JPH0372565B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous alkaline hydrosulfide solution (hereinafter referred to as "alkaline hydrosulfide liquid") produced in a petroleum-related factory.
The present invention relates to a method for treating or recovering an alkali hydrosulfide solution, which removes dissolved acidic oil from the production reaction system and prevents the solvent from being mixed with the alkali hydrosulfide solution.

Alkali-soluble acidic oil coexists in cracked gas, fuel gas, waste gas, naphtha, kerosene, etc. in petroleum-related factories, and alkaline liquid cleaning for the purpose of desulfurization, deoxidation, refining, etc. dissolve in Therefore, since such alkaline cleaning waste liquid contains a large amount of acidic oil dissolved therein, it is difficult not only to utilize it, but also to treat pollution, and it is generally treated by neutralization. However, this method not only requires a large amount of chemical solution for neutralization, but also generates acidic gases such as H ₂ S during the neutralization process, and also generates bad odors caused by mercaptans, making it difficult to treat these pollutions. Secondary and tertiary treatment is now essential, and those involved are struggling because the treatment process is complex and requires a large amount of expense.

Under these circumstances, it is clear to all concerned that the numerous technologies developed by the present inventors for producing alkaline hydrosulfide liquid from alkaline waste liquid, H ₂ S-containing gas, etc. have been put into practical use and are proving effective. (Patent No. 401527, Patent No. 404799, Patent No. 417114, Patent No. 418472, Patent No. 800401, Patent No.
900772).

However, the alkaline hydrosulfide solution produced by these methods contains a small amount of dissolved acidic oil (solubility limit) that is separated and removed in the production process. In this way, the composition of the trace amount of acidic oil dissolved in the alkali hydrosulfide solution varies depending on the alkaline waste liquid that produces the alkali hydrosulfide solution and the _H2S -containing gas, but phenols, thiophenols, mercaptans, etc. It contains one or more species and is a cause of bad odor.

Therefore, the present inventors have developed a method for dealing with the bad odor of alkaline hydrosulfide liquid that has trace amounts of acidic oil dissolved in it, using activated carbon for petroleum fractions such as kerosene, their refined fractions, or these fractions. We have developed and put into practical use a method to remove malodorous acidic oils through extraction treatment using coexisting oils (patent no.
638775). However, although mercaptans can be easily removed using this method, acidic oils such as phenols and thiophenols, which have relatively high solubility in water or are highly acidic, may still remain in the alkaline hydrosulfide solution. There is. Such an alkaline hydrosulfide solution still has a slight odor due to acidic oil. If this method were to be used to almost completely remove phenols and thiophenols from the alkali hydrosulfide solution, it would be necessary to remove extremely large amounts of extracted fractions such as petroleum fractions and their refined fractions (the number of alkali hydrosulfide solutions). 10 times or more), and when these fractions and activated carbon are used together for treatment, the effect of removing acidic oils is improved, but the activated carbon adsorbs a large amount of these fractions, making the regeneration process complicated and difficult to regenerate. There are concerns that this will increase costs.

When concentrating and producing a product (alkaline hydrosulfide content approximately 70 wt%) containing such a small amount of dissolved acidic oil, the acidic oil is transferred to the evaporation drain during the concentration process, and dissolved H ₂ S Even excluding
Since the drain has a high COD, it is necessary to treat the drain with pollution prevention treatment using NaClO, oxygen, etc. Furthermore, there is concern that this pollution prevention treatment not only requires a large amount of chemicals, but also significantly complicates the treatment and operation process. .

Under these circumstances, the present inventors added ketone-based, alcohol-based, ether-based, and ester-based solvents that are sparingly soluble or insoluble in water to the hydrosulfide alkali solution or the production reaction system of the hydrosulfide alkali solution produced in petroleum-related factories. One or more solvents (hereinafter referred to as extraction solvent), or a mixed solvent of these solvents and a solvent that is even more insoluble in water (hereinafter referred to as insoluble solvent) are added and dispersed in the processing liquid. A method for treating or recovering an alkali hydrosulfide solution, which is characterized by extracting and removing a trace amount of acidic oil dissolved in the alkali hydrosulfide solution (JP-A-Sho)
60-84194)).

Although the acidic oil content and the bad odor caused by the acidic oil have been removed from the alkaline hydrosulfide solution obtained by this method, especially when treated with only an extraction solvent, the odor of the solvent used remains and the alkaline hydrosulfide solution is A phenomenon was observed in which a small amount of COD remained in the condensate generated during concentration, even though there was almost no acidic oil content. However, the alkaline hydrosulfide solution obtained by treatment with a mixed solvent of an extraction solvent and an insoluble solvent has no odor due to acidic oil, no residual odor from the solvent used, and no COD in the drain generated due to concentration. There was no residue left.

