Sorption heat pump and cycle

Description

[0001] The invention relates firstly to a sorption heat pump with gaseous refrigerant and liquid solvent, with an enriched solution and a rich solution, which are single-phase mixtures of the solvent and the refrigerant, with an absorption unit in which a first partial flow of the solvent in a medium-pressure absorber at a medium-pressure level absorbs a medium-pressure partial flow and a second partial flow in a high-pressure absorber at a high-pressure level absorbs a high-pressure partial flow of the refrigerant and thereby releases the heat generated to a heat sink outside the sorption heat pump, with an expeller in which the rich solution from the absorption unit at a low-pressure level absorbs heat from a heat source outside the sorption heat pump and thereby expels the refrigerant, with a throttle valve,which expands the rich solution from high pressure to low pressure after exiting the absorption unit and entering the expeller, and with a pump and a compressor that pump the solvent and refrigerant from low pressure to medium pressure after exiting the expeller. The invention further relates to a sorption cycle in such a sorption heat pump.

[0002] Such a sorption heat pump and such a sorption cycle are known from EP 3 964 770 A1 and EP 3 540 332 A1. There, it is proposed to first pump the solvent and the refrigerant from the low-pressure level to the high-pressure level and convey them to the high-pressure absorber. The medium-pressure partial flow is decoupled upstream of the high-pressure absorber and expanded to the medium-pressure level, so that the solvent initially absorbs only the remaining high-pressure partial flow, and the resulting enriched solution subsequently absorbs the medium-pressure partial flow in the medium-pressure absorber. Task

[0003] The invention is based on the object of reducing the energy requirement to reach the high pressure level.

[0004] The object is achieved by a sorption heat pump according to claim 1 and by a sorption cycle process according to claim 7.

[0005] Such a sorption heat pump according to the invention absorbs heat at a low temperature level and releases it again at a higher level.

[0006] The rich solution cools in the throttle valve, allowing it to absorb the low-temperature heat. The gaseous refrigerant and the liquid solvent are fed separately to the absorption unit.

[0007] In the sorption heat pump according to the invention, the amount of refrigerant compressed in the gaseous state to the high-pressure level is reduced by the amount of the medium-pressure partial flow compared to the prior art. The resulting energy savings exceed the additional energy required to pump the additional mass flow of the enriched solution to the high-pressure level. The additional energy required to pump the solution enriched by the medium-pressure partial flow is lower than the energy required to compress the medium-pressure partial flow.

[0008] A sorption heat pump according to the invention preferably has an intercooler in which the high-pressure partial flow of the refrigerant releases heat at the intermediate pressure level. Many heat pump applications require two-stage refrigerant compression and intermediate cooling of the vapor between the compressors to achieve the required pressure ratio without the refrigerant vapor becoming excessively hot during compression. In particular, the enriched solution can absorb heat at the high-pressure level in the intercooler. In such a sorption heat pump according to the invention, the enriched solution cools the high-pressure partial flow and makes the absorbed heat available in the high-pressure absorber for the heat sink.

[0009] Preferably, a sorption heat pump according to the invention comprises a solution heat exchanger in which one of the partial streams absorbs heat from the rich solution at the high-pressure level. The absorbed heat is then available in the medium-pressure absorber for the heat sink. In particular, the solvent can absorb the heat at the medium-pressure level.

[0010] Preferably, a sorption heat pump according to the invention has an additional absorber parallel to the high-pressure absorber, in which one of the partial streams absorbs heat from the rich solution at the high-pressure level. If the spread—i.e., the temperature difference between the heat transfer medium's inlet and outlet from the sorption heat pump—at the heat sink is significantly greater than at the heat source, the heat transfer medium of the heat sink can be preheated to a medium temperature level in the medium-pressure absorber. The solution enriched in the medium-pressure absorber is thus cooled almost to the inlet temperature of the heat sink. Before entering the high-pressure absorber, it is heated in such an inventive sorption heat pump to the outlet temperature of the heat sink. In particular, the enriched solution can absorb heat at the high-pressure level.

[0011] In a sorption heat pump according to the invention, the medium-pressure absorber and / or the high-pressure absorber are preferably plate heat exchangers. Such absorbers are technically simple, low-maintenance, and are available cost-effectively in a wide variety of designs on the market.

