CN115013998B

CN115013998B - Ammonia water absorption heat pump and control method thereof

Info

Publication number: CN115013998B
Application number: CN202210733101.4A
Authority: CN
Inventors: 姜培朋; 张丽红
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-06-27
Filing date: 2022-06-27
Publication date: 2023-05-12
Anticipated expiration: 2042-06-27
Also published as: CN115013998A

Abstract

The invention discloses an ammonia water absorption heat pump and a control method thereof, wherein the ammonia water absorption heat pump comprises a condenser, a generator, an evaporator, an absorber, a subcooler, a refrigerant solution heat exchanger, an absorbent solution heat exchanger, a refrigerant solution pump, an absorbent solution pump, a three-way regulating valve, a capacity regulating valve (or a burner), a refrigerant throttle valve, a solution throttle valve and a condensate heat exchanger (or a flue gas heat exchanger); by adding the circulation of the refrigerant solution, the condensation pressure is reduced, and the rectification process is simplified.

Description

Ammonia water absorption heat pump and control method thereof

Technical Field

The invention relates to an ammonia water absorption heat pump and a control method thereof, and belongs to the technical field of heat pumps.

Background

The lithium bromide absorption heat pump has been widely developed in recent ten years, and has been widely applied to urban central heating systems, such as heat source plants for recovering power generation by using lithium bromide absorption heat pump, chemical circulating water waste heat resources for saving energy or expanding heat supply capacity, and heat supply companies for increasing urban pipe network heat supply capacity by using large-temperature-difference lithium bromide heat exchanger sets. However, the specific thermophysical properties of the lithium bromide solution working fluid determine the limit of applicability of the lithium bromide absorption heat pump: 1. liquid waste heat resources with the temperature lower than 10 ℃ or gaseous waste heat resources with the temperature lower than 40 ℃ and low-level heat source resources such as ambient air, soil and the like cannot be utilized; 2. the temperature rise end difference (the difference between the temperature of the heat supply backwater entering the absorber and the temperature of the low-level heat source entering the evaporator) of the heat pump process is difficult to exceed 40 ℃. This has led to a further limitation in the popularization of lithium bromide absorption heat pumps.

Breaking through the temperature limit of the absorption heat pump to low-position heat source resources, the best method is to replace lithium bromide solution absorbing working medium. So far, the absorption working medium which is feasible in technical level and easy to commercialize only has ammonia-water working medium except lithium bromide solution.

The ammonia water absorption type refrigerator is used as the earliest refrigerator in history, and has been widely applied in refrigeration houses and chemical industry in nineties, but with the relief of the situation of shortage of power supply, and the reasons of lower thermal performance of ammonia-water working medium, toxic and flammable and explosive ammonia, the ammonia water absorption type refrigerator is gradually replaced by a Freon compression type refrigerating system with simpler structure, less investment and more convenient maintenance.

Of course, if an ammonia-water working medium is used for the heat pump system, the ammonia absorption refrigeration cycle operating parameters are not simply adjusted to the heat pump parameters because of the following limitations: 1. the water backwater temperature of the resident heating heat supply network is generally about 50 ℃, and for the central heating heat supply network, the backwater temperature is even higher than 60 ℃ and is far higher than the condensation temperature of the refrigeration working condition by 30-40 ℃; 2. the critical temperature of ammonia is only 133 ℃ and the critical pressure is 11.3MPa, so that the condensing pressure exceeds 2MPa when the heating temperature above 50 ℃ is obtained by condensing ammonia steam, and the manufacturing cost of a condenser, a generator and a rectifying system is greatly increased due to the excessive pressure; 3. ammonia is toxic, inflammable and explosive, and excessive condensing pressure also increases the risk of ammonia vapor leakage and increases the danger of the system; 4. the complex and heavy rectifying device in the ammonia absorption type refrigerating system is also a tripolite for commercialized popularization.

Therefore, if the ammonia-water working medium breaks through the applicable limit of the existing lithium bromide absorption heat pump, the problems of low heating temperature, high condensing pressure and rectification of the ammonia-water working medium in the heat pump cycle must be solved.

Disclosure of Invention

Aiming at the problems of high condensing pressure, low heating temperature and complex generator rectification faced by the existing heat pump process of an ammonia water absorption type system, the invention provides a solution, and particularly relates to an ammonia water absorption type heat pump and a control method thereof.

In order to solve the problems, the invention adopts the following technical scheme: an ammonia water absorption heat pump comprises a condenser, a generator, an evaporator, an absorber, a subcooler, a refrigerant solution heat exchanger, an absorbent solution heat exchanger, a refrigerant solution pump, an absorbent solution pump, a three-way regulating valve, a capacity regulating valve (or a burner), a refrigerant throttle valve, a solution throttle valve and a condensate heat exchanger (or a flue gas heat exchanger).

Further, the above-mentioned equipment structure constitutes as follows:

and (3) a condenser:

the device consists of a condenser ammonia vapor inlet, a condenser cooling water outlet, a condenser refrigerant solution inlet, a condenser refrigerant solution outlet, a cooling water connecting pipe, a condenser refrigerant solution storage cavity, an ammonia vapor condensation section, a condenser refrigerant solution liquid distribution pipe, a condenser refrigerant solution liquid distributor and an ammonia vapor primary cooling section;

The generator comprises:

the device consists of a generator ammonia steam outlet, a rectifying section, a generator concentrated solution inlet, a solution regenerating section, a condensate outlet (or a flue gas outlet), a generator dilute solution outlet, a generator dilute solution storage cavity, a driving steam inlet (or a driving flue gas inlet), a generator liquid distributor, a generator refrigerant solution inlet and a generator refrigerant solution sprayer;

an absorber:

the device consists of an absorber dilute solution inlet, an absorber concentrated solution outlet, an absorber cooling water inlet, an absorber cooling water outlet, an absorber ammonia steam inlet, an absorber concentrated solution storage cavity, a solution absorption section, an absorber solution distributor and an absorber solution distribution pipe;

an evaporator:

the structure is different according to the type of the low-level heat source;

when the low-level heat source is liquid or closed gas, the evaporator is of a flooded structure and consists of an ammonia vapor outlet of the flooded evaporator, a refrigerant solution inlet of the flooded evaporator, a refrigerant solution outlet of the flooded evaporator, a low-level heat source inlet, a low-level heat source outlet and an evaporation section;

when the low-level heat source is ambient air, the evaporator is of a surface cooling structure and consists of a surface cooling evaporator ammonia steam outlet, a surface cooling evaporator refrigerant solution inlet, a surface cooling evaporator refrigerant solution outlet, a fan, a liquid separation pipe, a fin pipe, a steam drum, a frost melting control valve and an electric heating wire;

Subcooler:

the device comprises a subcooler ammonia steam outlet, a hot side refrigerant solution inlet, a cold side refrigerant solution outlet, a subcooler heat exchange section, a hot side refrigerant solution outlet and a cold side refrigerant solution inlet; the refrigerant solution coming out of the evaporator (cold side) goes to the tube side and the refrigerant solution coming out of the condenser (hot side) goes to the shell side;

refrigerant solution heat exchanger:

the plate heat exchanger is used for exchanging heat between the refrigerant solution from the evaporator and the refrigerant solution from the condenser;

absorbent solution heat exchanger:

a plate heat exchanger for exchanging heat between the absorbent solution from the absorber and the absorbent solution from the generator;

condensate heat exchanger (or flue gas heat exchanger):

a shell-and-tube heat exchanger, wherein the absorbent solution from the absorber exchanges heat with the driving steam condensate (or smoke exhaust) from the generator;

further, the above-mentioned equipment connection mode is as follows:

connection between condenser and evaporator:

the refrigerant solution outlet of the condenser is connected with the refrigerant solution inlet of the evaporator through a pipeline, a refrigerant solution heat exchanger, a subcooler and a throttle valve; the refrigerant solution outlet of the evaporator is connected with the inlet C of the three-way regulating valve through a pipeline by a cooler, a refrigerant solution pump and a refrigerant solution heat exchanger; the outlet A of the three-way regulating valve is connected with the refrigerant solution inlet of the condenser, and the outlet B of the three-way regulating valve is connected with the refrigerant solution inlet of the generator to complete the circulation of the refrigerant solution;

Connection of generator and absorber:

the dilute solution outlet of the generator is connected with the dilute solution inlet of the absorber through a pipeline by an absorbent solution heat exchanger and a throttle valve; the concentrated solution outlet of the absorber is divided into two parts after being pumped by the absorbent solution pump, the majority of the concentrated solution outlet is heated by the absorbent solution heat exchanger, the minority of the concentrated solution outlet is heated by the condensate heat exchanger (or the flue gas heat exchanger), and the concentrated solution outlet is connected with the concentrated solution inlet of the generator through a pipeline after being mixed, so that the circulation of the absorbent solution is completed;

connection of the generator to the condenser:

the ammonia steam outlet of the generator is connected with the ammonia steam inlet of the condenser;

connection of evaporator to absorber:

the evaporator ammonia steam outlet is connected with the absorber ammonia steam inlet;

connection of low-level heat source and evaporator:

when the low-level heat source is liquid or closed gas, the low-level heat source supply pipeline is connected with the low-level heat source inlet of the evaporator, and the return pipeline is connected with the low-level heat source outlet of the evaporator, so that the low-level heat source flow is completed; when the low-level heat source is ambient air, the fan ventilates to complete the flow of the low-level heat source;

the connection of the cooling water with the absorber and the condenser:

the cooling water supply is connected with a condenser cooling water inlet, a condenser cooling water outlet is connected with an absorber cooling water inlet, and then the absorber cooling water outlet is connected with cooling water backwater to complete a cooling water flow;

Connection of the driving heat source and the generator:

when the driving source is steam, the driving steam is connected with a driving steam inlet of the generator through the capacity regulating valve, a condensed water outlet of the generator is connected with a condensed water inlet of the condensed water heat exchanger, and a condensed water outlet of the condensed water heat exchanger is connected with a condensed water drainage pipeline to complete the driving process; when the driving source is fuel gas, the driving fuel gas burner is connected with a generator driving flue gas inlet, a generator flue gas outlet is connected with a flue gas inlet of the flue gas heat exchanger, and a flue gas outlet chimney of the flue gas heat exchanger is connected to complete the driving process;

further, the components of the apparatus are constructed and made of the following materials:

and (3) a condenser:

the structure of the condenser is as follows from top to bottom: the device comprises a condenser ammonia steam inlet, an ammonia steam primary cooling section, a condenser cooling water outlet, a cooling water connecting pipe, a condenser refrigerant solution inlet, a condenser refrigerant solution distributor, a condenser liquid distribution pipe, an ammonia steam condensing section, a condenser cooling water inlet, a condenser refrigerant solution storage cavity and a condenser refrigerant solution outlet;

the ammonia vapor inlet of the condenser is opened on the upper end closure of the condenser; the condenser refrigerant solution storage cavity is formed by adding a section of straight pipe to the lower end socket of the condenser, and the volume size is designed according to the whole heat pump circulation working condition; the condenser coolant solution outlet is arranged at the lower part of the coolant solution storage cavity;

