CN116123552A - Low-temperature flue gas efficient heat supply heat pump unit - Google Patents

Low-temperature flue gas efficient heat supply heat pump unit Download PDF

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Publication number
CN116123552A
CN116123552A CN202310061845.0A CN202310061845A CN116123552A CN 116123552 A CN116123552 A CN 116123552A CN 202310061845 A CN202310061845 A CN 202310061845A CN 116123552 A CN116123552 A CN 116123552A
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heat
flue gas
low
heat pipe
pump unit
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张跃
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Broad Air Conditioning Co ltd
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Broad Air Conditioning Co ltd
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Priority to CN202310061845.0A priority Critical patent/CN116123552A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00—Arrangements of devices for treating smoke or fumes
    • F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D15/00—Other domestic- or space-heating systems
    • F24D15/04—Other domestic- or space-heating systems using heat pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H8/00—Fluid heaters characterised by means for extracting latent heat from flue gases by means of condensation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
    • F28F21/08—Constructions of heat-exchange apparatus characterised by the selection of particular materials of metal
    • F28F21/081—Heat exchange elements made from metals or metal alloys
    • F28F21/082—Heat exchange elements made from metals or metal alloys from steel or ferrous alloys

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

The low-temperature flue gas efficient heat supply heat pump unit comprises a heat pipe type first heat pump unit and a heat pipe water heater, wherein the heat pipe type first heat pump unit comprises a heat pipe generator; the gravity type heat pipes are divided into an evaporation section and a condensation section; the evaporation section of the gravity type heat pipe in the heat pipe generator is used for carrying out heat exchange with low-temperature flue gas; the condensing section is used for carrying out heat exchange with dilute solution from an absorber of the heat pipe type first heat pump unit; the evaporation section of the gravity type heat pipe in the heat pipe water heater is used for carrying out heat exchange with the flue gas output by the heat pipe generator; the condensing section is used for carrying out heat exchange with a low-temperature water heat source from an evaporator of the heat pipe type first heat pump unit. The invention can obtain sensible heat and latent heat of low-temperature flue gas, greatly improve the utilization rate of waste heat of the flue gas, improve the grade of heating, and solve the problem that the dew point corrosion generated by acid gas in the flue gas affects the low-temperature heat recovery.

Description

Low-temperature flue gas efficient heat supply heat pump unit
Technical Field
The invention relates to a heat pump unit, in particular to a low-temperature flue gas efficient heat supply heat pump unit.
Background
Waste heat resources in various industries in industrial production account for 17% -80% in fuel consumption, and are mostly discharged in the form of flue gas and the like. The high-temperature and medium-temperature flue gas waste heat resources have higher relative utilization rate, but the low-temperature flue gas waste heat resources have the problems of low grade, high recovery difficulty, long recovery period, flue gas dew point corrosion and the like, and are difficult to utilize for a long time, so that great waste is caused. Once the waste heat of the low-temperature flue gas is utilized, the environmental damage of the flue gas can be reduced, the effective utilization rate of energy sources can be improved, and the energy conservation and the emission reduction can be realized.
The existing equipment such as a tubular heat exchanger, a plate heat exchanger, a waste heat boiler, direct water spraying and the like can be used for directly preparing hot water by using low-temperature flue gas. However, the final exhaust temperature of the flue gas is higher, and the water vapor in the flue gas cannot condense and release heat, so that the latent heat of the flue gas is not utilized. Taking 180 ℃ natural gas fume as an example, if the final exhaust gas temperature is reduced to 60 ℃, the sensible heat which can be obtained is about 2100KJ/m 2, and the latent heat is 0KJ/m 2; if the final flue gas temperature is reduced to 30 ℃, the sensible heat that can be obtained is about 2600 KJ/m. The heat recovery is increased by more than 170% due to the latent heat 3200 KJ/m of condensing water vapor in the flue gas. If these latent heat are obtained by using a tube heat exchanger, a plate heat exchanger, a waste heat boiler, direct water spraying, etc., the inlet temperature of the heat exchanged water is often lower than 20 ℃, and the outlet temperature is about 30 ℃, which is not useful. And the heat pump technology can better utilize low-grade waste heat.
