Cascade heating type heating system

Abstract

The invention belongs to the technical field of heating devices, and particularly relates to a cascade heat removal type heating system. The cascade heat removal type heating system comprises a heat source fluid conveying pipeline, a heat source fluid backflow pipeline, an expansion machine, a liquid flow heat removal branch, a steam heat removal branch and a heating fluid circulation pipeline. The liquid flow heat extraction branch comprises a first generator, a first condenser, a first evaporator, a first absorber, a first working medium circulation structure connected between the first generator and the first absorber and a heat exchanger which are arranged in sequence; the steam heat removal branch comprises a compressor, a second generator, a second condenser, a second evaporator, a second absorber and a second working medium circulation structure connected to the second generator and the second absorber which are sequentially arranged. In the heating process, when only a compressor compresses water vapor in a steam heat extraction branch, when a second evaporator is vacuumized, and when a second working medium circulation structure connected to a second generator and a second absorber works, energy needs to be consumed, and the problem that an existing heat pump unit is high in heating operation cost is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of heating devices, and in particular relates to a step-heating heating system. Background Art

[0002] At present, there are two main sources of heat source fluid for heat pump units. One is production wastewater above 100°C generated in the production of printing and dyeing, metallurgy, chemical industry, petroleum, electric power and other industries; the other is ground source hot water above 100°C. The heat pump unit can use the heat in production wastewater or ground source hot water for heating, which can be used for heating systems, preheating raw materials, and providing domestic hot water. For example, the Chinese utility model patent with the publication number CN206504385U discloses a geothermal heating heat pump unit that can use geothermal energy for heating, and the Chinese invention patent with the publication number CN110145786A discloses a geothermal multi-branch well heat extraction heating system that can provide heating to heat users through the heat pump unit. Since the energy consumption of the heat pump unit is relatively large when it is working, the operating cost is relatively high. Summary of the Invention

[0003] The object of the present invention is to provide a cascade heat extraction heating system, aiming to solve the problem of high operating costs of existing heat pump units for heating.

[0004] The present invention discloses a cascade heat extraction type heating system, which includes a heat source fluid delivery pipeline and a heat source fluid return pipeline, and is characterized in that it also includes an expander connected to the heat source fluid delivery pipeline, a liquid flow heat extraction branch connected to the liquid flow outlet of the expander, a steam heat extraction branch connected to the steam outlet of the expander, and a heating fluid circulation pipeline;

[0005] The liquid heat extraction branch includes a first generator, a first condenser, a first evaporator, and a first absorber arranged in sequence, a first working medium circulation structure connected between the first generator and the first absorber, a first vacuum pump connected to the first evaporator, and a heat exchanger, the heat source fluid inlet of the first generator is connected to the liquid outlet of the expander, the heat source fluid outlet of the first generator is connected to the hot end inlet of the heat exchanger, the steam outlet of the first generator is connected to the steam inlet of the first condenser, the heat source fluid inlet of the first evaporator is connected to the hot end outlet of the heat exchanger, the steam outlet of the first evaporator is connected to the steam inlet of the first absorber, and a first liquid flow communication pipeline is connected between the first evaporator and the first condenser;

[0006] The steam heat extraction branch includes a compressor, a second generator, a second condenser, a second evaporator, and a second absorber arranged in sequence, a second working medium circulation structure connected to the second generator and the second absorber, and a second vacuum pump connected to the second condenser, an air inlet of the compressor is connected to the steam outlet of the expander, an air outlet of the compressor is connected to the heat source fluid inlet of the second generator, the steam outlet of the second generator is connected to the steam inlet of the second condenser, the steam outlet of the second evaporator is connected to the steam inlet of the second absorber, the heat source fluid inlet of the second evaporator is connected to the heat source liquid flow outlet of the first evaporator, the heat source liquid flow outlet of the second evaporator is connected to the heat source fluid reflux pipeline, and a second liquid flow connecting pipeline is connected between the second condenser and the second evaporator;

[0007] The heating fluid circulation pipeline includes a heating medium inlet pipeline connected to the cold end inlet of the heat exchanger and a heating medium outflow pipeline connected to the cold end outlet of the heat exchanger. The heating medium inlet of the first absorber and the heating medium inlet of the second absorber are respectively connected to the heating medium inlet pipeline, the heating medium outlet of the first condenser, the heating medium outlet of the second generator, and the heating medium outlet of the second condenser are respectively connected to the heating medium outflow pipeline, the heating medium outlet of the first absorber is connected to the heating medium inlet of the first condenser, and the heating medium outlet of the second absorber is connected to the heating medium inlet of the second condenser.

