DE2119716A1 - Process for the separation of sulfur trioxide from industrial waste gases - Google Patents

Description

SHELL INTERNATIONAL RESEARCH MAATSCHAPPIJ N, V.,

The Hague / Netherlands

Priority: April 24th 1970 / Netherlands / Registration no. 7005974

Process for the separation of sulfur trioxide from industrial waste gases

The present invention relates to a process for the separation of sulfur trioxide from sulfur oxides Industrial exhaust using a solid acceptor.

Industrial waste gases that contain sulfur oxides include waste gases from numerous industrial plants, for example Exhaust gases from ore roasting furnace and from ore melting plants that Exhaust gases from chemical plants and refineries and the exhaust gases

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from sulfuric acid plants and plants in which hydrogen sulfide into elemental sulfur through partial combustion with oxygen or an oxygen-containing gas converted by the process known as the Claus process will. All of these exhaust gases contain sulfur oxides in one larger or smaller extent and can also be finely divided Contain solids such as soot and metal oxides, which are called plugashes. Depending on your - "- origin the industrial exhaust gases mainly contain sulfur dioxide or: Sulfur trioxide as the sulfur oxide. Generally, however also small amounts of sulfur trioxide in the sulfur dioxide-containing Exhaust gases present.

Related to the problem of air pollution it is undesirable that industrial exhaust gases, the sulfur oxides released directly into the atmosphere. To rid these exhaust gases of sulfur oxides were in the Numerous processes for exhaust gas treatment have been proposed in the literature. Some of these procedures are already being scaled up investigated by experimental plants.- The predominant "part of this process is, however, on the separation of sulfur dioxide directed from exhaust gases. Particularly in the process of separating sulfur dioxide via a wet process the presence of minor amounts of sulfur trioxide often a disadvantage.

A method has already been proposed according to what sulfur dioxide from gas mixtures, the sulfur dioxide and contain oxygen, using

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solid acceptors is separated by adding these gas mixtures successively through a first zone in which the fume dioxide to sulfur trioxide by means of an oxidation catalyst is oxidized, and passed through a second zone in which the sulfur trioxide formed on the said solid acceptor is bound, and then the acceptor laden with sulfur trioxide is rained. at In such a process, a sulfur trioxide contained in the exhaust gas is also retained by the acceptor used will.

A disadvantage of the method described above can be seen in the fact that the acceptors used consist of a solid support, for example aluminum oxide, on which a metal and / or a "metal compound" is applied became. However, the use of metal-containing acceptors makes this sulfur dioxide removal process relative expensive, while the loaded acceptors with a reducing Gas, for example a gas mixture containing hydrogen gas or light hydrocarbons, can be regenerated must, which also leads to an increase in the cost of the procedure.

An object of the present invention is to provide a process for the separation of sulfur trioxide, in particular from industrial emissions. Another goal lies in the use of solid acceptors in these processes that are essentially free of metals and / or deposited thereon Metal compounds are. Another goal is creation

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a process that enables the loaded acceptor to be regenerated economically.

The invention therefore relates to a process for separating sulfur trioxide from sulfur oxides Industrial exhaust gases using a solid acceptor, according to which process industrial exhaust gases, the Schwofel trioxide contain, brought into contact with a solid acceptor at elevated temperature, which in its entirety or substantially consists of an inorganic oxide, and the said acceptor means after loading with sulfur trioxide Containing hydrogen sulfide or a hydrogen sulfide Gas is regenerated, after which the regenerated acceptor v / .K'd'-r rn, i1; dori DchwofoJ-fcrioxyd cn thai tendon exhaust in contact brought v / ird.

The process according to the invention can suitably be used for the separation of sulfur trioxide from exhaust gases, originating from plants that produce hot acid or further processing. When such gases are released into the atmosphere, condensation can result in the formation of a mist which is visible as a white 'A' wolf. Such a Fog is very persistent and difficult to control, and besides being inherently corrosive, it is also harmful to health. The method according to the invention enables it now, this colony formation through acceptance of the to avoid last amounts of sulfur trioxide. That said However, the method is also suitable for the treatment of industrial exhaust gases that contain sulfur dioxide. To this end, you want

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the exhaust gases mentioned initially with an acidic oil-containing one Gas or gas mixture, "for example air, in the presence of a Oxidation catalyst treated v / ground before after Method according to the invention can be treated further.