Therefore, the present inventors conducted further research and found that a two-step treatment method in which the extraction solvent was first used and then the insoluble solvent was used to remove the acidic oil from the alkali hydrosulfide solution and to remove the extraction solvent. The present invention was achieved by discovering that odor can be removed and COD in the evaporation drain when concentrating an alkali hydrosulfide solution can be further reduced.

That is, the present invention applies a ketone-based, alcohol-based, ether-based, or ester-based solvent that is sparingly soluble or insoluble in water to a hydrogen sulfide alkali solution or a hydrosulfide alkali solution production reaction system that dissolves acidic oil produced in a petroleum-related factory. A first step of adding and dispersing an extraction solvent consisting of one or more of the following to treat or recover the alkali hydrosulfide solution to remove acidic oil; and adding an insoluble solvent to the alkali hydrosulfide solution obtained in the first step. The second step of addition and dispersion removes the trace amount of extraction solvent mixed in the alkaline hydrosulfide solution, and removes the extraction solvent from the drain generated as the alkaline hydrosulfide solution concentrates.
This provides a method to significantly reduce COD.

Extraction solvents used in the present invention include ketone solvents such as isobutyl methyl ketone, butyl methyl ketone, and methyl propyl ketone, alcohol solvents such as 2-ethylhexanol, n-octanol, and n-heptanol, and ether solvents such as dibutyl ether. , isopropyl ether, etc., n-butyl acetate as an ester solvent, 1,1,1-trichloroethane as a halogenated hydrocarbon solvent, etc., which is sparingly soluble or insoluble in water, and is alkali. It is also a stable solvent, and suitable insoluble solvents include n-hexane, n-heptane, and silicone oil.

In the method of the present invention, the amount of the extraction solvent and insoluble solvent added is preferably at least 2% by volume or more relative to the amount of the processing liquid, because if the amount is too small, the contact efficiency will be poor and operations such as stirring and shaking will be required for a long time. It is something.

Furthermore, the insoluble solvent used in the second step can effectively remove the extraction solvent mixed with the alkali hydrosulfide solution even if it is repeatedly used until the content of the extraction solvent reaches about 50% by volume. The insoluble solvent can be separated and recovered by distillation and reused.

Furthermore, in the first step using an extraction solvent, the proportion of alkali sulfide in the alkaline hydrosulfide solution is high (in the alkaline hydrosulfide solution or its production reaction system).
If the alkali sulfide content is 7 mol% or less and preferably 5.5 mol% or less based on the alkali hydrosulfide content, the acidic oil content may be reduced by the alkali hydrosulfide content. It can be effectively removed at room temperature without affecting the concentration.

The extraction solvent used to extract the acidic oil can be easily regenerated with caustic alkaline solution by a conventional method and can be used repeatedly.

As explained above, in the method of the present invention, in the first step, a ketone-based, alcohol-based, ether-based, or ester-based solvent is added to the hydrosulfide alkaline solution or the hydrosulfide alkaline solution production reaction system produced in a petroleum-related factory. After the alkaline hydrosulfide solution is treated or recovered by adding and dispersing a species or an extraction solvent consisting of two or more types, in the second step, an insoluble solvent is added and dispersed to the alkali hydrosulfide solution treated or recovered in the first step. This method removes trace amounts of acidic oil dissolved in the alkaline hydrosulfide solution, prevents the extraction solvent from being mixed with the alkaline hydrosulfide solution, and removes the evaporation condensate that occurs as the alkali hydrosulfide solution concentrates. This is a treatment or recovery method for alkaline hydrosulfide that has made it possible to significantly reduce COD.

Next, in order to make the method of the present invention more clear, it will be specifically explained using examples.

Example 1 As the first step, NaSH liquid 1 with the composition and properties shown in Table 1 was produced in an oil refinery.
and 80 ml of isobutyl methyl ketone, a ketone solvent, as an extraction solvent to remove acidic oil from the NaSH solution were placed in a flask 2 equipped with a stirring device, stirred for 5 minutes, and then separated by a standing method. As a result, a treatment liquid as shown in Table 2 which contained almost no acidic oil and also had no bad odor caused by the acidic oil was obtained.

Next, in the second step, 0.8 of the treatment liquid from the first step,
Add 30 ml of n-hexane as an insoluble solvent to remove the extraction solvent odor (isobutyl methyl ketone odor) into a flask equipped with a stirring device, stir for 5 minutes, and then separate the solvent by a standing method. A treated liquid from which the odor of the extraction solvent was removed was obtained as shown in Table 3.

This treatment liquid is concentrated and the generated drainage is
The COD was significantly lower than that of the treatment solution in the first step (Table 2).

