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综合考虑延迟焦化装置换热实际情况,构建延迟焦化换热网络超结构。在混合整数非线性模型的基础上,通过设定不分流等假设对模型进行简化,建立了设备投资和公用工程费用权衡的数学模型。并给出了在数学规划软件MATLAB上实现模型快速求解的算法。利用枚举迭代法消除整数变量,实现混合整数非线性问题简化为非线性规划问题,大大降低了模型的求解难度,且求解得到的总费用更小。2个案例的运算结果显示,本文模型相比同步综合的混合整数非线性规划模型,年度总费用分别降低0.05%(7万元/年)和3.8%(587万元/年)。充分体现所提出的基于枚举迭代方法的NLP模型具有一定的实际应用价值。
Considering the actual situation of delayed coking unit heat exchange, a delayed coking heat exchanger network superstructure is constructed. Based on the mixed integer non-linear model, the model is simplified by setting the assumption of undivided flow, and a mathematical model of the trade-off between equipment investment and utility cost is established. And gives the algorithm to solve the model quickly in mathematic programming software MATLAB. Eliminating integer variables by using enumeration iteration method can reduce the mixed integer non-linear problem to a nonlinear programming problem, which greatly reduces the difficulty of solving the model, and solves the total cost less. The results of two cases show that the total annual cost of this model is reduced by 0.05% (70,000 yuan / year) and 3.8% (5.87 million yuan / year) respectively compared to the mixed integer nonlinear programming model with simultaneous synthesis. The full realization of the proposed NLP model based on enumeration iteration has some practical value.