JPH11157811A - Production of sulfur dioxide and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically, favorably and stably supply the sulfur dioxide substantially free from impurity, especially nitrogen oxides (NOx ), and having >=99.9% purity with a convenient device. SOLUTION: In the production method of the sulfur dioxide, sulfur is allowed to react with oxygen by blowing a gaseous oxygen having >=95 vol.% oxygen concn. into a liq. sulfur bath kept at the temp. within a range of auto-ignition temp. The oxygen obtained by a pressure swing adsorption method by using an oxygen-containing mixed gas as a starting material and air is used as the mixed gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing sulfur dioxide by a reaction between oxygen gas and sulfur, and an apparatus for carrying out the method. For more information,
The present invention relates to a method and an apparatus for producing sulfur dioxide by a so-called submerged combustion method in which oxygen gas is blown into sulfur kept in a liquid state by heating to burn sulfur in the liquid.

[0002]

2. Description of the Related Art Conventionally, methods for producing sulfur dioxide include:
It is known to produce a gas containing sulfur dioxide by burning sulfur and to separate sulfur dioxide therefrom. For example, U.S. Pat. No. 2,726,933, Japanese Patent Publication No. 52-48597, and the like disclose a method in which oxygen-containing gas, for example, air is blown into molten sulfur heated within a spontaneous ignition temperature range to burn sulfur in a liquid phase. How to do this is shown.

In Japanese Patent Publication No. 52-48597, the amount of heat generated during the combustion reaction of sulfur is removed by the latent heat of vaporization of sulfur.
A method is disclosed in which gaseous sulfur entrained in generated sulfur dioxide is cooled by a condenser to form liquid sulfur and returned to molten sulfur to produce sulfur dioxide.

[0004]

In the above-described method, when oxygen gas is used instead of air during the sulfur combustion reaction, equipment such as a blower and a burner can be simplified, and the cost can be reduced. An advantage is obtained that is advantageous. However, when the concentration of impurities in oxygen gas is high,
There is a problem that a large amount of by-products resulting from impurities is generated and the purity of sulfur dioxide in the reaction product gas is reduced.

An object of the present invention is to provide sulfur dioxide substantially free of impurities, particularly nitrogen oxides (NO _x ). Thus, sulfur dioxide having a purity of 99.9% or more can be obtained by a simple apparatus. It is to provide a stable supply economically.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, have maintained the concentration of nitrogen in the oxygen gas used in the combustion of sulfur at a value lower than 5% by volume. As a result, they have found that the above problem can be solved, and have reached the present invention.

That is, according to the method for producing sulfur dioxide of the present invention, oxygen gas having an oxygen concentration of 95% by volume or more is blown into a bath of liquid sulfur maintained at a temperature within a spontaneous ignition temperature range. And reacting with.

In the present invention, oxygen gas having an oxygen concentration of 95% by volume or more, that is, a nitrogen gas having a low nitrogen concentration is used as the oxygen gas blown into the liquid sulfur bath. and even when the oxygen gas were reacted, NO _X is less likely to occur a problem that a by-product in a large amount due to the nitrogen. Thus sulfur dioxide which is produced is not substantially free of NO _X, agricultural fumigants, high purity, such as pesticides, preservatives preservative fruits and vegetables, fungicide for food processing It is very useful in the field where is required.

As the oxygen gas used in the present invention, liquid oxygen, cylinder-filled oxygen, pressure oscillation type adsorption method (PS
A) The oxygen gas obtained by the PSA method is preferably used, but is not limited thereto. In any of the exemplified oxygen gases, a trace gas other than nitrogen, for example, carbon dioxide, argon, neon, or the like may be contained as an impurity, but components other than nitrogen are substantially included in the sulfur dioxide generation reaction. Since it has no influence, it shall be regarded as oxygen gas.

Here, the PSA method means that a mixed gas containing oxygen is injected into an adsorption tank filled with a filler (adsorbent) such as a zeolite molecular sieve at a pressure higher than the atmospheric pressure, and nitrogen in the mixed gas is removed. In this method, oxygen with high purity is obtained as a non-adsorbed gas by adsorption and removal, and the pressure is reduced to below atmospheric pressure to desorb nitrogen to regenerate the adsorbent. This P
The SA method includes a so-called low-pressure method and a high-pressure method. In the low-pressure method, a mixed gas such as air is supplied at a pressure higher than atmospheric pressure to 2 kg / cm ² G
In this method, the adsorbent is introduced into the adsorption layer at a pressure of less than (1.96 × 10 ⁵ Pa), and nitrogen is desorbed under reduced pressure at a pressure of 100 mmHg to 400 mmHg to regenerate the adsorbent. on the other hand,
The high-pressure method uses a mixed gas such as air at 2 kg / cm ² G
(1.96 × 10 ⁵ Pa) or more and 8 kg / cm ² G (7.
In this method, the adsorbent is introduced into the adsorbent layer at a pressure of 85 × 10 ⁵ Pa or less, and the adsorbent is regenerated by desorbing nitrogen under reduced pressure at a pressure of about atmospheric pressure. Usually, in the PSA method, since each operation is repeatedly performed with a phase shift using two or more adsorption tanks, high-purity oxygen gas (having an oxygen concentration of 95%) is continuously obtained.
% By volume or more of oxygen gas) can be easily obtained.

