A new energy storage type dry spike cooling system

Abstract

The present application relates to the technical field of coal-fired unit energy saving and consumption reduction, and particularly relates to a novel energy storage type dry peak cooling system, which comprises a peak condenser, a dry air cooling tower, a water storage pool, a water storage pool circulating pump, a cooling tower circulating pump and a DCS control center, wherein the DCS control center receives the exhaust steam pressure data of the steam turbine monitored by a pressure sensor in real time, compares the data with a built-in back pressure threshold value, and issues corresponding instructions according to the comparison result. Based on the design concept of energy storage, the capacity requirement of the dry air cooling tower is reduced by reasonably allocating and storing the cooling water resources, and the problem of limited space in the plant is solved. Meanwhile, by adopting the mixed cooling mode of dry air cooling tower cold water and water storage pool cold water, the temperature of the peak condenser is effectively reduced, thereby the back pressure of the unit is reduced, the load carrying capacity of the unit is improved, the unit can be stably operated at the rated output during the high temperature period in summer, and the problem of high back pressure and limited load of the original direct air cooling system in summer is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal-fired unit energy saving and consumption reduction, and particularly relates to a novel energy storage type dry peak cooling system. BACKGROUND

[0002] The direct air-cooling unit is widely used in the "three northern regions" of China which are rich in coal and lack of water. The direct air-cooling system generally comprises a steam exhaust device, a steam exhaust pipeline, a parallel-flow radiator pipe bundle, a counter-flow radiator pipe bundle, an axial-flow fan, a condensate water system, a vacuum pumping system and a cleaning system. At present, the use proportion of the parallel-flow and counter-flow radiator pipe bundles of the direct air-cooling unit in China is as follows: for single-row pipes, the counter-flow proportion is about 20%; for double-row pipes, the counter-flow proportion is about 20-30%; for three-row pipes, the counter-flow proportion is about 15-30%; and for special air temperature conditions, the counter-flow proportion can be changed. In recent years, the pipe bundle structure of the condenser is mostly single-row pipes.

[0003] Compared with the conventional cooling system of the wet cooling tower, the cooling capacity of the air cooling system of the direct air-cooling unit is more affected by the environmental factors and is more sensitive to the changes of the environmental temperature and natural wind. When the direct air-cooling unit is designed, the economic relationship between the heat dissipation area of the air cooling radiator and the full-load hours of the hottest air temperature in a year is considered. The heat exchange end difference of the early-produced air-cooling unit is large, and the actual operation back pressure of the unit is far higher than the design characteristics due to the influences of the increased heat consumption of the unit, the dirt pollution of the heat dissipation surface and the hot air recirculation and other factors. The steam turbine exhaust back pressure is high during the high-temperature period in summer, and the unit cannot be operated at full load.

[0004] The traditional peak cooling system mostly adopts the direct air-cooling system capacity expansion or the newly-added wet peak system. The direct air-cooling system capacity expansion has high requirements for the plant space, long construction period and great difficulty, especially in the connection mode of the new and old steel structure platforms and the safety hazards during the operation of the old platform fan during the construction of the new platform. Therefore, the engineering application of this mode is less in China. The newly-added wet peak system is mostly used at present, but the application of this mode is limited in the power plant with high water consumption requirements.

[0005] Therefore, it is urgent to develop a peak cooling system to solve the problem of the difficulty of the air-cooling system capacity expansion of the power plant in the water shortage area and the power plant with limited plant space. SUMMARY

[0006] In view of the above problems in the prior art, the present application provides a novel energy storage type dry peak cooling system to solve the problem of the difficulty of the air-cooling system capacity expansion of the power plant in the water shortage area and the power plant with limited plant space.

