Power projects are essentially capital intensive. Not only they involve a highly initial cost which is around Rs. 4.5 to 5.0 crores per MW for coal-based plants but also huge operation cost. The running expenses of a 210MW thermal power station may range around thirty crores every month and usually about 80% of this goes towards the fuel cost. Not only fuel cost but also fuel crises increasing day to day. It is therefore, very important that one gets the best performances from the installed power plants. The first criterion of performance is the plant output. Failure in generating the maximum output from the power plant implies a default in realizing the full return from the huge capital investment made for constructing the plant. Performance degradation by 1KW from a generating unit implies a net loss of about 1.2 lacks incurred over the plant operating life. The performance criterion that receives considerable attention is the plant heat rate. An increase in heat rate by a mere 1kcal/kwh reflects into direct increase in fuel cost by about Rs.20000 per day for 210MW thermal power plant. Boiler performance, the one of the main cause of heat rate deterioration from design value as its efficiency and evaporation ratio reduces with time due to poor combustion, heat transfer fouling and poor operation and maintenance. Deterioration of fuel quality and water quality also leads to poor performance of boiler.
The objective of present study is as follows
To observe the effect of different quality of coal on boiler performance as well as on unit performance. To study the boiler efficiency and unit heat rate by using the running parameter and investigate the various cause of performance degradation from design value. To study the effect of HPHs on boiler and overall unit performance. To study the effect of ‘THERMACT’ (solid fuel additive) dosing into boiler by direct method.
Following considerations has been made for this study:
1.Auxiliary consumption for efficiency calculation is not considered. 2.Greater than 170 MW Load is considered for this work.
3.Oil gun used data is not considered.
4.Boiler drains are neglected.
5.Relative humidity of the ambient air is assumed to be 50%. 6.Loss regarding CO formation is neglected.
7.Flue gas comprises of O2, CO2, SO2, N2 and H2O.
8.Reheater spray is isolated for our study.
The performance data value in the analysis report may be varying from plant to plant due to variation of plant condition and operating condition. But, the trend line will be almost same to all plants.
Many research works were done and also are going on in the field of coal based thermal power plant in many University, Industry and R&D laboratory. But there is huge gap of knowledge. We just gave below some overview of their work. In our work, we mainly give importance on boiler efficiency improvement. Different types of analysis are done from different point of view to maintain our expected unit heat rate (UHR). a.Exergy Analysis of coal-based 210 MW thermal power plant
It is cleared from this paper that major source of irreversibility in the power cycle is boiler, which contributes to an exergy destruction of the order of 60%. In the part load operation increases the irreversibility in the cycle and the effect is more pronounced with reduction of load. Exergy destruction increases with increasing value of condenser back pressure. Successive with drawl of HPHs shows a gradual increase of exergy efficiency for the control volume excluding boiler but efficiency increases when considering boiler for the control volume. The turbine governing system was kept at constant pressure and sliding pressure modes for their study.