DE1266267B - Method and device for removing oily deposits from the inner surfaces of container walls by washing the walls with a cleaning fluid - Google Patents

Description

Method and device for removing oily deposits from the Inner surfaces of container walls by washing the walls with a cleaning liquid The invention relates to a method and a device for removing oily deposits from the inner surfaces of container walls by washing the walls with a Cleaning fluid, the mixture of cleaning fluid and oily deposits is withdrawn from the container and separated again in a separating container.

In the known methods of this type, the dirty cleaning liquid pumped from the container to be cleaned directly into the separation container. Since the But liquid is unevenly obtained in the container to be cleaned, so results there is an uneven flow through the separation container, which causes the separation process is affected. If the cleaning liquid leaving the separation tank is used again immediately for further tank cleaning, this affects the uneven Inflow to the separation tank also has an adverse effect on tank cleaning.

The object of the invention is to ensure a fluctuating flow rate to be avoided in the separation tank.

The invention consists in that the mixture, before it enters the separating tank, is passed through an equalizing tank which converts a fluctuating flow rate into an essentially constant rate, in which the greater part of the mixture separates into an oily upper layer and an oily-aqueous intermediate layer , whereby coarser deposits settle as bottom sludge, while the finer separation of the oily mixture into oil and cleaning fluid takes place in the separation tank.

The advantage of the invention is that the switch-off container connected between the container to be cleaned and the separating container acts as a buffer from which, despite the fluctuating supply of the mixture from the container to be cleaned, the mixture can be passed into the separating container at a constant speed, so that a Trouble-free operation of the separation tank is guaranteed. A constant inflow of the cleaned cleaning liquid to the spray nozzle arrangement in the container to be cleaned is then also ensured. In addition, the expansion tank has the advantage that in it a rough separation of the mixture into an upper oil layer and an oily-aqueous intermediate layer takes place and bottom sludge settles, so that in the separating tank only a fine separation of the oily-aqueous mixture into oil and Cleaning fluid needs to take place. Furthermore, the expansion tank offers the advantage that chemicals that support the cleaning process can be mixed with the water in it. Finally, the expansion tank offers the possibility of degassing the mixture and heating it. It can also serve as a reservoir for the Recovered Oil. The pump, which draws the mixture from the container to be cleaned, does not need to be limited in its performance to the capacity of the separating container, since the equalizing container is able to absorb excess quantities.

The cleaning of the container and the separation of the mixture can be done in take place in a closed circuit that the cleaning liquid, the separated from the mixture of cleaning liquid and removed oily deposits is returned for the purpose of further tank cleaning.

The cleaning liquid advantageously contains water, in which a or more freely soluble electrolytes are included to the specific gravity adjust the aqueous phase according to the required separation.

When it comes to cleaning ship's tanks, it contains the cleaning fluid advantageously seawater. It can also be made entirely from lake water exist.

Separation or stratification of the components of the mixture occurs advantageously in the presence of a surfactant.

The method according to the invention is advantageous with one device carried out, which is characterized by means for supplying a cleaning liquid, speed at the location of the surfaces to be cleaned, means for centrifuging the cleaning liquid against the surfaces, an expansion tank for receiving the mixture of cleaning fluid and removed oily deposits that occur during the cleaning process Separation tank, which is in connection with the expansion tank and means for the Return of the cleaning liquid to the location of the surfaces to be cleaned for the purpose repeated hurling against these surfaces, with the relative volumes of the expansion tank and the separation vessel are such that the flow rate of the mixture from cleaning liquid and removed oily deposits into the separation container can be kept substantially constant regardless of the flow rate of the mixture in the expansion tank.

The separation tank advantageously consists of a cyclone separator, which has two units, namely a separation unit and a heating unit.

To avoid getting unwanted solids into the expansion tank and enter the separation tank, means for removing coarse solids are in the Flow line between the tank being washed and the surge tank intended.

Means are advantageously provided for drawing off oil that is separated off in the separating container and for introducing this oil into the compensating container, which in this way also serves as a reservoir for the recovered oil .

However, means can also be provided to draw off oil that separates in the upper part of the expansion tank and to guide it into an oil reservoir, into which the separated oil from the separation tank is also passed.

To clean the tank rooms of tankers during the empty journey the device is advantageously installed on the joint. The expansion tank can then be formed by a cargo tank or a coffer dam.

In the drawing, the subject matter of the invention is shown schematically and by way of example. It shows F i g. 1 shows a schematic representation of the device that can be used on board a ship, FIG . 2 shows a schematic representation of the device according to FIG. 1, installed in a ship, F i g. 3 shows a schematic representation of a second embodiment of the device, FIG. 4 the separation container according to FIG . 3.