Any oxide which can bind sulfur trioxide and which regenerates to the oxide after binding the last-mentioned compound with hydrogen sulphide or a gas containing hydrogen sulphide can be used as a solid acceptor, which consists entirely or essentially of an inorganic oxide A solid acceptor particularly suitable for this purpose is activated alumina, for example tv \ -, α- or γ-alurainium oxide. Other suitable acceptors are magnesia or alumina, or impregnated on an inert carrier of, for example, silicon dioxide-aluminum oxide. Magnesia. It is also possible to use mixtures of two or more of the acceptors mentioned.

The solid acceptors which are used in the process according to the invention to absorb the sulfur trioxide from industrial waste gases are free or essentially free of metals and / or metal compounds which are usually deposited on acceptors of the type mentioned above as carriers for this special purpose. However, the acceptors used need not be completely pure and may · in the acceptor other Ke τ be allverbindungen as impurities So beispielsv / else known that the commercial aluminas Siliziuindioxyd, iron (III) oxide and titanium dioxide in! 'Narrow below 0 , Contain 1% by weight, while .sodium oxide in an amount of less than 1% by weight? » is present.

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The solid acceptors according to the invention can Alkali metal oxides and / or - ^ rdalkaiimetalloxyde in larger: Quantities included. In this case, these are the oxides mentioned preferably contained in an amount of less than 10% by weight.

According to the invention is loaded with sulfur trioxide solid acceptor with hydrogen sulfide or hydrogen sulfide containing gases regenerated. As hydrogen sulfide containing gases may suitably be used gases such as 10 or more vol%, preferably more contain more than 25% by volume of hydrogen sulfide. Such gases are available in large quantities in refineries.

The process according to the invention can be carried out within a wide temperature range. In order to prevent the condensation of sulfur trioxide and the subsequent formation of a white cloud, the temperature should in any case be above 180 ° C. A very suitable temperature range extends from 250 to 625 ° C. This temperature range also includes the final temperatures of numerous industrial waste gases, for example waste gases or fire gases, when they are fed into the chimney. This is an advantage that is clearly evident to any person skilled in the art, because such gases then lose only a little of their buoyancy while they are being treated according to the method according to the invention. It v / ill be preferred to employ temperatures between 350 and 4-5O ⁰ C.

The subsequent regeneration of the loaded solid acceptor is preferably carried out at the same temperature carried out as the previous loading. 'If that too

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is by no means strictly / conditionally necessary , then the P.Ggenerationsteir.peraturur is different. not r.ehr than 5O ⁰ C from the loading temperature, ix easy Verfahrensfährung be guaranteed. In general, the regeneration temperature is between 200 and 550 ° C., and in particular between 280 and C.

The space velocities maintained during loading are advantageously between 100 and 50,000 λ ^τ 1 gas per 1 acceptor and hour, while the room velocities used during regeneration are between 5 and 3,000 Ni gas / l acceptor and hour ".

As already mentioned, the method according to the invention can can also be applied to exhaust gases containing sulfur dioxide. The invention thus also relates to a method for cleaning industrial waste gases which contain sulfur compounds, according to which process the sulfur compounds in .diesen gases initially to sulfur trioxide with oxygen or an oxygen-containing gas in the presence of an oxidation catalyst and then the sulfur trioxide is separated from said exhaust gases by loading a solid acceptor.

■ Oxidation catalysts suitable for this purpose are described in detail in the literature and are capable of well known in the art. To cite just one example, reference is made to a catalyst which consists of a Vanadium compound and a potassium compound consists of the on a solid (carrier, for example silicon dioxide, are applied.

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The oxidation of sulfur compounds, for example of sulfur dioxide, in the exhaust gases mentioned is preferred made in the same temperature range that is used for loading is complied with. This has the distribution that the industrial exhaust gases, such as fire gases, one after the other are oxidized and freed from sulfur trioxide without adversely affecting the heat balance, so that these exhaust gases can be fed directly to the chimney after additional heat extraction or even without such. The oxygen-containing gas can advantageously be air or oxygen-enriched air can be used.

To ensure that no sulfur oxides, be it in the form of sulfur dioxide or of sulfur trioxide or of Both of them get into the atmosphere not even in small amounts, "is further proposed, after the sulfur trioxide loading stage to provide a safety bed made of a sulfur oxide acceptor. A suitable acceptor for this particular one The purpose is an acceptor, which consists of a solid support on which a * metal and / or metal! has been brought. A particularly suitable acceptor consists of copper and / or copper oxide on alumina. Any sulfur dioxide, which was not converted into sulfur trioxide in the oxidation stage, and any sulfur trioxide that was released by the solid acceptor for sulfur trioxide was not taken up, is then taken up by the acceptor made of copper and / or copper oxide Clay can be absorbed. Because the majority of the sulfur oxides have already been converted in the previous process stages and has been included, represents the use of a ^

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and / or acceptor containing metal compounds in the form a safety bed only represents a small proportion of the total costs for the entire procedure.

