Answer Posted / sethu
How vacuum is created?
Basic vacuum created in the LPT exhaust side is because of condensing process. Phase change is occurring at the exhaust side i.e. conversion of steam into water. Specific volume of water is much lower than the steam.Hence when the condensing process happens, volume of steam reduces and basic vacuum is created.
Apart from this, vacuum pumps are provided to remove non condensable gases/air ingress which reduces heat transfer effectiveness.
Why vacuum is created?
To improve LPT cylinder efficiency & thus the load/work done shall be improved.
Effect of over vacuum?
It causes sub-cooling effect where hot well temperature reduces more than design which required to be added in boiler leads to heat loss. Also flow accelerated erosion in LPT last stages.
Effect of under vacuum?
LPT efficiency reduction which causes lesser work done & leads to reduced load output.
| Is This Answer Correct ? | 59 Yes | 5 No |
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