Modeling and analysis of total site heat and power cogeneration from an exergoeconomic approach in a 4 MW case study

In design and analysis of total site of heat and power cogeneration, how to arrange equipment has a unique importance in production process. Due to high cost of turbines setting up and fuel demand for power plants that generates required steam for turbines, suitable design of these arrangements can save or in front of it create unjustified extra costs. In this paper, using an Iterative Bottom-to-Top Model (IBTM) which is a new modified cogeneration targeting method, cogeneration potential is estimated and fit to it, temperatures of steam levels, power generation, fuel and steam flows and the amount of boiler heat load are calculated. First steam turbines arrangement between steam levels for case study is designated and if required power is not provided in total site by steam turbines, use of gas turbine or condensing turbine to generate additional power are checked. The results of the research showed that the selected scenario of back pressure steam turbines arrangement beside gas turbine system, has maximum exergy efficiency, minimum exergy destruction and minimum total capital cost rate and exergy destruction cost rate. Finally, mixed use of back pressure steam turbines beside gas turbine system, were suggested as the best arrangement from an exergoeconomic approach.