Coal-fired boiler waste heat comprehensive utilization system adapting to seasonal temperature change

Abstract

The utility model belongs to the technical field of energy conservation and emission reduction of coal-fired power generation, and particularly relates to a coal-fired boiler waste heat comprehensive utilization system adapting to seasonal temperature changes. Comprising a steam turbine and a coal-fired boiler, the system further comprises a bypass flue condensation water heat regeneration system A, a summer peak condensation water heat regeneration system B, a heat medium water air heater heat compensation system C and a winter air heater anti-freezing system D; boiler flue gas is recycled and utilized through a bypass flue condensation water heat regeneration system A and a heating medium water air heater heat compensation system C. When the air temperature is high in summer, a condensation water heat regeneration system B works at the peak in summer, the power capability of a low-pressure cylinder of a steam turbine is further improved, and coal consumption is reduced. At low temperature in winter, the winter air heater anti-freezing system D works to provide a heat source for the heat medium water air heater heat compensation system C; the flue gas waste heat utilization efficiency is improved, and the problem that flue gas waste heat cannot be fully utilized in summer and winter is solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of energy conservation and emission reduction of coal-fired power generation, and specifically provides a comprehensive utilization system of waste heat from coal-fired boilers that adapts to seasonal temperature changes. Background Art

[0002] Boiler exhaust heat loss is the main heat loss in coal-fired power plants, accounting for nearly 6% of the total fuel heat. Against the backdrop of continuously reducing the energy consumption of thermal power units, how to efficiently, fully and safely utilize this part of waste heat has become a hot research direction.

[0003] Although the field of flue gas waste heat utilization has developed rapidly in recent years, some key technical difficulties still exist. For example, the energy-saving potential during the peak period of summer in the process of flue gas waste heat utilization has not been deeply explored. Under the current situation that thermal power units normally operate at low load in winter, the heat exchanger equipment is at risk of low-temperature corrosion and freezing during operation.

[0004] In view of the above key difficulties, a number of key technologies have been developed with a problem-oriented approach to solve the difficulties in the utilization of flue gas waste heat. Utility Model Content

[0005] The utility model overcomes the shortcomings of the existing technology and proposes a comprehensive utilization system of waste heat from coal-fired boilers that adapts to seasonal temperature changes. The utility model is achieved through the following technical solutions:

[0006] A comprehensive utilization system for waste heat from a coal-fired boiler that adapts to seasonal temperature changes includes a steam turbine and a coal-fired boiler, wherein the steam turbine is connected to a third low-pressure heater; the system also includes a bypass flue condensate heat recovery system A, a summer peak condensate heat recovery system B, a heat transfer water heater supplementary heat system C, and a winter heater antifreeze system D; the bypass flue condensate heat recovery system A includes a condensate heat exchanger; the summer peak condensate heat recovery system B includes a heat transfer water condensate heat exchanger; the heat transfer water heater supplementary heat system C includes a heat transfer water flue gas heat exchanger and a primary and secondary air series heater; and the winter heater antifreeze system D includes a heat transfer water vapor heat exchanger;

[0007] The flue of the coal-fired boiler is connected to the condensate heat exchanger and the heat medium water flue gas heat exchanger respectively; the water inlet side of the condensate heat exchanger is connected to the water outlet side of the third low-pressure heater and the condensate side of the inlet of the third low-pressure heater respectively, and the outlet side of the condensate heat exchanger is connected to the coal-fired boiler; the heat medium water flue gas heat exchanger is connected to the primary and secondary air series heater; the water outlet side of the primary and secondary air series heater is connected to the water inlet side of the heat medium water flue gas heat exchanger through a heat medium water circulation pump; the hot air outlet of the primary and secondary air series heater is connected to the coal-fired boiler;

[0008] The hot air outlet of the primary and secondary air series heaters is connected to the heat medium water condensate heat exchanger, the condensate inlet of the heat medium water condensate heat exchanger is connected to the inlet of the third low-pressure heater; the water outlet of the heat medium water condensate heat exchanger is connected to the outlet of the third low-pressure heater;

[0009] The heat medium water vapor heat exchanger is connected to the heat medium water circulation pump; the heat medium water vapor heat exchanger is connected to other steam equipment through an auxiliary steam pipeline; other steam equipment provides auxiliary steam for the heat medium water vapor heat exchanger; the water inlet side of the heat medium water vapor heat exchanger is connected to the water outlet side of the primary and secondary air series heaters.