The common smoke type absorption type first heat pump unit can use low-temperature smoke entering a heat pipe generator as a driving heat source to prepare medium-temperature hot water for process and life use. However, it is difficult to simply and economically utilize low-temperature flue gas, mainly because on one hand, the flue gas often contains acid gas and water vapor, and when the temperature of the flue gas is reduced to the combination of the acid gas and the water vapor, strong acid condensation can be generated, and a heat exchanger is severely corroded (commonly called dew point corrosion), so that a high-cost flue gas heat pump unit is damaged, and even an expensive lithium bromide solution is leaked or deteriorated; on the other hand, the low-temperature flue gas temperature is low, the temperature difference between the low-temperature flue gas temperature and the heat pipe generator of the flue gas heat pump unit is small, and the gas heat transfer coefficient is very low, so that a great amount of heat exchange pipes of the heat pipe generator are increased, the consumption of expensive lithium bromide solution is large, and the cost is increased.
In order to solve the above-mentioned problems, in the prior art, a flue gas heat exchanger or a flue gas boiler is used to prepare hot water, and then a hot water type absorption heat pump unit of a first type (hereinafter referred to as a hot water type heat pump unit) is used as a high temperature heat source, as shown in fig. 1. This is in effect a flue gas type absorption heat pump unit of the first type into a waste heat boiler + hot water type heat pump unit. In the method, although corrosive flue gas is isolated from the absorption type first heat pump unit, the temperature and grade of waste heat (high-temperature heat source water) are further reduced by secondary heat exchange, so that the heating capacity and the heating (medium-temperature water) temperature are reduced, and the heat pump efficiency and the utilization efficiency of flue gas waste heat are also reduced. And although the method utilizes the principle that the heat exchange coefficient of hot water is far higher than that of flue gas, the heat exchange pipe consumption of a heat pipe generator of a hot water type heat pump unit and the lithium bromide solution consumption are greatly reduced, but the cost of a heat exchanger or a flue gas hot water boiler is increased, and a water pump and a heat source water pipeline are also required to be added, so that the cost and the running cost are increased.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the low-temperature flue gas efficient heat supply heat pump unit which completely and efficiently utilizes the sensible heat and the latent heat of the flue gas, and has the advantages of high heating grade, high heat exchange coefficient and dew point corrosion resistance.
The technical scheme of the invention is as follows: the low-temperature flue gas efficient heat supply heat pump unit comprises a heat pipe type first heat pump unit and a heat pipe water heater, wherein the heat pipe type first heat pump unit comprises a heat pipe generator; the gravity type heat pipes are divided into an evaporation section and a condensation section; the evaporation section of the gravity type heat pipe in the heat pipe generator is used for carrying out heat exchange with low-temperature flue gas and absorbing the heat of the flue gas; the condensing section is used for carrying out heat exchange with the dilute solution from the absorber of the heat pipe type first heat pump unit and heating the dilute solution; the evaporation section of the gravity type heat pipe in the heat pipe water heater is used for carrying out heat exchange with the flue gas output from the heat pipe generator, and absorbing the heat of the flue gas; the condensing section is used for performing heat exchange with a low-temperature water heat source from an evaporator of the heat pipe type first heat pump unit to heat low-temperature heat source water. The invention can obtain sensible heat and latent heat of low-temperature flue gas, greatly improve the utilization rate of waste heat of the flue gas, improve the grade of heating, and solve the problem that the dew point corrosion generated by acid gas in the flue gas affects the low-temperature heat recovery.
Further, the length of the evaporation section of the gravity type heat pipe is longer than that of the condensation section.
Further, the shell inner cavity of the heat pipe generator is divided into a smoke air cavity and a solution cavity by the partition plate, the evaporation section of the gravity type heat pipe is positioned in the smoke air cavity, the condensation section is positioned in the solution cavity, the solution cavity is internally provided with a liquid distribution device, and the liquid distribution device is communicated with the dilute solution pipeline and the pump set.
Further, a flue gas inlet and a flue gas outlet are arranged in a flue gas cavity of the heat pipe generator, the flue gas outlet is communicated with the heat pipe water heater, and a condensate outlet is arranged at the bottom of the flue gas cavity; the solution cavity of the heat pipe generator is provided with a dilute solution inlet and a concentrated solution outlet, and the top of the solution cavity is provided with a water vapor outlet.