[0007] The present application is based on the design concept of energy storage, greatly reduces the capacity demand of the dry air cooling tower by reasonably allocating and storing cooling water resources, solves the problem of limited space in the plant; at the same time, by adopting the mixed cooling mode of dry air cooling tower cold water and water storage pool cold water, the temperature of the peak condenser is effectively reduced, thereby reducing the back pressure of the unit and improving the load carrying capacity of the unit, so that the unit can stably operate at the rated output during the high temperature period in summer, realizing efficient management of the direct air cooling system, solving the problem of high back pressure and limited load of the original direct air cooling system in summer. In addition, the present application also sets two working modes, and switches the cooling mode flexibly under different working conditions to realize the demand under different working modes, and meets the dual goals of efficient operation and environmental protection and energy saving.

[0008] The present application provides a novel energy storage type dry peak cooling system, comprising: a peak condenser, a dry air cooling tower, a water storage pool, a water storage pool circulating pump, a cooling tower circulating pump and a DCS control center, wherein the peak condenser is connected with the exhaust pipe, the peak condenser, the dry air cooling tower and the water storage pool are connected through the pipeline, and the DCS control center is electrically connected with the peak condenser, the dry air cooling tower, the water storage pool circulating pump and the cooling tower circulating pump.

[0009] The connection between the peak condenser and the pipeline is provided with a first valve and a second valve, the connection between the dry air cooling tower and the pipeline is provided with a third valve and a fourth valve, the connection between the water storage pool and the pipeline is provided with a fifth valve, a sixth valve and a seventh valve, and the pipeline comprises a first pipeline, a second pipeline, a third pipeline, a fourth pipeline and a fifth pipeline.

[0010] The water storage pool circulating pump is arranged on the first pipeline on the side of the fifth valve, and the water storage pool circulating pump is provided with an eighth valve and a ninth valve at both ends; the cooling tower circulating pump is arranged on the third pipeline, and the cooling tower circulating pump is provided with a tenth valve at both ends.

[0011] The DCS control center receives the exhaust pressure data of the steam turbine, i.e. the back pressure data, in real time, compares it with the built-in back pressure threshold value, and if the back pressure data received by the DCS control center is greater than or equal to the built-in back pressure threshold value, the DCS control center runs the high back pressure working mode, otherwise the DCS control center runs the low back pressure working mode, wherein the high back pressure working mode is that the cold water of the dry air cooling tower is mixed with the cold water of the water storage pool, then the heat exchange and temperature rise of the mixed water in the peak condenser and the exhaust steam from the exhaust pipe, and then the heated water is returned to the dry air cooling tower and the water storage pool, so as to improve the heat exchange capacity of the direct air cooling system; the low back pressure working mode is that the peak condenser is out of operation, the cold water of the dry air cooling tower is transported to the water storage pool, the hot water of the water storage pool is cooled, and the hot water of the water storage pool is circulated and returned to the dry air cooling tower, so as to realize the cooling of the hot water of the water storage pool.

[0012] Preferably, the peak condenser is connected with the water storage pool through the first valve, the first pipeline and the fifth valve, and the dry air cooling tower is connected with the water storage pool through the fourth valve, the fourth pipeline and the sixth valve.

[0013] Preferably, the peak condenser is connected with the water storage pool through the first valve, the first pipeline and the fifth valve, and the dry air cooling tower is connected with the water storage pool through the fourth valve, the fourth pipeline and the sixth valve.

[0014] Preferably, the second pipeline is communicated with the first pipeline at both ends, and the seventh valve is arranged on the second pipeline.

[0015] Preferably, one end of the second pipeline is communicated with the first pipeline at one side of the fifth valve, and the other end is communicated with the first pipeline at one side of the eighth valve.

[0016] Preferably, the DCS control center is electrically connected with the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, the eighth valve, the ninth valve and the tenth valve.

[0017] Preferably, the DCS control center is further used for setting water delivery amounts of the peak condenser, the dry air cooling tower and the water storage pool according to actual demands of workers, and adjusting opening degrees of corresponding valves based on the water delivery amounts set by the workers.

