JPH0222108A - Production of sodium hydrosulfide - Google Patents

Abstract

PURPOSE:To continuously obtain sodium hydrosulfide in high stability by reaction using a static mixer between a high-concentration sodium hydroxide solution and high-concentration hydrogen sulfide-contg. gas. CONSTITUTION:An industrially produced high-concentration sodium hydroxide solution and a high-concentration hydrogen sulfide-contg. gas generated mainly from petroleum refining processes are made to flow in a parallel flow fashion into a static mixer at the molar ratio of the hydrogen sulfide to the sodium hydroxide (1.0-2.0):1 and allowed to react so as to be ca. 75-110 deg.C in the outlet temperature of the static mixer. Thence, the resulting reaction product is either directly fed into the bottom of a separator or into the bottom of such separator connected to the static mixer with a large-diameter piping, thus obtaining the objective sodium hydrosulfide. Said static mixer may be such an agitator that many baffle plates are set in the piping channels and such actions as division, inversion and conversion are adequately made during fluid passage through the pipings.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention involves reacting a highly concentrated caustic soda solution with a gas containing highly concentrated hydrogen sulfide in a static mixer, and continuously producing a high-concentration sodium hydrogen sulfide water bath. Concerning how to raid.

Sodium hydrosulfide is used in a wide range of fields as a depilatory agent, pulp digester, hair removal accelerator, and thiolating agent.Recently, pps (polyphenin/sulfide) has been in the spotlight, and its sulfiding agent As a result, high concentration and high purity sodium hydrogen sulfide will be required.

(Prior Art and Problems to Be Solved) Conventionally, two methods have been used to produce sodium hydrogen sulfide: a batch method and a continuous method using a reaction column method.

The batch method is a method for producing sodium hydrogen sulfide by blowing hydrogen sulfide-containing gas into the caustic soda bath sludge in a reaction tank. This method usually requires multiple large reaction vessels, which increases the size of the equipment, and the caustic soda solution has a high temperature.
a degree and the hydrogen sulfide gas concentration was increased (approximately 80 to 9
8 mol%), the absorption and reaction of hydrogen sulfide gas proceeds rapidly at the beginning of the reaction, and the stirring and mixing of the liquid is difficult, making it difficult to complete the reaction uniformly. It's a shortcoming.

In addition, the reaction column method is a method of manufacturing sodium hydrogen sulfide by using a so-called packed column, causing a caustic soda solution to flow down from the top, and blowing hydrogen sulfide gas into the bottom. In this method, the reaction within the column is sufficient and the operation is relatively stable, but if the reaction does not proceed to the end and unreacted sodium sulfide (NAKS) is produced, Na! S solidifies and accumulates in the reaction tower, creating the risk of blockage, requiring time and cost for regeneration.Also, the reaction between a highly concentrated caustic soda solution and a highly concentrated hydrogen sulfide is extremely exothermic. The difficulty in continuous operation is that the temperature within the reaction system tends to rise abnormally.

(Means and effects for solving the problem) The present inventor has made extensive studies to overcome the conventional drawbacks of continuously producing sodium bisulfide from high concentration caustic soda and high concentration hydrogen sulfide-containing gas. As a result, the high concentration caustic soda solution and the high concentration hydrogen sulfide-containing gas are reacted using a static mixer, the installation of the static mixer is specified, and the gas-liquid multiphase flow exiting the static mixer is statically controlled. A new method of producing sodium hydrogen sulfide that enables stable continuous operation that easily removes unreacted sodium sulfide even if unreacted sodium sulfide is generated due to incorrect operation, by connecting a mixer and a separator and flowing it through a 9' group pipe. They discovered a method and completed the present invention.

That is, the gist of the present invention is a continuous method for producing sodium hydrogen sulfide, which is characterized in that highly concentrated caustic soda bath sludge and highly concentrated hydrogen sulfide-containing gas are caused to flow in parallel through a static mixer and react. Hydrosulfurization, further characterized in that a plurality of the static mixers are installed in series and/or in a water cooling device, and that the reactant is sent to the bottom of a separator connected to the static mixer by a large-diameter pipe. It consists in a method for continuous production of soda.

Specifically, industrially produced high-yield caustic soda bath and gas containing high concentration hydrogen sulfide mainly generated from petroleum refining processes are used at a concentration of 1.0 hydrogen sulfide per mole of caustic soda.
~2.0 moles, preferably about 1.2-1.5 moles, are cocurrently fed into a static mixer at an outlet temperature of about 75-110°C as shown in the following reaction equation: After a two-step reaction, the reactants can be directly fed into the bottom of the separator, or connected to a static mixer through a pipe with a specified diameter and shape (hereinafter referred to as large diameter size). This invention relates to a continuous method for producing sodium hydrogen sulfide, which is characterized in that it is fed into the bottom.

First stage reaction 2NaOH+ Has -4NAKS + 2H20+
1α5 k cal/l ・mol 2nd stage reaction Na2E3 + H2S →2Na8H+ 1! L7
RoaVf @molHereinafter, the present invention will be explained in more detail.

