CN118274483A - Efficient hot water type lithium bromide absorption unit - Google Patents

Abstract

The invention provides a high-efficiency hot water type lithium bromide absorption unit, which comprises an evaporator, an absorber, a generator and a condenser, wherein the evaporator, the absorber and the generator are subjected to two-stage heat exchange, the condenser is subjected to single-stage heat exchange, the unit mainly comprises two independent solution circulation loops and a refrigerant pipeline, and the first-stage generator, a first-stage solution heat exchanger, a first-stage solution pump and the first-stage absorber are connected through pipelines to form a first-stage solution circulation loop; the second-stage generator, the second-stage solution heat exchanger, the second-stage solution pump and the second-stage absorber are connected through pipelines to form a second-stage solution circulation loop. The unit reduces or replaces the consumption of high-grade heat energy by recycling the middle-low temperature residual water of the factory, thereby improving the comprehensive utilization efficiency of energy; the variable working condition adjustment can be realized, and the adaptability to the temperature change of the waste heat water is good; meanwhile, the power consumption of the unit can be reduced, and a better heat exchange effect is achieved.

Description

Efficient hot water type lithium bromide absorption unit

Technical Field

The invention relates to the technical field of waste heat heating and refrigeration, in particular to a high-efficiency hot water type lithium bromide absorption unit.

Background

The industrial production process often generates a large amount of medium-low temperature waste heat, the waste heat cannot be continuously utilized by the process because of low temperature, and the heat is usually discharged into the environment in a water-cooling or air-cooling mode, so that the waste of heat energy is caused. Therefore, the reinforcement of waste heat recovery and utilization is a main way of saving energy, and relates to various high-efficiency energy-saving devices, waste heat recovery and utilization devices and energy-saving technology application. Various lithium bromide absorption heat pumps and water chilling units based on lithium bromide absorption technology are equipment which is driven by heat energy to operate, lithium bromide solution is used as an absorbent, water is used as a refrigerant, and the heat energy of waste heat water is recycled to realize heating and refrigerating.

According to the difference of driving heat sources, the hot water type, steam type and direct combustion type absorption units are generally classified. Under most working conditions, the medium-low temperature waste heat exists in the forms of condensed water, heat medium water and cooling medium. Wherein, the hot water with the temperature of more than or equal to 90 ℃ can be used as a driving heat source of a hot water type absorption heat pump and a cold water machine set generator, and the hot water with the temperature of between 25 and 50 ℃ can be used as a low-temperature heat source of a hot water type absorption heat pump evaporator.

The existing hot water type absorption heat pump and water chiller consists of an evaporator, an absorber, a generator, a condenser, a solution heat exchanger, a solution pump, a refrigerant pump, a control system, and pipelines and valves for connecting the components. The lithium bromide unit is a device for heating and refrigerating water by utilizing the fact that the evaporation temperature of water is low under negative pressure and the temperature of water vapor absorbed by lithium bromide-water solution is increased to release heat to the outside.

In practical applications, the existing lithium bromide absorption unit can only supply hot water or cold water under a single working condition, and because the principles of refrigeration and heating are different, if the lithium bromide absorption unit is required to meet the functions of a heat pump and cold water, corresponding consideration and setting are required to be performed during design, and a small amount of one-machine dual-purpose heat pump type lithium bromide cold water unit can only provide low-temperature hot water under the condition of providing cold water. And when the waste water is used as a driving heat source or a heating low-temperature heat source, the temperature of the waste water fluctuates along with the continuous change of working conditions, so the temperature of the waste water can be sometimes lower. When the temperature of the waste heat water is lower as the driving hot water, the heating amplitude of the heating water is limited, and the temperature of the heating water outlet is possibly lower and cannot meet the requirement of the water supply temperature; similarly, the cooling range of the cold water is limited, so that the temperature of the cold water outlet is higher, and the water supply temperature requirement cannot be met. Therefore, high-efficiency lithium bromide absorption units are not available at present, and variable-working-condition application equipment for hot water and cold water supply is considered.

Disclosure of Invention

In view of the above, the present invention aims to provide a high-efficiency hot water absorption unit, so as to solve the problems of low heat exchange efficiency and variable working condition application of the lithium bromide absorption unit in the prior art.

