الفهرس | Only 14 pages are availabe for public view |
Abstract Abstract Scales in sugar industry considered as one of the huge problems which still faced the development of the industry. This thesis conducted to overcome two of the scales deposition problems. First one is the scales which deposited on the surfaces of evaporator tubes, these scales were accumulated on the internal surface of the evaporator tubes forming an insulating layer that reduces heat exchange between juice and steam. This requires other procedures such as stopping the evaporators, cleaning and removing the sediment, and all these steps obstruct the industrial process. Our new approach to overcome this problem depends upon minimizing the problem in its source. That was carried through a new method of cane juice purification, which targeting to obtain a clear juice without any sulfur content, and also with the lowest residual of calcium, besides other good specifications. In this method a mixture of hydrogen peroxide and calcium hydroxide was used to treat an acidified mixed juice, then the treated juice subjected to flotation clarification, depending upon the internal chemical flotation phenomena which occurred in case of adding a mixture of hydrogen peroxide and calcium hydroxide to the raw cane juice. In this point, work was done by testing the optimum conditions to cause flotation, like pH, temperature, the way of addition, additives. But the suitable conditions for flotation are not satisfactory to obtain a clear juice with good specifications. So the optimum conditions to obtain a clear juice with a good specification was studies. All these last conditions were determined in a batch laboratory work. The net results of the batch trials were used in contentious trials in a half industrial plant, and the final conditions and results were defined. Results show very positive indicators correspond to the target, that the clear juice not only contain a small amount of calcium and without any sulfur content, but also has a higher content of sucrose and less amount of ashes. Comparing the new method results with the corresponding results of the traditional methods used in the factories show the technical benefits. Also a financial feasibility study was conducted and compare them with that of traditional purification method, that to cover the subject from all respects. Abstract iv In the second part of this thesis, a problem of scale deposition on the central juice tube of clarifiers was studied and solved. In this case, the tube was completely clogged with deposits, and due to the vertical position of the tube at the center of the clarifier, the traditional way of cleaning cannot be used. So we conduct using a new chemical reagent which success in cause fragmenting to the deposits. This reagent was a mixture of hydrogen peroxide and sodium hydroxide, which added in a defined rule, results were obtained around a period of days. The common factor in both of the two thesis parts is the advantage of Alkaline decomposition of hydrogen peroxide, which cause an evolution of singlet oxygen and activation energy. Alkali in the first case was calcium hydroxide which plays the main rule in juice purification, while in the second case alkali was sodium hydroxide, which the famous chemical cleaning agents in the field of evaporator scales cleaning. |