System and method for adjusting backpressure through waste heat energy storage of air cooling unit
阅读说明：本技术 一种空冷机组余热储能调节背压系统及方法 (System and method for adjusting backpressure through waste heat energy storage of air cooling unit ) 是由 张振华 杨国强 杜未 周雅君 刘岩 梁文龙 高世杰 张浩峰 吴韬 胥佳瑞 青可儿 于 2020-06-17 设计创作，主要内容包括：本发明涉及一种空冷机组余热储能调节背压系统及方法,该系统包括汽轮机、空冷岛、换热器及储热罐；所述汽轮机排汽口通过蒸汽管路与所述空冷岛进汽口相连通；所述汽轮机排汽口通过蒸汽管路与所述换热器进汽口相连通；所述空冷岛进汽入口与所述换热器进汽入口通过蒸汽管路相连通；所述换热器进出口通过水管路与所述储热罐的进出口相连通。本发明可在直接空冷机组环境气温较低时段,通过储热罐系统储存一定排汽热量即低温冷量,可以在较冷季节避免机组处于极限背压以下状态运行,确保机组末叶安全和机组防冻安全。同时,在环境气温较高时段,通过储热罐系统将冷量用于冷却机组高温排汽,以降低机组背压,实现高温时段的节能运行。(The invention relates to a system and a method for regulating backpressure by waste heat energy storage of an air cooling unit, wherein the system comprises a steam turbine, an air cooling island, a heat exchanger and a heat storage tank; the steam turbine exhaust port is communicated with the air inlet of the air cooling island through a steam pipeline; the steam turbine exhaust port is communicated with the steam inlet of the heat exchanger through a steam pipeline; the air cooling island steam inlet is communicated with the heat exchanger steam inlet through a steam pipeline; and the inlet and the outlet of the heat exchanger are communicated with the inlet and the outlet of the heat storage tank through water pipelines. The invention can store certain steam exhaust heat, namely low-temperature cold energy, by the heat storage tank system in a time period when the ambient temperature of the direct air cooling unit is lower, can prevent the unit from running in a state below the limit back pressure in a cold season, and ensures the safety of the last leaves of the unit and the anti-freezing safety of the unit. Meanwhile, in a time period when the ambient temperature is higher, the cold energy is used for cooling the unit high-temperature exhaust steam through the heat storage tank system so as to reduce the backpressure of the unit and realize the energy-saving operation in the high-temperature time period.)
1. The waste heat energy storage and backpressure regulation system of the air cooling unit is characterized by comprising a steam turbine, an air cooling island, a heat exchanger and a heat storage tank; the steam turbine exhaust port is communicated with the air inlet of the air cooling island through a steam pipeline; the steam turbine exhaust port is communicated with the steam inlet of the heat exchanger through a steam pipeline; the air cooling island steam inlet is communicated with the heat exchanger steam inlet through a steam pipeline; and the inlet and the outlet of the heat exchanger are communicated with the inlet and the outlet of the heat storage tank through water pipelines.
2. The operation method of the air cooling unit waste heat energy storage and backpressure regulation system is characterized by comprising the following steps:
when the ambient temperature is low at night, part of the discharged steam at the lower temperature of the steam turbine enters the heat exchanger, and the cold energy is stored in the heat storage tank through the water medium of the surface heat exchange circulation to adjust and improve the back pressure and prevent the unit from exceeding the limit back pressure;
the high time period of daytime environment temperature, the partial steam extraction of the high temperature of steam turbine gets into the heat exchanger, through the circulating aqueous medium of surface heat transfer with the low temperature time period at night the cold volume of storing in the heat storage tank for cool off high temperature steam extraction to the regulation reduces the backpressure.
Technical Field
The invention belongs to the technical field of thermal power generation, and particularly relates to a system and a method for adjusting back pressure by storing energy of waste heat of an air cooling unit.
Background
The large-scale air cooling unit is widely adopted as a water-saving power generation mode, makes an important contribution to water-saving power generation and plays an important social benefit.
Compared with a wet cooling unit, the direct air cooling unit can save 80% of power generation water consumption due to the adoption of an air cooling mode, and has important use value for water-deficient areas.
However, after the direct air cooling unit adopts air cooling to exhaust steam, the backpressure is often designed to be much higher than that of a wet cooling unit due to the heat exchange efficiency and the ambient temperature of an air cooling island, and the backpressure of the unit is higher in summer and in the daytime high-temperature period of one day, so that the power generation economy of the unit is influenced, and even the operation safety and the full load of the unit are influenced.
Therefore, in the air cooling unit, especially in the direct air cooling mode, it is necessary to research measures for reducing the back pressure in the high temperature period, so as to ensure the safe and economic operation of the unit.
Disclosure of Invention
The invention aims to provide a system and a method for regulating back pressure by waste heat energy storage of an air cooling unit.
The invention provides a waste heat energy storage and backpressure regulation system of an air cooling unit, which comprises a steam turbine, an air cooling island, a heat exchanger and a heat storage tank, wherein the steam turbine is connected with the air cooling island; the steam turbine exhaust port is communicated with the air inlet of the air cooling island through a steam pipeline; the steam turbine exhaust port is communicated with the steam inlet of the heat exchanger through a steam pipeline; the air cooling island steam inlet is communicated with the heat exchanger steam inlet through a steam pipeline; and the inlet and the outlet of the heat exchanger are communicated with the inlet and the outlet of the heat storage tank through water pipelines.
