JPH01502408A - Method for treating gaseous emissions containing sulfur dioxide using oxygen, and apparatus for using the method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] “Method for the treatment of gaseous emissions containing sulfur dioxide using oxygen; ``Me device'' The object of the present invention is a method for the purification and treatment of gaseous effluents containing sulfur dioxide.

Sulfur dioxide is mainly emitted from fossil fuels, especially heavy petroleum distillates. This cause Other industries that use or consume sulfur or its inorganic compounds, e.g. Industries that produce g-acids by burning sulfur, roasting ores, and certain inorganic salts. Industries such as firing industry and metallurgy industry will be added. Currently, large amounts of gaseous emissions containing sulfur dioxide are being produced. Air emissions are a significant source of pollution, causing significant damage to the environment.

The oxidation of sulfur dioxide by oxygen is slow, and many gaseous emissions treatment techniques describes the absorption of sulfur dioxide by basic compounds in solid form or compounds in the form of aqueous suspensions. As a principle. The solid or liquid compound thus obtained can be mechanically extracted from a gas stream. Separated and then processed if desired. Under these conditions, these The problem is to remove these compounds in an economically and ecologically acceptable manner. still remains.

A second purification method involves oxidizing sulfur dioxide with oxygen or air in an aqueous medium. and the method leads to a usable somewhat dilute sulfuric acid solution.

The certificate of addition to French Patent No. 2.058.158 states that in the first stage, sulfur dioxide Oxygen containing fume is transported by a carrier fluid such as oxygen. and in a second step contacting the fume with a sulfuric acid solution. A method for purifying sulfur dioxide-containing fume is described.

However, this oxidation must be carried out at a rate compatible with the circumstances of industrial operations. In order to There is.

From French Patent No. 2,186.285, sulfuric acid macerate previously oxidized with ozone is A method of contacting a sulfur dioxide-containing gaseous effluent with a dilute sulfuric acid solution in the presence of a Are known.

sulfur dioxide by catalytic catalytic oxidation reactions that produce more or less concentrated sulfuric acid solutions. Purification of gaseous emissions has been the object of many studies.

French Patent No. 2.238.669 discloses that manganese sulfate-containing dilute sulfuric acid and long-term oxidizes gaseous emissions containing oxygen and sulfur dioxide by contacting them with It is stated that

This method theoretically allows the reuse of sulfur dioxide contained in gaseous emissions. However, its practical use poses various problems. The amount of catalyst used is large and The sulfuric acid collected above is relatively dilute and contains a high concentration of impurities derived from the remaining catalyst. contains. To obtain commercially available sulfuric acid from such a process, the catalyst must be removed. one or more purification steps to obtain an acceptable acid concentration; and a concentration step to obtain an acceptable acid concentration. Requires use with. These steps place a heavy burden on the overall economics of the method. let

French Patent No. 2,323,632 discloses that gaseous emissions containing sulfur dioxide A method of treating said effluent in the presence of oxygen or air and a catalyst such as a manganese ore salt. the sulfur dioxide-containing sulfur dioxide obtained after contacting with an aqueous sulfuric acid solution under A diacid produced by subjecting an aqueous acid solution to the action of an oxidation initiator irradiated with ionizing radiation. A method for treating sulfur-containing gaseous emissions has been proposed. The above sulfuric acid aqueous solution is , radioactive isotopes such as 66 (.

13? (Ionizing radiation from aOT lines and leakage lines from charged particle accelerators) irradiated by either a radiation source. According to this method, the gap exceeding 0.95 It is possible to achieve a high degree of sulfuric acid purity while obtaining sulfuric acid with a concentration close to 50%. Why However, the use of this method on an industrial scale is completely impractical due to various serious deficiencies. Because you can't even make a statue. Processing large amounts of sulfuric acid by irradiation is extremely expensive at refinery sites. Requires equipment with significant cost and equipment costs. In addition, X-rays or T The use of wires is dangerous and poses very serious safety issues for workers. do.

