Development of a three-step hierarchical screening matrix to optimize inherently safety design index and inherently safety design cost (A case study in Acetic acid production process)

Application of inherently safety principle in the early phase of the design process is very efficient, as this approach is an economic and high efficiency method. While a complete information is not available in the initial phases of the process, the use of valid index to evaluate inherently safety can be efficient. In this case, the best route to design safer process can be selected by comparing the quantitative results.
Material and The comprehensive index to evaluate the inherently safety design (ISD) and cost evaluation of the implementing inherently safety design (ISDC) were studied using a three-step hierarchical matrix screening in this research. Utilizing the proposed inherently safety index, Acetic acid production process and cost resulting from ISD were evaluated. Dimensions of the Matrix for ISD and ISDC included: 1) quadrature inherently safety design vector, 2) location vector of inherently safety design and 3) quantity parameter vector of inherently safety design.
In order to optimize the implementation of inherently safety design and its cost, three hypotheses were used. From them, the idea of using two processes with half capacity and also using 50% Methanol were selected as a design with the highest level of inherently safety and a design with the lowest-cost process, respectively.
In these evalustions the total score for the assumptions of the inherently safety index 1, 2 and 3, were 55,70 and 135, respectively. And the total cost assumptions 1, 2 and 3, have been estimated 858,000, 746,000 and 803,000 US dollars, respectively. Therefore, this tool could show the impact of various scenarios in inherently safety design and also the contrast between the four principles of ISD and its impact on safety and cost factors can be analyzed using an alternative system supplier of methanol.