A method and system for three-stage air preheating using the waste heat of a waste power station

Abstract

The present invention relates to a method for air preheating in a waste power station, particularly a method for three-stage air preheating by using the waste heat of the waste power station, which comprises the following steps: the primary air is heated by passing through a primary heater, a secondary heater and a tertiary heater in sequence and then sent to the waste incineration boiler for auxiliary combustion; wherein, the heating heat source of the primary heater is selected from the high-temperature circulating water at the outlet of the flue gas heat exchanger or the high-temperature heat medium water at the outlet of the hot water side of the absorption heat pump according to the different temperatures of the circulating water at the outlet of the condenser; the heating heat source of the secondary heater comes from the first-stage extraction steam a of the steam turbine; the heating heat source of the tertiary heater comes from the extraction steam of the steam drum. This method realizes the deep and sustainable recovery and utilization of the waste heat of the waste power station, improves the comprehensive efficiency of the generating set; at the same time, the drain water of the tertiary heater is transported to the waste pit heat exchanger to further exchange heat with the waste, which not only promotes the full fermentation of the waste and its full combustion in the incineration boiler, but also realizes the cascade utilization of energy.

Description

Technical Field

[0001] The invention relates to an air preheating method for a garbage power plant, in particular to a method and a system for performing three-stage air preheating by utilizing waste heat from a garbage power plant. Background Art

[0002] The exhaust gas temperature at the outlet of the waste heat boiler of garbage incineration is designed to be 190℃~210℃. However, with the continuous improvement of living standards, the calorific value of domestic garbage has gradually increased. At the same time, due to the coking and ash accumulation in the boiler, the exhaust gas temperature at the outlet of the waste heat boiler of some garbage incineration power stations is even as high as 240℃~260℃, which leads to a decrease in the thermal efficiency of the whole plant and a waste of energy.

[0003] In addition, when the temperature in some garbage power plants is high in summer and autumn, the cooling water temperature at the condenser circulating water outlet reaches about 35°C, and some are even close to 40°C. This heat is released into the environment through heat exchange in the mechanical ventilation cooling tower, causing a certain amount of energy waste.

[0004] Secondly, the primary air heating of garbage power plants currently generally adopts a two-stage heating air preheater. The low-temperature heating heat source of this air preheater comes from the first stage of steam extraction from the turbine body, and the high-temperature heating heat source comes from the steam extraction from the boiler drum. The water drain from the two-stage heaters is returned to the deaerator. Although this method makes the primary air temperature reach the designed air temperature and maintains the stable combustion of the garbage incineration boiler, both low-temperature heating steam and high-temperature heating steam are high-grade energy steam. All of them are used to heat the primary air, which is easy to cause the loss of part of the unit's high-grade energy and reduce the unit's efficiency. On the other hand, the water drained after the boiler drum is extracted and released still has a relatively high temperature, generally in a wet steam state, and is directly recovered to the deaerator, so that the deaerator cannot completely recover the water drain in the circulation system, resulting in energy waste. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method and system for using waste heat from a garbage power plant to perform three-stage air preheating, which can switch the heater heating source according to the different circulating water temperatures at the condenser outlet, realize deep sustainable recycling of waste heat from the garbage power plant, improve the overall efficiency of the generator set, and further exchange heat between the drain water from the heater and the garbage, which not only promotes full fermentation of the garbage, but also realizes the cascade utilization of energy. The specific technical solution is:

[0006] A method for three-stage air preheating using the waste heat of a waste power station, characterized by comprising the following steps: The primary air is heated by passing through a primary heater, a secondary heater, and a tertiary heater in sequence and then sent to the waste incineration boiler for auxiliary combustion; wherein, the heating heat source of the primary heater is selected from the high-temperature circulating water at the outlet of the flue gas heat exchanger or the high-temperature heat medium water at the outlet of the hot water side of the absorption heat pump according to the different temperatures of the circulating water at the outlet of the condenser; the heating heat source of the secondary heater comes from the first-stage extraction steam a of the steam turbine; the heating heat source of the tertiary heater comes from the extraction steam of the steam drum.