In order to achieve the above purpose, the technical scheme of the invention is realized as follows:

The efficient hot water type lithium bromide absorption unit is characterized by comprising an evaporator, an absorber, a generator and a condenser, wherein the evaporator, the absorber and the generator are subjected to two-stage heat exchange, the condenser is subjected to single-stage heat exchange, the unit mainly comprises two independent solution circulation loops and a refrigerant pipeline, and the first-stage generator, the first-stage solution heat exchanger, the first-stage solution pump and the first-stage absorber are connected through pipelines to form a first-stage solution circulation loop; the second-stage generator, the second-stage solution heat exchanger, the second-stage solution pump and the second-stage absorber are connected through pipelines to form a second-stage solution circulation loop. The heat loads of the two-stage evaporator, the two-stage absorber and the two-stage generator are more balanced by adjusting the working concentrations of the lithium bromide concentrated solution and the lithium bromide diluted solution of the two solution circulation loops, so that a better heat exchange effect is achieved.

Further, the condenser is connected with the first-stage evaporator through a pipeline, and the second-stage evaporator is respectively connected with the first-stage evaporator and the refrigerant pump through pipelines to form a refrigerant pipeline.

Preferably, the refrigerant pump is connected in parallel with the first stage evaporator and the second stage evaporator by a spray device. The parallel connection mode only needs to install 1 refrigerant pump, so that the operating parts of the unit are reduced, the power consumption of the unit is reduced, and the running reliability of the unit is improved.

Further, the first-stage absorber and the first-stage evaporator are communicated with each other to form a first-stage refrigerant steam flow channel; the second-stage absorber and the second-stage evaporator are communicated with each other to form a second-stage refrigerant steam flow channel; the first-stage generator and the condenser are communicated with each other to form a third-stage refrigerant steam flow channel; the second-stage generator and the condenser are communicated with each other to form a fourth-stage refrigerant steam flow channel.

Further, the solutions in the two solution circulation loops are kept independent of each other and have different concentrations. The device can be better adapted to the temperature conditions of the waterway sides of the absorber and the generator in the respective loops and the working pressure of the vacuum sides of the absorber and the generator, and achieves better heat exchange effect.

Further, the refrigerant vapor flow channels of each stage are all kept in a vacuum state, the working pressures in the refrigerant vapor flow channels of the first stage are equal, the working pressures in the refrigerant vapor flow channels of the second stage are equal, the working pressures in the refrigerant vapor flow channels of the third stage are equal, and the working pressures in the refrigerant vapor flow channels of the fourth stage are equal.

Further, the first-stage generator, the second-stage generator, the first-stage absorber, the second-stage absorber, the first-stage evaporator, the second-stage evaporator and the condenser are respectively a heat exchange cavity, a plurality of rows of heat exchange tube bundles are arranged in each heat exchange cavity, and each heat exchange tube bundle consists of a plurality of horizontally placed heat exchange tubes.

Furthermore, the inside of the heat exchange tube is a waterway side, and the outside of the heat exchange tube is a vacuum side.

Furthermore, spray devices are arranged above the heat exchange pipes of the first-stage generator, the second-stage generator, the first-stage absorber, the second-stage absorber, the first-stage evaporator and the second-stage evaporator.

Furthermore, the driving heat source or the low-temperature heat source of the unit is waste heat water, and meanwhile, the variable working condition adjustment can be realized.

Compared with the prior art, the efficient hot water type lithium bromide absorption unit has the following advantages:

The invention reduces or replaces the consumption of high-grade heat energy by recycling the middle-low temperature residual water of the factory, thereby improving the comprehensive utilization efficiency of energy; the evaporator, the absorber and the generator all adopt two-stage heat exchange, the condenser adopts single-stage heat exchange, so that irreversible heat loss in the heat transfer process can be reduced, the performance of the unit is improved, the structural arrangement of the unit is facilitated, and the manufacturing cost is reduced; meanwhile, two independent solution circulation loops are formed, lithium bromide solutions of the two circulation loops are not communicated with each other and have different concentrations, so that the lithium bromide solution heat exchange device can better adapt to temperature conditions of water paths of an absorber and a generator and working pressures of vacuum sides of the absorber and the generator in the respective loops, and heat loads of the two-stage evaporator, the two-stage absorber and the two-stage generator are more balanced by adjusting working concentrations of concentrated lithium bromide solution and dilute lithium bromide solution of the two solution circulation loops, the total heat exchange area of a unit is reduced, and a better heat exchange effect is achieved; the variable working condition adjustment can be realized, and the variable working condition adjustment device can be used for both the waste heat water heating working condition and the waste heat water refrigerating working condition, and can be applied to both hot water and cold water supply.

Drawings

FIG. 1 is a schematic diagram of embodiment 1 of the present invention;

FIG. 2 is a schematic diagram of embodiment 2 of the present invention;

FIG. 3 is a schematic diagram of embodiment 3 of the present invention;

FIG. 4 is a schematic view of embodiment 4 of the present invention

Reference numerals illustrate:

A solution pump 1, a first-stage solution pump 11, and a second-stage solution pump 12; a refrigerant pump 2; a generator 3, a first stage generator 31, a second stage generator 32; a condenser 4; a first-stage absorber 51, a second-stage absorber 52; a first-stage evaporator 61, a second-stage evaporator 62; a solution heat exchanger 7, a first-stage solution heat exchanger 71, a second-stage solution heat exchanger 72; a first heat exchange tube bundle 81, a second heat exchange tube bundle 82; a third heat exchange tube bundle 9; a fourth heat exchange tube bundle 101, a fifth heat exchange tube bundle 102; a sixth heat exchanger tube bundle 111, a seventh heat exchanger tube bundle 112.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.

Embodiment one:

As shown in figure 1, the unit adopts two-stage heat exchange for an evaporator and an absorber, adopts single-stage heat exchange for a generator and a condenser, adopts vacuum equipment with extremely high air tightness (can form a low-pressure environment to enable cryogen water to evaporate at a low temperature), and is provided with an air extractor in a vacuum state unit for keeping the inside of the unit, wherein the air extractor can be a mechanical vacuum pump air exhausting system or an automatic air exhausting system. The air extractor is not shown in the drawings because it does not belong to the scope of the present patent application.

The unit consists of a solution circulation loop and a refrigerant pipeline, the solution heat exchanger 7 is respectively connected with the generator 3 and the first-stage absorber 51 through the pipeline to form a concentrated solution loop, and the second-stage absorber 52 is respectively connected with the first-stage absorber 51, the solution pump 1 and the solution heat exchanger 7 to form a dilute solution loop; wherein the dilute solution loop and the concentrated solution loop together form a solution circulation loop; the condenser 4 is connected with the first-stage evaporator 61, the second-stage evaporator 62 is respectively connected with the first-stage evaporator 61 and the refrigerant pump 2 to form a refrigerant pipeline, and the condenser 4 is connected with the first-stage evaporator 61 in a unidirectional way to form a refrigerant water return pipeline; the refrigerant pump 2 is connected in parallel with the first stage evaporator 61 and the second stage evaporator 62 through a spray device; the generator 3 and the condenser 4 are communicated with each other to form a refrigerant steam flow channel; the first-stage absorber 51 and the first-stage evaporator 61 communicate with each other to constitute a first-stage refrigerant vapor flow passage; the second-stage absorber 52 and the second-stage evaporator 62 communicate with each other to constitute a second-stage refrigerant vapor flow passage. The refrigerant vapor flow channels at all levels are kept in a vacuum state, the working pressures in the refrigerant vapor flow channels at the first level are equal, the working pressures in the refrigerant vapor flow channels at the second level are equal, the working pressures in the refrigerant vapor flow channels at the third level are equal, and the working pressures in the refrigerant vapor flow channels at the fourth level are equal.

The generator 3, the first-stage absorber 51, the second-stage absorber 52, the first-stage evaporator 61, the second-stage evaporator 62 and the condenser 4 are each a heat exchange chamber, and a plurality of rows of heat exchange tube bundles are installed in each heat exchange chamber, wherein each heat exchange tube bundle is composed of a plurality of horizontally placed heat exchange tubes. Wherein the inside of the heat exchange tube is a waterway side, and the outside of the heat exchange tube is a vacuum side. Spray devices are provided above the heat exchange tubes of the generator 3, the first-stage absorber 51, the second-stage absorber 52, the first-stage evaporator 61 and the second-stage evaporator 62.