[0010] Furthermore, the steam turbine is connected to a first low-pressure heater and a second low-pressure heater; the third low-pressure heater is connected to a shaft seal heater; the first low-pressure heater, the second low-pressure heater and the third low-pressure heater are connected in series in sequence, the first low-pressure heater is connected to a deaerator, and the deaerator is connected to a coal-fired boiler; the outlet of the condensate heat exchanger is connected to the outlet of the first low-pressure heater.

[0011] Furthermore, the inlet of the condensate heat exchanger is connected to the first condensate booster pump, and the water flow of the condensate heat exchanger is controlled by the frequency converter of the first condensate booster pump, and the outlet water temperature of the condensate heat exchanger is automatically adjusted to be consistent with the outlet condensate temperature of the first low-pressure heater.

[0012] Furthermore, a cooling water regulating valve is provided at the inlet of the third low-pressure heater, and the condensate outlet of the shaft seal heater is connected to the cooling water regulating valve.

[0013] Furthermore, the heat transfer water heater heating system C includes a constant pressure expansion water tank, which is connected to the heat transfer water circulation pump through a pipeline.

[0014] Furthermore, a second condensate booster pump is provided at the condensate inlet of the heat medium water condensate heat exchanger; the second condensate booster pump inverter automatically controls the condensate at the outlet of the heat medium water condensate heat exchanger to be consistent with the condensate at the outlet of the third low-pressure heater.

[0015] Furthermore, the heat medium water vapor heat exchanger is connected to a drain regulating valve.

[0016] Furthermore, a bypass regulating valve is provided on the heat medium water-flue gas heat exchanger.

[0017] A method for comprehensive utilization of waste heat from a coal-fired boiler that adapts to seasonal temperature changes, based on the aforementioned system for comprehensive utilization of waste heat from a coal-fired boiler that adapts to seasonal temperature changes;

[0018] The flue of the coal-fired boiler provides hot flue gas to the condensate heat exchanger and the heat medium water flue gas heat exchanger respectively;

[0019] The inlet of the condensate heat exchanger is connected to the first condensate booster pump. The water flow of the condensate heat exchanger is controlled by the frequency converter of the first condensate booster pump, and the outlet water temperature of the condensate heat exchanger is automatically adjusted to be consistent with the condensate temperature of the first low-pressure heater outlet. The condensate heat exchanger uses the waste heat of the flue gas to heat the water extracted from the third low-pressure heater, reducing the steam extraction of the low-pressure cylinders of the steam turbine. At the same time, the condensate discharged from the condensate heat exchanger is diverted to the main condensate flow of the first and second low-pressure heaters, replacing the steam extraction of the first and second low-pressure heaters, increasing the working capacity of the low-pressure cylinders of the steam turbine and reducing coal consumption.

[0020] The waste heat of flue gas is recovered through the heat medium water flue gas heat exchanger, and dissipated to the primary and secondary air through the primary and secondary air series heaters; the primary and secondary air are sent to the coal-fired boiler for utilization; the low-temperature condensed water from the primary and secondary air series heaters enters the heat medium water flue gas heat exchanger for further heat exchange with the waste heat of flue gas;

[0021] In summer, when the unit is under high load and the ambient temperature is >25°C, the outlet temperature of the primary and secondary air series heaters is >60°C. At this time, the summer peak condensate heat recovery system B operates, and the excess hot air from the primary and secondary air series heaters enters the heat transfer water condensate heat exchanger, where it exchanges heat with the low-temperature condensate from the third low-pressure heater extracted from the heat transfer water condensate heat exchanger, recovering the excess heat to the condensate heat exchanger. The heat transfer water condensate heat exchanger displaces the steam extraction from the third low-pressure heater to the turbine, further increasing the work done by the turbine's low-pressure cylinder and reducing coal consumption.