[0007] Further, according to the different temperatures of the circulating water at the outlet of the condenser, by switching the first electric valve, the second electric valve, the third electric valve, the fourth electric valve, the fifth electric valve, the sixth electric valve, the seventh electric valve, and the eighth electric valve, and at the same time adjusting the working mode of the absorption heat pump, the heating heat source of the primary heater in the three-stage air preheater is changed.

[0008] Further, when the temperature of the circulating water at the outlet of the condenser is greater than or equal to the preset temperature, the first electric valve and the sixth electric valve are closed, and the second electric valve, the third electric valve, the fourth electric valve, the fifth electric valve, the seventh electric valve, and the eighth electric valve are opened, so that the high-temperature circulating water at the outlet of the flue gas heat exchanger serves as the high-temperature heat source of the absorption heat pump, a part of the circulating water at the outlet of the condenser serves as the low-temperature heat source of the absorption heat pump, the absorption heat pump starts to work, and the high-temperature heat medium water generated at the outlet of the hot water side enters the primary heater to heat the primary air, and the heated drain water returns to the inlet of the hot water side of the absorption heat pump; when the temperature of the circulating water at the outlet of the condenser is less than the preset temperature, the first electric valve and the sixth electric valve are opened, the second electric valve, the third electric valve, the fourth electric valve, the fifth electric valve, the seventh electric valve, and the eighth electric valve are closed, the absorption heat pump stops working, and the high-temperature circulating water at the outlet of the flue gas heat exchanger serves as the heat source and directly enters the primary heater to heat the primary air, and the heated drain water returns to the inlet of the flue gas heat exchanger through the first circulating pump.

[0009] Further, the hot fluid of the flue gas heat exchanger is the flue gas at the outlet of the dust collector. When the high-temperature heat medium water at the outlet of the hot water side of the absorption heat pump serves as the heating heat source of the primary heater, the cooling water at the high-temperature heat source outlet of the absorption heat pump is boosted by the first circulating pump and serves as the cold fluid of the flue gas heat exchanger; when the high-temperature circulating water at the outlet of the flue gas heat exchanger serves as the heating heat source of the primary heater, the drain water of the primary heater is boosted by the first circulating pump and serves as the cold fluid of the flue gas heat exchanger.

[0010] Further, a part of the circulating water at the outlet of the condenser enters the low-temperature heat source inlet of the absorption heat pump through the seventh electric valve, and a part directly enters the mechanical draft cooling tower for cooling; the cooling water at the low-temperature outlet of the absorption heat pump is mixed with the circulating water cooled by the mechanical draft cooling tower through the second circulating water pump and the eighth electric valve and then enters the condenser to cool the exhaust steam of the steam turbine.

[0011] Further, the drain water of the extracted steam from the steam drum after heat exchange in the three-stage heater is transported to the waste pit heat exchanger to further exchange heat with the waste, and the condensed water c after heat exchange is mixed with the condensed water at the outlet of the low-pressure heater through a pipeline and then sent to the deaerator.

[0012] Further, the drain water b of the first-stage extracted steam a of the steam turbine after heat exchange in the second-stage heater returns to the deaerator.

[0013] A system for three-stage air preheating using the waste heat of a waste power station, comprising: a three-stage air preheater, a flue gas heat exchanger, an absorption heat pump, a deaerator, a steam turbine, a steam drum, a deaerator and a condenser, the condenser is connected to the absorption heat pump; the three-stage air preheater includes a first-stage heater, a second-stage heater and a third-stage heater connected in sequence; the first-stage heater is respectively connected to the flue gas heat exchanger and the absorption heat pump; the second-stage heater is respectively connected to the steam turbine and the deaerator; the third-stage heater is connected to the steam drum.

[0014] Further, it includes a waste pit heat exchanger, and the third-stage heater is connected to the waste pit heat exchanger.