[0018] Preferably, the high back pressure working mode is specifically as follows: the DCS control center controls the seventh valve to be closed and the other valves to be opened, and simultaneously controls the water storage pool circulating pump and the cooling tower circulating pump to start working; cold water of the water storage pool is delivered to the peak condenser through the first pipeline under the pressure boosting of the water storage pool circulating pump; at the same time, cold water of the dry air cooling tower is also delivered to the first pipeline through the third pipeline under the pressure boosting of the cooling tower circulating pump; the cold water from the water storage pool and the cold water from the dry air cooling tower are mixed together in the first pipeline and then delivered to the peak condenser; the steam from the exhaust pipeline exchanges heat with the peak condenser to be warmed up; then the steam is divided into two routes after entering the fourth pipeline through the fifth pipeline; one route is returned to the dry air cooling tower through the fourth valve, and the other route is returned to the water storage pool through the sixth valve; and the cycle is repeated to improve the heat exchange capacity of the direct air cooling system.

[0019] The low back pressure working mode is specifically as follows: the DCS control center controls the peak condenser, the first valve, the second valve, the water storage pool circulating pump, the eighth valve and the ninth valve to be closed, and controls the other valves to be opened; and simultaneously, the DCS control center controls the cooling tower circulating pump to start working; cold water of the dry air cooling tower is delivered to the first pipeline through the third pipeline under the pressure boosting of the cooling tower circulating pump; under the condition that the peak condenser, the first valve and the second valve are closed, the cold water is delivered to the water storage pool through the first pipeline, the seventh valve and the fifth valve; then the hot water of the water storage pool is circulated and returned to the dry air cooling tower through the sixth valve, the fourth pipeline and the fourth valve; and the cycle is repeated to realize the cooling of the hot water of the water storage pool.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] 1、The present application adopts the design concept of energy storage, by reasonably allocating and storing cooling water resources, not only greatly reduces the capacity demand of the dry air cooling tower, solves the problem of limited space in the plant, but also reduces the dependence on land resources.

[0022] 2、The present application adopts the mixed cooling mode of dry air cooling tower cold water and reservoir cold water, effectively reduces the temperature of the sharp condenser, and further reduces the back pressure of the unit, improves the load carrying capacity of the unit, so that the unit can stably operate at the rated output during the summer high temperature period, realizes the efficient management of the direct air cooling system, solves the problem of high back pressure and limited load of the original direct air cooling system in summer; In addition, the mixed cooling mode recycles the cold water in the reservoir, without additional water resource consumption, meeting the requirements of water saving and environmental protection.

[0023] 3、The present application realizes the demand in different working modes by flexible switching of the cooling mode, meets the dual goals of efficient operation of the system and environmental protection and energy saving.

[0024] 4、The present application greatly reduces the cost of transformation investment and land scale, brings significant economic benefits to the enterprise. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of the drawings.

[0026] Figure 1 A structure diagram of a new energy storage type dry sharp cooling system in the embodiment of the present application;

[0027] Figure 2 A high back pressure working mode operation flow chart in the embodiment of the present application;

[0028] Figure 3 A low back pressure working mode operation flow chart in the embodiment of the present application. DETAILED DESCRIPTION

[0029] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0030] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application; the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrated connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication between two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] As shown in Figure 1 The present application provides a new energy storage type dry peak cooling system, which comprises a peak condenser 1, a dry air cooling tower 2, a water reservoir 3, a water reservoir circulating pump 4, a cooling tower circulating pump 5 and a DCS control center, wherein the peak condenser 1 is connected with an exhaust pipe, the peak condenser 1, the dry air cooling tower 2 and the water reservoir 3 are connected through pipes, and the DCS control center is electrically connected with the peak condenser 1, the dry air cooling tower 2, the water reservoir circulating pump 4 and the cooling tower circulating pump 5.

