Efficient hot water type lithium bromide absorption unit

Abstract

The utility model discloses an efficient hot water type lithium bromide absorption unit, which is characterized in that an evaporator, an absorber and a generator all adopt two-stage heat exchange, a condenser adopts single-stage heat exchange, the unit mainly comprises two independent solution circulation loops and a refrigerant pipeline, and a first-stage generator and a second-stage generator are connected in series through a pipeline. The second-stage absorber, the first-stage absorber and the condenser are connected in series through a pipeline, and the second-stage evaporator and the first-stage evaporator are connected in series through a pipeline. According to the unit, the consumption of high-grade heat energy is reduced or replaced by recovering medium-low temperature waste heat water in a factory, so that the comprehensive utilization efficiency of energy is improved; variable working condition adjustment can be achieved, and adaptability to temperature changes of waste heat water is good; meanwhile, power consumption of the unit can be reduced, and a better heat exchange effect can be achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat heating and refrigeration, and in particular to a high-efficiency hot water type lithium bromide absorption unit. Background Art

[0002] Industrial production processes are often accompanied by the generation of a large amount of medium and low temperature waste heat. Due to the low temperature, it cannot be further utilized by the process. Usually, water cooling or air cooling is used to discharge the heat into the environment, resulting in a waste of heat energy. Therefore, strengthening the recovery and utilization of waste heat is the main way to save energy, which involves the application of various high-efficiency energy-saving equipment, waste heat recovery and utilization equipment and energy-saving technologies. Various lithium bromide absorption heat pumps and chillers based on lithium bromide absorption technology are driven by thermal energy, with lithium bromide solution as the absorbent and water as the refrigerant. They recycle the heat energy of waste hot water to achieve heating and cooling.

[0003] According to the different driving heat sources, they are generally divided into hot water type, steam type and direct-fired absorption units. Under most working conditions, medium and low temperature waste heat exists in the form of condensed water, heat medium water and cooling medium. Among them, hot water with a temperature of ≥90℃ can be used as the driving heat source for hot water absorption heat pumps and chiller generators, and hot water with a lower temperature between 25-50℃ can be used as the low-temperature heat source for hot water absorption heat pump evaporators.

[0004] The existing hot water absorption heat pump and chiller are composed of evaporator, absorber, generator, condenser, solution heat exchanger, solution pump, refrigerant pump, control system and pipes and valves connecting the components. Lithium bromide unit is a kind of equipment that utilizes the low evaporation temperature of water under negative pressure and the increase of water vapor temperature absorbed by lithium bromide-water solution to release heat to the outside to achieve heating and cooling water.

[0005] In practical applications, the existing lithium bromide absorption units can only supply hot water or cold water under a single working condition. Because the principles of cooling and heating are different, if the lithium bromide absorption unit is required to meet the functions of heat pump and cold water, corresponding considerations and settings need to be made during the design. A small number of dual-purpose heat pump lithium bromide chillers can only provide low-temperature hot water while providing cold water. And when waste hot water is used as a driving heat source or a low-temperature heat source for heating, the temperature of the waste hot water fluctuates with the changing working conditions, so the temperature of the waste hot water may sometimes be low. When the temperature of the waste hot water as a driving hot water is low, the temperature rise of the heating water is limited, which may cause the outlet temperature of the heating water to be low and fail to meet the water supply temperature requirements; similarly, the cooling range of the cold water is limited, which may cause the outlet temperature of the cold water to be high and fail to meet the water supply temperature requirements. Therefore, there is currently a lack of efficient lithium bromide absorption units that take into account variable working condition application equipment for hot water and cold water supply. Summary of the invention

[0006] In view of this, the utility model aims to propose a high-efficiency hot water absorption unit to solve the problems of low heat exchange efficiency and variable working condition application of lithium bromide absorption units in the prior art.

