JPS5958085A - Treatment of washing oil of tar acid extraction liquid - Google Patents

Abstract

PURPOSE:To recover tar acid and light tar oil, in high efficiency, by washing tar acid extraction liquid with a light tar oil, introducing the recovered oil used for the washing of tar acid extraction liquid (hereinafter referred to as extract washing oil) into the tar distillation step, and distilling the extract washing oil together with tar. CONSTITUTION:Tar acid extraction liquid obtained by extracting a hydrocarbon oil mixture containing tar acid with an aqueous solution of caustic alkali, is introduced through the line 1 into the light-component washing column 2 and made to contact countercurrently with the light tar oil (preferably the crude light oil recovered from the refining process for coke oven gas) supplied through the line 3. The recovered extract washing oil is introduced into the tar distillation step. The extract washing oil is preferably introduced into and mixed with the reflux liquid of the dehydration solumn through the line 21, and the control of the distillation process is preferably carried out by controlling the column bottom temperature of the dehydration column 10. EFFECT:The aolumn top temperature is decreased by increasing the amount of the reflux of the dehydration solumn, and the quality of the distilled light tar oil is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method (1) for producing tar acids from a hydrocarbon oil mixture containing tar acids such as phenol obtained in a tar distillation process. The present invention relates to a method for processing an extract washing oil obtained by extracting with t(1) and washing the obtained tar acid extract with tar-based light oil.

Hydrocarbon oil mixtures obtained in the tar distillation process, especially naphthalene oil and carpol oil, contain large amounts of tar acids such as phenol. After preparing 1 g of alkali tar acid, the product is made into a product by subjecting it to double decomposition treatment with carbon dioxide gas or the like.

By the way, tar acid extracts such as tar acid alkaline salts obtained by extracting and separating tar acids from hydrocarbon oil mixtures also contain tar base components, neutral oil components such as naphthalene oil and carpol oil, and other impurities. Therefore, if this tar acid extract is subjected to double decomposition treatment with carbon dioxide gas, etc., these impurities will migrate into the product tar acids (= these impurities will be transferred and cause quality deterioration, so these impurities should be removed). Needs to be removed.

Therefore, the tar acid extract is washed with tar-based light oil to separate and remove these impurities, but if the amount of tar-based light oil used is small, the impurities will not be completely separated and removed. If the amount used is increased, some tar acids will migrate to the tar-based light oil used for cleaning the tar acid extract, i.e., the tar acid extract cleaning oil (D), and this tar acid extract cleaning oil will be transferred to the tar acid extract cleaning oil in the light oil distillation process. When processed, the quality of the J gas oil obtained may deteriorate.

In view of this point of view, the present inventors have attempted to obtain highly pure IW tar acids by sufficiently washing the tar acid extract with tar-based light oil (2. The tar acid extract recovered at this time) As a result of intensive research into methods for effectively processing cleaning oil, we have found that by charging tar acid extract cleaning oil into the tar distillation process, tar bases, naphthalene oil, and tar acids in tar acid extract cleaning oil can be removed. was separated and recovered again, and it was discovered that tar acids could be recovered with high purity and efficiency, and tar-based light oil, which is a cleaning oil, could also be recovered with high purity and efficiency, and the present invention was achieved. It is something.

That is, the present invention involves extracting a hydrocarbon oil mixture containing tar acids such as phenol obtained in a tar distillation process with an aqueous caustic alkali solution, and washing the obtained tar acid extract with a tar-based light oil. In the method for treating an acid extract, the above-mentioned tar acid extract is washed with an extract-washing oil that is charged into a tar distillation step.

In the present invention (2), the hydrocarbon oil mixture containing tar acidity 1 such as phenol obtained in the tar distillation process is a tar oil containing a fraction of about 150 to 300 °C, preferably about Naphthalene oil with a boiling point of about 200-250°C or oil with a boiling point of about 170-200°C
Lubol oil or tar oil from which specific components such as naphthalene have been removed can be mentioned. Carpol oil also contains phenol,
It mainly contains o-cresol, m-cresol and p-cresol.

In addition, in order to extract tar acids from these hydrocarbon oil mixtures (1. The caustic alkali aqueous solution used is typically a caustic soda aqueous solution, and the hydrocarbon oil mixture is extracted with this caustic alkali aqueous solution. (From the second point, tar acids in the hydrocarbon oil mixture become water-soluble tar acid alnochloride salts and migrate into the caustic alkali aqueous solution.

The aqueous caustic alkali solution obtained in this manner, that is, the tar acid extract, contains the main components such as water-soluble tar bases, naphthalene oil, and carpol oil contained in the hydrocarbon oil mixture. A small amount of oil is present as an impurity. If this tar acid extract is directly metathesized to produce tar acids, the concentration of impurities in the obtained tar acids will increase, and the quality of the tar acids as a product will deteriorate. Therefore, this tar acid extract is washed with nital-based light oil before its double decomposition treatment.

