CN113686051B - Open type compression absorption heat pump system for recovering water heat in high-temperature and high-humidity gas - Google Patents

Open type compression absorption heat pump system for recovering water heat in high-temperature and high-humidity gas Download PDF

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CN113686051B
CN113686051B CN202110935873.1A CN202110935873A CN113686051B CN 113686051 B CN113686051 B CN 113686051B CN 202110935873 A CN202110935873 A CN 202110935873A CN 113686051 B CN113686051 B CN 113686051B
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solution
gas
heat exchanger
heat
pressure
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CN113686051A (en
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董勇
王晓哲
崔琳
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Shandong University
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Shandong University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B30/00—Heat pumps
    • F25B30/04—Heat pumps of the sorption type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B30/00—Heat pumps
    • F25B30/06—Heat pumps characterised by the source of low potential heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation
    • Y02A30/27—Relating to heating, ventilation or air conditioning [HVAC] technologies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/52—Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/62—Absorption based systems

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Sorption Type Refrigeration Machines (AREA)
  • Drying Of Gases (AREA)

Abstract

The invention provides an open compression absorption heat pump system for recovering water heat in high-temperature and high-humidity gas, wherein an outlet of a gas pipeline is connected with a contact type heat exchanger, a gas pressure adjusting device is arranged on the gas pipeline, the contact type heat exchanger is connected with an absorber, a gas outlet at the upper end of the absorber is connected with an expander, and a first pressure control valve is arranged on a pipeline between the absorber and the expander; the system comprises a circulating water inlet, a solution-water heat exchanger, a condenser, a contact heat exchanger, a circulating water tank, a user-side heat output device and a user-side heat output device, wherein the circulating water inlet is connected with the solution-water heat exchanger; the absorber is connected with a solution heat exchanger, the solution heat exchanger is connected with a regenerator, the regenerator is connected with a solution heat exchanger, the solution heat exchanger is connected with a solution water heat exchanger, and the solution water heat exchanger is connected with the absorber; the regenerator is connected with a condenser, and the condenser is connected with a vacuum pump; the expander delivers energy to a vacuum pump. The invention can further realize the utilization of the waste heat of the high-temperature and high-humidity gas, the recovery of water, the capture of pollutant components and the recycling of gas expansion work, and has extremely strong engineering practice significance.

Description

Open type compression absorption heat pump system for recovering water heat in high-temperature and high-humidity gas
Technical Field
The invention belongs to the technical field of heat exchange, waste heat utilization and environmental protection, and relates to an open compression absorption heat pump system for recovering water heat in high-temperature and high-humidity gas.
Background
High-temperature and high-humidity gas is widely existed in various industrial industries, and comprises high-temperature and high-humidity air, desulfurized flue gas, high-humidity gas and the like. Taking a coal-fired boiler of 600MW as an example, the water vapor content in the discharged wet flue gas is about 230t/h, which causes the discharge loss of a large amount of water resources. Meanwhile, the water vapor fog drops form a condensation core when being discharged, and the formation of the haze can be promoted under certain meteorological conditions. On the other hand, the flue gas at 50 ℃ is used as waste heat, although the energy quality and the taste are low and the density is low, the total amount is large, and the direct discharge to the environment causes heat loss. Therefore, the method has double meanings of saving energy and protecting the environment for recycling the moisture and the waste heat of the high-temperature and high-humidity gas.
The heat pump is a common technology for improving energy quality and utilizing the energy, adopts reverse Carnot cycle to transfer heat from a low-temperature heat source to a high-temperature heat source, and is widely applied to industries such as circulating water waste heat of a power plant, printing and dyeing, pharmacy and the like. Compression heat pumps and absorption heat pumps are common. A conventional compression heat pump consists of an evaporator, a compressor, a condenser and an expansion valve. The working medium absorbs the heat of the low-temperature heat source in the evaporator and then evaporates, then enters the compressor, the compressor compresses the working medium steam into the high-temperature high-pressure working medium and then enters the condenser, the working medium is condensed in the condenser to release heat, and finally the working medium is sent into the evaporator after passing through the expansion valve to complete a cycle, so that the heat of the low-temperature heat source is transferred to the medium-high temperature heat source. The traditional absorption heat pump consists of an absorber, a throttle valve, a regenerator, a condenser, an evaporator and the like. The absorption solution is heated in the generator, a refrigerant in the solution is boiled and evaporated firstly, is condensed into liquid in the regenerative steam condenser, releases heat on the surface of the regenerative steam condenser, absorbs the heat of a low-temperature heat source in the evaporator through the throttling and pressure reducing effects of the throttling device to evaporate, and the refrigerant is in a low-pressure steam state; the high-concentration absorbent remained in the process is conveyed into the absorber through the solution pump, mixed with low-pressure steam from the evaporator and absorbed, so that the absorbent is restored to the original concentration. Because the specific heat of the gas is low, the traditional indirect heat exchange process is adopted in the heat pump to utilize the waste heat of the high-temperature high-humidity gas, the waste heat is influenced by the cold end temperature difference between the gas and the heat absorbing medium, the heat exchange amount is small, the outlet temperature of the heat absorbing medium is low and is generally lower than the gas outlet temperature of the heat exchanger by about 5 ℃, and the outlet temperature is low, so that the subsequent heat utilization scene is limited; meanwhile, the gas can only be cooled to the dew point temperature in an indirect heat exchange mode, a large amount of latent heat of vaporization and moisture in the gas cannot be utilized, and the waste heat utilization effect is poor.
In recent years, there has been much research and development on compression heat pumps, such as patents: the high-temperature heat source is adopted as the drive in the first type of thermally driven compression heat pump (CN 201810685634.3), the second type of thermally driven compression heat pump (CN 201610815260.3), the third type of thermally driven compression heat pump (CN 201810685635.8) and the fourth type of thermally driven compression heat pump (CN 202010252741.4), so that the output of heat supply and mechanical energy is realized. Wherein, low temperature heat medium and working medium adopt indirect contact's traditional heat transfer form, and the holistic heat transfer effect of two kinds of medium cold junction difference in the heat transfer process, this type of heat pump if utilize high temperature and high humidity gas as low temperature heat medium, will only utilize the partial energy of sensible heat of gas, can't realize extracting and utilizing steam and latent heat thereof. Such as the patent: an open type absorption heat pump-MVR technology coupled closed cycle drying system (CN 202010720409.6) and an open type heat pump device driven by high-temperature flue gas and application thereof (CN 202011257645.5) adopt an open type heat pump mode, a flue gas heat source is used as a low-temperature heat source, electric energy or superheated steam is used as a high-temperature heat source, and the heat pump is used for upgrading and heating, so that the utilization of waste heat is realized. The absorption heat pump is limited by the crystallization temperature of the absorption solution, and the solution temperature needs to be below the crystallization temperature of the corresponding concentration, so that the working range of the solution of the absorption heat pump is limited.
The applicant's prior application "a wet flue gas source heat pump system for controlling input flue gas pressure" (CN 202110363262.4) has carried out research in relevant aspects, and the application provides a novel wet flue gas source heat pump for collecting water, recovering waste heat and removing pollutants, wherein after the flue gas pressure is increased, the temperature of wet flue gas is increased, and then the wet flue gas is subjected to direct contact type heat exchange with circulating water, wherein the flue gas is cooled to release sensible heat, and after the water vapor in the flue gas reaches a saturated state, the latent heat of vaporization is further released. And after the heated circulating water enters the user side heat output device to output heat, the circulating water is cooled and enters the heat exchanger to be sprayed to complete circulation. In the operation process, the device can utilize the latent heat of vaporization of water vapor in wet flue gas, the flue gas at an outlet is in a positive pressure state, the dew point temperature of the flue gas is increased, and the water vapor can be condensed in a saturated state more easily. Meanwhile, the moisture content of the flue gas is reduced after the pressure of the flue gas is increased, and compared with a common direct contact type condensation mode, more water vapor can be condensed, and more waste heat can be recovered. The cooled saturated wet flue gas enters a turbine, and the turbine impeller is pushed to rotate by virtue of the expansion force in the gas pressure release process, so that a generator is driven to generate electricity or mechanical energy is output to coaxially drive a circulating water pump motor to do work, and finally the exhaust at normal pressure is achieved.
