Research On The Performance Of Auxiliary Wet Cooling System For Air Cooling Unit

The combination of dry and wet cooling system is a development direction of thermal power unit cooling system,air-cooled unit by adding auxiliary wet cooling system to become dry and wet combined cooling system.Air-cooled unit in the environment at high temperature to open the auxiliary wet cooling system,not only can solve the problem of the high pressure and the load limit,more important is to reduce coal consumption.It is very important to study the operating characteristics of auxiliary wet cooling system to improve air cooling unit efficiency.In this paper,a 600 MW air cooling unit is taken as an example to study the problem of fuzzy open condition and unreasonable mode in the operation of auxiliary wet cooling system.By analyzing the design scheme of auxiliary wet cooling system,the design parameters of exhaust steam system,condensate system,circulating water system,vacuum system and direct air-cooled condenser are determined.Based on the theory of Michael enthalpy difference,HEI condenser test standard and exhaust pressure calculation theory,a performance analysis model of auxiliary wet cooling system is established.The calculation software of peak condenser pressure and the calculation software of cooling tower inlet and outlet water temperature are compiled by using Excel macro.Based on the performance analysis model of the auxiliary wet cooling system,the clean coefficient,the performance coefficient of the cooling tower and the performance of the auxiliary wet cooling system were determined.The effects of external factors on the peak condenser pressure,the inlet and outlet water temperature of the mechanical ventilation cooling tower and the performance of the auxiliary wet cooling system are analyzed.The results show that the peak condenser pressure increases with the increase of ambient temperature,and decreases with the increase of cleaning coefficient,air volume and circulating water volume;the inlet water temperature decreases with the increase of air volume and circulating water amount,but increases with the increase of ambient temperature,and has nothing to do with altitude;the outlet water temperature of the tower increases with the increase of the ambient temperature and the circulating water volume,but decreases with the increase of the air volume of the wind turbine,which has nothing to do with the altitude;the auxiliary wet cooling system is opened to make the cooling system of the turbine more stable.The operating conditions of the auxiliary wet cooling system and the optimal operating mode are studied and the performance test of the auxiliary wet cooling system is carried out.The results show that the performance analysis model of auxiliary wet cooling system has high accuracy and the error is within 3%;under the 600 MW load,the ambient temperature above 20?to open the auxiliary wet cooling system single pump operation is the most economical,compared with the original direct air cooling mode can reduce the back pressure of 2.5k Pa or more;under the 450 MW load,the ambient temperature above 21? to open the auxiliary wet cooling system single pump operation is the most economical,compared with the original direct air cooling mode can reduce the back pressure of 1.5k Pa or more;under the 300 MW load,the ambient temperature above 20?to open the auxiliary wet cooling system single pump operation is the most economical,compared with the original direct air cooling mode can reduce the back pressure of 0.7k Pa or more.