Further, the apparatus for producing sulfur dioxide of the present invention comprises:
A pressure-oscillating adsorption device for processing a mixed gas containing oxygen to produce oxygen gas, and reacting oxygen gas obtained by the pressure-oscillation adsorption device with liquid sulfur contained therein to obtain sulfur dioxide And a reactor for producing

As described above, in the pressure vibration type adsorption apparatus, high-purity oxygen gas having a low nitrogen concentration can be easily obtained from a mixed gas such as air. Therefore, in the manufacturing apparatus having the above structure can be reacted with high purity oxygen gas and liquid sulfur, it is possible to obtain a low reaction product of NO _X concentration.

In the above-mentioned production apparatus, it is preferable that oxygen gas obtained by the pressure vibration type adsorption apparatus is blown into liquid sulfur. If the oxygen gas is blown into the liquid sulfur, the contact time between the oxygen gas and the liquid sulfur increases, and most of the supplied oxygen gas can be reacted with the liquid sulfur.

Further, the supply of liquid sulfur to the reactor is as follows:
Although it may be continuous or batchwise, the sulfur dioxide is continuously supplied to the reactor by liquid sulfur supply means in an amount corresponding to the sulfur consumed by the reaction. It is preferable when the target is mass-produced in large quantities.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the method for producing sulfur dioxide of the present invention and a production apparatus used for the method will be specifically described below with reference to FIG.

The above-described production apparatus is generally constituted by including a PSA oxygen gas generator X, a reactor 14, a cooler 21, and a liquid sulfur supply unit 18A. That is, in the manufacturing apparatus, the oxygen gas generated by the PSA oxygen gas generator X is supplied to the reactor 14, where the oxygen gas and the liquid sulfur are reacted,
Is removed unreacted sulfur gas by the cooler 21, the sulfur dioxide is configured so as to obtain substantially free of NO _X. On the other hand, the amount of sulfur reduced by the reaction is supplied to the reactor 14 from the liquid sulfur supply device 18A,
It is configured so that sulfur dioxide can be produced continuously. The PSA oxygen gas generator X shown in FIG.
Is an apparatus suitable for producing oxygen by a so-called high-pressure method.

The PSA oxygen gas generator X has two adsorption tanks A and B filled with a zeolite molecular sieve as an adsorbent, and the adsorption tank A is compressed by a compressor 1 to 4 kg / cm ² G ( Air pressurized to 3.92 × 10 ⁵ Pa) is introduced via the valve 3 (pressurizing step).
The air is converted into a gas (enriched oxygen gas) having an increased oxygen concentration by adsorbing and removing nitrogen gas by the adsorbent, and is stored in the enriched oxygen gas storage tank C via the valve 9 (adsorption step). Note that, in practice, even in the pressure increasing step, the nitrogen gas in the air is slightly adsorbed and removed by the adsorbent. However, in the present embodiment, the pressure of the adsorption tank A becomes a constant value, and the adsorption and removal of nitrogen is constantly performed. The state in which the process is performed is referred to as an adsorption process. Further, when the adsorption in the adsorption layer A has been completed, the adsorbent is regenerated by depressurizing and desorbing to atmospheric pressure via the valve 4 (regeneration step). For about 10 to 20 seconds at the end of this regeneration step, a part of the concentrated oxygen gas flows back from the gas storage tank C through the valves 10 and 13 to wash the adsorption tank A (washing step).

The above four steps are one cycle for the adsorption layer A, and this one cycle is performed in about 50 to 70 seconds, and this cycle is repeated.

On the other hand, in the adsorption tank B, as in the case of the adsorption layer A, the production of oxygen gas is carried out by repeating this cycle with four steps of a pressure increasing step, an adsorption step, a regeneration step and a washing step as one cycle. However, the steps in the adsorption layer A and the steps in the adsorption layer B are performed out of phase so that oxygen can be continuously produced in the entire PSA oxygen gas generator X. That is, in the stage where the pressure increasing step and the adsorption step are performed in the adsorption layer A, the regeneration step and the cleaning step are performed in the adsorption layer B, and conversely, the regeneration step and the cleaning step are performed in the adsorption layer A. At this stage, in the adsorption layer B, the pressure increasing step and the adsorption step are performed. Thus, PSA
In the oxygen gas generator X, by alternately producing oxygen gas by the adsorption layer A and the adsorption layer B, oxygen gas can be continuously produced as a whole of the apparatus X. Oxygen gas can be supplied as desired. In order to efficiently produce oxygen gas, in the PSA oxygen gas generator X having two adsorption layers, the total time of the pressure increasing step and the adsorption step and the total time of the regeneration step and the cleaning step are substantially the same time. It is preferable that

