Product mix and its optimisation in a paper mill according to the profitability computation of process measurements

Conventionally, the calculation of the product profitability in the paper mills has been made according to a standard recipe, i.e., based on experience that comes from the knowledge and understanding of the process, however, not according to the actual process measurement data, which has been seen too inaccurate so far. We studied this issue by using, among other relevant variables, flow and consistency measurements of the raw materials. By applying a standard recipe, a consumption calculation is made according to assumed raw material percentages, but, instead, we estimated them on the basis of process measurements data, such as flow and consistency. To consider product profitability, the raw material consumption is first calculated and then the mutual profitability of products and ultimately the product mix are estimated noting production and sales limits. In order to optimise the product mix, which corresponds to the division of production into different products desired, we introduced a heuristic model which is simpler and easier to control than a linear model. On the basis of the results, we can discredit the belief that guessing by using the standard recipe could yield a better accuracy than using process measurements.