The primary cooling section of ammonia vapor is of a shell-and-tube structure, ammonia vapor and condensate (both concurrent flow) are moved in the heat transfer tube of the primary cooling section, and cooling water is moved in the shell pass of the heat transfer tube of the primary cooling section; the primary cooling section heat transfer pipe is made of 0Cr18Ni9 or high-quality carbon steel and is connected to the pipe plate by welding;

the ammonia vapor refrigerant condensing section is of a shell-and-tube structure, ammonia vapor and refrigerant solution (both flow along) are moved in the heat transfer tube of the condensing section, and cooling water is moved in the shell side of the heat transfer tube of the condensing section, and high-quality carbon steel is adopted; the condensing section heat transfer tube is made of 0Cr18Ni9 or high-quality carbon steel and is welded on the tube plate;

the condenser liquid distributor consists of a calandria, dropping holes are drilled on the calandria, the condenser liquid distributor has the function of uniformly distributing liquid, the large deviation of the distribution of the solution in the vessel is avoided, the condenser liquid distributor is connected with a condenser coolant solution inlet, and the condenser liquid distributor is made of 0Cr18Ni9 or high-quality carbon steel;

the condenser refrigerant solution liquid distribution pipe is a hollow pipe, ammonia vapor is arranged in the middle, refrigerant solution is arranged on the inner side of the pipe wall, and the condenser refrigerant liquid distribution pipe is arranged at the upper port of the ammonia vapor refrigerant condensation section heat transfer pipe and is divided into three sections: the upper end is a liquid inlet section, and a notch (which is adjusted according to the pipe diameter and the liquid level of the refrigerant) with the length of 30-50 mm and the width of 1-3 mm is formed along the periphery of the pipe at intervals of 15-30 degrees; the middle part is a liquid homogenizing section, which has the function of uniformly distributing the refrigerant solution flowing into the notch on the whole pipe wall, and the length is 40-100 mm; the lower end is an expansion joint section which is connected in the tube plate heat transfer tube hole of the ammonia vapor refrigerant condensing section through expansion; the condenser liquid distribution pipe is made of 0Cr18Ni9 or high-quality carbon steel;

The condenser shell is made of high-quality carbon steel;

the generator comprises:

the structure of the generator is that from top to bottom respectively: the device comprises a generator ammonia steam outlet, a generator refrigerant solution inlet, a generator refrigerant solution sprayer, a rectifying section, a generator concentrated solution inlet, a generator concentrated solution distributor, a solution regeneration section, a driving steam inlet (or driving gas inlet), a condensate outlet (or flue gas outlet), a generator dilute solution storage cavity and a generator dilute solution outlet;

the ammonia vapor outlet of the generator is arranged on the upper end socket of the generator, and a liquid baffle is arranged in the ammonia vapor outlet of the generator; the generator dilute solution storage cavity is formed by adding a straight pipe section to the lower end socket of the generator, and the volume size is determined according to the design of the whole heat pump circulation working condition; the generator dilute solution outlet is arranged at the lower part of the generator dilute solution storage cavity;

the generator coolant solution sprayer consists of a calandria, wherein spray heads are arranged on the calandria, the spray heads are spiral stainless steel spray heads, and the number of the spray heads is designed in such a way that coolant solution can be uniformly sprayed on baffle plates of a rectifying section; the generator coolant solution sprayer is made of 0Cr18Ni9 or high-quality carbon steel;

the rectifying section consists of herringbone baffle plates, the space between the baffle plates is 1-3 mm, the height is 200-400 mm, the rectifying section can be arranged in multiple layers, and the material is 0Cr18Ni9;

The generator solution distributor has the same structure as the condenser distributor, and consists of a calandria, wherein the calandria is drilled with liquid dropping holes and is made of 0Cr18Ni9 or high-quality carbon steel;

the solution regeneration section is of a shell structure, solution and boiling ammonia steam (countercurrent flow of the solution and the boiling ammonia steam) are carried out in a heat transfer pipe of the regeneration section, steam and condensed water (or flue gas) thereof are carried out in the shell of the heat transfer pipe, and the heat transfer pipe of the regeneration section is made of 00Cr22Ni5Mo3N or high-quality carbon steel material and is welded on a pipe plate;

the generator shell is made of high-quality carbon steel;

an absorber:

the absorber comprises an absorber ammonia steam inlet, an absorber dilute solution distributor, an absorber liquid distribution pipe, a solution absorption section, an absorber cooling water outlet, an absorber cooling water inlet and an absorber concentrated solution outlet from top to bottom in sequence;

the ammonia vapor inlet of the absorber is opened at the upper end socket of the absorber; the concentrated solution outlet of the absorber is arranged on the lower seal head of the absorber;

the absorber dilute solution distributor and the condenser are identical in structure and consist of a calandria, and drip holes are drilled on the calandria;

the absorber liquid distribution pipe and the condenser liquid distribution pipe have the same structure and material, are hollow pipes, are filled with ammonia vapor in the middle, are filled with absorbent solution in the inner side of the pipe wall, and are arranged at the upper port of the heat transfer pipe of the solution absorption section;

The absorber solution absorption section is of a tube shell structure, solution and ammonia vapor (both flow along) flow in a heat transfer tube of the absorption section, cooling water flows in the shell pass of the heat transfer tube of the absorption section, and the heat transfer tube of the absorption section is made of 0Cr18Ni9 or high-quality carbon steel materials and is welded on a tube plate;

the absorber shell is made of high-quality carbon steel;

an evaporator:

when the low-level heat source is liquid or closed gas, the evaporator is of a flooded type structure, and is an ammonia vapor outlet, a refrigerant solution outlet, an evaporation section, a low-level heat source inlet, a low-level heat source outlet and a refrigerant solution inlet of the flooded type evaporator from top to bottom; the ammonia vapor outlet of the flooded evaporator is arranged on the upper end enclosure of the evaporator, and a liquid baffle is arranged in the evaporator; the evaporation section is of a shell structure, a refrigerant solution and boiling ammonia vapor (both flow along) flow in a heat transfer pipe of the evaporation section, a low-level heat source flows in the shell of the heat transfer pipe of the evaporation section, and the heat transfer pipe is made of 0Cr18Ni9 or high-quality carbon steel and is welded on a pipe plate;

when the low-level heat source is ambient air, the evaporator is of a surface-cooling structure, and the top-down part is respectively provided with a surface-cooling evaporator ammonia steam outlet, a frost control valve, a steam drum, a surface-cooling evaporator refrigerant solution outlet, a fin tube, a fan, a liquid separation tube and a surface-cooling evaporator refrigerant solution inlet; the ammonia steam outlet of the surface-cooling evaporator is arranged on the evaporator steam drum, and a liquid baffle is arranged in the evaporator steam drum; the fin tube is filled with refrigerant solution and boiling ammonia vapor (both flow along) and air is filled in gaps between the outer fins of the heat transfer tube, the fin tube is made of 0Cr18Ni9 or high-quality carbon steel, and the fins are made of aluminum or 0Cr18Ni9 and welded on the heat transfer tube;

Subcooler:

the structure of the subcooler is respectively provided with a subcooler ammonia steam outlet, a cold side refrigerant solution inlet, a subcooler heat exchange section, a hot side refrigerant solution outlet, a hot side refrigerant solution inlet and a cold side refrigerant solution outlet from top to bottom;

the ammonia vapor outlet of the subcooler is arranged on the upper end socket of the subcooler, and a liquid baffle is arranged in the ammonia vapor outlet;

the heat exchange section of the subcooler is of a shell-and-tube structure, the heat transfer pipe of the heat exchange section is internally provided with an evaporator refrigerant solution and boiling ammonia steam (in countercurrent), the shell side of the heat transfer pipe of the heat exchange section is provided with a condenser refrigerant solution, and the heat transfer pipe of the heat exchange section is made of 0Cr18Ni9 or high-quality carbon steel material and is connected to a pipe plate in an expansion way or welded way;

refrigerant solution heat exchanger:

the plate heat exchanger is made of 0Cr18Ni9 or 022Cr17Ni12Mo2;

absorbent solution heat exchanger:

the plate heat exchanger is made of 0Cr18Ni9 or 022Cr17Ni12Mo2;

further, the medium flow in the device is as follows:

in the evaporator, the refrigerant solution from the condenser is cooled by the cooler, enters into the heat transfer tube (or fin tube) of the evaporation section from the bottom of the evaporator, absorbs the heat of the low-level heat source at the shell side (or fin side) while boiling to release ammonia steam, and finally flows out from the upper part (or steam drum) of the evaporator through the refrigerant solution outlet; when the low-level heat source is liquid or airtight gas, the low-level heat source medium enters from the upper part of the shell side of the evaporation section, and flows out from the low-level heat source outlet at the lower part of the shell side of the evaporation section after being baffled in the evaporation section; when the low-level heat source is ambient air, the air enters from the lower part of the fin tube through the fan, and flows out from the upper part of the fin tube;

