Energy-saving cooling method and system for reducing exhaust steam pressure of air-cooled unit in power plant

Abstract

The invention discloses an energy-saving cooling method and an energy-saving cooling system for reducing exhaust steam pressure of an air-cooled unit in a power plant, which are used for solving the problem that power output of the air-cooled unit is blocked in summer. According to the method, the exhaust steam pressure of the air-cooled unit is reduced by setting refrigerating equipment and adopting the following measures: (a), the working solution of a water-ring vacuum pump is cooled by chilled water prepared by the refrigerating circulating equipment through a cooler, and the temperature of the working solution is reduced to a set value; (b), the industrial desalted water is cooled by the chilled water prepared by the refrigerating circulating equipment through the cooler, one part ofthe cooled industrial desalted water is used for evaporative cooling of the outlet air of an axial flow fan of the air-cooled unit through a nozzle, and the other part of the cooled industrial desalted water enters a steam turbine exhaust pipeline; and (c), the condensed water is divided into two parts through a condensed water pump, wherein one part of the condensed water enters a steam turbine heat regenerator and is delivered to a boiler, and the other part of the condensed water is cooled by the chilled water prepared by the refrigerating circulating equipment through the cooler, enters the steam turbine exhaust pipeline and is mixed with the exhaust steam to absorb latent heat of vaporization. By the improvement, the exhaust steam pressure of the air-cooled unit in the power plant can be effectively reduced, and safe and economic operation of the unit in summer is ensured.

Description

technical field [0001] The invention relates to an energy-saving technology for power generation, in particular to an energy-saving cooling method and system capable of improving the thermal economy of an air-cooling unit and reducing the exhaust pressure of an air-cooling unit in a power plant in summer. Background technique [0002] Because air-cooling technology can save a lot of water resources, it has achieved rapid development in areas rich in coal and poor in water. In recent years, the air-cooling technology of power plants at home and abroad has made great progress and achieved remarkable results. The air cooling systems currently used in power plants are: direct air cooling system; indirect air cooling system (Harmon system) using surface condenser; indirect air cooling system (Heller system) using hybrid condenser. Among them, the direct air cooling unit uses air as the cooling medium to directly cool the exhaust steam of the steam turbine through the finned tube...

AI Technical Summary

Problems solved by technology

[0003] The air-cooled condenser of the direct air-cooled unit has a huge space and is in a negative pressure state, so the probability of air entering the exhaust space of the steam turbine is greatly increased, forming air resistance, greatly reducing the heat exchange effect, and further pushing up the exhaust pressure

However, the water ring vacuum pump for pumping non-condensable gas is vaporized due to the high temperature of the working fluid, which seriously affects the vacuum pumping ability of the vacuum pump, so that the non-condensable gas in the air cooler cannot be pumped out in time. If it is operated for a long time In the case of vaporization, not only the heat transfer of the air-cooled radiator deteriorates, the vacuum becomes poorer, but also the vacuum pump impeller cavitation occurs, which affects the safe operation of the equipment

In order to increase the output of direct air-cooled units in summer, some power plants use the method of increasing the speed of air-cooled fans to improve the heat exchange effect. However, since the air-cooled fans are basically running at full speed in summer, there is not much room for speed increase, even if it can be improved. Power consumption, but the effect is not obvious; there are also power plants that directly spray a large amount of desalted water on the finned tube bundle radiator to enhance the heat exchange effect

Although this method can improve the vacuum of the unit, but because the water temperature is still high, more chemical water needs to be sprayed, and the cost of water production is high and the waste is serious; some people also suggest installing a set of wet cooling devices, using dry water in summer +Water combined method to increase the output of the unit, but on the one hand, this method requires a large system transformation of the unit, and the investment cost is relatively large, and it is also very difficult to arrange a wet condenser on the air-cooled unit

The above methods are not optimal for large direct air-cooling units that have been put into operation

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