Further, the inner cavity of the shell of the heat pipe water heater is divided into a low-temperature smoke air cavity and a low-temperature water heat exchange cavity by a partition plate; the evaporating section of the gravity type heat pipe is positioned in the low-temperature smoke cavity, and the condensing section is positioned in the low-temperature water heat exchange cavity.
Further, the low-temperature flue gas cavity is provided with a low-temperature flue gas inlet and a cold flue gas outlet, the low-temperature flue gas inlet is communicated with a flue gas outlet pipeline of the heat pipe generator, and the bottom of the low-temperature flue gas cavity is provided with a condensate outlet; the low-temperature water heat exchange cavity is provided with a low-temperature water inlet and a low-temperature water outlet which are communicated with the evaporator pipeline.
Further, the diameter of the gravity type heat pipe is 5-200mm, the length of the evaporation section is 100-3000mm, and the length of the condensation section is 50-1000mm.
Further, the diameter of the gravity type heat pipe is 20-40mm, the length of the evaporation section is 500-1500mm, and the length of the condensation section is 100-500mm.
Further, the heat pipe type first-class heat pump unit is a heat pipe type smoke type absorption type first-class heat pump unit.
Further, holes corresponding to the gravity type heat pipes in number are formed in the partition plate, and the gravity type heat pipes are in sealing connection with the holes in the partition plate by adopting a high-strength heat-resistant method such as welding.
Further, the evaporation section is made of carbon steel, acid-resistant stainless steel, dew point corrosion-resistant low alloy steel or dew point corrosion-resistant stainless steel, and the outer surface of the evaporation section is coated with a Teflon coating, an enamel coating or heat-resistant acid-resistant paint. The combination of various materials can be selected according to the components of the flue gas and the temperatures of different positions, such as carbon steel for the highest temperature section, acid-resistant coating for dew point temperature, and stainless steel for the region where a large amount of condensed water is generated.
Further, the condensing section of the gravity type heat pipe of the heat pipe generator is made of carbon steel or low alloy steel.
Further, the condensing section of the gravity type heat pipe of the heat pipe water heater is made of carbon steel, low alloy steel or stainless steel.
The invention has the beneficial effects that: on one hand, gravity type heat pipes are distributed in the heat pipe generator of the smoke type absorption type first heat pump unit and the heat pipe water heater, and the gravity type heat pipes and the heat pipe water heater are combined to obtain cold smoke with lower temperature, so that sensible heat and latent heat of the smoke are fully utilized, and the waste heat utilization rate of the smoke is greatly improved; because the temperature difference between the evaporation section and the condensation section of the heat pipe is extremely small, the heat pipe generator and the heat pipe water heater both achieve the effect of primary heat exchange, thereby greatly improving the heating efficiency and the heating grade; the material of the evaporation section is designed into acid-resistant materials and acid-resistant coatings, so that the dew point corrosion problem caused by acid gas in the flue gas can be solved; on the other hand, compared with the existing flue gas tubular heat exchanger or flue gas plate heat exchanger, the heat pipe water heater has the advantages that the length of the evaporation section is larger than that of the condensation section, the heat exchange area of the flue gas side can be greatly increased, the problem of low heat exchange coefficient of the flue gas side is solved, the flue gas with lower temperature is further obtained, the flue gas side resistance is small, the smoke discharge and normal combustion are not influenced, and the flue scale is not easy to block.
Drawings
FIG. 1 is a schematic diagram of a connection structure of a hot water type heat pump unit of the prior art;
FIG. 2 is a schematic diagram of a connection principle between a heat pipe heat pump unit and a heat pipe water heater according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the internal structure of a heat pipe generator of a heat pipe heat pump unit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the internal structure of a heat pipe water heater according to an embodiment of the present invention.
Detailed Description
The invention will be described in further detail with reference to the drawings and the specific examples.
