Energetic and economical analysis of the petrochemical plant cogeneration potential

Resumo

This paper presents main results of a energetic and economical analysis performed for a petrochemical plant, by the task force of the Research and Development Unit named GECCU “Generation of Energy, Cogeneration, Combined Cycles, Rational Use of the Energy in Thermal Systems”, belonging to the Faculty of Engineering of La Plata National University. Having the plant a thermal demand of 200 ton/h 30 bar, 400 ºC superheated vapor and a 22 MWe of energetic demand; it offers a low technical cogeneration potential. The existing system, heat recovery steam generator + gas turbine, helps only with 9.2 MWe and 20 MWth. Therefore, a substantial steam amount must be generated by conventional boilers. Theoretically it would be convenient to increase vapor production by cogeneration, but the relationship between the electricity and heat productions would be larger than that of the Plant demands. Two alternative options were analyzed. In the former it was considered to continue operating the existing old cogeneration unit under the same operating conditions, taking account the predicted retrofitting cost, which implies a specific cost of the order of new equipment. The later considers the installation of new and bigger cogeneration unit. Results are analyzed and discussed.