For a condenser of determined structure, in the ultimate vacuum, when the steam parameters and the flow rate remain unchanged, the increase in vacuum will increase the available enthalpy drop of the steam in the turbine, which will increase the power of the generator accordingly. However, by increasing the vacuum, more cooling water must be supplied to the condenser, thereby increasing the power consumption of the circulating water pump.
The condenser vacuum increases, which increases the power of the steam turbine. The vacuum value when the difference between the increased power and the electricity consumption of the circulating water pump reaches the maximum is the most favorable vacuum of the condenser (i.e. the most economical vacuum).
Detailed information:
Remarks:
Condensing steam The reason for vacuum formation in the steam turbine is that the exhaust steamThe steam turbine is cooled in condensed water and its specific volume decreases sharply. For example, when the absolute pressure of steam is 4 KPa, the volume of steam is more than 30,000 times greater than the volume of water. When the exhaust steam condenses into water, the volume is greatly reduced, forming a high vacuum on the steam side of the condenser, a necessary condition for the steam-water system to complete the cycle.
It is precisely because of the extremely high vacuum inside the condenser that all equipment connected to it may leak air into the condenser due to the laxity of non-condensable gases.
If it is not extracted in time, the pressure in the condenser will gradually increase and the vacuum will decrease, causing the steam exhaust enthalpy to increase, the droop to decrease. effective enthalpy and a decrease in the efficiency of the steam cycle of the tursteam pressure decreases. Some data shows that for every 1 KPa decrease in vacuum, the heat consumption of the unit will increase by 70 kj/kw and the thermal efficiency will decrease by 1.1%. The function of water jet air vacuum or water ring vacuum pump is to extract non-condensable gas from the condenser to maintain the condenser vacuum.
Baidu Encyclopedia-Vacuum degree of condenser