Patent EA-003659-B1 (EA)
Title: Method for cleaning an oil storage tank and device for implementing same
Inventor: WARTEL MIKE
IPC: B08B9/08
Filed: 1997-12-18
Abstract: 1. A process for recovering in suspension of sludge (3), which is formed, as a result of sedimentation, layer over the bottom of a storage tank (1), with floating cover (2), provided with a quantity of leg openings (4), uniformly distributed on the surface and allowing to fix the legs, able to support the cover (2), leaning on the bottom of the storage tank (Ib), when the level of crude oil in storage tank (1) become lower than the length (D) of legs, wherein: the level of crude oil in storage tank (1) is taken to distance L from highest level of sludge (3) on the bottom of storage tank (Ib), crude oil is pumped from the storage tank (1) with, at least, one pump (8) with the global production per hour which is equal to V/n, wherein V is volume, placed in storage tank (1) under the floating cover (2), the pumped crude oil is reintroduced in storage tank (1), supercharging by means of nozzles (5), installed in floating cover (2) instead of legs in leg sleeves and introduced in storage tank (1) vertically above the sludge (3), wherein each of mentioned nozzles (5) has under the floating cover a length less than L and being driven in axial rotation, wherein the lower tip is blanked off and provided with, at least, one jet over the sludge (3), stream (8a) being directed to the side of storage tank bottom (1b), and outflow face of jet or jets of the same nozzle (5) is quite small for the outflow pressure of stream of crude oil together with consumption making by one pump to ensure to creation turbulent volume around the nozzle (5), the procedure is going until the density of pumpable crude oil is equal to predefined value, which corresponds to almost full recovering of sludge (3) in suspension state, distance L being between 2 and 5 meters, n between 8 and 15, and nozzles are driven in rotation with speed of from 0.25 to 4 rpm. 2. Process according to claim 1, characterized in that the jet or jets of lower level of each nozzle (5) are placed on from 20 to 50 sm upper from the average sludge level (3). 3. Process according to claim 1 or 2, characterized in that on each nozzle (5) there are a lot of jets, distributed along the nozzle for the turbulent volume, formed by one nozzle (5) to cover a whole layer thickness of crude oil in storage tank (1). 4. A device for recovering in suspension of sludge (3), which is formed, as a result of sedimentation on the bottom of storage tank (1), with floating cover (2), closing crude oil, containing nozzles (5), with possibility of installing in a floating cover (2) instead of legs in leg sleeves and with introduction in storage tank (1) vertically above the sludge (3), wherein each of mentioned nozzles (5) are installed with the possibility of axial rotation and provided with several jets, placed on three levels in relation to the bottom of storage tank (Ib), the jet of middle level forming the stream, almost horizontal, the jets of lower level are directed to the bottom of tank, and jets of upper level are directed to the floating cover (2), wherein the lets of upper and lower level form streams, the legs being inclined to 50 degree -70 degree relative to legs of nozzle (5), bringing the jets. 5. Device according to claim 4, characterized in that each level of jets contains 2 diametrically opposite jets. 6. Device according to claim 4 or 5, characterized in that the pump or pumps (8), pumping crude oil from the tank are volume pumps. 7. Device according to claim 6, characterized in that it contains at least 2 pumps (8), before each at least one filter (9) is installed, and with following (12) behind each one, feeding p jets (5), wherein p is equal integer for all capacities of device.