Sizing of biomass-fired ORC cogeneration unit within coal-fired municipal heating plant back fitting project

Silesian University of Technology, Akademicka 2A, 44-100 Gliwice, Poland

^* jacek.kalina@polsl.pl

Abstract

The problem discussed in this paper is optimal sizing of biomass-fired ORC cogeneration units into existing coal-fired district heating plants under given site-specific technical, economic and ecological constraints. In this paper the municipal heating plant in Krosno (Poland) is taken into account as the reference case. Basing on the operational experiences from this unit an optimisation study has been performed in order to examine the influence of current economic and legal conditions on the optimal design characteristics of the plant. Different electricity, biomass and coal prices are taken into account as well as the influence of the EUA (European Emission Allowance) price is examined. There are taken into account thermal energy storage and sale of electricity on balancing market. It has been found that in the studied case the implementation of hot water storage tank moves the optimal electric power output slightly towards higher values. On the other hand only a small improvement of financial performance has been gained. The results reveal importance of the optimisation of design parameters as well as the dependence of the plant’s size and structure on local economic conditions.