The invention also provides an operation method of the waste heat energy storage and backpressure regulation system of the air cooling unit, which comprises the following steps:
when the ambient temperature is low at night, part of the discharged steam at the lower temperature of the steam turbine enters the heat exchanger, and the cold energy is stored in the heat storage tank through the water medium of the surface heat exchange circulation to adjust and improve the back pressure and prevent the unit from exceeding the limit back pressure;
the high time period of daytime environment temperature, the partial steam extraction of the high temperature of steam turbine gets into the heat exchanger, through the circulating aqueous medium of surface heat transfer with the low temperature time period at night the cold volume of storing in the heat storage tank for cool off high temperature steam extraction to the regulation reduces the backpressure.
By means of the scheme, the system and the method for adjusting the backpressure through the waste heat energy storage of the air cooling unit can store certain steam exhaust heat, namely low-temperature cold energy, through the heat storage tank system in a time period when the ambient temperature of the direct air cooling unit is low, the unit can be prevented from running in a state below the limit backpressure in a cold season, and the safety of the tail leaves of the unit and the anti-freezing safety of the unit are ensured. Meanwhile, in a time period when the ambient temperature is higher, the cold energy is used for cooling the unit high-temperature exhaust steam through the heat storage tank system so as to reduce the backpressure of the unit and realize the energy-saving operation in the high-temperature time period. For a typical 600MW direct air cooling unit, by adopting the system and method and the configuration of a heat storage tank system with a certain capacity, the back pressure of the unit can be reduced by 5kPa in a high-temperature period of summer environment, and the coal consumption is reduced by about 5 g/kWh. Meanwhile, the unit can be ensured to operate above the limit back pressure in a low-temperature period in winter, and the freezing injury is reduced.
The foregoing is a summary of the present invention, and in order to provide a clear understanding of the technical means of the present invention and to be implemented in accordance with the present specification, the following is a detailed description of the preferred embodiments of the present invention.
Drawings
Fig. 1 is a schematic structural diagram of a waste heat energy storage and backpressure regulation system of an air cooling unit.
Reference numbers in the figures:
1-a steam turbine; 2-air cooling island; 3-a heat exchanger; 4-heat storage tank.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Referring to fig. 1, the embodiment provides a system for adjusting backpressure by storing energy of waste heat of an air cooling unit, which includes a steam turbine 1, an
Through setting up heat exchanger 3 and its heat storage tank 4 system of operation side by side with
The operation method of the waste heat energy storage and backpressure regulation system of the air cooling unit comprises the following steps:
when the ambient temperature is low at night, part of the discharged steam at the lower temperature of the steam turbine 1 enters the heat exchanger 3, and the cold energy is stored in the heat storage tank 4 through the water medium of the surface heat exchange circulation so as to adjust and improve the back pressure and prevent the unit from exceeding the limit back pressure. The average ambient temperature in the low temperature period in summer is 23 ℃, the exhaust temperature of the steam turbine 1 at rated load is 60 ℃, the exhaust back pressure is 22kPa, and the exhaust flow entering the heat exchanger 3 is about 176 t/h.
When the ambient temperature is higher in daytime, part of the exhaust steam with higher temperature of the steam turbine 1 enters the heat exchanger 3, and the water medium circulated by surface heat exchange is used for cooling the cold energy stored in the heat storage tank at low temperature at night for high-temperature exhaust steam to adjust and reduce the backpressure. The average ambient temperature in the high temperature period in summer is 40 ℃, the exhaust temperature of the steam turbine 1 at rated load is 77 ℃, the exhaust back pressure is 40kPa, and the exhaust flow entering the heat exchanger 3 is about 176 t/h.
The cold energy stored in the heat storage tank 4 is further cooled by the low-temperature exhaust steam of the steam turbine 1 in the low-temperature period, the back pressure of the steam turbine 1 in the high-temperature period can be reduced from 40kPa to 35kPa, and the coal consumption is reduced by about 5 g/kWh.
By the air cooling unit waste heat energy storage backpressure adjusting system and the method, certain exhaust steam heat, namely low-temperature cold energy, can be stored by the heat storage tank system in a time period when the ambient temperature of the direct air cooling unit is low, the unit can be prevented from running in a state below the limit backpressure in a cold season, and the unit end leaf safety and the unit anti-freezing safety are ensured. Meanwhile, in a time period when the ambient temperature is higher, the cold energy is used for cooling the unit high-temperature exhaust steam through the heat storage tank system so as to reduce the backpressure of the unit and realize the energy-saving operation in the high-temperature time period. For a typical 600MW direct air cooling unit, by adopting the system and method and the configuration of a heat storage tank system with a certain capacity, the back pressure of the unit can be reduced by 5kPa in a high-temperature period of summer environment, and the coal consumption is reduced by about 5 g/kWh. Meanwhile, the unit can be ensured to operate above the limit back pressure in a low-temperature period in winter, and the freezing injury is reduced.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
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