[0008] As an improvement, liquid flow regulating valves are respectively connected in series to the first liquid flow communicating pipeline and the second liquid flow communicating pipeline.

[0009] As an improvement, gas flow regulating valves are respectively provided between the steam outlet of the first generator and the steam inlet of the first condenser, between the steam outlet of the first evaporator and the steam inlet of the first absorber, between the steam outlet of the second generator and the steam inlet of the second condenser, and between the steam outlet of the second evaporator and the steam inlet of the second absorber.

[0010] As an improvement, the first working medium circulation structure comprises a first self-flow communication pipe connected between the first generator and the first absorber, an inlet end of the first self-flow communication pipe is connected to the first generator and is arranged below the liquid level of the working medium inside the first generator, and an outlet end of the first self-flow communication pipe is connected to the first absorber and is arranged above the liquid level of the working medium inside the first absorber; and the first working medium circulation structure further comprises a first suction pipe and a first suction pump connected in series to the first suction pipe, an inlet end of the first suction pipe is connected to the first absorber and is arranged below the liquid level of the working medium inside the first absorber, and an outlet end of the first suction pipe is connected to the first generator and is arranged above the liquid level of the working medium inside the first generator.

[0011] As an improvement, the second working medium circulation structure comprises a second self-flow communication pipe connected between the second generator and the second absorber, an inlet end of the second self-flow communication pipe is connected to the second generator and is arranged below the liquid level of the working medium inside the second generator, and an outlet end of the second self-flow communication pipe is connected to the second absorber and is arranged above the liquid level of the working medium inside the second absorber; and the second working medium circulation structure further comprises a second suction pipe and a second suction pump connected in series to the second suction pipe, an inlet end of the second suction pipe is connected to the second absorber and is arranged below the liquid level of the working medium inside the second absorber, and an outlet end of the second suction pipe is connected to the second generator and is arranged above the liquid level of the working medium inside the second generator.

[0012] As an improvement, the heating medium outlet of the first condenser is connected to the first reflux pipe, and the heating medium outlet of the second condenser and the heat source fluid outlet of the second generator are connected to the second reflux pipe.

[0013] As an improvement, one-way valves are connected in series to the first reflux pipe and the second reflux pipe.

[0014] Thanks to the above technical solutions, the following beneficial effects are achieved:

[0015] The step-by-step heat extraction type heating system comprises a heat source fluid conveying pipe and a heat source fluid reflux pipe, an expander connected to the heat source fluid conveying pipe, a liquid flow heat extraction branch connected to the liquid flow outlet of the expander, a steam heat extraction branch connected to the steam outlet of the expander, and a heating fluid circulation pipe.

[0016] The liquid heat extraction branch includes a first generator, a first condenser, a first evaporator, and a first absorber arranged in sequence, a first working medium circulation structure connected between the first generator and the first absorber, a first vacuum pump connected to the first evaporator, and a heat exchanger, the heat source fluid inlet of the first generator is connected to the liquid outlet of the expander, the heat source fluid outlet of the first generator is connected to the hot end inlet of the heat exchanger, the steam outlet of the first generator is connected to the steam inlet of the first condenser, the heat source fluid inlet of the first evaporator is connected to the hot end outlet of the heat exchanger, the steam outlet of the first evaporator is connected to the steam inlet of the first absorber, and a first liquid flow communication pipeline is connected between the first evaporator and the first condenser;

[0017] The steam heat extraction branch includes a compressor, a second generator, a second condenser, a second evaporator, and a second absorber which are arranged in sequence, a second working medium circulation structure connected to the second generator and the second absorber, and a second vacuum pump connected to the second condenser, an air inlet of the compressor is connected to the steam outlet of the expander, an air outlet of the compressor is connected to the heat source fluid inlet of the second generator, the steam outlet of the second generator is connected to the steam inlet of the second condenser, the steam outlet of the second evaporator is connected to the steam inlet of the second absorber, the heat source fluid inlet of the second evaporator is connected to the heat source liquid flow outlet of the first evaporator, the heat source liquid flow outlet of the second evaporator is connected to the heat source fluid reflux pipeline, and a second liquid flow connecting pipeline is connected between the second condenser and the second evaporator;

[0018] The heating fluid circulation pipeline includes a heating medium inlet pipeline connected to the cold end inlet of the heat exchanger and a heating medium outflow pipeline connected to the cold end outlet of the heat exchanger. The heating medium inlet of the first absorber and the heating medium inlet of the second absorber are respectively connected to the heating medium inlet pipeline, the heating medium outlet of the first condenser, the heating medium outlet of the second generator, and the heating medium outlet of the second condenser are respectively connected to the heating medium outflow pipeline, the heating medium outlet of the first absorber is connected to the heating medium inlet of the first condenser, and the heating medium outlet of the second absorber is connected to the heating medium inlet of the second condenser.

