No.8 CASESTUDY
OVERVIEW This case study was for the cleaning of a crude oil surge tank and also for decontamination of a Tilting Plate Separator using Zyme-Flow® UN657 in both processes. CHALLENGES This was the first time Zyme-Flow® was used on site and it was thus regarded as a trial. Client concerns were a level of sludge/solids to a depth of 1m in the tank and the separator was also expected to contain a significant volume of sludge. NORM was also expected in both the tank and the separator. The client was seeking to improve performance and to reduce time taken over previous methods. PAST PROCEDURE Previous cleans were implemented using physical/ mechanical sludge removal after completion of a flushing procedure. This method was time consuming and gave variable results. DECON SOLUTION The Tank was cleaned using a two-stage process with circulation of Zyme-Flow® in diesel oil for 12 hours at ambient temperature, followed by circulation of an aqueous Zyme-Flow® solution for a further 12 hours, again at ambient temperature. Circulation was accomplished using a rotating spray nozzle inserted in a roof hatch with circulating pump suction taken from a low point outlet at base of the tank. This process enabled treatment of the sludge within the tank whilst also washing down the tank roof side and other internal surface. The tilting plate separator was decontaminated using a standard Vapour Phase process with steam injected into each of the four sections of the separator and Zyme-Flow® dosed immediately before splitting the steam supply into each of the sections. enquiries@denholm-macnamee.com Tel: + 44 (0) 1467 629 933 Tank& Vessel Decon TESTIMONIAL " Given the success of the project RSR are leaning towards the use of the Zyme-Flow system for other projects " Maintanance Manager
FLOTTAOIL TERMINAL
RESULTS The Tank and separator were both completed within the anticipated time frame. On opening the tank hatches site personnel took photos which are shown below and the client was extremely pleased with the result of the cleans. There were no solids remaining and no traces of NORM contamination remaining within the tank. The tilting plate separator was opened and found to be clear of H2S, LEL and oil. It was apparent on opening the vessel that the plastic filters within the vessel had collapsed at some point during the service life of the separator and these were found to be piled up at the bottom of the vessel. This had resulted in some sludge being trapped. Client personnel considered that this was an unforeseen problem and in no way reflected on the performance of the decontamination. On removal of the plastic debris the remaining sludge was easily and quickly hosed out of the separator. All other internal surfaces of the separator were found to be cleaned and decontaminated. CLIENT COMMENTS Denholm reduced the time that would have been spent on vessel entry & clean out, no hydrocarbon vapours or NORM was found reducing risk of entry. They dissolved the hydrocarbons and wax so reducing the waste by a considerable amount. The Terminal Superintendent and Manager has requested them to come back on site to survey 2 vessels for the Zyme-Flow® operation after the excellent result that was achieved during the cleanout of C321& D313. Processing was maintained for a period of 8 hours after which time the test results indicated that the vessel was free of H2S & LEL. The vessel was allowed to cool overnight before opening for inspection.
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