Air compression-heating combined system based on absorption heat pump pre-cooling

Abstract

The application discloses an air compression-heat supply combined system based on absorption heat pump precooling, and specifically comprises a generator, a condenser, an evaporator, an absorber, an air compressor, a throttle valve, a solution heat exchanger, a pressure reducing valve, a solution pump, a three-way valve, a low-temperature heat exchanger, a chilled water pump, a water separator, a water storage tank and a high-temperature heat exchanger. The high-temperature air outlet of the air compressor is connected with the generator of the absorption heat pump, the high-temperature exhaust waste heat of the air compressor is used as the driving heat source of the absorption heat pump, the low-temperature chilled water prepared by the evaporator of the absorption heat pump is used for precooling and temperature reduction of the air entering the air compressor, the compression power consumption of the air compressor can be effectively reduced, the precooling process does not need additional energy consumption except for a small amount of pump consumption, and the energy-saving effect is remarkable. Meanwhile, the absorber and the condenser of the absorption heat pump release medium-temperature heat to heat the heat network water for heat supply. The application realizes the double effects of precooling air for reducing compression power consumption and waste heat cascade utilization for heat supply.

Description

Technical Field

[0001] This invention relates to an air compression-heating combined system based on absorption heat pump precooling. Background Technology

[0002] Air compressors are widely used in various fields of industrial production, including gas transportation, gas synthesis and polymerization, refrigeration, and gas separation. They also serve as power sources for pneumatic equipment. Statistics show that compressed air systems account for 10% to 20% of total electricity consumption in industrial plants, with 90% of this coming from air compressors. Therefore, implementing energy-saving measures for air compressors can effectively reduce electricity consumption in industrial production. The compression process of an air compressor generates a large amount of heat, resulting in very high exhaust temperatures. One energy-saving method is waste heat recovery from the high-temperature exhaust, such as the "Technical Method for Waste Heat Recovery and Utilization of Air Compressors" disclosed in CN202310160263.8. Another energy-saving approach for air compressors is to cool the compressed air based on thermodynamic theory; this cooling process can be carried out at different stages. For example, cooling throughout the entire compression process achieves a near-isothermal compression effect, resulting in significantly lower compression power consumption compared to adiabatic compression, as disclosed in CN202211201460.1, "A Two-Stage Compression Permanent Magnet Variable Frequency Screw Air Compressor." Another cooling method involves interstage cooling during multi-stage compression, as disclosed in CN202222220161.4, "A Multi-Stage Compression Air Compressor." Both of these cooling methods place specific requirements on the air compressor structure. A third cooling method is applicable to any air compressor, requiring only pre-cooling of the inlet air, as disclosed in CN202022123974.2, "A Compressed Air Inlet Cooling and Exhaust Dehumidification Energy-Saving Device." According to the second law of thermodynamics, cooling below ambient temperature cannot be spontaneously obtained and requires additional energy consumption, typically using an electric compressor. In summary, existing technologies, on the one hand, impose specific requirements on the air compressor structure, lacking universality; on the other hand, they incur corresponding energy costs, such as electrical energy consumption, resulting in less than ideal overall energy-saving effects. Summary of the Invention

[0003] This invention provides an air compression-heating combined system based on absorption heat pump precooling. It combines air compressor intake precooling and exhaust waste heat recovery through absorption heat pump, making full use of the cooling and heating loads of each component and rationally allocating the comprehensive cooling / heating needs. This reduces the energy consumption of the air compressor system to the greatest extent, reduces the energy cost of reducing energy consumption, and improves the energy-saving effect of existing technologies.

[0004] The objective of this invention is achieved through the following technical solution. An air compression-heating combined system based on absorption heat pump precooling includes: a generator, a condenser, an evaporator, an absorber, an air compressor, a throttling valve, a solution heat exchanger, a pressure reducing valve, a solution pump, a three-way valve, a low-temperature heat exchanger, a chilled water pump, a water separator, a water storage tank, and a high-temperature heat exchanger.