As shown in fig. 2 to 4: the low-temperature flue gas efficient heat supply heat pump unit comprises a heat pipe type first heat pump unit (called heat pipe heat pump unit for short) and a heat pipe water heater, wherein the heat pipe heat pump unit comprises a heat pipe generator; the gravity type heat pipes are divided into an evaporation section and a condensation section; the evaporation section of the gravity type heat pipe in the heat pipe generator is used for carrying out heat exchange with low-temperature flue gas and absorbing heat (mainly sensible heat) in the flue gas; the condensing section is used for carrying out heat exchange with the dilute solution with lower temperature of the absorber of the heat pump unit of the heat pipe, and heating and concentrating the solution; the evaporation section of the gravity type heat pipe in the heat pipe water heater is used for carrying out heat exchange with the flue gas output by the heat pipe generator, absorbing heat (mainly latent heat) in the flue gas, and the condensation section is used for carrying out heat exchange with low-temperature personnel water from the evaporator of the heat pipe heat pump unit, so that the water temperature is increased.
In this embodiment, the heat pipe heat pump unit is a heat pipe type smoke absorption type first heat pump unit, and the working medium of the heat pipe generator is lithium bromide, lithium chloride or a mixture thereof, or other absorption type working medium such as ionic liquid. The heat pipe heat pump unit is one kind of heat pump unit with low temperature fume as driving heat source and the low temperature fume as heating water to produce technological or domestic hot water. Heat exchange is carried out between the low-temperature flue gas and the heat pipe in the heat pipe generator; and the sensible heat and the condensation heat (latent heat) of the water vapor in the flue gas are absorbed by the heat pipe water heater. In addition, the construction, interrelationship, and heating principles of other components of the heat pipe heat pump unit (including the evaporator, condenser, absorber, etc.) are similar to those of the conventional flue gas type absorption type first heat pump unit, and the other components are not related to the present technology and therefore are not described further.
The gravity type heat pipe is adopted in the heat pipe generator, so that mass transfer power is not needed by using a heat pipe medium, the temperature difference is almost avoided at the cold and hot ends, the high-strength heat transfer capability is realized, the flue gas is directly used as the heat source of the flue gas type-I heat pump unit, the waste heat grade reduction caused by secondary heat exchange of a waste heat boiler or a flue gas heat exchange pipe and the like is avoided, and the heat pipe generator has better heating grade (namely higher medium-temperature water temperature) and waste heat utilization efficiency (namely lower final flue gas temperature).
Compared with the conventional flue gas tube type heat exchanger and flue gas plate type heat exchanger, the gravity type heat pipe water heater of the embodiment can solve the problem of low heat exchange coefficient of the flue gas side through (a heat pipe evaporation section) large heat exchange area; (2) The flue gas side passage area is large, the air flow resistance is small, and the smoke exhaust and the normal combustion are not influenced; (3) the smoke scale is not easy to be blocked, and the flue is convenient to clean; (4) The dew point corrosion problem caused by acid gases in flue gas can be solved by acid-resistant materials and acid-resistant coatings, and even if the dew point corrosion causes perforation, expensive lithium bromide solution does not deteriorate or leak.
The gravity type heat pipe transfers heat from bottom to top, and a complex tube core is not needed. The medium of the gravity type heat pipe can adopt water solution added with corrosion inhibitor or organic matters suitable for working below 200 ℃.
Specifically, the inner cavity of the shell of the heat pipe generator is divided into a smoke air cavity and a solution cavity by a partition plate, a plurality of holes corresponding to the gravity type heat pipes are arranged on the partition plate, the gravity type heat pipes are in sealing connection with the holes through welding or other firm, heat-resistant and corrosion-resistant methods, so that the evaporation section of the gravity type heat pipes is positioned in the smoke air cavity, and the condensation section is positioned in the solution cavity. If the flue gas cavity of the heat pipe generator is provided with a flue gas inlet and a flue gas outlet, the flue gas inlet is used for introducing medium-temperature and low-temperature flue gas (or other waste heat gases), the flue gas outlet is communicated with the flue gas cavity of the heat pipe water heater, and the bottom of the flue gas cavity of the heat pipe water heater is provided with a condensate outlet. If the solution cavity of the heat pipe generator is provided with a dilute solution inlet and a concentrated solution outlet, and the solution cavity is internally provided with a liquid distribution device, the liquid distribution device is communicated with a dilute solution outlet pipeline of an absorber (often a heat exchanger is arranged between the dilute solution inlet and the dilute solution outlet pipeline) from the heat pipe heat pump unit, and the liquid distribution device is provided with a plurality of nozzles or leak holes, so that the dilute solution can be uniformly sprayed or dripped on the outer wall of the condensing section of the gravity type heat pipe. The top of the solution cavity is provided with a water vapor outlet which is communicated with a condenser of the heat pipe heat pump unit.