[0015] Further, a first electric valve and a sixth electric valve are installed between the first-stage heater and the flue gas heat exchanger; a third electric valve and a fourth electric valve are installed between the first-stage heater and the absorption heat; a second electric valve and a fifth electric valve are installed between the flue gas heat exchanger and the absorption heat pump; a seventh electric valve and an eighth electric valve are installed between the absorption heat pump and the condenser.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention provides a method and a system for three-stage air preheating using the waste heat of a waste power station. According to the different temperatures of the circulating water at the outlet of the condenser, the dual waste heat of the flue gas of the waste power station and the circulating water at the outlet of the condenser is utilized to switch the heating heat source of the first-stage heater in the three-stage air preheater, realizing the deep and sustainable recovery and utilization of the waste heat of the waste power station and improving the energy utilization efficiency of the unit; at the same time, the three-stage air preheater realizes the step-by-step heating of the primary air, reducing the steam consumption of the high-grade steam of the first-stage extracted steam of the steam turbine and the extracted steam of the steam drum, enabling more high-grade steam to enter the steam turbine to do work, increasing the work done by the steam turbine, and improving the comprehensive efficiency of the generating set.

[0018] 2. The present invention provides a method and a system for three-stage air preheating by using the waste heat of a waste power station. The condensed water after the steam extraction from the steam drum exchanges heat through three-stage heaters enters the waste pit heat exchanger, further exchanges heat with the waste, and after the heat exchange, the condensed water is mixed with the condensed water at the outlet of the low-pressure heater and then enters the deaerator. This method not only fully promotes the fermentation of the waste, enabling the waste to burn fully in the incinerator boiler, but also avoids the boiling phenomenon of the deaerator caused by too high temperature of the condensed water, ensures the deaeration effect, and realizes the cascade utilization of energy at the same time. Brief Description of the Drawings

[0019] Figure 1 It is a schematic diagram of a system for a method of three-stage air preheating by using the waste heat of a waste power station.

[0020] Wherein: 1 - waste incinerator boiler, 2 - steam drum, 3 - steam turbine, 4 - generator, 5 - condenser, 6 - low-pressure heater, 7 - deaerator, 8 - dust collector, 9 - flue gas heat exchanger, 10 - chimney, 11 - mechanical draft cooling tower, 12 - three-stage air preheater, 121 - first-stage heater, 122 - second-stage heater, 123 - third-stage heater, 13 - absorption heat pump, 14 - waste pit heat exchanger, 15 - first circulating water pump, 16 - second circulating water pump, 17 - first electric valve, 18 - second electric valve, 19 - third electric valve, 20 - fourth electric valve, 21 - fifth electric valve, 22 - sixth electric valve, 23 - seventh electric valve, 24 - eighth electric valve. Detailed Embodiments

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0023] It should be noted that in the embodiments, the "primary air" refers to the air preheated through the three-stage air preheater.

[0024] Embodiment

[0025] As Figure 1 shown, a method for three-stage air preheating by utilizing the waste heat of a waste power station includes the following steps: The heating heat source of the primary heater 121 is switched by the first electric valve 17, the second electric valve 18, the third electric valve 19, the fourth electric valve 20, the fifth electric valve 21, the sixth electric valve 22, the seventh electric valve 23, and the eighth electric valve 24 according to the temperature of the circulating water at the outlet of the condenser 5, and at the same time, the working mode of the absorption heat pump 13 is adjusted to select the high-temperature circulating water at the outlet of the flue gas heat exchanger 9 or the high-temperature heat medium water at the hot water side outlet of the absorption heat pump 13.

[0026] When the temperature of the circulating water at the outlet of the condenser 5 is greater than or equal to the preset temperature, the first electric valve 17 and the sixth electric valve 22 are closed, and the second electric valve 18, the third electric valve 19, the fourth electric valve 20, the fifth electric valve 21, the seventh electric valve 23, and the eighth electric valve 24 are opened, so that the high-temperature circulating water at the outlet of the flue gas heat exchanger 9 serves as the high-temperature heat source of the absorption heat pump 13, a part of the circulating water at the outlet of the condenser 5 serves as the low-temperature heat source of the absorption heat pump 13, the absorption heat pump 13 starts to work, and the high-temperature heat medium water generated at the hot water side outlet of the absorption heat pump 13 enters the primary heater 121 as a heat source to heat the primary air, and the heated drain water returns to the inlet of the hot water side of the absorption heat pump (13). By using the high-temperature circulating water generated by the flue gas heat exchanger 9 and the circulating water at the outlet of the condenser 5 as the high-temperature heat source and the low-temperature heat source of the absorption heat pump 13 respectively to produce high-temperature heat medium water as the heating heat source of the primary heater 121, the deep recovery and utilization of the dual waste heat of the waste power station flue gas and the circulating water at the outlet of the condenser are realized, and the energy utilization efficiency of the unit is improved;

