Combined heat pump heat supply system and method for deep waste heat utilization of thermoelectric unit

Abstract

The invention relates to the technical field of clean heat supply, in particular to a combined heat pump heat supply system and method for deep waste heat utilization of a thermoelectric unit, deep recovery of tail flue gas waste heat is achieved through combination of an absorption heat pump unit and a compression heat pump unit, the tail flue gas waste heat participates in heat supply, the water supplementing amount and the heat supply cost are reduced, and meanwhile the heat supply efficiency is improved. The low-temperature organic Rankine power cycle unit is driven by heat supply network drain water with medium-temperature-grade heat energy to provide power for the system, dual utilization of energy grade and quantity is achieved, and the energy utilization efficiency of the system is improved in an energy gradient utilization mode. Besides, condensed water generated by flue gas cooling in the spraying tower is high in quality, the problems of blockage, corrosion and the like of a heat exchanger are avoided when the condensed water serves as an intermediate conveying medium of low-temperature heat sources of the absorption heat pump unit and the compression heat pump unit, the system operation and maintenance cost is reduced, and the operation economic benefits of the cogeneration unit are further improved. The problem that in the prior art, the waste heat recycling rate of a cogeneration unit is low is solved.

Description

Technical Field

[0001] The present invention relates to the field of clean heating technology, and in particular to a combined heat pump heating system and method for deep waste heat utilization of thermal power units. Background Art

[0002] In recent years, new renewable energy power systems based on wind and light have been vigorously developed. The new energy power system is a clean, low-carbon, efficient, safe, and sustainable power system. It emphasizes the widespread application of new energy, smart grid and energy storage technology to achieve the replacement of traditional thermal power generation and nuclear power generation. However, due to the natural fluctuation characteristics of new energy such as wind power and photovoltaic power generation, their large-scale development and utilization will further highlight the contradiction between electricity supply and demand. Therefore, as a traditional power generation method, thermal power units still play an important role in the new energy power system with their stable output characteristics and flexible adjustment capabilities. As a key technology in the field of energy conservation, the utilization of waste heat from thermal power units is one of the important directions in technological transformation. As the basic power source in the new energy and power system structure, thermal power units play important roles in peak load regulation, frequency regulation and supply guarantee. In the northern region, thermal power units mostly exist in the form of cogeneration. In areas with high heating demand, the application field of waste heat recovery is relatively large. The unit's heating steam extraction and flue gas waste heat exists in the form of medium and low temperature waste heat. Efficient use of these two types of waste heat is of great significance both to the unit's energy efficiency level and to promoting energy transformation.

[0003] In conventional cogeneration units, the heat network drain has a temperature of about 130°C, a large flow rate, and contains a large amount of waste heat that can be utilized. The conventional method is to heat the condensate through a drain cooler and send it back to the unit in the form of simple heat exchange. Although the heat is recovered, the thermal energy grade is not used in a targeted manner. If the waste heat at this temperature level is used as the driving heat source, the waste heat from other systems in the plant can be additionally recovered to increase the amount of recovered waste heat. While utilizing the heat, the thermal energy grade is also utilized to achieve the purpose of efficient recovery. The exhaust gas at the tail of the unit is usually saturated after passing through the desulfurization tower, carrying a large amount of water vapor, in which the waste heat contained in the latent heat is rich, and the temperature of the tail flue gas is still relatively high, about 60℃~90℃. The existing thermal power units directly discharge these high-temperature flue gases, resulting in a large amount of low-grade thermal energy waste. If the temperature of this part of the flue gas can be lowered, most of the condensate can be recovered while recovering the low-temperature waste heat, and used for heating and water replenishment of systems such as the heat network, realizing the deep waste heat utilization of the thermal cycle, which is of great significance for improving the energy efficiency of thermal power units, reducing energy consumption and reducing emissions. Summary of the invention