Industrial fumes, such as fire gases, contain generally a large proportion of solids such as ash and soot. To prevent the fixed beds of the oxidation catalyst and / or acceptor are clogged after short periods, the oxidation stage and the Loading stage for gases containing such solids is preferred executed in specially designed devices. A device preferred for this purpose has at least largely parallel gas channels, which are limited by permeable walls, behind which the acceptor or the oxidation catalyst is arranged, which acceptor or oxidation catalyst for the gas and its components is freely accessible, but not for the solid particles such as soot and fly ash. The gas channels are thereby at all not or significantly less rapidly clogged by the solid particles present, so that such devices do a lot can be in operation for longer. For the oxidation stage As a rule, one device of this type will suffice, while two devices of this type are preferred for loading uses v / ground to allow switching to the other device when the solid acceptor is in first apparatus must be regenerated.

The oxidation catalyst and / or solid acceptor can be used in any form. You can, for example,

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can also be used as shaped particles containing 0.1 to 10 mn, for example 0.5 to 5 raa> are tall, or in shape of panels with larger dimensions, e.g. 10 χ 10 approx or larger with a thickness of 0.5 to 5 cm. The latter In this case, industrial emissions can be detrimental also, be treated in an apparatus in which the at least largely parallel gas channels formed from the plate-shaped Oxydationskatalyaator or acceptor itself and are limited. If desired, the molded panels but can also be arranged between gas-permeable walls, | which for example consist of wire mesh. '

It will be clear to the person skilled in the art that the above-mentioned devices are also used in combination can. For example, a device that has at least largely parallel gas channels that are permeable from Walls for the oxidation catalyst are limited, well rather Oxidation catalyst in this case is in the form of shaped particles, combined with a device in which the at least largely parallel gas channels from the plate-shaped acceptor for the solids themselves are educated and limited.

For the production of mechanically resistant acceptor plates that last for a long time without becoming hot or disintegrated can be used, the following procedure can be used will:

The oxidic acceptor material must first be heated to a temperature above which no or essentially ■ lent no more shrinkage occurs, be freed from V / ater bo.

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For clay this temperature is above -80 ° C, so that this acceptor material or a thermic dehydrate is preferably between. 600 and 1100 ⁰ C is calcined. The calcined acceptor material is then mixed with a binding agent, optionally with the addition of water, and the mixture of acceptor material and binding agent is pressed into sheets of the desired dimensions. The molded Akzeptorplatten subsequently, if desired, before being carried out by drying at temperatures up to 200 ° C can v / ground to temperatures of over 780 ° C, preferably heated from 800 to 150o C ^0. After cooling, the acceptor plates are suitable for the use described above.

Suitable binders include clays, for example kaolinite, attapulgite, bentonite, halloysite and ivontmorillonite. Kaolinite or kaolin is preferred because it is easily cleaned and crushed to a particle size suitable for mixing can be.

However, the amount of binding agent to be used depends on to a certain extent on the type of binder used and the acceptor material used, but this can be in each special pail by means of a trial package of Acceptor plates can be easily determined. In the case of clay and alumina, it is preferred to be 0.1 to 0.5 parts by weight Use clay per unit of aluminum oxide.

around. Acceptor plates, of particular mechanical strength to obtain, some of the binder intended for use through glass in the form of finely divided

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Glass, for example glass powder or glass frit, replaces ground. It is preferred that the strength of the clay binder, which is to be replaced by finely divided glass or glass frit, is dimensioned such that the acceptor plates to be heated are less than 10% by weight, preferably 2 to 6% by weight. -% glass, based on. Dry substance. Suitable types of glass are soda lime glass, lead glass, silicate glass and the like.

The acceptor plates obtained by the method described above are already slightly porous. In order to increase their porosity, however, it is preferred to add a pore former to the mixture of calcined acceptor material and binding agent. Flammable materials can be used as pore former, for example flour, wood chips, synthetic or natural resins, paraffin wax, sugar or gas-forming salts such as persalts or peroxides, can be added. A pore-forming agent is preferably used which is completely converted into one or more gaseous compounds, so that no impurities remain in the finished acceptor. Polypivalolactone and especially polypropylene are suitable for this purpose. The pore-formers may be of 5, based on the total amount of acceptor and binder amount used to 15 wt? "In a narrow · ^ia from 1 to 25 wt .-%, preferably.