[0022] In the low temperature environment in winter, the return water temperature of the primary and secondary air series heater outlet is less than 30℃, the winter heater antifreeze system D works, and the heat medium water vapor heat exchanger is connected to other steam equipment through the auxiliary steam pipeline; other steam equipment provides auxiliary steam for the heat medium water vapor heat exchanger; the heat medium water vapor heat exchanger supplements heat to the heat medium water flue gas heat exchanger.

[0023] Furthermore, the desuperheating water regulating valve automatically controls the inlet temperature of the first condensate booster pump to a constant 70°C; the heat medium water circulation pump adjusts the flow of the heat medium water flue gas heat exchanger and automatically controls the outlet temperature of the heat medium water flue gas heat exchanger to a constant 85°C;

[0024] The heat medium water vapor heat exchanger is connected with a drain regulating valve; the heat medium water flue gas heat exchanger is provided with a bypass regulating valve; the drain regulating valve of the heat medium water vapor heat exchanger automatically controls the outlet water temperature to ≮72°C, and at the same time, the bypass regulating valve of the heat medium water flue gas heat exchanger is automatically closed, and all the water of the heat medium water flue gas heat exchanger enters the primary and secondary air series heaters to prevent the heat exchange modules of the primary and secondary air series heaters from freezing.

[0025] The beneficial effects of the present invention compared to the prior art are as follows:

[0026] The utility model fully recycles and utilizes the excess heat during the peak operation period in summer, improves the heat utilization efficiency of the flue gas, and solves the problem that the residual heat of the flue gas at the tail of the boiler cannot be fully utilized during the peak operation of the unit in summer.

[0027] Solve the problem of low-temperature corrosion and freezing of the cold end of the deep-turn heat exchanger of the unit in winter, and ensure the safety and economy of the operation of the flue gas waste heat utilization system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a connection diagram of the bypass flue condensate heat recovery system A and the summer peak condensate heat recovery system B in the coal-fired boiler waste heat comprehensive utilization system adapted to seasonal temperature changes described in the utility model;

[0029] Figure 2 This is a schematic diagram showing the connection between the heat medium water heater supplementary heating system C and the winter heater antifreeze system D in the coal-fired boiler waste heat comprehensive utilization system adapted to seasonal temperature changes described in the present invention;

[0030] In the figure: 1 is the condensate heat exchanger, 2 is the first condensate booster pump, 3 is the first low-pressure heater, 4 is the second low-pressure heater, 5 is the third low-pressure heater, 6 is the heat medium water condensate heat exchanger, 7 is the deaerator, 8 is the attemperation water regulating valve, 9 is the shaft seal heater, 10 is the second condensate booster pump, 11 is the heat medium water flue gas heat exchanger, 12 is the primary and secondary air series heater, 13 is the constant pressure expansion water tank, 14 is the heat medium water circulation pump, 15 is the bypass regulating valve, 16 is the heat medium water vapor heat exchanger, and 17 is the drain regulating valve. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions, and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. The technical solutions of the present invention will be described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0032] See also Figure 1 and Figure 2 This embodiment proposes a comprehensive utilization system and method for waste heat from a coal-fired boiler that adapts to seasonal temperature changes. The comprehensive utilization system for waste heat from a coal-fired boiler includes a steam turbine, a bypass flue condensate heat recovery system A, a summer peak condensate heat recovery system B, a heat transfer water heater supplementary heating system C, and a winter heater antifreeze system D.

