Abstract:

The steam power system of the units in the refinery is usually designed and operated independently, which ignores the connection with the steam power system of the thermal power plant. Steam power system in thermal power plant is often optimized under fixed steam and power demand, ignoring the connection to the steam power system of the units. To achieve the overall optimization of the steam power system of the refinery, this paper proposed a method for synchronous optimization of steam power system for processing units and the thermal power plant operation. Firstly, the equipment model coefficients were obtained by using the design and operation data of the turbines and boilers of the thermal power plant, and steam power system constraints for the thermal power plant were established according to the existing structure. Then, based on design and operational flexibility of steam power system for units, the units were divided into three categories. The first category of units cannot adjust the steam and power demand, the second category of devices can adjust the steam demand by temperature and pressure reduction, and the third category of units cannot only adjust the steam demand by temperature and pressure reduction, but also adjust the steam and power demand through drive selections. The model parameters for turbines in units used the literature values, then established the steam power system constraints of the units by collecting data of steam and power demand of units. Finally, a coupling model is established through connection of steam and power between the thermal power plant and the units. The coupling model takes the annual cost as the objective function, which includes the operating cost of the thermal power plant and the annual investment cost of turbines and motors for units. Equipment load distribution plan of the thermal power plant and steam power system design plan of units is obtained through optimization. The feasibility of the synchronous optimization method is demonstrated through a calculation example. Compared with the independent optimization, the synchronous optimization reduces annual expenses by USD 4.51 million.

Key words: steam power system, operations, design, systems engineering, global optimization

摘要：

石化企业装置蒸汽动力系统通常独立设计和操作，忽视了与热电厂蒸汽动力系统的联系。热电厂蒸汽动力系统通常在固定的蒸汽和电力需求下进行优化，忽视了与装置蒸汽动力系统的联系。为实现石化企业蒸汽动力系统的全局优化，本文提出了用于装置蒸汽动力系统与热电厂运行同步优化的方法。首先使用热电厂透平和锅炉的设计及运行数据回归得到设备模型系数，依照现有结构建立热电厂蒸汽动力系统约束。然后以装置蒸汽动力系统设计和操作灵活性为区分，将装置分为三类：第一类装置蒸汽和电力需求无法调节；第二类装置可以通过减温减压调节蒸汽需求；第三类装置既可以通过减温减压调节蒸汽需求，也可以通过驱动选择调节热电需求。装置透平模型参数采用文献值，通过采集各类装置蒸汽和电力需求等数据建立装置蒸汽动力系统约束，最后通过热电厂与装置蒸汽和电力的连接关系建立耦合模型。耦合模型以年度费用为目标函数，其中包括热电厂运行费用以及装置透平和电机的年度投资费用，通过优化求解得到热电厂设备负荷分配方案以及装置蒸汽动力系统设计方案。通过算例论证了同步优化方法的可行性，与独立优化相比，同步优化降低年度费用451万美元。

关键词: 蒸汽动力系统, 运行, 设计, 系统工程, 整体优化