[0019] During the heating process, the high-temperature heat source fluid is divided into a liquid heat-taking branch and a steam heat-taking branch. The heating medium flows into the pipeline and divides the heating water to be heated into three paths for heating. Among them, the first path of heating water flows through the heat exchanger and then flows into the heating medium outflow pipeline. The second path of heating water flows through the first absorber and the first condenser and then flows into the heating medium outflow pipeline. The second path of heating water takes heat in the first absorber and the first condenser in sequence to form a step-by-step heating. The third path of heating water flows through the second absorber and the second condenser and then flows into the heating medium outflow pipeline. The third path of heating water flows through the second absorber and the second condenser and then flows into the heating medium outflow pipeline. The heat is taken from the first evaporator and the second condenser in sequence to form a stepped heat taking; in the liquid heat taking branch, only the first evaporator needs to consume energy when it is evacuating and the first working fluid circulation structure connected between the first generator and the first absorber is working; in the steam heat taking branch, only the compressor of the steam heat taking branch needs to consume energy when it compresses water vapor, the second evaporator needs to consume energy when it is evacuating and the second working fluid circulation structure connected to the second generator and the second absorber is working, which can effectively reduce energy consumption, thereby reducing operating costs and solving the problem of high operating costs of existing heat pump units for heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a schematic structural diagram of a cascade heat extraction heating system according to an embodiment of the present invention;

[0021] Among them, 10, heat source fluid delivery pipeline; 20, expander; 31, first generator; 32, first condenser; 33, first evaporator; 34, first absorber; 35, heat exchanger; 41, compressor; 42, second generator; 43, second condenser; 44, second evaporator; 45, second absorber; 50, heat source fluid connecting pipeline; 60, heat source fluid return pipeline; 71, heating medium inflow pipeline; 72, heating medium outflow pipeline; 81, first return pipeline; 82, second return pipeline. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0023] Figure 1 The figure shows a schematic structural diagram of the cascade heat extraction heating system of the present invention. For the convenience of description, only the parts related to the present invention are shown in the figure.

[0024] It should be noted that if the embodiments of the present invention involve directional indications, such as up, down, front, back, left, right, etc., then the directional indications are only used to explain the relative positional relationship between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly; if the embodiments of the present invention involve descriptions of "first", "second", etc., then the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0025] like Figure 1 As shown, an embodiment of the present invention discloses a cascade heat extraction heating system for utilizing waste heat from industrial wastewater (from printing and dyeing, metallurgy, chemical industry, petroleum, electric power, and other industries) and heat in ground source hot water. The system is particularly suitable for industrial wastewater and ground source hot water with a temperature above 100°C. The cascade heat extraction heating system of the embodiment of the present invention includes a heat source fluid delivery pipeline 10 and a heat source fluid return pipeline 60, an expander 20 connected to the heat source fluid delivery pipeline 10, a liquid heat extraction branch connected to the liquid outlet of the expander 20, a steam heat extraction branch connected to the steam outlet of the expander 20, and a heating fluid circulation pipeline.

[0026] The liquid heat extraction branch includes a first generator 31, a first condenser 32, a first evaporator 33, and a first absorber 34, which are arranged in sequence; a first working medium circulation structure connected between the first generator 31 and the first absorber 34; a first vacuum pump connected to the first evaporator 33 for maintaining a negative pressure inside the first evaporator 33; and a heat exchanger 35; the heat source fluid inlet of the first generator 31 is connected to the liquid outlet of the expander 20; the heat source fluid outlet of the first generator 31 is connected to the hot end inlet of the heat exchanger 35; the steam outlet of the first generator 31 is connected to the steam inlet of the first condenser 32; the heat source fluid inlet of the first evaporator 33 is connected to the hot end outlet of the heat exchanger 35; the steam outlet of the first evaporator 33 is connected to the steam inlet of the first absorber 34; and a first liquid flow communication pipeline is connected between the first evaporator 33 and the first condenser 32;