[0033] The bypass flue condensate heat recovery system A includes a condensate heat exchanger 1 and a first condensate booster pump 2;

[0034] The summer peak condensate heat recovery system B includes a heat medium water condensate heat exchanger 6 and a second condensate booster pump 10;

[0035] The heat medium water heater supplementary heating system C includes a heat medium water smoke heat exchanger 11 and a primary and secondary air series heater 12;

[0036] The winter heater antifreeze system D includes a heat medium water vapor heat exchanger 16 and a drain regulating valve 17 .

[0037] Specifically, the steam turbine is connected to a first low-pressure heater 3, a second low-pressure heater 4, and a third low-pressure heater 5; the third low-pressure heater 5 is connected to a shaft seal heater 9; the first low-pressure heater 3, the second low-pressure heater 4, and the third low-pressure heater 5 are connected in series, with the first low-pressure heater 3 connected to a deaerator 7, which is in turn connected to a coal-fired boiler. The downstream side of the air preheater bypass flue is connected to the condensate heat exchanger 1 of the bypass flue condensate heat recovery system A and the heat medium water flue gas heat exchanger 11 of the heat medium water heater supplementary heat system C, respectively, providing hot flue gas to the condensate heat exchanger 1 and the heat medium water flue gas heat exchanger 11, respectively. This creates a two-way hot flue gas recovery route under normal temperature conditions.

[0038] 1. Hot flue gas recovery route under normal temperature environment

[0039] The inlet of condensate heat exchanger 1 is connected to the first condensate booster pump 2, and the outlet of condensate heat exchanger 1 is connected to the outlet of the first low-pressure heater 3. The frequency converter of the first condensate booster pump 2 controls the water flow of condensate heat exchanger 1, automatically adjusting the outlet water temperature of condensate heat exchanger 1 to match the outlet condensate temperature of the first low-pressure heater 3. The frequency converter setting value of the first condensate booster pump 2 is: the outlet condensate temperature of the first low-pressure heater 3 + the operator's manual offset (±20°C).

[0040] The inlet water to the condensate heat exchanger 1 is a mixture of condensate from the outlet and inlet of the third low-pressure heater 5. The outlet of the third low-pressure heater 5 serves as the main water supply, while the inlet of the third low-pressure heater 5 serves as desuperheated water. A desuperheated water regulating valve 8 is installed at the inlet of the third low-pressure heater 5 to automatically control the inlet water temperature of the condensate heat exchanger 1 to a constant 70°C. The condensate heat exchanger 1 uses the waste heat of the flue gas to heat the water extracted from the third low-pressure heater 5, thereby reducing the steam extraction from the low-pressure cylinders of the steam turbine. At the same time, the condensate discharged from the condensate heat exchanger 1 is diverted to the main condensate flow of the first and second low-pressure heaters 3 and 4, thereby displacing the steam extraction from the first and second low-pressure heaters 3 and 4, increasing the working capacity of the low-pressure cylinders of the steam turbine and reducing coal consumption.

[0041] The outlet water of the first low-pressure heater 3, the second low-pressure heater 4 and the condensate heat exchanger 1 enters the deaerator 7 and is then sent to the coal-fired boiler for utilization.

[0042] Control strategy of the condensate temperature regulating valve 8 at the inlet of the condensate heat exchanger 1:

[0043] The condensate from the shaft seal heater 9 flows to the attemperating water regulating valve 8 of the first condensate booster pump 2, which regulates the inlet temperature of the first condensate booster pump 2 to a constant 70°C. The mainstream condensate at the inlet of the condensate heat exchanger 1 is taken from the outlet of the third low-pressure heater 5. The attemperating water is the condensate at the inlet of the third low-pressure heater 5. The attemperating water regulating valve 8 automatically controls the inlet temperature of the first condensate booster pump 2 to a constant 70°C to prevent low-temperature corrosion at the cold end of the condensate heat exchanger 1. The attemperating water regulating valve 8 is adjusted to maintain the setpoint temperature of 70°C at the inlet of the first condensate booster pump 2, connecting the inlet of the third low-pressure heater 5 to the main inlet pipe of the first condensate booster pump 2.