[0004] In view of the problem of low waste heat recovery rate in cogeneration units in the prior art, the present invention provides a combined heat pump heating system and method for deep waste heat utilization of cogeneration units.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a combined heat pump heating system for deep waste heat utilization of thermal power units, which at least includes a low-temperature organic Rankine power cycle unit, a compression heat pump unit, an absorption heat pump unit and a flue gas waste heat deep recovery unit; The organic Rankine power cycle unit comprises a waste heat evaporator, a turbine and an organic working fluid condenser connected to the working fluid outlet of the waste heat evaporator in sequence, and the working fluid outlet of the organic working fluid condenser is connected to the working fluid inlet of the waste heat evaporator; The compression heat pump unit comprises a first evaporator, a compressor and a first condenser which are sequentially connected to the working fluid outlet of the first evaporator, and the working fluid outlet of the first condenser is connected to the working fluid inlet of the first evaporator; The absorption heat pump unit comprises a generator and a solution heat exchanger and an absorber connected to the concentrated solution outlet of the generator in sequence, the dilute solution outlet of the absorber is connected to the cold end of the solution heat exchanger and the solution inlet of the generator in sequence; the water vapor outlet of the generator is connected to the second condenser and the second evaporator in sequence, and the water vapor outlet of the second evaporator is connected to the absorber; The flue gas waste heat deep recovery unit comprises a desulfurization tower and a flue gas spray tower connected to the flue gas outlet of the desulfurization tower; the condensate outlet of the flue gas spray tower is divided into two routes, one of which is connected to the first evaporator and the other is connected to the second evaporator; the condensate outlets of the first evaporator and the second evaporator are combined into a mother pipe and divided into two routes, one of which is connected to the organic working fluid condenser and then connected to the flue gas spray tower, and the other is directly connected to the flue gas spray tower; The return water output end of the heat network circulating water is divided into two paths, one of which is connected to the absorber and the second condenser in sequence, the second condenser is connected to the heat network heater, and the water outlet of the heat network heater is connected to the heat network circulating water input end; the other path is connected to the first condenser and the heat network heater in sequence; The heating extraction steam output end is connected to the shell side of the heating network heater, and the condensing heat network water discharge on the shell side of the heating network heater is divided into two paths, one of which is connected to the waste heat evaporator and the other is connected to the generator; the waste heat evaporator and the generator are both connected to the condenser of the unit.

[0006] Optionally, the compressor is arranged coaxially with the turbine.

[0007] Optionally, a first expansion valve is provided between the first evaporator and the first condenser.

[0008] Optionally, the slurry outlet of the desulfurization tower is connected to a desulfurization slurry circulation pump, and the output end of the desulfurization slurry circulation pump is connected to the upper spray end of the desulfurization tower.

[0009] Optionally, a solution pump is provided between the cold end outlet of the solution heat exchanger and the generator, and the solution pump is coaxially arranged with the turbine.

[0010] Optionally, a second expansion valve is provided between the hot end of the solution heat exchanger and the generator; and a third expansion valve is provided between the second condenser and the second evaporator.

[0011] Optionally, a first electric regulating valve is provided between the waste heat evaporator and the condenser; and a second electric regulating valve is provided between the generator and the condenser.

[0012] Optionally, the condensate output end of the flue gas spray tower is connected to a desulfurization tower, and a condensate discharge valve is provided between the condensate output end of the flue gas spray tower and the desulfurization tower.

[0013] Optionally, an organic working fluid pump is provided between the waste heat evaporator and the organic working fluid condenser; and a heating network circulating water pump is provided at the return water output end of the heating network circulating water.