[0027] The steam heat extraction branch includes a compressor 41, a second generator 42, a second condenser 43, a second evaporator 44, and a second absorber 45, which are arranged in sequence. A second working medium circulation structure is connected to the second generator 42 and the second absorber 45, and a second vacuum pump is connected to the second condenser 43 for maintaining a negative pressure state inside the second condenser 43. The air inlet of the compressor 41 is connected to the steam outlet of the expander 20, the air outlet of the compressor 41 is connected to the heat source fluid inlet of the second generator 42, and the steam outlet of the second generator 42 is connected to the second condenser. The steam inlet of the condenser 43 and the steam outlet of the second evaporator 44 are connected to the steam inlet of the second absorber 45, the heat source fluid inlet of the second evaporator 44 is connected to the heat source liquid flow outlet of the first evaporator 33, and the heat source liquid flow outlet of the second evaporator 44 is connected to the heat source fluid return pipeline 60. A second liquid flow connecting pipeline is connected between the second condenser 43 and the second evaporator 44. The water vapor inside the second generator 42 enters the second condenser 43 and condenses to form liquid water. The liquid water flows into the second evaporator 44 through the second liquid flow connecting pipeline;

[0028] The heating fluid circulation pipeline includes a heating medium inlet pipeline 71 connected to the cold end inlet of the heat exchanger 35, and a heating medium outflow pipeline 72 connected to the cold end outlet of the heat exchanger 35. The heating medium inlet of the first absorber 34 and the heating medium inlet of the second absorber 45 are respectively connected to the heating medium inlet pipeline 71, the heating medium outlet of the first condenser 32, the heating medium outlet of the second generator 42, and the heating medium outlet of the second condenser 43 are respectively connected to the heating medium outflow pipeline 72, the heating medium outlet of the first absorber 34 is connected to the heating medium inlet of the first condenser 32, and the heating medium outlet of the second absorber 45 is connected to the heating medium inlet of the second condenser 43.

[0029] For ease of understanding, the following explanation is given using the heat of ground source hot water for heating:

[0030] The working fluid is pre-injected into the first generator 31, the first absorber 34, the second generator 42, and the second absorber 45, and a portion of gas space is formed inside the first generator 31, the first absorber 34, the second generator 42, and the second absorber 45. Common working fluids include lithium bromide solution, ammonia solution, etc., which have strong water absorption and can release heat when absorbing water.

[0031] During operation, 120°C geothermal hot water is transported to the expander 20 through the heat source fluid transport pipeline 10, and a hot water medium and a water vapor medium at about 105°C are formed through the action of the expander 20. When the expander 20 is working, the geothermal hot water is reduced to a temperature above 100°C to facilitate the formation of water vapor. Among them, the hot water medium is transported to the liquid flow heat extraction branch and the water vapor medium is transported to the steam heat extraction branch. Specifically, the structure and working principle of the expander 20 are well-known technologies, and its specific structure will not be repeated here.

[0032] The heating medium inlet pipeline 71 is used to transport heating water that needs to be heated, and is divided into three paths for heating. Among them, the first path of heating water flows through the heat exchanger 35 and then flows into the heating medium outflow pipeline 72, the second path of heating water flows through the first absorber 34 and the first condenser 32 and then flows into the heating medium outflow pipeline 72, and the third path of heating water flows through the second absorber 45 and the second condenser 43 and then flows into the heating medium outflow pipeline 72.

[0033] For the liquid heat extraction branch:

[0034] The hot water medium at about 105°C enters the internal pipeline of the first generator 31 from the heat source fluid inlet of the first generator 31. Since the internal pipeline of the first generator 31 is immersed in the working medium, it can heat the working medium inside the first generator 31, and the water in the working medium evaporates to form high-temperature water vapor at about 90°C. Part of the heat in the hot water medium is transferred to the inside of the high-temperature water vapor, and the pressure inside the first generator 31 increases. The high-temperature water vapor inside the first generator 31 enters the first condenser 32 from the steam outlet of the first generator 31 and the steam inlet of the first condenser 32. After the high-temperature water vapor is condensed in the first condenser 32, it forms liquid water with a temperature of about 40°C. At the same time, since the inside of the first evaporator 33 is in a negative pressure state, the liquid water can automatically flow into the first evaporator 33 through the first liquid flow connecting pipeline;

