JPS5822069B2 - Method for fluidizing petroleum sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for fluidizing petroleum-based sludge.

More specifically, the present invention relates to a fluidization method for dissolving and dispersing sludge deposited at the bottom of a petroleum crude oil tank or heavy oil tank in a solvent for discharge and recovery.

When petroleum-based crude oil or heavy oil is stored in a tank for a certain period of time, fine powders, wax, etc. mixed in the crude oil or heavy oil are deposited, and petroleum-based sludge is formed at the bottom.

This sludge sticks to the bottom of the tank and must be drained away, since it reduces the effective volume of the tank and reduces the effective use of resources.

However, discharging and removing such sludge is difficult and complicated.

Various methods can be considered to discharge and remove sludge outside the tank, but the method of dissolving and dispersing heavy oil in a solvent to fluidize it and discharge it is the most effective method for reusing recovered oil and effectively removing sludge. This is generally considered to be the preferred method from the point of view of utilization.

At that time, in a generally known method, a solvent necessary to fluidize the sludge is present on the top of the sludge,
Dissolution and dispersion are promoted by adding means such as heating, stirring, and addition of chemicals.

However, such methods are extremely unsatisfactory as it takes a long time to dissolve and disperse the sludge.

The present invention was made in order to eliminate the various drawbacks of the conventional methods as described above, and when petroleum-based sludge is fluidized and discharged using a petroleum-based solvent, the sludge is treated with a small amount of surfactant. .Dissolving and dispersing the petroleum-based sludge by adding an aromatic solvent equivalent to 1% by weight or more and less than half the proportion of the petroleum-based solvent to the petroleum-based solvent and bringing the mixture into contact with the sludge. This is a method for fluidizing petroleum-based sludge.

Petroleum-based sludge in the present invention refers to sludge that solidifies and settles at the bottom of tanks, tankers, etc. when storing or transporting heavy oil such as petroleum-based crude oil or heavy oil.
Rust, water, polymeric substances, wax, oil, etc. are combined and solidified.

Petroleum solvents used in the method of the present invention include, in addition to crude oil, light oil fractions and heavy oil fractions obtained by distilling crude oil.

The amount used must be such that the recovered oil maintains sufficient fluidity when the sludge is sufficiently dissolved and dispersed, but it is usually 0.5% of the sludge.
It is about 20 to 20 times, preferably about 2 to 10 times.

The aromatic solvent has a boiling point of 150 to 3 at normal pressure.
It is a mixture whose product is an aromatic hydrocarbon having a specific gravity of 0.95 or more at 50°C and 25°C.

Examples include xylene bottom oil obtained from coke gas light oil, naphthalene oil obtained by distilling coal tar, methylnaphthalene oil, absorption oil, anthracene oil, creosote oil, or mixtures thereof.

The amount added is 0.1% by weight or more based on the petroleum sludge to be treated, and the amount thereof is less than half of the amount of the petroleum solvent.

In the method of the present invention, the reason why the amount of aromatic solvent added is limited to the above range is as follows.

That is, when the amount added is less than 0.1% by weight based on the petroleum sludge, the effect of addition is small and there is no substantial advantage.

On the other hand, when the amount added is 0.1% by weight or more based on the sludge, the effect of promoting dissolution and dispersion of the sludge by adding it in combination with a surfactant appears.

However, when the amount of aromatic solvent added increases to more than half of the amount of petroleum solvent, another problem arises.

Petroleum sludge is mostly paraffinic, and the oil recovered by dissolving it in a solvent usually has an elevated pour point.

From the sludge side, the pour point of the sludge decreases because it is dissolved and diluted with oil.

When compared under the same solvent/sludge ratio, the rate of drop in the pour point of sludge due to dissolution and dilution with a solvent is greater when aromatic solvents are used than when petroleum-based solvents are used. In addition, when aromatic solvents are used, the pour point is initially quite large (even if it falls, the pour point rises as time passes and tends to return to a value close to that of sludge alone). It was discovered.

When using a mixture of petroleum solvent and aromatic solvent as the solvent, the degree of the above phenomenon will vary depending on the mixing ratio, but if the ratio of aromatic solvent/petroleum solvent is 0.5 or less It turned out that there wasn't much of a problem.

Any oil-soluble surfactant can be used; for example, as anionic surfactants, alkylbenzene sulfonic acids and their salts, alkyl sulfates and their salts, polyoxyalkylene Alkyl ether sulfates and their salts, polyoxyalkylene fatty acid ester sulfates and their salts, polyoxyalkylene alkylphenyl ether sulfates and their salts, dialkyl sulfosuccinates and their salts, α-sulfo fatty acids and their salts, α-sulfo fatty acid alkyl esters and their salts,
Examples include α-olefin sulfonic acids and salts thereof, alkanesulfonic acids and salts thereof, petroleum sulfonic acids and salts thereof, alkyl phosphates and salts thereof, polyoxyethylene alkyl ether phosphates and salts thereof, fatty acid soaps, and the like.

In addition, as nonionic surfactants, polyoxyalkylene alkyl ether, polyoxyalkylene alkylphenyl ether, polyoxyalkylene fatty acid estenoben rubitan fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, fatty acid monoglyceride,
Polyoxyalkylenealkylamine, pluronic type poly(oxyethylene)-poly(oxypropylene)
Cocondensate, tetronic poly(oxyethylene)
Examples include poly(oxypropylene) cocondensates.