[0014] The present invention also provides a heating method using the combined heat pump heating system for deep waste heat utilization of thermal power units, comprising: The exhaust gas from the exhaust fan outlet is desulfurized and cooled in the desulfurization tower to become saturated exhaust gas, and then introduced into the exhaust gas spray tower for cooling, so that the cooled exhaust gas is discharged and the condensed water generated after cooling falls into the bottom of the spray tower; The condensed water at the bottom of the spray tower is divided into two paths, one of which is transported to the first evaporator to extract the waste heat, and the other is transported to the second evaporator to extract the waste heat; The condensed water at the outlets of the first evaporator and the second evaporator is collected into a main pipe, and then divided into two paths, one of which is transported to the flue gas spray tower, and the other is transported to the working medium condenser, and the condensed water at the outlets of the flue gas spray tower and the working medium condenser is collected into the main pipe and continuously circulated and transported to the first evaporator and the second evaporator; The circulating water return of the heat network is divided into two paths, one of which is transported to the first condenser and then heated by the heat network heater and then transported to the circulating water supply of the heat network, and the other is transported to the absorber and heated by the second condenser and the heat network heater and then transported to the circulating water supply of the heat network; After the working fluid inside the first evaporator absorbs the low-grade waste heat of the condensed water, it is transported to the first condenser to release heat and heat the return water of the heat network, and then the condensed working fluid at the outlet of the first condenser returns to the first evaporator; The working fluid in the waste heat evaporator enters the turbine to do work and drives the compressor to operate, and the exhaust steam working fluid at the turbine outlet is condensed in the working fluid condenser and then sent back to the waste heat evaporator; The concentrated solution in the generator is transported to the hot end of the solution heat exchanger, and then transported to the absorber to release heat and heat the return water of the heat network, so that the formed dilute solution is returned to the generator after being heated by the solution heat exchanger; the water vapor at the generator outlet is transported to the second condenser to heat the return water of the heat network again, and then transported to the second evaporator to evaporate into water vapor and enter the absorber to mix with the concentrated solution; The heating extraction steam enters the shell side of the heating network heater to heat the heating network circulating water, and the condensed heating network drain water is respectively sent to the waste heat evaporator and the generator to provide a driving heat source to complete the heating. Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a combined heat pump heating system for deep waste heat utilization of thermal power units, which at least comprises a low-temperature organic Rankine power cycle unit, a compression heat pump unit, an absorption heat pump unit and a flue gas waste heat deep recovery unit; wherein, the low-temperature organic Rankine power cycle unit drives the compressor to operate by using the power cycle turbine to do work, thereby realizing the direct generation and output utilization of mechanical work; the flue gas waste heat deep recovery unit causes the saturated flue gas at the outlet after the flue gas is sprayed by a desulfurization tower to further recover the flue gas waste heat and condensate through a flue gas spray tower, and utilizes the condensate recovered by the spray tower as desulfurization tower replenishment water; the circulating water after the flue gas waste heat is recovered by the spray tower is indirectly heated as a low-temperature heat source in the evaporators in the absorption heat pump unit and the compression heat pump unit, so that the circulating water return water of the heat network is initially heated by the absorption heat pump unit and the compression heat pump unit, and then heated to the water supply temperature by the heat network heater, and then supplied to the heat users. The heating system realizes deep recovery of tail flue gas waste heat through the combination of absorption heat pump unit and compression heat pump unit, and makes it participate in heating, reducing the amount of water replenishment and heating cost. At the same time, the low-temperature organic Rankine power cycle unit driven by the heat network drainage with medium-temperature grade thermal energy is used to provide power for the system, realizing the dual utilization of energy grade and quantity, and improving the energy utilization efficiency of the system in the form of energy cascade utilization. In addition, the condensate produced by flue gas cooling in the spray tower is of high quality. When it is used as the intermediate transmission medium of the low-temperature heat source of the absorption heat pump unit and the compression heat pump unit, it avoids problems such as heat exchanger blockage and corrosion, reduces the system operation and maintenance costs, and further improves the economic benefits of the cogeneration unit.

[0015] The present invention also provides a heating method using the above-mentioned combined heat pump heating system for deep waste heat utilization of thermal power units. The method desulfurizes and cools the flue gas at the outlet of the induced draft fan through a desulfurization tower to become saturated flue gas, and introduces it into a flue gas spray tower for cooling, so that the cooled flue gas is discharged, and the condensed water generated after cooling is transported to the compression heat pump unit and the absorption heat pump unit respectively as a low-temperature heat source to the heating end; the organic Rankine cycle unit is driven by using the heat network drainage of medium-temperature grade thermal energy as a power source to provide power for the system, thereby realizing efficient coupling of the compression heat pump unit, the absorption heat pump unit, the deep recovery unit of flue gas waste heat and the low-temperature organic Rankine power cycle unit, realizing the dual utilization of energy grade and quantity, and improving the energy utilization efficiency of the system in a cascaded energy utilization manner, thereby realizing a clean, efficient, energy-saving and low-carbon heating method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a combined heat pump heating system for deep waste heat utilization of a thermal power unit according to the present invention.

[0017] Figure 2 The present invention is a flow chart of a combined heat pump heating method for deep waste heat utilization of a thermal power unit.