[0012] In a sorption heat pump according to the invention, the solvent is preferably water and the refrigerant is ammonia. Water and ammonia are natural substances and have proven effective in refrigeration technology.

[0013] According to claim 7, the sorption cycle according to the invention runs in a sorption heat pump according to the invention and is equally characterized by the advantages thereof described above. Preferably, in a sorption cycle according to the invention, a heat transfer medium of the heat sink is divided into two parallel partial streams, and the heat generated when absorbing the medium-pressure partial stream is transferred to a first of the partial streams and the heat generated when absorbing the high-pressure partial stream is transferred to a second of the partial streams, and the partial streams are then recombined. With very different spreads at the heat source and the heat sink, in such a sorption cycle according to the invention as large a medium-pressure partial stream as possible is absorbed at the medium-pressure level, and the heat generated thereby is transferred to the heat transfer medium of the heat sink, for example to generate steam there.To prevent the relatively dry refrigerant from becoming saturated with solvent in the medium-pressure absorber, only as much refrigerant is added to the medium-pressure absorber as can be absorbed. Only the remaining refrigerant is sent to the high-pressure absorber.

[0014] Alternatively, in a sorption cycle process according to the invention, the heat generated during the absorption of the medium-pressure partial flow is preferably transferred to a heat transfer medium of the heat sink, followed by the heat generated during the absorption of the high-pressure partial flow. If the spread at the heat sink is much greater than at the heat source, the heat transfer medium of the heat sink is preheated in the medium-pressure absorber and only heated to the desired initial temperature in the high-pressure absorber.

[0015] In a sorption cycle process according to the invention, the solvent is preferably divided into a first partial stream and a second partial stream. The first partial stream then no longer needs to be pumped to the high-pressure level after absorbing the medium-pressure partial stream. Examples of implementation

[0016] The invention is explained below using exemplary embodiments. Fig. 1 shows a first sorption heat pump according to the invention, Fig. 2 shows a second sorption heat pump according to the invention and Fig. 3 shows a third sorption heat pump according to the invention.

[0017] The Figure 1The first sorption heat pump 1 according to the invention shown has an absorption unit 2, a throttle valve 3, an expeller 4, a separator 5, a compressor 6, a pump 7 and pipes 8 which connect the aforementioned in this order to form a circularly closed system, wherein the compressor 6 is arranged in a refrigerant branch 9 and the pump 7 is arranged in a solvent branch 10 running parallel thereto from the separator 5 to the absorption unit 2.

[0018] In a cycle of a sorption cycle process according to the invention with ammonia (NH 3 ) as refrigerant 11 in water as solvent 12, a flow of 3.3 kg / s of solvent 12 absorbs a flow of 3.2 kg / s of refrigerant 11 in the absorption unit 2 and releases heat output to a heat sink. Feed water entering the absorption unit 2 at 100 °C as the heat transfer medium 13 of the heat sink exits the absorption unit 2 as saturated steam at 110 °C. A flow of rich solution 14 exiting the absorption unit 2 at 6.5 kg / s at a high pressure of 48 bar at 87 °C is expanded by the throttle valve 3 to a low pressure of 6 bar and heated to 64 °C in the expeller 4 from a heat source with an output of 2610 kW. The heat transfer medium 15 of the heat source entering the expeller 4 at 70 °C is cooled to 30 °C.From the subsequent separator 5, the flow of solvent 12 is pumped by the pump 7 and the flow of refrigerant 11 is pumped by the compressor 6, each to a medium pressure level of 22 bar and conveyed into the absorption unit 2.

[0019] The absorption unit 2 has a medium-pressure absorber 16 and a high-pressure absorber 17. The heat transfer medium 13 of the heat sink is initially divided into two partial streams before entering the medium-pressure absorber 16 and the high-pressure absorber 17. The partial streams flow through the medium-pressure absorber 16 and the high-pressure absorber 17 in parallel, and after exiting them, the partial streams are recombined. The refrigerant 11 entering the absorption unit 2 at the medium-pressure level of 160 °C is initially divided into a medium-pressure partial stream 18 and a high-pressure partial stream 19. In the medium-pressure absorber 16, a first partial stream 50 of the solvent 12 absorbs the medium-pressure partial stream 18 and transfers a heating output of 303 kW to the heat transfer medium 13 of the heat sink.