The high-concentration caustic soda solution used in the present invention can be industrially produced, and its m degree is about 50 to
Concentrations as high as 60 wt%, preferably about 40-50 wt% can be used. Furthermore, when regenerating the absorption liquid used to remove the highly concentrated hydrogen sulfide-containing gas used in the present invention, which is usually generated from the oil refining and desulfurization process, the hydrogen sulfide-containing gas released is used. However, the present invention is not limited thereto, and any material having a degree of a of about 70 to 99 mol, preferably about 80 to 98 mol can be used.

The gas containing high-grade hydrogen chloride from the petroleum refining desulfurization process is hereinafter referred to as Acrado gas.

The molar ratio of caustic soda and hydrogen sulfide is 1.0 to 2.0 mol of hydrogen sulfide per 1 mol of caustic soda, preferably Fl
It is used in a proportion of 1.2 to 1.5 moles.

Therefore, the acid gas is supplied in an amount of about 1.0 to 2.0 times, preferably about 1.2 to 1.5 times the stoichiometric amount to the highly concentrated caustic soda bath sludge.

If the amount of acid gas supplied is small, the reaction will not proceed to the end and will be incomplete, producing unreacted products (Na snow 8).
This accumulates in the static mixer and causes blockages. Moreover, if the supply amount is large, a large amount of unreacted hydrogen sulfide gas will be generated, which is uneconomical.

The static mixer used in the present invention has a large number of elements (baffle plates, etc.) fixedly installed in the pipe, and as the fluid passes through the pipe, it performs dividing, reversing, and converting actions. A pipe agitator can be used in which this is carried out satisfactorily.

When contact is the rate-determining step in the reaction, such as this reaction between caustic soda solution and acid gas, the static mixer uses the above-mentioned actions to sufficiently mix and stir the fluid in the pipes, completing the reaction quickly and efficiently. product can be obtained.

Any type of mixer may be used as long as the above-mentioned effects are good, and a so-called homemade mixer may be used, but in general, a commercially available static mixer may be used. Commercially available products include, for example, those shown in Figures 2 to 5.
As shown in the figure (1) Kenica m1xe
r (Ott Vervieba-Δgesellschaft, Leonberg)
, domestically produced by Noritake Company Limited [
Static Mixer” (No. 21), f21 SMV
m1xer (8u1zer, Winterhur
), Domestic products include Sumitomo Heavy Industries Co., Ltd. “Sulzer mixer” (Figure 3), 131 SMX m1xe
r (5ulzer, Winterhur) (4th
Figure), (41N-8haped pipe m1xer
(Bran & Lubbe, Norderat
edt) (Figure 5) etc. Highly concentrated caustic soda solution and acid gas are passed through a static mixer in parallel flow, but multiple static mixers can be arranged in series to ensure sufficient reaction. When using multiple static mixers, use acid gas
- It is preferable to flow it in parts at the inlet of the valley static mixer. This is because the division narrows the region that becomes a slag flow (a flow containing many air bubbles in the fluid slug part in a gas-liquid multiphase flow). This is due to the flow rate fluctuation of Amirad gas. This is because pressure fluctuations can be suppressed.

The reaction temperature in the static mixer is approximately 60 to 120°C, preferably approximately 75 to 110°C at the exit temperature using a water cooling device.
controlled by. If the reaction heat is too high, the materials used will be severely corroded, which is undesirable.

The temperature of the static mixer can be controlled, for example, by placing the static mixer in a water tank and adjusting the cooling water in the water tank.

The reactants reacted in the static mixer flow through large-diameter piping and are sent to the bottom of the separator. Large-diameter piping is used to prevent the flow from becoming a slug flow region due to gas-liquid multiphase flow, and the piping diameter is larger than the size of the static mixer, and its diameter is determined by the g/gas ratio and the flow rate in each pipe. is usually about 5 to 2 inches or more, preferably about 1 inch or more, 25.
It is 4z (10 inches) or less. For example, the flow rate of high concentration caustic soda is 60 to 120 t/h.

Acid gas flow rate: 58 to 77 Nm"/h, static mixer pressure: approximately 18 to 2.0 kl?/αJ) 1
At an outlet pressure of approximately 16-1.6 kg/α2G.

Large diameter piping is approximately 2.54~181crR (1~
1″A inch) or more, preferably 2.54~5.08c
m (1 to 2 inches) 8 degrees is good.

It is desirable that the piping be simple and have a gentle downward slope. If the diameter of the piping is small or the piping is complicated, the range of flow rate and pressure fluctuations will increase due to slug flow in the gas-liquid multiphase flow, making control difficult. Also,
If a movable mixer is used instead of a static mixer, electrical equipment and the like are required as a drive system, which is disadvantageous in terms of equipment costs, and sufficient stirring cannot be achieved.