In Fig. 1 , an expansion tank 1 is connected by a line 2 to the tank 3 to be cleaned. The bottom of the tank 3 which collects mixture of cleaning fluid and oily deposits is aspirated by a pump 4 from the tank 3 and conveyed through line 2 into the compensation tank. In line 2, a filter (not shown) is advantageously interposed between pump 4 and tank 3 , which filter retains coarse solids.

A separation tank, which consists of a heating unit 8 and a separation unit 9 , is connected to the lower part of the expansion tank 1 by a line 10 . A pump 13 in the line 10 draws the mixture from the expansion tank 1 via a suction cup 11 and first presses it into the heating unit 8, from which the heated mixture passed through the line 12 into the separating unit 9 in the heating unit 8 and the separating unit 9 oil rising to the surface can be returned through lines 16 and 17, valves 18 and 19 and a common line 20 to the diverting container 1 , which thus serves as a reservoir for the recovered oil . Vent lines 21 and 22 allow the recovered oil to be degassed.

In the funnel-shaped bottom of the heating unit 8, and the separating unit 9, collecting sludge may be withdrawn through lines 23 and 24th

A centrifugal device 25 is provided within the tank 3 to be cleaned, to which the cleaning liquid is fed by a pump 26 via a line 27 and 29 from the separation unit 9. A pressure gauge 31 and a thermometer 32 are connected to the line 29.

The power of the pump 26 must be adjusted so that the heating unit 8 and the separating unit 9 are never pumped empty. A vent line 33 and an overflow line 34, which leads back into the expansion tank 1 , are connected to the feed line 27 to the pump 26 .

As shown in FIG. 2, the heating unit 8 and the separating unit 9 are arranged on the ship's deck Angel in such a way that they are mostly below deck and only protrude with the upper end, which has the essential connections.

The heating unit 8 and the separating unit 9 are equipped with heating coils. The heating steam is introduced into the units through a line 35 and lines 36 and 37 and discharged again through discharge lines 40 and 41 equipped with float valves 42 and 43.

When the device is put into operation, the separating tank 8, 9 and the equalizing tank 1 are first filled with seawater, which is sucked into the system through a seawater tank 44 and a valve 45.

If chemicals are to be added to the seawater in order to improve tank cleaning, these are expediently introduced into the discharge container 1 through an opening to be provided in its upper part.

Once the separation tank and the equalization tank have been filled with seawater, the valve 45 is closed and the cycle begins. The cleaning liquid fed from the separating container 9 by the pump 26 of the centrifugal device 25 is thrown against the inner surfaces of the tank 3 to be cleaned, and the mixture of cleaning liquid and removed oil deposits from the bottom of the tank is fed by the pump 4 to the expansion tank 1 , in which the larger Part of the mixture is separated into an oily upper layer 46 and an oily-aqueous intermediate layer 47, with finer deposits settling on the bottom of the expansion tank 1.

The oily-aqueous layer is drawn off from the expansion tank 1 by means of the pump 13 and pressed into the heating unit 8. After heating, it is transferred from this through the line 12 into the separating container 9 . The circuit is closed when the cleaning liquid occurring in the separating container 9 is fed back to the centrifugal device 25 by the pump 26.

If the cleaning process requires more water than is available in the circuit, it is possible to pump additional water into the expansion tank 1. Excess cleaning fluid can be drawn off via the line 48 after opening the valve 49. The expansion tank and the separation tank can also be emptied into the sea via the line 48.

In the embodiment according to FIG. 3, the mixture of cleaning fluid and oily waste deposits from the bottom of zureinigenden tank 51 by the pump 52 via a conduit 78 and a filter 53 supplied to the surge tank 50th The filter 53 can also be arranged in front of the pump 52 . The liquid is drawn off from the lower part of the expansion tank 50 via the line 70 into the separating tank 54. If the separation tank is higher than the expansion tank, a pump is provided in the line 70 . As far as possible, this pump must not cause any turbulence or emulsification of the oil and water. A reservoir 55 is provided for the recovered oil , the lower end of which is connected to the upper end of the expansion tank 50 by a line 84, 85 . The upper part of the separation container 54 is also connected to the feed line 85 to the lower end of the reservoir 55 via a valve-controlled line 87 .

The reclaimed cleaning liquid is fed to the ejector device 57 in the tank 51 to be cleaned via a pump 58 , which is connected to the separation container 54 via a line 61. An emptying line 64 is also connected to the line 61 via a valve 63. Since the pump 58 has to generate the pressure required to spin the cleaning liquid out of the spinning device 57 against the inner wall of the tank 51 , a further pump should be connected upstream here if the distance between the pump 58 and the separating container 54 is large.

