Ethanol is a Widely Used Commodity Chemical With Several Applications

Ethanol is a widely used commodity chemical with several applications, including use as asolvent and as a gasoline blendstock in the fuel market. Globally, the major portion of ethanol production is based on the fermentation of sugars from crop feedstocks, such as sugarcane, corn, cellulosic material and others. World fuel ethanol production is about 85 billion liters annually, with 60% resulting from corn ethanol production in the U.S., and another 25% from sugarcane ethanol production in Brazil. In view of current environmental issues, including greenhouse gas emissions, fermentation-based ethanol is considered an alternative to fossil fuels since it originates from renewable resources. Technology Description Ethanol from sugarcane is traditionally produced by yeast fermentation of sugarcane molasses. Commonly, raw sugar is obtained as a co-product, through crystallization of sugarcane raw juice. The major process steps in sugarcane ethanol production are as follows: Milling Sugarcane is delivered from the field to the factory, where it is weighed, cut and shredded before being conducted to the mills, where the raw cane juice is extracted. Sugarcane bagasse is obtained as a residue, and it is burned to generate steam and electricity to supply process demands. Juice Treatment crystallization is completed by cooling in a crystallizer. Next. which goes to the gas-washing column. The clarifi ed juice is then concentrated under vacuum in a multiple-effect evaporator. The ethanol product stream undergoes dehydration in a molecular sieve unit. the ethanol-containing wine is sent to a distillation apparatus. This process forms a massecuite. The fi nal broth is centrifuged. The overhead of this column is sent to the gas-washing column and the vapor-side product stream. a massecuite is formed that will become the seeding solution to be used at crystallization. Meanwhile. Economic Performance . containing about 50% ethanol. Sugar Crystallization Sugar crystallization is accomplished in two vacuum calandrias. dried and sent to storage. leading to a product that is 99. and also the molasses for subsequent fermentation. In a third calandria- crystallizer set. forming a sugar syrup. The raw sugar is centrifuged. which is separated in a clarifier. Distillation The ethanol solution is heated and fed to the concentration column.5% pure ethanol. a mixture of liquor and sugar crystals. Gases released from the fermentation are washed with recycle water in a gas-washing column. where water is evaporated from the syrup and crystallization is induced by the addition of a seeding solution. is fed to a rectifying column that generates a 90% ethanol vapor stream and recycle water. Fermentation The sugars contained in the molasses are fermented to ethanol by yeast.The raw cane juice is clarified by treatment with phosphate and lime leading to mud formation. and the yeast cells are treated with sulfuric acid and recycled to the first fermenter. . in the first semester of 2013. Brazil is the main sugarcane ethanol producer and experienced. .An economic evaluation of the process was conducted based on data from the fourth quarter of 2012 (chart). The following assumptions were taken into consideration:  A 6 million-ton/yr sugarcane processing unit producing 270 million of anhydrous ethanol and 420.000 ton of raw sugar per year built in Brazil (the process equipment is represented in the simplified flowsheet)  The unit operates 210 d/yr  Storage capacity equal to 30 days of operation for sugar and ethanol  Sugarcane cultivation and harvesting costs were not considered  The electricity surplus generated in the plant is sold to the electric grid The estimated capital investment (including total fixed investment. rendering the activity flexible to market fluctuations. The process reported here allows sugarcane ethanol manufacturers to balance ethanol and sugar production yields according to demand. working capital and other capital expenses) is about $670 million. a 7% increase in fuel ethanol consumption when compared to the same period of 2012.