Active reactants related to the above findings and contributing to the oxygen oxidation of sulfur dioxide (active 5 pecies) is manganese with an oxidation degree greater than +■ Ion: Considering that it is considered to be anal, it has a very high efficacy exceeding 99%. can be used immediately while using the lowest amount of catalyst and without the need for further reprocessing. An economically acceptable industrial purification method that allows obtaining sulfuric acid solutions of the highest concentration possible. Efforts were made to find a law.

According to the proposed method, the presence of oxygen and a catalyst system mainly composed of manganese salts The purification treatment of gaseous emissions with sulfur H'f4 liquid is described below by contacting sulfur dioxide with oxygen. Catalytic oxidation is carried out using concentrated sulfuric acid in the presence of a system produced by electrooxidation of manganese salt M2. It is characterized by being carried out in an acid catalyst.

When using a solution of magnesium sulfate Mn5Oa + HzO that is not electrolyzed in sulfuric acid, , was found to be unable to oxidize sulfur dioxide. On the other hand, the electrons supplied in the tank decomposition The oxidation of at least 15 moles of SOt per mole has a degree of oxidation greater than + The active reactant produced by the electrooxidation of manganese has a catalytic role. i is recognized.

Also, using air instead of oxygen to oxidize sulfur dioxide is very Provides only modest purification efficiency. When oxygen is replaced with nitrogen, the conversion rate is zero. be. Oxygen refers to oxygen containing at least 80%, preferably at least 90%. means a gas or gas mixture.

, 714 The active reactant in the form of ions is used in the electrolytic oxidation of manganese ions in concentrated sulfuric acid medium. This is how it is generated. The electrochemical production of this active reactant group consists of two separate sulfuric acid in an electrolytic cell with separate compartments. The method is carried out by electrolysis of a sulfuric acid solution of Mn5Oa, HzO. The electrode is For example, a titanium plate coated with platinum is used as an anode, and a platinum plate or steel plate is used as a cathode. The electrode plate may be made of stainless steel plate.

Selection of electrode materials such as lead or titanium coated with precious metals or with lead dioxide is also suitable. It is a type. The potential difference applied between the two electrodes ranges from 1.5 volts to 3 volts. , but a range of 1.8 volts and 2.2 volts is preferred.

The active reactant is prepared continuously or batchwise, and the diacid of the gaseous effluent to be purified. purification treatment cycle of gaseous effluents in an amount selected and determined depending on the amount of sulfur introduced into the Le system. That is, for example, 400 to 10,000 ppo+V(par For a sulfur dioxide content of ts per milliion), the amount of manganese is , 18 to 64 ■ per 12 sulfuric acid for scrubbing , a purification efficiency of over 99% can be obtained.

Oxygen catalytic oxidation of said effluents containing sulfur dioxide is activated electrochemically. It is very advantageously carried out in an oxidation zone prefilled with a concentrated sulfuric acid medium containing a catalyst system. Ru. In the opposite case, the SO□-containing effluent is introduced into the oxidation zone and then the Ml When adding the sulfuric acid medium containing l+, no significant oxidation is observed.

According to one advantageous selection practice, under slight oxygen pressure, preferably 0.2 to It is conceivable to carry out catalytic oxidation of the effluent at I MPa. small amount of ozo The addition of chlorine causes the reaction to take place in the presence of an electrochemically generated active catalytic reaction system. It has been found that the catalytic power of the reaction system for oxygen oxidation of sulfur dioxide-containing emissions can be improved. It was.

Alternatively, catalytic oxidation can be carried out at 40 to 80 μm per hour in oxygen as the R feed fluid. When carried out in the presence of small amounts of ozone delivered on the order of gives a constant oxidation efficiency of the order of %.

Under certain combinations of conditions, when the method is carried out continuously, including various variants, At least the following recirculation can be advantageously carried out.