In the condenser, ammonia steam from the generator enters an ammonia steam primary cooling section from the upper part, cooling is carried out by cooling water, condensate liquid is generated to flow downwards along with the ammonia steam in a heat transfer pipe, and the condensate liquid is dripped into a condensing section; the refrigerant solution is evenly dripped into the condensation section through the refrigerant solution inlet of the condenser and the refrigerant solution distributor, is mixed with the condensate of the primary ammonia vapor cooling section, and enters the ammonia vapor condensation section heat transfer pipe together to continuously absorb the ammonia vapor; in the ammonia vapor condensing section, ammonia vapor is absorbed by the refrigerant solution, the heat is released to heat the cooling water at the shell side, the refrigerant solution with the concentration of the absorbed ammonia vapor becoming concentrated is collected in the refrigerant solution storage cavity, and then is discharged from the refrigerant solution outlet at the bottom of the storage cavity; cooling water enters from the lower part of the shell side of the ammonia vapor condensation section, is baffled in the ammonia vapor condensation section, cools ammonia vapor and refrigerant solution in the heat transfer pipe, then flows out from the upper part of the shell side of the ammonia vapor condensation section, passes through the cooling water connecting pipe, enters the ammonia vapor primary cooling section from the lower part of the shell side of the ammonia vapor primary cooling section, and then flows out from the upper part of the shell side of the ammonia vapor primary cooling section;

in the generator, the concentrated solution from the absorber enters a regeneration section of the generator from a concentrated solution inlet and a concentrated solution distributor, ammonia steam is separated out for regeneration under the heating of driving steam (or flue gas), the concentrated solution flows along a heat transfer pipe from top to bottom, the separated ammonia steam flows along the heat transfer pipe from bottom to top, and finally the concentrated solution is regenerated to be changed into a dilute solution to enter a dilute solution storage cavity; the ammonia steam generated in the regeneration section is washed by the concentrated solution and enters the rectification section, the ammonia steam and the refrigerant solution are subjected to steam stripping heat exchange in the rectification section, the ammonia steam is rectified and discharged from an ammonia steam outlet, the concentration of the refrigerant solution is reduced by heat and mass exchange concentration, and finally the refrigerant solution is collected into the concentrated solution and enters the regeneration section; the refrigerant solution in the rectifying section comes from a three-way regulating valve, and is sprayed into the rectifying section; driving steam to enter the generator from the upper part of the shell side of the regeneration section, heating the solution of the regeneration section through a heat transfer pipe of the regeneration section, changing the solution into condensed water, and discharging the condensed water out of the generator through a condensed water outlet at the lower part of the shell side of the regeneration section; in the case that the driving source is fuel gas, the fuel gas is driven to burn through a burner to generate high-temperature flue gas, the high-temperature flue gas enters the generator from the upper part of the shell side of the regeneration section, the solution of the regeneration section is heated through a heat transfer pipe, cooled to a reasonable temperature, and then discharged out of the generator through a flue gas outlet at the lower part of the shell side of the regeneration section;

In the absorber, ammonia vapor from the evaporator enters from the lower part, enters the absorption section heat transfer tube through the absorption section heat transfer tube, and flows from bottom to top to meet the requirement of absorption of solution at the lower part of the absorption section. The dilute solution from the generator enters the absorber from the dilute solution inlet and the dilute solution distributor, enters the heat transfer pipe through the liquid distribution pipe, transfers the absorption heat to the cooling water at the shell side while the concentration of the absorbed ammonia vapor is increased, and then is collected at the lower end enclosure of the bottom of the absorber and is discharged from the concentrated solution outlet; cooling water enters from a cooling water inlet at the lower part of the shell side of the absorption section, and flows out from a cooling water outlet at the upper part of the shell side of the absorption section after being baffled in the absorption section;

in the subcooler, the refrigerant solution from the evaporator enters from the upper part of the shell side and flows out from the lower part of the shell side; the refrigerant solution from the condenser enters from the lower part of the tube side, flows out from the upper part of the tube side and then enters the shell side of the evaporator; the evaporator refrigerant solution absorbs heat from the condenser refrigerant solution by boiling, further subcooling it.

Further, the above-described equipment installation requirements are as follows:

the condenser, the generator, the absorber, the evaporator and the subcooler are all vertically arranged, and the deviation of the perpendicularity is not more than 1/1000.

Further, the method for greatly reducing the condensation pressure of ammonia vapor in the condenser and simplifying the rectification process of the generator by the ammonia water absorption heat pump is realized by spraying a refrigerant solution to the condenser and the generator, and comprises the following steps:

1) Setting a refrigerant solution pump, and extracting refrigerant solution tail liquid with the concentration of 60-90% after evaporation of an evaporator;

2) Delivering a refrigerant solution tail liquid to a condenser through a refrigerant solution pump to assist ammonia vapor condensation, and reducing condensation pressure;

3) Spraying a small amount of refrigerant solution tail liquid to the generator through refrigerant solution circulation, and stripping ammonia steam at the outlet of the generator, so that the rectification process is simplified;

the existence of the tail liquid of the refrigerant solution can greatly reduce the condensing pressure of the condenser. For example, a temperature of 70℃corresponds to a saturation pressure of about 3.3MPa for 100% ammonia vapor, and a 63.5% (mole fraction) refrigerant solution corresponds to a saturation pressure of only 1.8MPa. After 63.5% (mole fraction) of the refrigerant solution was fed to the condenser, the condenser pressure was set at 1.8MPa to complete liquefaction and condensation of ammonia vapor due to the presence of the refrigerant solution;

in the ammonia water absorption refrigeration cycle, the concentration of ammonia vapor entering a condenser is generally required to be more than 99.8%, and a complicated rectifying device is required to be arranged at an ammonia vapor outlet of the generator to achieve the concentration;

Still taking the above condensing temperature of 70 ℃ as an example, under the auxiliary condition of the tail liquid of the refrigerant solution, even if the concentration of ammonia vapor is reduced to 80% (mole fraction), the condensing process of the condenser can be completed, and the whole ammonia water absorption thermodynamic cycle including the evaporator, the absorber and the generator is not affected. The existence of the refrigerant solution greatly reduces the ammonia vapor concentration requirement of the condenser on the generator, greatly simplifies the rectifying process at the generator side and does not need to be provided with a special refining device;

this allows a large amount of water working medium to flow from the generator-absorber side to the condenser-evaporator side as the concentration of ammonia vapor entering the condenser is reduced. For this purpose, the generator introduces a coolant solution spray link. In the link, firstly, the ammonia vapor can be brought into the water working medium at the condenser-evaporator side to be fed back to the generator-absorber side, so that the balance of the water working medium in the whole system flow is realized, and secondly, the refrigerant solution is sprayed to strip and rectify the ammonia vapor of the generator, so that the concentration of the ammonia vapor entering the condenser is improved.

Further, the capacity adjustment method of the ammonia water absorption heat pump load comprises the following steps of taking the outlet temperature of the cooling water of the absorber as a control target, and adopting a PID mode to realize the capacity adjustment by controlling and driving the opening of the combustor.

Further, the condensing pressure self-adaptive adjusting method of the ammonia water absorption heat pump comprises the following steps:

1) Detecting the pressure P2 of the condenser, and detecting the temperature T of ammonia steam entering the condenser;

2) Setting a condenser pressure control value P0, detecting the condenser pressure P, detecting the temperature T of ammonia steam entering the condenser, and regulating the opening of the side B of a three-way regulating valve in a PID mode by taking the condensing pressure P0 as a control target to regulate the tail liquid amount of the refrigerant solution entering the generator;

3) When the pressure P of the condenser is higher than P0, regulating and reducing the opening of the outlet B side of the three-way regulating valve to reduce the tail liquid of the refrigerant solution entering the generator; when the pressure P of the condenser is lower than P0, the opening of the outlet B side of the three-way regulating valve is regulated and controlled to be large, so that the tail liquid of the refrigerant solution entering the generator is increased;

4) When the opening of the outlet B side of the regulating three-way regulating valve is regulated to the maximum, the pressure P of the condenser is still lower than P0 and is maintained for 20 seconds, the concentration M3 of ammonia steam is calculated according to an ammonia-water binary system state equation through the condensing pressure P and the ammonia steam temperature T, and the ammonia steam concentration M3 is taken as a regulating target;

5) If the calculated ammonia vapor concentration M3 is higher than 99.5%, regulating and controlling the opening degree of the outlet B side of the three-way regulating valve to be reduced, so that the tail liquid of the refrigerant solution entering the generator is reduced; if the ammonia vapor concentration M3 is lower than 99.0%, regulating and controlling the opening of the outlet B side of the three-way regulating valve to increase so as to increase the tail liquid of the refrigerant solution entering the generator;

6) When the condenser pressure P reaches P0, automatically switching to the regulation taking the condensing pressure P0 as a control target;

7) If the tail liquid of the refrigerant solution entering the generator is reduced to 0 (the opening of the outlet B side of the three-way regulating valve is 0), and the pressure P of the condenser is still higher than P0, immediately implementing capacity regulation limitation, and rapidly limiting the opening of the capacity regulating valve to be less than 30%; if the condenser pressure P is still higher than P0 at this time, the capacity regulating valve is closed completely, and the capacity regulating valve is opened again after the condensing pressure P is reduced to 0.8 times of P0;

8) During the regulation, if a condensation pressure P greater than 1.2 times P0 occurs, the capacity control valve is immediately closed.

Further, the self-adaptive adjusting method for the ammonia thermodynamic cycle caused by the fluctuation of the driving steam pressure comprises the following steps:

the low-level heat source, the temperature of the cooling water inlet and outlet and the regulation process brought by driving steam pressure fluctuation comprise the regulation of a refrigerant throttle valve, the regulation of a solution throttle valve, the regulation of an absorbent solution pump and the regulation of the refrigerant solution pump;

wherein, the refrigerant throttle valve is adjusted, includes the following steps:

setting an evaporator liquid level control value F10, detecting the evaporator liquid level F1, and controlling the opening degree of the evaporator liquid level F1 in a PID mode to adjust the flow rate of the refrigerant solution entering the evaporator so as to realize the thermodynamic cycle adjustment of ammonia water;

Solution throttle valve adjustment, comprising the steps of:

setting a generator liquid level control value F20, detecting a generator liquid level F2, controlling the opening degree of the generator liquid level F2 in a PID mode, and adjusting the flow rate of the solution entering the absorber to realize the thermodynamic cycle adjustment of ammonia water;

the absorbent solution pump adjustment comprises the following steps:

the absorber solution pump is used for adjusting, the operating frequency of the absorber solution pump is adjusted according to the concentration difference of the ammonia water solution at the outlet of the generator and the outlet of the absorber, the flow of the solution entering the generator is adjusted, and the thermodynamic cycle adjustment of the ammonia water is realized; the concentration M1 of the ammonia water solution at the outlet of the generator and the concentration M2 of the ammonia water solution at the outlet of the absorber satisfy the following conditions: 3 < M1/(M2-M1) < 5.

The refrigerant solution pump adjustment comprises the following steps:

and the fixed frequency operation is performed under the normal working condition.

When the ambient air is used as a low-level heat source, the evaporation section is of a finned tube structure, and air is taken away from gaps between fins outside the heat transfer tube. When the temperature of the heat transfer tube fins is lower than 0 ℃, water vapor in the air is sublimated on the fins to form frost, and when the thickness of the frost layer is to a certain degree, the heat exchange effect of the evaporator is greatly reduced, and at the moment, the evaporator needs to be defrosted.

