Abstract:
The aim of this thesis is to evaluate the potential of improvement on the existing cogeneration system in a large paper mill. The cogeneration systems, of which the installed capacity is 3.56 MW , is back - pressure turbine type . Base on pressure and flow rate of steam requirements in the processes, the options of modified cogeneration system had been evaluated based on both technical and financial analyses. From the energy audit, it was found that the first law efficiency of the existing cogeneration system was about 72.7% and the pressure of supplied steam to some processes were hight than the requirement. Thus the method of improvement was evaluated through the various operating conditions of the improvement cogeneration system.According to the economic criteria, there are six feasible cases with the new installed capacities in the range of 423-577 KW , and the net increase in the genarted electricity expenditure was about 2,678,080- 3,232,147 baht/y. The payback period at 8% discount and internal rate of return after tax were 3.1 - 4.0 years and 27.6 - 29.1 %, respectively.