Combined heat pump heating system and method for deep waste heat utilization of thermal power units

Abstract

This 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 in cogeneration units. By combining absorption heat pump units and compression heat pump units, it achieves deep recovery of waste heat from the tail-end flue gas and allows it to participate in heating, reducing makeup water volume and heating costs. Simultaneously, it utilizes a low-temperature organic Rankine cycle unit driven by a heat network condensate with medium-grade heat energy to provide power to the system, achieving dual utilization of energy grade and quantity, thus improving system energy efficiency through energy cascade utilization. Furthermore, the high-quality condensate generated from flue gas cooling in the spray tower avoids heat exchanger blockage and corrosion problems when used as an intermediate transport medium for the low-temperature heat source of the absorption and compression heat pump units, reducing system operation and maintenance costs and further improving the economic benefits of cogeneration units. This invention addresses the problem of low waste heat recovery and utilization rates in existing cogeneration units.

Description

Technical Field

[0001] This invention relates to the field of clean heating technology, specifically to a combined heat pump heating system and method for deep waste heat utilization of thermal power units. Background Technology

[0002] In recent years, there has been a strong push to develop renewable new energy power systems, primarily based on wind and solar power. These new energy power systems are clean, low-carbon, efficient, safe, and possess sustainable development capabilities. They emphasize the widespread application of new energy sources, smart grids, and energy storage technologies to replace traditional thermal and nuclear power generation. However, due to the inherent volatility of new energy sources such as wind and solar power, their large-scale development and utilization will further exacerbate the imbalance between power supply and demand. Therefore, thermal power units, as a traditional power generation method, still play a crucial role in new energy power systems due to their stable output characteristics and flexible regulation capabilities. Waste heat utilization from thermal power units, as a key technology in energy conservation, is one of the important directions in technological upgrading. As a fundamental power source in the new energy power system, thermal power units play an important role in peak shaving, frequency regulation, and power supply. In northern regions, thermal power units are mostly used in the form of combined heat and power (CHP). In areas with high heating demand, waste heat recovery has a wide range of applications. The waste heat from the unit's heating steam extraction condensate and flue gas exists in the form of medium and low temperature waste heat. The efficient utilization of these two types of waste heat is of great significance to both the unit's energy efficiency level and the promotion of energy transformation.

[0003] In conventional cogeneration units, the condensate drain of the heating network has a temperature of around 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 a simple heat exchange form. Although heat is recovered, the heat energy grade is not utilized in a targeted manner. If the waste heat at this temperature level is used as a driving heat source, waste heat from other systems in the plant can be recovered additionally, increasing the amount of waste heat recovered. This utilizes both the heat and the heat energy grade, achieving the goal of efficient recovery. After passing through the desulfurization tower, the exhaust gas from the tail end of the power unit is usually saturated, carrying a large amount of water vapor. The latent heat contained in this gas is abundant, and the temperature of the tail-end flue gas is still relatively high, about 60℃~90℃. Currently, these high-temperature flue gases from thermal power units are directly discharged, resulting in a large waste of low-grade heat energy. If the temperature of this part of the flue gas can be reduced, most of the condensate can be recovered while recovering the low-temperature waste heat. This condensate can then be used for heating and water replenishment in systems such as heating networks, achieving deep waste heat utilization in the thermal cycle. This is of great significance for improving the energy efficiency of thermal power units, reducing energy consumption, and reducing emissions. Summary of the Invention

[0004] To address the problem of low waste heat recovery and utilization rate in existing cogeneration units, this invention provides a combined heat pump heating system and method for deep waste heat utilization in cogeneration units.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] This invention provides 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.

[0007] The organic Rankine power cycle unit includes a waste heat evaporator, a turbine and an organic working fluid condenser connected in sequence to the working fluid outlet of the waste heat evaporator, and the working fluid outlet of the organic working fluid condenser is connected to the working fluid inlet of the waste heat evaporator.

[0008] The compression heat pump unit includes a first evaporator and a compressor and a first condenser connected in sequence to the working fluid outlet of the first evaporator. The working fluid outlet of the first condenser is connected to the working fluid inlet of the first evaporator.

[0009] The absorption heat pump unit includes a generator and a solution heat exchanger and an absorber connected in sequence to the concentrated solution outlet of the generator. The dilute solution outlet of the absorber is connected in sequence to the cold end of the solution heat exchanger and the solution inlet of the generator. The water vapor outlet of the generator is connected in sequence to a second condenser and a second evaporator. The water vapor outlet of the second evaporator is connected to the absorber.