Further, the defrosting method of the ammonia water absorption heat pump evaporator comprises the following steps:

An electric heating scheme is adopted, namely an electric heating wire is arranged on a liquid separation pipe;

judging the end difference of the ambient temperature and the evaporating temperature, if the end difference exceeds a set value, starting a defrosting process, wherein the specific process is as follows:

1) Closing the capacity adjusting valve;

2) Stopping the absorbent solution pump, the refrigerant solution pump and the evaporator fan;

3) Closing the frost melting control valve and the refrigerant throttle valve;

4) Starting electric heating;

5) Monitoring the pressure of the evaporator and the temperature of the liquid separation pipe, and stopping electric heating after the pressure reaches 0.6MPa and 10 ℃;

6) After the electric heating is stopped, the temperature of the fin tube is monitored, and if the temperature reaches 5 ℃, the melting of the frost is finished.

7) Opening a frost melting control valve and a refrigerant throttle valve, and starting an absorbent solution pump, a refrigerant solution pump and an evaporator fan;

8) And opening the capacity regulating valve and starting the heat pump.

Through the facilities and the technical means, the ammonia water absorption heat pump and the control method thereof have the beneficial effects that: 1. the temperature limit of the lithium bromide-water absorption type working medium on the low-position heat source selection is broken through by the ammonia-water absorption type working medium pair, so that the heat extraction of the ambient air with the temperature lower than-10 ℃ can be realized; 2. the temperature rising end difference (the difference between the temperature of cooling water entering the condenser and the temperature of a low-level heat source exiting the evaporator) in the heating process of the heat pump can reach more than 60 ℃, so that the application range of hot water of the heat pump is greatly improved, and the limit of the working capacity of the current lithium bromide absorption heat pump is broken through; 3. the condenser and the evaporator are additionally arranged to circulate the refrigerant solution, so that the condensing pressure (generating pressure) is greatly reduced, and the heating temperature above 70 ℃ can be realized within 2 MPa; 4. the rectification process of the generator is realized by using the refrigerant circulating rich concentrated ammonia water, and the generator rectification section formed by the herringbone baffle plates has very simple structure, thereby greatly simplifying the structure of the generator, greatly reducing the manufacturing cost of the generator and improving the safety of the ammonia water absorption heat pump.

The invention will be further described with reference to the drawings and examples.

Drawings

FIG. 1 is a schematic diagram of the present invention, wherein FIG. 1-A is a schematic diagram when the low-level heat source is liquid or closed gas, and FIG. 1-B is a schematic diagram when the low-level heat source is ambient air;

FIG. 2 is a schematic view of the condenser structure (in cross section) of the present invention;

FIG. 3 is a schematic view (in cross section) of the generator of the present invention;

FIG. 4 is a schematic view of the liquid distribution pipe structure (cross section) of the condenser and absorber of the present invention;

FIG. 5 is a schematic view (in cross section) of an absorber structure of the present invention;

FIG. 6 is a schematic view of the evaporator according to the present invention, wherein FIG. 6-A is a schematic view of the flooded evaporator according to the present invention (in cross section) when the low-level heat source is liquid, and FIG. 6-B is a schematic view of the surface-cooled evaporator according to the present invention when air is used as the low-level heat source (in cross section);

FIG. 7 is a schematic view of the subcooler structure (in cross section) of the present invention;

fig. 8 is a control IP diagram (blue-based in fig. 1-a) of the present invention.

In fig. 1, a condenser, 2, a safety valve, 3, a three-way regulating valve, 4, a driving steam (or driving fuel gas), 5, a capacity regulating valve (or burner), 6, a generator, 7, a condensate heat exchanger (or flue gas heat exchanger), 8, a condensate drainage pipeline (or chimney), 9, an absorbent solution heat exchanger, 10, cooling water backwater, 11, an absorbent solution pump, 12, a solution throttle valve, 13, an absorber, 14, a refrigerant solution pump, 15, a subcooler, 16, a refrigerant throttle valve, 17, a low-level heat source return pipeline, 18, a low-level heat source supply pipeline, 19, an evaporator, 19A-flooded evaporator, and 19-B condensing evaporator; 20. a refrigerant solution heat exchanger 21, a cooling water supply;

In FIG. 2, 1-1 parts of condenser ammonia vapor inlets, 1-2 parts of condenser cooling water outlets, 1-3 parts of condenser refrigerant solution inlets, 1-4 parts of cooling water connecting pipes, 1-5 parts of condenser refrigerant solution storage cavities, 1-6 parts of condenser refrigerant solution outlets, 1-7 parts of condenser cooling water inlets, 1-8 parts of ammonia vapor condensing sections, 1-8-1 parts of condensing section heat transfer pipes, 1-8-2 parts of condensing section pipe plates, 1-9 parts of condenser liquid distribution pipes, 1-10 parts of condenser refrigerant solution distributor, 1-11 parts of ammonia vapor primary cooling sections, 1-11-1 parts of primary cooling section heat transfer pipes, 1-11-2 parts of primary cooling section pipe plates;

in FIG. 3, 6-1, generator ammonia vapor outlet, 6-2, rectifying section, 6-3, generator concentrated solution inlet, 6-4, solution regeneration section, 6-4-1, regeneration section heat transfer tube, 6-4-2, regeneration section tube plate, 6-5, condensate outlet (or flue gas outlet), 6-6, generator dilute solution outlet, 6-7, generator dilute solution storage cavity, 6-8, drive vapor inlet (or drive flue gas inlet), 6-9, generator liquid distributor, 6-10, generator refrigerant solution inlet, 6-11, generator refrigerant solution spray;

in FIG. 4, 1-9-a, liquid inlet section, 1-9-b, liquid homogenizing section, 1-9-c and expansion joint section;

in FIG. 5, 13-1, absorber ammonia vapor inlet, 13-2, absorber dilute solution inlet, 13-3, absorber cooling water outlet, 13-4, absorber concentrated solution outlet, 13-5, absorber solution distributor, 13-6, absorber distributor, 13-7, solution absorption section, 13-7-1, solution absorption section heat transfer tube, 13-7-2, solution absorption section tube sheet, 13-8, absorber cooling water inlet, 13-9, absorber concentrated solution storage chamber;

In FIG. 6-a, 19-A-1, flooded evaporator ammonia vapor outlet, 19-A-2, flooded evaporator refrigerant solution outlet, 19-A-3, low heat source outlet, 19-A-4, flooded evaporator refrigerant solution inlet, 19-A-5, flooded evaporator end, 19-A-5-1, evaporator end heat transfer tubes, 19-A-5-2, evaporator end tube sheets, 19-A-6, low heat source inlet;

in FIG. 6-B, 19-B-1, surface-cooled evaporator ammonia vapor outlet, 19-B-2, surface-cooled evaporator coolant solution outlet, 19-B-3, blower, 19-B-4, surface-cooled evaporator coolant solution inlet, 19-B-5, liquid dividing tube, 19-B-6, finned tube, 19-B-7, steam drum, 19-B-8, frost control valve, 19-B-9, electric heating wire;

in FIG. 7, 15-1, subcooler ammonia vapor outlet, 15-2, hot side refrigerant solution inlet, 15-3, cold side refrigerant solution outlet, 15-4, subcooler heat exchange section, 15-4-1, heat exchange section heat transfer tubes, 15-4-2, heat exchange section tube sheets, 15-5, hot side refrigerant solution outlet, 15-6, cold side refrigerant solution inlet;

in fig. 8, T1, cooling water condenser inlet temperature, T2 cooling water condenser middle temperature, T3 cooling water condenser outlet temperature, T4, cooling water absorber outlet temperature, T5, low temperature source water evaporator inlet temperature (ambient air temperature), T6 low temperature source water evaporator outlet temperature, T7, drive steam generator inlet temperature, T8 drive steam condensate water discharge temperature, T9, evaporator outlet ammonia vapor temperature, T10, evaporator reservoir temperature, T11, subcooler refrigerant ammonia liquid outlet temperature, T12, condenser refrigerant ammonia liquid inlet temperature, T13, condenser refrigerant ammonia liquid outlet temperature, T14, subcooler refrigerant ammonia liquid inlet temperature, T15, condenser ammonia vapor inlet temperature, T16, generator dilute ammonia liquid outlet temperature, T17, absorber dilute solution inlet temperature, T18, absorber concentrated solution outlet temperature, T19, absorber solution heat exchanger outlet temperature, T20, generator concentrated solution inlet temperature, P1, drive steam generator inlet pressure, P2, pressure generator (P3, pressure generator concentrated solution outlet pressure, M, pressure generator concentrated solution outlet pressure M, M2, evaporator concentration M, concentration M1, concentration of the absorber concentration M2, concentration of the absorber concentration M, concentration M2, concentration of the absorber concentration M).

Detailed Description

Some specific embodiments of the invention will be described in detail below by way of example and not by way of limitation with reference to the accompanying drawings. The same reference numbers in the above figures identify the same or similar components or portions, and it will be understood by those skilled in the art that the figures are not necessarily drawn to scale.

1-8, an ammonia absorption heat pump is composed of a condenser 1, a generator 6, an evaporator 19, an absorber 13, a subcooler 15, a refrigerant solution heat exchanger 20, an absorbent solution heat exchanger 9, a refrigerant solution pump 14, an absorbent solution pump 11, a three-way regulating valve 3, a capacity regulating valve (or burner) 5, a refrigerant throttle valve 16, a solution throttle valve 12, a condensate heat exchanger (or flue gas heat exchanger) 7, and a safety valve 2.

The evaporator 19 may be one of a flooded evaporator 19A or a condensing evaporator 19-B.