Although the PSA oxygen gas generator X for producing oxygen gas by the high-pressure method has been described above, the PSA oxygen gas generator X for producing oxygen gas by the so-called low-pressure method in the sulfur dioxide producing apparatus of the present invention. May be adopted. As shown in FIG. 2, the basic configuration of the PSA oxygen gas generator X for producing oxygen gas by the low pressure method is substantially the same as that of the high pressure method. However, in the regeneration step by the low pressure method, it is necessary to forcibly make the pressure in the adsorption layers A and B lower than the atmospheric pressure. Is used.

In the reactor 14, which reacts oxygen with sulfur to produce sulfur dioxide, the temperature at which the spontaneous ignition temperature of sulfur, that is, 232.degree.
Liquid sulfur is maintained which is kept in a temperature range of 0 ° C, preferably 345 ° C to 440 ° C, particularly preferably 370 ° C to 430 ° C. Further, a blow pipe 15 for blowing high-concentration oxygen gas from the concentrated oxygen gas storage tank C into liquid sulfur is attached to the reactor 14. That is, the blowing pipe 15 has a plurality of blowing holes 16 formed at a distal end thereof, a base end connected to the concentrated oxygen gas storage tank C, and a high pressure generated by the PSA oxygen gas generator X. Concentrated oxygen gas is configured to be supplied to the reactor 14.

The high-concentration oxygen gas supplied to the reactor 14 is not limited to that obtained by the PSA method, but may be liquid oxygen, cylinder-filled oxygen, etc., and the design can be changed as appropriate. is there.

The high-concentration oxygen fed from the PSA oxygen gas generator X through the blowing pipe 15 is blown into the liquid sulfur from the blowing hole 16 in a bubble form, and sulfur dioxide is produced by a combustion reaction between the sulfur and oxygen. Is done. In this embodiment, since the oxygen concentration in the liquid sulfur is supplied high concentration oxygen gas or 95 vol%, it is possible to produce a sulfur dioxide containing no NO _X substantially. Further, when oxygen gas is supplied into the liquid sulfur and in a bubble state, most of the supplied oxygen gas can be reacted with the liquid sulfur.

Further, a supply nozzle corresponding to the amount of sulfur consumed by the reaction is supplied from a liquid sulfur supply device 18A equipped with a liquid sulfur tank 17 and a pump 18 in which a spontaneous ignition temperature (232 ° C.) or less is maintained. Reactor 1 via 19
4 resupplied.

The generated sulfur dioxide gas enters the cooler 21 through the upper space 20 of the reactor 14. This cooler 2
In the example shown in FIG. 1, a vertical multi-tube heat exchanger is used, and includes a cooling pipe 22 and a jacket 23. Reactor 14
The sulfur dioxide gas containing sulfur vapor generated in
2 flows in an upward direction, is cooled by a cooling medium contained in a jacket 23, and is condensed and separated into a liquid state of sulfur vapor contained therein, and is then taken out as a product from a sulfur dioxide gas outlet 24.

On the other hand, the liquid sulfur condensed in the cooler 21 naturally flows down the pipe wall and falls into the liquid sulfur bath of the reactor 14. The cooler 21 and the sulfur dioxide gas outlet 2
Between the four, a mist separator for separating sulfur from the droplets may be provided. The reactor 14 is provided with a jacket 25, which prevents the solidification and adhesion of sulfur to the inner wall of the reactor 14 at the start of the operation by the heat transfer medium flowing through the jacket 25, and also assists the formation of sulfur dioxide. Heating and cooling may be performed so that a part of the generated heat can be removed. Of course, the design of the cooler 21 can be changed as appropriate.

The sulfur dioxide thus produced is substantially free of NO _X and has high purity such as agricultural fumigants, insecticides, preservatives for preserving fruits and vegetables, and fungicides for food processing. Very useful in the required fields.

[0028]

The present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to these examples.

[0029]

Embodiment 1 As oxygen gas, oxygen in a cylinder (oxygen concentration 9
9.8%) and the reaction temperature was 366 ° C. and 39 ° C., respectively.
Oxygen gas was blown into liquid sulfur kept at 4 ° C. and 404 ° C. to cause a reaction between oxygen and sulfur. Oxygen gas is blown at 1 liter / min into a 5-liter reactor designed so that the liquid depth of the injection hole in about 2 liters of liquid sulfur is 37 cm, and the temperature of the cooler is raised to 130 to 150 ° C. The production of sulfur dioxide was carried out. The thus obtained sulfur dioxide purity, produced NO _X concentration, and the results of examining the oxygen reference reaction rate shown in Table 1. Here, the oxygen-based reaction rate is
The ratio of oxygen that has reacted with sulfur in the oxygen supplied to the reactor on the basis of the capacity.