[0027] When the temperature of the circulating water at the outlet of the condenser 5 is less than the preset temperature, the first electric valve 17 and the sixth electric valve 22 are opened, the second electric valve 18, the third electric valve 19, the fourth electric valve 20, the fifth electric valve 21, the seventh electric valve 23, and the eighth electric valve 24 are closed, the absorption heat pump 13 stops working, and the high-temperature circulating water at the outlet of the flue gas heat exchanger 9 enters the primary heater 121 directly as a heat source to heat the primary air, and the heated drain water returns to the inlet of the flue gas heat exchanger 9 through the first circulating pump 15. By using the high-temperature circulating water generated by heat exchange with the flue gas in the flue gas heat exchanger 9 as the heating heat source of the primary heater 121, the deep recovery and utilization of the waste heat of the waste power station flue gas are realized, and the energy utilization efficiency of the unit is improved.

[0028] In this embodiment, the preset temperature is set according to the change in the temperature of the circulating water at the outlet of the condenser 5 caused by different seasons and temperatures. The preset temperature can be any temperature between 30°C and 35°C. Preferably, it can be 32°C.

[0029] The heating heat source of the secondary heater 122 comes from the first-stage extraction steam a of the steam turbine 3, and the generated drain b returns to the deaerator 7.

[0030] The heating heat source of the tertiary heater 123 comes from the extraction steam of the steam drum 2. The generated drain is transported to the refuse pit heater 14 to further exchange heat with the refuse. The condensed water c after heat exchange is mixed with the condensate water at the outlet of the low-pressure heater 6 through a pipeline and then sent to the deaerator 7. Since the drain after heat exchange by the tertiary heater 123 with the extraction steam of the steam drum 2 is generally in a wet steam state and still has a relatively high temperature, it is selected to first enter the refuse pit heat exchanger 14 to heat the refuse and then be mixed with the condensate water at the outlet of the low-pressure heater 6 and sent to the deaerator 7. This not only promotes the fermentation of the refuse, ensures the full combustion of the refuse in the incinerator boiler, but also avoids the boiling phenomenon of the deaerator caused by the direct entry of the high-temperature drain into the deaerator, reduces the deaeration effect, and at the same time realizes the cascade utilization of energy.

[0031] In this method, the primary air first uses the waste heat of the waste power station to be preheated and raise the temperature in the primary heater 121, and then successively enters the secondary heater 122 and the tertiary heater 123 to be heated by the first-stage extraction steam a of the steam turbine 3 and the extraction steam of the steam drum 2, and finally is sent to the waste incinerator boiler 1 to assist in combustion. Compared with the primary air directly being heated by the secondary heater 122 and the tertiary heater 123, it effectively reduces the steam consumption of the first-stage extraction steam of the steam turbine and the extraction steam of the steam drum, enables more steam to enter the steam turbine to do work, increases the work done by the steam turbine, and improves the overall efficiency of the generating unit.

[0032] In addition, specifically, the hot fluid of the flue gas heat exchanger 9 is the flue gas at the outlet of the dust collector 8. When the high-temperature heat medium water at the hot water side outlet of the absorption heat pump 13 is used as the heating heat source of the primary heater 121, the cooling water at the high-temperature heat source outlet of the absorption heat pump 13 is boosted by the first circulating water pump 15 and used as the cold fluid of the flue gas heat exchanger 9; when the high-temperature circulating water at the outlet of the flue gas heat exchanger 9 is used as the heating heat source of the primary heater 121, the drain of the primary heater 121 is boosted by the first circulating water pump 15 and used as the cold fluid of the flue gas heat exchanger 9.

[0033] A part of the circulating water at the outlet of the condenser 5 enters the low-temperature heat source inlet of the absorption heat pump 13 through the seventh electric valve 23, and a part directly enters the mechanical draft cooling tower 11 for cooling; the cooling water at the low-temperature outlet of the absorption heat pump 13 is mixed with the circulating water cooled by the mechanical draft cooling tower 11 through the second circulating water pump 16 and the eighth electric valve 24 and then enters the condenser 5 to cool the exhaust steam of the steam turbine.