[0007] In order to achieve the above object, the technical solution of the utility model is implemented as follows:

[0008] A high-efficiency hot water type lithium bromide absorption unit, the evaporator, absorber and generator all adopt two-stage heat exchange, the condenser adopts single-stage heat exchange, and the unit mainly includes two independent solution circulation loops and a refrigerant pipeline. The two solution circulation loops are independent of each other and can better adapt to the temperature conditions of the absorber and generator water side in their respective loops and the working pressure of the absorber and generator vacuum side.

[0009] The first-stage generator and the second-stage generator are connected in series through pipelines, which improves the thermal energy utilization rate of the generator and also enables the generator to generate steam twice step by step, thereby increasing the absorption heat released; the second-stage absorber, the first-stage absorber and the condenser are connected in series through pipelines; the two-stage absorber releases the absorption heat, and the condenser releases the latent heat of condensation. The series connection gradually heats up the water side of the internal heat exchange pipes of each stage of the absorber and the condenser, thereby increasing the heat exchange efficiency of the unit; the second-stage evaporator and the first-stage evaporator are connected in series through pipelines, and the two-stage evaporator provides sufficient refrigerant steam. The series connection enables the water side of the internal heat exchange pipes of the evaporator to release heat step by step, thereby reducing the heat loss of the evaporator and improving the thermal energy utilization rate of the water side of the heat exchange pipes of the evaporator.

[0010] Furthermore, the solution circulation loop is divided into a first-stage solution circulation loop and a second-stage solution circulation loop, the first-stage solution circulation loop mainly includes a first-stage generator, a first-stage solution heat exchanger, a first-stage solution pump, a first-stage absorber and pipelines; the second-stage solution circulation loop mainly includes a second-stage generator, a second-stage solution heat exchanger, a second-stage solution pump, a second-stage absorber and pipelines.

[0011] Furthermore, the first-stage solution circulation loop and the second-stage solution circulation loop are connected in parallel, and the lithium bromide solutions in the two circulation loops are not interconnected and have different concentrations. By adjusting the working concentrations of the lithium bromide concentrated solution and the dilute solution in the two solution circulation loops, the heat loads of the two-stage evaporator, the two-stage absorber and the two-stage generator are made more balanced, thereby reducing the total heat exchange area of ​​the unit and achieving a better heat exchange effect.

[0012] Furthermore, the condenser is connected to the first-stage evaporator through a pipeline, and the second-stage evaporator is connected to the first-stage evaporator and the refrigerant pump through pipelines, respectively, to form a refrigerant pipeline.

[0013] Furthermore, the refrigerant pump and the first stage evaporator and the second stage evaporator are connected in parallel to form a refrigerant water spray pipeline. The parallel connection mode only requires the installation of one refrigerant pump, which reduces the operating parts of the unit, reduces the power consumption of the unit, and improves the reliability of the unit operation.

[0014] Furthermore, the first-stage absorber and the first-stage evaporator are interconnected to form a first-stage refrigerant vapor flow channel; the second-stage absorber and the second-stage evaporator are interconnected to form a second-stage refrigerant vapor flow channel; the first-stage generator and the condenser are interconnected to form a third-stage refrigerant vapor flow channel; the second-stage generator and the condenser are interconnected to form a fourth-stage refrigerant vapor flow channel.

[0015] Furthermore, the refrigerant vapor flow channels at each stage are kept in a vacuum state, and the internal working pressure of the first-stage refrigerant vapor flow channel is equal, the internal working pressure of the second-stage refrigerant vapor flow channel is equal, the internal working pressure of the third-stage refrigerant vapor flow channel is equal, and the internal working pressure of the fourth-stage refrigerant vapor flow channel is equal.

[0016] Furthermore, 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 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.

[0017] Furthermore, the inside of the heat exchange tube is a water channel side, and the outside of the heat exchange tube is a vacuum side.

[0018] Furthermore, a spray device is provided above the heat exchange tubes 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.