Table 1 Composition and properties of NaSH liquid NaSH 26.80wt% Na ₂ S 2.01 〃 Na ₂ CO ₃ 1.00 〃 Na ₂ SO ₃ 0.65 〃 Na ₂ S ₂ O ₃ 0.20 〃 Acidic oil content 450ppm Drain COD (Note) 1060 〃 Na ₂ S/NaSH (5.39 mol%) (Note) Dissolved H ₂ S is removed from the evaporation drain generated when NaSH solution is concentrated to 70 wt%.

Table 2 Composition and properties of treatment liquid in the first step NaSH 26.79wt% Na ₂ S 2.02 〃 Na ₂ CO ₃ 0.99 〃 Na ₂ SO ₃ 0.65 〃 Na ₂ S ₂ O ₃ 0.20 〃 Acidic oil 3ppm Drain COD 38 〃 Extraction solvent odor Yes Table 3 Composition and properties of treatment liquid NaSH 26.80wt% Na ₂ S 2.01 〃 Na ₂ CO ₃ 0.99 〃 Na ₂ SO ₃ 0.64 〃 Na ₂ S ₂ O ₃ 0.22 〃 Acidic oil 3ppm COD in drain 5 〃 Comparative example with no extraction solvent odor NaSH solution 1 with the composition and properties used in Example 1
The first step was performed in the same manner as the first step of Example 1 using a mixed solvent of 80 ml of isobutyl methyl ketone and 30 ml of n-hexane as an insoluble solvent as an extraction solvent to remove acidic oil from the NaSH solution. As a result, a treatment solution as shown in Table 4 was obtained.

Although this treated solution contained almost no acidic oil, it had an extraction solvent odor, and the COD in the drain generated by concentration was equivalent to that of the treated solution in the first step of Example 1 (Table 2). .

Table 4 Composition and properties of treatment liquid NaSH 26.78wt% Na ₂ S 2.00 〃 Na ₂ CO ₃ 1.01 〃 Na ₂ SO ₃ 0.64 〃 Na ₂ S ₂ O ₃ 0.20 〃 Acidic oil content 3ppm COD in drain 33 〃 Extraction solvent odor Yes Example 2 A NaSH solution produced in a petrochemical factory and having the composition and properties shown in Table 5 was treated using the same equipment as in Example 1 using 1 NaSH solution and 2 alcohol-based solvents.
- Add 60 ml of ethylhexanol and use the same procedure as in Example 1 to remove acidic oil in the first step, and then in the second step, 30 ml of n-hexane with a concentration of 0.8 of the treated solution obtained in the previous step. The odor of the extraction solvent used was removed, and a treated solution as shown in Table 6, containing almost no acidic oil and no acidic oil odor, was obtained.

In the drain generated by the concentration of this processing solution,
COD was also significantly lower.

Table 5 Composition and properties of NaSH liquid NaSH 22.30wt% Na ₂ S 1.32 〃 Na ₂ CO ₃ 1.40 〃 Na ₂ SO ₃ 0.46 〃 Na ₂ S ₂ O ₃ 0.12 〃 Acidic oil 96ppm COD in drain 220 〃 Na ₂ S/ NaSH (4.25 mol%) Table 6 Composition and properties of treatment liquid NaSH 22.31wt% Na ₂ S 1.33 〃 Na ₂ CO ₃ 1.40 〃 Na ₂ SO ₃ 0.44 〃 Na ₂ S ₂ O ₃ 0.14 〃 Acidic oil 1ppm COD in drain 2 Example with no extraction solvent odor 3 NaSH liquid 1 with the composition and properties shown in Table 7, which was produced in an oil refinery in the same manner as in the previous example, and acidic oil were used in the first step. 60 ml of dibutyl ether, an ether solvent, and n-butyl acetate, an ester solvent, as extraction solvents.
40 ml was placed in the same equipment as in Example 1, and then the second step was carried out using the treated solution obtained in the first step.
0.8 and 100 ml of silicone oil (SH 200-100 manufactured by Toray Silicone Co., Ltd.) as an insoluble solvent, a treatment solution as shown in Table 8 containing almost no acidic oil content, no acidic oil odor, and no extraction solvent odor was obtained.

As in Examples 1 and 2, the amount of COD in the drain resulting from the concentration of the treatment liquid was also extremely low.

