Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 2, No.12, December 2013 www.borjournals.com Blue Ocean Research Journals 55 A Theoretical Novel Design Approach To Enhance The Evaporator Steam Economy Of Large Scale Sugar Industries In Ethiopia M. Sathiyamoorthy, Department of Chemical Engineering, College of Engineering, Defence University, Debrezeit, Ethiopia, North East Africa Amanuel Gebrekrstos, Department of Chemical Engineering, College of Engineering, Defence University, Debrezeit, Ethiopia, North East Africa G.Balachandran , Department of Chemical Engineering, Mekelle University, Mekelle, Ethiopia, North East Africa. Abstract The sugar industries are one of the major food industries in all countries in terms of demand, capacity and consumption. According to the Ethiopian country’s statistical report, the demand of sugar is tremendously increasing. To meet the demand and the requirements of sugar, many sugar industries are established. The existing sugar industries are operating with high steam consumption and less production capacity. The major cost and energy loss in the sugar industries are the consumption of steam. The main challenging objective in the sugar industry is to reduce the steam consumption. Most of the sugar industries in Ethiopia are using rising film calendria type multiple effect evaporators (Robert’s type evaporator) which are simple, robust, and easy to operate but are susceptible to scaling and require periodic cleaning. The scaling highly reduces the heat transfer, which make the multi effect evaporator to consume more amount of steam. This research work suggests that the rising film multi effect evaporator can be replaced by some radial type multi effect evaporator, which can eliminate the disadvantaged caused by the rising film evaporator. This replacement modification can reduce the steam consumption in the process. The design modifications are done for the large capacity of 4000 TCD (tones cane per day). This novel design approach shows that the steam economy can be enhanced in the large scale sugar industries of Ethiopia Keywords: Steam economy, steam consumption, sugar industries, evaporators, design modification, multi effect evaporator, rising film evaporator, radial type evaporator, Robert‟s evaporator . 1. Introduction A. Evaporation The objective of evaporation is to concentrate a solution consisting of a non-volatile solute and a volatile solvent. In the overwhelming majority of evaporations the solvent is water. Evaporation differs from drying in that the residue is a liquid sometimes a highly viscous one rather than a solid; it differs from distillation in that the vapor usually is a single component, and even when the vapor is a mixture, no attempt is made in the evaporation step to separate the vapor into fractions; it differs from in that the emphasis is placed on concentrating a solution rather than forming and building crystals. Normally in evaporation the thick liquor is the valuable product and the vapor is condensed and discarded. B. Liquid characteristics The practical solution of an evaporation problem is profoundly affected by the character of the liquor to be evaporated. It is the wide variation in liquor to be concentrated. Some of the most important properties of evaporating liquids are as follows: Concentration: Although the thin liquor fed to an evaporator may be sufficiently dilute to have many of the physical properties of water, as the concentration increases, the solution becomes more and more individualistic. The density and viscosity increase with solid content until either the solution becomes saturated or the liquor becomes sluggish for adequate heat transfer. Continued boiling of a saturated solution causes crystals to form; these must be removed or the tubes clog. The boiling point of a solution may also rise considerably as the solid content increases, so that the boiling temperature of a concentrated solution may be much higher than that of water at the same pressure. Foaming: Some materials, especially organic substances, foam during vaporization. Stable foam accompanies the vapor out of the evaporator, causing heavy entrainment. In extreme cases the entire mass of liquid may boil over into the vapor outlet and be lost. Temperature sensitivity: Many fine chemicals, pharmaceutical products and foods are damaged when heated to moderate temperatures for relatively short times. In concentrating such materials special techniques are needed to reduce both the temperature of the liquid and the time of heating. Scale: Some solutions deposit scale on the heating surfaces. The overall coefficient then steadily diminishes, until the evaporator must be shut down and the tubes cleaned. When the scale is hard and insoluble, the cleaning is difficult and expensive.