[0044] 2. Hot flue gas recovery route 2 under normal temperature environment

[0045] In the heat transfer water heater supplementary heating system C, the heat transfer water flue gas heat exchanger 11 is connected to the primary and secondary air series heater 12. The heat transfer water flue gas heat exchanger 11 recovers waste heat from the flue gas, which is then countercurrently exchanged with the exhaust gas from the air preheater. The absorbed heat is then dissipated to the primary and secondary air series heater 12, forming a closed loop on the water side. The primary and secondary air are then fed into the coal-fired boiler for utilization.

[0046] Specifically, the heat transfer water heater reheating system C also includes two heat transfer water circulation pumps 14. The water outlets of the primary and secondary air series heaters 12 are connected to the water inlet of the heat transfer water flue gas heat exchanger 11 via the heat transfer water circulation pumps 14. Low-temperature condensate from the primary and secondary air series heaters 12 enters the heat transfer water flue gas heat exchanger 11 for further heat exchange with the flue gas waste heat. The heat transfer water heater reheating system C is equipped with a constant-pressure expansion tank 13, which automatically replenishes the water with condensate to maintain pressure.

[0047] The design ambient temperature is 25°C. The heat transfer water at the outlet of heat transfer water flue gas heat exchanger 11 is at 90°C. This high-temperature heat transfer water enters primary and secondary air series heater 12, heating the primary and secondary air to 60°C. The water at the outlet of primary and secondary air series heater 12 returns to the inlet of heat transfer water circulation pump 14, forming a closed loop. A bypass regulating valve 15 is installed at heat transfer water flue gas heat exchanger 11 to automatically control the inlet water temperature of the circulating water pump to 70°C. The design flue gas temperature at the inlet of heat transfer water flue gas heat exchanger 11 is 115°C, and the outlet flue gas temperature drops to 85°C before being discharged into the desulfurization tower.

[0048] Heat medium water circulation pump 14 inverter control strategy:

[0049] The water-heating flue gas heat exchanger 11, along with the primary and secondary air series heater 12, forms the water-heating air heater supplemental heating system C. Two water-heating circulation pumps 14 are configured to regulate the flow through the water-heating flue gas heat exchanger 11 and automatically control the flue gas outlet temperature at a constant 85°C. The variable speed drive on the water-heating flue gas heat exchanger 14 controls the flue gas outlet temperature (the median of three).

[0050] Control strategy of the bypass regulating valve 15 at the outlet of the heat medium water flue gas heat exchanger 11:

[0051] Automatically control the water temperature at the inlet of the heat transfer water circulation pump 14 to 70°C to prevent low-temperature corrosion at the cold end of the flue gas cooler. The bypass regulating valve 15 at the outlet of the heat transfer water flue gas heat exchanger 11 is regulated to the water temperature at the inlet of the heat transfer water circulation pump 14, taking the middle value of the three. Setpoint: Manually set to 70±10°C.

[0052] Through the two-way hot flue gas recovery route, the waste heat of the flue gas of the coal-fired boiler can be recovered and utilized at normal ambient temperature. On the one hand, it can provide a part of hot water and hot air for the gas boiler. On the other hand, it can reduce the extraction of steam turbines, increase the working capacity of the low-pressure cylinder of the steam turbine and reduce coal consumption.

[0053] 3. Utilization of waste heat in high temperature environment in summer

[0054] During summer, when the unit is under high load and the ambient temperature exceeds 25°C, the outlet temperature of the primary and secondary air series heater 12 exceeds 60°C. At this time, the summer peak condensate reheating system B operates. The primary and secondary air series heater 12 is connected to the heat transfer water condensate heat exchanger 6. The condensate inlet of the heat transfer water condensate heat exchanger 6 is the low-temperature condensate inlet of the third low-pressure heater 5. The first condensate booster pump 2, with its variable frequency pump, automatically maintains the outlet condensate temperature at the same level as the condensate outlet of the third low-pressure heater 5. Excess hot air from the primary and secondary air series heater 12 enters the heat transfer water condensate heat exchanger 6, where it exchanges heat with the low-temperature condensate extracted from the third low-pressure heater 5, recovering the excess heat into the condensate system. The heat transfer water condensate heat exchanger 6 displaces the steam extraction from the third low-pressure heater 5 to the turbine, further increasing the work done by the turbine's low-pressure cylinders and reducing coal consumption.

