STEAM EJECTOR USED AS A SUBSTITUTE FOR COOLING TOWER IN THE ETHANOL PRODUCTION PROCESS

摘要

Nowadays petroleum dependency in transportation is widely discussed all over the world. Atmospheric pollution and global warming are deleterious consequences of gasoline consumption. Ethanol is a natural substitute fuel that has been increasingly used. One of the most important raw materials used for ethanol production is the sugar cane. The exothermic fermentation reaction of the sugar cane juice in the ethanol production process requires a rigorous temperature control. This control is usually made by using cooling water from cooling towers. The heat released from cooling towers not only has an economical cost as well as it contributes to the global heating. Steam ejectors can substitute cooling towers thus improving the ethanol production plant efficiency and reducing world heating. Furthermore, steam ejectors are smaller, cheaper and are very simple equipment when compared with cooling towers. Furthermore, its use provides an improved thermal efficiency of the production plant resulting in the reduction of the global warming effects. In this work the use of steam ejector is proposed for the fermentation cooling of a typical Brazilian sugar and ethanol production plant. The steam which feeds the steam ejector is obtained from the plant utilities and the low temperature obtained from steam expansion within the ejector is used for sugar cane fermentation process cooling. The steam ejector discharge heat is recovered as it is used to sugar and ethanol production process heating. The sugar and ethanol production plant overall energy fluxes either using coolingtowers as well as using steam ejectors are presented and theresults are compared and discussed.