[0018] Among them, 1-desulfurization tower; 2-desulfurization slurry circulation pump; 3-flue gas spray tower; 4-condensate discharge valve; 5-first evaporator; 6-compressor; 7-first condenser; 8-first expansion valve; 9-organic working fluid pump; 10-waste heat evaporator; 11-turbine; 12-organic working fluid condenser; 13-fifth electric regulating valve; 14-eighth electric regulating valve; 15-generator; 16-second expansion valve; 17-solution heat exchanger; 18-absorber; 19-solution pump; 20-second condenser; 21-third expansion valve; 22-second evaporator; 23-condensate circulation pump; 24-sixth electric regulating valve; 25-seventh electric regulating valve; 26-heating network heater; 27-first electric regulating valve; 28-second electric regulating valve; 29-heating network circulating water pump; 30-third electric regulating valve; 31-fourth electric regulating valve. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0023] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0026] Example 1 See also Figure 1 , the present invention discloses a combined heat pump heating system for deep waste heat utilization of thermal power units, comprising at least a low-temperature organic Rankine power cycle unit, a compression heat pump unit, an absorption heat pump unit and a flue gas waste heat deep recovery unit; The organic Rankine power cycle unit comprises a waste heat evaporator 10, a turbine 11 and an organic working fluid condenser 12 which are sequentially connected to the working fluid outlet of the waste heat evaporator 10, and the working fluid outlet of the organic working fluid condenser 12 is connected to the working fluid inlet of the waste heat evaporator 10; The compression heat pump unit comprises a first evaporator 5, a compressor 6 and a first condenser 7 which are sequentially connected to the working medium outlet of the first evaporator 5, the working medium outlet of the first condenser 7 is connected to the working medium inlet of the first evaporator 5; a first expansion valve 8 is arranged between the first evaporator 5 and the first condenser 7; The absorption heat pump unit comprises a generator 15 and a solution heat exchanger 17 and an absorber 18 which are sequentially connected to the concentrated solution outlet of the generator 15, the dilute solution outlet of the absorber 18 is sequentially connected to the cold end of the solution heat exchanger 17 and the solution inlet of the generator 15, a solution pump 19 is arranged between the cold end outlet of the solution heat exchanger 17 and the generator 15, and the solution pump 19 and the compressor 6 are both coaxially arranged with the turbine 11; the water vapor outlet of the generator 15 is sequentially connected to the second condenser 20 and the second evaporator 22, and the water vapor outlet of the second evaporator 22 is connected to the absorber 18; The flue gas waste heat deep recovery unit includes a desulfurization tower 1 and a flue gas spray tower 3 connected to the flue gas outlet of the desulfurization tower 1; the slurry outlet of the desulfurization tower 1 is connected to a desulfurization slurry circulation pump 2, and the output end of the desulfurization slurry circulation pump 2 is connected to the upper spray end of the desulfurization tower 1; the condensate output end of the flue gas spray tower 3 is connected to the desulfurization tower 1, and a condensate discharge valve 4 is provided between the condensate output end of the flue gas spray tower 3 and the desulfurization tower 1; the condensate outlet of the flue gas spray tower 3 is divided into two routes, one of which is connected to the first evaporator 5, and the other is connected to the second evaporator 22; the condensate outlets of the first evaporator 5 and the second evaporator 22 are combined into a mother pipe and divided into two routes, one of which is connected to the organic working fluid condenser 12 and then connected to the flue gas spray tower 3, and the other is directly connected to the flue gas spray tower 3; The return water output end of the heat network circulating water is divided into two paths, one of which is connected to the absorber 18 and the second condenser 20 in sequence, the second condenser 20 is connected to the heat network heater 26, and the water outlet of the heat network heater 26 is connected to the heat network circulating water input end; the other path is connected to the first condenser 7 and the heat network heater 26 in sequence; The heating extraction steam output end is connected to the shell side of the heat network heater 26, and the shell side condensation heat network of the heat network heater 26 is divided into two paths, one of which is connected to the waste heat evaporator 10 and the other is connected to the generator 15; the waste heat evaporator 10 and the generator 15 are both connected to the condenser of the unit.

