The degree of subcooling of the condensate water: It is the difference between the temperature of the saturated water under exhaust pressure and the actual temperature of the condensate water. In other words: the difference between the saturation temperature of the vapor and the temperature of the condensate under the condenser pressure is called subcooling.
The main reasons for supercooling of condensate water:
1. Defects in the condenser structure.
2. The water level in the condenser is high. Part of the copper tubes are flooded with condensed water, resulting in supercooling.
3. An air leak from the vapor side of the condenser or a malfunction of the air extraction equipment causes partial pressure of the vapor in the condenser. the condenser drops, causing supercooling.
4. The copper tube of the condenser broke and a large amount of circulating water leaked out.
5. There are trop of cooling water in the condenser or the water temperature is too low.
The main effects of increased condensate subcooling:
1. Increased oxygen capacity
2. Increased coal consumption
Steam turbine condensation High. water temperature
The saturation temperature at the condenser pressure minus the condensate temperature is called “subcooling”. Theoretically, the condensate water temperature should be equal to the saturation temperature under the condenser exhaust steam pressure, but in fact, the influence of various factors makes the condensate water temperature lower than the saturation temperature under the exhaust vapor pressure.
The reasons for condensate subcooling are:
① There are defects in the condenser structure. There is not enough passage for steam between the beamsx of tubes towards the lower part of the condenser. , so that the condensate flows from the upper pipe and falls onto the lower pipe to be cooled again. If there is no steam flow for heating, when the condensed water flows into the hot well, the degree of subcooling will increase.
② The water level in the condenser is so high that some copper tubes are immersed in the condensed water, causing supercooling.
③ An air leak from the vapor side of the condenser or a malfunction of the vapor extraction equipment causes the vapor partial pressure in the condenser to drop and causes subcooling.
④ The copper tube of the condenser breaks, and the condensed water seeps into the circulating water (at this time, the quality of the condensed water deteriorates seriously, e.g. hardness exceeds the standard).
⑤ There is too much cooling water in the condenser or the temperaturere water is too low.
Let me express my opinion. You should be aware that the unit condenses steam under normal conditions (i.e. non-accidental conditions, serious vacuum system leaks and exhaust steam temperature increases caused). by breath friction). Steam turbine vacuum is the temperature of the turbine exhaust steam. The higher the vacuum, the lower the exhaust gas temperature. This is determined by the principle of operation of the steam turbine. To put it simply, the saturation temperature and vapor pressure match perfectly. For example: water boils at 100°C under atmospheric pressure. But as the pressure increases, the boiling temperature increases. Likewise, as the pressure decreases, the boiling temperature also decreases. Just like on the Qinghai-Tibet plateau, water can boil at 80degrees Celsius. Ideally, in the condenser of the steam turbine, the working fluid (steam-water) is in a balanced state, that is, the cooling water flowing into the condenser only removes the latent heat of vaporization of the steam and does not cool the steam. This is our ideal state, without hypothermia. At this time, the temperature corresponding to the condenser should be the water saturation corresponding to the absolute pressure of the condenser.temperature. That said, I just want to change one of your misunderstandings: to lower the exhaust steam temperature, you just need to increase the condenser vacuum. This doesn't mean that lowering the exhaust steam temperature will increase the vacuum like you think. is a cause and effect relationship. If you understand this problem, I will give you some simple and effective ways to increase vacuum. 1. Try increasing the amount of cooling water in the condensity. If the circulating water temperature is high in summer, various power plants use a common method to increase the circulating water pump. 2. If it is a closed circulating water system cooled by a cooling tower, the inlet water flow of the circulating water tower can be increased and the inlet temperature of the condenser cooling water can be reduced. If the cooling tower has a backup water source, it is best to use deep underground well water because the temperature of deep well water is low. 3. Check the condenser vacuum for tightness and eliminate leaks. 4. If a waterjet steam extractor is used, try to lower the water temperature in the waterjet tank to below 35°C.