DE1817709A1 - Process for purifying gases - Google Patents

Description

Process for purifying gases The invention requires a method for some full cooking by removing fully z @ er21tlrcini @; unE; en in. pore similar feces :: - honent.cll and tf: ilchellfc @ rmiE; er.schwellstoffe. The invention; Go out in front of the Ailfgcb) a, Iah Verunrui.rIii: ungen, the 1I1 i_T ': it>;: r line f' .. 15 fe :: tE ': Schubstoffe l! orhensen AM Z. t :. as 1'lugaäC (lu or ga i f '() rniEn , in 11 ..: 1e V: I'unr "Ln.iE, unfgen, z . :), F).! If; far away should üabe1 the vei'uare: ni _; lill; 'eI:! let = will. (),!: I ', I, 1: I. i U1; # 1.f1,.; 1: 1 :, C .. dalll r all Who 'eats'> I ?: staL ".,. ... ... in front of J u t 'der7 <:: @@. @.'. ifl @ ;: i ,: all (* .1f :. fL: I.: 1 A E. :. ff.:. .1U _._. 1 ._, .. i.,. Aifr <L1 1f!. @ I ... ha: ..; `:, ei:. l.lfng i 12h #. KAM, Ar ein unzum @.:. Tlff: l; @i. #) I ... :. :. ".. ...,.,. Icke: COw dir 1. (; an 1'II tj;,.,. - ..,,. j.ufpr:. 1 .. . ..i .. ... , .., Gas-liquid at such a speed to the Au; pra: L-- fliche directs that the Aufprallfl @ :. ctte @ion of the L'1it Although wetted, but not durchdrurtf; c> t that tr.tr, d: on. the lienge of the liquid is so good that the in the; 'Li.issiEine it pebble components of gas as well as those contained in gas particulate suspended matter is stirred into the liquid the; and that one finally has the casualness that nJunf; en contains, recovered. Numerous Indü:>ti-ieL; ttse, such as smelting furnace gases, ab; ase full of many chemical hrlla.gen, Flue gases from foal or 11 burning stoves, as they are in elec- tric power plant. are used, exhaust gases from;> sulfur furnaces, as they are used in sulfuric acid plants, usu. in Fra- ge. Often these gases also contain smaller strings solid Schwebstof fen or other Verrar conditions such. B. bchwe-- feltrioxytd. Smoke gases from coal-burning stoves lead to two For example, a part of the filler, which is used as a flight ash is known; This can also be adsorbed sulfur: contain oxide. Antiire:> O2-containing exhaust gases Unnen,.; Enir; Lis t; ar does not contain any solid suspended matter, but stated Amounts of S03. For example, £ ?. the exhaust from 2c;: uefe.Lhrea-- nern that are used when generating f; clt #: ret '@@. 1; 1-_ltr @. ver; ::: n: et Become, zuar rtltti: ti :: ctt 1: ... fitte l '@. s tert 2chwehstot fe, but urcha, lnde Sets Ynn Si,! I; 1.3,. ; Jhnl I l.11 Form vun Nehe L Mur Wi nun Tr5Ftfchen is present. Anduret'teits is t :: i 4_n know 209-- containing output = generated werlnn 1 ": unC: It, .`tte pl, '). i , t, l: icit free v11.50 .; are, the tt) e1 'ff: .-, tt: #: i e: twt: h .. t o. f .. as impurity be included. ;; '_ :: N G u2 unites in A1) are however valid. fit after i: ivl il t '._ .ivn,' ut: an .SO 3 l; rr .'t naen, d..i epi..ta; lei '; e. ,. earth at irr 'J "? L> t annung.: r'1 tr-nn, t, nffen bei. from ". 1, r, .. r The presence of one or both of these additional lichen impurities, tungsten in SO-containing exhaust gases, has the SO2 recovery process described above Difficulties led to the 'profitability of the Ed. = Rh renn heeintrd, chtigen. 5o did that in the Abzas- existing S03 the Neigun @ T, with the one in the absorption solution existing Kaliurnsul.fi.t to react, being potassium sulfate which is generally formed together with the potassium Pyrosulfite crystallizes out -, -, If the separation then occurs is carried out by crystallization. Since the potassium sulphate can be a substance which lowers the partial pressure of the sulfur dioxide and which consumes the potassium sulphite, it is expediently removed from the pyrosulphite crystals at an additional cost before they are heated to give off the SO2, if the full efficiency of the process is to be guaranteed. Although the different solubilities of the sulfate and of the pyrosulfite in water can be used for this purpose, the requirement of an additional separation step leads to a deterioration in the process. As regards the presence of suspended solid particles in the SO 2 -containing exhaust gases which are treated by the above-mentioned process, their presence leads to numerous disadvantages. Z.8. fly ash is a highly erosive material; if not removed, serious erosion problems can arise for the connectors, vessels, etc., of the entire system. Furthermore, it has a tendency to separate itself into the system as a solid nose, which leads to serious congestion problems. Furthermore, as already mentioned, almost all of the SO3 contained in these exhaust gases is adsorbed on the surface of the fly ash particles and there is a risk that it will not be removed from the gases if the ash itself is not removed. Other difficulties arise when there are solid particulate matter in the gases that are sent to the chemical absorption stage, because the particulate matter is caught in the absorption solution and, if not subsequently removed, can easily accumulate, when the absorption solution is regenerated and returned, as a result of which the absorption capacity _defi-rösung for SO2 is slowly and steadily reduced and a disruption in the separation (e.g. by crystallization) of the potassium bisulfite can occur. The solid suspended matter in the SO 2 -containing exhaust gases are often the incombustible components of fossil fuels, which are often referred to as fly ash, as already mentioned above and explained in more detail below.