In the embodiment, the inner cavity of the shell of the heat pipe water heater is divided into a low-temperature smoke air cavity and a low-temperature water heat exchange cavity by a partition plate; the evaporating section of the gravity type heat pipe is positioned in the low-temperature smoke cavity, and the condensing section is positioned in the low-temperature water heat exchange cavity. The low-temperature flue gas cavity is provided with a low-temperature flue gas inlet and a cold flue gas outlet, the low-temperature flue gas inlet is communicated with a flue gas outlet pipeline of the heat pipe generator, and the bottom of the low-temperature flue gas cavity is provided with a condensate outlet for outputting condensate generated by flue gas; the low-temperature water heat exchange cavity is provided with a low-temperature water inlet and a low-temperature water outlet which are communicated with the evaporator pipeline.
In the embodiment, the length of the gravity type heat pipe evaporation section is longer than that of the condensation section, because the heat pipe is internally provided with high-efficiency phase-change mass transfer and heat transfer, the heat transfer short plate of the whole device is the heat transfer between the heat pipe evaporation section and the flue gas, namely the outer wall of the heat pipe evaporation section is low-efficiency flue gas convection heat transfer, more heat transfer area is needed, and therefore the length of the evaporation section is longer; the outer wall of the condensing section of the heat pipe is liquid phase-change heat exchange, so that the heat exchange efficiency is high, less heat exchange area and less solution are needed, and the cost is greatly reduced. Therefore, the length of the evaporating section of the heat pipe is longer than that of the condensing section.
In the embodiment, the diameter of the gravity type heat pipe is 5-200mm, the length of the evaporation section is 100-3000mm, and the length of the condensation section is 50-1000mm. Further preferably, the diameter of the gravity type heat pipe is 20-40mm, the length of the evaporation section is 500-1500mm, and the length of the condensation section is 100-500mm. For the foregoing reasons, the length of the evaporator section of the heat pipe is greater than the length of the condenser section. The height of the whole heat pipe heat pump unit is slightly higher than the length of the evaporation section plus the length of the condensation section of the heat pipe. Considering the space height of transportation and installation, the height is generally not more than 4000mm (limited by bridges, tunnels and the like in the transportation process), preferably not more than 2500 (convenient for container transportation and high limitation of the layers of a general building), the length and the width are increased and the occupied area is increased due to the requirement of heat exchange area. Therefore, the height of the space is utilized as much as possible. The maximum length (namely the height of the unit) of the heat pipe can be selected in the field assembly, so that the occupied area is reduced as much as possible.
In this embodiment, the surface of the evaporation section of the gravity type heat pipe for heat exchange with the flue gas may be smooth and flat, and for enhanced heat exchange, the surface may be provided with annular or spiral fins, vertical flow guiding grooves or flow guiding ribs, diagonal lines, tree line protrusions or grooves, dot-like protrusions or grooves, or a combination thereof. In addition, because the evaporation section is contacted with the flue gas, according to different flue gas components (particularly corrosive components such as sulfur oxides, and the like), the materials can be carbon steel, acid-resistant stainless steel, dew point corrosion-resistant low alloy steel and dew point corrosion-resistant stainless steel, and Teflon coating, enamel coating and heat-resistant acid-resistant paint can be adopted. In the same heat pipe generator, one or a combination of the above materials may be employed.
In this embodiment, the condenser section of the gravity type heat pipe is contacted with the solution, and the material of the condenser section may be the same as the evaporation section of the heat pipe, or may be different, and preferably low carbon steel or low alloy steel is used from the viewpoints of heat exchange, corrosion resistance, and the like.
In this embodiment, the gravity type heat pipe in the heat pipe water heater may be identical to the gravity type heat pipe structure in the heat pipe generator, or may be configured in different structures, for example, the gravity type heat pipe in the heat pipe water heater has smooth and flat appearance, and the gravity type heat pipe in the heat pipe generator has a protrusion or groove structure; for example, the evaporation section of the gravity type heat pipe in the heat pipe water heater is made of dew point corrosion resistant steel or water vapor corrosion resistant stainless steel, the evaporation section of the gravity type heat pipe in the heat pipe generator is made of carbon steel or low alloy steel, and a coating or dew point corrosion resistant steel can be adopted at the part working at the dew point temperature (related to smoke components).
