| Abstract | This study aims to assess the energy conservation potential in a process factory. The scope
of study includes not only the measures in the existing facilities and process, but also the
promising options for future energy utility system after factory expansion.
Based on the facilities and processes analyzed, it is found that the energy utilization
efficiency can be further improved by enhanced thermal and operation management. It is
estimated that as much as 7.4 million Baht can be saved annually through energy efficiency
improvements, representing 5.4% reduction in the energy bill, which includes 7.6% fuel saving
and 1.1 % electricity saving. Modest investment on the relatively simple modifications/additions
in devices is required for these energy conservation options. In most case, the payback period is
only a few months, which is quite attractive from factory's viewpoint.
Natural gas cogeneration, which is also encouraged by the government of Thailand, is a
promising option to satisfy the energy utility requirement for the factory after its planned
expansion. The suitable cogeneration system for this factory is gas turbine with post-combustion
heat recovery system, which not only has the highest thermal efficiency, but also can provide the
flexibility in operation. From the financial analysis of this option, NPV, PBP, IRR are found to be
310 million Baht, 5.3 years and 26.6% respectively. Cogeneration with thermal-matching is not
feasible in this factory because the sale price of electricity to the state electric utility is not high
enough to compensate for the high investment on the prime mover. Incorporating absorption
chiller is not an attractiveness option either as the operation cost will increase in order to produce
additional steam to makeup for the shortfall in the process heat demand. Moreover, installed
capacity of compression chiller is adequate to meet all the future cooling needs of the factory.
Cool storage is an efficient measure to further improve the performance of cogeneration
system. The supply shortage from cogeneration during certain period of the day can be provided
by the cool storage. Therefore, the energy bill can be further reduced. From economic analysis,
the most feasible option is to limit the demand from the grid. The corresporting NPV, PBP, IRR
are 1.6 million Baht, 3.6 years and 35.5% respectively. |