However, the application has the following problems: 1. after the pressurized flue gas is subjected to contact heat exchange, the flue gas is still in a saturated state, and more moisture is still released to the environment, so that the moisture and latent heat of vaporization thereof are wasted; 2. after the heat exchange of the pressurized contact, the temperature of the circulating water is still low, so that the subsequent energy utilization effect is poor; 3. saturated steam directly enters the turbine of the expansion machine, the temperature of the steam is reduced in the pressure relief process, liquid drops are caused to be condensed, the turbine carries water, the power is seriously reduced, and even blades are broken.
Disclosure of Invention
In order to solve the above defects in the prior art, the applicant proposes an open compression absorption heat pump system for recovering water heat from high-temperature and high-humidity gas, wherein the high-temperature and high-humidity gas enters a gas pressure regulating device to increase the gas pressure, then the temperature of the high-temperature and high-humidity gas rises, and then the high-temperature and high-humidity gas and circulating water perform direct contact heat exchange, wherein the gas is cooled to release sensible heat, and the water vapor in the gas further releases latent heat of vaporization after reaching a saturated state. The cooled high-temperature high-humidity air enters the absorber and directly contacts with the absorption solution, the water vapor in the high-temperature high-humidity air is absorbed into the solution to further release latent heat of vaporization, and finally the high-temperature high-humidity air enters the expansion device to release pressure. The circulating water is subjected to indirect heat exchange with the regenerated concentrated solution in the solution water heat exchanger, then subjected to indirect heat exchange with the regenerated steam in the condenser, and then enters the contact heat exchanger to perform contact heat exchange, enters the water tank, is subjected to chemical feeding purification treatment, is conveyed to the user side heat output device to output heat, is cooled, and finally returns to the solution water heat exchanger to complete circulation. The concentrated absorption solution and the cooled high-temperature high-humidity gas generate absorption reaction in the absorber, the water vapor in the high-temperature high-humidity gas enters the absorption solution and simultaneously releases latent heat of vaporization, the concentration of the solution is reduced, the dilute absorption solution exchanges heat with the regenerated concentrated absorption solution in the solution heat exchanger and then enters the regenerator, the regeneration is finished under the action of a certain vacuum degree and a heat source, and the regenerated concentrated solution exchanges heat with circulating water in the solution water heat exchanger and then enters the absorber to be sprayed to finish circulation. The regenerated steam generated in the regeneration process is acted by a vacuum pump, enters the condenser from the regenerator, exchanges heat with circulating water, condensed water enters the condensed water tank, and the residual non-condensable gas is pumped out of the system by the vacuum pump. In the operation process, the device can utilize the latent heat of vaporization of water vapor in high-temperature and high-humidity gas, the outlet flue gas is in a positive pressure state, the dew point temperature of the flue gas is increased, and the water vapor can more easily reach the saturated state for condensation. Meanwhile, the moisture content of the flue gas is reduced after the pressure of the flue gas is increased, and compared with a common direct contact type condensation mode, more water vapor can be condensed, and more waste heat can be recovered. The saturated high-temperature high-humidity gas after temperature reduction enters an absorber, and because the partial pressure of the water vapor in the saturated high-temperature high-humidity gas is higher than the saturated partial pressure of the water vapor on the surface of the absorption solution, the water vapor in the saturated high-temperature high-humidity gas is further absorbed by the absorption solution; finally, the high-temperature and high-humidity gas enters an expansion device, the expansion machine is pushed to do work by means of expansion force in the pressure relief process of the gas, mechanical energy is output, and finally the normal-pressure state is achieved for discharge.
The device is different from the existing closed heat pump system, directly contacts with high-temperature and high-humidity gas through circulating water and absorption solution, recovers latent heat in the high-temperature and high-humidity gas, improves quality and utilizes the latent heat, and is a brand new open heat pump system. The invention adopts the following scheme:
the system comprises a gas pressure adjusting device, a contact type heat exchanger, a pressure control valve, an expander, a heat exchanger, a condensate water tank, an absorber, a regenerator, a vacuum pump, a circulating water tank and a user side heat output device.
An outlet of a gas pipeline is connected with a contact type heat exchanger, a gas pressure adjusting device is arranged on the gas pipeline, the contact type heat exchanger is connected with an absorber, a gas outlet at the upper end of the absorber is connected with an expander, and a first pressure control valve is arranged on a pipeline between the absorber and the expander; the system comprises a circulating water inlet, a solution-water heat exchanger, a condenser, a contact heat exchanger, a circulating water tank, a user-side heat output device and a user-side heat output device, wherein the circulating water inlet is connected with the solution-water heat exchanger; the absorber is connected with the solution heat exchanger, the solution heat exchanger is connected with the regenerator, the regenerator is connected with the solution heat exchanger, the solution heat exchanger is connected with the solution water heat exchanger, and the solution water heat exchanger is connected with the absorber; the regenerator is connected with a condenser, and the condenser is connected with a vacuum pump; the expander delivers energy to a vacuum pump.
High-temperature and high-humidity gas enters the contact type heat exchanger through the outlet of the gas pipeline, heat exchange is carried out between the high-temperature and high-humidity gas and circulating water in the contact type heat exchanger, the gas after heat exchange enters the absorber and exchanges heat with solution in the absorber, and the gas after heat exchange enters the expansion machine to push the expansion machine to do work and output mechanical energy.
Circulating water exchanges heat with gas in the contact heat exchanger, enters the circulating water tank, then enters the user side heat output device from the circulating water tank, enters the solution water heat exchanger after exchanging heat with the user side heat output device, exchanges heat with solution, enters the condenser after exchanging heat, exchanges heat with regenerated steam from the regenerator, and then enters the contact heat exchanger.
The absorption solution enters a solution heat exchanger after undergoing absorption reaction with gas in an absorber, enters a regenerator after exchanging heat with the solution from the regenerator, regenerates in the regenerator, enters a solution water heat exchanger after entering the solution heat exchanger after exchanging heat with the solution, and enters the absorber after exchanging heat with circulating water.
The regeneration steam is generated in the regeneration process of the solution in the regenerator, enters the condenser to exchange heat with the circulating water, and then enters the condensate water tank, and the condensate water tank is connected with the vacuum pump.
Preferably, a circulating water pump I is arranged between the user side heat output device and the solution water heat exchanger, a second pressure control valve is arranged on a pipeline of the circulating water tank and the contact type heat exchanger, and a circulating water pump II is arranged between the circulating water tank and the user side heat output device; a pipeline between the absorber and the solution heat exchanger is provided with a circulating solution pump I, and a pipeline between the regenerator and the solution heat exchanger is provided with a circulating solution pump II.
Preferably, a pipeline connecting the condenser and the condensed water tank extends into the condensed water tank and is submerged in a certain liquid level, a pipeline connecting the condensed water tank and the vacuum pump extends into the condensed water tank, and a pipe orifice is positioned above the liquid level; adopt the low pressure heating evaporation form in the regenerator, regenerator inside sets up heating coil, and absorption solution gets into the regenerator from the top, and the concentrated solution flows out by the regenerator bottom after the regeneration, and the regenerated steam after the regeneration flows out by the regenerator top.
Preferably, the gas pressure regulating means comprises a compressor.