The waterway side of the heat exchange tube of the generator 3 is connected with a high-temperature heat source water inlet and a high-temperature heat source water outlet; the waterway sides of the heat exchange tubes of the second-stage evaporator 62 and the first-stage evaporator 61 are respectively connected with a low-temperature heat source water inlet and a low-temperature heat source water outlet through pipelines; the water path side of the heat exchange pipe of the second-stage absorber 52 is connected with the backwater inlet of heating water and the water path side of the heat exchange pipe of the first-stage absorber 51 respectively through pipelines, and the water path side of the heat exchange pipe of the condenser 4 is connected with the water path side of the heat exchange pipe of the first-stage absorber 51 and the water supply outlet of heating water respectively through pipelines.

Driving hot water to enter a heat exchange tube of the generator 3 as a high-temperature heat source, heating and concentrating lithium bromide dilute solution on the outer vacuum side of the tube by the driving hot water in the generator 3, generating refrigerant steam in the process, changing the lithium bromide dilute solution into concentrated solution, flowing out, discharging the concentrated solution, cooling by heat release of a solution heat exchanger 7, entering a first-stage absorber 51, spraying the concentrated solution to the outer vacuum side of the heat exchange tube bundle of the first-stage absorber 51 from the top, absorbing the refrigerant steam from a first-stage evaporator 61, and discharging absorption heat; the concentrated solution is diluted and then flows out through the solution flow path to the second-stage absorber 52, absorbs the refrigerant vapor from the second-stage evaporator 62, and emits absorption heat, and the lithium bromide solution is further diluted to become a diluted solution. The concentrated lithium bromide solution is gradually absorbed by the two absorbers from the refrigerant steam in the evaporator, the concentrated lithium bromide solution is gradually diluted, the absorbed heat is released twice, the heat source of the unit is increased, and meanwhile, the heat loss of the unit in the working state is reduced. Under the supercharging drive of the solution pump 1, the solution is subjected to heat exchange with the high-temperature lithium bromide concentrated solution through the solution exchanger 7, and enters the generator 3 after the temperature is raised, and then the solution is heated and concentrated by the driving hot water, so that a solution circulation loop is completed.

The refrigerant vapor generated in the generator 3 enters the condenser 4 through the refrigerant vapor flow channel, condenses on the external vacuum side of the third heat exchange tube bundle 9, gives off condensation heat, turns into refrigerant water, sprays into the refrigerant water from the top of the first-stage evaporator 61 through the refrigerant water return channel, one part of the refrigerant water absorbs and evaporates heat in the residual heat water outside the heat exchange tubes of the first-stage evaporator 61, the generated refrigerant vapor enters the first-stage absorber 51 through the first-stage refrigerant vapor flow channel and is absorbed by the lithium bromide concentrated solution, the other part of the non-evaporated refrigerant water flows out of the first-stage evaporator 61, enters the second-stage evaporator 62 through the refrigerant water flow channel and continuously absorbs heat in the residual heat water and is absorbed by the solution, and the two-stage evaporators can provide the refrigerant vapor to the corresponding absorbers step by step, so that the refrigerant vapor yield is obviously higher than that of the single-stage evaporators, the lithium bromide concentrated solution in the corresponding absorbers is promoted to give off a large amount of heat absorption efficiency of the heat exchange unit by spontaneously maintaining a stable working pressure state. The refrigerant water stored in the second-stage evaporator 62 enters the first-stage evaporator 61 respectively under the supercharging drive of the refrigerant pump 2, the top of the second-stage evaporator 62 carries out spray evaporation, and the refrigerant water circulates and reciprocates.