As the cationic surfactant, quaternary ammonium salts such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkyldimethylbenzylammonium salts are mainly used.

As the amphoteric surfactant, N-alkylglycine, dimethylalkylbetaine, etc. are used.

Cationic surfactants and amphoteric surfactants are generally expensive, and the composition recovered by the method of the present invention
For example, considering that the surfactant is used as a fuel, it is preferable to use a relatively inexpensive anionic surfactant or nonionic surfactant in the present invention.

Incidentally, the surfactants that can be used in the present invention are not limited to those exemplified.

Therefore, the amount of these surfactants added is 0.01 to 1% by weight, preferably 0.05% by weight based on the petroleum sludge.
~0.5% by weight.

To carry out the method of the present invention, a predetermined amount of petroleum solvent is supplied as a solvent to a tank containing petroleum sludge, and further, predetermined amounts of an aromatic solvent and a surfactant are added and stirred to form a sludge. dissolves and disperses.

At this time, if the temperature is heated to 40 to 80°C, the dissolution and dispersion effect will be further enhanced.

Next, the method of the present invention will be explained in more detail with reference to Examples.

Example A dissolution and dispersion test was conducted using bottom sludge from a crude oil tank having the physical properties shown in Table 1.

Prepare 3 beakers with a capacity of 11, and put 200 ml of sludge at the bottom of each beaker. and 800 ml of A heavy oil were charged.

' Ai: A surfactant and an aromatic solvent were added to the beaker 1, only a surfactant was added to the beaker /I62, and nothing was added to the beaker A3.

The types and amounts of the drugs used are shown in Table 2.

Place each beaker in a jar tester with a constant temperature bath.
The center of the liquid was stirred at 70° C. at a speed of 50 r, p, m.

We sampled a small amount of the upper layer liquid during stirring and measured the n-hebutane insoluble content at 20°C to measure the change over time in the dissolution and dispersion rate of sludge in the solvent.
The results shown in the figure were obtained.

In addition, in FIG. 1, curve A is A61, curve B is A2,
Curve C is test data in a /V;3 beaker.

Reference example: Minas crude oil tank bottom sludge (pour point 60°C), petroleum A heavy oil (pour point -10°C), and coal tar hydrocarbon mixed oil (boiling point 150-250°C, pour point -7)
When the pour point curve was measured for a mixed solution using a solvent at 5° C., the results shown in FIG. 2 were obtained.

In addition, in the same figure, curves are when only coal tar solvent is added as a solvent, curve E is when coal tar solvent and heavy oil A are added at a ratio of 2:1, and curve F is when coal tar solvent and heavy oil A are added. Curve G shows the relationship between the sludge ratio and the pour point when heavy oil and heavy oil are added at a ratio of 1:2, and curve G shows the relationship between the sludge ratio and pour point when only heavy oil A is added.

In addition, a mixed solution of sludge and solvent (weight ratio 1:2) was added to 6
The pour point change curve when the sample was left standing at 0° C. was as shown in FIG.

In the same figure, curve H is when only coal tar solvent is added as a solvent, curve ■ is when coal tar solvent and heavy oil A are added at a ratio of 2:1, and curve J is when coal tar solvent and heavy oil A are added. The relationship between the number of elapsed days and the pour point is shown when heavy oil is added at a ratio of 1:2, and the curve shows the relationship between the number of elapsed days and the pour point when only A heavy oil is added.

In addition, in the above, the mixing ratio of the coal tar-based solvent and the petroleum-based solvent as solvents is a weight ratio.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between sludge dispersion rate and elapsed days in the method of the present invention and the conventional method, and FIG. 2 is a graph showing the relationship between sludge ratio and pour point when various solvents are mixed. FIG. 3 is a graph showing the relationship between the number of days elapsed and the pour point when various solvents are mixed.

Claims (1)

[Scope of Claims] 1. When petroleum-based sludge is fluidized and discharged using a petroleum-based solvent, an amount such that, together with a small amount of surfactant, the amount is 0.1% by weight or more based on the sludge and the proportion relative to the petroleum-based solvent is half. A method for fluidizing petroleum-based sludge, characterized in that the petroleum-based sludge is dissolved and dispersed by adding an aromatic solvent corresponding to the following to the petroleum-based solvent and bringing the mixture into contact with the sludge. 2 The aromatic solvent has a boiling point of 150 to 350 at normal pressure.
Claim 1, which is a mixture whose main component is an aromatic hydrocarbon having a specific gravity of 095 or more at 25°C.
The method described in section. 3 The amount of surfactant used is 0.01 to 0.01 to sludge.
A method according to claim 1 or 2, wherein the amount is 1% by weight. 4. The method according to claim 3, wherein the surfactant is oil-soluble. 5 The amount of petroleum solvent used is 0.5 to 2 for sludge.
The method according to any one of claims 1 to 4, wherein the amount is 0 times. 6. The method according to claim 5, wherein the petroleum solvent is crude oil, a light oil fraction obtained by distilling crude oil, or a heavy oil fraction. 7. The method according to any one of claims 1 to 6, wherein the dissolution and dispersion treatment is carried out at a temperature of 40 to 80°C.