Energy and exergy analyses of a fluidized bed coal combustor steam plant in textile industry

In this study, the analyses of first and second laws of thermodynamic are presented for a 6.5 MW power plant located in Adana, Turkey. The system components, examined in the present study, are listed as a fluidized bed coal combustor (FBCC), a heat recovery steam generator (HRSG), an economizer (ECO), fans, pumps, a cyclone and a chimney. All of the system components are examined one by one and the energy and exergy analyses are carried out for all of the system components. The highest value of irreversibility is observed in the FBCC, about 93% of the entire system irreversibility tracked by HRSG and ECO with 3% and 1%, respectively. The high excess air value, which is the primary origin of irreversibility, causes the heat losses from the FBCC, due to the increment in mass flow rate of the combustion gas. Moreover, the high excess air value gives rise to occurrence of low combustion efficiency in FBCC which can be decreased through decreasing flow rate of air with decreasing oxygen. Secondly, changes in the energy and exergy efficiencies are examined employing different ambient temperature. As the ambient temperature increases, the second law efficiencies of FBCC and HRSG increases but efficiency of ECO decreases.