An Alternative boiler fuel in a paper manufacturing plant

Abstract

As the cost of production of the paper manufacturing plant in the case study has been impacted greatly by the skyrocketing price of fuel oil for its boiler, the objective of this research is to find an alternative fuel to replace fuel oil along with proposing appropriate technology to support the selected fuel. The study will help reduce the cost of production in order to increase competitiveness of the company in the market. Related data were first gathered including the process and requirements of the current boiler, available boiler technologies and alternative fuels. The analysis of available alternatives resulted in proposed potential solutions for the case study company. The proposed alternatives were, then, analyzed in feasibility studies addressing technical, operational, environmental, and financial feasibility. By weighting on availability and reliability, bituminous coal was proposed as the alternative fuel along with proposed combustion technologies that were suitable for a coal fire boiler and met the steam requirement of the case study company. Two technologies were identified and evaluated, namely traveling grate spreader stoker (TGS) and circulating fluidized bed (CFB). In technical analysis, CFB has a higher burning efficiency of 85-90% compared to 78-85% for TGS. It is also more flexible to humidity and ash contents in the coal, more capability to control access air, less access air required, etc. Both technologies would require three operators compared to two operators for the fuel oil boiler. The extra operator would be needed for fuel handling and ash removal. In environmental analysis, as CFB has a lower temperature in the combustion chamber, the chance of NO[subscript x] emissions occurring is lower than for TGS. Also, CFB allows addition of limestone during the combustion process, whereby SO[subscript x] is better captured by CFB technology. However, both technologies meet the SO[subscript x] and NO[subscript x] emission regulations. Lastly, the financial analysis which calculated the cost efficiency of bituminous coal with each boiler technology showed that the NPV value of CFB is greater than TGS’s value (239.63 million baht and 236.34 million baht, respectively). As a result, the best alternative is using bituminous coal and implementing CFB with which the cost of production can be reduced to 8.5% of the original cost.