Energy Efficiency Analysis Using Pinch Technology: A Case Study of Orbit Chemicals Industry

Abstract

The rising cost of fossil fuels and their negative impact to the environment has made it necessary for manufacturing industry to reduce energy consumption. Energy audits are commonly used to improve energy efficiency. However, the audits do not usually involve in-depth analysis of design features for optimum energy use. Pinch technology analysis, which involves heat exchanger design and retrofits, is increasingly being used to optimize energy utilization especially in thermo-chemical industries. Various pinch analysis studies have been conducted in different manufacturing and processing plants. However, there is no published literature about pinch analysis studies in the sulphonation process. Presented in this paper is the application of the pinch technology analysis to a sulphonation process at Orbit Chemical industries-Nairobi. The aim was to design a heat exchanger network retrofit for energy use reduction in the sulphonation process and to develop an investment appraisal for the design. The sulphonation plant studied consisted of 11 process streams. 3 streams went through heating processes and 8 streams went through cooling processes. The heating streams involved melting sulphur and raising its temperature to 160°C and generating steam at two temperatures 203°C and 160°C. The cooling streams involved cooling of air The heat exchanger network design resulted into a retrofit of 7 heat exchangers. If the retrofit could be implemented, the required external heating load could be reduced from 2.772 MW to 2.456 MW and the external cooling load from 0.329 MW to 0.014 MW. The recoverable heat was found to be 0.316 MW with estimated saving of 11.4 %. The annual savings for this design were KShs 3 132 093. The cost of retrofit was estimated at a current cost of KShs 49 275 540 with a simple payback period of 14 years.