Wherein, the refrigerant solution outlet 1-6 of the condenser 1 is connected with the refrigerant solution inlet 19-A-4 of the flooded evaporator (or the refrigerant solution inlet 19-B-4 of the surface-cooled evaporator) through a pipeline, a refrigerant solution heat exchanger 20, a subcooler 15 and a refrigerant throttle valve 16; the refrigerant solution outlet 19-A-2 of the flooded evaporator (or the refrigerant solution outlet 19-B-2 of the surface-cooled evaporator) is connected with the inlet of the three-way regulating valve 3 through a pipeline, a cooler 15, a refrigerant solution pump 14 and a refrigerant solution heat exchanger 20; the outlet A of the three-way regulating valve 3 is connected with the condenser coolant solution inlet 1-4, and the outlet B of the three-way regulating valve 3 is connected with the generator coolant solution inlet 6-10, so that the coolant solution circulation is realized;

The generator dilute solution outlet 6-6 is connected with the absorber dilute solution inlet 13-2 through a pipeline by an absorbent solution heat exchanger 9 and a throttle valve 12; the concentrated solution outlet 13-4 of the absorber is divided into 2 parts after being pumped by an absorbent solution pump 11, the majority of the concentrated solution is heated by an absorbent solution heat exchanger 9, the minority of the concentrated solution is heated by a condensate heat exchanger (or a flue gas heat exchanger) 7, and then the concentrated solution is connected with the concentrated solution inlet 6-3 of the generator through a pipeline after being mixed, so that the circulation of the absorbent solution is completed;

the generator ammonia vapor outlet 6-1 is connected with the condenser ammonia vapor inlet 1-1, and the flooded evaporator ammonia vapor outlet 19-A-1 (or the surface-cooled evaporator ammonia vapor outlet 19-B-1) is connected with the absorber ammonia vapor inlet 13-1 to realize the refrigerant vapor flow;

when the low-level heat source is liquid or closed gas, the low-level heat source supply pipeline 18 is connected with the low-level heat source inlet 19-A-6 of the flooded evaporator 19A, and the low-level heat source return pipeline 17 is connected with the low-level heat source outlet 19-A-3 of the flooded evaporator 19A, so that a low-level heat source flow is realized;

when the low-level heat source is ambient air, the interface connection of the low-level heat source is not present;

the cooling water supply (or heat supply hot water return) 21 is connected with the condenser cooling water inlet 1-7, the condenser cooling water outlet 1-2 is connected with the absorber cooling water inlet 13-8, and then the absorber cooling water outlet 13-3 is connected with the cooling water return (or heat supply hot water supply) 10 to complete the cooling (heating) process;

When the driving source is steam, the driving steam 4 is connected with a driving steam inlet 6-8 of the generator 6 through a capacity regulating valve 5, a condensate outlet 6-5 of the generator 6 is connected with a condensate inlet of a condensate heat exchanger 7, and a condensate outlet of the condensate heat exchanger is connected with a condensate drainage pipeline 8; when the driving source is fuel gas, the driving fuel gas burner 5 is connected with the generator 6 to drive the flue gas inlet 6-8, the generator 6 smoke outlet 6-5 is connected with the flue gas inlet of the flue gas heat exchanger, and the flue gas outlet chimney 8 of the flue gas heat exchanger is connected to complete the driving flow.

The safety valve 2 is installed on the pipeline of the ammonia vapor outlet 6-1 of the generator.

The ammonia vapor refrigerant condensation section 1-8 of the condenser 1 is of a shell-and-tube structure, the heat transfer tube 1-8-1 of the ammonia vapor condensation section 1-8 is welded with the condensation section tube plate 1-8-2, ammonia vapor and a refrigerant solution (both downstream) are moved in the heat transfer tube 1-8-1, and cooling water is moved outside the heat transfer tube 1-8-1.

The primary ammonia vapor cooling section 1-11 of the condenser 1 is of a shell-and-tube structure, the heat transfer tube 1-11-1 of the primary ammonia vapor cooling section 1-11 is welded with the primary cooling section tube plate 1-11-2, ammonia vapor and condensation solution (both downstream) are moved in the heat transfer tube 1-11-1, and cooling water is moved outside the heat transfer tube 1-11-1.

The heat transfer tube 1-8-1 and the heat transfer tube 1-11-1 are made of 0Cr18Ni9 or high-quality carbon steel.

The rectifying section 6-2 of the generator 6 is composed of a plurality of herringbone baffle plates 24, the distance between every two adjacent baffle plates 24 is 5-10 mm, the height of each baffle plate is 200-400 mm, and 0Cr18Ni9 is selected as a material.

The solution regeneration section 6-4 of the generator 6 is of a shell-and-tube structure, the heat transfer tube 6-4-1 of the generator regeneration section 6-4 is welded with the regeneration section tube plate 6-4-2, ammonia steam and absorbent solution (counter current of the ammonia steam and the absorbent solution) are moved in the heat transfer tube 6-4-1, driving steam and condensed water (or flue gas) thereof are moved out of the heat transfer tube 6-4-1, and the heat transfer tube 6-4-1 is made of 00Cr22Ni5Mo3N or high-quality carbon steel.

The solution absorption section 13-7 of the absorber 13 is of a shell-and-tube structure, the heat transfer tube 13-7-1 of the absorption section 13-7 is welded with the tube plate 13-7-2 of the absorption section, ammonia steam and absorbent solution (counter current of the ammonia steam and the absorbent solution) are moved in the heat transfer tube 13-7-1, cooling water is moved outside the heat transfer tube 13-7-1, and the heat transfer tube 13-7-1 is made of 0Cr18Ni9 or high-quality carbon steel.

When the low-level heat source is liquid, the evaporation section 19-A-5 of the flooded evaporator 19A is of a tube shell structure, the heat transfer tube 19-A-5-1 of the evaporation section 19-A-5 of the flooded evaporator is welded with the evaporation section tube plate 19-A-5-2, ammonia steam and a refrigerant solution (both downstream) flow in the heat transfer tube 19-A-5-1, the low-level heat source in liquid state flows outside the heat transfer tube 19-A-5-1, and the heat transfer tube 19-A-5-1 is made of 0Cr18Ni9 or high-quality carbon steel.

When the low-level heat source is ambient air, the surface-cooled evaporator 19-B is of a finned tube structure, the inside of the finned tube 19-B-6 is provided with a refrigerant solution and boiling ammonia steam (both flow forward), the outside of the finned tube 19-B-6 is provided with air, and the finned tube 19-B-6 is made of 0Cr18Ni9 or high-quality carbon steel.

The heat exchange section 15-4 of the subcooler is of a shell-and-tube structure, a heat transfer tube 15-4-1 of the heat exchange section 15-4 of the subcooler is welded with a heat exchange section tube plate 15-4-2, the refrigerant solution of the evaporator 19 and boiling ammonia vapor (counter current of the two) flow in the heat transfer tube 15-4-1, the refrigerant solution of the condenser 1 flows in the shell pass of the heat transfer tube 15-4-1, and the heat transfer tube 15-4-1 is made of 0Cr18Ni9 or high-quality carbon steel and is connected to the tube plate in an expansion mode or welded on the tube plate.

The condenser liquid distributor 1-10, the generator liquid distributor 6-9 and the absorber liquid distributor 13-5 have the same structure and are composed of calandria, and drip holes are drilled on the calandria, so that liquid is conveniently discharged.

The absorber liquid distribution pipe 13-6 and the condenser liquid distribution pipe 1-9 have the same structure, the liquid distribution pipe is a hollow pipe, ammonia steam is arranged in the middle, solution is arranged at the inner side of the pipe wall and is arranged at the upper port of the heat transfer pipe, and the liquid distribution pipe is divided into three sections: the upper section is a liquid inlet section 1-9-a, and a notch 1-9-a-1 with the length of 30-50 mm and the width of 1-3 mm is formed along the periphery of the pipe at every 15-45 degrees; the middle is provided with a liquid homogenizing section 1-9-b, firstly, the solution flowing in through the notch 1-9-a-1 is uniformly distributed on the whole pipe wall, and the length is 40-100 mm; the lower end 1-9-c is an expansion joint section, which is connected in the end hole of the heat transfer tube 13-7-1 absorbed by the absorber or the condenser condensation section heat transfer tube 1-8-1 by expansion, and is made of 0Cr18Ni9 material.

A method for greatly reducing the condensation pressure of ammonia vapor in a condenser and simplifying the rectification process of a generator by using an ammonia water absorption heat pump comprises the following steps:

a refrigerant solution pump is arranged, the tail liquid of the refrigerant solution is conveyed to the condenser 1 to assist the condensation of ammonia vapor, and the condensation pressure is reduced; and a small amount of refrigerant solution tail liquid is sprayed to the generator 6, and ammonia steam at the outlet of the generator 6 is stripped, so that the rectification process is simplified.

The refrigerant solution tail liquid conveyed to the condenser 1 and the small amount of refrigerant solution tail liquid sprayed to the generator 6 are the refrigerant solution tail liquid evaporated by the evaporator 19, wherein the concentration is 60-90%.

A capacity adjusting method of ammonia water absorption heat pump load comprises the following steps:

the control target is the cooling water outlet temperature T4 of the absorber 13, and is realized by controlling the opening of the capacity control valve 5 (the burner when the driving source is a gas) on the driving steam pipe 4 by a PID system.

An ammonia water absorption heat pump condensation pressure P2 (or generation pressure) self-adaptive adjusting method comprises the following steps:

2) Setting a condenser pressure control value P0, and regulating the opening of the B side of the three-way regulating valve 3 in a PID mode by taking the condensing pressure P0 as a control target to regulate the amount of the refrigerant solution entering the generator 6;

3) When the pressure P2 of the condenser is higher than P0, the opening of the outlet B side of the three-way regulating valve 3 is regulated and reduced to reduce the refrigerant solution entering the generator 6, and when the pressure P2 of the condenser is lower than P0, the opening of the outlet B side of the three-way regulating valve 3 is regulated and controlled to be increased to increase the refrigerant solution entering the generator 6;

4) When the opening of the outlet B side of the three-way regulating valve 3 is regulated to the maximum, the pressure P2 of the condenser is still lower than P0 and is maintained for 20 seconds, the concentration of ammonia steam is calculated through an ammonia-water binary system state equation according to the condensation pressure P2 and the ammonia steam temperature T15, and the concentration of the ammonia steam is taken as a regulating target;

5) If the calculated ammonia vapor concentration is higher than 99.5%, regulating and controlling the opening degree of the outlet B side of the three-way regulating valve 3 to be reduced so as to reduce the refrigerant solution entering the generator 6, and if the ammonia vapor concentration is lower than 99.0%, regulating and controlling the opening degree of the outlet B side of the three-way regulating valve 3 to be increased so as to increase the refrigerant solution entering the generator 6;

6) When the condenser pressure P2 reaches P0, automatically switching to the regulation taking the condensing pressure P0 as a control target;

7) If the condenser pressure P2 is still higher than P0 after the refrigerant solution entering the generator 6 is reduced to 0 (the opening degree of the outlet of the side B of the three-way regulating valve is 0), immediately implementing capacity regulating opening limitation, rapidly limiting the opening degree of the capacity regulating valve 5 to be below 30%, if the condenser pressure P2 is still higher than P0 after maintaining for 180 seconds, completely closing the capacity regulating valve 5, and restarting the capacity regulating valve 5 after the condensing pressure is reduced to 0.8 times P0;

8) During the regulation, if a condensation pressure P2 greater than 1.2 times P0 occurs, the capacity control valve 5 is immediately closed.

