具有多级中间水道的循环冷却水系统优化研究

发布时间：2018-04-22 19:34

  本文选题：循环冷却水系统 + 优化　； 参考：《青岛科技大学》2017年硕士论文

【摘要】：循环冷却水系统在工业应用中具有较大的节水、节能潜力。而目前循环冷却水的研究方向主要集中在系统的节水或节能、冷却塔模型方面。本文结合以往研究成果,提出设置多级中间水道对循环冷却水系统进行优化,并以此为前提建立考虑水冷器、冷却塔等装置的循环冷却水系统的优化模型,从而确定循环冷却水系统的优化设计方案,主要研究内容如下:首先,通过对当前循环冷却水系统水冷器网络优化方法的对比和分析,本文在水夹点分析的基础上提出多级中间水道的循环冷却水优化方法,该方法能够明显提高冷却水的返塔水温,从而减少系统的循环冷却水量。文中同时总结出水冷器网络置入多级中间水道的设计步骤,并利用实例验证了通过设置中间水道的方法可将循环水量减少60%,证明了该方法的有效性。其次,本文分析了冷却塔性能的评价指标。并利用冷却塔模型对冷却塔的性能进行评价,实例计算表明,当循环冷却水系统水冷器网络中置入多级中间水道后,由于进塔水温升高和循环水量减少,引起冷却塔进出口温差加大、冷却极限接近度减小、冷却塔的效率系数得到有效提升,表明了加入中间水道后对冷却塔性能的提升具有重要作用,可以大大节省设备投资。另外,本文以操作费用和设备费用之和(即总费用)为目标函数建立数学模型,其中,设备费用主要考虑冷却塔的设备投资和以换热面积表示的水冷器设备费用,操作费用主要考虑系统运行过程中循环水泵的耗电费用、补充新鲜水费用及投加药剂费用。采用非线性规划方法进行求解。并在此基础研究了出塔水温对目标函数的影响规律,确定了最佳出塔水温,使得系统运行1年的总费用最少。最后,本文以某厂年产15万吨TDI(甲苯二异氰酸酯)部分装置为工程实例进行验证,优化其系统结构配置和操作参数。与之前水冷器并联连接相比,(1)优化后,水冷器网络采用具有二级中间水道的结构配置,循环水量降低81.3%;(2)优化后,冷却塔性能有所提升,其中冷却水进出塔温差增大387.3%,冷却极限接近度降低60%,冷却塔效率系数升高61%;(3)优化后,系统的最佳出塔水温为27℃,比优化前降低了3℃,此时虽然系统的设备费用升高了30.2%,但操作费用降低了81.3%,总费用降低了73.3%。
[Abstract]:Circulating cooling water system has great water saving and energy saving potential in industrial application. At present, the research direction of circulating cooling water is mainly water saving or energy saving, cooling tower model. Combined with the previous research results, this paper puts forward the optimization of circulating cooling water system by setting up multi-stage intermediate waterways, and establishes the optimization model of circulating cooling water system considering water cooler, cooling tower and so on. The main research contents are as follows: firstly, through the comparison and analysis of the network optimization methods of water cooler in the current circulating cooling water system, Based on the analysis of water pinch point, this paper presents an optimization method for circulating cooling water in multistage intermediate waterways. This method can obviously increase the water temperature of cooling water back to the tower and thus reduce the circulating cooling water quantity of the system. At the same time, the design steps of the water cooler network are summarized in this paper, and the effectiveness of this method is proved by using an example to verify that the circulating water volume can be reduced by 60% by setting the intermediate channel. Secondly, the performance evaluation index of cooling tower is analyzed. The performance of the cooling tower is evaluated by using the cooling tower model. The example calculation shows that when the multi-stage intermediate channel is placed in the water cooler network of the circulating cooling water system, the water temperature of the inlet tower increases and the circulating water quantity decreases. As a result, the inlet and outlet temperature difference of cooling tower is increased, the cooling limit approach is reduced, and the efficiency coefficient of cooling tower is effectively raised, which indicates that adding intermediate channel plays an important role in improving the performance of cooling tower and can greatly save equipment investment. In addition, the mathematical model is established with the sum of operation cost and equipment cost (that is, total cost) as the objective function, in which the equipment cost mainly considers the equipment investment of cooling tower and the equipment cost of water cooler expressed by heat exchange area. The operating cost mainly includes the power consumption cost of circulating water pump, the cost of fresh water and the charge of reagents during the operation of the system. The nonlinear programming method is used to solve the problem. On this basis, the influence of water temperature on the objective function is studied, and the optimum water temperature is determined, so that the total cost of the system running for one year is the least. Finally, a project example of a plant with an annual output of 150000 tons of TDI (toluene diisocyanate) is given to optimize the system configuration and operation parameters. Compared with the previous parallel connection of the water cooler, the cooling tower performance has been improved after the optimization of the water cooler network with the configuration of a two-stage intermediate waterway and the reduction of the circulating water quantity by 81.33 / 2). After the cooling water inlet and outlet tower temperature difference increases 387.3%, the cooling limit approach degree decreases 60%, the cooling tower efficiency coefficient increases 61% and the cooling tower efficiency coefficient is increased, the optimum water temperature of the system is 27 鈩，

本文编号：1788608