[0019] Compared with the prior art, the high-efficiency hot water absorption heat pump chiller described in the utility model has the following advantages:

[0020] The utility model reduces or replaces the consumption of high-grade thermal energy by recycling the medium and low temperature waste hot water of the factory, thereby improving the comprehensive utilization efficiency of energy; the evaporator, absorber and generator all adopt two-stage heat exchange, and the condenser adopts single-stage heat exchange to reduce the irreversible heat loss in the heat transfer process, improve the performance of the unit, and is more conducive to the structural layout of the unit, which is conducive to reducing the manufacturing cost; at the same time, two independent solution circulation loops are formed, and the lithium bromide solutions of the two circulation loops are not interconnected and have different concentrations, which can better adapt to the temperature conditions of the water channel side of the absorber and the generator in each loop and the working pressure of the vacuum side of the absorber and the generator, and by adjusting the working concentrations of the lithium bromide concentrated solution and the dilute solution of the two solution circulation loops, the heat load of the two-stage evaporator, the two-stage absorber and the two-stage generator is more balanced, the total heat exchange area of ​​the unit is reduced, and a better heat exchange effect is achieved; variable working condition adjustment can be realized, which can be used for waste hot water heating working conditions and waste hot water cooling working conditions, and takes into account the variable working condition application for hot water and cold water supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of Embodiment 1 of the present utility model;

[0022] Figure 2 This is a schematic diagram of Embodiment 2 of the present utility model;

[0023] Figure 3 This is a schematic diagram of Embodiment 3 of the present utility model;

[0024] Figure 4 Schematic diagram of embodiment 4 of the present utility model

[0025] Description of reference numerals:

[0026] Solution pump 1, first-stage solution pump 11, second-stage solution pump 12; refrigerant pump 2; generator 3, first-stage generator 31, second-stage generator 32; condenser 4; first-stage absorber 51, second-stage absorber 52; first-stage evaporator 61, second-stage evaporator 62; solution heat exchanger 7, first-stage solution heat exchanger 71, second-stage solution heat exchanger 72; first heat exchange tube bundle 81, second heat exchange tube bundle 82; third heat exchange tube bundle 9; fourth heat exchange tube bundle 101, fifth heat exchange tube bundle 102; sixth heat exchange tube bundle 111, seventh heat exchange tube bundle 112. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Embodiment 1:

[0029] like Figure 1The evaporator and absorber of this unit adopt two-stage heat exchange, and the generator and condenser adopt single-stage heat exchange. The unit is a vacuum equipment with extremely high airtightness requirements (it can form a low-pressure environment to make the refrigerant water evaporate at low temperature). In order to maintain the vacuum state inside the unit, the unit is equipped with an exhaust device, which can be a mechanical vacuum pump exhaust system or an automatic exhaust system. The exhaust device is not shown in the figure because it does not belong to the application scope of this patent.

[0030] The unit is composed of a solution circulation loop and a refrigerant pipeline. The solution heat exchanger 7 is connected to the generator 3 and the first-stage absorber 51 through pipelines to form a concentrated solution loop. The second-stage absorber 52 is connected to the first-stage absorber 51, the solution pump 1 and the solution heat exchanger 7 to form a dilute solution loop. The dilute solution loop and the concentrated solution loop together form a solution circulation loop. The condenser 4 is connected to the first-stage evaporator 61, and the second-stage evaporator 62 is connected to the first-stage evaporator 61 and the refrigerant pump 2 to form a refrigerant pipeline. The condenser 4 and the first-stage evaporator 61 are unidirectionally connected to form a refrigerant water reflux 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 interconnected to form a refrigerant vapor flow channel. The first-stage absorber 51 and the first-stage evaporator 61 are interconnected to form a first-stage refrigerant vapor flow channel. The second-stage absorber 52 and the second-stage evaporator 62 are interconnected to form a second-stage refrigerant vapor flow channel. The refrigerant vapor flow channels at each level are kept in a vacuum state, and the working pressure inside the refrigerant vapor flow channels at each level is equal.

[0031] 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 multiple rows of heat exchange tube bundles are installed in each heat exchange chamber, wherein each heat exchange tube bundle is composed of multiple heat exchange tubes placed horizontally. The inside of the heat exchange tube is the waterway side, and the outside of the heat exchange tube is the vacuum side. Spraying devices are arranged 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.

