Energy Integration of Kero Hydrotreating Unit, A Case Study of Nigerian Refinery

Abstract

Kero hydrotreating unit being an integral part of the refinery system has been characterized by heat leaks, heat losses and inefficiencies in the heat transfer processes. This has necessitated the investigation into analysis of the current energy configuration to curb this menace and to proffer solution which would lead to efficient utilization of energy. Application of Pinch technology to kero hydrotreating unit heat exchanger network is presented with an optimum minimum approach temperature of 2.5°C to determine the energy target. This was achieved via the development of composite and grand composite curves for the kero hydrotreating unit process. The Pinch point temperature was found to be 544°C, with the utility targets for the minimum approach temperature being 7491.9 kW and 8259.62 kW for hot and cold utilities respectively, leading to energy savings of 34.33% and 32.17%. The percentage energy savings reported is as a result of the re-use of the cold or hot process streams before being sent back to the power plant or the trim coolers. Pinch analysis as an energy integration technique is proven to save more energy and utility cost than the traditional energy technique currently being used in the unit. The energy integration of the refinery kero hydrotreating unit using Pinch analysis did not only save energy and utility cost but showed significant improvement and exposed the inefficiencies of the traditional design approach. Keywords: Pinch analysis; Kero hydrotreating unit; Energy target; Heat integration Introduction Нe ability of any Nation to survive economically depends on its capacity to produce and manage sufficient supplies of low cost, safe energy and raw materials [1]. Worldwide consumption of limited fossil fuel resources is increasing with projections in this trend signifying that unless an efficient strategy is put in place, the world will soon be short in supply of energy. On the strategic statement of the energy sector of Nigeria vision 2020, it is necessary for the country to embark on energy conservation and efficiency initiatives which will require industries to move to energy saving equipment and utilities for reduction in total power demand by using technologies which ensure optimum energy utilization and integration. Pinch technology is a complete methodology derived from simple scientific principles. It allows the design of new plants with reduced energy and capital costs as well as where the existing processes require modification to improve performance [2]. More so, Pinch approach enables calculation of energy and utility targets by simple analysis of the process data, thus, an opportunity to design a new system or modification of existing system before embarking on actual implementation [3]. Pinch technology, when applied with imagination, can aUˆU´ect reactor design, separator design and the overall process optimization in any plant. But its application has proven that it can address problems beyond what energy conservation principles can resolve, as well as to solve problems as diverse as improving effluent quality, reducing emission, increasing product yield