I am interested to know that how the following factors influence the heat rate of a power plant? i. Main and reheat steam spray (ii). Air ingress in the condenser (iii). Poor pulverization of coal (iv). Increase in condenser vacuum (v). Leakage across the HP heater bypass line (vi). Poor maintenance of cooling tower fill materials.
If you are looking for qualitative answers, the following may help. When speaking of heat rate, it is easy to get terminology backwards. Efficiency decreases as heat rate values increase, that is, higher heat rate values mean lower efficiency. Nevertheless, people sometimes talk about increasing heat rate in a colloquial sense that means increasing efficiency, hence the potential confusion. Improving heat rate means decreasing its value, not increasing it. The answers below assume that by increased heat rate (values) we mean decreased efficiency.
1. stream spray increases heat rate (decreases efficiency) because it decreases steam temperature. It is designed to control tube temperatures and steam temperatures. The decrease is small but measurable.
2. Air ingress in the condenser is significant steam-side corrosion concern. (I assume you mean air ingress on the low-pressure working fluid side of the compressor). It also increases heat rate (decreases efficiency) by decreasing the effectiveness of condenser cooling water. However, the corrosion concerns are so large that well-managed plants minimize air ingres and so it is less often a significant factor in heat rate, but the corrosion and materials issues are probably more important than heat rate to the overall plant management.
3. Poor pulverization usually will affect unburned carbon and therefore increases heat rate. It additionally compromises the potential sale of fly ash as a cement admixture and often deposit formation and fire-side corrosion.
4. Increase in condenser vacuum is generally accomplished by a decrease in condenser cooling water and, if so, will decrease heat rate (increase efficiency). There are a few other ways to decrease vacuum, nearly all of which will increase the turbine pressure ratio and therefore improve power output or heat rate.
5. Leakage across the HP bypass line increases heat rate (decreases efficiency).
6. Poor maintenance of anything in the cooling tower increases cooling water temperature and hence increases heat rate (decreases efficiency) by both decreasing temperature/pressure ratio in the turbine and by increasing parasitic loads to compensate for the warmer water.
Dear Amit
You can read the attached article and use the helpful information.
Article Energy and exergy analysis of Montazeri Steam Power Plant in Iran
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