Kemija u Industriji (Nov 2007)
Cogeneration and Heat Recovery in the Industrial Process
Abstract
Related to energy requirements for non-cellulose i. e. polyester production as an energy-intensive process, potential saving options are proposed. From the process data, it is evident that unit operations need electric and thermal energy in significant amounts. At the same time, improved energy management could be realized by applying a combined heat and power system (CHP) instead of the usually used process with separate heat and power production. In addition, the boiler flue gases with a sufficiently high outlet temperature could be used for combustion air preheating.Considering industrial process data, a calculation and comparison between the primary energy demand for conventional, CHP system and flue-gas heat recovery is presented. Comparison between separate heat and electricity production i.e. the conventional system with an overall efficiency of 55.6 % and CHP with efficiency of 85 %, shows an absolute efficiency increase of 29.4 %. Using an air preheater for combustion air temperature increasing saves 5.6 % of the fuel and at the same time diminishes thermal pollution because the exhaust flue-gas temperature becomes 77.3 °C instead of 204 °C. Conclusively, cogeneration and flue-gas heat recovery presentsfuel savings, which also implies economic and environmental benefits.