Although the process has been described with specific reference to an acceptor in the form of plates, so it is clear that the process described for the production of mechanically stable acceptor is autfh for production by differently shaped acceptors, for example in the form of extrudates, tablets, pills, spheres and the like can be.

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For the separation of sulfur compounds from industrial exhaust gases, which do not contain solid dust particles can be solid beds of oxidation catalyst and / or solid acceptor be used. Compared to the devices discussed above, a fixed bed has the advantages that the reactor can be smaller and of simpler construction, and that the acceptor to a greater extent with sulfur trioxide can be loaded. These advantages generally outweigh the disadvantages of a higher pressure loss the fixed bed and the risk of greater disintegration of the acceptor particles. Fixed beds can be used for example the processing of the exhaust gases from the Claus process used v / ground. Such gases containing approximately 1% by volume of hydrogen sulfide and 0.5% by volume of sulfur dioxide may suitably by the process according to the invention from the sulfur compounds mentioned be freed by first oxidizing them to sulfur trioxide, as described above, and then the sulfur trioxide formed is dumped on the solid acceptor.

In general, the removal of fire gases and Claus exhaust gases in an oil refinery is a serious problem. In this case, it can be advantageous to treat the two gases together in a device which is provided with at least largely parallel gas channels in the manner described , in which the combined exhaust gases are first oxidized and then freed from sulfur trioxide. On the other hand, the exhaust gases can also come out

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Sulfuric acid production plants or processing. "insoles in the combine "con Abf; ar, c nnch der Gxydn.tionsr; ti * fe, However was initiated before a charge stage.

The method according to the invention is used in the following Examples and with reference to the? Ig. 1 to 4 of the attached drawing explained in more detail.

Example 1: "This example illustrates a solid acceptor of the type described in this application" Kind of a higher load of sulfur oxides under identical Test conditions are taken up by air »one described in the literature Acceptor consisting of a copper compound ai — Γ a solid Carrier exists.

As a starting material for the production of a gas that

Contains sulfur trioxide, a gas mixture was used which consisted of 1.4% by volume of sulfur dioxide in air. This gas mixture was schwindigke through a fixed bed with a Gxydationskatalysator Rauinge it passed 500 Nl gas / l of catalyst per hour .. The oxidation catalyst consisted of a Siliziumdioxydträger to which 7 wt -.% VpOj- and 8 parts by weight yS KO (based on the carrier) was applied} this catalyst was used in the form of particles with a size between 1 and $ mn. The temperature in the bed was 425 ° C. Analysis of the gas mixture leaving the catalyst bed indicated that an essentially quantitative conversion to sulfur trioxide had occurred.

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DR. VOLK P. VOSSIUI DR. TO

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The formed gas containing sulfur trioxide was

mil; Stickritoff dilutes up the pre-diluted gas of the. desired Sulfur trioxide content expressed in parts per million by volume (ppmv). This gas was determined by an experimental arrangement which is a cylindrical tube of wire mesh (0.5 ksi Mesh size) and lined with γ.-AlpO as an acceptor was. The alumina had a particle size of 0.5 to 1 mm and was in a layer thickness of 2 mm over plotted the total length of this pipe. The cylindrical tube had a length of 150 cm and an inside diameter from 10 mn.

A number of experiments have been carried out, whereby different sulfur trioxide contents of the gas and different Loading temperatures have been observed. After each series of tests the loaded aluminum oxide became with 100% hydrogen sulfide regenerated, after which the regenerated Aluniniur: - oxide was reloaded. The regeneration was carried out at various Temperatures made.

The comparison test with a known Cu / AlpO ^ - acceptor for sulfur dioxide was carried out in the same way, in the test arrangement described above. For this purpose, the cylindrical tube was lined with a 2 mm thick layer of the Cu / AlpO., Acceptor, with particles from 0.5 to 1 mm in size being used. The composition of this known acceptor was 9 parts by weight of copper to 100 parts by weight:% γ-AIgO ₇ . In the latter case, the regeneration was carried out with a nitrogen / hydrogen gas mixture with 50 vol .- / 'ITp. ■ '.