[0032] In the present application, the connection between the peak condenser 1 and the pipe is provided with a first valve 11 and a second valve 12, the connection between the dry air cooling tower 2 and the pipe is provided with a third valve 21 and a fourth valve 22, and the connection between the water reservoir 3 and the pipe is provided with a fifth valve 31, a sixth valve 32 and a seventh valve 33.

[0033] The pipes involved in the embodiments of the present application include a first pipe 6, a second pipe 7, a third pipe 8, a fourth pipe 9 and a fifth pipe 10.

[0034] In the embodiments of the present application, the peak condenser 1 is connected with the water reservoir 3 through the first valve 11, the first pipe 6 and the fifth valve 31, and the peak condenser 1 is communicated with the fourth pipe 9 through the second valve 12 and the fifth pipe 10.

[0035] In the embodiment of the present application, the water reservoir circulating pump 4 is arranged on the first pipeline 6 at one side of the fifth valve 31, and the eighth valve 41 and the ninth valve 42 are arranged at two ends of the water reservoir circulating pump 4.

[0036] In the embodiment of the present application, the second pipeline 7 is in communication with the first pipeline 6 at two ends, and the seventh valve 33 is arranged on the second pipeline 7.

[0037] Preferably, one end of the second pipeline 7 is in communication with the first pipeline 6 at one side of the fifth valve 31, and the other end is in communication with the first pipeline 6 at one side of the eighth valve 41.

[0038] In the embodiment of the present application, the dry air cooling tower 2 is in communication with the first pipeline 6 through the third valve 21 and the third pipeline 8, and the dry air cooling tower 2 is connected with the water reservoir 3 through the fourth valve 22, the fourth pipeline 9 and the sixth valve 32.

[0039] In the embodiment of the present application, the cooling tower circulating pump 5 is arranged on the third pipeline 8, and the tenth valve 51 is arranged at two ends of the cooling tower circulating pump 5.

[0040] In the embodiment of the present application, the DCS control center is electrically connected with the first valve 11, the second valve 12, the third valve 21, the fourth valve 22, the fifth valve 31, the sixth valve 32, the seventh valve 33, the eighth valve 41, the ninth valve 42 and the tenth valve 51.

[0041] In the present application, the DCS control center receives the exhaust pressure data of the steam turbine, i.e. the back pressure data, in real time, and compares the back pressure data with the built-in back pressure threshold value. If the back pressure data received by the DCS control center is greater than or equal to the built-in back pressure threshold value, the DCS control center operates in a high back pressure mode. Otherwise, the DCS control center operates in a low back pressure mode. In the high back pressure mode, the cold water of the dry air cooling tower 2 is mixed with the cold water of the water reservoir 3, the mixed water is heated by exchanging heat with the exhaust steam from the exhaust pipeline in the peak condenser 1, and then the heated water is returned to the dry air cooling tower 2 and the water reservoir 3, so as to improve the heat exchange capacity of the direct air cooling system. In the low back pressure mode, the peak condenser 1 is out of operation, the cold water of the dry air cooling tower 2 is transported to the water reservoir 3, the hot water of the water reservoir 3 is cooled, and the hot water of the water reservoir 3 is circulated and returned to the dry air cooling tower 2, so as to realize the cooling of the hot water of the water reservoir 3.

[0042] When the system is in high load operation, the present application adopts the mixed cooling mode of the dry air cooling tower cold water and the water reservoir cold water, which effectively reduces the temperature of the peak condenser and ensures the stable operation of the system. When the system load is low, the present application lets the peak condenser out of operation, and only uses the dry air cooling tower to cool the hot water in the water reservoir, thereby further improving the energy efficiency and flexibility of the system.

[0043] If necessary, a pressure sensor is arranged on the exhaust pipe to obtain the measurement of back pressure, which is a conventional arrangement in the field, and thus will not be explained in detail.

