Sustainability Improvement of Kazakh Chemical Industry via Process Integration: A Case Study of Calcium Chloride Production

Abstract

This work presents the analysis of the calcium chloride concentration unit to reduce energy consumption and harmful emissions. The concentration of the calcium chloride in the raw materials is 14 % (mass) and a concentrated solution has 35 % of CaCl₂. Process Integration techniques were used for the analysis of the existing process to identify bottlenecks and disadvantages. A Pinch approach was executed to get real energy targets, energy gap and possible ways for process update. The authors proposed the solution for the process improvement using traced Grid Diagram and detailed simulation of the parameters of heat exchangers and evaporation units to get a feasible and economically beneficial retrofit. The representative case study of a Kazakh chemical factory was presented. There are some barriers to the development of the profitable and feasible solution, e.g. process constraints and limited performance of existing equipment. It forces developing a local methodology to apply the case study in an appropriate and most profitable way. The energy consumption of the inspected unit is 25 % higher than the target value. Nevertheless, the 1^st feasible retrofit case with a detailed simulation of heat exchanger network parameters has only 17 % less energy consumption but, at the same time, the improved operating conditions of the evaporation unit were achieved. The 2^nd retrofit option reduces the energy consumption by 22 % and more complicated network with additional operation changes was proposed. The results of this work may be used for the energy saving retrofit of the industrial evaporation units and decreasing the environmental impact of the chemical industry in Kazakhstan.