[0005] According to one embodiment of the present invention, the air entering the compressor is pre-cooled to save power consumption during the compression process. The ambient air is pre-cooled by chilled water in a low-temperature heat exchanger, and after being dehydrated by a water separator, it enters the air compressor to generate high-temperature, high-pressure compressed air. Chilled water generated in the evaporator partially enters the low-temperature heat exchanger after passing through a three-way valve, and ambient air is also introduced into the low-temperature heat exchanger. After being heated by heat exchange in the low-temperature heat exchanger, the chilled water enters a water storage tank, and is then pumped by a chilled water pump to the evaporator for cooling, completing the chilled water circulation.

[0006] According to one embodiment of the present invention, compressed air enters the generator to drive the absorption heat pump to work, and at the same time the temperature drops, and then enters the high-temperature heat exchanger to heat the heating network water; the heating network water passes through the absorber, condenser and high-temperature heat exchanger in sequence and is heated in stages before being sent to the heat users.

[0007] According to one embodiment of the present invention, the high-temperature air discharged from the air compressor heats the solution in the generator, driving the absorption heat pump for refrigeration; water vapor is generated by evaporation in the generator, increasing the solution concentration, and the water vapor enters the condenser to condense, releasing heat to heat the heating network water; the condensate enters the evaporator through the throttling valve, is heated and evaporated into gas, and enters the absorber; the solution in the absorber absorbs water vapor, decreasing the solution concentration, and the dilute solution generated during the absorption process is pumped to the solution heat exchanger to exchange heat with the concentrated solution generated during the generation process, and after being heated, it enters the generator; at the same time, the concentrated solution is cooled, and then after being depressurized by the pressure reducing valve, it enters the absorber, completing the absorption refrigeration cycle.

[0008] According to one embodiment of the present invention, the air from the environment is pre-cooled and its temperature decreases, causing condensation. In order to avoid damage to the internal blades of the air compressor caused by the impact of condensation droplets, the pre-cooled air is dehydrated by a water separator before entering the air compressor.

[0009] According to one embodiment of the present invention, for different operating conditions, the air inlet of the air compressor needs to be reduced to a specific temperature. The flow rate of chilled water entering the low-temperature heat exchanger for heat exchange is controlled by the opening of a three-way valve. When a lower temperature needs to be reached or the amount of air from the environment is large, the opening of the three-way valve is increased. When a smaller temperature reduction is needed or the amount of air from the environment is small, the opening of the three-way valve is decreased.

[0010] The beneficial effects of this invention include:

[0011] The absorption heat pump pre-cooled air compression-heating combined system combines the pre-cooling of the air compressor intake air with the recovery of exhaust waste heat through the absorption heat pump. It makes full use of the heating and cooling loads of each component and rationally allocates the overall cooling / heating needs. While pre-cooling the air entering the air compressor, it uses the absorber and condenser of the absorption heat pump to release heat, as well as the waste heat of the compressed air after passing through the generator, to heat the heating network water, thus achieving waste heat recovery. Furthermore, the heat exchange flow rate can be adjusted through a three-way valve, making it suitable for air compressor inlet air cooling needs under various operating conditions. Apart from a small amount of pumping power consumption, there is no additional power consumption, requiring no additional energy, resulting in excellent energy-saving performance. Attached Figure Description

[0012] Figure 1 This invention proposes an air compression-heating combined system based on absorption heat pump precooling.

[0013] Explanation of reference numerals in the attached figures:

[0014] 1-Generator, 2-Condenser, 3-Evaporator, 4-Absorber, 5-Air compressor, 6-Throttle valve, 7-Heat exchanger, 8-Pressure reducing valve, 9-Solution pump, 10-Three-way valve, 11-Low-temperature heat exchanger, 12-Chilled water pump, 13-Water separator, 14-Water storage tank, 15-High-temperature heat exchanger. Detailed Implementation

[0015] The technical solution of this patent will be further explained below with reference to specific embodiments.

