JPS6129997B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is characterized in that in a crude oil tank or the like, residual oil remaining at the bottom and containing a large amount of wax components is treated together with the crude oil, discharged outside the tank, and recovered. The present invention relates to a method for recovering residual crude oil in a tank.

As is well known, residual oil (sludge) accumulates at the bottom of crude oil tanks after long-term use. This residual oil contains a large amount of wax and solidifies, which not only interferes with the operation of the tank and associated equipment, but also causes a decrease in the internal volume of the tank, so it must be removed periodically.

The conventional method for removing residual oil is to drain most of the crude oil from inside the tank, then insert a hose so that it reaches the bottom of the tank, and forcefully spray oil, water, steam, etc. from the hose to remove the remaining oil from the bottom. It is peeled off and discharged from the tank in a mixed state of oil and water. In addition, water or seawater is supplied after most of the crude oil has been discharged from inside the tank, and steam is supplied to the existing heating coil to heat the water to 80℃, causing the heated and dissolved residual oil to float to the surface of the water. A method of pumping out is also adopted. Furthermore, various methods other than those described above are known.

However, both methods require considerable time and effort in large-scale crude oil tanks, and the residual oil that is discharged contains large amounts of water and chemical agents, so it cannot be purified by oil-water separation and is discarded. Must.

In the present invention, while fluid crude oil is present in the residual oil layer deposited at the bottom of the crude oil tank, heated water is injected in a substantially horizontal direction above the crude oil to warm the crude oil, and the heated crude oil and hot water are heated. The residual oil is made into a fluid state by the injection force of the heated water, and is moved to the periphery of the crude oil tank by the injection force of the heated water, and the remaining oil is discharged as a mixture of crude oil and hot water by pumping out, and the oil and water are separated. The residual oil can be used again since it is recovered and a wax dispersant is added to the recovered residual oil or mixed and diluted with diluted oil. Therefore, not only is there no economic waste, the installation is extremely simple and the processing time can be shortened.

Next, the recovery method of the present invention will be explained based on the drawings. The solidified residual oil a containing a large amount of wax inside the floating roof type crude oil tank 1 is generally deposited and solidified at the bottom, so the residual oil recovery process Sometimes a small amount of fluid crude oil b is present in the residual oil. The amount of crude oil is suitable, but it must be sufficient to dissolve at least all the residual oil when heated.

A hot water injection device 3 is provided on the flange of a manhole 2 on the inner side wall of the crude oil tank 1.
Connect the connecting pipe 4 to. A heating device 5 is installed in the connecting pipe 4.
is provided and connected to the three-way valve 6, and the three-way valve 6 is connected to a water supply pipe 7 and a reflux pipe 8. The reflux pipe 8 is connected at the other end to an oil-water separator 10 which is connected to a discharge pump 9 from the bottom of the crude oil tank 1 . A supply pipe 11 for supplying an oil-water separation agent is connected to the heating device 5.

The injection device 3 described above can inject hot water into the crude oil tank 1 in a substantially horizontal direction above the crude oil,
It also has a structure that allows it to swing back and forth from side to side while remaining in a substantially horizontal position to spray hot water into a fan-shaped area. This injection device 3
The reciprocating swing may be made automatically by the force of hot water jets, or may be made to swing while being mechanically or manually operated from outside the crude oil tank.

Such an injection device 3 is installed at several locations (3 to 4 locations) on the side wall of the crude oil tank, and when the residual oil is being discharged, the manhole 2 cover is opened and the injection device 3 is attached to the flange to supply water. Just connect the pipe 7.

In order to recover the residual oil inside the crude oil tank 1 formed in this manner, water supplied from the water supply pipe 7 is heated to 60 to The mixture is heated to 90° C., an oil-water separation agent is added as required, and the mixture is supplied to the injection device 3 through the connecting pipe 4. Therefore, when hot water is injected above the crude oil simultaneously or alternately, continuously or intermittently from a plurality of injection devices, the hot water is supplied to the entire bottom of the crude oil tank 1, forming a shower shape and increasing the fluidity. It is supplied to the top of a certain crude oil layer and warms the crude oil layer. Then, due to the heat of the heated crude oil layer and the injection force of hot water, the residual oil layer with a lot of wax components in the lower layer is dissolved.
Provides liquidity. When the residual oil layer becomes fluid, the hot water supplied to the top reaches the residual oil layer, and in the process, the residual oil layer is further heated, promoting dissolution, and the crude oil and residual oil mix and flow onto the water layer. surface.

As mentioned above, the residual oil dissolves or partially dissolves and separates from the bottom of the crude oil tank 1, and when it becomes fluid, it remains in the center of the bottom of the crude oil tank by the hot water injection force of the injection device that is injected from the side. without being forced to move to the vicinity of the crude oil tank. The residual oil that has moved to the surrounding area is pumped out by a pump 9 together with crude oil and hot water, and is guided in a heated state to an oil-water separator 10 such as API or CPI. The hot water separated by this device 10 is passed through the three-way valve 6 from the reflux pipe 8, heated to a predetermined temperature by the heating device 5, and then refluxed to the crude oil tank 1 from the connecting pipe 4.

The oil component containing the residual oil component separated in the oil-water separator 10 is further removed with a centrifuge or the like, or without water, and mixed with other fluid oils as diluent oil in the mixer 12. Further, when a diluent oil is mixed with the above-mentioned oil component, the wax component may re-precipitate, so a dispersant may be added to prevent the wax component from re-precipitating.

As is clear from the above, according to the present invention, while residual oil and fluid crude oil are present at the bottom of a crude oil tank, heated water is injected in a substantially horizontal direction above the crude oil to heat the crude oil. The residual oil is made into a fluid state by the heated crude oil and the injection force of hot water, and the residual oil is moved to the periphery of the crude oil tank and discharged by the injection force of the heated water, so the residual oil is removed extremely efficiently. Becomes a fluid state. In addition, since hot water is injected from above the crude oil in a substantially horizontal direction, the dissolved residual oil and crude oil immediately move to the periphery of the crude oil tank together with the hot water.
The time and effort required to recover residual oil can be significantly reduced. Therefore, since it is only necessary to install a hot water injection device in a manhole, for example, when recovering residual oil in a crude oil tank, it can be carried out even in an existing crude oil tank, and is particularly effective in a large crude oil tank.

[Brief explanation of the drawing]

The drawings are schematic illustrations of embodiments of the invention.

Claims (1)

[Claims] 1 With residual oil and fluid crude oil present at the bottom of the crude oil tank, hot water is injected approximately horizontally above the crude oil using an injection device to supply it to the upper surface of the crude oil. The residual oil is made into a fluid state by the heated crude oil and the hot water injection force, and the fluidized residual oil is moved to the periphery of the crude oil tank by the hot water injection force of the injection device, and the oil and water are mixed in the crude oil tank. A method for recovering residual oil at the bottom of a crude oil tank, characterized by discharging it to the outside.