[0044] As shown in Figure 1 , 2 , in the embodiment of the application, the high back pressure working mode is specifically:

[0045] The DCS control center controls the seventh valve 33 to be closed, and other valves to be opened, and at the same time, the DCS control center also controls the water storage pool circulating pump 4 and the cooling tower circulating pump 5 to start working. The cold water in the water storage pool 3 is transported to the peak condenser 1 through the first pipeline 6 under the pressure boosting of the water storage pool circulating pump 4, and at the same time, the cold water in the dry air cooling tower 2 is also transported to the first pipeline 6 through the third pipeline 8 under the pressure boosting of the cooling tower circulating pump 5, and after mixing with the cold water from the water storage pool 3, they are transported to the peak condenser 1 together, the peak condenser 1 exchanges heat with the exhaust steam from the exhaust pipe to be warmed up, and then enters the fourth pipeline 9 through the fifth pipeline 10 and is divided into two ways, one way returns to the dry air cooling tower 2 through the fourth valve 22, and the other way returns to the water storage pool 3 through the sixth valve 32, so as to circulate and improve the heat exchange capacity of the direct air cooling system.

[0046] As shown in Figure 1 , 3 , in the embodiment of the application, the low back pressure working mode is specifically:

[0047] The DCS control center controls the peak condenser 1, the first valve 11, the second valve 12, the water storage pool circulating pump 4, the eighth valve 41 and the ninth valve 42 to be closed, and other valves to be opened, and at the same time, the DCS control center also controls the cooling tower circulating pump 5 to start working. The cold water in the dry air cooling tower 2 is transported to the first pipeline 6 through the third pipeline 8 under the pressure boosting of the cooling tower circulating pump 5, and under the condition that the peak condenser 1, the first valve 11 and the second valve 12 are closed, it is transported to the water storage pool 3 through the first pipeline 6, the seventh valve 33 and the fifth valve 31, and then the hot water in the water storage pool 3 is circulated and returned to the dry air cooling tower 2 through the sixth valve 32, the fourth pipeline 9 and the fourth valve 22, so as to circulate and realize the temperature reduction of the hot water in the water storage pool 3.

[0048] Preferably, the DCS control center is also used for workers to set the water delivery amount of the peak condenser 1, the dry air cooling tower 2 and the water storage pool 3 according to actual needs, and to adjust the opening degree of the corresponding valve based on the water delivery amount set by the workers.

[0049] It should be noted that the water supply of the peak condenser 1, the dry air cooling tower 2 and the water storage pool 3 is set according to the actual situation; in addition, after the DCS receives the expected water supply set by the staff, it will calculate the opening degree that each valve should reach through its built-in algorithm or control strategy, and send the corresponding control signal to each valve, and after each valve receives the signal, it will adjust the opening degree accordingly, which is a regular function of DCS in industrial automation, and this application does not make specific limitations.

[0050] Example one

[0051] High back pressure working mode: the water storage pool 3 supplies 50℃ water to the peak condenser 1 at a speed of 3000t / h through the first pipeline 6 under the pressure boosting of the water storage pool circulating pump 4, at the same time, the dry air cooling tower 2 also supplies 40℃ water to the first pipeline 6 at a speed of 3000t / h through the third pipeline 8 under the pressure boosting of the cooling tower circulating pump 5, after mixing in the first pipeline 6, they start to supply 45℃ water to the peak condenser 1 at a speed of 6000t / h, after heat exchange with the exhaust steam from the exhaust pipeline, the water in the peak condenser 1 is heated to 60℃, then enters the fourth pipeline 9 through the fifth pipeline 10, and is divided into two ways, one way returns 60℃ water to the dry air cooling tower 2 through the fourth valve 22, the other way returns 60℃ water to the water storage pool 3 through the sixth valve 32, so as to circulate and improve the heat exchange capacity of the direct air cooling system.

[0052] Low back pressure working mode: the cold water of the dry air cooling tower 2 is supplied to the water storage pool 3 at a speed of 3000t / h through the third pipeline 8, the first pipeline 6, the seventh valve 33 and the fifth valve 31 under the pressure boosting of the cooling tower circulating pump 5, then the water storage pool 3 circulates the 60℃ water in the pool back to the dry air cooling tower 2 through the sixth valve 32, the fourth pipeline 9 and the fourth valve 22, so as to circulate and realize the cooling of the hot water in the water storage pool 3.