The condenser pressure control value P0 is set according to the design operating pressure of the condenser 1, the purpose of which is to ensure that the condenser, generator, is operated below a safe pressure.

The self-adaptive regulating method for ammonia water thermodynamic cycle includes regulating refrigerant throttle valve, regulating solution throttle valve, regulating absorbent solution pump and regulating refrigerant solution pump.

setting an evaporator liquid level control value F10, detecting the evaporator liquid level F1, taking the F10 as a control target, and controlling the opening degree by adopting a PID mode to adjust the flow rate of the refrigerant solution entering the evaporator 19 so as to realize the thermodynamic cycle adjustment of ammonia water;

solution throttle valve adjustment, comprising the steps of:

setting a generator liquid level control value F20, detecting a generator liquid level F2, taking the F20 as a control target, controlling the opening degree of the generator liquid level F2 by adopting a PID mode, and adjusting the flow rate of the solution entering the absorber 13 to realize the thermodynamic cycle adjustment of ammonia water;

the absorbent solution pump adjustment comprises the following steps:

The concentration M1 of the ammonia water solution at the generator outlet is calculated through the condensing pressure P2 and the temperature T16 of the dilute solution at the generator outlet by an ammonia-water binary system state equation, the concentration M2 of the ammonia water solution at the absorber outlet is calculated through the evaporating pressure P3 and the temperature T18 of the concentrated solution at the absorber outlet by an ammonia-water binary system state equation, and the working frequency of an absorber solution pump is adjusted according to the M1 and the M2 in a variable frequency manner, so that the requirements are satisfied: when (1-M1)/(M2-M1) < 8 decreases in frequency, when (1-M1)/(M2-M1) > 15 increases in frequency; realizing the thermodynamic cycle adjustment of ammonia water;

the refrigerant solution pump adjustment comprises the following steps:

and under normal working conditions, the fixed frequency operation is realized.

When the ambient air is used as a low-level heat source, the evaporation section 19-B-6 of the evaporator 19 is of a finned tube structure, and air is taken away from the gaps between the fins outside the heat transfer tube. When the temperature of the heat transfer tube fins is lower than 0 ℃, water vapor in the air is sublimated on the fins to form frost, and when the thickness of the frost layer is to a certain degree, the heat exchange effect of the evaporator is greatly reduced, and at the moment, the evaporator needs to be defrosted.

The defrosting method of the ammonia water absorption heat pump evaporator comprises the following steps of:

the invention adopts an electric heating scheme, namely, an electric heating wire 19-B-9 is arranged in a liquid separation pipe 19-B-5;

Setting the reference end difference of the ambient temperature and the evaporating temperature as delta T (determining delta T value according to the heat transfer design of the evaporator), judging the actual end difference delta T of the ambient temperature T0 and the evaporating temperature T10, and starting a defrosting process when delta T is more than delta T, wherein the specific process is as follows:

1) Closing the capacity adjusting valve 5;

2) Stopping the absorbent solution pump 11, the refrigerant solution pump 14, and the evaporator fan 19-B-3;

3) Closing the frost control valve 19-B-8 and the refrigerant throttle valve 16;

4) Starting the electric heating wire 19-B-9;

5) Monitoring the pressure P3 of the evaporator and the temperature T10 of the liquid separation pipe, and stopping electric heating 19-B-9 after the pressure reaches 0.6MPa and 10 ℃;

6) After the electric heating is stopped, monitoring the fin temperature of the fin tube, if the temperature reaches 5 ℃, ending the melting of the frost;

7) Opening the frost control valve 19-B-8 and the refrigerant throttle valve 16, and starting the absorbent solution pump 11, the refrigerant solution pump 14 and the evaporator fan 19-B-3;

8) The capacity control valve 5 is opened and the heat pump is started.

The following will be described: the best embodiment of the invention is illustrated by taking the example of cooling water with an inlet of 45 ℃ and an outlet of 70 ℃, low-level heat source of ambient air with the temperature of minus 10 ℃ and a driving source of saturated steam with the pressure of 1.0MPa (corresponding to the saturated temperature of 180 ℃).

The condenser 1, the generator 6, the absorber 13, the evaporator 19, and the subcooler 15 are all installed vertically, and the perpendicularity deviation in the horizontal plane is not more than 1/1000.

The occurrence and condensation pressure was set to 1.875MPa and the evaporation pressure was set to 0.2MPa. The resistance of the ammonia vapor pipeline and the liquid baffle is not considered for the moment.

The evaporator 19 operates as follows:

ambient air at-10 ℃ is induced by a fan 19-B-3 and flows through a finned tube 19-B-6 of the evaporator 19, a refrigerant solution with a concentration of 85% (molar mass fraction, the same applies below) from the subcooler 15 in the evaporator 19 enters a liquid separating tube 19-B-5 and a finned tube 19-B-6 of the evaporator 19 through a refrigerant throttle valve 16 and a refrigerant solution inlet 19-B-5, and the evaporation temperature corresponding to 85% of the refrigerant solution is-14.8 ℃ under an evaporation pressure of 0.2MPa. The ammonia vapor is released by the boiling of the refrigerant vapor by the heating of the ambient air, enters the steam drum 19-B-7, and finally the concentration is reduced to 80% (the corresponding evaporation temperature is-12.9 ℃), and then enters the subcooler 15 through the refrigerant solution outlet 19-B-2 on the steam drum 19-B-7.

The subcooler 15 operates:

the refrigerant solution from the evaporator 19 is continuously boiled in the subcooler 15, and the heat of the 85% refrigerant solution from the condenser 1 is extracted to subcool it to about-8 ℃, then 80% refrigerant solution is sent from the refrigerant solution pump 14 to the refrigerant solution heat exchanger 20, and 85% refrigerant solution at about-8 ℃ is sent to the evaporator 19 through the refrigerant throttle valve 16.

The refrigerant solution heat exchanger 20 operates as follows:

in the refrigerant solution heat exchanger 20, 85% refrigerant solution having a temperature of about 54 ℃ from the condenser 1 exchanges heat with a refrigerant solution having a concentration of about 80% from the subcooler 15 at about-12.9 ℃, the temperature of 80% refrigerant solution is raised to about 50 ℃, the refrigerant solution enters the three-way regulating valve 3, the temperature of 85% refrigerant solution is lowered to about 5.3 ℃, and the refrigerant solution enters the subcooler 15 through the refrigerant throttle valve 16.

The condenser 1 works as follows:

in the condenser 1, ammonia vapor from the generator 6 is rectified by a refrigerant solution, the concentration is about 92-95%, the saturation temperature corresponding to 95% of the ammonia vapor is 107 ℃ under the pressure of 1-875 MPa, in order to improve the overall heat exchange effect of the condenser 1, the ammonia vapor firstly enters an ammonia vapor primary cooling section 1-11 for preliminary cooling, the ammonia vapor is cooled to about 64 ℃ (corresponding to the ammonia vapor concentration of about 99.6%), then enters a refrigerant condensing section 1-8, the tail liquid of the refrigerant solution from a three-way regulating valve 3 enters the condenser 1 through a refrigerant solution inlet 1-3 and a liquid distributor 1-10, and is mixed with condensate generated by the primary cooling section 1-11, enters an ammonia vapor refrigerant condensing section 1-8 through a liquid distributor 1-9, the ammonia vapor is absorbed by the refrigerant solution (corresponding to the saturation temperature of about 58 ℃) at about 80%, the final concentration reaches about 85% (corresponding to the saturation temperature of about 54 ℃) and enters a refrigerant solution storage cavity 1-5, then flows out of a refrigerant solution outlet 1-6 ℃ to the refrigerant solution outlet 1-11, enters the primary cooling section 1-11 through the heat exchanger, enters the primary cooling section 1-11 through the refrigerant pipe and enters the primary cooling section 1-11, and enters the primary cooling section 1-11 for heating through the refrigerant pipe 1-11, and enters the primary cooling section 1-11, and the ammonia vapor enters the primary cooling section 1-11 for heating section through the heat exchanger 1-11, and the primary cooling section.

Absorber 13 operation:

ammonia vapor (pressure 0.2MPa, concentration 99.99%) from the evaporator 19 enters the absorber 13, the 14% dilute solution from the generator 6 exchanges heat through the absorber solution heat exchanger 9, the temperature is about 72 ℃, the ammonia vapor is absorbed by the 14% dilute solution (corresponding to saturation temperature 81 ℃) in the solution absorption section 13-7 through the dilute solution inlet 13-2, the solution distributor 13-5 and the solution distribution pipe 13-6, the concentration is increased to 22% (corresponding to saturation temperature 64.4 ℃) and then enters the absorber solution heat exchanger 9 through the concentrated solution outlet 13-4 and the absorber solution pump 11.

The condenser 1 is supplied with cooling water at about 58 ℃ through the cooling water inlet 13-8 of the absorber 13 into the solution absorption section 13-7, and is supplied through the cooling water outlet 13-3 when the temperature is raised to 70 ℃.

The working process of the absorbent solution heat exchanger 9 comprises the following steps:

in the absorbent solution heat exchanger 9, the 14% solution from the generator 6 at a temperature of about 170 ℃ exchanges heat with the solution from the absorber 13 at a concentration of about 22%, the 22% solution is warmed to about 165 ℃ and enters the generator 6, and the 14% solution is cooled to 72 ℃ and enters the absorber 13.

The working process of the condensate heat exchanger 7 comprises the following steps:

in the condensate heat exchanger 7, the condensate water with the temperature of about 170 ℃ from the generator 6 exchanges heat with the solution with the concentration of about 22% from the absorber 13, the temperature of the solution with the concentration of 22% rises to about 165 ℃ and enters the generator 6, the condensate water temperature drops to 79 ℃ and is discharged out of the system through a condensate water drainage pipeline.