Driving hot water to enter a heat exchange tube of the generator 3 as a high-temperature heat source, performing heat exchange with the lithium bromide dilute solution on the vacuum side outside the tube in a countercurrent way, heating the dilute solution by using the heat of the high-temperature hot water, and cooling the diluted solution and flowing along the heat exchange tube to the generator 3; the residual hot water is used as a low-temperature heat source, sequentially passes through the heat exchange tubes of the second-stage evaporator 62 and the first-stage evaporator 61, exchanges heat with the refrigerant water at the vacuum side outside the tubes, evaporates the refrigerant water, and provides the refrigerant steam to the corresponding absorber step by step; the heating water backwater passes through the heat exchange tube bundles of the second-stage absorber 52, the heat exchange tube bundles of the first-stage absorber 51 and the heat exchange tube bundles of the condenser 4 in sequence, absorbs the absorption heat released by the refrigerant steam absorbed by the concentrated solution of lithium bromide at the vacuum side in the evaporator step by step, and compared with the existing single-stage absorber, the heating water absorbs the heat step by step, carries out temperature rise twice, reduces the heat loss in the heating water conveying process, finally absorbs the condensation latent heat of the condenser 4, and the obtained heating water supply and the imported heating water backwater generate larger inlet-outlet temperature difference.

Embodiment two:

The first embodiment is the same, except that the water inlet and outlet of the unit connection is different and the principle inside the evaporator and absorber is different.

The waterway side of the heat exchange tube of the generator 3 is connected with a high-temperature heat source water inlet and a high-temperature heat source water outlet; the waterway sides of the heat exchange tubes of the second-stage evaporator 62 and the first-stage evaporator 61 are respectively connected with a cold water backwater inlet and a cold water supply outlet; the heat exchange tube waterway side of the second-stage absorber 52 is connected with the cooling water inlet and the heat exchange tube waterway side of the first-stage absorber 51 respectively through pipelines, and the heat exchange tube waterway side of the condenser 4 is connected with the heat exchange tube waterway side of the first-stage absorber 51 and the cooling water outlet respectively through pipelines.

The inside of the unit is in a vacuum state, so that a low-pressure environment can be formed, the refrigerant water can be evaporated at a low temperature, and the refrigerant water is sprayed into the first-stage evaporator 61 and the second-stage evaporator 62 from the top in parallel by the driving of the refrigerant pump 2, and rapidly expands and evaporates in the evaporators. The cold water backwater sequentially passes through the heat exchange tubes of the second-stage evaporator 62 and the first-stage evaporator 61, the heat required by the evaporation of the refrigerant water in the evaporators is released step by step, and compared with the single-stage evaporator, the cold water backwater is cooled twice to obtain cold water supply; the cooling water pipeline sequentially passes through the second-stage absorber 52, the first-stage absorber 51 and the water channel side of the heat exchange pipe of the condenser 4 to exchange heat, and the lithium bromide solution on the vacuum side outside the heat exchange pipe of the second-stage absorber 51 and the first-stage absorber 52 is cooled, so that the refrigerant vapor absorption capacity of the lithium bromide solution is strong and inversely proportional to the temperature of the lithium bromide solution within a certain range. The capability of absorbing the refrigerant steam of the cooled lithium bromide solution at the vacuum side is enhanced, so that the working pressure of the refrigerant steam flow pipelines between the absorbers and the evaporators at each level is automatically maintained to be the same, the vaporization quantity of the refrigerant water in the evaporators at each level can be increased, and a large amount of heat of cold water backwater is absorbed, so that the cold water backwater and cold water supply generate larger water inlet and outlet temperature difference, and the aim of cooling is better achieved.

Embodiment III:

As shown in fig. 3, the unit improves the generator and the solution circulation loop on the basis of the first embodiment, the evaporator, the absorber and the generator of the unit all adopt two-stage heat exchange, and the condenser adopts single-stage heat exchange. The unit is composed of two independent solution circulation loops and a refrigerant pipeline.