The working principle of the embodiment is as follows: the medium-low temperature flue gas enters from the flue gas inlet of the heat pipe generator shell, exchanges heat with the evaporation section of each gravity type heat pipe (mainly sensible heat of the flue gas), releases heat of the medium-low temperature flue gas, and then cools down to form lower-temperature flue gas. And the lower-temperature flue gas is discharged from a flue gas outlet into a low-temperature flue gas cavity of the heat pipe water heater. The medium in the evaporation section of the gravity type heat pipe in the heat pipe generator absorbs the heat of the flue gas in the flue gas cavity and evaporates, the generated vapor flows to the condensation section along the inner wall of the gravity type heat pipe, the vapor is sprayed on the outer wall of the condensation section of each gravity type heat pipe through the liquid distribution device after entering the solution cavity, and exchanges heat with the condensation section, so that the vapor in the condensation section is condensed into a liquid working medium, and is recycled under the action of gravity, and meanwhile, the vapor in the condensation section releases heat in the process of condensing into the liquid working medium, and exchanges heat with the sprayed or dripped thin solution outside through the pipe wall to enable the thin solution to absorb heat to generate refrigerant vapor and become concentrated solution, and the concentrated solution is output from a concentrated solution outlet (through a heat exchanger and an absorber of a heat pipe heat pump unit) when accumulated to a certain height, and the refrigerant vapor is discharged from a vapor outlet (enters the condenser of the heat pipe heat pump unit). After lower-temperature flue gas from a heat pipe generator is input into a low-temperature flue gas cavity in the heat pipe water heater, the lower-temperature flue gas exchanges heat with the evaporation sections of all gravity type heat pipes in the heat pipe water heater, and water vapor in the flue gas condenses to release a large amount of latent heat, so that lower-temperature cold flue gas is finally formed and then is discharged to the outside; the medium in the evaporation section of each gravity type heat pipe in the heat pipe water heater absorbs the heat of the flue gas (mainly the latent heat of the flue gas) and then evaporates, the generated steam enters the condensation section and exchanges heat with the low-temperature water with the temperature of about 20 ℃ from the evaporator in the low-temperature water heat exchange cavity, the temperature is raised to about 30 ℃ after absorbing the heat, and the low-temperature water continuously enters the evaporator, so that the low-temperature heat source water circulation of the heat pipe heat pump unit is formed; and the vapor in the condensing section is condensed into liquid working medium, and the liquid working medium flows back to the evaporating section for recycling under the action of gravity. Through the reciprocating of the heat pipe generator and the heat pipe water heater, the heat exchange between the flue gas heat and low-temperature heat source water is realized, so that dry cold flue gas is formed, and the sensible heat and the latent heat in the flue gas are utilized, so that the heating grade and the waste heat utilization efficiency are greatly improved.
In summary, according to the invention, on one hand, gravity type heat pipes are distributed in the heat pipe generator of the heat pipe heat pump unit and the heat pipe water heater, and the gravity type heat pipes are combined to obtain cold flue gas with lower temperature, low-temperature heat source water with higher temperature if the temperature of the heat pipe generator is higher than that of the heat pipe generator (compared with other secondary heat exchange methods), so that the utilization rate of the latent heat of the flue gas is greatly improved, and the heating grade is greatly improved; the material of the evaporation section is designed into acid-resistant materials and acid-resistant coatings, so that the dew point corrosion problem caused by acid gas in the flue gas can be solved; on the other hand, compared with the existing flue gas tubular heat exchanger or flue gas plate heat exchanger, the heat pipe water heater has the advantages that the length of the evaporation section is larger than that of the condensation section, the heat exchange area can be greatly increased, the problem of low heat exchange coefficient of the flue gas side is solved, the flue gas with lower temperature is further obtained, the flue gas side resistance is small, smoke exhaust and normal combustion are not influenced, and the flue scale is not easy to block.