[0027] The present invention realizes deep recovery of tail flue gas waste heat through the combination of absorption heat pump unit and compression heat pump unit, and makes it participate in heating, thereby reducing the amount of water replenishment and heating cost. At the same time, the low-temperature organic Rankine power cycle unit driven by the heat network hydrophobicity with medium-temperature grade thermal energy is used to provide power for the system, thereby realizing the dual utilization of energy grade and quantity, and improving the energy utilization efficiency of the system in a cascade utilization of energy; in addition, the condensate water produced by cooling the flue gas in the spray tower is of high quality, and when it is used as the intermediate transmission medium of the low-temperature heat source of the absorption heat pump unit and the compression heat pump unit, it avoids problems such as heat exchanger blockage and corrosion, reduces the system operation and maintenance costs, and further improves the economic benefits of the cogeneration unit operation.

[0028] Example 2 See also Figure 1 , the present invention discloses a combined heat pump heating system for deep waste heat utilization of thermal power units, comprising at least a low-temperature organic Rankine power cycle unit, a compression heat pump unit, an absorption heat pump unit and a flue gas waste heat deep recovery unit; The low-temperature organic Rankine power cycle unit comprises an organic working fluid pump 9, a waste heat evaporator 10, a turbine 11 and an organic working fluid condenser 12; the organic working fluid with a lower boiling point and saturation temperature flows in the internal loop of the low-temperature organic Rankine power cycle unit; The compression heat pump unit comprises a first evaporator 5, a compressor 6, a first condenser 7 and a first expansion valve 8; organic compounds flow in the internal loop of the compression heat pump unit; The absorption heat pump unit comprises a generator 15, a second expansion valve 16, a solution heat exchanger 17, an absorber 18, a solution pump 19, a second condenser 20, a third expansion valve 21 and a second evaporator 22; lithium bromide solution or other compound working fluid flows in the internal loop of the absorption heat pump unit; The flue gas waste heat deep recovery unit comprises a desulfurization tower 1, a desulfurization slurry circulation pump 2, a spray tower 3 and a condensate discharge valve 4; It also includes a heating network heater 26, a first electric regulating valve 27, a second electric regulating valve 28, a heating network circulating water pump 29, a third electric regulating valve 30, a fourth electric regulating valve 31, a fifth electric regulating valve 13, a sixth electric regulating valve 24, a seventh electric regulating valve 25 and an eighth electric regulating valve 14; The flue gas at the outlet of the induced draft fan is desulfurized and cooled in the desulfurization tower 1, and becomes saturated flue gas at the same time. The desulfurization slurry circulation pump 2 transports the slurry from the bottom layer of the desulfurization tower 1 to the upper layer for spraying. The flue gas at the outlet of the desulfurization tower 1 enters the flue gas spray tower 3 and is further sprayed and cooled by condensed water. After the saturated flue gas is cooled, a large amount of condensed water is generated and falls into the bottom of the spray tower. When the water level reaches a certain height, a part of it will be released into the desulfurization tower 1 through the condensed water discharge valve 4 as desulfurization water replenishment; the condensed water in the flue gas spray tower 3 is powered by the condensed water circulation pump 23 and transported to the first evaporator 5 of the compression heat pump and the second evaporator 22 of the absorption heat pump. The waste heat is extracted, the sixth electric regulating valve 24 and the seventh electric regulating valve 25 are respectively used to control the flow distribution into the first evaporator 5 and the second evaporator 22, the condensed water at the outlets of the first evaporator 5 and the second evaporator 22 are collected in the main pipe, and then divided into two ways to be supplied to the flue gas spray tower 3 and the working medium condenser 12 respectively, the fifth electric regulating valve 13 and the eighth electric regulating valve 14 are respectively used to control the condensed water flow distribution into the flue gas spray tower 3 and the working medium condenser 12; the condensed water at the outlets of the flue gas spray tower 3 and the working medium condenser 12 are collected in the main pipe and then continue to circulate repeatedly through the condensed water circulation pump 23; The working fluid in the compression heat pump cycle absorbs the low-grade waste heat of the condensed water in the first evaporator 5, and then is compressed by the compressor 6 and sent to the first condenser 7 to release heat and heat the return water of the heat network. The outlet condensed working fluid is depressurized by the first expansion valve 8 and sent back to the first evaporator 5; the working fluid in the low-temperature organic Rankine cycle power unit absorbs the waste heat of the heat network drainage in the waste heat evaporator 10 and is evaporated, and then enters the turbine 11 to do work to drive the compressor 6 and the solution pump 19 to operate, and the outlet exhaust steam working fluid is condensed by the working fluid condenser 12 and enters the organic working fluid pump to increase the pressure and then is sent back to the waste heat evaporator 10; the working fluid in the absorption heat pump circulation unit is heated and evaporated by the heat network drainage in the generator 15 and decomposed into a concentrated solution and water vapor. The concentrated solution is depressurized by the second expansion valve 16 and enters the solution heat exchanger 17 to transfer heat to the dilute solution on the other side, and then enters the absorber 18 to mix with the water from the second evaporator 22. The steam mixing releases heat to heat the return water of the heat network. The formed dilute solution is heated by the solution heat exchanger 17 and then pressurized by the solution pump 19 and then returned to the generator 15. The water vapor at the outlet of the generator 15 enters the second condenser 20 to heat the return water of the heat network again, and then enters the second evaporator 22 to evaporate into water vapor after being reduced in pressure by the third expansion valve 21. The water vapor enters the absorber 18 to mix with the concentrated solution; the return water of the heat network circulating water is pressurized by the heat network circulating water pump 29 and then sent to the first condenser 7 and the absorber 18 and condenser 20 to be heated and heated. The third electric regulating valve 30 and the fourth electric regulating valve 31 are used to adjust the flow distribution of the heat network circulating water entering the absorption heat pump unit and the compression heat pump unit respectively. The heat network circulating water at the outlets of the first condenser 7 and the second condenser 20 converges to the main pipe, and then enters the heat network heater 26 to be heated to the water supply temperature and supplied to the heat users; The heating extraction steam enters the shell side of the heat network heater 26 to heat the heat network circulating water, and the condensed heat network drain water is sent to the waste heat evaporator 10 and the generator 15 respectively to provide driving heat source for the low-temperature organic Rankine cycle power unit and the absorption heat pump unit. The first electric regulating valve 27 and the second electric regulating valve 28 are used to control the heat network drain water flow distribution entering the two units.