The generator is a two-stage heat exchange structure comprising a first-stage generator 31 and a second-stage generator 32, and the solution circulation loop is composed of two independent loops: the first-stage generator 31, the first-stage solution heat exchanger 71, the first-stage solution pump 11 and the first-stage absorber 51 are connected through pipelines to form a first-stage solution circulation loop; the second-stage generator 32, the second-stage solution heat exchanger 72, the second-stage solution pump 12 and the second-stage absorber 52 are connected by pipelines to form a second-stage solution circulation loop;

The liquid communication pipeline is not arranged between the first-stage absorber 51 and the second-stage absorber 52, lithium bromide solutions of the two circulation loops are not communicated with each other, have different concentrations and are mutually independent, so that the working pressures of the absorber and the generator on the waterway side and the absorber and the generator on the vacuum side in the loops can be better adapted; the first stage generator 31 and the second stage generator 32 are respectively connected to the condenser 4 to respectively form a third stage refrigerant vapor flow line and a fourth stage refrigerant vapor flow line.

The first stage generator 31 and the second stage generator 32 are respectively a heat exchange chamber, and a plurality of rows of heat exchange tube bundles are arranged in each heat exchange chamber, wherein each heat exchange tube bundle consists of a plurality of horizontally arranged heat exchange tubes. The inside of the heat exchange tube is a waterway side, the outside of the heat exchange tube is a vacuum side, and spray devices are arranged above the heat exchange tube.

The first heat exchange tube bundle 81 inside the first-stage generator 31 is connected with the second heat exchange tube bundle 82 inside the second-stage generator 32 through a pipeline, the two heat exchange tube bundles are respectively connected with a high-temperature heat source water inlet and a high-temperature heat source water outlet, and the seventh heat exchange tube bundle 112 inside the second-stage evaporator 62 and the sixth heat exchange tube bundle 111 inside the first-stage evaporator 61 are respectively connected with a low-temperature heat source water inlet and a low-temperature heat source water outlet; the fifth heat exchange tube bundle 102 in the second-stage absorber 52 is respectively connected with a heating water return inlet and the fourth heat exchange tube bundle 101 in the first-stage absorber 51 through pipelines, and the third heat exchange tube bundle 9 in the condenser 4 is respectively connected with the fourth heat exchange tube bundle 101 in the first-stage absorber 51 and a heating water supply outlet through pipelines.

At this time, the invention adopts a two-stage generator, and the operation modes of two solution circulation loops are as follows: driving hot water as a high-temperature heat source to enter a first heat exchange tube bundle 81 inside the first-stage generator 31 and a second heat exchange tube bundle 82 inside the second-stage generator 32, respectively entering lithium bromide dilute solution at the outer vacuum side of the tubes into the first-stage generator 31 and the second-stage generator 32, heating by a driving heat source in each-stage generator, generating refrigerant steam, and concentrating the lithium bromide dilute solution into a concentrated solution; the concentrated solution is cooled by the solution heat exchangers 71 and 72 and then enters the first-stage absorber 51 and the second-stage absorber 52 respectively through the top spraying device (at the moment, the first-stage absorber 51 and the second-stage absorber 52 are independent absorbers which are not communicated with each other) to absorb the refrigerant steam from the corresponding first-stage evaporator 61 and second-stage evaporator 62, the concentrated solution is changed into a dilute solution, and heat can be released in the absorption process; the diluted solution is heated by the first-stage solution pump 11 and the second-stage solution pump 12 through the first-stage solution heat exchanger 71 and the second-stage solution heat exchanger 72, and then returned to the first-stage generator 31 and the second-stage generator 32, respectively, under the supercharging drive, so as to complete two independent solution circulation. The heat loads of the two-stage evaporator, the two-stage absorber and the two-stage generator are more balanced by adjusting the working concentrations of the lithium bromide concentrated solution and the lithium bromide diluted solution in the two solution circulation loops, so that the total heat exchange area of the unit is reduced.

