STEAM GENERATION AND DISTRIBUTION NETWORK ANALYSIS, INCLUDING COGENERATION SYSTEM! AT STAR PAPER MILLS LTD.; SAHARANPUR

Abstract

It is found that the Paper industry is the • third_ highest consumer, of electrical power & water after Steel and Petrochemical industries. With foreseeable future of energy crisis & incremental fuel cost . in 20th Century, it. has become important that the mill should generate its own power at the lowest possible cost simultaneously fulfilling all the process steam demand. So it leads to do energy audit of the present mill and proposed for an • efficient cogeneration cycle which will increase the mill energy conversion efficiency from 50% to Indian standard practice of 58%. Here in this dissertation an effort has been made to analyze the performance of steam' generator, steam distribution and cogeneration cycle technically as well as more economically. Chapter two evaluates the efficiencies of different steam generators. It is seen that the thermal efficiency of C/F boilers . is 64%.' It is only due to variation in coal grade with low C. V of 4500 kcal/kg and absence of air preheater, otherwise the efficiency could have reached above 70%. The recovery boiler also gives nearly 65-70% of thermal efficiency with chemical recovery efficiency of 70% which are quite low and efforts should be made to increase the chemical recovery efficiency at least to 85 % by retrofitting to increase its economic viability and environmental compatibility. Chapter three notes the per day steam consumption chart & hence draws the steam balance diagram for the, total cycle of the mill. It checks the sizing of pipe lines & finds 776 Tons of 80 PSI steam and 876 tons of 40 PSI steam lost due to condensation in steam pipe lines & radiation. Mill data indicated that about 10 Tons of steam per day is lost through different systems and media' faults. The annual steam loss cost, if there is a leak in the steam pipe lines, has also been calculated. Chapter four analyzes the feasibility of a cogeneration system. It is observed that, the present cogeneration system with a bottoming cycle can never lead, the mill energy conversion efficiency more than 50% & cogeneration cycle efficiency utilization factor not more than 70-75 %. The mill total heat demand ratio is to power demand found to be 7.6:.1 which lags the effective cogeneration system heat to power ratio value of 5:1. The power cost is found to be Rs.2.90/- per unit at the load of 3.8 MW. So it is advised to maintain the turbine load in between 3.2-3.9 MW out of a 5 MW capacity BHEL turbine. Chapter five proposes for an Atmospheric Fluidised Bed Combustion boiler cogeneration cycle which can generate 12.483 MW of power fulfilling all the process steam needs of future mill of 200 TPD capacity. This topping cycle will lead to mill energy conversion of nearly 55 % and return on investment is about 20 % over. the ROI of 10% on the present system. The heat to power ratio can be improved to 6:1 & expected pay back period found to be 5-6 yrs. The power cost is Rs. 1.13/kwl leading to a saving of approx in 11.3 Cro,res over the present system of power generation per annum. Chapter six concludes the dissertation