[0010] The deep waste heat recovery unit for flue gas includes 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 paths, 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 main pipe and divided into two paths, one of which is connected to the organic working fluid condenser and then to the flue gas spray tower, and the other is directly connected to the flue gas spray tower.

[0011] The return water output of the heating network circulating water is divided into two paths. One path is connected to the absorber and the second condenser in sequence. The second condenser is connected to the heating network heater, and the water outlet of the heating network heater is connected to the heating network circulating water input. The other path is connected to the first condenser and the heating network heater in sequence.

[0012] The heating extraction steam output end is connected to the shell side of the heating network heater. The condensate drain of the heating network on the shell side is divided into two paths, one of which is connected to the waste heat evaporator and the other is connected to the generator. Both the waste heat evaporator and the generator are connected to the condenser of the unit.

[0013] Optionally, the compressor is coaxially arranged with the turbine.

[0014] Optionally, a first expansion valve is provided between the first evaporator and the first condenser.

[0015] 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.

[0016] 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.

[0017] Optionally, a second expansion valve is provided between the hot end of the solution heat exchanger and the generator; a third expansion valve is provided between the second condenser and the second evaporator.

[0018] 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.

[0019] Optionally, the condensate outlet of the flue gas scrubbing tower is connected to the desulfurization tower, and a condensate discharge valve is provided between the condensate outlet of the flue gas scrubbing tower and the desulfurization tower.

[0020] Optionally, an organic working fluid pump is provided between the waste heat evaporator and the organic working fluid condenser; a heating network circulating water pump is provided at the return water output end of the heating network.

[0021] The present invention also provides a heating method utilizing the above-mentioned combined heat pump heating system for deep waste heat utilization of thermal power units, comprising:

[0022] The flue gas from the exhaust fan outlet is desulfurized and cooled in the desulfurization tower, becoming saturated flue gas, and then introduced into the flue gas spray tower for further cooling. The cooled flue gas is then discharged, and the condensate produced after cooling falls to the bottom of the spray tower.

[0023] The condensate at the bottom of the spray tower is divided into two paths: one path is sent to the first evaporator to extract waste heat, and the other path is sent to the second evaporator to extract waste heat.

[0024] The condensate from the outlets of the first and second evaporators is collected into the main pipe, and then split into two paths. One path is sent to the flue gas scrubbing tower, and the other path is sent to the working fluid condenser. The condensate from the outlets of the flue gas scrubbing tower and the working fluid condenser is collected into the main pipe and then circulated to the first and second evaporators.

[0025] The circulating water of the heating network is divided into two paths. One path is sent to the first condenser, heated by the heating network heater, and then sent to the heating network circulating water supply. The other path is sent to the absorber, heated by the second condenser and the heating network heater, and then sent to the heating network circulating water supply.

[0026] After the working fluid inside the first evaporator absorbs the low-grade waste heat of the condensate, it is transported to the first condenser to release heat and heat the return water of the heating network, so that the condensate at the outlet of the first condenser returns to the first evaporator.

[0027] The working fluid in the waste heat evaporator enters the turbine to do work and drive the compressor. The waste steam working fluid at the turbine outlet is condensed in the working fluid condenser and sent back to the waste heat evaporator.

[0028] The concentrated solution in the generator is sent to the hot end of the solution heat exchanger and then to the absorber to release heat and heat the return water of the heating network. The resulting dilute solution is heated by the solution heat exchanger and then returned to the generator. The steam from the generator outlet is sent to the second condenser to reheat the return water of the heating network, and then sent to the second evaporator to evaporate into steam and enter the absorber to mix with the concentrated solution.

[0029] Heating steam is drawn into the shell side of the heating network heater to heat the circulating water in the heating network. The condensate from the heating network is then sent to the waste heat evaporator and generator to provide the driving heat source, thus completing the heating supply. Compared with the prior art, this invention has the following advantages:

[0030] This 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 deep waste heat recovery unit for flue gas. The low-temperature organic Rankine power cycle unit uses a power cycle turbine to drive the compressor, directly generating and utilizing mechanical work. The deep waste heat recovery unit further recovers waste heat and condensate from the saturated flue gas after it has been sprayed through a desulfurization tower, using the recovered condensate as makeup water for the desulfurization tower. The circulating water after waste heat recovery is indirectly heated by the evaporators in the absorption and compression heat pump units as a low-temperature heat source. The return water from the heating network is initially heated by the absorption and compression heat pump units, then further heated to the supply water temperature by the heating network heater before being supplied to the heat users. This heating system achieves deep recovery of waste heat from the tail flue gas by combining absorption heat pump units and compression heat pump units, enabling it to participate in heating and reducing makeup water volume and heating costs. Simultaneously, it utilizes a low-temperature organic Rankine cycle unit driven by a heat network condensate pump with medium-grade heat energy to provide power to the system, achieving dual utilization of energy grade and quantity. This cascaded energy utilization improves the system's energy efficiency. Furthermore, the high-quality condensate generated from flue gas cooling in the spray tower avoids heat exchanger blockage and corrosion when used as an intermediate transport medium for the low-temperature heat sources of the absorption and compression heat pump units, reducing system operation and maintenance costs and further enhancing the economic benefits of the cogeneration unit.

[0031] This invention also provides a heating method for a combined heat pump heating system for deep waste heat recovery from thermal power units, as described above. This method involves desulfurizing and cooling the flue gas from the exhaust fan outlet through a desulfurization tower to create saturated flue gas, which is then introduced into a flue gas spray tower for further cooling. The cooled flue gas is then discharged, and the condensate generated after cooling is sent in two separate paths to a compression heat pump unit and an absorption heat pump unit, respectively, to be utilized as a low-temperature heat source at the heating end. By using the condensate drain of the heat network with medium-grade thermal energy as a power source to drive the organic Rankine cycle unit, the system is powered. This achieves efficient coupling of the compression heat pump unit, the absorption heat pump unit, the deep waste heat recovery unit, and the low-temperature organic Rankine power cycle unit, realizing dual utilization of energy grade and quantity. Furthermore, by using energy cascade utilization, the system's energy efficiency is improved, achieving a clean, efficient, energy-saving, and low-carbon heating method. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a combined heat pump heating system for deep waste heat utilization of thermal power units according to the present invention.

[0033] Figure 2 This is a flowchart of a combined heat pump heating method for deep waste heat utilization of thermal power units according to the present invention.

[0034] 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 Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0039] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0041] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0042] Example 1

[0043] See Figure 1 The present invention discloses a combined heat pump heating system for deep waste heat utilization of thermal power units, which includes 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.

[0044] The organic Rankine power cycle unit includes a waste heat evaporator 10, a turbine 11 and an organic working fluid condenser 12 connected in sequence 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.

[0045] The compression heat pump unit includes a first evaporator 5 and a compressor 6 and a first condenser 7 connected in sequence to the working fluid outlet of the first evaporator 5. The working fluid outlet of the first condenser 7 is connected to the working fluid inlet of the first evaporator 5. A first expansion valve 8 is provided between the first evaporator 5 and the first condenser 7.

[0046] The absorption heat pump unit includes a generator 15 and a solution heat exchanger 17 and an absorber 18 connected in sequence to the concentrated solution outlet of the generator 15. The dilute solution outlet of the absorber 18 is connected in sequence to the cold end of the solution heat exchanger 17 and the solution inlet of the generator 15. A solution pump 19 is provided between the cold end outlet of the solution heat exchanger 17 and the generator 15. 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 connected in sequence to a second condenser 20 and a second evaporator 22. The water vapor outlet of the second evaporator 22 is connected to the absorber 18.

[0047] The deep waste heat recovery unit for flue gas 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 outlet 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 outlet 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 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 main 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.

[0048] The return water output of the heating network is divided into two paths. One path is connected to the absorber 18 and the second condenser 20 in sequence. The second condenser 20 is connected to the heating network heater 26. The water outlet of the heating network heater 26 is connected to the heating network circulating water input. The other path is connected to the first condenser 7 and the heating network heater 26 in sequence.

[0049] The heating extraction steam output end is connected to the shell side of the heat network heater 26. The heat network heater 26 shell side condenses the heat network drain 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.

[0050] This invention achieves deep recovery of waste heat from tail-end flue gas by combining absorption heat pump units and compression heat pump units, enabling it to participate in heating and reducing makeup water volume and heating costs. Simultaneously, it utilizes a low-temperature organic Rankine power cycle unit driven by a heat network with medium-grade heat energy to provide power to the system, achieving dual utilization of energy quality and quantity. This cascaded energy utilization improves the system's energy efficiency. Furthermore, the high-quality condensate generated from flue gas cooling in the spray tower avoids heat exchanger blockage and corrosion when used as an intermediate transport medium for the low-temperature heat source of the absorption and compression heat pump units, reducing system operation and maintenance costs and further enhancing the economic benefits of the cogeneration unit.