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H,

The expiry dates for the various test series are listed in Table A below. The results obtained are shown in Table B. In order to enable a comparison of these results with those of the comparative experiment, the loadings of the acceptor according to the invention were _{calculated as% by weight SO 0} , based on fresh or regenerated acceptor. The fourths listed in Table B were obtained by determining after each test the total amount of sulfur trioxide or sulfur dioxide which had escaped from the pipe, as well as the corresponding loading of the acceptor at this sulfur anoxide concentration.

Tabel

Procedural conditions Ve
1 . rsuchsi
2 'one
3 4th 5 Comparative
attempt Rough speed of the
sulfur oxide-containing gas,
NlA Zh 8800 8800 8800 8800 8800 8800 Loading temperature ^{, 0 C} 250 250 500 425 425 SO ^ concentration, ppmv
Regeneration gas 2200
H ₂ S 2700 1800 * 1800 150 0.14 vol
% so ₂
(50-50%) Room velocity of the
Regeneration gas, NlZlZl ¹ ■ '250 250 25O 25O 25O 330 Regeneration temperature ^{, 0 C} 425 250 25O 500 425 425

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Table B.

Attempt
line - 2 Acceptor charge,
calculated as SO ₉ ,
Gev /.-%. Gesasitabstron, calculated
in Gev /.- vi, based on
supplied SO ₂ ; or SOp 1 0.1 21st 3 0.8 22nd 2.0 25th 4th 5.8 35 '5 5.8 40 Comparative
attempt 9.5 40, 7.7 26th 11 31.5 9 45. 1.4 16 0
1.3 43
45 2.0 46 3.0 47

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The results given in the table clearly show that an essentially motall-free acceptor, for example γ-Αΐ ^ Ο ;? » takes up a higher SO ^ loading than a metal-containing acceptor, for example Cu / Al ^ O, for SO ₀ . With regard to the effectiveness of the separation of sulfur oxides from exhaust gases, the experiments described do not allow any conclusion that the pipe length used is too short. The use of apparatus with a height or gas duct length of at least 6 m, on the other hand, has the effect that the sulfur oxides are quantitatively separated off. From the values obtained in test series 1 to 4, however, it can be concluded that the regeneration of the loaded acceptors was practically 100%, because in the case of an incomplete regeneration the total waste would have shown considerable differences with the same or approximately the same loading.

Example 2: A fire gas is freed from sulfur dioxide by adding sufficient kit air in the presence of an oxidation catalyst is oxidized and then passed through an acceptor, which according to your inventive method is used. For this purpose, the furnace gas, as shown in more detail in Fig.4-, after passing through the Convection zone 22 of the furnace 20 by a furnace gas cleaning system conducted from a Cxydationsvorrichtung 24, as shown in Figures 1 and 2, and a subsequent one Loading device 25, v / ie shown in Figo, consists of the devices in the exhaust duct 25,

which leads to the chimney 26 are provided.

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The 3? 1 ze I et a device for the oxidation of Sulfur dioxide to sulfur trioxide. There are with the reference numerals 1 denotes open gas channels that are parallel to each other run and are separated from one another by catalyst chambers 2 which are filled with catalyst particles 3. The gas channels 1 are provided with a gas-permeable V / and in the form of a fine-meshed network 4-. The gas ducts and catalyst chambers are formed by means of frames 10, to which the net is attached, which frames form a unit using spacers 7a, 7b, 7c and 7d are connected. The entire arrangement is provided by one or more screw spindles 8 with hats 9 are held together. The catalyst chambers are at the Top left open to be filled with the catalyst to be able to; the gas chambers are on the top as well as on the bottom by means of the spacers 7a, 7b and 7d closed, which extend in the longitudinal direction of the frame stretch. The catalyst chambers are through at the bottom Spacers 7c »which extend in a longitudinal direction, locked. The entire arrangement is arranged within the smoke exhaust duct 5, which also has several such units may contain. In the case shown, there is the Raxich gas duct from a fixed piece 5a and a removable piece 5b to introduce or replace one or more units to enable.

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The Pig. 2 be a side arm ic hi; des Eahr.ens IG. ^{FIG. 1} shows a cross section of an arrangement of such frames along the line AA 1. The network 4, which can be welded to the frame 10, is held in the desired position by means of horizontally and vertically arranged rods 6 and 6a and prevented from discarding.