The tar-based light oil used for this purpose is a light oil consisting of benzene, toluene, xylene, etc. or a light oil containing these, and is usually a tar light oil obtained in a tar distillation process or a crude light oil obtained in a coke oven gas refining system. etc. can be used. The concentration of tar bases contained in tar light oil is usually about 10 to 1.5 mg/A, while the concentration of tar bases contained in crude light oil from coke oven gas refining systems is generally about 0.3 mg/A. ~0.7 mg/A, which is much less than the former.

Therefore, the tar salts contained in the tar acid extract
(Coke oven gas refining crude light oil has an excellent ability to wash and extract components.

By the way, among the impurities in the tar acid extract, neutral oil and low Hu point tar base can be easily separated and removed by washing with tar-based light oil, but high boiling point tar base cannot be easily separated. cannot be removed,
In order to obtain high-purity tar acids, it is necessary to use a large amount of tar-based light oil. Therefore, in the present invention, tar-based light oil is usually added to 100 parts by weight of tar acid extract. 6 to 30 parts by weight, preferably 10 to 20 parts by weight
Weight: g13 is used. If the amount of tar-based light oil used is less than 6@Hayabe, the debasing rate will decrease and it will be difficult to produce high-purity product tar acids, and even if the amount used exceeds 30 parts by weight, it will not be recovered. The effect remains the same, just by increasing the amount of tar acid extract and cleaning oil used.

The washed tar acid extract is subjected to double decomposition treatment with an acidic substance such as acid or carbon dioxide, thereby obtaining liberated tar acids. Distillation treatment, etc. (secondary, phenol, 0
-Creol, m-cresol, p-cresol, quinlenol, etc. (1 separation.

The tar acid extract cleaning oil recovered by washing the tar acid extract with tar-based light oil is charged into a tar distillation process (two charges, and the extract cleaning oil is treated with tar (two treatments).''1. The tar acid extract cleaning oil contains tar acid in addition to the tar base and neutral oil components, and this tar acid extraction results in the tar acid content migrating into the cleaning oil. increases approximately in proportion to the amount of cool light oil used for cleaning the tar acid extract, that is, the amount of cleaning oil used.

Therefore, if this tar acid extract wash oil is directly charged into a gas oil distillation process, the tar acid concentration in the resulting gas oil, especially heavy gas oil, will increase approximately in proportion to the increase in tar acid content, resulting in deterioration of quality. In the present invention, since the tar acid extract cleaning oil is charged into the tar distillation process and treated together with the tar,
The tar distribution is transferred again to a hydrocarbon oil mixture containing tar acids such as naphthalene oil and carpol oil and recovered, and the purity of the 11 yen oil and products such as benzene, toluene, and xylene that are distilled from it are also determined. Purity is the best
d.

Since the tar acid extract washing oil contains water transferred from the tar acid extraction liquid, it is preferably charged into the dehydration tower (:) of the tar distillation process.Charging to the dehydration tower is carried out via the raw material line. Alternatively, the tar acid extract washing oil may be directly charged into the column, although it is not particularly limited. Preferably, the tar acid extract washing oil is mixed with the dehydration tower reflux liquid and the dehydration tower is charged as the reflux liquid. In this case, if the distillation control method is to keep the top temperature constant, the amount of heating from the bottom of the column will increase and the energy loss will be significant. Energy loss can be minimized by a method that constantly controls the bottom temperature of the dehydration tower.Therefore, in order to carry out the method of the present invention, the bottom temperature of the dehydration tower must be kept constant as the reflux liquid. It is preferable to control the temperature at a constant level, which is the same as when no charging is carried out.In addition, as a result of mixing the tar acid extract washing oil with the dehydration tower reflux liquid, the reflux α increases by that amount. It was found that the separation of heavy oil was promoted and the quality of tar light oil obtained from this dehydration tower was significantly improved.Especially, when the reflux liquid was increased to about twice that of the conventional one, the distillation process was improved. Since the quality is the same as that of light gas oil when it is redistilled and separated into light gas oil and heavy gas oil, the load on the gas oil distillation process can be reduced.

The method of the present invention (the waviness is approximately 4% in the tar acid extract cleaning oil)
The tar acids that were previously contained in the tar gas oil distilled from the dehydration tower have been reduced to about 0.4 times the tar gas oil distilled from the dehydration tower, and the tar acids removed in the dehydration tower are entrained in the dehydrated coal tar and are then distilled into tar distillation. The recovery rate of this tar acid is improved and the reflux amount of the dehydration tower is increased, which lowers the temperature at the top of the tower and changes the composition of the tar gas oil distilled from Furthermore, the tar gas oil distilled from this dehydration tower is mixed with crude gas oil and processed in the gas oil distillation process (in a distillation column that separates the soft and coarse components in the second step). , from this distillation column
The concentration of tar acid in the heavy gas oil produced was stabilized at about 5 to 6% R% or less, and the distillation column and boiler became less fouled, resulting in favorable conditions.

