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Research Interests:
Large quantities of spent hydrodesulfurization (HDS) catalysts are available from petrochemical industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its vanadium... more
Large quantities of spent hydrodesulfurization (HDS) catalysts are available from petrochemical industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its vanadium concentration. Most of these catalysts are usually supported on alumina containing a variable percentage of elements such as nickel or molybdenum. Hence these catalysts contain environmentally critical, and economically valuable metals such as molyb denum, vanadium, and, nickel. In this paper, a spent HDS catalyst was treated with caustic soda solution. Parameters such as temperature, time, and NaOH solution concentration have been studied thoroughly, in order to settle the appropriate conditions for the maximum recovery of molybdenum and vanadium. Under the best leaching conditions (20 %w NaOH, room temperature, 2 h) about 95% recovery of Mo and V was achieved, and the recovery of nickel obtained was of 99% in the form of NiAlO4.
Research Interests:
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A simplified quantitative analysis methodology for the determination of required Safety Instrumented Systems (SIS) and the associated target Safety Integrity Levels (SIL) is presented. As prerequisites, the company policy for risk... more
A simplified quantitative analysis methodology for the determination of required Safety Instrumented Systems (SIS) and the associated target Safety Integrity Levels (SIL) is presented. As prerequisites, the company policy for risk acceptability and a hazard and operability (HAZOP) study are needed. A risk acceptability criterion for large commodity chemical, petrochemical, or refining companies is discussed. The methodology starts with the selection of high potential risk scenarios from the HAZOP study. Then the effectiveness of the relevant process safeguards is evaluated based on layers of protection analysis, to assess if there are adequate and sufficient safety protection layers in the chemical process, so that the actual risk of the process is at an acceptable level. The method allows the user to determine first if a SIS is required and then, what SIL is required for each function it performs. If a SIS already exists in the process, the methodology can be used to verify the required SIL for each safety instrumented function. © 2009 American Institute of Chemical Engineers Process Saf Prog 2010