[0035] The temperature of the hot water medium flowing out of the heat source fluid outlet of the first generator 31 is reduced to about 95°C, and the hot water medium flowing out of the heat source fluid outlet of the first generator 31 flows into the inside of the heat exchanger 35 through the hot end inlet of the heat exchanger 35, so as to heat the first route heating water flowing through the heat exchanger 35. The temperature of the hot water medium flowing out of the hot end outlet of the heat exchanger 35 is reduced to about 50°C, and the hot water medium flowing out of the hot end outlet of the heat exchanger 35 flows into the inside pipe of the first evaporator 33 through the heat source fluid inlet of the first evaporator 33, so as to heat the liquid water flowing into the inside of the first evaporator 33 from the first condenser 32. Since the inside of the first evaporator 33 is in a negative pressure state, the boiling point of water is reduced in the negative pressure environment, so as to gasify the liquid water flowing into the inside of the first evaporator 33 to form low-temperature water vapor of about 45°C. Since the working medium in the first absorber 34 has strong water absorption, the water vapor in the inside of the first evaporator 33 enters the inside of the first absorber 34 through the steam outlet of the first evaporator 33 and the steam inlet of the first absorber 34 under the water absorption of the working medium in the first absorber 34. The water vapor entering the inside of the first absorber 34 is absorbed by the working medium in the first absorber 34 and releases heat, so that the concentration of the working medium is reduced and the temperature is increased.

[0036] The hot water medium flowing out of the heat source medium outlet of the first evaporator 33 flows into the inside pipe of the second evaporator 44 through the heat source medium inlet of the second evaporator 44, and then flows back to the heat source fluid return pipe 60 through the heat source medium outlet of the second evaporator 44.

[0037] Among them, the first route heating water flows into the cold end inlet of the heat exchanger 35 through the heating medium inflow pipe 71, and the hot water medium flowing out of the heat source fluid outlet of the first generator 31 flows into the inside of the heat exchanger 35 through the hot end inlet of the heat exchanger 35 to heat the first route heating water flowing through the heat exchanger 35.

[0038] The second heating water flows from the heating medium inflow pipe 71 into the first absorber 34. When the second heating water flows through the internal pipe of the first absorber 34, due to the strong water absorption of the working medium in the first absorber 34, the water vapor in the first evaporator 33 enters the first absorber 34 through the steam outlet of the first evaporator 33 and the steam inlet of the first absorber 34. The water vapor entering the first absorber 34 is absorbed by the working medium in the first absorber 34 and releases heat. The working medium concentration decreases and the temperature increases, thereby performing primary heating on the second heating water flowing through the internal pipe of the first absorber 34 and heating the second heating water to about 60°C. The second heating water that has undergone primary heating flows out from the heating medium outlet of the first absorber 34 and enters the internal pipeline of the first condenser 32 through the heating medium inlet of the first condenser 32. The high-temperature steam that enters the first condenser 32 from the steam outlet of the first generator 31 and the steam inlet of the first condenser 32 performs secondary heating on the second heating water flowing through the internal pipeline of the first condenser 32, heating the second heating water to about 80°C. After the secondary heating, the second heating water flows out from the heating medium outlet of the first condenser 32 and flows into the heating medium outflow pipeline 72. The second heating water takes heat in the first absorber 34 and the first condenser 32 in sequence to form a step-by-step heating, which can enhance the efficiency of thermal energy utilization.

[0039] For the steam heat extraction branch:

[0040] The water vapor medium at about 105°C enters the compressor 41. After being compressed by the compressor 41, the pressure of the water vapor medium increases and can be smoothly transported to the second generator 42. The water vapor medium enters the internal pipeline of the second generator 42 from the heat source fluid inlet of the second generator 42. Since the internal pipeline of the second generator 42 is immersed in the working medium, the water vapor medium flowing through the internal pipeline of the second generator 42 can heat the working medium. The water vapor medium condenses after heat exchange in the second generator 42 to form medium hot water at about 80°C. The medium hot water flowing out of the heat source fluid outlet of the second generator 42 flows into the heating medium outflow pipeline 72 and is used as heating water. Since the medium hot water is formed by condensation of the water vapor medium, it is very pure and will not have an adverse effect on the circulation, pipelines, and user-end pipelines of the heating water.