The lower part of the oil reservoir 55 is connected to the suction side of the pump 52 by a line 65 and a valve 66 , while an emptying line 68 is connected to the delivery side of this pump 52 via a valve 67. The pressure side of the pump 52 is also connected via a valve 69 to the connecting line 70 between the equalizing tank 50 and the separating tank 54. Bilge water can also be fed into this connecting line 70 via a valve 71.

A tank 72 is connected via a valve 73 to the line 62, 74, 77 connecting the pump 58 to the centrifugal device 57 , via which chemicals can be introduced into the cleaning water if they are not to be added to the expansion tank 50 .

When the device is put into operation, seawater is first sucked into the system by the pump 58 via a valve 75 and pressed via a valve-controlled branch line 76 from the pressure line of the pump 58 into the line 78 , which connects the pump 52 with the expansion tank 55 . The seawater consequently reaches the compensation tank 50 via the filter 53. The compensation tank is filled approximately three-quarters with seawater.

If the type of oily deposits in the tank 51 to be cleaned makes it necessary to use heated seawater, a heating coil is provided in the expansion tank 50 which enables the seawater to be heated to about 901.degree. If chemicals are to be added to the seawater, openings for introducing the same are provided in the compensation tank 50 for this purpose. In order to achieve a thorough solution and / or dispersion of the chemicals in the seawater, the contents of the expansion tank 50 are pumped back into the expansion tank 50 by the pump 58 with the valves 59, 79, 76 and 80 open.

At the beginning of the tank cleaning, the valve 76 ip of the branch line is closed and the cleaning liquid is drawn off from the separating container 54 and pumped to the centrifugal device 57. The mixture that accumulates at the bottom of the tank 51 to be cleaned is pumped into the expansion tank by the pump 52 and, with the valves 81, 82, 80, 59, 79 and 83 open, the liquid cycle through the expansion tank 50, the separation tank 54 and the tank to be cleaned 51. the pump 52 desirably has a 30 to 50 1 / o higher performance than the pump 58th

In the expansion tank 50 , the greater part of the mixture separates into an oil-containing upper layer and an aqueous intermediate layer. When the oil layer reaches the overflow 84 in the upper part of the expansion tank 50, it flows into the oil reservoir 55 . This also happens in particular when the pump 52 suddenly conveys an increased amount of mixture into the expansion tank. Gases rising in the expansion tank 50 are discharged via a vent line 86.

Liquid flows out of the expansion tank 50 through the line 70 into the separation tank 54 and is largely free of oil, deposits and gases.

The separating tank 54, like the equalizing tank 50, is provided in its upper part with heating coils in order to keep the oil in a pumpable state if necessary.

While the oil accumulating in the separating tank 54 flows through the automatic oil drain 87 to the reservoir 55 , the cleaning water freed from the oil is fed to the pump 58. The reservoir 55 can also be provided with heating coils for heating the oil. The oil reservoir and the connection line from the separation container to the pump 58 are advantageously provided with vent lines 88 and 89 .

For example, water that collects on the bottom in the reservoir 55 can be drawn off from time to time by the pump 52 and pumped back into the expansion tank 50.

If the expansion tank 50 fails, because it has to be cleaned, for example, the water that is obtained from the oil reservoir 55 and / or the separation tank 54 and / or the overflow 84 of the expansion tank 50 can be fed back through the separation tank 54 by means of the pump 52, from which the cleaning water, which has been freed from the oil , can be pumped overboard when it is not needed. Likewise, after the cleaning process has ended, the cleaning water that is no longer required can be discharged from the separating container 54 through the line 64 overboard.

If the oil reservoir 55 is full, then, as described, water can be drawn off from its lower part and conveyed back into the expansion tank 50 by the pump 52. If, however, the expansion tank 50 is already full, the pump 58 is switched off and water and / or oil is drawn off at the bottom of the oil reservoir by a pump and pumped into the expansion tank 50. From there the liquid is passed into the separating container 54, from which the cleaning liquid freed from the oil is drained overboard. If, however, the oil reservoir 55 is filled with anhydrous oil , the cleaning process is interrupted and the oil is drawn off by means of the pump 52 and filled into a further reservoir or into barrels.

If oil is to be freed from bilge water, it is expediently pumped through the open valve 71 into the separating container 54 using a piston pump. The water freed from the oil is then pumped overboard through the discharge line 64 with the valve 63 open.