The Fig.5a and Jb shows a device for recording of SO · ,, being the acceptor used in the form of shaped Plates present. The arrangement of the acceptor plates 12 is also introduced into the breath gas channel 5. The reference signs 1J and 14 denote a gas inlet and gas outlet, respectively, -die "above the gas channels 18, which are delimited by the acceptor plates 12, are related to each other. The plate arrangement is supported by support elements 15 and spacers 16 at the desired Place held and supported. The acceptor plates 12 are arranged one on top of the other or through a small gap 17 separated. The acceptor plates consist of 20x20x0.5 cn large pieces of γ-AlpCU. '

FIG. 5b shows a cross-section of FIG. 5a along the line AA '. In the drawing, the wall 5 is interrupted to indicate that the total number of plates is in one: smoke gas duct or the like., Albeit in FIG. 5a an arrangement of 5 acceptor plates over the width of the flue gas channel is illustrated, is actually determined by the width of the channel _5, the thickness of the acceptor pieces used and the width of the gas channels delimited by these pieces. The flue gas, which is freed from sulfur oxides in this way, has the following composition:

- 20 1 0 9 8 A ^{6/1 2 7 3 BAD 0R {GI} * AL

74 , 5 VoI of. CO ₂ 13th , 6 Jl Il E ₂ O 9 , 0 ti Il O ₂ 2 , 7 Il ! I SO ₂ O , 2 Il ti SO-, O , 002 U If

as well as soot and fly ash in a conventional V, ^r ice.

This flue gas is ^{oxidized at 430 °} C. by means of an oxidation catalyst of the same composition as indicated in Example 1. For this cylinder, it is passed through the described oxidation device 24 at a roughing rate of 5000 Nl / 1 catalyst and hour. The flue gas emerging from this device is then fed to the loading device 25. The SO., At 420 ^° C., is taken up in this device.

The materials used for the apparatus 24 dimensions (about 7.5 long, 3 m high and Jm wide) and for the device 25 (approximately 9 ^ la ^ E "^ 3. High and 3m wide) the γ-AIPO ^ has a Regenerate with 100% hydrogen sulphide approximately every two hours for an hour. The regeneration .If "at the same temperature of approximately 420 ⁰ C made. The regeneration gas consists of a mixture of sulfur dioxide, hydrogen sulphide and sulfur vapor, and a Claus plant is supplied.

To enable a continuous separation of sulfur dioxide from the flue gas, two acceptor devices are used, which alternate in the acceptance

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and regeneration phfice bof ir · »-; on. These two criminals . you can dip next to each other in the? .auch ~ ankanal engerdne-t; wercler ,, whereby each performance mi / j is provided with the corresponding r.:lr- Vent;:! lon supplied and discharge lines for the regeneration gas.

Example 3 ' The acceptor plates suitable for use in a device according to Example 2 can be used. can be obtained in the following way:

80 parts by weight of γ-Α1ρΟ ₇ , which was obtained by spray drying and has a water content of 23% by weight and a particle size of about -3 ° C / U, are placed in an oven in which the temperature is uniform is increased from room temperature to 850 ⁰ C in a period of 200 Llinuton. Alumina v / ith then for three hours at 85O ⁰ C sintered. The sintered Alpo is cooled to skin temperature outside the furnace and then 250 parts by volume of water are added. To the wetted aluminum oxide, 22 parts by weight of kaolin are added, which is colloidally suspended in 22 parts by weight of water (particle size of the kaolin less than 2 Ai) . The suspension of Aluminiunoxyd in clay is filtered and dried at 100 ⁰ C •. The dried mixture now contains about 71 % water, based on dry matter. This mixture is mixed with 10% by weight, based on dry substance, of a pore-forming agent, for which purpose polypropylene can suitably be used. After the above-mentioned pore-forming agent has been incorporated, the total mixture is formed in a manner known per se with the formation of shaped bodies:

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Compacted to the desired dimensions. The shaped pieces or bricks are then in a. Furnace evenly from room temperature over 200 "inutes at 850 ⁰ C. and then for 2 hours lan · - in this" fired temperature. The oven temperature is then gradually lowered to room temperature over a period of 4 hours. The cooled bricks are suitable for immediate use »

Example 4-: In an experimental arrangement, which had an oxidation device and a loading device as well as an incinerator and the necessary supply lines and ivnsc ^ üvrse for the supply of air, nitrogen, sulfur dioxide and hydrogen sulfide, the mechanical stability of γ-aluminum oxide as an acceptor for the method according to the invention is determined. For this purpose, 1.65 NlA SO _{2 were} added with 10 KlA nitrogen and 93 KlA LuTt via an oxidation catalyst (VoO ^ / KpO / SiOp) at a

Temperature of 40O to 450 ⁰ C passed. The sulfur dioxide was essentially completely oxidized to SO. The exhaust gas from the oxidation device was diluted with 100 ITlA air and then passed at ^ 25 ° C over the γ-ΑΙρΟ, -acceptor present in the loading device. After dilution with air, the gas mixture contained 0.15 "oil - ;:" ZO ₇ as well as traces of SOp. The space velocity was 9000 Wl gas mixture / l acceptor / h. (9000 ITl ~ ¹ h ~ ¹ ).

