High-temperature steam heat pump condensation system based on flash tank water replenishing and preheating

Abstract

The invention discloses a high-temperature steam heat pump condensation system based on flash tank replenished water preheating, which comprises a heat pump circulation module, a replenished water preheating module and a flash module, the heat pump circulation module comprises a compressor, a condenser, a plate heat exchanger, an expansion valve and an evaporator; the water replenishing and preheating module comprises a water replenishing pipe and a water replenishing pump; and the flash evaporation module comprises a flash evaporation tank, a regulating valve and a steam outlet. The plate heat exchanger and the condenser are arranged, the plate heat exchanger is used for recycling supercooling degree heat of a refrigerant, supplemented water can be preheated, and therefore the heating load of the condenser is reduced; after the preheated replenished water enters the condenser, the process of heating to the saturation temperature is more uniform, formation of a local low-temperature area is avoided, meanwhile, gradient utilization of energy is achieved in the water replenishing process, and the heat efficiency of the system is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial waste heat recovery and high-temperature heat pump technology, and in particular to a high-temperature steam heat pump condensing system based on flash tank water preheating. Background Art

[0002] In industrial production, high-temperature steam is widely used as an important energy carrier in heating, drying, sterilization, and other process steps. Flash high-temperature steam heat pump systems consume a small amount of high-quality electricity to drive low-grade waste heat (such as industrial wastewater, exhaust gas, and exhaust steam) into high-temperature steam. This system offers significant energy-saving advantages and is a key technology for achieving the "dual carbon" goals.

[0003] As the core equipment of the system, the flash tank requires continuous replenishment of softened water to maintain liquid level balance and steam production. In traditional systems, low-temperature feed water enters the condenser directly, where it absorbs the refrigerant's heat of condensation and heats up to near saturation before entering the flash tank. This design has the following significant drawbacks: A surge in the condenser's heat load: When the low-temperature feed water directly exchanges heat with the high-temperature refrigerant, it absorbs a large amount of latent heat, increasing the condenser's heat load and reducing the system's energy efficiency. Summary of the Invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a high-temperature steam heat pump condensing system based on flash tank water preheating.

[0005] In order to achieve the above-mentioned object, the present invention adopts the following technical scheme: a high-temperature steam heat pump condensing system based on flash tank water preheating, comprising a heat pump circulation module, a water preheating module and a flash evaporation module, the heat pump circulation module comprising a compressor, a condenser, a plate heat exchanger, an expansion valve and an evaporator, the output end of the compressor is fixedly connected to an exhaust pipe, the end of the exhaust pipe away from the compressor is connected to the input end of the condenser, the output end of the condenser is fixedly connected to the input end of the plate heat exchanger through a pipeline, the output end of the plate heat exchanger is fixedly connected to the input end of the expansion valve through a heating liquid pipe, the output end of the expansion valve is fixedly connected to the input end of the evaporator through a pipeline, and the output end of the evaporator is fixedly connected to the input end of the compressor through a return air pipe;

[0006] The water supply and preheating module includes a water supply pipe and a water supply pump. The input end of the plate heat exchanger is fixedly connected to the water supply pipe, and the water supply pipe is fixedly connected to the water supply pump.

[0007] The flash module includes a flash tank, a regulating valve and a steam outlet. The output end of the condenser is fixedly connected to the input end of the flash tank through a pipeline. The gas outlet end of the flash tank is fixedly connected to the regulating valve through a pipeline. The output end of the regulating valve is fixedly connected to the steam outlet.

[0008] As a further description of the above technical solutions:

[0009] The water outlet end of the flash tank is fixedly connected with the backwater pipe and the water supplement pipe.

[0010] As a further description of the above technical solutions:

[0011] The plate heat exchanger is a brazed plate heat exchanger, and the plate heat exchanger is provided with a first medium channel and a second medium channel; the first medium channel is a refrigerant channel, the inlet of the first medium channel is fixedly communicated with the outlet of the condenser, and the outlet of the first medium channel is communicated with the expansion valve; the second medium channel is a water supplement channel, and the inlet of the second medium channel is communicated with the water supplement pipe.

[0012] As a further description of the above technical solutions:

[0013] The condenser is a shell-and-tube heat exchanger composed of a shell side and a tube side; the shell side is a refrigerant condensing channel, the inlet of the shell side is communicated with the exhaust pipe, the outlet of the shell side is communicated with the inlet of the first medium channel through a pipeline, and the tube side is a water supplement heating channel; the inlet of the tube side is communicated with the outlet of the second medium channel, and the outlet of the tube side is communicated with the feeding port of the flash tank.

[0014] As a further description of the above technical solutions:

[0015] The side end of the evaporator is provided with a heat source inlet and a heat source outlet, and the heat source inlet is communicated with the industrial waste gas pipeline.

[0016] As a further description of the above technical solutions:

[0017] The water supplement pipe is fixedly connected with a circulating water pump.