[0032] The driving hot water inlet and the driving hot water outlet are respectively connected to the water channel side of the heat exchange tube bundle inside the generator 3; the second-stage absorber 52, the first-stage absorber 51 and the condenser 4 are connected in series through pipelines: the fifth heat exchange tube bundle 102 inside the second-stage absorber 52 is connected to the heating water return and the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 through pipelines, and the third heat exchange tube bundle 9 inside the condenser 4 is connected to the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the heating water supply through pipelines; the second-stage evaporator 62 and the first-stage evaporator 61 are connected in series through pipelines: the waste hot water inlet is connected to the seventh heat exchange tube bundle 112 inside the second-stage evaporator 62, and the waste hot water outlet is connected to the sixth heat exchange tube bundle 111 inside the first-stage evaporator 61; wherein the driving hot water is waste hot water.

[0033] The hot water is driven to enter the heat exchange tube of the generator 3 as a high-temperature heat source. The dilute lithium bromide solution on the vacuum side outside the tube is heated and concentrated by the driven hot water in the generator 3. Refrigerant vapor is generated in the process. The dilute lithium bromide solution becomes a concentrated solution and then flows out. The concentrated solution passes through the solution heat exchanger 7 to release heat and cool down before entering the first-stage absorber 51. It is sprayed from the top to the vacuum side outside the tube of the first-stage absorber 51, absorbs the refrigerant vapor from the first-stage evaporator 61, and releases absorption heat. After the concentrated solution is diluted, it flows out through the solution flow channel and enters the second-stage absorber 52. It absorbs the refrigerant vapor from the second-stage evaporator 62 and releases absorption heat. The lithium bromide solution is further diluted and becomes a dilute solution. The lithium bromide concentrated solution absorbs the refrigerant vapor from the evaporator step by step through the two absorbers, gradually diluting the lithium bromide concentrated solution, releasing absorption heat twice, increasing the heat source of the unit, and reducing the heat loss of the unit under working conditions. Driven by the booster of the solution pump 1, the solution passes through the solution exchanger 7 to exchange heat with the high-temperature lithium bromide concentrated solution, and after the temperature is increased, it enters the generator 3 and is driven by hot water to heat and concentrate, thus completing the solution circulation loop.

[0034] The refrigerant steam generated in the generator 3 enters the condenser 4 through the refrigerant steam flow channel, condenses on the external vacuum side of the third heat exchange tube bundle 9, releases condensation heat, and becomes refrigerant water, which is sprayed into the top of the first-stage evaporator 61 through the refrigerant water return channel. A part of the refrigerant water absorbs the heat in the waste hot water and evaporates on the outside of the sixth heat exchange tube bundle 111 inside the first-stage evaporator 61. The generated refrigerant steam enters the first-stage absorber 51 through the first-stage refrigerant steam flow channel and is absorbed by the lithium bromide concentrated solution. The other part of the refrigerant water that has not evaporated is discharged from the first-stage evaporator. The refrigerant water flows out of the evaporator 61, passes through the refrigerant water circulation pipeline, enters the second-stage evaporator 62 to continue absorbing the heat in the waste hot water and evaporating, and the generated refrigerant vapor enters the second-stage absorber 52 through the second-stage refrigerant vapor flow channel to be absorbed by the solution. The two-stage evaporator can provide refrigerant vapor to the corresponding absorber step by step, and its refrigerant vapor output rate is significantly higher than that of the single-stage evaporator. By spontaneously maintaining a stable working pressure state, it promotes the lithium bromide concentrated solution in the corresponding absorber to absorb the refrigerant vapor and release a large amount of absorption heat, thereby improving the heat exchange efficiency of the unit. The refrigerant water remaining in the second-stage evaporator 62 enters the first-stage evaporator 61 under the boost drive of the refrigerant pump 2, and the top of the second-stage evaporator 62 is sprayed and evaporated, and the refrigerant water circulates back and forth.

