69 - Application of AE technique and thermography for assessment of sludge volume inside crude oil storage tanks.

When crude oil is stored in large tanks, invariably high-molecular-weight organic sediments (paraffin) are deposited but the resulting sediments contains also solid particles (sand, silt, corrosion products, etc.) and also water. After some period of in-service of tank, these deposits build up to form a sludge, which causes a reduction in the storage capacity. These high in hydrocarbons a valuable raw material could be proper recovered and recycled back to the refining process. Therefore, it is significant to know the sludge characteristics shape and volume to define the best form of treatment (maintenance of tank for control of level of sludge) and removal method (in case of out of service and opening of tank). The knowledge about volume and shape of such sludge inside tanks is important for user of tank farm due to a reasons such as: maintenance of storage tanks and control/monitoring of level of sludge inside them, when conventional treatments are used to remove crude oil sludge, there is a potential for high environmental impact, so the choose of the method of cleaning is very essential, most of design of tanks is with floating roofs, what in case when inside tank is high level of sludge could cause problems and/or damage of roof for low level stored product. In this paper are presented AE and thermography techniques for assess of level, volume and shape of sludge inside storage tank. Thermography method is used to assess the level of sludge (heights) along the storage tank shell. AE technique is used in this case in different way than normally purposes. There is used specific layout of sensors on the wall and roof of the tank. The sensors generate of AE pulses according to established algorithm, which allows to record AE signals were caused the waves propagation and waves reflection (including from sludge) in storage product between sensors. Under measured differences in time of wave propagation are evaluated heights of sludge in various points inside on the bottom of tank. In 2017 Office of Technical Inspection (UDT) opened the project to develop a system for assessing of the level, volume and shape of sludge inside crude oil storage tanks, using AE technique and thermography. As part of the project, UDT has started cooperation with company PERN S.A. the national and regional leader in oil logistics. [ABSTRACT FROM AUTHOR]