The generator 6 works as follows:

the solution with the temperature of about 165 ℃ and 22 percent enters the generator 6 through the concentrated solution inlet 6-3 and the liquid distributor 6-9. At the pressure of 1.875MPa, the corresponding saturated temperature of the 22% solution is about 150 ℃, the corresponding saturated ammonia vapor concentration is 76.5%, in the solution regeneration section 6-4, the driving steam of 1.0MPa heats the solution in the heat transfer pipe, the solution boils to release ammonia vapor, the concentration is reduced from 22% to 14% (the corresponding saturated temperature of 14% solution is about 170 ℃), the ammonia vapor released by the boiling of the solution regeneration section 6-4 flows upwards and is subjected to heat mass exchange with the concentrated solution, the concentration of the discharged liquid level is about 76.5%, the ammonia vapor enters the rectification section 6-2, in the rectification section 6-2, the 76.5% ammonia vapor and the 80% refrigerant solution tail liquid (at the pressure of 1.875MPa, the corresponding saturated ammonia vapor concentration is 99.6%) are subjected to heat mass exchange, and finally the ammonia vapor concentration leaving the rectification section 6-2 is increased to 92-95%, and the ammonia vapor is conveyed to the condenser 1 through the ammonia vapor outlet 6-1.

The working process of the three-way regulating valve 3 comprises the following steps:

the three-way regulating valve 3 has 2 outlets, namely an outlet A and an outlet B, wherein the outlet A is connected with the refrigerant solution inlet 1-3 of the condenser 1, and the outlet B is connected with the refrigerant solution inlet 6-10 of the generator 6. The three-way regulating valve 3 adjusts the opening degree according to the occurrence and condensation pressure.

If the generating and condensing pressure is higher than 1.875MPa, the opening of the outlet on the side B is properly closed, the amount of tail liquid of the refrigerant solution entering the generator 6 is reduced, as the refrigerant solution is reduced, the ammonia vapor rectification degree of the generator 6 is reduced, so that the concentration of ammonia vapor entering the condenser 1 is reduced, that is, the amount of ammonia vapor carrying working medium water from the generator and absorber side into the condenser and evaporator side is increased, the refrigerant solution carrying working medium water from the condenser and evaporator side is reduced to supplement the generator and absorber side, and a large amount of working medium water is collected on the condenser and evaporator side at the moment, so that the ammonia water thermodynamic cycle is adjusted: the concentration of the refrigerant solution at the side of the condenser and the evaporator is reduced, and the corresponding saturation pressure is reduced at the same saturation temperature after the concentration of the refrigerant solution is reduced, so that the condensation pressure of the condenser is reduced along with the reduction of the concentration of the refrigerant solution, and the adjustment of the condensation pressure and the generation pressure is realized.

Similarly, if the occurrence and condensation pressure is lower than 1.875MPa, the opening of the outlet B is properly increased, the amount of the refrigerant solution entering the generator 6 is increased, and the ammonia vapor rectification degree of the generator 6 is improved.

The flow rate of the generator refrigerant solution is regulated to regulate the generation and condensation pressure, certain hysteresis exists, in order to prevent the generator 6 and the condenser 1 from running beyond the safe pressure, when the opening of the outlet B is reduced to 0 and the condensation pressure is higher than 1.875MPa, or when the condensation pressure is 1.2 times higher than 1.875MPa in the regulation process, the capacity regulating valve is opened and limited, namely the capacity regulating valve is forcedly closed, the steam inlet of the generator is reduced, and the generation pressure is reduced.

When the concentration of ammonia vapor entering the condenser exceeds 99%, the rectification degree of the generator is very high, and if the occurrence and condensation pressure is lower than 1.875MPa, the reason is no longer caused by the lower concentration of the condenser refrigerant solution, and therefore the adjustment by increasing the flow rate of the generator refrigerant solution is not needed, and therefore, the opening of the B side of the three-way regulating valve is no longer adjusted according to the occurrence and condensation pressure: and calculating the concentration of ammonia vapor according to the condensation pressure P2 and the ammonia vapor temperature T15, and regulating the opening of the three-way regulating valve in a PID mode by taking the ammonia vapor concentration of 99.5% as a control target to maintain the ammonia vapor concentration to be near 99.5%.

The refrigerant throttle valve 16 operates:

when the concentration of the refrigerant solution changes due to the change of the cooling water inlet temperature or the adjustment of the condensing pressure, the circulation of the refrigerant solution on the condensing and evaporating sides is regulated by the refrigerant throttle valve 16, and the opening degree of the refrigerant throttle valve 16 is controlled according to the liquid level of the evaporator 19.

When the cooling water inlet temperature of the condenser 1 is increased or the condensing pressure is higher than 1.875MPa, the three-way regulating valve 3 can reduce the amount of the generator refrigerant solution, the concentration of the refrigerant solution in the condenser is reduced due to the reduction of the concentration of the ammonia vapor entering the condenser, after the concentration of the refrigerant solution in the condenser 1 is reduced, the evaporator 19 can store the refrigerant solution under the condition that the low-level heat source temperature is unchanged, at this time, the opening degree of the refrigerant solution throttle valve 16 is regulated according to the evaporator liquid level, the amount of the refrigerant solution entering the evaporator 19 is reduced, meanwhile, the refrigerant solution storage amount of the condenser 1 is increased by the refrigerant solution storage cavities 1-5, the refrigerant solution with higher concentration is stored due to the increase of the refrigerant solution storage cavities 1-5, and after corresponding regulation, the average concentration of the whole ammonia water circulating ammonia solution including the generator and the absorber side is reduced until the temperature corresponds to the cooling water inlet temperature of the condenser or the condensing pressure maintaining 1.875 MPa.

When the cooling water inlet temperature of the condenser 1 is reduced or the condensing pressure is lower than 1.875MPa, the three-way regulating valve 3 increases the amount of the generator refrigerant solution, the concentration of the refrigerant solution in the condenser 1 is increased due to the increase of the concentration of the ammonia vapor entering the condenser, after the concentration of the refrigerant solution in the condenser 1 is increased, the refrigerant solution in the evaporator 19 is reduced under the condition that the temperature of a low-level heat source is unchanged, at the moment, the opening degree of the refrigerant solution throttling valve 16 is regulated according to the liquid level of the evaporator 19, the amount of the refrigerant solution entering the evaporator 19 is increased, meanwhile, the storage amount of the refrigerant solution in the condenser is reduced due to the fact that the storage cavity of the refrigerant solution is reduced by the refrigerant solution with higher concentration, and after corresponding regulation, the average concentration of the whole ammonia water circulating ammonia solution including the generation side and the absorption side is increased until the temperature corresponds to the cooling water inlet temperature of the condenser or the condensing pressure of maintaining 1.875 MPa.

Solution throttle valve 12, absorbent solution pump 11 working process:

the purpose of the solution throttle valve 12 and the absorbent solution pump 11 is to keep the liquid level balance of the generator 6 and the absorber 13, thereby realizing the adjustment of the whole ammonia thermodynamic cycle.

The solution throttle valve 12 controls the opening degree according to the pressure difference value of the generator 6 and the absorber 13; the absorbent solution pump 11 adjusts the operation frequency according to the liquid level frequency conversion of the generator 6, and when the pressure difference is increased, the opening of the solution throttle valve 12 is reduced in order to prevent excessive solution from entering the absorber 13; at the same time, in order to prevent dry combustion caused by the lower liquid level of the generator 6, the solution pump 11 can increase the operating frequency and increase the flow rate of the concentrated solution entering the generator 6.

Defrosting process of the evaporator:

monitoring the ambient temperature T5 to be less than 0 ℃, for example, the difference between the temperature T5 and the ammonia vapor temperature T9 at the outlet of the evaporator is more than 10 ℃ (adjustable), which indicates that the evaporator is frosted seriously. At this time:

1) Closing the capacity adjusting valve 5;

2) Stopping the absorbent solution pump 11, the refrigerant solution pump 14, and the fan 19-B-3 of the evaporator 19B;

4) Starting the electric heating wire 19-B-9;

5) Monitoring the pressure P3 of the evaporator and the temperature T10 of the liquid separation pipe, and stopping electric heating after the pressure reaches 0.6MPa and 10 ℃;

6) After the electric heating 19-B-9 is stopped, monitoring the temperature T10 of the liquid distribution pipe, if the temperature reduction amplitude is less than 1 ℃ within 30 seconds (adjustable), and ending the melting frost;

7) Opening the frost control valve 19-B-8 and the refrigerant throttle valve 16, and starting the absorbent solution pump 11, the refrigerant solution pump 14 and the fan 19-B-3 of the evaporator 19;

8) The capacity control valve 5 is opened and the heat pump is started.

Through the embodiment, the ammonia water absorption heat pump and the control method thereof can realize the ammonia water heat pump cycle with the energy efficiency ratio (the ratio of the heat taken by the cooling water to the consumed heat of the generator) of about 1.35 by using the steam drive of 1.0MPa under the conditions that the cooling water enters and exits at 50-70 ℃ and the ambient air is at-10 ℃. Under the pressure of 1.875MPa, the outlet temperature of the cooling water reaches 70 ℃, which is far lower than the saturation pressure of 3.8MPa corresponding to the 70 ℃ of the pure ammonia working medium, thus realizing the low-pressure operation of the condenser and the generator.

The embodiment is only a part of the application range of the invention, and the invention can complete heat pump circulation and realize heating temperature above 60 ℃ for low-level heat sources or waste heat sources such as ambient air with temperature more than or equal to-20 ℃, chemical raw material gas, circulating cooling water and the like.

The present invention is not limited to the above embodiments, and any person who is in the light of the present invention should be informed that the technical solution that is the same as or similar to the present invention falls within the protection scope of the present invention.

The technology, shape, and construction parts of the present invention, which are not described in detail, are known in the art.