...i.e. the sulfuric acid medium should be recycled to the oxidation zone and purified if desired. It is possible to recirculate the sulfuric acid medium into the cleaning zone for scraping the effluent. , it is also possible to recirculate the catalyst into the electrolyzer by sulfuric acid injection, and the acid It is even possible to recirculate oxygen into the oxidation zone.

Alternatively, the catalytic oxidation may be carried out continuously in one or more oxidation zones connected in series. is possible, in which case the catalyst system can be introduced intermediately between the respective oxidation zones if desired. or intermediate introduction of ozone between each oxidation zone or catalyst. system and ozone can be introduced intermediately.

The present method for purifying contaminated effluent while obtaining readily available sulfuric acid It may be implemented in various types of equipment as described by way of non-limiting example and shown in the accompanying drawings. Ru.

In the apparatus of Figure 1, an active catalytic reactant M is produced in the anode chamber of the electrolytic cell (2). The sulfuric acid solution containing manganese sulfate is introduced into the electrolytic cell through the tube (1). electric The vapor-chemically activated manganese solution is passed through the sulfuric acid circuit using a metering pump (not shown). (3) is injected. The sulfuric acid solution containing this tag is introduced into the oxidation tower (4). , the column packing consisting of, for example, glass rings or plates, is impregnated and saturated. then pure The sulfur dioxide-containing gaseous effluent (5) introduced into the oxygen stream is combined with a sulfuric acid solution containing It is introduced cocurrently into the oxidation tank. The purified effluent comes from (6) at the bottom of the oxidizer. The extracted and industrially usable sulfuric acid is collected from (7) at the base of the oxidizer.

in two successively connected oxidation zones, with optional recirculation of the sulfuric acid. The method of purification in the presence of ozone can be carried out in the apparatus shown in Figure 2. .

As mentioned above, the device is supplied with (HzS04+Mn5O4) solution in tube (1). It has an electrolytic cell (2) in which the solution produced in the electrolytic cell is passed through the measuring port. The sulfuric acid is introduced into the sulfuric acid supply pipe (3) by a pump (not shown) and led to the first oxidation tower (4a). entered. The ozone-oxygen 0,10□ gas flow is passed through the tube (8) at 1. ! 14/H , SO, is introduced into the pipe (3) carrying it. To be processed (Sow) + output is The liquid medium introduced at the top of the column (4a) and removed at the base of this column is In circuit (9) it is introduced into the top of the second oxidation tower (4b). The emissions themselves are (4b), the available sulfuric acid is discharged from the base of the column by pipe (7). A portion of the concentrated sulfuric acid is extracted from the tube (7), and a portion of the concentrated sulfuric acid is extracted from the tube (7) It is recycled to the first oxidation tower. If desired, the intermediate introduction of catalyst system and ozone can be piped ( 3') from the top of the column (4b).

The process is carried out with oxidation using oxygen and recycling of the catalyst, sulfuric acid and oxygen. In this case, this processing method can be carried out in the apparatus shown in FIG.

The device is a scrubber 0'! J, electrolytic cell (2), oxidation tower ( 4) and has circulation paths for intake and discharge of various fluids. The device also provides oxygen circulation. The process is carried out under pressure by the addition of oxygen (8a). For a simple loop circuit that can have c recompressors if desired when implemented under respond. Furthermore, the device has a sulfuric acid circuit CI (D) corresponding to a simple loop circuit. The sulfuric acid is connected to the circulation path OD for recirculating the catalyst to the decomposition tank (2) and to the head of the scrubber. 04) for recirculation, and the gas to be purified is at the base of the scrubber. The purified gas is introduced into section (5) and recovered at the top (6).

The purification method described above involves the recovery of SO□ in the form of readily available sulfuric acid and the removal of effluents. It is applied to the purification of effluents contaminated with sulfur dioxide, while also acquiring Ru.

Permanent emissions from the pyrolysis of inorganic sulfates to produce their corresponding oxides When processing the sulfuric acid obtained in this method, the sulfuric acid obtained by the method can be advantageously recycled to the preparation process of the cough salt. Can be linked.

