炼油企业循环水用水网络优化技术与应用

The Technology for Optimizing Circulating Water Network of Refineries and Its Application

循环冷却水系统是石化行业重要的公用工程,其用水量占工业用水量的80%左右,是石油化工领域用水量最大的系统。循环水系统节水状况的好坏,将严重影响整个工业水系统的节水程度。针对炼油企业循环水系统能耗大、运行不经济等实际问题,分析了炼油企业循环水用水网络优化的影响因素,根据循环冷却水系统的超结构建模原理,以循环水用量最小为目标,综合考虑水流量平衡、热量平衡、水冷器进出口温度、水冷器温差、整数变量、现场实际条件等因素,建立循环水用水网络优化的数学模型,并采用优化建模工具Lingo建模求解,以获得循环水量最小、网络结构简单的循环水用水网络。以某炼油企业蜡油加氢装置循环水系统为实例,验证模型的可靠性。分析结果表明,优化模型充分考虑了蜡油加氢装置循环水用水网络的特点,获得了循环水用量最少且网络结构简单的循环水用水网络,有效降低了循环水系统的运行成本。优化前后该装置各水冷器用水量对比显示,循环水系统优化后,每小时节约循环水152.09t,占现行冷却水总量的40.9%,按循环水价格0.3元/t计算,每年节约水费39.97万元。

The circulating cooling water system is an important utility of the petrochemical industry.Water used by this system represents about 80% of the industry＇s total water consumption for industrial use,making the system the largest water consumer of the petroleum and chemical sector.The water-saving efficiency of the circulating water system greatly affects the water-saving efficiency of the entire industrial water system.In order to find a solution to the problems with the circulating water system of a refinery,such as high energy consumption and high operating cost ,this article analyzes the factors affecting the optimization of a refinery＇s circulating water network.Based on the superstructure modeling mechanism of circulating cooling water systems and with minimizing circulating water use as the target,researchers developed a mathematical model to opti- mize the circulating water network ,having regard to water flow balance ,heat balance ,temperatures at the in- lets and outlets of water coolers,temperature differences of water c0olers,integer variable and actual field conditions.The optimized modeling tool Lingo was used in order to design a circulating water network with the lowest possible volume of circulating water and a simple structure.They tested the reliability of the model using the circulating water system of a paraffin wax hydrogenation unit of a refining company for example. Analysis shows that the model has given full consideration to the characteristics of circulating water networks of paraffin wax hydrogenation units and helped develop a circulating water system with the lowest possible volume of circulating water and a simple network structure ,resulting in a significant drop in the cost of oper- ating the circulating water system.A comparison between the water use of water coolers of the unit before and after the optimization shows that after the optimization,the circulating water system＇s circulating water use dropped by about 152.09t per hour,which represents 40.9% of current total volume of cooling water.As- suming the price of circulating water is 0.3 yuan per ton,annual savings of water bills will reach 399,700 yuan.