Claims (10)

1. The low-temperature flue gas efficient heat supply heat pump unit comprises a heat pipe type first heat pump unit and a heat pipe water heater, wherein the heat pipe type first heat pump unit comprises a heat pipe generator; the gravity type heat pipes are divided into an evaporation section and a condensation section; the evaporation section of the gravity type heat pipe in the heat pipe generator is used for carrying out heat exchange with low-temperature flue gas; the condensing section is used for carrying out heat exchange with dilute solution from an absorber of the heat pipe type first heat pump unit; the evaporation section of the gravity type heat pipe in the heat pipe water heater is used for carrying out heat exchange with the flue gas output by the heat pipe generator; the condensing section is used for carrying out heat exchange with a low-temperature water heat source from an evaporator of the heat pipe type first heat pump unit.
2. The low temperature flue gas efficient heat supply heat pump unit according to claim 1, wherein the length of the gravity type heat pipe evaporation section is greater than the length of the condensation section.
3. The low-temperature flue gas efficient heat supply heat pump unit according to claim 1, wherein the shell inner cavity of the heat pipe generator is divided into a flue gas cavity and a solution cavity by a partition plate, the evaporation section of the gravity type heat pipe is positioned in the flue gas cavity, the condensation section is positioned in the solution cavity, a liquid distribution device is arranged in the solution cavity, and the liquid distribution device is communicated with the dilute solution pipeline and the pump group.
4. The low-temperature flue gas efficient heat supply heat pump unit according to claim 3, wherein a flue gas cavity of the heat pipe generator is provided with a flue gas inlet and a flue gas outlet, the flue gas outlet is communicated with the heat pipe water heater, and the bottom of the flue gas cavity is provided with a condensate outlet; the solution cavity of the heat pipe generator is provided with a dilute solution inlet and a concentrated solution outlet, and the top of the solution cavity is provided with a water vapor outlet.
5. The low-temperature flue gas efficient heat supply heat pump unit according to claim 1, wherein the shell inner cavity of the heat pipe water heater is divided into a low-temperature flue gas cavity and a low-temperature water heat exchange cavity by a partition plate; the evaporating section of the gravity type heat pipe is positioned in the low-temperature smoke cavity, and the condensing section is positioned in the low-temperature water heat exchange cavity.
6. The low-temperature flue gas efficient heat supply heat pump unit according to claim 5, wherein the low-temperature flue gas cavity is provided with a low-temperature flue gas inlet and a cold flue gas outlet, the low-temperature flue gas inlet is communicated with a flue gas outlet pipeline of the heat pipe generator, and the bottom of the low-temperature flue gas cavity is provided with a condensate outlet; the low-temperature water heat exchange cavity is provided with a low-temperature water inlet and a low-temperature water outlet which are communicated with the evaporator pipeline.
7. The low-temperature flue gas efficient heat supply heat pump unit according to claim 1, wherein the diameter of the gravity type heat pipe is 5-200mm, the length of the evaporation section is 100-3000mm, and the length of the condensation section is 50-1000mm.
8. The low-temperature flue gas efficient heat supply heat pump unit according to claim 7, wherein the diameter of the gravity type heat pipe is 20-40mm, the length of the evaporation section is 500-1500mm, and the length of the condensation section is 100-500mm.
9. The low-temperature flue gas efficient heat supply heat pump unit according to claim 3 or 5, wherein the heat pipe type first heat pump unit is a heat pipe type flue gas type absorption type first heat pump unit; holes corresponding to the gravity type heat pipes in number are formed in the partition plate, and the gravity type heat pipes are connected with the holes in the partition plate in a sealing mode.
10. The low-temperature flue gas efficient heat supply heat pump unit according to claim 1, wherein the evaporation section is made of carbon steel, acid-resistant stainless steel, low alloy steel resistant to dew point corrosion or stainless steel resistant to dew point corrosion according to flue gas components and dew points, and the outer surface of the evaporation section is coated with a Teflon coating, an enamel coating or heat-resistant acid-resistant paint.
CN202310061845.0A 2023-01-13 2023-01-13 Low-temperature flue gas efficient heat supply heat pump unit Pending CN116123552A (en)

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CN202310061845.0A CN116123552A (en) 2023-01-13 2023-01-13 Low-temperature flue gas efficient heat supply heat pump unit

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Application Number Priority Date Filing Date Title
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CN116123552A true CN116123552A (en) 2023-05-16

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