” Hereinafter, the method of the present invention will be explained based on a flow route according to an example of implementation of the present invention.

In the figure, tube 1sD) is the charging line for tar acid extract.
The tar acid extracted oil charged into the light washing tower (2) from this charging line (1) is washed in countercurrent contact with the tar-based light oil charged from the line (8), and purified. The resulting tar acid extract is taken out from line (4.).

On the other hand, the coal tar transferred from the line (5) is transferred to the transfer pump (6), preheater (7) and heat exchanger (8).
The dehydrated coal tar is then charged into a dehydration tower 00) through line (9), and dehydrated coal tar is extracted from the lower part of this dehydration tower 00) through line 0υ, and this dehydrated coal tar is charged into a distillation column and subjected to distillation treatment. Ru.

A tar gas oil reflux line OΦ equipped with a pump (13) is provided, and the mixture of tar gas oil and water extracted from the upper part of the dehydration tower Qo is separated from oil and water by a separator (13), and the water is passed through the line ( 19 are to be extracted.

The tar gas oil separated into oil and water by the separator (Ia) is
A part of it is used as a reflux liquid in the reflux line (1.υ) installed at the top of the dehydration tower (1o).
'1ll (divided into line (10), through this line 0 → tar light oil tank 07) (2) is charged. In addition, this cool light oil tank 0η (2 is branched from line (3) Line #4 (from the second line, tar-based light oil that was not used for cleaning the tar acid extract is charged.

The tar gas oil discharged from the small tar tank (17) is charged into the distillation column 0, and is converted into light gas oil (17).
9) and heavy gas oil 120).

Incidentally, the tar acid extract washing oil made of tar-based light oil used for washing the tar acid extract in the light washing tower (2) is extracted from the light washing tower (2) and transferred to the transfer line (
The reflux pump (13) of the dehydration tower 00 is inserted into the dehydration tower (10) through the 2η, and the tar light oil that refluxes through this reflux line (11) is charged into the dehydration tower (10).

Furthermore, the line shown by the one-dot chain line (2■ is the dehydration tower (10
An example is shown in which the quality of tar gas oil extracted from the line (1+9) is improved by increasing the reflux ratio of As a result, the tar gas oil flowing through the line (+43) is combined with the light gas oil (09) in the distillation column of the gas oil factory (the quality is almost the same as the light gas oil (19) obtained from the old method, and is passed through the line (a) to the distillation column). It is possible to reduce the burden of zero phrases.

Hereinafter, the method of the present invention will be specifically explained based on Examples.

Table 1 shows a comparison with operating conditions when 100 parts by weight/hr of tar acid extract was not used for cleaning.

In addition, the changes in the properties of the tar light oil obtained at this time were
Shown in the table. Furthermore, we determined the debasing rate and the oil filling rate in the membrane of the purified tar acid extract extracted from line (4), and also determined the The tar acid concentration was also measured.The results are summarized in the third table along with the results of a comparative example in which tar acid extract cleaning oil was charged into a tar light oil tank θη and distilled using a distillation column θ.
Table (2 shown)

Table 1 Table 3

[Brief explanation of the drawing]

The figure shows flown-1 showing an example of the method of the present invention. 59

Claims (1)

[Scope of Claims] (11) Tar acid obtained by extracting the hydrocarbon oil mixture containing tar acids obtained in the tar distillation process with an aqueous caustic alkali solution and washing the obtained tar acid extract with tar-based light oil. A method for processing a tar acid extract washing oil, characterized in that the extract washing oil recovered by washing the tar acid extract described in 1. is charged into a tar distillation step. (2) The method for treating tar acid extract cleaning oil according to claim 1, wherein the tar acid extract cleaning oil is charged into a dehydration tower in the tar distillation step. (3) The tar acid extract cleaning oil is charged into a dehydration tower in the tar distillation step. A method for treating tar acid extract washing oil according to claim 2, which comprises mixing the oil with a reflux liquid and charging the oil to a dehydration tower as a reflux liquid. A method for treating tar acid extract cleaning oil according to claim 2 or 3, in which the temperature is controlled at a constant temperature. A method for treating tar acid extract cleaning oil according to any one of claims 1 to 4. (6) Claim ?A'51 in which the hydrocarbon oil mixture is naphthalene oil and/or carpol oil. Section to 5th
A method for treating tar acid extract cleaning oil according to any one of paragraphs.