Examples of the method of the present invention are shown below, but the invention is not limited to the examples.

Pig-”1-Example 2”- Preparation of catalyst The oxidation of manganese sulfate Mn5Oa, The process is carried out batchwise in an electrolytic cell with rows of anode chambers and cathode chambers; energization is carried out by a stable power source. So I went.

The effective volume of each electrode chamber is the same and is 80 r/.

The anode consists of a platinum plate (titanium Pt/Ti plate), and the cathode consists of a platinum plate. Ru. A voltage of 2.0 +0.2 volts is applied between the two electrodes. Nitrogen stream acts as a liquid flow agitator.

A sulfuric acid solution with a concentration of 36.5% by weight contains 0.1 mol (16.9 g/i!,) of Contains Mn5Oa, HzO, and a solution volume of 60d is electrolyzed in 30 minutes. .

The color of the solution changes from colorless at the start of electrolysis to bright red at the end of electrolysis. r, ry red) and that the current stabilizes after 30 minutes. The end point of the reaction was determined using the apparatus shown in Figure 1.

In the first series of continuous oxidation tests, in the presence of 99.5% pure oxygen, large amounts of The electrical power required to oxidize sulfur dioxide-containing emissions with greater than 99.5% efficiency. Tests were conducted on the amount of vapor-chemically activated manganese.

For a total gas flow of 11 r/h and a contact time of 7 seconds, 1000 pp+n The manganese required to oxidize an amount of SO□ close to V is less than 25 mg/j2 . The sulfuric acid taken has a concentration of 45% by weight. The results obtained are shown in Table 1.

The 502 eA degree at the oxidizer outlet was continuously measured using conductivity analysis.

The purification efficiency is calculated by the following formula: (In the formula, (SO2) I is the concentration of SO□ at the intake of the oxidizer, and (So R is the residual concentration of 302 at the outlet of the oxidizer, compensated by the solubility of SO□ in sulfuric acid. defined according to

(Mn) is the total concentration of manganese in the sulfuric acid solution (oxidation degree of ionic species present in the solution) ).

The mark (X) indicates that the manganese sulfate was not electrochemically activated.

A second one using pure oxygen and a total gas flow rate of 542/hr and a contact time of 30 seconds. In a series of continuous oxidation tests, 32 mg/j2 of manganese was 2000 ppmV ( DSOz 97% 7% oxidized meal was found to be sufficient. double the amount of manganese In this case, it was possible to oxidize 4000 ppmV of SOt at the same conversion rate.

In the latter case, the degree of purification is 95% at SO2 concentrations exceeding 4000 ppmV. It has fallen further below.

In this series of tests, the sulfuric acid taken has a concentration of 50% by weight.

Strategy” L theft (SO2). 8 indicates the concentration of SO, = (SO□) l-(so□), NRh -' indicates the value per hour.

Number of moles of manganese The results of this test show that the SO□ contained in the exhaust gas is oxidized with pure oxygen in concentrated sulfuric acid medium in the presence of The significance of the numerical value indicates the catalytic effect of manganese on the oxidation reaction, and the optimization of the oxidizer Under conditions where no manganese was introduced, the oxidized SO It was a mole. The conversion obtained varies depending on the gas/liquid contact time, and there are two series. The difference in changes found in the tests clearly indicates a catalytic effect.

Real-”L 2 cases-JE Synergistic effect of ozone Continuous tests were conducted using the apparatus shown in Figure 2.

The ozone source has the following characteristics: UV lamp 2.5 Watts, oxygen 10I! ,/Time It has a production of 1 mg/1 per lamp (h) per supply during the period.

The total gas flow rate is 25j2 per hour and the contact time is 19 seconds.

As a comparison, this table shows two samples taken from the previous table conducted in the absence of ozone. Significant test results are also shown.

