One-step Integration Of Complex Heat Exchanger Network System And Utility System

The energy problem has been more and more serious as the economy goes on. But the process industry has still had the problem that energy consumption was too high. And at the same time the process industry has became more and more complex. So the traditional energy conservation method that based on element equipment is not fit for the new condition. The energy conservation method has turned to system energy conservation. To fit for this condition, this paper introduces a one-step integration of complex structure heat exchanger network system and utility system method. The paper introduces three models:(1) Building a mathematic model of heat exchanger network that based on temperature interval. The model used 0/1 variable to describe the construction of the network (considering non-isothermal mixing, splitting and allowed multiple heat exchangers between streams). Comparing to the former model, this model has no construction assumption. And it is basing on MILP, compare to the MINLP model. This model could give the exact solution.(2) Building a mathematic model of utilities system. This model using a new boiler efficiency formula and piecewise linear model of steam turbine formula that makes the total mathematic model based on MILP. Comparing to formerly model, this model not only has the characteristic of other MILP model, but also more exactly.(3) Building a mathematic model of process system that the parameters of the process engineering subsystem is fixed. This model is consisted of the heat exchanger network model and the utilities model introduced before. The most important characteristic of this model is one-step integration. And because the subsystems were basing on MILP, the total model is also basing on MILP. That makes the model having exact solution and high efficient of solution.