A method for hydrothermal recovery and pollutant removal of high-temperature and high-humidity gas is characterized in that the high-temperature and high-humidity gas enters a gas pressure regulating device through a gas pipeline, is compressed into high-temperature and high-pressure gas, and then is introduced into a contact heat exchanger, the high-temperature and high-pressure gas and circulating water perform direct contact heat exchange, wherein the gas is cooled to release sensible heat, and the water vapor in the gas further releases latent heat of vaporization after reaching a saturated state, so that recovery of the latent heat of vaporization of the gas is realized; circulating water and gas carry out contact heat exchange in a contact heat exchanger, the heated circulating water enters a circulating water tank, after filtration and removal treatment processes, the circulating water is pressurized in a circulating water pump II and then is pumped to a user side heat output device to release heat, the cooled circulating water enters a solution water heat exchanger after being pressurized by a circulating water pump I, the regenerated concentrated solution is cooled, enters a condenser to exchange heat with regenerated steam, and then returns to the contact heat exchanger to spray to complete circulation; the concentrated absorption solution is contacted with high-pressure saturated high-temperature high-humidity gas in an absorber to generate absorption reaction, water vapor enters the solution to reduce the concentration of the solution, the dilute solution is pumped to a solution heat exchanger through a booster pump of a circulating solution pump II to exchange heat with the regenerated concentrated solution, then the regenerated concentrated solution enters a regenerator to be heated and regenerated at low pressure, the regenerated concentrated solution is pumped to the solution heat exchanger through a circulating solution pump I, and then the regenerated concentrated solution enters a solution water heat exchanger to exchange heat with circulating water again and then enters the absorber to be sprayed to finish circulation; the water vapor generated in the regeneration process is driven by the negative pressure generated by the vacuum pump to enter a condensate water tank to remove condensate water, and the residual gas is discharged to the atmospheric environment.
Preferably, the gas pressure in the absorber and the contact heat exchanger is kept the same, which is the sum of the pressurization amount of the gas pressure regulating device and the ambient pressure, and in this embodiment is about 80kPa positive pressure. The temperature was about 45 ℃ at the gas outlet temperature of the heat exchanger. Because the gas pressure after heat exchange is higher than the environmental pressure, the partial pressure of the corresponding water vapor is higher than the partial pressure of the water vapor at the saturation temperature under the corresponding normal pressure state, and the absorption solution can absorb more water vapor under the driving of the partial pressure of the water vapor in the gas and the surface vapor pressure difference of the absorption solution in the absorber; after moisture absorption, the gas can expand to do work in the process of releasing the gas to the environment, so that the expansion work is utilized to drive the turbine of the expansion machine to rotate to do work, and the internal energy of the gas can be converted into a mechanical energy form. The expanded cryogenic gas is discharged to the environment at ambient pressure.
Preferably, the pressure control valve is a self-supporting pressure valve or a digital pressure valve, and is used for controlling the pressure state in the contact heat exchanger and the absorber.
Preferably, the gas-liquid contact in the absorber adopts a counter-current spraying mode, the gas enters from the lower part of the absorber and flows out from the top, and the absorption solution enters from the upper part and flows out from the bottom. The absorbing solution is a metal halide solution, such as lithium bromide (LiBr-H) 2 O), aqueous lithium chloride solution (LiCl-H) 2 O) solution and calcium chloride aqueous solution (CaCl) 2 -H 2 O), the solution concentration needs to be lower than the crystallization concentration at the design temperature of the absorption process.
The expander may be a positive displacement expander, and may be a scroll type, screw type, piston type, rolling rotor type or the like.
Preferably, a pipeline connecting the condenser and the condensed water tank extends into the condensed water tank and is submerged into a certain liquid level, a pipeline connecting the condensed water tank and the vacuum pump extends into the condensed water tank, and a pipe orifice is positioned above the liquid level.
Preferably, the vacuum pump is a water-ring vacuum pump because the moisture content of the regenerator gas outlet is still high.
Preferably, the regenerator adopts a low-pressure heating evaporation mode, the absorption solution enters the regenerator from the upper part, the regenerated concentrated solution flows out from the bottom of the regenerator, and the regenerated steam flows out from the top of the regenerator.
Preferably, the evaporation area in the regenerator is provided with a heating coil, the heating coil is positioned below the solution spraying area of the regenerator, the heating adopts an indirect heat exchange mode, a heating heat source can adopt the modes of steam turbine air exhaust, high-temperature flue gas, electric heating, high-temperature steam and the like, and the determination can be carried out according to the requirements of specific scenes.
Compared with the prior art, the invention has the following advantages:
1. the invention provides a new system, which integrates water collection and waste heat recovery, pollutant removal and flue gas expansion work recycling into a system, so that the flue gas after waste heat recovery and pollutant removal is directly used for generating mechanical energy, and then mechanical energy or electric energy is output and used as an energy source of a vacuum pump, a circulating water pump or surrounding small equipment of the system, thereby achieving the integral integrated system of water collection and waste heat recovery, pollutant removal and high-humidity gas expansion work recycling. Compared with the prior application, the system can further improve the utilization of the waste heat of the high-temperature and high-humidity gas, the recovery of water, the capture of pollutant components and the recycling of gas expansion work.
2. In the device, high-temperature high-humidity gas is subjected to contact heat exchange with water after the pressure of the high-temperature high-humidity gas is increased by the gas phase pressure adjusting device, the flue gas at the outlet of the direct contact heat exchanger is still in a pressurized state, and when the flue gas is subjected to absorption reaction with an absorption solution, the absorption process driving force is the difference value between the partial pressure of the water vapor and the surface vapor pressure of the absorption solution, so that the vapor pressure difference is larger and the driving force is stronger compared with the vapor pressure difference in the absorption process under the normal pressure state, and the absorption efficiency is better than the normal pressure after pressurization under the same equipment working condition, so that the process can absorb more water vapor, the latent vaporization heat entering liquid circulating water is further increased, and the water heat recovery efficiency of the device is obviously improved compared with that of the traditional method.
3. In the device, high-pressure saturated high-temperature high-humidity gas enters the absorber, after the absorption solution absorbs moisture, the relative humidity of the high-temperature high-humidity gas is further reduced, sensible heat and latent heat of the gas are further recovered, after the expansion machine applies work, the final outlet pressure of the gas is atmospheric pressure, the final outlet temperature of the gas is lower than the corresponding saturated temperature under the atmospheric pressure, and the high-temperature high-humidity gas is in an unsaturated state, so that the generation probability of white smoke is reduced.
4. In the device, high-temperature and high-humidity gas enters the absorber after being sprayed and washed by circulating water and is absorbed by the absorption solution, so that the pollution of residual components in smoke to the absorption solution can be reduced, and the running cost and the fault risk of a system are reduced.
5. In the device, high-temperature and high-humidity gas enters the turbine to release pressure after being absorbed, wherein the water vapor is in an unsaturated state, so that the water vapor can not be condensed to generate liquid drops in the pressure release process, the water-carrying operation of the turbine is avoided, and the safe operation of an expansion working procedure is ensured.
6. In the operation process of the system, circulating water serves as a heat-carrying working medium for outputting heat outwards and flows through the solution-water heat exchanger, the condenser and the contact heat exchanger in sequence.
Drawings
FIG. 1 is a schematic diagram of an open compression absorption heat pump system for hydrothermal recovery in high temperature and high humidity gas;
the system comprises a gas pressure adjusting device 1, a gas pressure adjusting device 2, a pressure control valve 3, a contact type heat exchanger 4, an absorber 5, a pressure control valve 6, an expander 7, a condensation water tank 8, a vacuum pump 9, a condenser 10, a solution water heat exchanger 11, circulating water pumps I and 12, circulating solution pumps I and 13, a solution heat exchanger 14, a regenerator 15, circulating solution pumps II and 16, a user side heat output device 17, circulating water pumps II and 18 and a circulating water tank.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
Figure 1 shows an open compression absorption heat pump system for hydrothermal recovery in high temperature and high humidity gas. As shown in fig. 1, the system includes a gas pressure adjusting device 1, a contact heat exchanger 3, pressure control valves 2 and 5, an expander 6, an absorber 4, a solution-water heat exchanger 10, a solution heat exchanger 13, a condenser 9, a regenerator 14, a condensate water tank 7, a vacuum pump 8, a circulation water tank 18, and a user-side heat output device 16. An outlet of a gas pipeline is connected with a contact type heat exchanger 3, a gas pressure adjusting device 1 is arranged on the gas pipeline, the contact type heat exchanger 3 is connected with an absorber 4, a gas outlet at the upper end of the absorber 4 is connected with an expander 6, and a first pressure control valve 5 is arranged on a pipeline between the absorber 4 and the expander 6; a circulating water inlet is connected with a solution-water heat exchanger 10, the solution-water heat exchanger 10 is connected with a condenser 9, the condenser 9 is connected with a contact heat exchanger 3, the lower end of the contact heat exchanger 3 is connected with a circulating water tank 18, the circulating water tank 18 is connected with a user side heat output device 16, and the user side heat output device 16 is connected with the solution-water heat exchanger 10; the absorber 4 is connected with a solution heat exchanger 13, the solution heat exchanger 13 is connected with a regenerator 14, the bottom end of the regenerator 14 is connected with the solution heat exchanger 13, the solution heat exchanger 13 is connected with a solution water heat exchanger 10, and the solution water heat exchanger 10 is connected with the absorber 4; the regenerator 14 is connected with a condenser 9, and the condenser 9 is connected with a vacuum pump 8; the expander 6 delivers energy to a vacuum pump 8.