Driving hot water to enter a first heat exchange tube bundle 81 and a second heat exchange tube bundle 82 in the first stage generator 31 and the second stage generator 32 as high-temperature heat sources, performing heat exchange with the lithium bromide dilute solution on the outer vacuum side of the tubes in a countercurrent way, heating the dilute solution by using the heat of the high-temperature hot water, and cooling and then flowing out of the second stage generator 32 along the heat exchange tubes; the driving heat source is in countercurrent with the lithium bromide solution after passing through the first-stage generator 31, and enters the second-stage generator 32 after heat exchange, so that irreversible heat loss in the heat transfer process can be reduced, the driving heat source is cooled step by step, and at the moment, the first-stage generator 31 and the second-stage generator 32 adopt heat sources of the same kind but different temperatures, so that the adaptability of a unit to the heat source is enhanced, and the heat energy utilization rate is improved. The device of the two-stage generator enables the temperature reduction amplitude of the driving hot water in the generator to be increased, the content of lithium bromide concentrated solution generated on the vacuum side of the device is also increased, the capacity of absorbing refrigerant steam is increased, the released absorption heat is increased, heating water absorbs heat step by step, the temperature is raised twice, and the heat loss in the heating water conveying process is reduced. Meanwhile, the two independent solution circulation loops are arranged, the working concentrations of the lithium bromide concentrated solution and the lithium bromide diluted solution in the two solution circulation loops are adjusted, the temperature conditions of the absorber and the generator on the waterway side and the working pressures of the absorber and the generator on the vacuum side in the loops can be better adapted, the heat loads of the two-stage evaporator, the two-stage absorber and the two-stage generator are more balanced, and a better heat exchange effect is achieved. The residual water is used as a low-temperature heat source, sequentially passes through a seventh heat exchange tube bundle 112 in the second-stage evaporator 62 and a sixth heat exchange tube bundle 111 in the first-stage evaporator 61, and provides refrigerant steam to the corresponding absorber step by step; the heating water backwater sequentially passes through the fifth heat exchange tube bundle 102 in the second-stage absorber 52, the fifth heat exchange tube bundle 101 in the first-stage absorber 51 and the third heat exchange tube bundle 9 in the condenser 4, the absorption heat in the absorber and the condensation heat in the condenser are absorbed step by step, and the obtained heating water supply and the imported heating water backwater generate larger inlet-outlet temperature difference.

Embodiment four:

The difference with the three phases of the embodiment is that the water inlet and outlet of the unit connection are different and the principle inside the evaporator and the absorber is different.

The first heat exchange tube bundle 81 in the first-stage generator 31 is connected with the second heat exchange tube bundle 82 in the second-stage generator 32 through a pipeline, the two heat exchange tube bundles are respectively connected with a high-temperature heat source water inlet and a high-temperature heat source water outlet, and the seventh heat exchange tube bundle 112 in the second-stage evaporator 62 and the sixth heat exchange tube bundle 111 in the first-stage evaporator 61 are respectively connected with a cold water return water inlet and a cold water supply outlet; the fifth heat exchange tube bundle 102 in the second-stage absorber 52 is respectively connected with a cooling water inlet and the fourth heat exchange tube bundle 101 in the first-stage absorber 51 through pipelines, and the third heat exchange tube bundle 9 in the condenser 4 is respectively connected with the fourth heat exchange tube bundle 101 and a cooling water outlet in the first-stage absorber 51 through pipelines.

Driving hot water to enter a first heat exchange tube bundle 81 and a second heat exchange tube bundle 82 in the first stage generator 31 and the second stage generator 32 as high-temperature heat sources, performing heat exchange with the lithium bromide dilute solution on the outer vacuum side of the tubes in a countercurrent way, heating the dilute solution by using the heat of the high-temperature hot water, and cooling and then flowing out of the second stage generator 32 along the heat exchange tubes; the device of the two-stage generator increases the temperature reduction amplitude of the driving hot water in the generator, increases the content of the lithium bromide concentrated solution generated on the vacuum side, simultaneously increases the capacity of the lithium bromide concentrated solution for absorbing the refrigerant steam after the temperature reduction of the cooling water in the absorber (the capacity of the lithium bromide solution for absorbing the water steam is in direct proportion to the concentration and in inverse proportion to the temperature), and increases the capacity of the lithium bromide concentrated solution for absorbing the refrigerant steam. Meanwhile, the two independent solution circulation loops are arranged, the working concentrations of the lithium bromide concentrated solution and the lithium bromide diluted solution in the two solution circulation loops are adjusted, the temperature conditions of the absorber and the generator on the waterway side and the working pressures of the absorber and the generator on the vacuum side in the loops can be better adapted, the heat loads of the two-stage evaporator, the two-stage absorber and the two-stage generator are more balanced, and a better heat exchange effect is achieved. The cold water backwater sequentially passes through the heat exchange tubes of the second-stage evaporator 62 and the first-stage evaporator 61, and the cold water releases heat step by step to cool down for two times, so that heat loss in the cold water conveying process is reduced; the cooling water sequentially passes through the heat exchange tube bundles of the second-stage absorber 52, the heat exchange tube bundles of the first-stage absorber 51 and the heat exchange tube bundles of the condenser 4, and the lithium bromide concentrated solution is cooled in each-stage absorber, so that the corresponding evaporators continuously generate refrigerant steam, and heat in cold water is absorbed again; the obtained cold water supply and cold water return generate larger inlet-outlet temperature difference. And cooling the refrigerant steam in the condenser, and enabling the generated refrigerant water to enter a refrigerant pipeline to continue the evaporation heat absorption cycle.