[0029] By arranging the turbine 11 in the low-temperature organic Rankine power cycle unit coaxially with the compressor 6 in the compression heat pump unit and the solution pump 19 in the absorption heat pump unit, the compressor 6 and the solution pump 19 are driven to operate by the work of the turbine 11, so as to realize the direct generation and output utilization of mechanical work, and realize the utilization of waste heat to drive the low-temperature organic Rankine power cycle unit to drive the compression heat pump unit and the absorption heat pump unit to operate; by recovering the tail flue gas through the flue gas waste heat deep recovery unit and sending it to the absorption heat pump unit and the compression heat pump unit to be indirectly heated as a low-temperature heat source, the return water of the heat network circulating water is preliminarily heated by the absorption heat pump unit and the compression heat pump unit, and then heated to the water supply temperature by the heat network heater 26, and then supplied to the heat users, not only the targeted utilization of high-grade thermal energy in the cogeneration unit is realized to achieve the purpose of efficient recovery, but also the deep recovery and utilization of low-grade thermal energy is realized, thereby further improving the energy efficiency of the thermal power unit, reducing energy consumption, and reducing emissions, which is of great significance for improving the economic benefits and clean transformation of the cogeneration unit.

[0030] See also Figure 2 The present invention provides a heating method using the above-mentioned combined heat pump heating system for deep waste heat utilization of thermal power units, comprising: S1: The exhaust gas from the exhaust fan outlet is desulfurized and cooled in the desulfurization tower 1 to become saturated exhaust gas, and then introduced into the exhaust gas spray tower 3 for cooling, so that the cooled exhaust gas is discharged, and the condensed water generated after cooling falls into the bottom of the spray tower 3; S2: The condensed water at the bottom of the spray tower 3 is divided into two paths, one of which is transported to the first evaporator 5 to extract the residual heat, and the other is transported to the second evaporator 22 to extract the residual heat; S3: The condensed water at the outlets of the first evaporator 5 and the second evaporator 22 is collected into a main pipe, and then divided into two paths, one of which is transported to the flue gas spray tower 3, and the other is transported to the working medium condenser 12, and the condensed water at the outlets of the flue gas spray tower 3 and the working medium condenser 12 is collected into the main pipe and continuously circulated and transported to the first evaporator 5 and the second evaporator 22; S4: The circulating water return from the heating network is divided into two paths, one of which is transported to the first condenser 7 and then heated by the heating network heater 26 and then transported to the heating network circulating water supply, and the other is transported to the absorber 18 and then heated by the second condenser 20 and the heating network heater 26 and then transported to the heating network circulating water supply; S5: After the working medium inside the first evaporator 5 absorbs the low-grade waste heat of the condensed water, it is transported to the first condenser 7 to release heat and heat the return water of the heat network, and then the condensed working medium at the outlet of the first condenser 7 returns to the first evaporator 5; S6: The working medium in the waste heat evaporator 10 enters the turbine 11 to perform work and drives the compressor 6 to operate, and the exhaust steam working medium at the outlet of the turbine 11 is condensed in the working medium condenser 12 and then sent back to the waste heat evaporator 10; S7: The concentrated solution in the generator 15 is transported to the hot end of the solution heat exchanger 17, and then transported to the absorber 18 to release heat and heat the return water of the heat network, so that the formed dilute solution is heated by the solution heat exchanger 17 and then returned to the generator 15; the water vapor at the outlet of the generator 15 is transported to the second condenser 20 to heat the return water of the heat network again, and then transported to the second evaporator 22 to evaporate into water vapor and enter the absorber 18 to mix with the concentrated solution; S8: The heating extraction steam enters the shell side of the heating network heater 26 to heat the heating network circulating water, and the condensed heating network drain water is respectively sent to the waste heat evaporator 10 and the generator 15 to provide a driving heat source to complete the heating.