The system comprises four working mediums: high-temperature high-humidity gas, circulating water, absorption solution and regenerated steam.
The high-temperature high-humidity gas enters the contact heat exchanger 3 through the gas pipeline outlet, exchanges heat with circulating water in the contact heat exchanger 3, enters the absorber 4 after heat exchange, carries out absorption reaction with a solution in the absorber 4, enters the expander 6 after absorption, pushes the expander to do work, and outputs mechanical energy. And finally discharging the expanded gas to the atmosphere.
The circulating water exchanges heat with gas in the contact heat exchanger 3, enters the circulating water tank 18, then enters the user side heat output device 16 from the circulating water tank 18, enters the solution water heat exchanger 10 after the user side heat output device 16 exchanges heat, exchanges heat with regenerated concentrated solution, enters the condenser 9 to exchange heat with regenerated steam from the regenerator 14, and then enters the contact heat exchanger 3 to complete circulating water circulation.
The absorption solution enters the solution heat exchanger 13 after undergoing absorption reaction with gas in the absorber 4, enters the regenerator 14 for regeneration after exchanging heat with the solution from the regenerator 14, enters the solution water heat exchanger 10 after exchanging heat with the concentrated solution generated after regeneration, enters the absorber 4 after exchanging heat with the circulating water, and completes solution circulation.
The regeneration steam is generated in the solution regeneration process in the regenerator 14, enters the condenser 9 to exchange heat with circulating water and then enters the condensed water tank 7, the condensed water tank 7 is connected with the vacuum pump 8, and the regeneration steam is condensed into the condensed water tank 7.
Preferably, the circulating water releases heat from the user-side heat output device 16, then passes through the solution-water heat exchanger, the condenser and the contact heat exchanger, finally returns to the circulating water tank, and is pumped into the user-side heat output device 16 to complete circulation after water lifting, purification and other operations. The process can realize the gradual temperature rise of circulating water and realize the cascade utilization of waste heat resources.
Preferably, the gas pressure regulating device 1 comprises a compressor. After the high-temperature high-humidity gas is pressurized by the gas pressure regulating device 1, the temperature of the high-temperature high-humidity gas rises, the high-temperature high-humidity gas is changed from a saturated state at an inlet into an overheated state, the pressure dew point temperature of the high-temperature high-humidity gas rises along with the rise of the pressure, more water can be condensed when the high-temperature high-humidity gas is subjected to contact type heat exchange with water, the latent heat of vaporization entering liquid circulating water is further increased, and the water heat recovery efficiency of the device is obviously improved compared with that of the traditional method.
Preferably, the gas-liquid contact in the contact heat exchanger 3 is performed by countercurrent spray, and a gas-liquid contact reaction apparatus such as a spray tower, a plate tower, or a packed tower can be used. Circulating water enters from the upper part and flows out from the bottom, and gas enters from the lower part of the spraying position and flows out from the top. Preferably, the bottom connecting pipe of the contact heat exchanger 3 opens into the circulation tank 18, submerged below the liquid level.
Preferably, the tail end of the circulating water connecting pipeline is connected with a spraying device, and the connecting pipeline of the gas pressure regulating device 1 and the contact type heat exchanger 3 extends into the contact type heat exchanger 3 and is positioned at the lower part of the spraying device. The spraying of spraying device makes gas and water carry out intensive mixing heat transfer, improves heat exchange efficiency.
Preferably, the temperature of the gas flowing through the contact heat exchanger 3 is high, and the internal pressure of the gas is higher than that of the external environment, so that the design material needs to be a pressure-resistant material such as stainless steel. The pressure in the heat exchanger is the sum of the pressurization amount of the gas pressure regulating device and the ambient pressure, if the ambient pressure is 101.3kPa, and the gas pressurization amount is 80kPa, the pressure in the heat exchanger is 181.3kPa, and the regulation and control can be carried out through pressure control valves arranged at an upper side gas outlet and a lower side hot water outlet of the heat exchanger.
Preferably, a demister, demister is arranged above the interior of the contact heat exchanger 3 for filtering out liquid droplets entrained with the gas. The demister can be a wire mesh demister, and the demister can be a baffle demister. The demister is arranged at the upper part of the demister, and a connecting pipeline between the absorber and the contact type heat exchanger extends into the contact type heat exchanger and is arranged at the lower part of the demister. Because recirculated cooling water adopts the form of spraying to get into contact heat exchanger, inside air and cooling water reverse contact and the velocity of flow is higher, and accessible defroster and demister carry out the entrapment to large granule liquid drop fixedly.
Preferably, a filtering device, a dosing water replenishing port and a water intake port are arranged in the circulating water tank 18, and the dosing water replenishing port and the water intake port are arranged at the lower part of the filtering device.
Preferably, a circulating water pump II 17 is arranged on a pipeline between the circulating water tank 18 and the user side heat output device 16, and a circulating water pump I11 is arranged on a pipeline between the user side heat output device 16 and the solution water heat exchanger 10.
Preferably, a circulating solution pump I12 is arranged on a pipeline between the absorber 4 and the solution heat exchanger 13, and a circulating solution pump II 15 is arranged on a pipeline between the regenerator 14 and the solution heat exchanger 13.
Preferably, the gas-liquid contact in the absorber 4 is in the form of a counter-current spray, the absorption solution entering from aboveAnd gas flows in from the bottom, enters from the lower part of the solution spraying position of the absorber and flows out from the top. Preferably, the absorption solution is calcium chloride aqueous solution (CaCl) 2 -H 2 O)。
The gas inlet is connected with a gas pressure regulating device, the gas pressure regulating device is connected with a contact type heat exchanger, a gas outlet at the upper end of the contact type heat exchanger is connected with an absorber, a gas outlet at the upper end of the absorber is connected with an expander, a first pressure control valve is arranged on a pipeline between the absorber and the expander, a hot water outlet at the lower end of the contact type heat exchanger is connected with a circulating water tank, a second pressure control valve is arranged on a pipeline between the hot water outlet and the circulating water tank, the circulating water tank is connected with a user side heat output device, the user side heat output device is connected with a solution water heat exchanger, and the expander externally transmits energy.
The pressure control valve 2 and the pressure control valve 5 are used for controlling pressure parameters in the contact heat exchanger 3 and the absorber 4, and can be a self-standing pressure control valve or a digital pressure control valve. Because the system is continuously charged, the system utilizes a self-supporting pressure control valve or a digital pressure control valve to perform intermittent pressure control. The digital pressure control valve is selected for the present embodiment.