It has now surprisingly been found that a modification of the above-mentioned SO2 recovery process, in which the exhaust gas stream is sprinkled with water before it is passed into the chemical absorption zone, leads to a simple and effective removal of any solid suspended matter from the gases , whereby a sufficiently low level of solids in the gases is achieved before they are sent to the absorption stage. Another advantage of the pre-sprinkling stage is that small amounts of any sulfur trioxide that may be present in the gases are absorbed by the sprinkling water and are also removed from the gauzes before they are brought into contact with the potassium sulfite absorption solution. As a result of the activation of this pre-sprinkling stage between the exhaust gas source and the chemical absorption zone in the SO2 recovery system, one observes that exhaust gases with a solid suspended matter content of up to about 23 g per .m3 of gas or more (10 grains / cu.ft.), frequently from about 2.3 to 18.5 g / m3 (1 to 8 grains / cu.ft.), are freed from the solids so effectively that the problem of solid impurities and their accumulation in the S02 recovery process is practically eliminated . Furthermore, one observes, as already said; When pre-sprinkling with a vat there is a considerable decrease in the concentration of sulfur trioxide in the exhaust gases, and furthermore that this absorption of SO3 by the water takes place selectively, that is, without any significant absorption of the sulfur dioxide present. As already discussed above in connection with this special S02 extraction process, has a beneficial effect in removing the Sulfur trioxide from the chemical absorption zone occurring exhaust gases in that the amount of potassium sulfate formed in the chemical absorption is decreased, which is why the need for an expensive separation of potassium sulfate crystals from the potassium pyrosulfite crystals is hardly or no longer given. Since the sprinkling water finally selectively absorbs the sulfur trioxide, practically all of the dioxide remains in the gages and can be absorbed by the potassium sulfite and, if necessary, subsequently obtained from it as liquid sulfur dioxide with high purity.

3e according to the content of suspended solid matter in the to be treated According to the invention, the pre-sprinkler mare is so effective that it also when used alone may be sufficient, the content of suspended solids reduce so far that the absorption treatment with the aqueous potassium sulfite solution can be performed satisfactorily. The pre-irrigation can generally at least about 75% by weight of that present in the exhaust gases upon entry into this stage Solid particles are removed, often up to about 99 or 99.9% of that Solids are removed.

In the case of exhaust gases with a very high solids content, it may be desirable be to include a stage for removing the solids upstream of the pre-irrigation, for example by pre-cleaning devices by first turning the gas stream, for example by electrostatic separators or cyclone separators or by combinations these bodies conducts to some of the particles, especially the larger ones Particles, to remove. In any case, with a gas with a certain content on solid suspended matter by using pre-sprinkling with 'Nasser in accordance with Invention of the solids content to be reduced to an acceptable 'Nert, far fewer separators and centrifuges are required than usual.