[0035] The hot water is driven as a high-temperature heat source to enter the heat exchange tube of the generator 3, and is countercurrently heat-exchanged with the dilute lithium bromide solution on the vacuum side outside the tube. The heat of the high-temperature hot water is used to heat the dilute solution, and after cooling, it flows out of the generator 3 along the heat exchange tube; the waste hot water is used as a low-temperature heat source, and passes through the seventh heat exchange tube bundle 112 and the sixth heat exchange tube bundle 111 inside the second-stage evaporator 62 and the first-stage evaporator 61 in turn, and is heat-exchanged with the refrigerant water on the vacuum side outside the tube, so that the refrigerant water evaporates and provides refrigerant steam to the corresponding absorber step by step; the heating water return water passes through .... The fifth heat exchange tube bundle 102 inside the second-stage absorber 52, the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the third heat exchange tube bundle 9 inside the condenser 4 absorb step by step the absorption heat released by the concentrated lithium bromide solution on the vacuum side of each stage of the evaporator when absorbing the refrigerant vapor. Compared with the existing single-stage absorber, the heating water absorbs heat step by step and is heated twice, thereby reducing the heat loss in the heating water transportation process. Finally, the latent heat of condensation of the condenser 4 is absorbed, and a large inlet and outlet temperature difference is produced between the obtained heating water supply and the imported heating water return water.

[0036] Embodiment 2:

[0037] The same as the first embodiment, the difference lies in that the inlet and outlet water of the unit connection are different and the principles inside the evaporator and absorber are different.

[0038] Under the cold water supply condition: the driving hot water inlet and the driving hot water outlet are respectively connected to the water channel side of the heat exchange tube bundle inside the generator 3; the cold water return is connected to the seventh heat exchange tube bundle 112 inside the second-stage evaporator 62, and the cold water supply is connected to the sixth heat exchange tube bundle 111 inside the first-stage evaporator 61; the fifth heat exchange tube bundle 102 inside the second-stage absorber 52 is connected to the cooling water inlet and the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 through pipelines, and the third heat exchange tube bundle 9 inside the condenser 4 is respectively connected to the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the cooling water outlet through pipelines.

[0039] Since the inside of the unit is in a vacuum state, a low-pressure environment can be formed, so that the refrigerant water can evaporate at a low temperature. The refrigerant water is driven by the refrigerant pump 2 and sprayed in parallel from the top into the first-stage evaporator 61 and the second-stage evaporator 62, and rapidly expands and vaporizes in the evaporator. The cold water return passes through 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 in turn, releasing the heat required for the evaporation of the refrigerant water in the evaporator step by step. Compared with the single-stage evaporator, the cold water return is cooled twice to obtain the cold water supply; the cooling water pipeline passes through the fifth heat exchange tube bundle 102 inside the second-stage absorber 52, the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the third heat exchange tube bundle 9 inside the condenser 4 in turn for heat exchange, cooling the lithium bromide solution on the vacuum side outside the heat exchange tubes of the second-stage absorber 51 and the first-stage absorber 52. Since the lithium bromide solution has a strong ability to absorb refrigerant vapor, and within a certain range, its ability to absorb refrigerant vapor is inversely proportional to the temperature of the lithium bromide solution. The ability of the lithium bromide solution to absorb refrigerant vapor is enhanced after cooling on the vacuum side. In order to spontaneously maintain the same working pressure in the refrigerant vapor flow pipelines between the absorbers and evaporators at each stage, the refrigerant water in the evaporators at each stage will increase its vaporization volume and absorb a large amount of heat from the cold water return water, causing a larger inlet and outlet water temperature difference between the cold water return water and the cold water supply water, thereby better achieving the purpose of cooling.

[0040] Embodiment three:

[0041] like Figure 3 As shown, this unit is based on the first embodiment, the generator and solution circulation loop are improved, the evaporator, absorber and generator of this unit all adopt two-stage heat exchange, and the condenser adopts single-stage heat exchange. The unit consists of two independent solution circulation loops and a refrigerant pipeline.