The heat pump system can be divided into a high pressure area and a low pressure area according to pressure, and the pressure is controlled through a pressure control valve 2 and a pressure control valve 5. The pressure in the contact heat exchanger 3 and the absorber 4 is maintained at a higher pressure condition. The pressure control valve adopts a post-valve decompression mode, and the pressure control value is consistent with the set value of the gas pressure regulating device. When the pressure in the contact heat exchanger 3 and/or the absorber 4 is lower than a set value, the control valves 2 and 5 are in a closed state, the boosted gas is enriched in the contact heat exchanger 3 and the absorber 4, especially in the absorber 4, and the internal pressure is gradually increased; when the pressure in the contact heat exchanger 3 and/or the absorber 4 is higher than a set value, the control valves 2 and 5 are in an open state, the gas leaves the absorber 4 through the control valve 5, the internal pressure is gradually reduced, the control valves are reset, and finally the closed state is recovered. Taking the pressure in the heat exchanger as positive pressure of 80kPa as an example, the liquid level height of the heat exchanger is 1m, and the ambient pressure is 101kPa, the pressure control parameter of the first pressure control valve is 181kPa, and the pressure control parameter of the second pressure control valve is the difference between the pressure in the heat exchanger and the liquid level head pressure (9.8 kPa), that is, 171.2kPa. Through the arrangement, the gas output by the absorber 4 can be ensured to have certain pressure, so that the expander 6 is ensured to do work, and mechanical energy with ensured quality is output.
Preferably, the expander 6 can be a positive displacement expander, and can be a scroll type, screw type, piston type, rolling rotor type machine, etc. according to the input gas parameters and the output power requirement, and a screw type expander is used in this embodiment.
Preferably, the solution-water heat exchanger 10 is used to lower the temperature of the concentrated absorption solution entering the absorber, effectively increasing and improving absorption efficiency, and transferring solution heat to the circulating water.
Preferably, the solution heat exchanger 13 is used for transferring heat of the strong absorption solution to the weak absorption solution, and the design form can reduce the temperature of the strong absorption solution which is heated and regenerated, which is beneficial to improving the absorption efficiency of the absorption solution in the absorber; meanwhile, the temperature of the dilute absorption solution after the absorption reaction can be increased, which is beneficial to reaching the working condition set by the regeneration device and reducing the heat required by the heating of the regenerator 14.
Preferably, the condenser 9 is used for condensing the regeneration steam to realize indirect recovery of moisture in the high-temperature and high-humidity gas.
Preferably, the condenser 9 adopts indirect contact condensation, circulating water from a solution-water heat exchanger is used as a cooling medium, regeneration steam is used as a heat-carrying medium, and the circulating water absorbs latent heat of vaporization released in the condensation process of the regeneration steam.
Preferably, a pipeline connecting the condenser 9 and the condensate tank 7 extends into the condensate tank and is submerged in a certain liquid level, a pipeline connecting the condensate tank and the vacuum pump extends into the condensate tank, and a pipe orifice is positioned above the liquid level. By the design, large condensed liquid drops can be guaranteed to flow through the condensed water tank, the liquid drops are fully captured by the existing condensed liquid, and the liquid drops cannot influence the work of the vacuum pump; meanwhile, the non-condensable gas can smoothly flow out of the condensate water tank through the upper vacuum pump connecting pipeline, and the system is guaranteed to be maintained in a set negative pressure state.
Preferably, the evaporation area in the regenerator 14 is provided with a heating coil, the heating coil is positioned below the solution spraying area of the regenerator, the heating adopts an indirect heat exchange mode, the heating heat source can adopt the modes of steam turbine air exhaust, high-temperature flue gas, high-temperature steam, electric heating and the like, and the determination can be carried out according to the requirements of specific scenes.
Preferably, the regenerator 14 is a low-pressure heating evaporation type, the absorption solution enters the regenerator from the upper part, the regenerated concentrated solution flows out from the bottom of the regenerator, and the regenerated steam generated after regeneration flows out from the top of the regenerator. The pressure set in the regenerator is related to the surface vapor pressure calculated from the concentration and temperature of the absorbing solution. The pressure in the regenerator is less than or equal to the vapor pressure on the surface of the absorption solution under the designed working condition. CaCl as selected in this embodiment 2 -H 2 And (3) calculating the surface vapor pressure of O, wherein a vapor pressure fitting formula given by Manuel R.Conde is selected as follows:
Figure BDA0003213098220000101
Figure BDA0003213098220000102
θ＝-0.379+3.457ξ-3.531ξ 2 # (3)
Figure BDA0003213098220000103
Figure BDA0003213098220000104
Figure BDA0003213098220000105
preferably, the vacuum pump is a water-ring vacuum pump because the moisture content of the regenerator gas outlet is still high.
Preferably, the condensed water tank 7 is connected to the circulating water tank 18, and the condensed water is filtered in the circulating water tank, treated with chemicals, and extracted through a water extraction port.
And the circulating water pump II 17 and the circulating water pump I11 are used for improving the pressure of circulating water in the pipeline. The pressure provided by the circulating water pump I11 is used for ensuring the flowing heat exchange state of circulating water entering the solution-water heat exchanger 10 and the condenser 9, preferably the working state of a nozzle in the contact heat exchanger 3, and the pressure and flow parameters are determined by the spraying working condition of the nozzle. The pressure provided by the circulating water pump II 17 is used for ensuring the flowing heat exchange state of circulating water in the user side heat output device 16, and the pressure, the temperature and the flow parameters are fed back and adjusted by the thermodynamic calculation result of the user side heat output device. The thermodynamic process is calculated by gas-liquid energy balance of the contact heat exchanger 3. In the calculation process, the heat dissipation loss of the equipment is not considered, and the gas-liquid energy balance equation is obtained as follows:
m f Δh f ＝c w m w ΔT w # (7)
wherein m is f 、m w Respectively gas and circulating water mass flow, Δ h f Is the enthalpy difference of gas inlet-outlet ratio of the heat exchanger, c w Is the specific heat capacity, delta T, of circulating water at constant pressure w The temperature difference between the circulating water inlet and the circulating water outlet of the heat exchanger.
The specific enthalpy of gas can be calculated by an empirical formula for the enthalpy of gas:
h＝1.01t+(2500+1.84t)d# (8)
the compressed gas temperature can be calculated according to the relation of the polytropic processes T and P:
Figure BDA0003213098220000111
where n is the polytropic exponent of the thermodynamic process, n =1.55 may be taken.
The moisture content can be calculated by the equations (11) (12).
According to the above equation, the gas parameter can be regarded as having entered the systemKnowing the data, the circulating water temperature difference and the circulating water flow m of the contact heat exchanger can be obtained w The relationship between them.
The user-side heat output device 16 is a user-side heat utilization device, and can adopt a common heat exchange mode to utilize the heat of circulating water. This example uses a domestic radiator heating process as the heat utilization device. The outlet temperature and the hot water quantity can be fed back and adjusted by utilizing the circulating water quantity and the gas pressurization quantity of the system according to the requirements of the user side.
The circulating water tank 18 is positioned below the contact heat exchanger and the pressure control valve, is used for storing circulating water of the system, has a buffering effect, and can also regulate the operating temperature of the system by controlling the flow of the circulating water. After gas-liquid heat exchange is carried out on the circulating water in the contact heat exchanger 3, the circulating water flows to the lower circulating water tank 18 under the action of pressure in the tower. Because trace impurities, particulate matters and the like in the gas are dissolved in the circulating water during the operation of the system, the trace impurities, the particulate matters and the like are enriched in the circulating water after long-term operation, and a water treatment device and a filtering device are required to be arranged in the circulating water tank.
Preferably, the bottom of the circulating water tank 18 is provided with a dosing water replenishing port for dosing the pollutant treating agent, and dosing modes such as timed dosing and continuous dosing can be adopted.
Preferably, the bottom of the circulating water tank 18 is provided with a water intake, so that the mass balance of the original moisture of the system can be broken by long-term operation because the water vapor in the gas extracted by the system enters the circulating water, and the recovered moisture needs to be extracted. Meanwhile, the water intake can also be used for discharging the circulating water in the circulating water tank 18.
Preferably, a filtering device is provided inside the circulation tank 18 for filtering the particulate matter or the precipitated matter having a relatively large particle size.