[0030]

[Table 1]

[0031]

Embodiment 2 As oxygen gas, high-concentration oxygen obtained by a PSA method was used. That is, two adsorption tanks each having a diameter of 80 mm and a height of 1200 mm were each filled with a 5A type zeolite molecular sieve manufactured by Bayer, and a gas storage tank having the same capacity as the adsorption tank was provided on the outlet side of the adsorption tank. 4.0kg / c
Air pressurized to a pressure of m ² G (3.92 × 10 ⁵ Pa) was introduced, and four steps of a pressurization step of 10 seconds, an adsorption step of 25 seconds, a regeneration step of 25 seconds, and a cleaning step of 10 seconds were performed in each adsorption tank. One cycle was performed, and this cycle was repeated with the phase of each adsorption tank shifted. The regeneration of the adsorbent was carried out by opening one valve at the bottom of the adsorption tank and discharging a desorption gas containing nitrogen as a main component to the atmosphere. The washing step was performed at the end of the regeneration step by causing the concentrated oxygen gas to flow backward from the gas storage tank to the released adsorption tank for 10 seconds. As a result of the above operation, high-concentration oxygen having an oxygen concentration of 97.0% was obtained at 100 liter / hour.

The oxygen gas thus obtained was blown into liquid sulfur maintained at a reaction temperature of 400 ° C. to react oxygen with sulfur. Specifically, the position of the blow hole is 7 cm, 22 cm, 3 cm from the liquid surface of the liquid sulfur (liquid depth).
The reactor was charged with liquid sulfur in a 5-liter capacity reactor in four stages so as to be 7 cm and 41 cm, and in each case, oxygen gas was blown into the reactor at 1 liter / minute, and the temperature of the cooler was set to 130 to The production of sulfur dioxide was carried out at 150 ° C. The sulfur dioxide purity thus obtained,
Table 2 shows the results of examining the generated NO _X concentration and the oxygen-based reaction rate.

[0033]

[Table 2]

[0034]

Comparative Example 1 An oxygen gas containing 7% of nitrogen and 93% of oxygen was prepared. In Example 1, sulfur dioxide was produced at a reaction temperature of 404 ° C. In the sulfur dioxide obtained in this way, sulfur dioxide purity, the oxygen reference reaction rate was the same as in Example 1, contained 150ppm of NO _X.

[0035]

According to the so-called submerged combustion method of sulfur, in which oxygen gas is blown into liquid sulfur maintained at a temperature within a spontaneous combustion temperature range, so-called sulfur in liquid combustion, nitrogen is added at a concentration lower than 5% by volume. when using oxygen gas containing, it is possible to produce a sulfur dioxide containing substantially no nO _X is an impurity in the sulfur dioxide.

In this case, if high-concentration oxygen having an oxygen concentration of 95% by volume or more obtained by the PSA method is used as oxygen gas, sulfur dioxide can be industrially advantageously produced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an apparatus for producing sulfur dioxide according to the present invention.

FIG. 2 is a diagram illustrating another example of the sulfur dioxide producing apparatus according to the present invention.

[Explanation of symbols]

 A, B adsorption tank C concentrated oxygen gas storage tank 14 reactor 15 blowing pipe 17 liquid sulfur tank 21 cooler

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kenji Hamada 346-1 Miyanishi, Harima-cho, Kako-gun, Hyogo Pref.

Claims (6)

[Claims] 1. An oxygen gas having an oxygen concentration of 95% by volume or more is blown into a bath of liquid sulfur maintained at a temperature within a spontaneous ignition temperature range to react oxygen and sulfur. Method for producing sulfur dioxide. 2. The method according to claim 1, wherein an oxygen gas obtained by a pressure vibration adsorption method using a mixed gas containing oxygen as a raw material is used as the oxygen gas. 3. The method according to claim 2, wherein air is used as said mixed gas. 4. A pressure vibration type adsorption device for processing a mixed gas containing oxygen to generate oxygen gas, and a liquid sulfur contained in the pressure vibration type adsorption device which is obtained by the pressure vibration type adsorption device. An apparatus for producing sulfur dioxide by reacting the same. 5. The sulfur dioxide producing apparatus according to claim 4, wherein the oxygen gas obtained by the pressure vibration adsorption apparatus is blown into the liquid sulfur contained in the reactor. 6. The apparatus for producing sulfur dioxide according to claim 4, further comprising a liquid sulfur supply means for replenishing the reactor with an amount of sulfur corresponding to the sulfur consumed by the reaction.