[0031] In summary, the present invention provides a combined heat pump heating system and method for deep waste heat utilization of thermal power units. By efficiently coupling a low-temperature organic Rankine power cycle unit, a compression heat pump unit, an absorption heat pump unit and a flue gas waste heat deep recovery unit with the cogeneration heating network heating, dual utilization of the energy grade and quantity of the cogeneration unit is achieved, the energy utilization efficiency of the system is improved in a cascaded energy utilization manner, and a clean, efficient, energy-saving and low-carbon heating method is achieved.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A combined heat pump heating system for deep waste heat utilization of thermal power units, characterized in that: At least includes a low-temperature organic Rankine power cycle unit, a compression heat pump unit, an absorption heat pump unit and a flue gas waste heat deep recovery unit; The organic Rankine power cycle unit comprises a waste heat evaporator (10), a turbine (11) and an organic working fluid condenser (12) connected in sequence to a working fluid outlet of the waste heat evaporator (10), wherein the working fluid outlet of the organic working fluid condenser (12) is connected to a working fluid inlet of the waste heat evaporator (10); The compression heat pump unit comprises a first evaporator (5), a compressor (6) and a first condenser (7) which are connected in sequence to a working medium outlet of the first evaporator (5), and the working medium outlet of the first condenser (7) is connected to a working medium inlet of the first evaporator (5); The absorption heat pump unit comprises a generator (15), and a solution heat exchanger (17) and an absorber (18) connected in sequence to a concentrated solution outlet of the generator (15); a dilute solution outlet of the absorber (18) is connected in sequence to a cold end of the solution heat exchanger (17) and a solution inlet of the generator (15); a water vapor outlet of the generator (15) is connected in sequence to a second condenser (20) and a second evaporator (22); a water vapor outlet of the second evaporator (22) is connected to the absorber (18); The flue gas waste heat deep recovery unit comprises a desulfurization tower (1) and a flue gas spray tower (3) connected to the flue gas outlet of the desulfurization tower (1); the condensate outlet of the flue gas spray tower (3) is divided into two paths, one of which is connected to the first evaporator (5) and the other is connected to the second evaporator (22); the condensate outlets of the first evaporator (5) and the second evaporator (22) are combined into a mother pipe and divided into two paths, one of which is connected to the organic working fluid condenser (12) and then connected to the flue gas spray tower (3), and the other is directly connected to the flue gas spray tower (3); The return water output end of the heat network circulating water is divided into two paths, one of which is sequentially connected to the absorber (18) and the second condenser (20), the second condenser (20) is connected to the heat network heater (26), and the water outlet of the heat network heater (26) is connected to the heat network circulating water input end; the other path is sequentially connected to the first condenser (7) and the heat network heater (26); The heating extraction steam output end is connected to the shell side of the heating network heater (26); the shell side condensation heat network drain water of the heating network heater (26) is divided into two paths, one of which is connected to the waste heat evaporator (10) and the other is connected to the generator (15); the waste heat evaporator (10) and the generator (15) are both connected to the condenser of the unit.

2. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1 is characterized in that: The compressor (6) and the turbine (11) are arranged coaxially.

3. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1 is characterized in that: A first expansion valve (8) is provided between the first evaporator (5) and the first condenser (7).

4. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1 is characterized in that: The slurry outlet of the desulfurization tower (1) is connected to a desulfurization slurry circulation pump (2), and the output end of the desulfurization slurry circulation pump (2) is connected to the upper spray end of the desulfurization tower (1).

5. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1 is characterized in that: A solution pump (19) is provided between the cold end outlet of the solution heat exchanger (17) and the generator (15), and the solution pump (19) is coaxially arranged with the turbine (11).

6. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1 is characterized in that: A second expansion valve (16) is provided between the hot end of the solution heat exchanger (17) and the generator (15); and a third expansion valve (21) is provided between the second condenser (20) and the second evaporator (22).

7. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1 is characterized in that: A first electric regulating valve (27) is provided between the waste heat evaporator (10) and the condenser; and a second electric regulating valve (28) is provided between the generator (15) and the condenser.

8. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1, characterized in that: The condensate output end of the flue gas spray tower (3) is connected to the desulfurization tower (1), and a condensate discharge valve (4) is provided between the condensate output end of the flue gas spray tower (3) and the desulfurization tower (1).

9. The combined heat pump heating system for deep waste heat utilization of thermal power units according to claim 1, characterized in that: An organic working fluid pump (9) is provided between the waste heat evaporator (10) and the organic working fluid condenser; and a heating network circulating water pump (29) is provided at the heating network circulating water return output end.

10. A heating method using the combined heat pump heating system for deep waste heat utilization of thermal power units according to any one of claims 1 to 9, characterized in that: include: The exhaust gas from the exhaust fan outlet is desulfurized and cooled in a desulfurization tower (1) to become saturated exhaust gas, and then introduced into an exhaust gas spray tower (3) for cooling, so that the cooled exhaust gas is discharged and condensed water generated after cooling falls into the bottom of the spray tower (3); Condensed water at the bottom of the spray tower (3) is divided into two paths, one of which is transported to the first evaporator (5) to extract waste heat, and the other is transported to the second evaporator (22) to extract waste heat; Condensate at the outlets of the first evaporator (5) and the second evaporator (22) is collected into a main pipe and then divided into two paths, one of which is transported to the flue gas spray tower (3) and the other is transported to the working fluid condenser (12); and condensate at the outlets of the flue gas spray tower (3) and the working fluid condenser (12) is collected into the main pipe and continuously circulated and transported to the first evaporator (5) and the second evaporator (22); The circulating water return from the heating network is divided into two paths, one of which is transported to the first condenser (7) and then heated by the heating network heater (26) before being transported to the circulating water supply of the heating network, and the other is transported to the absorber (18) and then heated by the second condenser (20) and the heating network heater (26) before being transported to the circulating water supply of the heating network; After the working medium inside the first evaporator (5) absorbs the low-grade waste heat of the condensed water, it is transported to the first condenser (7) to release the heat and heat the return water of the heat network, and then the condensed working medium at the outlet of the first condenser (7) is returned to the first evaporator (5); The working fluid in the waste heat evaporator (10) enters the turbine (11) to perform work and drive the compressor (6) to operate, and the exhaust steam working fluid at the outlet of the turbine (11) is condensed in the working fluid condenser (12) and then sent back to the waste heat evaporator (10); The concentrated solution in the generator (15) is transported to the hot end of the solution heat exchanger (17), and then transported to the absorber (18) to release heat and heat the return water of the heat network, so that the formed dilute solution is heated by the solution heat exchanger (17) and then returned to the generator (15); the water vapor at the outlet of the generator (15) is transported to the second condenser (20) to heat the return water of the heat network again, and then transported to the second evaporator (22) to evaporate into water vapor and enter the absorber (18) to mix with the concentrated solution; The heating extraction steam enters the shell side of the heating network heater (26) to heat the heating network circulating water, and the condensed heating network drain water is respectively sent to the waste heat evaporator (10) and the generator (15) to provide a driving heat source, thereby completing the heating.

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