As shown in fig. 1, in the working method of water collection and waste heat recovery, high-temperature and high-humidity gas enters a gas pressure regulating device through a gas pipeline, is compressed into high-temperature and high-pressure gas, and then is introduced into a contact heat exchanger, the high-temperature and high-pressure gas and circulating water perform direct contact heat exchange, wherein sensible heat is released by cooling the gas, and latent heat of vaporization is further released after water vapor in the gas reaches a saturated state, so that recovery of latent heat of vaporization of the gas is realized; then the gas enters an absorber to perform absorption reaction with the concentrated absorption solution, water vapor in the gas is further absorbed by the absorption solution, latent heat of vaporization of the water vapor enters the absorption solution, the high-temperature and high-humidity gas after temperature reduction and dehumidification enters an expander, the expander impeller is pushed to rotate by virtue of the expansion force of the high-pressure gas, mechanical energy is output to coaxially drive a vacuum pump or a circulating water pump motor or an external generator to work, and finally the gas is discharged in a normal pressure state; the circulating water is subjected to contact heat exchange with gas in a contact heat exchanger, then enters a circulating water tank, is subjected to filtration and removal treatment processes, is pressurized in a circulating water pump II and then is pumped to a user side heat output device to release heat, the cooled circulating water is pressurized by a circulating water pump I and then enters a solution water heat exchanger, the regenerated concentrated solution is cooled again, enters a condenser to exchange heat with regenerated steam, and then returns to the contact heat exchanger to spray to complete circulation; the concentrated absorption solution is contacted with high-pressure saturated high-temperature high-humidity gas in an absorber to generate absorption reaction, water vapor enters the solution to reduce the concentration of the solution, the dilute solution is pumped to a solution heat exchanger through a booster pump of a circulating solution pump II to exchange heat with the regenerated concentrated solution, then the dilute solution enters a regenerator to be heated and regenerated at low pressure, the regenerated concentrated solution is pumped to the solution heat exchanger through a circulating solution pump I to exchange heat with circulating water again, and then the regenerated concentrated solution enters the absorber to be sprayed to complete circulation; the regeneration steam generated in the regeneration process is driven by the negative pressure generated by the vacuum pump to enter the condensate tank to remove the condensate, and the residual non-condensable gas is discharged to the atmospheric environment.
Preferably, the compressor of the gas pressure regulating device 1 may be a gas pressure transmitter such as a vapor compressor or a roots blower. Because the moisture content in the high-temperature and high-humidity gas is higher, modes such as coating anticorrosion, material anticorrosion and the like can be adopted. The variable-frequency compressor is selected, the power of the compressor can be adjusted, and the variable-frequency compressor is used for adjusting the flow parameters of the system. The power of the pressure adjusting device can be adjusted according to actual needs, so that the flow of the conveyed gas changes according to needs; and adjusting the threshold value of the pressure control valve according to actual needs, so that the temperature and the pressure of the gas in the contact type heat exchanger are changed according to needs. For example, when the detected pressure and temperature of the gas output from the contact heat exchanger are lower than the preset pressure and temperature, the system intelligently adjusts the transmitted power and the valve threshold value, so that the pressure of the output gas is increased, thereby ensuring the temperature and flow of the hot water outlet entering the contact heat exchanger to meet the heat supply requirement, and further changing the parameters of the gas entering the expansion machine.
Preferably, a temperature and/or pressure sensor is arranged at a gas outlet at the upper part of the contact heat exchanger 3 and used for detecting the temperature and/or pressure of the discharged gas, the gas pressure adjusting device 1, the temperature and/or pressure sensor and a controller are in data connection, and the controller automatically adjusts the power of the gas pressure adjusting device 1 according to the detected temperature and/or pressure, so that the flow rate of the gas entering the contact heat exchanger, the temperature and the flow rate of a hot water outlet after heat exchange are ensured to meet the heat supply requirement, and further the parameters of the gas entering the expansion machine are changed.
Preferably, when the detected gas temperature is lower than the set temperature and/or pressure lower limit, the controller controls the power of the gas pressure regulating device to be increased, so that the gas pressure entering the contact heat exchanger is increased, and the gas temperature in the contact heat exchanger is further increased; and simultaneously, the controller controls the pressure control valve to increase the threshold value, so that the temperature and the pressure of the gas in the contact type heat exchanger are increased.
Preferably, when the detected gas temperature is higher than the set temperature and/or pressure upper limit, the controller controls the power of the gas pressure regulating device to be reduced, so that the gas pressure entering the contact heat exchanger is reduced, and the gas temperature in the contact heat exchanger is further increased; and simultaneously, the controller controls the pressure control valve to reduce the threshold value, so that the temperature and the pressure of the gas in the contact type heat exchanger are reduced.
The compression power of the gas pressure regulating device 1 is controlled according to the temperature/pressure of the gas at the outlet of the contact heat exchanger 3, so that the pressure and the temperature entering the contact heat exchanger 3 can meet the heat exchange requirements of the contact heat exchanger.
Preferably, the circulating water pump I11 is in data connection with a controller, and the controller controls the power of the circulating water pump I11 according to the temperature of the gas outlet at the upper part of the contact heat exchanger 3.
Preferably, a temperature and/or pressure sensor is arranged at a gas outlet at the upper part of the contact heat exchanger 3 and is used for detecting the temperature and/or pressure of discharged gas, the circulating water pump I11 and the temperature sensor are in data connection with a controller, and the controller automatically adjusts the power of the circulating water pump I11 according to the detected temperature and/or pressure, so that the temperature and flow of hot water entering the contact heat exchanger are ensured to meet the heat supply requirement, and the parameters of gas entering the turbine are further changed.
Preferably, when the detected gas temperature is lower than the set temperature and/or pressure lower limit, the controller controls the power of the circulating water pump I11 to be reduced, so that the flow of a cold source entering the contact type heat exchanger is reduced; meanwhile, the circulating water sequentially flows through the solution water heat exchanger and the condenser, and the outlet temperature of the circulating water in the two devices can be increased due to the reduction of the flow of the cold source, so that the temperature of the circulating water entering the contact heat exchanger is increased, and finally, the temperature and the pressure of the gas output by the contact heat exchanger 3 are increased.
Preferably, when the detected gas temperature is higher than the set upper temperature and/or pressure limit, the controller controls the power of the circulating water pump I11 to be increased, so that the flow of the cold source entering the contact type heat exchanger is increased; meanwhile, the circulating water sequentially flows through the solution water heat exchanger and the condenser, the outlet temperature of the circulating water in the two devices can be reduced due to the increase of the flow of the cold source, the temperature of the circulating water entering the contact heat exchanger is reduced, and therefore the temperature and the pressure of the gas output from the contact heat exchanger 3 are reduced. Through so setting up, the heat transfer condition among the steerable contact heat exchanger further controls contact heat exchanger hot water outlet temperature, better satisfying user's needs.
Through the power size of foretell according to 3 export gas temperature pressure control circulating water pump I11 of contact heat exchanger, can realize guaranteeing to leave the pressure and the temperature of 3 gas of contact heat exchanger, circulating water and satisfy the requirement, satisfy the absorption technology needs simultaneously.
The gas outlet at the upper part of the contact type heat exchanger 3 is provided with a temperature and humidity and/or pressure sensor for detecting the temperature and humidity and/or pressure of discharged gas, the circulating solution pump II 15, the circulating solution pump I12 and the temperature and humidity sensor are in data connection with the controller, and the controller automatically adjusts the compression power of the circulating solution pump II 15 and the circulating solution pump I12 according to the detected temperature and humidity and/or pressure, so that the flow of the absorbing solution entering the absorber and the regenerator is adjusted to meet the requirements of absorbing water vapor in the gas and regenerating the solution, and further the moisture parameter of the gas outlet mouth is changed.
Preferably, the circulating solution pump II 15 and the circulating solution pump I12 are in data connection with the controller, and the controller synchronously controls the power of the circulating solution pump II 15 and the power of the circulating solution pump I12 according to the temperature and humidity of the gas outlet at the upper part of the contact heat exchanger 3 because the material balance of the absorbing solution is ensured in the operation process of the system.