[0053] Example two

[0054] High back pressure working mode: the water storage pool 3 supplies 40℃ water to the peak condenser 1 at a speed of 4000t / h through the first pipeline 6 under the pressure boosting of the water storage pool circulating pump 4, at the same time, the dry air cooling tower 2 also supplies 55℃ water to the first pipeline 6 at a speed of 4000t / h through the third pipeline 8 under the pressure boosting of the cooling tower circulating pump 5, after mixing in the first pipeline 6, they start to supply 47.5℃ water to the peak condenser 1 at a speed of 8000t / h, after heat exchange with the exhaust steam from the exhaust pipeline, the water in the peak condenser 1 is heated to 65℃, then enters the fourth pipeline 9 through the fifth pipeline 10, and is divided into two ways, one way returns 65℃ water to the dry air cooling tower 2 through the fourth valve 22, the other way returns 65℃ water to the water storage pool 3 through the sixth valve 32, so as to circulate and improve the heat exchange capacity of the direct air cooling system.

[0055] Low back pressure mode of operation: the cold water of the dry air cooling tower 2 is pumped by the cooling tower circulating pump 5 at a speed of 4000t / h, through the third pipeline 8, the first pipeline 6, the seventh valve 33 and the fifth valve 31 to the water storage pool 3 to deliver 40℃ water, and then the water storage pool 3 circulates the 65℃ water in the pool back to the dry air cooling tower 2 through the sixth valve 32, the fourth pipeline 9 and the fourth valve 22, so as to realize the cooling of the hot water in the water storage pool 3.

[0056] Example three

[0057] High back pressure mode of operation: the water storage pool 3 is pumped by the water storage pool circulating pump 4 at a speed of 5000t / h through the first pipeline 6 to the sharp peak condenser 1 to deliver 40℃ water, and at the same time, the dry air cooling tower 2 is also pumped by the cooling tower circulating pump 5 at a speed of 5000t / h through the third pipeline 8 to the first pipeline 6 to deliver 60℃ water, and after mixing in the first pipeline 6, they start to deliver 50℃ water to the sharp peak condenser 1 at a speed of 10000t / h, and after heat exchange with the exhaust steam from the exhaust pipeline, 70℃ water is formed in the sharp peak condenser 1, and then enters the fourth pipeline 9 through the fifth pipeline 10 and is divided into two ways, one way circulates the 70℃ water back to the dry air cooling tower 2 through the fourth valve 22, and the other way circulates the 70℃ water back to the water storage pool 3 through the sixth valve 32, so as to improve the heat exchange capacity of the direct air cooling system.

[0058] Low back pressure mode of operation: the cold water of the dry air cooling tower 2 is pumped by the cooling tower circulating pump 5 at a speed of 5000t / h, through the third pipeline 8, the first pipeline 6, the seventh valve 33 and the fifth valve 31 to the water storage pool 3 to deliver 40℃ water, and then the water storage pool 3 circulates the 70℃ water in the pool back to the dry air cooling tower 2 through the sixth valve 32, the fourth pipeline 9 and the fourth valve 22, so as to realize the cooling of the hot water in the water storage pool 3.