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The loading device consisted of a 4-0 cm long and 4 cm in diameter quartz reactor with 100 ml of γ-AIpO was filled. The firm bed was reddened of 8 cm and the rest of the reactor was occupied by a heating device.

The exhaust gas from the loading device was analyzed _{for SO 7} and SO _2. No breakthrough was found after a continuous loading time of 30 minutes. The loading of the acceptor after this JO minute period was 5.4 g SO / 100 g acceptor.

After loading, the test was carried out with Purged with nitrogen to avoid analytical errors.

The loaded γ-ΑΙρΟ, -acceptor was with 10 Nl / h H ^ S, which was diluted with 10 Nl / h Np, regenerated. This gas mixture, containing hydrogen sulfide, was at a temperature of 425 ° C and with a space velocity of —1 —1

200 Nl.1 .h passed directly through the acceptor. The regeneration exhaust gas, water, sulfur and sulfur dioxide contained in addition to nitrogen, was diluted h of air with 400 Nl / and burned in the furnace at 600 ⁰ C. The total amount of SOp formed was determined in the combustion mixture. It was found that the acceptor could be completely regenerated within 20 minutes.

. After regeneration, the ventilation device was started with Air purged to remove any sulfur that may have condensed in the lines.

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Vf

211971S

After 524 cycles of loading and regeneration, the experiment was ended. At this point in time, 22.5 S SO ₇ / g acceptor had been separated off. The acceptor bed was separated into an upper layer and a lower layer and the acceptor was checked for compressive strength, pore volume and specific surface area The results obtained are shown in Table C.

Table C:

Acceptor - New after SP4 ZvkÜen Lower class *
Compressive strength kg / cnr 5.3 upper layer* 5.0 Pore volume, ml / g 0.61 5.0 0.58 specific surface 0.58 ni ² / g 29A 208.7 185

* SO and HpS are in the top layer of the bed initiated.

From the above data it can be seen that the. Acceptor is mechanically stable. "

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The present invention is also useful for use in a process in which. first of all, fume dioxide separated from industrial waste gases by means of a solid acceptor suitable for this purpose and at which Then process the sulfur trioxide that was already present in these exhaust gases and / or ir.it during the loading Sulfur dioxide was optionally formed, after a Method according to the invention unloaded on an acceptor will. One such process, in the first place - sulfur dioxide and then sulfur trioxide is absorbed, is particularly suitable for use in cases where the sulfur trioxide content in the chimney gases is in the In connection with the cloud formation already mentioned, it must be kept below a low value, must be grounded.

The chimney gases generally contain a fixed percentage of sulfur trioxide, based on the total amount of sulfur oxides present. For example, if Copper and / or copper oxide on aluminum oxide is used as an acceptor for sulfur oxides, it is increasing Breakthrough of sulfur trioxide especially towards the end the loading occur, v / eil the acceptor is almost completely loaded. In this case it is particularly favorable a safety bed made of aluminum oxide ■ or magnesia to collect the sulfur trioxide. Such a bed can be used for a long time and only needs occasionally with hydrogen sulfide or a gas containing hydrogen sulphide be regenerated.

- 26 10 9846 / 1,273

Claims (1)