[0020] The absorption unit 2 has a medium-pressure separator 20, an intermediate pump 21, a throttle valve 22, and an intermediate compressor 23. An enriched solution 24 emerging from the medium-pressure absorber 16 at 110 °C initially separates unabsorbed refrigerant 11 in the medium-pressure separator 20 and is pumped by the intermediate pump 21 in a second partial flow 51 to the high-pressure level and at 3.7 kg / s into the high-pressure absorber 17. The refrigerant 11 from the medium-pressure separator 20 is combined with the high-pressure partial flow 19 via the throttle valve 22, and together with this, is also compressed to the high-pressure level in the intermediate compressor 23, where it is heated from 84 °C to 155 °C and fed into the high-pressure absorber 17 at 2.8 kg / s.

[0021] The absorption unit 2 has an intercooler 25 and a solution heat exchanger 26. In the intercooler 25, the high-pressure partial stream 19 of the refrigerant 11 at the medium-pressure level transfers heat to the enriched solution 24 at the high-pressure level, heating it to 126 °C. In the solution heat exchanger 26, the solvent 12 at the medium-pressure level absorbs heat from the rich solution 14 at the high-pressure level.

[0022] The expeller 4, the medium pressure absorber 16, the high pressure absorber 17, the intercooler 25 and the solution heat exchanger 26 are plate heat exchangers.

[0023] The Figure 2The second sorption heat pump 27 according to the invention shown and the sorption cycle process according to the invention taking place therein essentially correspond to the first sorption heat pump 1. In one cycle, a flow of 6.7 kg / s of the solvent 29 absorbs a flow of 3.9 kg / s of the coolant 30 in the absorption unit 28 of the second sorption heat pump 27. The heat transfer medium 31 of the heat sink enters the absorption unit 28 at 60 °C. A flow of rich solution 32 emerging from the absorption unit 28 at 11.2 kg / s at a pressure below 52 °C at a high pressure level of 45 bar is expanded by the throttle valve 33 to a low pressure of 7.3 bar and heated to 38 °C in the expeller 34 with an output of 4130 kW. The heat carrier 35 of the heat source entering the expeller 34 at below 40 °C is cooled to 35 °C.From the subsequent separator 36, the flow of solvent 29 is pumped by the pump 37 and the flow of refrigerant 30 is pumped by the compressor 38, each to a medium pressure level of 28 bar and conveyed into the absorption unit 28.

[0024] Unlike the first sorption heat pump 1, the heat transfer medium 31 of the heat sink is first preheated to 78 °C in the medium-pressure absorber 39 with a heating capacity of 2047 kW and then further heated to the outlet temperature in the high-pressure absorber 40 with a heating capacity of 3464 kW. In addition, the second sorption heat pump 27 has an additional absorber 41 and another solution heat exchanger 42.

[0025] The high-pressure partial flow 44 of refrigerant 30 exiting the intermediate compressor 43 at 155 °C and the enriched solution 45 are split upstream of the high-pressure absorber 40 and fed in parallel into two partial flows through the high-pressure absorber 40 and the additional absorber 41. The respective exiting partial flows of the rich solution 32 are then recombined. The partial flow of the enriched solution 45 in the additional absorber 41 is controlled by a throttle valve 46. Downstream of the intermediate pump 47, the flow of the enriched solution 45 exiting the medium-pressure absorber 39 at 7.3 kg / s below 63 °C is first heated in the additional solution heat exchanger 42 by the rich solution 32 at the high-pressure level to 97 °C.The enriched solution 45 is then divided, controlled by two throttle valves 48 in partial flows of 3.65 kg / s each, heated in parallel in the intercooler 49 to 112 °C and in the additional absorber 41 to 107 °C, recombined and fed below 110 °C into the high pressure absorber 40 and the additional absorber 41.

[0026] The Figure 3 The third sorption heat pump 52 according to the invention shown and the sorption cycle process according to the invention taking place therein essentially correspond to the second sorption heat pump 27. Deviating from this, the solvent 53 is divided into a first partial stream 54 and a second partial stream 55.