It can be seen that the scheme of the two-stage generator, the two-stage evaporator and the two-stage absorber is adopted in the unit, so that heating water or cold water can generate larger water inlet and outlet temperature difference.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.

Claims (10)

1. The efficient hot water type lithium bromide absorption unit is characterized by comprising an evaporator, an absorber, a generator and a condenser, wherein the evaporator, the absorber and the generator are subjected to two-stage heat exchange, the condenser (4) is subjected to single-stage heat exchange, the unit mainly comprises two independent solution circulation loops and a refrigerant pipeline, and the first-stage generator (31), the first-stage solution heat exchanger (71), the first-stage solution pump (11) and the first-stage absorber (51) are connected through pipelines to form a first-stage solution circulation loop; the second-stage generator (32), the second-stage solution heat exchanger (72), the second-stage solution pump (12) and the second-stage absorber (52) are connected through pipelines to form a second-stage solution circulation loop.

2. The unit according to claim 1, characterized in that the condenser (4) is connected to the first stage evaporator (61) by means of a pipe, and the second stage evaporator (62) is connected to the first stage evaporator (61) and the refrigerant pump (2) by means of a pipe, respectively, forming a refrigerant pipe.

3. The unit according to claim 2, characterized in that said first-stage absorber (51) and first-stage evaporator (61) are in communication with each other, constituting a first-stage refrigerant vapor flow path; the second-stage absorber (52) and the second-stage evaporator (62) are communicated with each other to form a second-stage refrigerant vapor flow channel; the first-stage generator (31) and the condenser (4) are communicated with each other to form a third-stage refrigerant steam flow channel; the second-stage generator (32) and the condenser (4) are communicated with each other to form a fourth-stage refrigerant vapor flow passage.

4. The assembly of claim 1, wherein the solutions in the two solution circulation loops are independent of each other and differ in concentration.

5. The unit according to claim 2, characterized in that the refrigerant pump (2) is connected in parallel with the first stage evaporator (61) and second stage evaporator (62) by means of a spraying device.

6. A unit according to claim 3, wherein the refrigerant vapor flow channels of each stage are maintained in a vacuum state, and the working pressures within the first stage refrigerant vapor flow channels are equal, the working pressures within the second stage refrigerant vapor flow channels are equal, the working pressures within the third stage refrigerant vapor flow channels are equal, and the working pressures within the fourth stage refrigerant vapor flow channels are equal.

7. The unit according to claim 2, characterized in that the first stage generator (31), the second stage generator (32), the first stage absorber (51), the second stage absorber (52), the first stage evaporator (61), the second stage evaporator (62) and the condenser (4) are each one heat exchange chamber, in each of which a plurality of rows of heat exchange tube bundles are installed, wherein each heat exchange tube bundle consists of a plurality of horizontally placed heat exchange tubes.

8. The assembly of claim 7, wherein the heat exchange tube is waterway-side and the heat exchange tube is vacuum-side.

9. The unit according to claim 2, characterized in that the first stage generator (31), the second stage generator (32), the first stage absorber (51), the second stage absorber (52), the first stage evaporator (61) and the second stage evaporator (62) are each provided with a spray device above the heat exchange tubes.

10. The unit of claim 1, wherein the driving heat source of the unit is waste water.