炼化一体化项目多个相互连接蒸汽动力系统设计优化

摘要/Abstract

摘要： 在炼化一体化项目中，有一个动力中心(CUS , centralized utility system)用来集成各生产装置蒸汽需求，还有两个分别位于炼厂和乙烯厂中的子蒸汽动力系统(SUSs, sub-utility systems)为工艺过程提供驱动力。SUSs的结构和操作条件会影响炼油和乙烯装置的蒸汽需求，因此很难确定CUS的蒸汽产量。为了探究CUS和SUSs间复杂的相互影响，本文提出了一个混合整数非线性规划模型(MINLP, mixed-integer nonlinear programming)，以实现多个相互连接蒸汽动力系统设计优化，从而降低系统年度总费用(TAC, total annualized cost)。本文还建立了一个包含CUS和SUSs厂间蒸汽连接管道的超结构，同时提出了一个更准确的复杂蒸汽透平模型。将本文建立的MINLP模型用于某新建炼化一体化项目。为探究蒸汽主管温度对系统结构和操作条件的影响，研究了两个不同场景下的案例。通过优化主管温度，使系统TAC降低了$2,700,000。从优化结果可知，本文建立的优化模型可以有效解决多个相互连接蒸汽动力系统设计优化问题。

关键词: MINLP模型, 多个相互连接蒸汽动力系统, 复杂蒸汽透平, 蒸汽主管温度

Abstract: In an integrated refinery and petrochemical, a centralized utility system (CUS) is generally introduced to integrate the steam demands for all production plants. However, two sub-utility systems (SUSs) locate inside alkene and refinery plants respectively to satisfy the mechanical power demands. Thus, it is difficult to determine the steam production of the CUS because the steam demands of alkene and refinery plants depend on the design and operation of SUSs. To explore the complicated interactions between the CUS and SUSs, we proposed a mixed-integer nonlinear programming (MINLP) model for the synthesis of multiple interconnected utility systems. An extended superstructure was suggested where contains multiple inter-plant connected steam pipe alternatives between the CUS and SUSs and from which the best combination can be identified by the optimization procedure. In SUSs, due to the deficit of steam generated from the process, the CUS needs to supply sufficient steam to the production plants through the final pipes when the plants start. Thus, constraints to select the pipe alternatives were constructed to guarantee that the final pipes can transport enough steam to compensate for the steam deficit. A simple but sufficient accurate model of the multiple extraction steam turbines was proposed to simplify the optimization routine. Then the proposed MINLP framework is applied to a new integrated refinery and petrochemical complex. Two scenarios are investigated in the case study to explore the effect of steam main temperatures on system configurations and operating parameters. In scenario 1 for the fixed main temperatures, the final inter-plant connected pipes between the CUS and SUSs can transport enough steam to compensate for the steam deficit when the alkene and refinery plants start, the TAC of which is $701.17 million. By optimizing the main temperatures, the TAC can be saved $2.7 million. From the results of the two scenarios, the feasibility and effectiveness of the proposed framework for the synthesis of multiple interconnected utility systems have been demonstrated.

Key words: MINLP model, multiple interconnected utility systems, complex steam turbines, steam main temperatures

白浩博李士雨王徐鹏刘昶. 炼化一体化项目多个相互连接蒸汽动力系统设计优化[J]. , 2020, 22(4): 126-136.

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