IECP — an approach for integrated environmental and cost evaluation of process design alternatives and its application to evaluate different NOx prevention technologies in a 125 MW thermal power plant

This paper proposes a methodology, IECP (integrated environmental and cost potential), for the integrated environmental and cost evaluation of a process design option. It is designed for a quick quantitative evaluation of a design option at different levels of process synthesis or retrofit applications. A hazard based approach, Pro-hazard, has been developed for the quantitative evaluation of environmental potential of design options by using a cradle-to-gate life cycle assessment. This assigns an environmental potential index to a design option by comparing its environmental performance with respect to the base option. To quickly evaluate the cost of the resulting option a simple approach, Eco-index, has been developed. It gives a cost potential index to a specific design option by comparing its unit operating and fixed cost with respect to that of the base option. In the IECP framework, both the environmental potential and cost potential indices for a design option are combined by assigning an appropriate weighting factor to each index, which gives an integrated index, IECP, for the design option.In this paper, the IECP methodology has been combined with a process simulator, Aspen HYSYS, to obtain the necessary data to quickly and accurately determine the IECP index. The applicability of the proposed IECP approach has been demonstrated through a case study for the selection of potential NOx prevention options in a 125 MW combined cycle power plant from a large number of options related to flue gas recirculation, steam and water injection to the furnace.

Research Highlights
► A novel integrated methodology for process design and decision-making.
► Unique set of indices to evaluate economic as well environmental performance of any design option.
► Integration of different indices into a process design and decision-making framework.
► Implementation of the methodology using a process simulation Tool Aspen HYSYS.