Thermal Economy And Numerical Study Of Atomized Water System In Exhaust Pipe Of Direct Air-cooling Unit

In some Chinese areas, coal resources are rich while water resource is scarce,so those areas are not suitable for the development of the wet cooling unit.Beca use the air-cooling units use air instead of cooling water as the cooling substance to cool the exhaust steam of turbine, it can save a large amount of cooling wat er and have good prospects for development. When the air-cooling unit operating,there are many problems, such as the existence of high back pressure in a wide range, scaling easily in winter when condenser running, dissolved oxygen content of condensate water exceeding the standard and cooling performance of condense r affected by environments. All these problems will affect the unit vacuum, thus a ffecting the thermal economy of unit. In order to improve the vacuum and the th ermal economy of unit and provide a theoretical basis of energy consumption for the direct air-cooling unit, this paper aims at the existing problems of the cold end of unit, takes the direct air-cooling unit as the main research object and put for ward the scheme that atomized water system installed in the appropriate position in the exhaust pipe, in this way the cold end heat can be recovered and the condense r heat load can be reduced.When the vacuum of unit is low, the atomized water system can spray demin eralized water into the pipe to reduce the condenser heat load and improve the un it vacuum; In addition, this scheme can also be carried out in the make-up water of thermodynamic system, make-up water will be set by directly into the hot well inste ad of atomization in exhaust pipe before entering the hot well, so as to achieve the waste heat utilization and improve the vacuum of unit in unit cold end and enhan ce the thermal economy of unit.In order to verify the correctness of the atomized water system, this paper firstl y applied the system in make-up water of the thermodynamic system. With the eq uivalent enthalpy drop method as the theoretical foundation, establishing a physica l model and thermal economy model of atomized make-up water in exhaust pipe,taking exhaust pipe of NK600-24.2/566/566 as an example, thermal economy ind exes were calculated and analyzed in two ways: make-up water of the hot well and atomized make-up water in exhaust pipe and verifying the correctness and sup eriority of the scheme.When the atomized water system was applied for simple desalted water atomiz ation, desalted water flowed into a water collection tank through corresponding pipe lines, while captured and collected by exhaust pipe. Establishing a physical and mat hematical model of the atomized water system in exhaust pipe of direct air cooling unit, By using the numerical method, analyzing the influence of the position of t he nozzle, the spray angle, the nozzle pressure, the nozzle diameter and quantity of make-up water on the atomization effect, obtaining the distribution of temperat ure field and velocity field in exhaust pipe and analyzing the change of pressure loss in exhaust pipe.In order to further improve the vacuum of unit, a improved scheme of nozzle arrangement was put forward which obtaining the distribution of field in exhaust pipe and the best scheme of nozzle arrangement.