Table 7 Composition and properties of NaSH liquid NaSH 25.45wt% Na ₂ S 1.20 〃 Na ₂ CO ₃ 0.46 〃 Na ₂ SO ₃ 0.30 〃 Na ₂ S ₂ O ₃ 0.42 〃 Acidic oil 310ppm COD in drain 650 〃 Na ₂ S/ NaSH (3.39 mol%) Table 8 Composition and properties of treatment liquid NaSH 25.45wt% Na ₂ S 1.21 〃 Na ₂ CO ₃ 0.44 〃 Na ₂ SO ₃ 0.30 〃 Na ₂ S ₂ O ₃ 0.42 〃 Acidic oil content 2 ppm COD in drain 4 Example with no extraction solvent odor 4 As the first step, alkaline waste liquid discharged from an oil refinery and having the composition and properties shown in Table 9 was used at 0.85
Pour 220 ml of isobutyl methyl ketone as an extraction solvent for acidic oil into a three-necked flask equipped with a stirrer, a gas inlet, and an outlet for unreacted gas, and inject H ₂ S gas from the gas inlet while operating the stirrer. After generating a NaSH liquid by blowing Na ₂ S until the content becomes approximately 2 mol % based on the NaSH content, the solvent is separated by a standing method, and as shown in Table 10, most of the acidic oil content is present. A NaSH solution containing no acidic oil and no bad odor caused by acidic oil was recovered.

Next, in the second step, in order to remove the trace amount of extraction solvent odor (isobutyl methyl ketone odor) remaining in the recovered solution from the first step, 0.8 of this recovered solution and 30 ml of n-heptane used for the fifth time were added as an insoluble solvent. The mixture was placed in the same apparatus as in Example 1, stirred for 5 minutes, and then the solvent was separated by a standing method to obtain a recovered liquid from which the extraction solvent had been removed as shown in Table 11.

In this recovered liquid, as in Examples 1 to 3, the COD in the drain generated by concentration was significantly lower than that of the recovered liquid in the first step (Table 10).

Table 9 Composition and properties of alkaline waste liquid NaOH 15.90wt% Na ₂ S 5.60 〃 Acidic oil content 6400ppm Table 10 Composition and properties of recovered liquid in the first step NaSH 25.07wt% Na ₂ S 0.82 〃 Na ₂ CO ₃ 0.89 〃 Na ₂ SO ₃ 0.10 〃 Na ₂ S ₂ O ₃ 0.07 〃 Acidic oil content 3ppm COD in drain 35 〃 Extraction solvent odor Yes Na ₂ S/NaSH (2.35 mol%) Table 11 Composition and properties of recovered liquid NaSH 25.07wt% Na ₂ S 0.81 〃 Na ₂ CO ₃ 0.90 〃 Na ₂ SO ₃ 0.12 〃 Na ₂ S ₂ O ₃ 0.08 〃 Acidic oil content 3ppm Drain COD 5ppm Extraction solvent odor None These examples are merely examples for specifically explaining the present invention. It goes without saying that the present invention includes many changes and improvements within limits, and does not limit the technical idea of the present invention.

As explained above, in the first step of the present invention, one or more of ketone-based, alcohol-based, ether-based, and ester-based solvents are added to the alkaline hydrosulfide solution or its production reaction system produced in a petroleum-related factory. After treating or recovering the alkali hydrosulfide solution by adding and dispersing an extraction solvent, in the second step, the alkali hydrosulfide solution is treated by adding and dispersing an insoluble solvent to the alkali hydrosulfide solution treated or recovered in the first step. This is a method for treating or recovering an alkali hydrosulfide solution, which is characterized by removing a trace amount of acidic oil dissolved in the alkali solution and preventing the extraction solvent from being mixed with the alkali hydrosulfide solution.

According to the method of the present invention, the following effects can be achieved.

A high-grade alkaline hydrosulfide solution containing almost no dissolved acidic oil can be obtained, and the quality of the concentrated product is significantly improved.

Since an alkaline hydrosulfide solution is obtained that removes the bad odor and solvent odor caused by acidic oil, it is possible to significantly improve the working environment by preventing environmental pollution caused by bad odor and solvent odor, and its social effects are It is remarkable.

The COD in the evaporative drainage generated in the concentration process of alkali hydrosulfide solution is significantly reduced, which not only simplifies the pollution equipment required for drainage treatment but also significantly reduces operating costs, which has great social and economic effects. be.

Conventional pollution treatment equipment can be reused and no special treatment equipment is required, further increasing the economic effect.

Claims (1)

[Claims] 1. From one or more of ketone, alcohol, ether, and ester solvents that are sparingly soluble or insoluble in water to the production reaction system of an aqueous alkali hydrosulfide solution or aqueous alkali hydrosulfide solution produced in a petroleum-related factory. a first step of treating or recovering the alkali hydrosulfide aqueous solution by adding and dispersing an extraction solvent; The second step is to add, disperse and process.
A method for treating or recovering an aqueous alkali hydrosulfide solution, which comprises removing acidic oil dissolved in the aqueous alkali hydrosulfide solution and preventing the extraction solvent from being mixed with the aqueous alkali hydrosulfide solution.