hi,would i be correct in assuming that all limiting factors remaining constant, an increase in boiler steam pressure will also increase output to turbine and of power generated? also, if so, will increasing pressure through using more coal (thru quantity/quality) also necessitate high amount of expenditure on refurbishing the systems?thankssameer
You are correct in the first part - increasing boiler pressure will increase turbine output as the higher pressure steam will contain more heat energy. As for the second part, I will say a cautious yes. Increasing the coal quantity will increase demand and wear on conveyors transporting the coal, increased wear on the milling plant grinding the coal (assuming modern pulverised fuel plant) and increased demand on the fans both supplying combustion air and removing flue gases. I do not see a great change in wear on these fans so I do not think there will be an increased maintenance need. There will also be a greater demand and wear on the ash and dust disposal plant with resultant increased maintenance requirement. As far as changing the quality of the coal is concerned, if the new coal has a higher calorific value but the same hardness and ash content, there will be a higher heat output to the steam but no extra demand on milling plant and ash disposal plant. However, if the hardness of the coal rises, there will be increased wear and increased maintenance. Sorry if the last part is a qualified answer but it really depends on how the coal changes - calorific value, hardness, ash content etc....