Preferably, when the detected temperature and humidity of the gas are lower than the set lower limit of the temperature, the humidity and/or the pressure, the moisture content in the gas is reduced, and the controller controls the power of the circulating solution pump II 15 and the power of the circulating solution pump I12 to be reduced, so that the solution flow entering the absorber and the regenerator are reduced, the absorption and regeneration efficiency is reduced, the volume of the gas is gradually increased, and the temperature and the pressure of the gas output by the absorber 4 are improved.
Preferably, when the detected gas temperature is higher than the set upper limit of temperature and/or pressure, the moisture content in the gas is increased, and the controller controls the power of the circulating solution pump II 15 and the power of the circulating solution pump I12 to be increased, so that the solution flow rate entering the absorber and the regenerator is increased, the absorption and regeneration efficiency is improved, the gas volume is gradually reduced, and the temperature and the pressure of the gas output by the absorber 4 are reduced.
Through the power of the circulating solution pump II 15 and the circulating solution pump I12 controlled according to the temperature and the pressure of the gas at the outlet of the heat exchanger 3, the solution flow entering the absorber 4 and the regenerator can be ensured, the absorption and regeneration efficiency can be further adjusted, and finally the temperature and pressure parameters of the gas in the contact heat exchanger and the gas in the absorber are maintained in a relatively balanced state.
Preferably, the expander 6 and the vacuum pump 8 are in data connection with a controller, the expander 6 being capable of delivering electrical or mechanical energy to the vacuum pump 8, and the controller being capable of controlling the temperature and pressure parameters in the regenerator by controlling the power of the vacuum pump 8 by controlling the amount of energy delivered by the expander 6 to the vacuum pump 8.
Preferably, when the detected temperature, humidity and/or pressure of the regenerator outlet gas is lower than the set lower limit of temperature, humidity and/or pressure, the controller controls the power output by the expansion machine to the vacuum pump to be reduced, so that the vacuum degree of the regenerator is reduced, and the regeneration efficiency is reduced.
Preferably, when the detected temperature, humidity and/or pressure of the regenerator outlet gas is higher than the set lower limit of the temperature, humidity and/or pressure, the controller controls the power output from the expansion machine to the vacuum pump to be increased, so that the vacuum degree of the regenerator is increased, and the regeneration efficiency is improved. By so doing, the regeneration efficiency of the regenerator can be controlled to maintain the mass balance of the absorption solution in the heat pump system.
By controlling the output power of the expansion machine 6 according to the temperature, humidity and pressure of the gas at the regeneration steam outlet of the regenerator 14, the power input to the vacuum pump 8 can be ensured to meet the operation requirement, so that the regeneration pressure in the regenerator meets the regeneration process requirement and the system stability.
Preferably, the vacuum pump and the regenerator heating source are in data connection with a controller, and the controller controls the power of the vacuum pump 8 according to data of temperature, humidity and pressure of the gas inlet and outlet at the upper part of the contact heat exchanger 3, the absorber outlet and the condenser outlet.
Preferably, a temperature and humidity and/or pressure sensor is arranged at a gas outlet at the upper part of the contact heat exchanger 3 and used for detecting the temperature, humidity and/or pressure of discharged gas, a temperature and humidity and/or pressure sensor is arranged at a gas outlet at the upper part of the absorber 4, a temperature and humidity and/or pressure sensor and a flow meter are arranged at a regeneration steam outlet at the upper part of the condenser 9, and the controller automatically adjusts the compression power of the vacuum pump 8 according to the detected temperature and/or pressure, so that pressure parameters entering a regenerator, the condenser and a condensate water tank are ensured, and further, the solution regeneration efficiency is changed to ensure that the system absorption regeneration reaches an equilibrium state.
The vacuum pump 8 is used to create vacuum conditions for the regeneration process, and preferably the power of the vacuum pump is used to control the regeneration process. The vacuum degree provided by the vacuum pump 8 is used for ensuring pressure parameters in the regenerator 14 and the condenser 9, and the pressure, the temperature, the humidity and the flow parameters are fed back and regulated by thermodynamic calculation results of the contact condenser, the absorber and the regenerator. The thermodynamic process is calculated by gas-liquid material balance of gas parameters entering the system, gas parameters at the outlet of the absorber and gas parameters at the outlet of the regenerator. The heat dissipation loss of the equipment is not considered in the calculation process, and the gas-liquid mass balance equation is obtained as follows:
m 4dry ΔH 4-5 ＝m 14dry H 14 # (10)
wherein m is 4dry 、m 14dry Respectively, the mass flow of dry air at the outlet of the absorber and the regenerator, delta H 4-5 Is the difference of moisture content in and out of the absorber, H 14 The regenerator outlet moisture content.
The gas moisture content d can be calculated by the formula:
Figure BDA0003213098220000151
P b is the gas pressure, P S Is the partial pressure of the water vapor,
Figure BDA0003213098220000152
for relative humidity, the saturated vapor pressure of Antoine water can be calculated using the equation of temperature dependence:
Figure BDA0003213098220000153
through the equation, the moisture content can be calculated according to the temperature and pressure parameters of each measuring point of the system, and further the dynamic adjustment of the system is realized.
A working method of an open compression absorption heat pump system for recovering water heat in high-temperature and high-humidity gas comprises the following steps:
high-temperature high-humidity gas enters a gas pressure regulating device through a gas pipeline, is compressed into high-temperature high-pressure gas, is introduced into a contact type heat exchanger, and directly performs contact type heat exchange with circulating water, wherein the gas is cooled to release sensible heat, the latent heat of vaporization of the gas is further released after the water vapor in the gas reaches a saturated state, so that the latent heat of vaporization of the gas is recovered, the gas enters an absorber and is subjected to an absorption reaction with a concentrated absorption solution, the water vapor in the gas is further absorbed by the absorption solution, the latent heat of vaporization of the water vapor enters the absorber, the high-temperature high-humidity gas enters an expander after the absorption solution is cooled and dehumidified, the expander is pushed to do work by virtue of the expansive force of the high-pressure gas, the output mechanical energy coaxially drives a vacuum pump motor or an external generator to do work, and finally the high-temperature high-humidity gas is discharged in a normal-pressure state; circulating water and gas carry out contact heat exchange in a contact heat exchanger, the heated circulating water enters a circulating water tank, after filtration and removal treatment processes, the circulating water is pressurized in a circulating water pump II and then is pumped to a user side heat output device to release heat, the cooled circulating water enters a solution water heat exchanger after being pressurized by a circulating water pump I, the regenerated concentrated solution is cooled again, the cooled circulating water enters a condenser to exchange heat with regenerated steam, and then the cooled circulating water returns to the contact heat exchanger to be sprayed to complete circulation; the concentrated absorption solution is contacted with high-pressure saturated high-temperature high-humidity gas in an absorber to generate absorption reaction, water vapor enters the solution from the high-temperature high-humidity gas to reduce the concentration of the solution, a dilute solution is pumped to a solution heat exchanger through a circulating solution pump II to exchange heat with the regenerated concentrated solution, then the regenerated concentrated solution enters a regenerator to be heated and regenerated at low pressure, the regenerated concentrated solution is pumped to the solution heat exchanger through a circulating solution pump I, then enters a solution water heat exchanger to exchange heat with circulating water again, and then enters the absorber to be sprayed to complete circulation; and the water vapor generated in the regeneration process is driven by the negative pressure generated by the vacuum pump to enter a condensate water tank to remove condensate water, and the residual non-condensable gas is discharged to the atmospheric environment.
After the pressure of the saturated high-temperature high-humidity gas is increased by the gas pressure adjusting device, the water vapor in the high-temperature high-humidity gas is changed from a saturated state to an overheated state, and the dew point temperature of the high-temperature high-humidity gas is increased along with the increase of the pressure. For example, the pressure-increasing ratio is 1.8 times, and the temperature of the saturated high-temperature and high-humidity gas at 50 ℃ can be increased to about 125 ℃. Because the temperature of the circulating water is far lower than the temperature of the superheated air, after the gas and the liquid are directly contacted, the temperature of the superheated gas is reduced to the saturation temperature of the vapor under the pressure, and the sensible heat of the gas is released in the process; the saturated gas is further cooled and releases heat due to the gas-liquid temperature difference, and the sensible heat of the dry air component and the latent heat of vaporization of the water vapor are released in the stage.
