Study of energy use in eastern refinery limited and conservation possibilities

Abstract

This thesis discusses the energy use in Eastern Refinery Limited and the possibilities of energy conservation. It illustrates various processes., equipment and system oriented approach of energy conservation The objdtive of energy conservation can be achieved by auditing the energy consumed in every process unit and then to save energy, various steps are to be taken including designing more efficient and compact process units like heat exchanger, furnace etc, revamping existing equipment or overall BMRE (Balancing, Modernization and Rehabilitation) This study on energy use and conservation possibilities was carried out in Eastern Refinery Ltd. (ERL), the only petroleum refinery plant in Bangladesh. ERL has five processing unit; the study was kept limited to Crude Distillation Unit, the main unit of the refinery plant. Eastern Refinery Ltd. was designed in the mid-60's and went on strcam in 1968. At its early stage energy conservation was not so stringent as it is now in a refinery of 2001. ERL has taken necessary steps to improve the plant's efficiency and to conserve energy. ERL is now processing 1.3 - 1.4 million MT of crude oil per annum, as against its installed capacity of 1 5 million tons per year. Furnace is the major consumer of energy, usually obtained by burning hydrocarbon fueL It is estimated that total energy consumption of ERL is about 60.54 MMkcal per hour of which distillation furnace alone is consuming near about 28,62 MMkcaVhr (47.27 %), It has been found that, the furnace is running with a thermal efficiency about 65 % and operating with about 77 % excess air which is much higher than the designed value(40%). 1 - 2 % improvement in thermal efficicncy is possible by reducing excess air to the furnace only and through proper monitoring. It has been found that 1% improvement in thermal efficiency in the furnace will result in energy saving of around 3256 MMkcal per year and savings in terms of money around T1:.22,34, 104.00 per year. Energy consumption in ERL per barrel of Crude oil processing is about 0.05 MM kcal, The overall processing expense of Crude oil is increasing every year. In 1990- 91 financial years it was Tk.32.88 per Barrel and in the year 1999-2000 it increased vi; to Tk 58 70 per Barrel. About 4,99 MMkcal heat is wasted to cooling water during cooling products from process unit before tramfemng to storage tank. Heat exchanger can be placed before LGO and Residue water cooler, to save heal energy of about 3.99MM kcal 1Itr. A reasonable amount of energy can be saved by increasing flashing rate of crude oil in flashing dlllm before feeding to furnace, to avoid heating the same in the furnace.