Optimization of Integrated Batch Mixing and Continuous Flow in Glass Tube & Fluorescent Lamp

This paper deals with production planning of in-series continuous flow, and discrete production plants. The work is applied to glass and fluorescent lamp industry, where raw materials are mixed in batches, charged to a continuous furnace to produce glass tubes, and then assembled into discrete lamps. A non-linear programming model was formulated from the raw material mixing stage till the production of fluorescent lamps. Using the model, the amount of each raw material can be obtained at minimum cost, while satisfying the desired properties of the produced glass. The model also provides the optimum lamp production amounts, inventory levels, and the glass pull rate from the furnace, which determines the production amounts of glass tubes. An important factor in the continuous flow process is the amount of broken glass (cullet) added in the furnace, which has an impact of raw material cost and natural gas consumption. In order to solve the model, separable programming methods and linear approximations were used to transform the non-linear terms. Results are validated versus actual production data from local Glass & Lamp factories, and the model proved to be an efficient tool of integrating the whole process at minimum cost.