[0041] The water vapor medium flowing through the internal pipeline of the second generator 42 can heat the working medium. The water in the working medium evaporates to form high-temperature water vapor at about 90°C. A portion of the heat in the water vapor medium is transferred to the interior of the high-temperature water vapor. The pressure inside the second generator 42 increases. The high-temperature water vapor inside the second generator 42 enters the interior of the second condenser 43 through the steam outlet of the second generator 42 and the steam inlet of the second condenser 43. The high-temperature water vapor condenses inside the second condenser 43 to form liquid water. The temperature of the liquid water is about 40°C.

[0042] Since the interior of the second evaporator 44 is in a negative pressure state, the high-temperature water vapor entering the second condenser 43 from the second generator 42 condenses inside the second condenser 43 to form liquid water that can automatically flow into the interior of the second evaporator 44 through the second liquid flow connecting pipe;

[0043] The hot water medium flowing into the internal pipeline of the second evaporator 44 from the heat source fluid outlet of the first evaporator 33 via the heat source fluid inlet of the second evaporator 44 can heat the liquid water flowing into the second evaporator 44 from the second condenser 43. Since the interior of the second evaporator 44 is in a negative pressure state, the boiling point of water is reduced under the negative pressure environment, and the liquid water flowing into the second evaporator 44 can be vaporized to form low-temperature water vapor of about 45°C; since the working fluid inside the second absorber 45 has strong water absorption, under the water absorption effect of the working fluid inside the second absorber 45, the low-temperature water vapor inside the second evaporator 44 enters the second absorber 45 through the steam outlet of the second evaporator 44 and the steam inlet of the second absorber 45. The water vapor entering the second absorber 45 is absorbed by the working fluid inside the second absorber 45 and releases heat, and the working fluid concentration decreases while the temperature increases.

[0044] The third heating water flows into the second absorber 45 from the heating medium inflow pipeline 71. When the third heating water flows through the internal pipeline of the second absorber 45, the water vapor in the second evaporator 44 enters the internal pipeline of the second absorber 45 through the steam outlet of the second evaporator 44 and the steam inlet of the second absorber 45 due to the strong water absorption of the working medium in the second absorber 45, and the water vapor in the internal pipeline of the second absorber 45 is absorbed by the working medium in the internal pipeline of the second absorber 45 to release heat, so that the concentration of the working medium is reduced and the temperature is increased, thereby the third heating water flowing through the internal pipeline of the second absorber 45 is heated to about 60 DEG C by the primary heating of the second absorber 45; the third heating water after the primary heating flows out of the heating medium outlet of the second absorber 45 and enters the internal pipeline of the second condenser 43 through the heating medium inlet of the second condenser 43, and the high-temperature steam in the internal pipeline of the second condenser 43 enters the internal pipeline of the second condenser 43 through the steam outlet of the second generator 42 and the steam inlet of the second condenser 43, so that the third heating water flowing through the internal pipeline of the second condenser 43 is heated to about 80 DEG C by the secondary heating of the second condenser 43, and the third heating water after the secondary heating flows out of the heating medium outlet of the second condenser 43 and flows into the heating medium outflow pipeline 72, so that the third heating water is sequentially heated in the second absorber 45 and the second condenser 43 to form a gradient heating, thereby the heat energy utilization efficiency is improved.

[0045] In the heating process, the high-temperature heat source fluid is divided into a liquid flow heat extraction branch and a steam heat extraction branch, and the heating medium inflow pipeline 71 divides the heating water to be heated into three parts for heating, wherein the first heating water flows through the heat exchanger 35 and then flows into the heating medium outflow pipeline 72, the second heating water flows through the first absorber 34 and the first condenser 32 and then flows into the heating medium outflow pipeline 72, the second heating water is sequentially heated in the first absorber 34 and the first condenser 32 to form a gradient heating, and the third heating water flows through the second absorber 45 and the second condenser 43 and then flows into the heating medium outflow pipeline 72, the third heating water is sequentially heated in the second absorber 45 and the second condenser 43 to form a gradient heating; in the whole heating process, only the first evaporator 33 in the liquid flow heat extraction branch needs to consume energy when being vacuumized, only the compressor 41 in the steam heat extraction branch needs to consume energy when compressing water vapor, only the second evaporator 44 in the steam heat extraction branch needs to consume energy when being vacuumized, and only the second working medium circulation structure connected between the second generator 42 and the second absorber 45 needs to consume energy when working, thereby the energy consumption is effectively reduced, the operation cost is reduced, and the problem of high operation cost of the existing heat pump unit heating is solved.