[0018] The present application has the following beneficial effects:

[0019] Compared with the prior art, the plate heat exchanger and the condenser are arranged, the refrigerant supercooling degree heat is recovered by using the plate heat exchanger, the water supplement can be preheated, so that the heating load of the condenser is reduced; after the preheated water supplement enters the condenser, the process of rising to the saturation temperature is more uniform, the formation of a local low-temperature area is avoided, and the energy cascade utilization is realized in the process of water supplement, so that the system thermal efficiency is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A flow chart of a high-temperature steam heat pump condensing system based on flash tank water supplement preheating is provided.

[0021] LEGEND:

[0022] 1. Compressor; 2. Exhaust pipe; 3. Condenser; 4. Plate heat exchanger; 5. Heating liquid pipe; 6. Expansion valve; 7. Evaporator; 8. Return air pipe; 9. Make-up water pipe; 10. Make-up water pump; 11. Circulating water pump; 12. Flash tank; 13. Control valve; 14. Steam outlet; 15. Return water pipe. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Reference Figure 1The present invention provides a high-temperature steam heat pump condensing system based on flash tank water preheating, which includes a heat pump circulation module, a water preheating module and a flash evaporation module. The heat pump circulation module includes a compressor 1, a condenser 3, a plate heat exchanger 4, an expansion valve 6 and an evaporator 7. The output end of the compressor 1 is fixedly connected to an exhaust pipe 2. The end of the exhaust pipe 2 away from the compressor 1 is connected to the input end of the condenser 3. The output end of the condenser 3 is fixedly connected to the input end of the plate heat exchanger 4 through a pipeline. The output end of the plate heat exchanger 4 is connected to the heating liquid pipe through the heating liquid pipe. 5 is fixedly connected to the input end of the expansion valve 6, the output end of the expansion valve 6 is fixedly connected to the input end of the evaporator 7 through a pipeline, and the output end of the evaporator 7 is fixedly connected to the input end of the compressor 1 through the return air pipe 8; the plate heat exchanger 4 is a brazed plate heat exchanger, and a first medium channel and a second medium channel are provided in the plate heat exchanger 4. The first medium channel is a refrigerant channel, the inlet of the first medium channel is fixedly connected to the output end of the condenser 3, and the outlet of the first medium channel is connected to the expansion valve 6; the second medium channel is a water supply channel, and the second medium channel is a refrigerant channel. The inlet of the channel is connected to the water supply pipe 9; the condenser 3 is a shell and tube heat exchanger composed of a shell side and a tube side, the shell side is a refrigerant condensation channel, the inlet of the shell side is connected to the exhaust pipe 2, the outlet of the shell side is connected to the inlet of the first medium channel through a pipeline, the tube side is a water supply heating channel, the inlet of the tube side is connected to the outlet of the second medium channel, and the outlet of the tube side is connected to the feed port of the flash tank 12; a heat source inlet and a heat source outlet are provided at the side end of the evaporator 7, and the heat source inlet is connected to the industrial waste gas pipeline; the water supply preheating module includes a water supply pipe 9 and a water supply pump 10 The input end of the plate heat exchanger 4 is fixedly connected to a water supply pipe 9, to which a water supply pump 10 is fixedly connected; the water supply pipe 9 is fixedly connected to a circulating water pump 11; the flash module includes a flash tank 12, a regulating valve 13 and a steam outlet 14, the output end of the condenser 3 is fixedly connected to the input end of the flash tank 12 through a pipeline, the gas outlet end of the flash tank 12 is fixedly connected to the regulating valve 13 through a pipeline, and the output end of the regulating valve 13 is fixedly connected to the steam outlet 14; the water outlet end of the flash tank 12 is fixedly connected to the water supply pipe 9 through a return pipe 15.

[0025] When in use, the heat pump cycles:

[0026] Compressor 1 compresses the refrigerant into high-temperature, high-pressure steam at 200°C and 2.5 MPa, which enters the shell side of condenser 3 through exhaust pipe 2. The refrigerant condenses into liquid in condenser 3, with the temperature dropping to 190°C, and then flows into the first medium channel of plate heat exchanger 4. The refrigerant is further cooled to 170°C in plate heat exchanger 4, throttled by expansion valve 6, enters evaporator 7, absorbs waste heat, evaporates into steam, and returns to compressor 1 through return pipe 8, completing the cycle.

[0027] Water preheating and heating:

[0028] The normal temperature make-up water of 20°C is treated by the softening water processor, pressurized to 0.8 MPa by the make-up water pump 10, and sent to the second medium channel of the plate heat exchanger 4 through the circulating water pump 11; in the plate heat exchanger 4, the make-up water and the refrigerant at 190°C are countercurrently exchanged and the temperature is raised to 110°C; the preheated make-up water enters the tube side of the condenser 3 and exchanges heat with the shell side refrigerant at 200°C to 175°C, and then enters the flash tank 12.

[0029] Flash process:

[0030] High-temperature water at 175°C enters the flash tank 12. Because the water temperature is higher than the saturation temperature, part of the water flashes into steam; the steam is output at a stable pressure through the regulating valve 13; the saturated water at 165°C at the bottom of the flash tank 12 flows back into the water supply pipe 9 through the return pipe 15, and then flows back to the condenser 3 through the plate heat exchanger 4 under the action of the circulating water pump 11 to be reheated to maintain a stable liquid level.