[0051] Example 2

[0052] See Figure 1 The present invention discloses a combined heat pump heating system for deep waste heat utilization of thermal power units, which includes 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.

[0053] The low-temperature organic Rankine power cycle unit includes 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 flowing in the internal loop of the low-temperature organic Rankine power cycle unit is an organic working fluid with a low boiling point and saturation temperature.

[0054] The compression heat pump unit includes a first evaporator 5, a compressor 6, a first condenser 7, and a first expansion valve 8; the fluid flowing in the internal loop of the compression heat pump unit is an organic compound.

[0055] The absorption heat pump unit includes 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; the fluid flowing in the internal loop of the absorption heat pump unit is a lithium bromide solution or other compound working fluid.

[0056] The flue gas waste heat recovery unit includes a desulfurization tower 1, a desulfurization slurry circulation pump 2, a spray tower 3, and a condensate discharge valve 4.

[0057] 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.

[0058] The flue gas from the exhaust fan outlet is desulfurized and cooled in desulfurization tower 1, becoming saturated flue gas. Desulfurization slurry circulation pump 2 transports the slurry from the bottom of desulfurization tower 1 to the upper spray layer. The flue gas from the outlet of desulfurization tower 1 enters the flue gas spray tower 3, where it is further sprayed and cooled by condensate. After cooling, a large amount of condensate is generated and falls to the bottom of the spray tower. When the water level reaches a certain height, a portion is released into desulfurization tower 1 as makeup water through condensate discharge valve 4. The condensate in the flue gas spray tower 3 is then pumped by condensate circulation pump 23 to the first evaporator 5 of the compression heat pump and the second evaporator 22 of the absorption heat pump. Waste heat is extracted, and the sixth electric regulating valve 24 and the seventh electric regulating valve 25 are used to control the flow distribution into the first evaporator 5 and the second evaporator 22, respectively. The condensate from the outlets of the first evaporator 5 and the second evaporator 22 is collected into the main pipe and then distributed to the flue gas spray tower 3 and the working fluid condenser 12, respectively. The fifth electric regulating valve 13 and the eighth electric regulating valve 14 are used to control the flow distribution of the condensate entering the flue gas spray tower 3 and the working fluid condenser 12, respectively. The condensate from the outlets of the flue gas spray tower 3 and the working fluid condenser 12 is collected into the main pipe and then circulated again by the condensate circulation pump 23.

[0059] In the compression heat pump cycle, the working fluid absorbs low-grade waste heat from condensate in the first evaporator 5, then is compressed by the compressor 6 and sent to the first condenser 7 to release heat and heat the return water of the heating network. The condensate at the outlet is depressurized by the first expansion valve 8 and sent back to the first evaporator 5. In the low-temperature organic Rankine cycle power unit, the working fluid absorbs waste heat from the condensate drain in the heating network in the waste heat evaporator 10 and is evaporated. It then enters the turbine 11 to drive the compressor 6 and the solution pump 19. The exhaust working fluid at the outlet is condensed by the working fluid condenser 12 and pressurized by the organic working fluid pump before being sent back to the waste heat evaporator 10. In the absorption heat pump cycle unit, the working fluid is heated and evaporated by the condensate drain in the heating network in the generator 15, decomposing 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. It then enters the absorber 18 to react with the water from the second evaporator 22. Steam mixes and releases heat to heat the return water of the heating network. The resulting dilute solution is heated by the solution heat exchanger 17 and then pressurized by the solution pump 19 before returning to the generator 15. The steam at the outlet of the generator 15 enters the second condenser 20 to reheat the return water of the heating network. Then, after being depressurized by the third expansion valve 21, it enters the second evaporator 22 to evaporate into steam. The steam enters the absorber 18 to mix with the concentrated solution. The return water of the heating network is pressurized by the heating network circulating water pump 29 and sent to the first condenser 7, the absorber 18, and the condenser 20 respectively to be heated. The third electric regulating valve 30 and the fourth electric regulating valve 31 are used to regulate the flow distribution of the heating network circulating water entering the absorption heat pump unit and the compression heat pump unit, respectively. The heating network circulating water at the outlet of the first condenser 7 and the second condenser 20 is collected into the main pipe and then enters the heating network heater 26 to be heated to the supply water temperature and supplied to the heat users.

