【作者】 徐猛；

【导师】 李士雨；

【作者基本信息】 天津大学 ， 化学工程， 2007， 硕士

【摘要】 人口增长,能源危机,是当今世界的两大主题,节能降耗已是大势所趋。木糖在我国已经有四十多年的生产经验,技术上达到了世界水平,已是世界木糖生产和出口大国。但是,目前我国木糖生产的工艺流程中存在的一个主要问题就是蒸汽耗用量太大,能量没有充分的循环利用。因此,生成换热网络,并进行优化,最大限度的回收热量,意义重大。本文围绕这一主题,以某木糖生产厂家的工艺流程为背景,开展了如下的工作:1.利用夹点技术,对整个生产系统进行用能诊断,发现该生产过程对热量并没有充分利用,没有形成换热网络,造成了热量的巨大浪费。本文根据虚拟温度法计算出各个流股的传热温差,做出温-焓图,确定出了能量回收系统中“夹点”的位置,做出了过程的组合曲线和总组合曲线,依据夹点法设计规则,设计流股的匹配,合成出了具有最大能量回收特征的换热网络。本文还进行了换热设备的选择,以及合成换热网络前后公用工程耗量和费用的计算。2.以热力学原理为基础建立了数学模型,对整个木糖生产工程的换热网络进行了模拟,最终确定了年产5000吨木糖生产工艺的换热网络的数学模型,以及各个换热器进出流股的温度、物流流率等数据,为现场换热网络的优化奠定了基础。3.以灵敏度系数为基础,利用建立的数学模型,对木糖生产的换热网络进行灵敏度分析,找出了最佳的调节变量和更改参数,并在原换热网络的基础上设置了控制旁路,确定了调节变量的最大值和更改参数的增加值。在确定的干扰范围内可以对换热网络进行调节,满足所需的换热温度,提高了换热网络的柔性,达到所需工艺要求。通过本文的工作证明,利用夹点分析技术,指导木糖生产工艺过程的换热网络的合成及优化,利用灵敏度分析法,指导换热网络的优化控制设计,具有明显的优势,可以大大降低生产成本,同时填补在木糖生产技术方面能源节约的空白。更多还原

【Abstract】 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.更多还原