gas pipe 2. The high-temperature flue gas pipe 2 and the chimney 9 are connected in sequence to the flue gas heat exchange pipe inlet in the generator 4, the flue gas heat exchange pipe outlet in the generator 4, the flue gas inlet of the absorber 18, the flue gas outlet of the absorber 18, the internal flue gas heat exchange pipe inlet of the second evaporator 11, and the internal flue gas heat exchange pipe outlet of the second evaporator 11.

[0028] In summary, this absorption and compression open-loop flue gas total heat recovery system involves the flue gas pipeline first entering the generator and then directly connecting to the absorber, respectively, to recover the sensible heat and total heat of the flue gas. A vapor compression heat pump unit exchanges heat with the generator via an auxiliary heat source circuit, providing insufficient heat for the solution generation process. A low-temperature hot water circuit supplies heat released by the flue gas at low temperatures to heat users. This system features high heat recovery efficiency, adjustable heat output parameters, and the ability to recover clean condensate, achieving comprehensive recovery of both sensible and latent heat from the flue gas.

[0029] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in this field within the scope of the present invention are included in the patent scope of the present invention.

Claims

1. An absorption and compression open flue gas full heat recovery system, characterized by: It comprises a water supply and return pipe (23) and a high-temperature steam pipe (24), wherein an absorption and compression heat pump unit and a steam compression heat pump unit are provided between the water supply and return pipe (23) and the high-temperature steam pipe (24); The absorption and compression heat pump unit comprises a generator (4), a solution heat exchanger (14), a first solution filter (15), a solution throttle valve (25), an absorber (18), a second solution filter (20), a solution pump (16), a first steam compressor (1), and a steam shut-off valve (26). The solution outlet of the generator (4) is connected to the concentrated solution inlet of the solution heat exchanger (14), the concentrated solution outlet of the solution heat exchanger (14) is connected to the first solution filter (15), the first solution filter (15) is connected to the solution pump (16), and the solution pump (16) The solution inlet of the absorber (18) is connected, the solution outlet of the absorber (18) is connected to the second solution filter (20), the second solution filter (20) is connected to the solution throttle valve (25), the solution throttle valve (25) is connected to the dilute solution inlet of the solution heat exchanger (14), the dilute solution outlet of the solution heat exchanger (14) is connected to the solution inlet of the generator (4), the steam outlet of the generator (4) is connected to the inlet of the first steam compressor (1), the outlet of the first steam compressor (1) is connected to the steam shut-off valve (26), and the steam shut-off valve (26) is connected to the high-temperature steam pipe (24); The vapor compression heat pump unit comprises a second vapor compressor (10), a condenser (8), a refrigerant throttle valve (12), a first evaporator (13), and a second evaporator (11), wherein the outlet of the second vapor compressor (10) is connected to the refrigerant inlet of the condenser (8), the refrigerant outlet of the condenser (8) is connected to the refrigerant throttle valve (12), the refrigerant throttle valve (12) is connected to the inlet of the first evaporator (13), the outlet of the first evaporator (13) is connected to the refrigerant inlet of the second evaporator (11), and the refrigerant outlet of the second evaporator (11) is connected to the inlet of the second vapor compressor (10).

2. The absorption and compression open flue gas full heat recovery system according to claim 1 is characterized in that: The generator (4) is connected to a high-temperature flue gas pipe (2), a flue gas pipe valve (3) is provided on the high-temperature flue gas pipe (2), a chimney (9) is provided at the end of the high-temperature flue gas pipe (2), and the high-temperature flue gas pipe (2) and the chimney (9) are connected in sequence to the flue gas heat exchange pipe inlet in the generator (4), the flue gas heat exchange pipe outlet in the generator (4), the flue gas inlet of the absorber (18), the flue gas outlet of the absorber (18), the internal flue gas heat exchange pipe inlet of the second evaporator (11), and the internal flue gas heat exchange pipe outlet of the second evaporator (11).

3. The absorption and compression open flue gas full heat recovery system according to claim 1 is characterized in that: The auxiliary heat source circuit also includes an auxiliary heat source circuit, which includes a heat medium pump (7), a first heat medium pipeline valve (5), and a second heat medium pipeline valve (6). The outlet of the heat medium pump (7) is connected to the inlet of the heat medium heat exchange pipe in the generator (4) through the first heat medium pipeline valve (5), the outlet of the heat medium heat exchange pipe in the generator (5) is connected to the inlet of the heat exchange pipe in the condenser (8) through the second heat medium pipeline valve (6), and the outlet of the heat exchange pipe in the condenser (5) is connected to the inlet of the heat medium pump (7).

4. The absorption and compression open flue gas full heat recovery system according to claim 1 is characterized in that: The invention also includes a low-temperature hot water circuit, which includes a hot water circulation pump (19), a water supply pipeline valve (22), and a return pipeline valve (21). The outlet of the hot water circulation pump (19) is connected to the supply and return water pipes (23) via the water supply pipeline valve (22). The supply and return water pipes (23) are connected to the inlet of the heat exchange pipe in the absorber (18) via the return pipeline valve (21). The outlet of the heat exchange pipe in the absorber (18) is connected to the inlet of the hot water circulation pump (19).

5. The absorption and compression open flue gas full heat recovery system according to claim 1 is characterized in that: The lower end of the absorber (18) is provided with a drain valve (17) for draining dirt from the absorber.

6. The absorption and compression open flue gas full heat recovery system according to claim 1 is characterized in that: The first evaporator (13) is a finned tube evaporator, and the first evaporator (13) is provided with a fan for performing forced convection heat exchange with air in the environment.

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