Claims Ί. Process for the separation of Schwofeltrioxyd from Industrial waste gases containing sulfur oxides using a solid acceptor, characterized in that sulfur trioxide containing industrial exhaust gases at elevated temperatures be brought into contact with a solid acceptor, the consists entirely or essentially of an inorganic oxide and that said acceptor is loaded with Sulfur trioxide with hydrogen sulfide or a hydrogen sulfide containing gas is regenerated, after which the regenerated acceptor again with the sulfur trioxide containing Exhaust gases is brought into contact. 2. The method according to claim 1, characterized by that activated alumina as a solid acceptor consisting entirely or essentially of an inorganic oxide, Magnesia or mixtures thereof are used. 3. Procedure according to. Claim 2, characterized in that that the acceptor consists of clay or magnesia, which are impregnated on an inert carrier. 4-. Method according to one of Claims 1 to 3, characterized characterized in that the solid acceptor is alkali metal oxides or alkaline earth metal oxides, preferably in an amount of less than 10% by weight, based on the solid acceptor, contains. . BATH ORIGINAL - 27- 109 846/1273 5 »Method according to one of claims 1 to 4-, characterized characterized in that the gas containing hydrogen sulphide has 10 or more vol .-%, preferably more than 25 vol .-% hydrogen sulphide contains. 6. The method according to any one of claims 1 "to 5» thereby characterized in that the exhaust gases containing sulfur trioxide with the solid acceptor at a temperature of 250 to 625 C brought into contact. 7 »'Method according to claim 6, characterized in that that the temperature between 350 and 4-50 C is kept. 8. The method according to any one of claims 1 to 7 »characterized in that the regeneration at a temperature is carried out by no more than 50 ° C from the loading temperature is different. 9 · The method according to claim 8, characterized in that the regeneration between 200 and 625 ° C, preferably between 280 and 4-75 ° C. 10. The method according to any one of claims 1 to 9> characterized in that the exhaust gases containing sulfur trioxide brought into contact with the acceptor at a space velocity of 100 to JO -000 Nl gas / l acceptor / h. 11. The method according to any one of claims 1 to 10, characterized in that the regeneration at a space velocity of hydrogen sulfide or gas containing hydrogen sulfide from 5 to 3000 ITl gas / l acceptor / h will. - 28 - 10 9 8 4 6/1273 12. The method according to any one of claims 1 to 11, characterized in that the acceptor used in the form of shaped acceptor plates or bricks. IJ. A method according to claim 12, characterized in that panels or brick ^ -AlpO., Are used, the by calcining alumina or alumina hydrate above 780 ⁰ C, mixing the calcined material with a binder, optionally with addition of water, compacting Mixture of acceptor material and binder under pressure to form plates or bricks with the desired dimensions and heating of the resulting plates or bricks to temperatures of over 780 ° C., optionally after previous drying at temperatures of up to 200 ^° C., have been obtained. 14. The method according to claim 13, characterized in that aluminum oxide or alumina hydrate, which has been freed from water ^{by heating to a temperature between 800 and 1100 ° C., is used as the acceptor material.} 15. The method according to claim 13 or 14, characterized in that shaped plates or bricks are used which have been heated ^{to a "temperature of 800 to 1300 0 C."} 16. The method according to any one of claims 13 to 15 * characterized in that a clay is used as a binder. - 29 - 109846/1273 17 · Method according to one of Claims 14 to 16, characterized characterized in that the clay in an amount of 0.1 to 0.5 Parts by weight of clay per part by weight of clay is used. l8. Method according to claim 14 or 15 *, characterized in that that part of the binder is replaced by finely divided GIaG will. 19 · The method of claim 18, characterized in that the plates to be heated or brick f less than 10 weight percent, preferably 2 to 6 weight percent, based on dry substance, contained in glass. 20. The method according to claim l8 and 19 »characterized in that that a soda-lime glass is used as the glass. 21. The method according to any one of claims 1 j5 to 20, characterized characterized in that a pore former is added to the mixture of acceptor material and binder. 22. The method according to claim 21, characterized in that the pore former in an amount of 1 to 25 percent by weight, preferably from 5 to 15 percent by weight, based on acceptor material and binders. - 30 - BATH ORIGINAL 109846/1273 2j5. Method according to one of Claims 21 and 22, characterized characterized in that polypropylene or poly pivalolactone is used as the pore formation is used. 24. The method according to claim 1 for cleaning industrial exhaust gases, which contain sulfur compounds other than sulfur trioxide, characterized in that the sulfur compounds in these exhaust gases are first oxidized to sulfur trioxide with oxygen or an oxygen-containing gas in the presence of an oxidation catalyst and this sulfur trioxide is then separated by loading a solid acceptor, which is wholly or essentially composed of an inorganic Oxide exists. 25. The method according to claim 24, characterized in that the oxidation in the same temperature range as that of the load is performed. 26. The method according to claim 24 or 25 »characterized in that that a furnace gas or a tail gas from a Claus plant is used as industrial waste gas. 27. The method according to any one of claims 1 to 26, characterized in that after passing over the solid acceptor the exhaust gases are additionally brought into contact with a copper and / or copper oxide on alumina acceptor. BATH ORIGINAL 10 9 8 4 6/1273 Blank page