[0031] The specific operation method is as follows:

[0032] 1. High-temperature refrigerant flow: The high-temperature and high-pressure refrigerant discharged from the compressor 1 enters the condenser 3 through the exhaust pipe 2. After heat exchange with the preheated make-up water entering the condenser 3, it forms a high-temperature refrigerant liquid with a temperature of T1 (190°C) and flows into the first medium channel of the plate heat exchanger 4.

[0033] 2. Low-temperature make-up water preheating: The low-temperature make-up water temperature T0 (20°C) from the make-up water pipe 9 is sent to the second medium channel of the plate heat exchanger 4 through the make-up water pump 10 and the circulating water pump 11, and performs countercurrent heat exchange with the high-temperature refrigerant liquid in the first medium channel. After absorbing heat, the temperature is raised to T3 (110°C), forming preheated make-up water;

[0034] 3. Make-up water reheating: The preheated make-up water flows out of the plate heat exchanger 4 and enters the make-up water inlet of the condenser 3, where it further exchanges heat with the high-temperature refrigerant in the condenser 3 and is heated to T4 (175°C);

[0035] 4. Flash evaporation process: High-temperature water with a temperature of T4 enters the flash evaporation tank 12. Under the environment below its saturation pressure in the tank, part of the water flashes into steam and is output to the user end through the regulating valve 13. The remaining saturated water is recycled or output as high-temperature hot water;

[0036] 5. Refrigerant circulation: After releasing heat in the first medium channel of the plate heat exchanger 4, the refrigerant temperature T2 (170°C) enters the evaporator 7 after passing through the heating liquid pipe 5 and the expansion valve 6 for throttling and pressure reduction. After absorbing heat from the heat source side, it evaporates into gas and returns to the compressor 1 through the return pipe 8, completing the heat pump cycle.

[0037] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-temperature steam heat pump condensing system based on flash tank water preheating, characterized by: The invention comprises a heat pump circulation module, a water replenishment preheating module and a flash evaporation module, wherein the heat pump circulation module comprises a compressor (1), a condenser (3), a plate heat exchanger (4), an expansion valve (6) and an evaporator (7); the output end of the compressor (1) is fixedly connected to an exhaust pipe (2); the end of the exhaust pipe (2) away from the compressor (1) is connected to the input end of the condenser (3); the output end of the condenser (3) is fixedly connected to the input end of the plate heat exchanger (4) through a pipe; the output end of the plate heat exchanger (4) is fixedly connected to the input end of the expansion valve (6) through a heating liquid pipe (5); the output end of the expansion valve (6) is fixedly connected to the input end of the evaporator (7) through a pipe; and the output end of the evaporator (7) is fixedly connected to the input end of the compressor (1) through a return air pipe (8); The water supply preheating module comprises a water supply pipe (9) and a water supply pump (10); the input end of the plate heat exchanger (4) is fixedly connected to the water supply pipe (9), and the water supply pump (10) is fixedly connected to the water supply pipe (9); The flash module comprises a flash tank (12), a regulating valve (13) and a steam outlet (14); the output end of the condenser (3) is fixedly connected to the input end of the flash tank (12) via a pipeline; the gas outlet end of the flash tank (12) is fixedly connected to the regulating valve (13) via a pipeline; and the output end of the regulating valve (13) is fixedly connected to the steam outlet (14).

2. A high-temperature steam heat pump condensing system based on flash tank water preheating according to claim 1, characterized in that: The water outlet end of the flash tank (12) is fixedly connected to the water supply pipe (9) via a return pipe (15).

3. The high-temperature steam heat pump condensing system based on flash tank water preheating according to claim 1 is characterized in that: The plate heat exchanger (4) is a brazed plate heat exchanger, and a first medium channel and a second medium channel are provided in the plate heat exchanger (4). The first medium channel is a refrigerant channel, the inlet of the first medium channel is fixedly connected to the output end of the condenser (3), and the outlet of the first medium channel is connected to the expansion valve (6); the second medium channel is a water supply channel, and the inlet of the second medium channel is connected to the water supply pipe (9).

4. A high-temperature steam heat pump condensing system based on flash tank water preheating according to claim 3, characterized in that: The condenser (3) is a shell-and-tube heat exchanger consisting of a shell side and a tube side. The shell side is a refrigerant condensation channel. The inlet of the shell side is connected to the exhaust pipe (2). The outlet of the shell side is connected to the inlet of the first medium channel through a pipeline. The tube side is a water replenishment heating channel. The inlet of the tube side is connected to the outlet of the second medium channel. The outlet of the tube side is connected to the feed port of the flash tank (12).

5. The high-temperature steam heat pump condensing system based on flash tank water preheating according to claim 1 is characterized in that: A heat source inlet and a heat source outlet are provided at the side end of the evaporator (7), and the heat source inlet is communicated with the industrial waste gas pipeline.

6. The high-temperature steam heat pump condensing system based on flash tank water preheating according to claim 1, characterized in that: A circulating water pump (11) is fixedly connected to the water supply pipe (9).

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