[0055] A second condensate booster pump 10 is provided at the condensate inlet of the heat medium water condensate heat exchanger 6; the inverter control strategy of the second condensate booster pump 10 is:

[0056] During high summer load conditions, the unit draws condensate from the inlet of the third low-pressure heater (5). This condensate then absorbs heat through the heat transfer water-condensate heat exchanger (6). The heated condensate then returns to the outlet of the third low-pressure heater (5). The inverter in the second condensate booster pump (10) automatically controls the condensate at the outlet of the heat transfer water-condensate heat exchanger (6) to match the condensate at the outlet of the third low-pressure heater (5). This condensate displaces steam extraction from the third low-pressure heater (5), further increasing the turbine's low-pressure cylinder capacity and reducing coal consumption. The inverter in the second condensate booster pump (10) is controlled by the condensate temperature at the outlet of the heat transfer water-condensate heat exchanger (6), with a set value of the condensate temperature at the outlet of the third low-pressure heater (5).

[0057] 4. Utilization of waste heat in low temperature environment in winter

[0058] In low-temperature winter environments, the winter heater antifreeze system D operates. It includes a heat medium water vapor heat exchanger 16 and a drain control valve 17. The heat medium water vapor heat exchanger 16 is connected to the heat medium water circulation pump 14; the drain control valve 17 is also connected to the heat medium water vapor heat exchanger 16. The heat medium water vapor heat exchanger 16 is connected to other steam equipment via auxiliary steam pipelines; these other steam equipment provide auxiliary steam for the heat medium water vapor heat exchanger 16. The water inlet of the heat medium water vapor heat exchanger 16 is connected to the outlet of the primary and secondary air series heater 12.

[0059] During winter, when the return water temperature at the outlet of the primary and secondary air series heater 12 is less than 30°C, it is fed into the heat medium water vapor heat exchanger 16 at the heater's outlet to replenish heat for the heat medium water system. The drain regulating valve 17 of the heat medium water vapor heat exchanger 16 automatically controls the outlet water temperature to ≤ 72°C. Simultaneously, the bypass regulating valve 15 of the heat medium water and flue gas heat exchanger 11 automatically closes, allowing all the water in the heat medium water and flue gas heat exchanger 11 to flow into the primary and secondary air series heater 12, preventing freezing of the heat exchange modules there.

[0060] Control strategy for heat transfer water vapor heat exchanger 16: During winter months with low temperatures and the return water temperature at the secondary air heater outlet below 30°C, heat transfer water vapor heat exchanger 16 is activated to provide supplemental heat to the heat transfer water system. Drain control valve 17 automatically controls the outlet heat transfer water temperature to ≤ 72°C. Simultaneously, bypass control valve 15 of heat transfer water flue gas heat exchanger 11 automatically closes, achieving maximum heater flow and preventing freezing of the primary and secondary air series heater 12 modules. Drain control valve 17 is regulated by the inlet water temperature of the heat transfer water circulation pump 14, taking the middle value of the three. Setpoint: Manually set to 72±10°C.

[0061] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.