[0027] The first partial stream 54 is pumped to the medium-pressure level by a first pump 56 and conveyed to the medium-pressure absorber 57. Upstream of the medium-pressure absorber 57, the first partial stream 54 of the solvent 53 releases heat from the rich solution 59 in a solution heat exchanger 58 from the medium-pressure absorber 57 and from the high-pressure partial stream 61 in the intercooler 60.

[0028] The second partial stream 55 is pumped to the high-pressure level by a second pump 62 and conveyed to the high-pressure absorber 63 and the additional absorber 64. At the high-pressure level, the second partial stream 55 absorbs heat from the rich solution 66 from the high-pressure absorber 63 and the additional absorber 64 in another solution heat exchanger 65.

[0029] The rich solution 66 from the high-pressure absorber 63 and the additional absorber 64 is first expanded to the medium-pressure level in an intermediate throttle valve 67, combined with the rich solution 59 from the medium-pressure absorber and only then expanded to the low-pressure level in the throttle valve 68.

[0030] In the figures are 1Sorption heat pump 2Absorption unit 3Throttle valve 4Extractor 5Separator 6Compressor 7Pump 8Pipe 9Refrigerant branch 10Solvent branch 11Refrigerant 12Solvent 13Heat transfer medium of the heat sink 14Rich solution 15Heat transfer medium of the heat source 16Medium-pressure absorber 17High-pressure absorber 18Medium-pressure partial flow 19High-pressure partial flow 20Medium-pressure separator 21Intermediate pump 22Throttle valve 23Intermediate compressor 24Enriched solution 25Intermediate cooler 26Solution heat exchanger 27Sorption heat pump 28Absorption unit 29Solvent 30Refrigerant 31Heat transfer medium of the heat sink 32Rich solution 33Throttle valve 34Extractor 35Heat transfer medium of the heat source 36Separator 37Pump 38Compressor 39Medium-pressure absorber 40High-pressure absorber 41Additional absorber 42Further solution heat exchanger 43Intermediate compressor 44High-pressure partial stream 45Enriched solution 46Throttle valve 47Intermediate pump 48Throttle valve 49Intermediate cooler 50First partial stream of the solvent 51Second partial stream of the solvent52Sorption heat pump 53Solvent 54First partial stream of the solvent 55Second partial stream of the solvent 56First pump 57Medium-pressure absorber 58Solution heat exchanger 59Rich solution 60Intermediate cooler 61High-pressure partial stream 62Second pump 63High-pressure absorber 64Additional absorber 65Solution heat exchanger 66Rich solution 67Intermediate throttle valve 68Throttle valve

Claims

1. A sorption heat pump (1, 27, 52) - with a gaseous refrigerant (11, 30) and a liquid solvent (12, 29, 53), - with a enriched solution (24, 45) and a rich solution (14, 32, 59, 66), which are one phase mixes of the solvent (12, 29, 53) and the refrigerant (11, 30), - with an absorption unit (2, 28) in which a first partial flow (50, 54) of the solvent (12, 29, 53) absorbs a medium-pressure partial flow (18) of the refrigerant (11, 30) in a medium-pressure absorber (16, 39, 57) at a medium pressure level, and a second partial flow (51, 55) of the solvent (12, 29, 53) absorbs a high-pressure partial flow 19, 44) of the refrigerant (11, 30) in a high-pressure absorber (17, 40, 63) at a high-pressure level, and wherein the first partial flow and the second partial flow emit respective absorption generated heat to a heat sink outside of the sorption heat pump (1, 27, 52), - with an expeller (4, 34) in which the rich solution (14, 32) from the absorption unit (2, 28) absorbs heat at a low-pressure level from a heat source outside of the sorption heat pump (1, 27, 52) and thus expels the refrigerant (11, 30), - with an expansion valve (3, 33, 68) which expands the rich solution (14, 32) from the high-pressure level to the low-pressure level after exiting the absorption unit (2, 28) and before entering the expeller (4, 34), and - with a pump (7, 37, 56) and a compressor (6, 38) that pump the solvent (12, 29) and the refrigerant (11, 30) from the low-pressure level to the medium pressure level after exiting the expeller (4, 34), - with an intermediary compressor (23, 43) that compresses the high-pressure partial flow (19, 44) of the refrigerant (11, 30) from the medium pressure level to the high-pressure level and that feeds the high-pressure partial flow of the refrigerant at the high-pressure level into the high-pressure absorber (17, 40, 63), characterized by an intermediary pump (21, 47) that pumps the enriched solution (24, 45) exiting from the medium pressure absorber (16, 39, 57) to the high-pressure level and feeds the enriched solution at the high-pressure level into the high-pressure absorber (17, 40, 63).

