Integrated Optimization Of Hot And Cold Utilities And Heat Exchanger Network

Energy is the motive force of human development. As the needs of the development, industrial enterprise is also faced with higher water-saving and energy-saving requirements. It becomes more important how to improve the energy-consuming and water-consuming efficiency of each industrial enterprise. The energy consumption of steam system which accounts for the proportion of the total energy consumption of industrial enterprise is very high. First of all, steam system should be optimized in order to enhance the energy-using efficiency of the enterprise. Heat exchanger network is an important form in the process of waste heat recovery. As one of the heat source of external utilities, process steam heating network takes advantage of waste heat of steam system and has big effect on the total energy-using efficiency of enterprises. As the blood of industrial enterprise, cooling water consumption is more than70%of the total water consumption of industry. So cooling water system cannot be ignored in order to improve the efficiency of water saving. This article researches the connection between steam system, steam heating network and cooling water system, in order to find a way to integrated optimization of the three systems to achieve the goal of energy saving and water saving of industrial enterprise.Firstly, this paper builds the off-design models for the boiler, steam turbine and so on. Besides, this paper takes the fuel consumption as the optimization goal and uses the method of programming optimization in order to get the optimal operation parameters of the system under the condition of meet the demand of electricity and heat.Then, this paper establishes the steam heating network model based on pinch analysis and puts forward the integrated optimization process of steam heating network and steam system. Besides, this article also takes an actual steam system of chemical plant to verify the validity of the model and achieves the effect of energy saving and water saving.This paper takes the steam heating network and original heat exchanger network together as a new heat exchanger network. This method can break the limits on the temperature when heat transfer ends and led the effect of energy saving and water saving better. After that the method considers the cost of the whole heat exchanger network and reduce the cost of the heat exchanger network through combine the heat exchangers and energy relaxation method.Finally, this paper establishes the cooling water system model, considers the effect of steam system operating conditions on cooling water volume in condenser and puts together the cooling water of condensing steam turbine and the cooling water in cooling process of general heat exchanger network. This method combines the water system into the original parallel network structure and changes the original cooling water network in order to achieve the effect of water saving. Through an actual case, steam system, steam heating network and cooling water system are put together and are optimized by optimization method. Through this method, energy and water both be saved.