Claims

1. A comprehensive utilization system of waste heat from a coal-fired boiler that adapts to seasonal temperature changes, comprising a steam turbine and a coal-fired boiler, wherein the steam turbine is connected to a third low-pressure heater (5); characterized in that: It also includes a bypass flue condensate heat recovery system A, a summer peak condensate heat recovery system B, a heat transfer water heater heating system C, and a winter heater antifreeze system D; the bypass flue condensate heat recovery system A includes a condensate heat exchanger (1); the summer peak condensate heat recovery system B includes a heat transfer water condensate heat exchanger (6); the heat transfer water heater heating system C includes a heat transfer water flue gas heat exchanger (11) and a primary and secondary air series heater (12); the winter heater antifreeze system D includes a heat transfer water vapor heat exchanger (16); The flue of the coal-fired boiler is respectively connected to the condensate heat exchanger (1) and the heat medium water flue gas heat exchanger (11); the water inlet side of the condensate heat exchanger (1) is respectively connected to the water outlet side of the third low-pressure heater (5) and the condensate side of the inlet of the third low-pressure heater (5), and the outlet side of the condensate heat exchanger (1) is connected to the coal-fired boiler; the heat medium water flue gas heat exchanger (11) is connected to the primary and secondary air series heater (12); the water outlet side of the primary and secondary air series heater (12) is connected to the water inlet side of the heat medium water flue gas heat exchanger (11) through the heat medium water circulation pump (14); the hot air outlet of the primary and secondary air series heater (12) is connected to the coal-fired boiler; The hot air outlet of the primary and secondary air series heater (12) is connected to the heat medium water condensate heat exchanger (6), and the condensate inlet of the heat medium water condensate heat exchanger (6) is connected to the inlet of the third low-pressure heater (5); the water outlet of the heat medium water condensate heat exchanger (6) is connected to the outlet of the third low-pressure heater (5); The heat medium water vapor heat exchanger (16) is connected to the heat medium water circulation pump (14); the heat medium water vapor heat exchanger (16) is connected to other steam equipment through an auxiliary steam pipeline; the water inlet side of the heat medium water vapor heat exchanger (16) is connected to the water outlet side of the primary and secondary air series heater (12).

2. The comprehensive utilization system of waste heat from coal-fired boilers that adapts to seasonal temperature changes according to claim 1 is characterized in that: The steam turbine is connected to a first low-pressure heater (3) and a second low-pressure heater (4); the third low-pressure heater (5) is connected to a shaft seal heater (9); the first low-pressure heater (3), the second low-pressure heater (4) and the third low-pressure heater (5) are connected in series, the first low-pressure heater (3) is connected to a deaerator (7), and the deaerator (7) is connected to a coal-fired boiler; the water outlet of the condensate heat exchanger (1) is connected to the water outlet of the first low-pressure heater (3).

3. The comprehensive utilization system of waste heat from coal-fired boilers that adapts to seasonal temperature changes according to claim 2 is characterized in that: The inlet of the condensate heat exchanger (1) is connected to the first condensate booster pump (2).

4. The comprehensive utilization system of waste heat from coal-fired boilers adapting to seasonal temperature changes according to claim 3 is characterized in that: A cooling water regulating valve (8) is provided at the inlet of the third low-pressure heater (5), and the condensate outlet of the shaft seal heater (9) is connected to the cooling water regulating valve (8).

5. The comprehensive utilization system of waste heat from coal-fired boilers adapting to seasonal temperature changes according to claim 1 is characterized in that: The heat transfer water heater heating system C comprises a constant pressure expansion water tank (13), which is connected to a heat transfer water circulation pump (14) via a pipeline.

6. The comprehensive utilization system of waste heat from coal-fired boilers adapting to seasonal temperature changes according to claim 1 is characterized in that: A second condensate booster pump (10) is provided at the condensate inlet of the heat medium water condensate heat exchanger (6).

7. The comprehensive utilization system of waste heat from coal-fired boilers adapting to seasonal temperature changes according to claim 1 is characterized in that: The heat medium water vapor heat exchanger (16) is connected to a drain regulating valve (17).

8. The comprehensive utilization system of waste heat from coal-fired boilers adapting to seasonal temperature changes according to claim 1 is characterized in that: The heat medium water flue gas heat exchanger (11) is provided with a bypass regulating valve (15).

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