[0059] Finally, it should be noted that the above description is only for the preferred embodiments of the present application and is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacement of some technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A novel energy storage type dry peak cooling system, characterized by, The utility model relates to a kind of direct air-cooled system, including: Peak condenser, dry air cooling tower, reservoir, reservoir circulating pump, cooling tower circulating pump and DCS control center, wherein peak condenser is connected with exhaust pipe, peak condenser, dry air cooling tower and reservoir are connected by pipeline, DCS control center is electrically connected with peak condenser, dry air cooling tower, reservoir circulating pump, cooling tower circulating pump; First valve and second valve are equipped at the connection of peak condenser and pipeline, third valve and fourth valve are equipped at the connection of dry air cooling tower and pipeline, fifth valve, sixth valve and seventh valve are equipped at the connection of reservoir and pipeline, and pipeline includes first pipeline, second pipeline, third pipeline, fourth pipeline and fifth pipeline; Reservoir circulating pump is arranged on the first pipeline at the side of fifth valve, and eighth valve and ninth valve are equipped at both ends of reservoir circulating pump;Cooling tower circulating pump is arranged on third pipeline, and tenth valve is equipped at both ends of cooling tower circulating pump; DCS control center receives the exhaust pressure data of steam turbine, i.e. back pressure data, in real time, and compares with the built-in back pressure threshold value, if the back pressure data received by DCS control center is greater than or equal to the built-in back pressure threshold value, DCS control center runs high back pressure mode, otherwise DCS control center runs low back pressure mode, wherein high back pressure mode is that the cold water of dry air cooling tower and the cold water of reservoir are mixed, then the heated water is returned to dry air cooling tower and reservoir after heat exchange and temperature rise in peak condenser and from exhaust pipe, so as to improve the heat exchange capacity of direct air-cooled system, specifically: DCS control center controls seventh valve to be closed, and other valves to be opened, and at the same time, DCS control center also controls reservoir circulating pump and cooling tower circulating pump to start working, the cold water of reservoir is transported to peak condenser through first pipeline under the pressure boosting of reservoir circulating pump, at the same time, the cold water of dry air cooling tower is also transported to first pipeline through third pipeline under the pressure boosting of cooling tower circulating pump, and the cold water from reservoir is mixed in first pipeline and transported to peak condenser together, peak condenser is heat exchanged and temperature rises with the exhaust steam from exhaust pipe, then enters fourth pipeline through fifth pipeline and is divided into two ways, one way returns to dry air cooling tower through fourth valve, the other way returns to reservoir through sixth valve, so as to improve the heat exchange capacity of direct air-cooled system; Low back pressure mode is that peak condenser exits operation, the cold water of dry air cooling tower is transported to reservoir, the hot water of reservoir is cooled, and the hot water of reservoir is circulated and returned to dry air cooling tower, so as to cool the hot water of reservoir, specifically: The DCS control center controls the peak condenser, the first valve, the second valve, the reservoir circulating pump, the eighth valve and the ninth valve to be closed, and other valves to be opened, and simultaneously controls the cooling tower circulating pump to start working. The cold water of the dry air cooling tower is delivered to the first pipeline under the pressure boosting of the cooling tower circulating pump through the third pipeline. Under the condition that the peak condenser, the first valve and the second valve are closed, the cold water is delivered to the reservoir through the first pipeline, the seventh valve and the fifth valve. Then the hot water of the reservoir is circulated back to the dry air cooling tower through the sixth valve, the fourth pipeline and the fourth valve. Through the circulation, the cooling of the hot water of the reservoir is realized. The peak condenser is connected with the reservoir through the first valve, the first pipeline and the fifth valve, and the dry air cooling tower is connected with the reservoir through the fourth valve, the fourth pipeline and the sixth valve. The peak condenser is communicated with the fourth pipeline through the second valve and the fifth pipeline, and the dry air cooling tower is communicated with the first pipeline through the third valve and the third pipeline. The second pipeline is communicated with the first pipeline at both ends, and the seventh valve is arranged on the second pipeline. One end of the second pipeline is communicated with the first pipeline at one side of the fifth valve, and the other end is communicated with the first pipeline at one side of the eighth valve. The DCS control center is electrically connected with the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, the eighth valve, the ninth valve and the tenth valve. The DCS control center is further used for setting the water delivery amount of the peak condenser, the dry air cooling tower and the reservoir according to actual needs of workers, and adjusting the opening degree of the corresponding valve based on the water delivery amount set by the workers.

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