[0060] Heating steam is drawn into the shell side of the heating network heater 26 to heat the heating network circulating water. The condensed heating network condensate 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 flow distribution of the heating network condensate entering the two units.

[0061] By coaxially connecting the turbine 11 in the low-temperature organic Rankine power cycle unit with the compressor 6 in the compression heat pump unit and the solution pump 19 in the absorption heat pump unit, the turbine 11 drives the compressor 6 and the solution pump 19, realizing the direct generation and output of mechanical work. This achieves the utilization of waste heat to drive the operation of the low-temperature organic Rankine power cycle unit, which in turn drives the compression heat pump unit and the absorption heat pump unit. 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 as a low-temperature heat source for indirect heating, the return water of the heating network is preheated by the absorption heat pump unit and the compression heat pump unit, and then heated to the supply water temperature by the heating network heater 26 before being supplied to the heat users. This not only realizes the targeted utilization of high-grade heat energy in the cogeneration unit and achieves the goal of efficient recovery, but also realizes the deep recovery and utilization of low-grade heat energy, thereby further improving the energy efficiency of the thermal power unit, reducing energy consumption, and reducing emissions. This is of great significance for improving the economic benefits of cogeneration unit operation and clean energy transformation.

[0062] See Figure 2 The present invention provides a heating method utilizing the above-mentioned combined heat pump heating system for deep waste heat utilization of thermal power units, comprising:

[0063] S1: The flue gas from the exhaust fan outlet is desulfurized and cooled in desulfurization tower 1, becoming saturated flue gas, and then introduced into flue gas spray tower 3 for further cooling. The cooled flue gas is then discharged, and the condensate generated after cooling falls into the bottom of the spray tower 3.

[0064] S2: The condensate at the bottom of the spray tower 3 is divided into two paths, one of which is sent to the first evaporator 5 to be extracted for waste heat, and the other is sent to the second evaporator 22 to be extracted for waste heat.

[0065] S3: The condensate from the outlets of the first evaporator 5 and the second evaporator 22 is collected into the main pipe, and then split into two paths, one of which is sent to the flue gas spray tower 3 and the other is sent to the working fluid condenser 12. The condensate from the outlets of the flue gas spray tower 3 and the working fluid condenser 12 is collected into the main pipe and continues to be circulated to the first evaporator 5 and the second evaporator 22.

[0066] S4: Divide the circulating water of the heating network into two paths. One path is sent to the first condenser 7, heated by the heating network heater 26, and then sent to the heating network circulating water supply. The other path is sent to the absorber 18, heated by the second condenser 20 and the heating network heater 26, and then sent to the heating network circulating water supply.

[0067] S5: After the working fluid inside the first evaporator 5 absorbs the low-grade waste heat of the condensate, it is sent to the first condenser 7 to release heat and heat the return water of the heating network, so that the condensate at the outlet of the first condenser 7 returns to the first evaporator 5.

[0068] S6: The working fluid in the waste heat evaporator 10 is fed into the turbine 11 to do work and drive the compressor 6 to run. The exhaust working fluid at the outlet of the turbine 11 is condensed by the working fluid condenser 12 and sent back to the waste heat evaporator 10.

[0069] S7: The concentrated solution in generator 15 is transported to the hot end of solution heat exchanger 17 and then to absorber 18 to release heat and heat the return water of the heating network. The resulting dilute solution is heated by solution heat exchanger 17 and then returned to generator 15. The water vapor at the outlet of generator 15 is transported to the second condenser 20 to reheat the return water of the heating network, and then transported to the second evaporator 22 to evaporate into water vapor and enter absorber 18 to mix with the concentrated solution.

[0070] S8: The heating steam is drawn into the shell side of the heating network heater 26 to heat the heating network circulating water, and the condensed heating network condensate is sent to the waste heat evaporator 10 and the generator 15 respectively to provide driving heat source and complete the heating.