The concentration of the SO3 present in the exhaust gases, which can be treated by the method according to the invention, depends on the origin of the respective gases. Even if certain SO 2 -containing exhaust gases e. Do not contain any suspended solid matter but only SO3, the present method can effectively be used to remove the SO3 prior to contacting the exhaust gases with the potassium sulfite absorption solution. In this case, the advantage achieved by pre-sprinkling, as already mentioned, is that the formation of unmashed potassium sulfate in the chemical absorption solution is reduced. The present process is therefore suitable for the treatment of SO2-containing exhaust gases which additionally contain solid suspended matter or sulfur trioxide or both. If the gas contains very little suspended solids, e.g. less than about 0.5 grains / cu.ft., Then it may be desirable to add particulate solids, such as fly ash, to the gas stream to achieve this Activating and adsorbing S03, whereby an effective removal of the adsorbed S03-containing particulate solids is guaranteed by the pre-sprinkling.

The apparatus and method used in the system described herein for the extraction of S02 from gases and for the subsequent extraction of the S02 in one relatively pure form used have other characteristic features Merk-`paint.

One of these features relates to the apparatus and method and refers to the use of one over the Gasz__. conductive cap, which protrudes into the reactor and d @ prevents the liquid in the vessel with the entering gases at the inlet opening comes into contact and that solids be removed from the gases that accumulate at the exhaust port of the inlet port and the gas inlet opening can clog.

Another feature also relates to the apparatus and method, and relates check on the reactor comprising a Reakti onszone SADR t ellt, at least Eire or having clock floors several -Kort = taken from below with the aqueous salt solution, Z.8. a sulfite solution, can be sprayed.

Another feature relates to a defog zone for Removal of droplets of the reaction product from the gaseous products of the Reaction zone, being a material from a 1, mesh fabric as well Spray devices for spraying the material from both sides with a solution, e.g. a sulfite solution can be used.

Another feature relates to the separation of the 13isulfite by evaporating the water from the bisulfite solution, 2.B. in a rapid evaporation chamber, for the purpose of supersaturation of the solution and precipitation of the bisulfite in an amount that for example approximately equivalent to the amount of sulfur dioxide removed from the exhaust gases is. In the case of the precipitation, such conditions are expediently observed that Obtain crystals of a size suitable for filtering on a vacuum drum will. The crystals are expediently redissolved before they are used for regeneration of sulfur dioxide are heated. Part of the solution thus formed becomes expediently in an approximately saturated state for, Paschen and for improvement the purity of the crystals used on the drum filter.

Another feature relates to the use of multi-level Stripping columns and on increasing the concentration of the introduced into the column Crystal pulp. Another feature relates to the use of an inert gas as a stripping medium in a column used to recover gaseous sulfur dioxide from the bisulfite produced in the process and for concentration ier sulfite-bisulfite solution is used from the reactor before it is introduced into the stripper column will.

The invention is based on the accompanying drawings and the following given example explained in more detail; however, these are not intended to be limiting of the invention.

FIG. 1 shows a flow diagram of a system for the production of 502, in which the subject of the present invention in an advantageous embodiment is included; Pigur 2 shows an enlarged schematic view of the absorption column 10, in the system of Figure 1; Figure 3 shows a section through a unit for removing particulate solids or in liquids soluble contaminants from a gas stream; Figure 4 shows a plan view a pad for a packed column; Figures 5 through 11 show three useful ones Cap constructions; and Figure 12 is a flow diagram of a system for recovery of S02 with a modified decomposition zone.

According to Figures 1 and 2, a sulfur dioxide-containing gas stream, e.g. exhaust gases from a Kraftvierkes or exhaust gases from an industrial plant, e.g. a sulfuric acid plant or an aluminum plant, is fed into a reactor 10 with an inner diameter of about 80 cm (30 inches) made of a corrosion-resistant steel of type 304 and with a lining 9 which is resistant to weak sulfuric acid and which is made of corrosion-resistant material, for example made of lead or a suitable plastic. The gases pass through line 12 which is approximately 30 cm (12 inches) inside diameter. The reactor is approximately 6.4 m (2..1 ft) in length at points D-13. The quantities and speeds for the gases and liquids specified in the description relate to a reactor with this internal diameter, ie an area of about 0.55 m2, (4.9 s (If t.) And the specified distances between the components arranged in the reactor.