If the expansion tank 50 is to be cleaned, then by means of the pump 58 with the valve 75 open, seawater is fed to a centrifugal device 57 which is introduced into the expansion tank and with the aid of which the expansion tank is cleaned. The mixture occurring at the bottom of the equalizing tank flows through the opened valve 80 and the line 70 into the separating tank 54, is freed from the oil therein and then drained overboard via the opened valve 63 and the discharge line 64.

The separation container 54 is a cyclone separator as shown in FIG . 4 is shown. It has an outer pre-separation chamber 90 and an inner separation chamber 91 . Both chambers are equipped with heating coils 92 and 93 , into which steam is introduced at 94 and 95 and exits at 96 and 97.

The mixture withdrawn from the expansion tank is introduced via the inlet connection 98 and freed of deposits in the pre-separation chamber 90 , with simultaneous heating by the heating coils 92. At 99 , a ventilation pipe is connected. From the pre-separation chamber 90 , the heated mixture, which has been freed from deposits, flows into the inner separation chamber 91, in which plates 107 are arranged. Drops of oil collect on the underside of these plates and finally rise up from the outer edge of the plates. From there, the oil is removed through an outlet opening 100.

The separation container is advantageously controlled automatically. For this purpose, a socket is provided at 101 m , which enables the connection of an electronic control. The oil can also be drawn off by hand. Test taps 102 and 103 make it possible to determine the depth of the oil layer.

The cleaning liquid freed from the oil leaves the inner separation chamber 91 through an outlet opening 104 and flows to the pump 58 as shown in FIG. 3 to.

A thermal insulation 105 protects against heat losses, and a drain opening 106 enables the separation container to be completely emptied.

Claims (1)

1. A method oily for removing trays approximations of the inner surfaces of the container walls by washing the walls with a cleaning liquid, wherein the mixture of cleaning fluid and oily deposits withdrawn from the container and in a separation container is separated again, d a d u rch g e - It indicates that the mixture, before it enters the separating container (8, 9), is passed through an equalizing container (1) which converts a fluctuating flow velocity into an essentially constant velocity, in which the greater part is of the mixture separates into an oily upper layer (46) and an oily aqueous intermediate layer (47), coarser deposits settling as bottom sludge, while the finer separation of the oily aqueous mixture into oil and cleaning liquid takes place in the separating tank (Fig . 1). 2. The method according to claim 1, characterized in that the cleaning liquid, which is separated from the mixture of cleaning liquid and removed oily deposits, is returned for the purpose of further tank cleaning. 3. The method according to claim 1 or 2, characterized in that the cleaning liquid contains water in which one or more freely soluble electrolytes are contained in order to adjust the specific gravity of the aqueous phase in accordance with the required separation. 4. The method according to claim 3, characterized in that the cleaning liquid contains sea water. 5. The method according to any one of the preceding claims, characterized in that the separation or stratification takes place in the presence of a surface-active agent. 6. Device for performing the method according to one-cm or more of the preceding claims, characterized by means (26, 29) for supplying a cleaning liquid to the location (3) of the. cleaning surfaces, means (25) for hurling the cleaning liquid against the surfaces, an expansion tank (1) for receiving the mixture of cleaning, liquid and removed oily deposits that arise during the cleaning process, a separation container (8, 9), which is connected to your Expansion tank is connected and means (27) for the return of the cleaning liquid to the location of the surfaces to be cleaned for the purpose of repeated hurling against these surfaces, the relative volumes of the expansion tank and the separation tank being such that the flow rate of the mixture of cleaning liquid and removed oily deposits in the separation tank can be kept essentially constant, regardless of the flow rate of the mixture, in the expansion tank. 7. Device * according to claim 6, characterized in that the separating container consists of a cyclone separator. 8. Device according to claim 7, characterized in that the cyclone separator has two units, namely a separation unit (9) and a heating unit (8). 9. Device according to spoke 6, 7 and 8, characterized in that means (53) for removing coarse solids in the flow line between the tank (51) which is being washed and the expansion tank (50) are provided (F i g- 3). 10. Device according to claims 6 to 9, characterized in that means (16 to 20) for withdrawing oil which is separated in the separating container (8, 9) and for introducing this oil into the expansion tank (1) are provided , which also serves as a reservoir for the recovered oil (Fig. 1). 11. Device according to claims 6 to 9, characterized in that means (84, 85) are provided to draw off oil that separates in the upper part of the expansion tank (50) and to guide it into an oil reservoir (55), into which the separated oil from the separation container (54) is also passed (FIG . 3). 12. Device according to claims 6 to 11, characterized in that it is installed on a ship. 1.3. Device according to Claim 12, characterized in that the expansion tank is formed by a cargo tank or a cofferdam. Documents considered: Belgian Patent No. 564 959; British Patent No. 350 850.