REASONS BEHIND DROPPING CONDENSER VACUUM
- By : Joginder chauhan
- Category : TURBINE OPERATION
- Tags: condenser vacuum low reasons, effect of low vacuum in steam turbine, effect of vacuum on steam turbine performance, how to improve vacuum in condense how to find a vacuum leak on a steam condenser, importance of vacuum in steam turbine, surface condenser vacuum troubleshooting, TURBINE OPERATION, vacuum pulling in steam turbine
RESIN BEHIND DROPPING CONDENSER VACUUM
In this article, we discussed the causes of dropping condenser vacuum during a running time of turbine and also when we started the steam turbine The main signals of the condenser vacuum reduction during turbine running are: temperature rise at the exhaust cylinder; reduction at the vacuum meter and obvious terminal difference of the condenser. After the vacuum reduced, if maintaining the unit load without any variations, increase the inlet steam to the turbine and axial thrust force, and blade overloading.
Moreover, due to the vacuum reduction, the exhaust temperature will increase thereby making the cylinder being deformed and the unit eccentrically moving away from the center of gravity, thereafter causing unit vibration rise and the copper pipe loosening, deformation and breaking due to its expansion. It is important to check out the causes and solve in time whenever vacuum reduction appears during unit running except the stipulated load reduction. According to the different vacuum reduction speed in the condenser, two kinds of vacuum reduction are slow vacuum reduction and abrupt vacuum reduction.
The main factors for slow vacuum reduction are:
- temperature rise at the circulating water inlet
- excessive high water level at the condenser
- inadequate pressure of steam supply at the bearing seal
- wrongly shut off the sealing gate of the water seal valve during running
- the heat load at the condenser is too large
- the water level of the condensed water tank is too low
- little leakage of the vacuum system
The main factors for abrupt vacuum reduction are:
- water halting or water shortage.
- large amount of leakage in the vacuum system.
- full water in the condenser.
- halt of steam supply from the bearing seal.
- fault at the water jet pump.
- improper operation at the vacuum system valve.
- wrong opening vacuum breaking gate.
- damage at the diaphragm of the safety valve.
YOU ALSO SHOULD KNOW ABOUT RESIN BEHIND CONDENSATE CONTAMINATION AND PREVENTION:-
Condensate contamination sources and prevention:-
Typical parameters you should be able to easily check are the level of contamination l.e conductivity, orthophosphate, molybdate, chloride and iron etc. If the boiler is over cycled, treatment chemicals are overfed, or alkalinity is too high carryover may occur. Improper boiler water levels are common problems. Fire tube boilers are more prone to carryover than water tube boilers because they typically have less than steam separation equipment.
1. Hardness can come from a leaking hot water heat exchanger
2.orthophosphate can come from a leakage heat exchanger in a phosphoric acid bath and boiler carryover if the internal treatment chemistry includes phosphate.
3. Nitrite can come from a leakage heat exchanger in closed water loop.
4. Higher ph value of condensate may be an indication to an overfeed of neutralizing amine, the in leakage of caustic from a heated Bath, or boiler carryover.
Increased conductivity can be caused by any of the above. If you are lucky the uniqueness of the contaminant will lead you directly to the source.For ensuring check the condensate quality (like check ph, conductivity of the sample) of the steam header as close to the boiler as possible and before any other possible contamination source (including the neutralizing amine feed) you may be able to get a sample off the steam header steam trap. If you find contamination here, you most likely have boiler carryover occurring. This boiler carryover may either be the cause of the condensate contamination you see or be results of it. Remember that drip legs headers are there to take out carryover though.
If you think that your boiler has carryover occurring this must be corrected before you can further be finding the source of the contamination. Boiler carryover will contaminate either condensate system making any other condensate sampling a fruitless Endeavor. Work with the boiler operators to correct the problem. Empty all incoming condensate, if possible to clear the contamination from the system in the shortest period of time.
After any carryover is under control and the condensate system has had time to clear itself of the carryover contamination start testing the condensate return system for the contamination. Start first with the condensate receivers closest to the boiler. When you find out that’s contaminated work your way upstream from there. With any luck, you may be able to quickly find the source of the contamination. After some time period, the condensate contamination is seen back at the boiler the leaking piece of equipment may already be offline and any contaminated condensate flushed from its nearest condensate receiver.
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