[0016] This invention proposes an air compression-heating combined system based on absorption heat pump precooling. By combining the precooling of the air compressor intake and the recovery of exhaust waste heat through the absorption heat pump, the low-temperature chilled water generated by the evaporator in the absorption heat pump is used to precool the air at the air compressor intake, thereby reducing compression power consumption. The heat released by the absorber and condenser of the absorption heat pump, as well as the waste heat of the compressed air after passing through the generator, is used to heat the heating network water, thereby realizing waste heat utilization for heating.

[0017] like Figure 1 As shown, an air compression-heating combined system based on absorption heat pump precooling according to an embodiment of the present invention includes a generator 1, a condenser 2, an evaporator 3, an absorber 4, an air compressor 5, a throttle valve 6, a heat exchanger 7, a pressure reducing valve 8, a solution pump 9, a three-way valve 10, a low-temperature heat exchanger 11, a chilled water pump 12, a water separator 13, a water storage tank 14, and a high-temperature heat exchanger 15, wherein:

[0018] Air from the environment first enters the low-temperature heat exchanger 11 for pre-cooling, and then passes through the water separator 13 to remove water. The resulting low-temperature dry air is then sent to the air compressor 5, thereby saving compression work and avoiding the impact of the condensate precipitated during cooling on the blades of the air compressor 5.

[0019] The high-temperature air discharged from the air compressor 5 is fed into the generator 1 to heat the solution therein, causing the solution in the generator 1 to evaporate and produce water vapor. This water vapor enters the condenser 2 and condenses. The resulting condensate enters the evaporator 3 through the throttling valve 6, where it is heated and evaporated into gas, which then enters the absorber 4. The solution in the absorber 4 absorbs the water vapor. The dilute solution produced during the absorption process is pumped by the solution pump 9 to the heat exchanger 7, where it exchanges heat with the concentrated solution produced during the generation process before entering the generator 1. Simultaneously, the concentrated solution is depressurized by the pressure reducing valve 8 before entering the absorber 4, completing the absorption refrigeration cycle.

[0020] The chilled water produced by evaporator 3 is fed into a three-way valve 10, which splits it into two paths. One path enters the low-temperature heat exchanger 11 to participate in heat exchange, while the other path bypasses it. The two paths merge before entering the water storage tank 14. Adjusting the opening of the three-way valve 10 can control the flow rate of the chilled water participating in heat exchange, thereby controlling the inlet air temperature of the air compressor.

[0021] After being heated in two stages by the condenser 2 and the absorber 4, the hot water in the heating network exchanges heat again with the compressed air that has been cooled after passing through the generator 1 in the high-temperature heat exchanger 15, thus achieving three-stage heating.

[0022] The water side and air side of the high-temperature heat exchanger 15 are arranged in counter-current flow, which can improve the heat exchange efficiency.

[0023] After passing through the low-temperature heat exchanger 11, the chilled water is introduced into the water storage tank 14 to mix with the existing stored water and cool down. Then, the chilled water pump 12 pumps the water from the water storage tank 14 to the evaporator 3 to complete the chilled water circulation.

[0024] Beneficial effects or advantages include:

[0025] 1) This invention is based on an air compression-heating combined system using absorption heat pump precooling. A portion of the chilled water generated by the absorption heat pump, after passing through a three-way valve, is used to precool the external air entering the air compressor. The flow rate of the chilled water participating in heat exchange is adjusted to produce different cooling effects, achieving the goal of saving a significant amount of compression power at the expense of a small amount of pumping power. After the external air is precooled, a water separator is added to remove the condensate generated during cooling, preventing the condensate from impacting and damaging the air compressor blades.

[0026] 2) In the air compression-heating combined system based on absorption heat pump precooling according to the present invention, the heat network water is heated in three stages by the waste heat of the absorber, condenser and high temperature heat exchanger and then used for heating. The hot and cold ends of the high temperature heat exchanger are arranged in countercurrent, realizing efficient recovery and utilization of waste heat.