In the optimal case, 0.582 mmol of manganese produces 3.84 mmol of S. O□ is oxidized in the absence of ozone and with an efficiency of 59%, manganese 0.620 In mmol, 12.87 mmol of SO□ was converted, and the efficiency was 99%. , 12.87 mmol of SO□ conversion or 99% efficiency with 1 ozone in the oxidizer ．． It was found that this could be achieved by introducing 66 mmol/hour (80 ■). Ta. These results demonstrate that SO□ caused by oxygen in the presence of electrochemically activated The catalytic effect of ozone on the oxidation of and ozone and Mii.

It shows the synergistic effect between

The second series of tests contained only 0.620 mmol/ρ manganese. The collected EXn is recycled several times and the oxidation is always the same amount of 502 (13 mmol/e·hr) and variable amounts of ozone.

The total gas flow rate is always 25 ff per hour and the contact time is approximately 19 seconds.

The results obtained are shown in Table ①.

*The amount of purification decreases continuously to less than 40 μ/hour of ozone. At a certain efficiency in oxygen The preferred amount of ozone is 40 to 80 μ/hour. Reading the results and purification rate It can be seen that it is stable for a long time and reaches 99%.

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Claims (9)

[Claims] 1. Gaseous emissions containing sulfur dioxide are converted into enzymes and catalysts based on manganese salts. gaseous effluent containing sulfur dioxide consisting of contacting with a sulfuric acid solution in the presence of a system In the purification treatment method, the catalytic oxidation of sulfur dioxide by enzymes 2 of the gaseous effluent to be purified and containing the catalyst system produced in the electrooxidation of 2. The catalyst system is pre-treated in a concentrated sulfuric acid medium in an amount selected depending on the oxidized sulfur content. gaseous exhaust containing sulfur dioxide, characterized in that it is carried out in a filled oxidation zone; Method for purifying raw materials. 2. Claims in which catalytic oxidation of gaseous effluent containing sulfur dioxide is carried out under oxygen pressure The method for purifying gaseous waste containing sulfur dioxide according to any one of paragraphs 1 to 1. . 3. Catalytic oxidation of gaseous effluents containing sulfur dioxide with small amounts of oxygen carried by oxygen. Sulfur dioxide according to any one of claims 1 to 2, which is carried out in the presence of chlorine. A method for purifying yellow-containing gaseous waste. 4. The purification process comprises at least one of the group consisting of a sulfuric acid medium, a catalyst and recycling of oxygen. According to any one of claims 1 to 3, which is carried out while performing one recirculation. A method for purifying gaseous waste containing sulfur dioxide. 5. Catalytic oxidation of sulfur dioxide-containing gaseous effluents in one or more consecutive oxidations Sulfur dioxide according to any one of claims 1 to 4, which is carried out continuously in a zone. A method for purifying yellow-containing gaseous waste. 6. Catalytic oxidation of gaseous effluents containing sulfur dioxide is carried out in a catalyst system between several oxidation zones. Claims 1 to 5 are carried out successively in several oxidation zones with intermittent introduction. A method for purifying a gaseous waste containing sulfur dioxide according to any one of the above. 7. Any one of claims 1 to 6, characterized in that ozone is introduced intermediately. An apparatus for purifying and treating gaseous effluent containing sulfur dioxide as described above. 8. Two oxidation towers (4a) and (4b) transporting sulfuric acid containing catalyst Mnn+ A tube (8) feeding the ozone-enzyme gas stream to the tube (3), a sulfuric acid recirculation circuit (10) and Claims 1 to 7 further include an intermediate introduction passage (3') for a catalyst system and a catalyst system. waste purification treatment equipment. 9. an oxygen circulation circuit (8) further comprising a scrubber (12) and a recompressor (13); Sulfuric acid circulation circuit (10), circuit for recirculating the catalyst to the electrolyzer (2) (11) and a circuit (14) for recycling the sulfuric acid to the scrubber (12). The method for purifying waste according to claim 10.