[0042] The generator is a two-stage heat exchange structure including a first-stage generator 31 and a second-stage generator 32, and the solution circulation loop is 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 by 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;

[0043] There is no liquid connecting pipe between the first-stage absorber 51 and the second-stage absorber 52. The lithium bromide solutions in the two circulation loops are not connected to each other, have different concentrations, and are independent of each other, so as to better adapt to the temperature conditions on the water side of the absorber and the generator in their respective loops and the working pressure on the vacuum side of the absorber and the generator; the first-stage generator 31 and the second-stage generator 32 are respectively connected to the condenser 4, forming the third-stage refrigerant vapor flow pipeline and the fourth-stage refrigerant vapor flow pipeline respectively.

[0044] The first stage generator 31 and the second stage generator 32 are each a heat exchange chamber, and multiple rows of heat exchange tube bundles are installed in each heat exchange chamber, wherein each heat exchange tube bundle is composed of multiple heat exchange tubes placed horizontally. The inside of the heat exchange tube is the waterway side, the outside of the heat exchange tube is the vacuum side, and a spray device is arranged above the heat exchange tube.

[0045] Under the hot water supply condition: the first-stage generator and the second-stage generator are connected in series through pipelines: the first heat exchange tube bundle 81 inside the first-stage generator 31 is connected to the second heat exchange tube bundle 82 inside the second-stage generator 32 through pipelines, and the two heat exchange tube bundles are respectively connected to the driving hot water inlet and the driving hot water outlet; the fifth heat exchange tube bundle 102 inside the second-stage absorber 52 is connected to the heating water return and the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 through pipelines, and the third heat exchange tube bundle 9 inside the condenser 4 is connected to the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the heating water supply through pipelines; the waste hot water inlet is connected to the seventh heat exchange tube bundle 112 inside the second-stage evaporator 62, and the waste hot water outlet is connected to the sixth heat exchange tube bundle 111 inside the first-stage evaporator 61; wherein the driving hot water is waste hot water.

[0046] At this time, the utility model adopts a two-stage generator and two solution circulation loops in operation mode: hot water is driven as a high-temperature heat source to enter the heat exchange tube bundle 81 of the first-stage generator 31 and the heat exchange tube bundle 82 of the second-stage generator 32, and the dilute lithium bromide solution on the vacuum side outside the tube enters the first-stage generator 31 and the second-stage generator 32 respectively, and is heated by the driving heat source in each stage of the generator to generate refrigerant steam, and the dilute lithium bromide solution is concentrated 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 through the top spray device. In the second-stage absorber 52 (at this time, the first-stage absorber 51 and the second-stage absorber 52 are independent absorbers and are not connected to each other), the refrigerant vapor from the corresponding first-stage evaporator 61 and the second-stage evaporator 62 is absorbed, and the concentrated solution becomes a dilute solution, and heat is released during the absorption process; the dilute solution is respectively driven by the first-stage solution pump 11 and the second-stage solution pump 12, and is heated by the first-stage solution heat exchanger 71 and the second-stage solution heat exchanger 72 and returns to the first-stage generator 31 and the second-stage generator 32, completing two independent solution cycles. By adjusting the working concentrations of the lithium bromide concentrated solution and the dilute solution in the two solution circulation loops, the heat load of the two-stage evaporator, the two-stage absorber and the two-stage generator is more balanced, and the total heat exchange area of ​​the unit is reduced.

