Synthesis And Optimization Of The Heat Exchanger Network Of Xylose Process

Population overflow and energy crisis are two topics of today's world, and energy conservation is of the tendency. China is one of the most important countries producing and export xylose in the world, which has had more than forty years'experience about producing xylose and our technology has reached the world advanced level. However, nowadays'our producing process has a main problem that the steam consumption is too much, and the energy is not completely used. So, designing and optimizing the heat exchanger network and maximizing the energy-saved are of great importance.Surrounding this subject, according to the background of technology the xylose producing, such work has been done:1.Using pinch technology to diagnose the energy-used conditions of the whole system, we explored that the energy was not completely used, and the heat exchanger network was not synthesized. As a result, mounts of heat was wasted. In this paper, we computed each stream's heat transfer temperature with the method of pseudo-temperature, obtained the T-H graph, confirmed the pinch position of energy system, and pictured composite curve and grand composite curve. According to pinch technology, devised matches of the streams, and synthesized the heat exchanger network with the character of maximum energy recovery. The types of heat exchangers were chose. The wastage and cost of utility loads were calculated before and after the heat exchanger network was synthesized.2.We built mathematical model and simulated the whole xylose producing process. Finally, we determined the mathematical model of heat exchanger network in the producing xylose process whose output was 5,000 ton per year, each heat exchanger's input and output streams'temperature,streams'flow rate and so on. The mathematical model established the foundation of the optimization of the locale heat exchanger network.3.On the basis of sensitivity coefficients and mathematical models, we analyzed the sensitivity of the heat exchanger network, found the optimal manipulated variables and the optimal retrofitted parameters, and set the control bypasses, and confirmed the maximum of manipulated variables and the increasing values of retrofitted parameters. The heat exchanger network could be accommodated in the certain extension, so it could arrive at the certain temperature and meet the technical requirements. The heat exchanger network's flexibility was improved.This paper proved that it had obvious predominance, that using pinch technology synthesized the heat exchanger network of xylose producing process, and that using analytical method of sensitivity guided design of heat exchanger network's optimizing control. It could fill the blank of saving energy in the area of xylose producing technology.