[0027] 3) The air compression-heating combined system based on absorption heat pump precooling according to the present invention has a simple structure. By utilizing the absorption heat pump, low-grade heat sources can be used, which improves the energy-saving and environmental protection effect. It also makes flexible use of the cooling and heating loads of each component and rationally allocates them according to the cooling / heating requirements, thereby minimizing energy consumption.

[0028] 4) The air compression-heating combined system based on absorption heat pump precooling according to the present invention has no limitation on the structure of the air compressor, and various existing air compressors can use the combined system.

Claims

1. An air compression-heating combined system based on absorption heat pump precooling, characterized in that... include: Generator (1), condenser (2), evaporator (3), absorber (4), air compressor (5), throttle valve (6), heat exchanger (7), pressure reducing valve (8), solution pump (9), three-way valve (10), low temperature heat exchanger (11), chilled water pump (12), water separator (13), water storage tank (14), high temperature heat exchanger (15). in: Air from the environment is pre-cooled by chilled water in a low-temperature heat exchanger (11), and after passing through a water separator (13), it enters the air compressor (5) and is compressed into compressed air at high temperature and high pressure. High-temperature and high-pressure compressed air enters the generator (1), drives the solution inside the generator (1) to generate water vapor through evaporation, and at the same time the temperature of the compressed air drops, and then enters the high-temperature heat exchanger (15) to heat the hot water network. The compressed air is further cooled down and then discharged. The hot water in the heating network passes sequentially through the absorber (4), condenser (2), and high-temperature heat exchanger (15), and is heated in stages. The water vapor enters the condenser (2) and condenses. The resulting condensate enters the evaporator (3) through the throttling valve (6) and is heated and evaporated into gas, which then enters the absorber (4). The solution in the absorber (4) absorbs water vapor. The dilute solution produced during the absorption process is pumped by the solution pump (9) to the heat exchanger (7), where it exchanges heat with the concentrated solution produced during the generation process and then enters the generator (1). At the same time, the concentrated solution is depressurized by the pressure reducing valve (8) and then enters the absorber (4), thus completing the absorption refrigeration cycle. The chilled water produced by the evaporator (3) is divided into two paths through a three-way valve (10). The first path enters the low-temperature heat exchanger (11) to participate in heat exchange, while the second path bypasses it. The first and second paths merge before entering the water storage tank (14). By adjusting the opening of the three-way valve (10), the flow rate of the chilled water participating in heat exchange is controlled, thereby controlling the inlet air temperature of the air compressor. After being heated in two stages by the condenser (2) and absorber (4), the hot water in the heating network exchanges heat again with the compressed air that has been cooled after passing through the generator (1) in the high-temperature heat exchanger (15), thus achieving a third stage of heating. After passing through the low-temperature heat exchanger (11), the chilled water is introduced into the storage tank (14) to mix with the existing stored water and cool down. Then, the chilled water is pumped from the storage tank (14) to the evaporator (3) by the chilled water pump (12) to complete the chilled water circulation. The air inlet of the air compressor (5) is pre-cooled, and the cooling capacity required for this pre-cooling comes from an absorption heat pump. Absorption heat pumps are driven by the high-temperature waste heat of the air outlet of the air compressor (5).

2. The air compression-heating combined system based on absorption heat pump precooling according to claim 1, characterized in that: After the air from the environment is pre-cooled by the chilled water, condensate will be generated. The water separator (13) separates the condensate from the air to ensure that the air entering the air compressor (5) is dry and to prevent droplets from hitting the blades inside the air compressor (5) and causing blade damage.

3. The air compression-heating combined system based on absorption heat pump precooling according to claim 1, characterized in that: The discharged compressed air is sent to the required process stage.

4. The air compression-heating combined system based on absorption heat pump precooling according to claim 1, characterized in that: The hot water passes through the absorber (4), condenser (2), and high-temperature heat exchanger (15) in sequence, and is heated to the temperature required for heating in stages, and is finally sent to the heat users.

5. The air compression-heating combined system based on absorption heat pump precooling according to claim 1, characterized in that: The water side and air side of the high-temperature heat exchanger (15) are arranged in counter-current flow.

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