It is of course clear to a person skilled in the art that the quantities and speeds the gases and liquids used on the size of the reactor used and the distances between the components in the reactor depend, but these can Deviations are viewed as equivalents within the scope of the invention. Although the invention using potassium as the metal in a "metal sulfite-bisulfite system is described, it is also applicable to cesium or rubidium sulfite.

The concentration of sulfur dioxide in these gases generally carries about 0.001 to less than about 5 mol-δ and is often less than about 0.5 P, 4.1- ° 1 (about 1 Ge, rr .- # o). For example, in a modern power plant, 1,350,000 k'7 burned around 15,000 tons of coal per day. Many types of coal contain around 3.5 wt .- # o sulfur or more. The data from a system of this size when used The amount of sulfur dioxide emitted from this coal would be produced then be about 1,000 tons per day, although the consortium concentration of sulfur dioxide in the flue gases is very low may be rig, for example on the order of about 0.2 to 0.3 r, 2O1-lo, which depends on the sulfur content of the coal. It can be larger amounts, for example of more than about 75 Ge: 7th, shriek dioxide can be removed from these gases. The exhaust gases can also contain S03, but it fluctuates S03 concentration depending, among other things, on the Gas source and the flames used in operation - temperatures. It is usually no higher than about 0.01 mol%, based on the gas, and normally liemt in the range of about 0.0001 to 0.01 1! 4o1 -, '. 0. Ordinary is the main part, for example more than about 70%, of the SO3 in the gas on the surface of the particulate solids beer. A particularly advantageous feature of the pre-brushing It also consists in the fact that it is able to process small quantities (e.g. about 0.00001 to less than -about 0.005 @ 4 @ 1- :) to remove liquid-soluble components in the gas stream. This is particularly advantageous, especially if the gas is in the Pre-scraper is treated as described nac'na >> z- # izen; i- ben is, and the remaining amounts of S0, ir. der: in the pre-cleaner to be treated n gas minimal si Zier Gasstror: in the loan.:, 14 has in the a11gE: _ .: a @ r @ a temperature r; @tur from to z @ = @ twa '. '.,; ° ^) cf-c from about 66 to 316 ° C (150 b @ .s 6T10 ° F @ ").. Ir d`; suitable learn Gas streams include, for example, exhaust gases from power plants that burn coal or oil (typical temperatures in the range of about 120 or 1500C to 180 or 205 ° C), exhaust gases from sulfuric acid plants (typical temperatures in the range of about 66 to 930), and exhaust gases from smelting furnaces (temperatures up to about 4300C). However, at temperatures greater than about 205 ° C (400oF) it may be desirable to cool the gas to a temperature of about 107 to 1500C (2.25 to 3000F), e.g. iurgb cooling with room air in order to avoid an adverse effect on the reactor, the reactor lining or the pre-cleaning operation. If the gases have a temperature less than about 660C (1500F), it may be desirable to heat the gas in the newspaper 12 in order to remove the water. to promote the solution in the reactor 10. The exhaust gases generally have a relative humidity of up to about 10%, usually from about 1 to 7%. The blower 28 (see FIG. 1) which removes the stripped gas from the reactor can, if desired, also be arranged to blow the gas through the reactor. Those from reactor 10 Stripped gases through the chimney and through Gases entering line 12 can, if desired, be passed through a heat exchanger (not shown) with heat exchange in countercurrent.