[0046] Specifically, the structure and working principle of the first generator 31, the first condenser 32, the first evaporator 33, the first absorber 34, the first vacuum pump, the heat exchanger 35, the compressor 41, the second generator 42, the second condenser 43, the second evaporator 44, the second absorber 45, and the second vacuum pump are known technologies, and the specific structure will not be described here.

[0047] In the embodiment of the present application, in order to maintain the negative pressure state inside the first evaporator 33 and the second evaporator 44, and to avoid that all the condensed water inside the first condenser 32 flows into the first evaporator 33 and all the condensed water inside the second condenser 43 flows into the second evaporator 44, liquid flow regulating valves are respectively connected in series on the first liquid flow communication pipeline and the second liquid flow communication pipeline.

[0048] Specifically, the liquid flow regulating valve can be a manual regulating valve or an electric regulating valve.

[0049] In the embodiment of the present application, the first working medium circulation structure includes a first self-flow communication pipe connected between the first generator 31 and the first absorber 34, the inlet end of the first self-flow communication pipe is connected to the first generator 31 and is arranged below the liquid level of the working medium inside the first generator 31, and the outlet end of the first self-flow communication pipe is connected to the first absorber 34 and is arranged above the liquid level of the working medium inside the first absorber 34; the first working medium circulation structure also includes a first suction pipe and a first suction pump connected in series to the first suction pipe, the inlet end of the first suction pipe is connected to the first absorber 34 and is arranged below the liquid level of the working medium inside the first absorber 34, and the outlet end of the first suction pipe is connected to the first generator 31 and is arranged above the liquid level of the working medium inside the first generator 31.

[0050] The second working medium circulation structure includes a second self-flow communication pipe connected between the second generator 42 and the second absorber 45, the inlet end of the second self-flow communication pipe is connected to the second generator 42 and is arranged below the liquid level of the working medium inside the second generator 42, and the outlet end of the second self-flow communication pipe is connected to the second absorber 45 and is arranged above the liquid level of the working medium inside the second absorber 45; the second working medium circulation structure also includes a second suction pipe and a second suction pump connected in series to the second suction pipe, the inlet end of the second suction pipe is connected to the second absorber 45 and is arranged below the liquid level of the working medium inside the second absorber 45, and the outlet end of the second suction pipe is connected to the second generator 42 and is arranged above the liquid level of the working medium inside the second generator 42.

[0051] In other embodiments, the first working medium circulation structure and the second working medium circulation structure can also be provided in the following structure forms, wherein the first suction pump and the second suction pump can also be provided in the form of a submersible pump.

[0052] In an embodiment of the present invention, gas flow regulating valves are respectively provided between the steam outlet of the first generator 31 and the steam inlet of the first condenser 32, between the steam outlet of the first evaporator 33 and the steam inlet of the first absorber 34, between the steam outlet of the second generator 42 and the steam inlet of the second condenser 43, and between the steam outlet of the second evaporator 44 and the steam inlet of the second absorber 45, for regulating the flow rate of steam.

[0053] Specifically, the gas flow regulating valve can be configured as a manual regulating valve or an electric regulating valve.

[0054] In an embodiment of the present invention, a first return pipeline 81 and a second return pipeline 82 are respectively connected to the heating medium outflow pipeline 72, the heating medium outlet of the first condenser 32 is connected to the first return pipeline 81, and the heating medium outlet of the second condenser 43 and the heat source fluid outlet of the second generator 42 are respectively connected to the second return pipeline 82.

[0055] Specifically, one-way valves are connected in series to the first return line 81 and the second return line 82 respectively to prevent backflow between the heating medium outflow line 72 and the first condenser 32 , the second condenser 43 and the second generator 42 .