[0047] The driving hot water as a high-temperature heat source enters the first heat exchange tube bundle 81 inside the first-stage generator 31 and the second heat exchange tube bundle 82 inside the second-stage generator 32, and counter-flows with the lithium bromide dilute solution on the vacuum side outside the tube for heat exchange, and uses the heat of the high-temperature hot water to heat the dilute solution, and flows out of the second-stage generator 32 along the heat exchange tube after cooling down; because the driving heat source counter-flows with the lithium bromide solution after passing through the first-stage generator 31, and enters the second-stage generator 32 after heat exchange, the irreversible heat loss in the heat transfer process can be reduced, and the driving heat source is cooled step by step. At this time, the first-stage generator 31 and the second-stage generator 32 use the same type of heat source but different temperatures, which enhances the adaptability of the unit to the heat source and improves the thermal energy utilization rate. The two-stage generator device increases the cooling range of the driving hot water in the generator, and the content of the lithium bromide concentrated solution generated on the vacuum side is also increased, the ability to absorb refrigerant vapor is increased, and the absorption heat released is increased. The heating water absorbs heat step by step, and is heated twice, which reduces the heat loss in the heating water transportation process. At the same time, it has two independent solution circulation loops. By adjusting the working concentrations of lithium bromide concentrated solution and dilute solution in the two solution circulation loops, it can better adapt to the temperature conditions of the water side of the absorber and generator in each loop and the working pressure of the vacuum side of the absorber and generator, so that the heat load of the two-stage evaporator, the two-stage absorber and the two-stage generator is more balanced, and a better heat exchange effect is achieved. The waste hot water, as a low-temperature heat source, passes through 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 in turn, and provides refrigerant steam to the corresponding absorber step by step; the heating water return water passes through the fifth heat exchange tube bundle (102) inside the second-stage absorber 52, the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the third heat exchange tube bundle 9 inside the condenser 4 in turn, absorbing the absorption heat in the absorber and the condensation heat in the condenser step by step, and the obtained heating water supply and the imported heating water return water have a large inlet and outlet temperature difference.

[0048] Embodiment 4:

[0049] The same as the third embodiment, the difference lies in the different inlet and outlet water of the unit connection and the different principles inside the evaporator and absorber.

[0050] Under the cold water supply condition: the first heat exchange tube bundle 81 inside the first-stage generator 31 is connected to the second heat exchange tube bundle 82 inside the second-stage generator 32 through pipelines, and the two heat exchange tube bundles are respectively connected to the driving heat source inlet and the driving heat source outlet; the cold water return is connected to the seventh heat exchange tube bundle 112 inside the second-stage evaporator 62, and the cold water supply is connected to the sixth heat exchange tube bundle 111 inside the first-stage evaporator 61; the fifth heat exchange tube bundle 102 inside the second-stage absorber 52 is respectively connected to the cooling water inlet and the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 through pipelines, and the third heat exchange tube bundle 9 inside the condenser 4 is respectively connected to the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the cooling water outlet through pipelines.

[0051] The hot water is driven as a high-temperature heat source to enter the first heat exchange tube bundle 81 inside the first-stage generator 31 and the second heat exchange tube bundle 82 inside the second-stage generator 32, and is countercurrently heat-exchanged with the lithium bromide dilute solution on the vacuum side outside the tubes. The heat of the high-temperature hot water is used to heat the dilute solution, and after cooling, it flows out of the second-stage generator 32 along the heat exchange tubes. The two-stage generator device increases the cooling amplitude of the driving hot water in the generator, and the content of the lithium bromide concentrated solution generated on the vacuum side is also increased. At the same time, after being cooled by cooling water in the absorber (the ability of the lithium bromide solution to absorb water vapor is proportional to the concentration and inversely proportional to the temperature), the ability of the lithium bromide concentrated solution to absorb refrigerant vapor is enhanced. In order to spontaneously maintain the same working pressure of the refrigerant vapor flow pipeline between the absorbers and evaporators at each stage, the refrigerant water in the evaporators at each stage will increase its vaporization amount, absorb a large amount of heat from the cold water return water, and produce a large inlet and outlet water temperature difference between the cold water return water and the cold water supply water, so as to better achieve the purpose of cooling. At the same time, it has two independent solution circulation loops. By adjusting the working concentrations of lithium bromide concentrated solution and dilute solution in the two solution circulation loops, it can better adapt to the temperature conditions of the water side of the absorber and generator in each loop and the working pressure of the vacuum side of the absorber and generator, so that the heat load of the two-stage evaporator, the two-stage absorber and the two-stage generator is more balanced, and a better heat exchange effect is achieved. The cold water return water passes through 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 in turn. The cold water releases heat step by step, and the temperature is lowered twice, reducing the heat loss in the cold water transportation process; the cooling water passes through the fifth heat exchange tube bundle 102 inside the second-stage absorber 52, the fourth heat exchange tube bundle 101 inside the first-stage absorber 51 and the third heat exchange tube bundle 9 inside the condenser 4 in turn, cooling the lithium bromide concentrated solution in each stage of the absorber, so that the corresponding evaporators at each stage continue to generate refrigerant vapor and absorb the heat in the cold water again; the obtained cold water supply and cold water return water have a large inlet and outlet temperature difference. The refrigerant vapor is cooled in the condenser to generate refrigerant water which enters the refrigerant pipeline to continue the evaporation and heat absorption cycle.