After the reaction, sodium hydrogen sulfide and unreacted gas (excess hydrogen sulfide gas and impurity gas) are separated into gas and liquid by a separator, and the unreacted gas is released. The resulting sodium sulfide solution is drawn out while controlling the liquid level with a level gauge and a control valve, cooled in a cooler, and transferred to a product tank in the normal process to be manufactured into a product.

(Effects of the invention) By using a static mixer, temperature control etc. can be easily performed, and high concentration (
About 50 to 60 wt% Na5H. ), high-purity sodium hydrogen sulfide can be produced continuously and efficiently.

If less than the equivalent amount of hydrogen sulfide gas is blown into the caustic soda solution due to incorrect operation, etc., a large amount of sodium sulfide will be generated and solidify, so when using the conventional batch method or reaction column method, However, in the method of the present invention, the entire state ink mixer can be installed inside the water cooling device, and this water cooling device It is easy to adjust the temperature above the melting point of soda sulfide by blowing steam into it, which solves the solidification blockage of soda sulfide.

Furthermore, by making the pipe connecting the mixer and separator large in diameter, the problem of slug flow in gas-liquid multiphase flow is solved, and control becomes easy without fluctuations in flow rate and pressure. The present invention will be fully explained with reference to and comparative examples.

Examples 1-2 As shown in the accompanying drawings, a first-stage static mixer 7 and a second-stage static mixer 8 are connected in series in a water tank 16 so that the reaction temperature inside the mixer can be controlled. Second stage static mixer 8 and separator 9
Highly concentrated caustic soda as a raw material from pipe 1 and a part of acid gas from pipe 2 are connected to a device connected at a downward slope of 5 degrees using a large-diameter straight pipe 15 with a diameter of 581 era (1% inch). (approximately 50%) t-Flowed in parallel to the first stage static mixer 7, and the acid gas residue V from the pipe line 2 was flowed to the second stage static mixer 8 for reaction.

The sodium hydrogen sulfide liquid and unreacted gas coming out of the second stage static mixer flow through a large-diameter straight pipe 15, and are separated into gas and liquid at the separator bottom 9, and sodium hydrogen sulfide is obtained from the pipe S drawn out from the bottom.

The first-stage static mixer and second-stage static mixer used were the same, with a diameter of 2.54 cm.
Length: 82.5 mm, number of elements: 18, maximum processing capacity: 1
20t/h Kenica Mixer (manufactured by Noritake Company Limited) f: User.

Examples 5 to 5 The entire amount of acid gas from the pipe line 2 is passed to the first stage static mixer 7 in parallel flow, and the same method as in Examples 1 to 2 is carried out except for the following.

As the results of Examples 1 to 5, Table 1 shows the composition of high-abdominal soda, Table 2 shows the composition of acid gas, Table 5 shows the operating conditions, and Table 4 shows the high concentration and high purity produced. The composition of sodium hydrosulfide is shown.

Comparative Example 1 This was carried out in the same manner as in Examples 1 and 2, except that an inch straight pipe was used instead of the large diameter straight pipe 15 in Examples 1 and 2.

As a result, the flow in the straight pipe becomes a slug flow due to a gas-liquid multiphase flow, and the flow rate and pressure fluctuate greatly, making control difficult. Therefore, some unreacted substances (Na1B) are generated.

Table 1 Specific gravity (5074°C) 1.5066 Table Examples 6 to 7 The same method as Examples 1 to 2 was used except that the entire amount of acid gas was flowed in parallel to the second stage static mixer from pipe 2. Let's go.

Table 5 shows the operating conditions, and Table 6 shows the composition of the high concentration sodium hydrogen sulfide produced.

6 Table 8...Second stage status 9...Separator 10...Condenser 11...Cooler 12...Thermometer 15...Liquid level gauge 14...Control valve 15...Large Diameter piping 16...water tank mixer 1'g Figures 2 to 5 are partial cross-sectional views of a static mixer that can be used in the present invention.

1... High-abdominal soda leakage pipe line 2... High-altitude sulfide water 'lA'M gas (acid gas)
辂路5...Soda hydrosulfide (semi-finished product) 4...Cooling water 5...Steam 6...Filter 7...First stage static mixer

Claims (4)

[Claims] (1) A method for continuous production of sodium hydrogen sulfide, characterized in that a highly concentrated caustic soda solution and a highly concentrated hydrogen sulfide-containing gas are caused to flow in parallel through a static mixer and react. (2) The method for continuously producing soda hydrogen sulfide according to claim 1, wherein a plurality of static mixers are installed in series. (3) The method for continuously producing sodium bisulfide according to claim 1 or 2, wherein the static mixer is installed and used within a water cooling device. (4) Highly concentrated caustic soda solution and highly concentrated hydrogen sulfide-containing gas are caused to react by flowing them in parallel through a static mixer, and the reactants are sent to the bottom of a separator connected to the static mixer through large-diameter piping. A continuous method for producing sodium hydrogen sulfide, characterized by the following.