Assessment of Standby Evaporator as an Energy Conservation Measure: Case of Sudanese Sugar Industry

Abstract

This work presents analysis of historical data of four Sudanese sugar factories namely Assalaya, Sennar, Gunned and New Halfa. The historical data covers more than 40 years . In about 38 years of this period the sugar industry operates with one set of evaporator. In 2005 a standby set of evaporator is installed in each factory. The installed set of evaporator is similar in configuration (Robert type) to existing set however, with a relatively large heat transfer area and made of stainless steel rather than brass. The result of the analysis revealed that before 2004 the total downtime is 26.6% (53 days) of the operation period on average; 10.4 days (19.6%) of which is for evaporator scale removal. The provision of standby evaporator has completely eliminated the evaporator downtime. The improvement in total downtime has made significant saving on bagasse. The bagasse saved in 10 days is 14379 ton ($215691 based on bagasse price $15/ ton). The shortening of crop season made by standby evaporator has saved the sugar cane from over maturation and improved sugar recovery by 0.2% (from 9.3 to 9.5%). The savings due to bagasse and sugar recovery only made the evaporator payback period of 2.8 years. The standby evaporator has also improved the overall steam economy and evaporation coefficient. The steam economy of the standby and existing sets of evaporators is about 3.1 and 2.6 respectively.