The sulfur dioxide is absorbed from the gas stream in zone 30 of the reactor by reaction with an aqueous potassium sulfite solution, an aqueous potassium bisulfite solution being formed, and the stripped gases are vented through chimney 14. Although potassium sulfite is used in this example, the corresponding sulfites of cesium can also be used. or rubidium can be used. . The gases (e.g. exhaust gases) entering through line 12 will go under the over the inlet opening of the Newspaper 10 arranged cap 13 in the reactor 10. The Cap 13 extends a certain distance into the reactor and prevents the water or solution from getting in Inlet opening of the newspaper 12 can get. You prevent advantageously prevents clogging of the inlet line 12 by components such as Plugaache, which are in zone 20 the gas is removed. The cap 13 _ @. Agt in a small Angle upwards, which gives you a feeling of being close to the wall of the Reactor 10 and-around the inlet of line 12 run . can, which is flush with the wall of the reactor 10. The angle of the cap 13 is generally about 5 dis 60 °, in front of about 10 to 45o, zH 30c and the knife of the cap 13 is at least equal to the diameter the inlet opening of the line 12, e.g. about 30.5 cm (inside durohmesser). The top of the cap in tone 20 is so far from the can. 25 removes that the spray jet'1 will not be destroyed, but still so close that a überdißiae Evaporation of the Rebele from the spray jet and a downward dropping of drops from the point of impact is prevented. This distance is in the arrangement described here generally about 13 to 180 cm, suitably about 25 to 75 cm, right about 38 cm. All plush things that happen on the Wall of the reactor 10 runs down or onto the upper surface the cap 13 strikes away from the inlet port and directed to the wall of the reactor 10 without it directly passes in front of the inlet opening. Figures 5 to 11 illustrate three useful cap- pen constructions. In Figure 5 ', the cap 13' protrudes outward and up into the reactor at an angle of about 30o. The hood 13 'of FIG. 6 has the shape of a half tube with grooves 15' which run back along the edges to the wall of the reactor 10. The cap 13 ″ of FIG. 7 likewise projects into the reactor 10 at an upwardly directed angle, to be precise from the inlet opening 12 ′ of the line 12 to the outside. The cap 13 ″ is cut at an angle (represented by the area 1511) in order to distribute the gas entering from the newspaper 12 over part of the diameter of the reactor 10: The cap 13 ″ can, for example, be punched from a flat sheet metal and has no gutters on the edge, although these may be present if desired. The cap 13 ″ is particularly suitable for a gas flow with a high solids content. FIGS. 9 and 10 show a cap 13 "', which represents a pipe running transversely to the diameter of the reactor 10. A slit 15''' which tapers to a point (cf. FIG. 11) distributes the gas entering from the line 12 over the Diameter of the reactor 10. The channels 15 ″ 9 # 9, which are attached to the cap 13111, collect the liquid and the solids so that they can run off to the wall of the reactor 10. The cap according to FIG 7 and 7, formed and protruding about 30 cm (12 inches) into the reactor 10. The inlet of conduit 12 is about 30 cm (12 inches) and the inside diameter of the cap is slightly larger than the inlet of newspaper 12. The cap is about 38 cm (15 inches) below the spray nozzles 25 and the grooves on the cap are about 25 mm deep. When the cap was used, there was no clogging of the inlet opening, while in the absence of the cap there was an exhaust gas with a solid content from about 23 9 / m3 (about 10 grains / au.ft.) a blockage of the inlet opening occurred in about 2 to 4 hours. The reactor 10, which is advantageously designed as a single vessel in the arrangement shown, contains three zones which, if desired, can also represent separate units. These zones are a pre-shower zone 20, an absorption or reaction zone 30 and a zone 40 for removing the moisture or for defogging. The exhaust gases entering the reactor 10 first pass through the pre-shower zone 20, in which solid constituents in the form of te.i-lc-hen such as fly ash, and water-soluble constituents such as SO3, hydrocarbons including methane, ethane, propane, etc., selectively from the SO 2-containing gas can be removed; the SO2 contained in the gas is in turn removed from the gas in zone 30. Since most of the SO3 in the gas is usually adsorbed on the surface of the solids contained in the gas, it is generally removed along with the solid particles. The solids contained in the gases, for example dust, are generally unreacted substances, such as fly ash, which are produced by the chemical plant, or incombustible components of the fuel.