[0056] The above descriptions are merely some embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cascade heat extraction heating system, comprising a heat source fluid delivery pipeline and a heat source fluid return pipeline, characterized in that: It also includes an expander connected to the heat source fluid delivery pipeline, a liquid heat extraction branch connected to the liquid outlet of the expander, a steam heat extraction branch connected to the steam outlet of the expander, and a heating fluid circulation pipeline; The liquid heat extraction branch includes a first generator, a first condenser, a first evaporator, and a first absorber arranged in sequence, a first working medium circulation structure connected between the first generator and the first absorber, a first vacuum pump connected to the first evaporator, and a heat exchanger, the heat source fluid inlet of the first generator is connected to the liquid outlet of the expander, the heat source fluid outlet of the first generator is connected to the hot end inlet of the heat exchanger, the steam outlet of the first generator is connected to the steam inlet of the first condenser, the heat source fluid inlet of the first evaporator is connected to the hot end outlet of the heat exchanger, the steam outlet of the first evaporator is connected to the steam inlet of the first absorber, and a first liquid flow communication pipeline is connected between the first evaporator and the first condenser; The steam heat extraction branch includes a compressor, a second generator, a second condenser, a second evaporator, and a second absorber arranged in sequence, a second working medium circulation structure connected to the second generator and the second absorber, and a second vacuum pump connected to the second condenser, an air inlet of the compressor is connected to the steam outlet of the expander, an air outlet of the compressor is connected to the heat source fluid inlet of the second generator, the steam outlet of the second generator is connected to the steam inlet of the second condenser, the steam outlet of the second evaporator is connected to the steam inlet of the second absorber, the heat source fluid inlet of the second evaporator is connected to the heat source liquid flow outlet of the first evaporator, the heat source liquid flow outlet of the second evaporator is connected to the heat source fluid reflux pipeline, and a second liquid flow connecting pipeline is connected between the second condenser and the second evaporator; The heating fluid circulation pipeline includes a heating medium inlet pipeline connected to the cold end inlet of the heat exchanger and a heating medium outflow pipeline connected to the cold end outlet of the heat exchanger. The heating medium inlet of the first absorber and the heating medium inlet of the second absorber are respectively connected to the heating medium inlet pipeline, the heating medium outlet of the first condenser, the heating medium outlet of the second generator, and the heating medium outlet of the second condenser are respectively connected to the heating medium outflow pipeline, the heating medium outlet of the first absorber is connected to the heating medium inlet of the first condenser, and the heating medium outlet of the second absorber is connected to the heating medium inlet of the second condenser.

2. The cascade heat extraction heating system according to claim 1, characterized in that: Liquid flow regulating valves are respectively connected in series to the first liquid flow communicating pipeline and the second liquid flow communicating pipeline.

3. The cascade heat extraction heating system according to claim 1, characterized in that: Gas flow regulating valves are respectively provided between the steam outlet of the first generator and the steam inlet of the first condenser, between the steam outlet of the first evaporator and the steam inlet of the first absorber, between the steam outlet of the second generator and the steam inlet of the second condenser, and between the steam outlet of the second evaporator and the steam inlet of the second absorber.

4. The cascade heat extraction heating system according to claim 1, characterized in that: The first working fluid circulation structure includes a first gravity-flow connecting pipe connected between the first generator and the first absorber, the inlet end of the first gravity-flow connecting pipe is connected to the first generator and is arranged below the liquid level of the working fluid inside the first generator, and the outlet end of the first gravity-flow connecting pipe is connected to the first absorber and is arranged above the liquid level of the working fluid inside the first absorber; it also includes a first suction pipe and a first suction pump connected in series with the first suction pipe, the inlet end of the first suction pipe is connected to the first absorber and is arranged below the liquid level of the working fluid inside the first absorber, and the outlet end of the first suction pipe is connected to the first generator and is arranged above the liquid level of the working fluid inside the first generator.

5. The cascade heat extraction heating system according to claim 1, characterized in that: The second working medium circulation structure includes a second self-flowing connecting pipe connected between the second generator and the second absorber, the inlet end of the second self-flowing connecting pipe is connected to the second generator and is arranged below the liquid level of the working medium inside the second generator, and the outlet end of the second self-flowing connecting pipe is connected to the second absorber and is arranged above the liquid level of the working medium inside the second absorber; it also includes a second suction pipe and a second suction pump connected in series with the second suction pipe, the inlet end of the second suction pipe is connected to the second absorber and is arranged below the liquid level of the working medium inside the second absorber, and the outlet end of the second suction pipe is connected to the second generator and is arranged above the liquid level of the working medium inside the second generator.

6. The cascade heat extraction heating system according to any one of claims 1 to 5, characterized in that: The first return pipeline and the second return pipeline are respectively connected to the heating medium outflow pipeline, the heating medium outlet of the first condenser is connected to the first return pipeline, and the heating medium outlet of the second condenser and the heat source fluid outlet of the second generator are respectively connected to the second return pipeline.

7. The cascade heat extraction heating system according to claim 6, characterized in that: One-way valves are respectively connected in series to the first return pipeline and the second return pipeline.

Images