Since the dew point of the high-temperature and high-humidity gas is increased, the amount of condensable water condensed to the same temperature is increased as compared with that of the conventional normal-pressure contact condenser. Therefore, the recovery of the water vapor in the high-temperature and high-humidity gas can be realized.
The high-temperature high-humidity gas after contact heat exchange enters an absorber, under the drive of the difference value of the saturation partial pressure of the water vapor of the high-temperature high-humidity gas and the partial pressure of the water vapor on the surface of an absorption solution, the water vapor in the high-temperature high-humidity gas is absorbed by the absorption solution, and the latent heat of vaporization of the water vapor enters the absorption solution along with the absorption process.
Because the pressure of the high-temperature and high-humidity gas in the absorber is still higher than the normal pressure, and the partial pressure of the water vapor is higher than that of the saturated vapor with the same temperature under the normal pressure state, the partial pressure difference in the absorption process is larger than that under the normal pressure, and the absorption reaction can be promoted.
The atomized circulating water drops and the small-particle-size condensed water drops can be used as crystal nuclei to adsorb pollutant gas molecules and particles in the flue gas, the diffusion effect is further promoted under the pressurization effect, and the adsorption capacity is enhanced. After temperature reduction and moisture absorption, the gas leaves the absorber and enters the expander, and the expandable power generation or the output mechanical energy coaxially drives the vacuum pump motor to do work. The gas temperature after the pressure release to the normal pressure is further lowered and is in an unsaturated state. The circulating water absorbs the sensible heat of gas and the latent heat of vaporization of water vapor in the contact process, the temperature of the circulating water rises, and the circulating water is used as an output heat source to supply heat to the outside after leaving the heat exchanger.
In the whole process of the system, the utilization of the waste heat of the high-temperature high-humidity gas, the recovery of moisture and the capture of pollutant components in the flue gas can be realized, and the system has extremely strong engineering practice significance.
Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected by one skilled in the art without departing from the spirit and scope of the invention, as defined in the appended claims.

Claims (6)

1. An open compression absorption heat pump system for recovering water heat in high-temperature and high-humidity gas comprises a contact heat exchanger, a gas pressure adjusting device, a pressure control valve, an expander, a solution heat exchanger, a condensation water tank, an absorber, a regenerator, a vacuum pump, a circulation water tank and a user side heat output device, wherein an outlet of a gas pipeline is connected with the contact heat exchanger; the circulating water inlet is connected with the solution-water heat exchanger, the solution-water heat exchanger is connected with the condenser, the condenser is connected with the contact heat exchanger, the lower end of the contact heat exchanger is connected with the circulating water tank, the circulating water tank is connected with the user side heat output device, and the user side heat output device is connected with the solution-water heat exchanger; the absorber is connected with a solution heat exchanger, the solution heat exchanger is connected with the regenerator, the solution heat exchanger is connected with a solution water heat exchanger, and the solution water heat exchanger is connected with the absorber; the regenerator is connected with a condenser, and the condenser is connected with a vacuum pump; the expander transmits energy to the vacuum pump;
high-temperature and high-humidity gas enters the contact type heat exchanger through the outlet of the gas pipeline, exchanges heat with circulating water in the contact type heat exchanger, enters the absorber after heat exchange, carries out absorption reaction with solution in the absorber, enters the expander after absorption, pushes the expander to do work, outputs mechanical energy, and finally discharges the expanded gas to the atmosphere;
circulating water enters a circulating water tank after exchanging heat with gas in a contact type heat exchanger, then enters a user side heat output device from the circulating water tank, enters a solution water heat exchanger after exchanging heat with a user side heat output device, exchanges heat with regenerated concentrated solution, enters a condenser after exchanging heat, exchanges heat with regenerated steam from a regenerator, and then enters the contact type heat exchanger to finish circulating water circulation;
absorbing solution enters a solution heat exchanger after undergoing an absorption reaction with gas in an absorber, enters a regenerator for regeneration after exchanging heat with solution from the regenerator, enters a solution water heat exchanger after exchanging heat with concentrated solution generated after regeneration, enters an absorber after exchanging heat with circulating water, and completes solution circulation;
the regenerated steam is generated in the solution regeneration process in the regenerator, enters the condenser to exchange heat with circulating water, then enters the condensation water tank, the condensation water tank is connected with the vacuum pump, and the regenerated steam is condensed into the condensation water tank.
2. The system as claimed in claim 1, wherein a second pressure control valve is arranged on a pipeline of the circulating water tank and the contact type heat exchanger, a circulating water pump I is arranged between the user side heat output device and the solution water heat exchanger, and a circulating water pump II is arranged between the circulating water tank and the user side heat output device; a pipeline between the absorber and the solution heat exchanger is provided with a circulating solution pump I, and a pipeline between the regenerator and the solution heat exchanger is provided with a circulating solution pump II.
3. The system of claim 1, wherein the pipe connecting the condenser to the condensate tank extends into the condensate tank and is submerged in a liquid level, the pipe connecting the condensate tank to the vacuum pump extends into the condensate tank, and the pipe orifice is located above the liquid level; adopt the low pressure heating evaporation form in the regenerator, the inside heating coil that sets up of regenerator, absorption solution gets into the regenerator from the top in, and the concentrated solution flows out by the regenerator bottom after the regeneration, and the regenerated steam flows out by the regenerator top after the regeneration.
4. The system of claim 1, wherein the gas pressure regulating device comprises a compressor.
5. The system of claim 1, wherein the pressure of the gas in the absorber and the contact heat exchanger is maintained at the same level, which is the sum of the pressurization of the gas pressure regulating device and the ambient pressure.
6. A method for hydrothermal recovery and pollutant removal of high-temperature high-humidity gas according to the system of claim 1 is characterized in that the high-temperature high-humidity gas enters a gas pressure regulating device through a gas pipeline, is compressed into high-temperature high-pressure gas, and then is introduced into a contact type heat exchanger, the high-temperature high-pressure gas and circulating water perform direct contact type heat exchange, the temperature of the gas is reduced to release sensible heat, the latent heat of vaporization is further released after the water vapor in the gas reaches a saturated state, the recovery of the latent heat of vaporization of the gas is realized, then the gas enters an absorber and is subjected to absorption reaction with a concentrated absorption solution, the water vapor in the gas is further absorbed by the absorption solution, the latent heat of vaporization of the water vapor enters the absorber, after the absorption solution is cooled and dehumidified, the high-temperature high-humidity high-temperature gas enters an expander, the expander is pushed to do work by virtue of the expansive force of the high-pressure gas, and mechanical energy is coaxially driven to a vacuum pump motor or an external generator to do work, and finally the normal-pressure state is achieved and the discharge; the circulating water and gas exchange in a contact type heat exchanger in a contact type, the heated circulating water enters a circulating water tank, is subjected to filtering and removal treatment processes, is pressurized by a circulating water pump II and then is pumped to a user side heat output device to release heat, the cooled circulating water enters a solution water heat exchanger after being pressurized by a circulating water pump I, the regenerated concentrated solution is cooled again, enters a condenser to exchange heat with regenerated steam, and then returns to the contact type heat exchanger to spray to complete circulation; the concentrated absorption solution is contacted with high-pressure saturated high-temperature high-humidity gas in an absorber to generate absorption reaction, water vapor enters the solution from the high-temperature high-humidity gas to reduce the concentration of the solution, the dilute solution is pumped to a solution heat exchanger through a circulating solution pump II to exchange heat with the regenerated concentrated solution, then enters a regenerator to be heated and regenerated at low pressure, the regenerated concentrated solution is pumped to the solution heat exchanger through a circulating solution pump I to exchange heat with circulating water again, and then enters the absorber to be sprayed to complete circulation; and the water vapor generated in the regeneration process is driven by the negative pressure generated by the vacuum pump to enter a condensate water tank to remove condensate water, and the residual non-condensable gas is discharged to the atmospheric environment.
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