Gas Scheduling For Iron And Steel Industry Based On Universal Mole Flow

Energy consumption of iron and steel industry accounts for 10% of total industrial energy consumption. Energy costs of iron and steel interprises consist of 20% of its total production costs, while by-product gases of iron and steel plants can provide 30% to 40% of production energy consumption. By-product gases comprise blast furnace gas, coke oven gas and Id converter gas. Balance conditions of gas system of iron and steel plant should be influenced by generator processes, mixing stations and users. There are often situations in iron and steel plants that on one hand by-product gas is surplus and diffused; on the other hand some gas users would resort to supplementary energy for short of supply. Utilization of by-product gases would directly reflect energy utility level of iron and steel industry, and directly influence product costs. Optimization and scheduling of by-product gases is an effective approach to increase its utility efficiency in iron and steel industry.This paper models the gas pipe-network of iron and steel industry with weighted digraph model, with vertexes for processes and edges for pipelines. The concept of "universal mole flow" is deduced by Clapyron equation with by-product gas attribtes of flow rate, temperature and pressure. Based on the concept of universal mole flow, two sorts of vertex equations of pipe-network digraph model are deduces with universal mole flow balance and heat value balance. According to vertex equations and weight of each vertex, a sort of linear programming model is built for gas scheduling of iron and steel. This sort of scheduling model expresses flow rate balance and heat value optimization by vertex equations, and reflects scheduling rules and produce experiences by scheduling weights of vertexes.Based on this optimization model for gas scheduling, this paper designs the gas scheduling method of iron and steel industry, with event-driving strategy triggering scheduling proccess and with pipe-network digraph model orginizing modeling data. The pipe-network digraph comprises gas data of vertexes and connnection data. Scheduling strategy of this method is the so-called mixed strategy which synthezises the periodic strategy and the dynamic stategy. Having designed the scheduling flows of periodic events and dynamic events, the paper introduces program structure and flow of this scheduling method in detail, from three main processes of models converting, solving and results analyzing. Having realizing scheduling program, the paper demonstrates the effectiveness of this scheduling method with practical cases of certain iron and steel plant.This method of gas scheduling is mentally clear and scheduling model has simple structure which is easy to solve. Compared with scheduling methods based pricise mathmatical modles, this method possesses better adaptability and stability; compared with scheduling methods based on rules, this method is easier to control optimization direction and assess optimization level.