[0071] In summary, this invention provides a combined heat pump heating system and method for deep waste heat utilization of cogeneration units. By efficiently coupling a low-temperature organic Rankine power cycle unit, a compression heat pump unit, an absorption heat pump unit, and a deep waste heat recovery unit from flue gas with a cogeneration heating network, it achieves dual utilization of the energy grade and quantity of the cogeneration unit. This improves the system's energy utilization efficiency through energy cascade utilization, realizing a clean, efficient, energy-saving, and low-carbon heating method.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A combined heat pump heating system for deep waste heat utilization of a thermoelectric unit, characterized in that, The unit 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. The organic Rankine power cycle unit comprises a waste heat evaporator (10), a turbine (11) connected to the working medium outlet of the waste heat evaporator (10) and an organic working medium condenser (12) connected to the working medium outlet of the turbine (11). The compression heat pump unit comprises a first evaporator (5), a compressor (6) connected to the working medium outlet of the first evaporator (5) and a first condenser (7) connected to the working medium outlet of the compressor (6). The absorption heat pump unit comprises a generator (15), a solution heat exchanger (17) connected to the concentrated solution outlet of the generator (15) and an absorber (18) connected to the dilute solution outlet of 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 of which is connected to the second evaporator (22). The condensate outlet of the first evaporator (5) and the second evaporator (22) is combined into one main pipe and divided into two paths, one of which is connected to the organic working medium condenser (12) and then connected to the flue gas spray tower (3), and the other of which is directly connected to the flue gas spray tower (3).

2. The combined heat pump heating system for deep waste heat utilization of a thermoelectric unit according to claim 1, characterized in that, The heat network circulating water return output end is divided into two paths, one of which is connected to the absorber (18) and the second condenser (20) in sequence, and the other of which is connected to the first condenser (7) and the heat network heater (26) in sequence.

3. The combined heat pump heating system for deep waste heat utilization of a thermoelectric unit according to claim 1, characterized in that, The heating steam extraction output end is connected to the shell side of the heat network heater (26), and the condensate heat network drain of the shell side 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 of which is connected to the generator (15).

4. The combined heat pump heating system for deep waste heat utilization of a thermoelectric unit according to claim 1, characterized in that, The compressor (6) is coaxially arranged with the turbine (11).

5. The combined heat pump heating system for deep waste heat utilization of a thermoelectric unit according to claim 1, characterized in that, A first expansion valve (8) is arranged between the first evaporator (5) and the first condenser (7). The slurry outlet of the desulfurization tower (1) is connected to a desulfurization slurry circulating pump (2), and the output end of the desulfurization slurry circulating pump (2) is connected to the upper spray end of the desulfurization tower (1). 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) is coaxially arranged with the turbine (11).

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

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

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

9. The combined heat pump heating system for deep waste heat utilization of a thermoelectric unit according to claim 1, characterized in that, The waste heat evaporator (10) is provided with an organic working medium pump (9) between the organic working medium condenser; and the heat network circulating water return water output end is provided with a heat network circulating water pump (29).

10. A heating method using the combined heat pump heating system for cogeneration unit deep waste heat utilization according to any one of claims 1-9, characterized in that, The method comprises the following steps: The flue gas from the induced draft fan is desulfurized and cooled in the desulfurization tower (1) to become saturated flue gas, and is introduced into the flue gas spray tower (3) for cooling, so that the cooled flue gas is discharged, and the condensed water generated after cooling falls into the bottom of the spray tower (3); 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 waste heat, and the other of which is transported to the second evaporator (22) to extract waste heat; The condensed water at the outlet 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 of which is transported to the working medium condenser (12), and the condensed water at the outlet of the flue gas spray tower (3) and the working medium condenser (12) is collected into a main pipe and continuously transported to the first evaporator (5) and the second evaporator (22); The heat network circulating water return water is divided into two paths, one of which is transported to the first condenser (7) and then heated by the heat network heater (26) and transported to the heat network circulating water supply, and the other of which is transported to the absorber (18) and then heated by the second condenser (20) and the heat network heater (26) and transported to the heat network circulating water supply; The working medium in the first evaporator (5) absorbs the low-grade waste heat of the condensed water, and is then transported to the first condenser (7) to heat the heat network return water, and the condensed working medium at the outlet of the first condenser (7) is returned to the first evaporator (5); The working medium in the waste heat evaporator (10) is driven into the turbine (11) to work and drive the compressor (6) to operate, and the exhaust working medium at the outlet of the turbine (11) is condensed by the working medium 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 the absorber (18) to heat the heat network return water, and 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 heat network return water again, and then is transported to the second evaporator (22) to evaporate into water vapor and enter the absorber (18) to mix with the concentrated solution; The heating steam is introduced into 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 into the waste heat evaporator (10) and the generator (15) to provide driving heat sources, and the heating is completed.

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