[0052] It can be seen that this unit adopts a two-stage generator, two-stage evaporator and two-stage absorber solution, which can produce a larger inlet and outlet water temperature difference for heating water or cooling water.

[0053] Although the utility model is disclosed as above, the utility model is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the utility model. Therefore, the protection scope of the utility model shall be subject to the scope defined by the claims.

Claims

1. A high-efficiency hot water type lithium bromide absorption unit, characterized in that: The evaporator, absorber and generator all adopt two-stage heat exchange, and the condenser (4) adopts single-stage heat exchange. The unit mainly includes two independent solution circulation loops and a refrigerant pipeline. The first-stage generator (31) and the second-stage generator (32) are connected in series through pipelines, the second-stage absorber (52), the first-stage absorber (51) and the condenser (4) are connected in series through pipelines, and the second-stage evaporator (62) and the first-stage evaporator (61) are connected in series through pipelines.

2. The unit according to claim 1, characterized in that: The solution circulation loop is divided into a first-stage solution circulation loop and a second-stage solution circulation loop. The first-stage solution circulation loop mainly comprises a first-stage generator (31), a first-stage solution heat exchanger (71), a first-stage solution pump (11), a first-stage absorber (51) and pipelines; the second-stage solution circulation loop mainly comprises a second-stage generator (32), a second-stage solution heat exchanger (72), a second-stage solution pump (12), a second-stage absorber (52) and pipelines.

3. The unit according to claim 2, characterized in that: The first-stage solution circulation loop and the second-stage solution circulation loop are connected in parallel.

4. The unit according to claim 1, characterized in that: The condenser (4) is connected to the first-stage evaporator (61) through a pipeline, and the second-stage evaporator (62) is connected to the first-stage evaporator (61) and the refrigerant pump (2) through pipelines, respectively, to form a refrigerant pipeline.

5. The unit according to claim 4, characterized in that: The refrigerant pump (2) and the first-stage evaporator (61) and the second-stage evaporator (62) are connected in parallel to form a refrigerant water spray pipeline.

6. The unit according to claim 1, characterized in that: The first-stage absorber (51) and the first-stage evaporator (61) are interconnected to form a first-stage refrigerant vapor flow channel; the second-stage absorber (52) and the second-stage evaporator (62) are interconnected to form a second-stage refrigerant vapor flow channel; the first-stage generator (31) and the condenser (4) are interconnected to form a third-stage refrigerant vapor flow channel; the second-stage generator (32) and the condenser (4) are interconnected to form a fourth-stage refrigerant vapor flow channel.

7. The unit according to claim 6, characterized in that: The refrigerant vapor flow channels at each stage are kept in a vacuum state, and the internal working pressures of the first-stage refrigerant vapor flow channels are equal, the internal working pressures of the second-stage refrigerant vapor flow channels are equal, the internal working pressures of the third-stage refrigerant vapor flow channels are equal, and the internal working pressures of the fourth-stage refrigerant vapor flow channels are equal.

8. The unit according to claim 1, 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 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 heat exchange tubes placed horizontally.

9. The unit according to claim 8, characterized in that: The inside of the heat exchange tube is the water channel side, and the outside of the heat exchange tube is the vacuum side.

10. The unit according to claim 1, characterized in that: Spray devices are provided above the heat exchange tubes of 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).

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