Claims

1. The ammonia water absorption heat pump is characterized by comprising a condenser, a generator, an evaporator, an absorber, a subcooler, a refrigerant solution heat exchanger, an absorbent solution heat exchanger, a refrigerant solution pump, an absorbent solution pump, a three-way regulating valve, a capacity regulating valve, a refrigerant throttle valve, a solution throttle valve, a condensate heat exchanger and a safety valve;

the condenser is constructed as follows:

the condenser consists of a condenser ammonia vapor inlet, a condenser cooling water outlet, a condenser refrigerant solution inlet, a cooling water connecting pipe, a condenser refrigerant solution storage cavity, a condenser refrigerant solution outlet, a condenser cooling water inlet, an ammonia vapor condensing section, a condenser refrigerant solution liquid distribution pipe, a condenser refrigerant solution liquid distributor and an ammonia vapor primary cooling section; the ammonia vapor condensing section is of a shell-and-tube structure, ammonia vapor and a refrigerant solution are moved in a heat transfer tube of the condensing section, cooling water is moved on the shell side of the heat transfer tube of the condensing section, and the heat transfer tube of the condensing section is made of 0Cr18Ni9 or high-quality carbon steel material and is welded on a tube plate; the primary cooling section of ammonia vapor is of a shell-and-tube structure, ammonia vapor and condensate are moved in the primary cooling section heat transfer tube, cooling water is moved in the shell of the primary cooling section heat transfer tube, and the primary cooling section heat transfer tube is made of 0Cr18Ni9 or high-quality carbon steel material and is welded on a tube plate;

The generator is constructed as follows:

the generator consists of a generator ammonia steam outlet, a rectifying section, a generator concentrated solution inlet, a solution regenerating section, a condensate outlet, a generator dilute solution storage cavity, a driving steam inlet, a generator liquid distributor, a generator refrigerant solution inlet and a generator refrigerant solution sprayer; the rectifying section consists of herringbone baffle plates, the space between the baffle plates is 5-10 mm, the height is 200-400 mm, and the material is 0Cr18Ni9; the solution regeneration section is of a tube shell structure, solution and ammonia vapor are moved in a heat transfer tube of the regeneration section, vapor and condensed water thereof are moved on the shell side of the heat transfer tube of the regeneration section, and the heat transfer tube of the regeneration section is made of 00Cr22Ni5Mo3N or high-quality carbon steel materials and is welded on a tube plate;

the absorber is constructed as follows:

the absorber consists of an absorber dilute solution inlet, an absorber cooling water outlet, an absorber concentrated solution outlet, an absorber ammonia steam inlet, an absorber concentrated solution storage cavity, an absorber cooling water inlet, a solution absorption section, an absorber solution distributor and an absorber solution distribution pipe; the solution absorption section of the absorber is of a shell-and-tube structure, solution and ammonia vapor are removed from the heat transfer tube of the absorption section, cooling water is removed from the shell side of the heat transfer tube of the absorption section, and the heat transfer tube of the absorption section is made of 0Cr18Ni9 or high-quality carbon steel material and is welded on a tube plate;

The evaporator is constructed as follows:

when the low-level heat source is liquid or closed gas, the evaporator is a flooded evaporator, and consists of an ammonia vapor outlet of the flooded evaporator, a refrigerant solution outlet of the flooded evaporator, a low-level heat source outlet, a refrigerant solution inlet of the flooded evaporator, an evaporation section and a low-level heat source inlet; the evaporator evaporation section is of a shell-and-tube structure, a refrigerant solution and ammonia vapor are moved in a heat transfer tube of the evaporation section, a low-level heat source is moved on the shell side of the heat transfer tube of the evaporation section, and the heat transfer tube of the evaporation section is made of 0Cr18Ni9 or high-quality carbon steel material and is welded on a tube plate; when the low-level heat source is ambient air, the evaporator is of a surface cooling structure and consists of a surface cooling evaporator ammonia steam outlet, a surface cooling evaporator refrigerant solution outlet, a fan, a surface cooling evaporator refrigerant solution inlet, a liquid separation pipe, a fin pipe, a steam drum, a frost melting control valve and an electric heating wire; the inside of the finned tube is provided with a refrigerant solution and boiling ammonia steam, the outside of the finned tube is provided with air, and the finned tube is made of 0Cr18Ni9 or high-quality carbon steel;

the interfaces of the components are connected and communicated as follows:

the condenser refrigerant solution outlet is connected with the refrigerant solution inlet of the flooded evaporator through a pipeline, a refrigerant solution heat exchanger, a subcooler and a refrigerant throttle valve; the refrigerant solution outlet of the flooded evaporator is connected with the inlet of the three-way regulating valve through a pipeline by a cooler, a refrigerant solution pump and a refrigerant solution heat exchanger; two outlets of the three-way regulating valve are divided into an outlet A and an outlet B, the side of the outlet A is connected with a condenser refrigerant solution inlet, and the side of the outlet B of the three-way regulating valve is connected with a generator refrigerant solution inlet;

The generator dilute solution outlet is connected with the absorber dilute solution inlet through a pipeline by an absorbent solution heat exchanger and a solution throttle valve; the concentrated solution outlet of the absorber is divided into 2 parts after being pumped by the absorbent solution pump, the majority of the concentrated solution outlet is heated by the absorbent solution heat exchanger, the minority of the concentrated solution outlet is heated by the condensate heat exchanger, and the concentrated solution outlet is connected with the concentrated solution inlet of the generator through a pipeline after being mixed;

the ammonia vapor outlet of the liquid filling type evaporator is connected with the ammonia vapor inlet of the absorber;

when the low-level heat source is liquid or closed gas, the low-level heat source supply pipeline is connected with the low-level heat source inlet of the flooded evaporator, and the low-level heat source return pipeline is connected with the low-level heat source outlet of the flooded evaporator; when the low-level heat source is ambient air, the interface connection of the low-level heat source is not present;

the cooling water supply is connected with a condenser cooling water inlet, a condenser cooling water outlet is connected with an absorber cooling water inlet, and then the absorber cooling water outlet is connected with cooling water backwater;

when the driving source is steam, the driving steam is connected with a driving steam inlet of the generator through a capacity regulating valve, a condensed water outlet of the generator is connected with a condensed water inlet of the condensed water heat exchanger, and a condensed water outlet of the condensed water heat exchanger is connected with a condensed water drainage pipeline; when the driving source is fuel gas, the driving fuel gas burner is connected with a generator driving flue gas inlet, a generator flue gas outlet is connected with a flue gas inlet of a flue gas heat exchanger, and a flue gas outlet of the flue gas heat exchanger is connected with a chimney;

The safety valve is installed on the ammonia vapor line from the generator to the condenser.

2. An aqueous ammonia absorption heat pump according to claim 1, wherein: the liquid distribution pipe of the condenser and the liquid distribution pipe of the absorber are respectively provided with a liquid distribution pipe, and the liquid distribution pipe is divided into three sections: the upper end is a liquid inlet section, and a notch with the length of 30-50 mm and the width of 1-3 mm is formed along the periphery of the pipe at each 15-45 degrees; the middle part is a liquid homogenizing section with the length of 40-100 mm; the lower end is an expansion joint section which is connected with a heat transfer pipe of an absorber absorption section or a condenser condensation section.

3. A method for reducing condensation pressure and simplifying rectification process by using the ammonia absorption heat pump as defined in any one of claims 1-2, which is characterized in that: the method comprises the following steps:

1) Setting a refrigerant solution pump, and pumping the tail liquid of the refrigerant solution evaporated by the evaporator, wherein the concentration is 60-90%;

3) And a small amount of refrigerant solution tail liquid is sprayed to the generator through refrigerant solution circulation, and ammonia steam at the outlet of the generator is stripped, so that the rectification process is simplified.

4. A method for regulating the capacity of an ammonia absorption heat pump load according to any one of claims 1 to 2, characterized in that: the method comprises the following steps:

And controlling the opening of the capacity regulating valve by taking the outlet temperature of the cooling water of the absorber as a control target and adopting a PID mode.

5. A method for adaptively adjusting the condensing pressure of an ammonia absorption heat pump according to any one of claims 1 to 2, characterized by: the method comprises the following steps:

2) Setting a condenser pressure control value P0, and regulating the opening of the outlet B side of the three-way regulating valve in a PID mode by taking the condensing pressure P0 as a control target to regulate the tail liquid amount of the refrigerant solution entering the generator;

3) When the pressure P2 of the condenser is higher than P0, the opening of the outlet B side of the three-way regulating valve is regulated and reduced to reduce the tail liquid of the refrigerant solution entering the generator, and when the pressure P2 of the condenser is lower than P0, the opening of the outlet B side of the three-way regulating valve is regulated and controlled to be larger to increase the tail liquid of the refrigerant solution entering the generator;

4) When the opening of the outlet B side of the regulating three-way regulating valve is regulated to the maximum, the pressure P2 of the condenser is still lower than P0 and is maintained for 20 seconds, the concentration M3 of ammonia steam is calculated according to the condensing pressure P2 and the ammonia steam temperature T through an ammonia-water binary system state equation, and the opening of the outlet B side of the regulating three-way regulating valve is regulated and controlled by taking the ammonia steam concentration M3 as a target;

5) If the calculated ammonia vapor concentration M3 is higher than 99.5%, regulating and controlling the opening of the outlet B side of the three-way regulating valve to be reduced so as to reduce the tail liquid of the refrigerant solution entering the generator, and if the ammonia vapor concentration M3 is lower than 99.0%, regulating and controlling the opening of the outlet B side of the three-way regulating valve to be increased so as to increase the tail liquid of the refrigerant solution entering the generator;

7) If the tail liquid of the refrigerant solution entering the generator is reduced to 0, the pressure P2 of the condenser is still higher than P0, the opening of the capacity regulating valve is rapidly limited to be below 30%, if the pressure P2 of the condenser is still higher than P0 after 180 seconds, the capacity regulating valve is completely closed, and the capacity regulating valve is restarted after the condensing pressure is reduced to 0.8 times of P0;

8) During the regulation, if a condensation pressure P2 greater than 1.2 times P0 occurs, the capacity control valve is immediately closed.

6. An ammonia absorption heat pump thermodynamic cycle self-adaptive adjustment method according to any one of claims 1-2, comprising the steps of:

1) Setting an evaporator liquid level control value F10, detecting the evaporator liquid level F1, taking the F10 as a target value, and controlling the opening of a refrigerant throttle valve in a PID mode to adjust the flow rate of the refrigerant solution entering the evaporator;

2) Setting a generator liquid level control value F20, detecting the generator liquid level F2, taking the F20 as a target value, controlling the opening of a solution throttle valve in a PID mode, and adjusting the flow of the solution entering the absorber;

3) Detecting condensing pressure P2 and generator outlet dilute solution temperature T16, calculating generator outlet ammonia water solution concentration M1 through an ammonia-water binary system state equation, detecting evaporating pressure P3 and absorber outlet concentrated solution temperature T18, calculating absorber outlet ammonia water solution concentration M2 through an ammonia-water binary system state equation, and adjusting the working frequency of an absorber solution pump according to M1 and M2 in a variable frequency manner, wherein the working frequency of the absorber solution pump is satisfied: when (1-M1)/(M2-M1) < 8 decreases in frequency, when (1-M1)/(M2-M1) > 15 increases in frequency;

4) The coolant solution pump operates at a fixed frequency.