[0034] To implement the above method, the present embodiment also provides a system for three-stage air preheating using waste heat from a garbage power plant, comprising: a garbage incineration boiler 1, a dust collector 8, a flue gas heat exchanger 9, a chimney 10, a steam turbine 3, a generator 4, a condenser 5, a low-pressure heater 6, and a deaerator 7. The garbage incineration boiler 1, the dust collector 8, the flue gas heat exchanger 9, and the chimney 10 are connected in sequence, and the flue gas generated by the garbage incineration boiler 1 is eventually discharged into the atmosphere through the chimney 10; the steam turbine 3, the condenser 5, the low-pressure heater 6, and the deaerator 7 are connected in sequence, and the high-pressure and high-temperature steam from the garbage incineration boiler 1 enters the steam turbine 3 to work, driving the generator 4, and the exhaust steam of the steam turbine after work is cooled into condensed water in the condenser 5, flows through the low-pressure heater 6 for heating, and is sent to the garbage incineration boiler 1 through the deaerator 7.

[0035] It also includes a three-stage air preheater 12, a garbage pit heat exchanger 14, an absorption heat pump 13, and a steam drum 2. The condenser 5 is connected to the absorption heat pump 13; the three-stage air preheater 12 includes a primary heater 121, a secondary heater 122, and a tertiary heater 123 connected in sequence; the primary heater 121 is respectively connected to the flue gas heat exchanger 9 and the absorption heat pump 13; the secondary heater 122 is respectively connected to the steam turbine 3 and the deaerator 7; the tertiary heater 123 is respectively connected to the steam drum 2 and the garbage pit heat exchanger 14.

[0036] Among them, the first electric valve 17 and the sixth electric valve 22 are installed between the first-stage heater 121 and the flue gas heat exchanger 9; the third electric valve 19 and the fourth electric valve 20 are installed between the first-stage heater 121 and the absorption heat 13; the second electric valve 18 and the fifth electric valve 21 are installed between the flue gas heat exchanger 9 and the absorption heat pump 13; the seventh electric valve 23 and the eighth electric valve 24 are installed between the absorption heat pump 13 and the condenser 5.

[0037] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the protection scope of the claims of the present invention.

Claims

1. A method for three - stage air preheating using the waste heat of a waste power station, characterized in that, It includes the following steps: The primary air is heated successively by a primary heater (121), a secondary heater (122) and a tertiary heater (123) and then sent to the waste incineration boiler (1) for auxiliary combustion; Among them, the heating heat source of the primary heater (121) is selected from the high-temperature circulating water at the outlet of the flue gas heat exchanger (9) or the high-temperature heat medium water at the outlet of the hot water side of the absorption heat pump (13) according to the different temperatures of the circulating water at the outlet of the condenser (5); The heating heat source of the secondary heater (122) comes from the first-stage extraction steam a of the steam turbine (3); The heating heat source of the tertiary heater (123) comes from the extraction steam of the steam drum (2); According to the different temperatures of the circulating water at the outlet of the condenser (5), by switching the first electric valve (17), the second electric valve (18), the third electric valve (19), the fourth electric valve (20), the fifth electric valve (21), the sixth electric valve (22), the seventh electric valve (23) and the eighth electric valve (24), and at the same time adjusting the working mode of the absorption heat pump (13), the heating heat source of the primary heater (121) in the tertiary air preheater (12) is changed; When the temperature of the circulating water at the outlet of the condenser (5) is greater than or equal to the preset temperature, the first electric valve (17) and the sixth electric valve (22) are closed, and the second electric valve (18), the third electric valve (19), the fourth electric valve (20), the fifth electric valve (21), the seventh electric valve (23) and the eighth electric valve (24) are opened, so that the high-temperature circulating water at the outlet of the flue gas heat exchanger (9) serves as the high-temperature heat source of the absorption heat pump (13), a part of the circulating water at the outlet of the condenser (5) serves as the low-temperature heat source of the absorption heat pump (13), the absorption heat pump (13) starts to work, and the high-temperature heat medium water generated at the outlet of the hot water side enters the primary heater (121) as a heat source to heat the primary air, and the heated drain water returns to the inlet of the hot water side of the absorption heat pump (13); When the temperature of the circulating water at the outlet of the condenser (5) is less than the preset temperature, the first electric valve (17) and the sixth electric valve (22) are opened, the second electric valve (18), the third electric valve (19), the fourth electric valve (20), the fifth electric valve (21), the seventh electric valve (23) and the eighth electric valve (24) are closed, the absorption heat pump (13) stops working, the high-temperature circulating water at the outlet of the flue gas heat exchanger (9) serves as a heat source and directly enters the primary heater (121) to heat the primary air, and the heated drain water returns to the inlet of the flue gas heat exchanger (9) through the first circulating water pump (15); 2. A method for three - stage air preheating using the waste heat of a waste power station according to claim 1, characterized in that, The hot fluid of the flue gas heat exchanger (9) is the flue gas at the outlet of the dust collector (8). When the high-temperature heat medium water at the outlet of the hot water side of the absorption heat pump (13) serves as the heating heat source of the primary heater (121), the cooling water at the high-temperature heat source outlet of the absorption heat pump (13) is boosted by the first circulating water pump (15) and serves as the cold fluid of the flue gas heat exchanger (9); When the high-temperature circulating water at the outlet of the flue gas heat exchanger (9) serves as the heating heat source of the primary heater (121), the drain water of the primary heater (121) is boosted by the first circulating water pump (15) and then serves as the cold fluid of the flue gas heat exchanger (9).