2. The sorption heat pump (1, 27, 52) according to the preceding claim, characterized by an intercooler (25, 49, 60) in which the high-pressure partial flow (19, 44) of the refrigerant (11, 30) emits heat at the medium pressure level in particular to the enriched solution (24, 45) at the high-pressure level.

3. The sorption heat pump (1, 27 ,52) according to one of the preceding claims, characterized by a solution heat exchanger (26, 58, 65) in which one of the partial flows (50, 51, 54, 55) absorbs heat from the rich solution (14, 32, 66) at the high-pressure level.

4. The sorption heat pump (27, 52) according to one of the preceding claims, characterized by an additional absorber (41, 64) arranged parallel to the high-pressure absorber (17, 40, 63), wherein one of the partial flows (50, 51, 54, 55) absorbs heat at the high-pressure level in the additional absorber.

5. The sorption heat pump (1, 27, 52) according to one of the preceding claims, characterized in that the medium pressure absorber (16, 39, 57) and / or the high-pressure absorber (17, 40, 63) are plate heat exchangers.

6. The sorption heat pump (1, 27 52) according one of the preceding claims, characterized in that the solvent (12, 29, 53) is water and the refrigerant (11, 30) is ammonia.

7. A sorption cycle of the sorption heat pump according to claim 1 - with a gaseous refrigerant (11, 30) and a liquid solvent (12, 29, 53), - with a enriched solution (24, 45) and a rich solution (14, 32, 59, 66), which are one phase mixes of the solvent (12, 29, 53) and the refrigerant (11, 30), - wherein a first partial flow (50, 54) of the solvent (12, 29, 53) absorbs a medium-pressure partial flow (18) of the refrigerant (11, 30) at a medium pressure level and a second partial flow (51, 55) of the solvent (12, 29, 53) absorbs a high-pressure partial flow (19, 44) of the refrigerant (11, 30) at a high-pressure level, and wherein the first partial flow and the second partial flow emit respective absorption generated heat to a heat sink outside of the sorption cycle, - wherein the rich solution (14, 32, 59, 66) generated by absorbing the refrigerant (11, 30) is expanded to a low-pressure level and absorbs heat from a heat source outside of the sorption cycle and thus expels the refrigerant (11, 30), - wherein the solvent (12, 29) and the refrigerant (11, 30) are pumped from the low-pressure level to the medium pressure level, - wherein only the high-pressure partial flow (19, 44) of the refrigerant (11, 30) is compressed from the medium pressure level to the high-pressure level, characterized in that the solution (24, 45) enriched by the medium pressure partial flow (18) is pumped from the medium pressure level to the high-pressure level.

8. The sorption cycle according to the preceding claim, characterized in that a heat carrier (13) of the heat sink is divided into two partial flows run in parallel wherein heat generated by absorbing the medium pressure partial flow (18) is emitted to a first partial flow of the two partial flows of the heat carrier (13) and heat generated by absorbing the high-pressure partial flow (19, 44) is emitted to a second partial flow of the partial flows of the heat carrier (13) and wherein the partial flows of the heat carrier (13) are subsequently joined again.

9. The sorption cycle according to claim 7, characterized in that heat generated by absorbing the medium pressure partial flow is initially emitted to a heat carrier (31) of the heat sink and subsequently heat generated by absorbing the high-pressure partial flow (44) is subsequently emitted to the heat carrier (31) of the heat sink.

10. The sorption cycle according to one of the claims 7 through 9, characterized in that the solvent (53) is divided into the first partial flow (54) and the second partial flow (55).