3. A method for three-stage air preheating using the waste heat of a waste power station according to claim 1, characterized in that, A part of the circulating water at the outlet of the condenser (5) enters the low-temperature heat source inlet of the absorption heat pump (13) through the seventh electric valve (23), and a part directly enters the mechanical draft cooling tower (11) for cooling; the cooling water at the low-temperature outlet of the absorption heat pump (13) is mixed with the circulating water cooled by the mechanical draft cooling tower (11) through the second circulating water pump (16) and the eighth electric valve (24) and then enters the condenser (5) to cool the exhaust steam of the steam turbine (3).

4. A method for three - stage air preheating using the waste heat of a waste power station according to claim 1, characterized in that, The drain water of the steam extraction from the steam drum (2) after heat exchange in the tertiary heater (123) is transported to the refuse pit heat exchanger (14) to further exchange heat with the refuse, and the condensed water c after heat exchange is mixed with the condensed water at the outlet of the low-pressure heater (6) through a pipeline and then sent to the deaerator (7).

5. A method for three-stage air preheating using the waste heat of a waste power station according to claim 1, characterized in that, The drain water b of the first-stage steam extraction a of the steam turbine (3) after heat exchange in the secondary heater (122) returns to the deaerator (7).

6. A system for three-stage air preheating using the waste heat of a waste power station, the system being used to implement the method for three-stage air preheating using the waste heat of a waste power station according to any one of claims 1-5, characterized in that, Including: A tertiary air preheater (12), a flue gas heat exchanger (9), an absorption heat pump (13), a deaerator (7), a steam turbine (3), a steam drum (2), a deaerator (7) and a condenser (5), and the condenser (5) is connected to the absorption heat pump (13); The tertiary air preheater (12) includes a primary heater (121), a secondary heater (122) and a tertiary heater (123) connected in sequence; The primary heater (121) is respectively connected to the flue gas heat exchanger (9) and the absorption heat pump (13); The secondary heater (122) is respectively connected to the steam turbine (3) and the deaerator (7); The tertiary heater (123) is connected to the steam drum (2).

7. A system for three - stage air preheating using the waste heat of a waste power station according to claim 6, characterized in that, It further includes a refuse pit heat exchanger (14), and the tertiary heater (123) is connected to the refuse pit heat exchanger (14).

8. A system for three - stage air preheating using the waste heat of a waste power station according to claim 6, characterized in that, A first electric valve (17) and a sixth electric valve (22) are installed between the primary heater (121) and the flue gas heat exchanger (9); A third electric valve (19) and a fourth electric valve (20) are installed between the primary heater (121) and the absorption heat pump (13); A second electric valve (18) and a fifth electric valve (21) are installed between the flue gas heat exchanger (9) and the absorption heat pump (13); A seventh electric valve (23) and an eighth electric valve (24) are installed between the absorption heat pump (13) and the condenser (5).

Images