The chemical composition of the fly ash naturally depends on the type of fuel burned; however, the ash is usually composed largely of silica, alumina, and iron, the oxides of other metals, such as manganese and vanadium, often being present in smaller quantities. Other suspended particulate solids which may be present in the exhaust gases are, for example, particulate hollow carbon spheres which occur particularly in the exhaust gases from oil burners and which, like the fly ash, contain considerable amounts of adsorbed SO 3. The particle size of the solid floating '#l Jffe in the exhaust gases can be about 0.5 to 50 microns, but can also be a lot to be taller. However, the majority of the particles are sized up to about 10 microns. For example, the fly laundry in an exhaust gas that from a coal plant fit turbine grinding of the coal was testified to the following particle size distribution Size in microns wt% of total ? bag 0-10 86 10 - 20 5 20 - 40 4 40 - 60 5 In a coal plant with cyclone-fed coal grinding , the fly ash in the exhaust gas had the following particle size distribution: Size in microns by weight - 1% of the total Fly ash 0-10 45 111: - 20 23 21-45 20 45 - 12 The pesticide content in the gases can be about 2.3 mg to about 140 g per m3 of gas (0.001 to 60 grains / cu.ft.); In the case of exhaust gases, it is generally about 2.3 to 23 9 / m3 (1 to 10 grains / cu.ft.). If the solids content of the gas is very high, ie generally more than about 2.3 g / m3, 2.H. about 2.3 to 23 9 / m3 in exhaust gases from power plants (these usually contain et "-ra 2.8 to 9.3 9 / m3) and the gas contains in particular large particles, for example with maximum dimensions of more than about 1.6 mm (1/16 smell), it may be desirable to dedust the gas beforehand, for example in an electrostatic separator or in a cyclone separator (see FIG. 3) before it is introduced into the newspaper 12. In general, about 80 to 90% of the particulate solids can be removed with a cyclone separator and an even larger amount with an electrostatic separator, which is more expensive than the cyclone separator.

Although by switching on devices such as electrostatic Separators and centrifuges, e.g. dry cyclones, between the exhaust gas source and the chemical absorption zone easily receives the bulk of the larger solid impurities is removed, it has heretofore required a large number of such devices to be connected in series or in parallel in order to practically completely cut off these solids before contacting the gases with the absorbent solution. This leads to high operating and investment costs. A special advantage - the pre-irrigation is that also minimal amounts, e.g., about 2.3 mg up to about 2.3 g of particulate Solids per m3, which are caused by a cyclone separator or an electrostatic Do not allow separators to be removed, they can be removed. Are they not removed so they have an adverse effect on the system; continue to let yourself by pre-sprinkling effectively and with low investment costs.

The sprinkling water is introduced into the lower portion of the reactor 10 via the newspaper 24 and splashes in the form of a fine spray jet through the spray nozzle 25 up. The openings of the spray nozzles are so large selects, d = Iß about 6.7 cm3 of liquid per m3 of gas per minute (0.1 gall / 2000 cu.ft. x min.). The public nungä @ .rin ': el is generally about 10 to 125o, e.g. 75o, and the droplets generally have a size of about 200 to 800 microns which is beneficial for removal of solid particles with a size of up to about 60 microns ron is. The temperature of the sprinkling liquid (e.g. Water) is generally about 10 to 500C (50 to 1200F), preferably about 21 to 320C (70 to 900F). It several nozzles can also be used, as shown in gur 2 is shown. At a distance of about 10 to 46 cm (4 to 18 inches) e.g. about 23 cm (9 inches) above of the nozzles 25 there is a practically horizontal orderly, for fluid media (gases or liquids) permeable impact surface with an only slightly cohesive hanging surface. It preferably consists of columns or tubular elements that form a lattice-shaped hal- form sertion 15, which is preferably made of an expanded metal, For example, from corrosion-resistant steel, is formed: On the Bracket 15 is the Fül.lkörperma-material 22, which consists of about three layers of irregularly oriented, non-porous Packing elements such as Raschig rings, Intalox or Bgrl. Saddles, preferably made of ceramic L material C> is. The longest dimensions of each element are about 6.3 mm to Q.9 cm (0.25 to 3.5 smelt), e.g. about 38 mm (1 1/2 smelled). The elements form a packing per column generally about 38 to 140 mm (1.5 to 5.5 inches) and preferably from about 75 to 100 mm (3 to 4 inches), weighing generally about 480 to 1100 g / hiter (30 to 70 lbs / cu.ft.) and one free space of generally et "rja 50 to 90 @@. '"' lie in the drawing ;; to be explained, the 3pz" ühd @ isen 25 so close to the base 15 that a coherent 'vas- serstralil with a Gesch -. @ jin_ligkeit that the Gravity over:, iin; let uni di.e contact surface and wetted. This speed is generally etL-ja 0.6 to 6 m / sec. (2 to 20 FPS), e.g. about 1.5 m / sec. (5 FP; 3). The wet reaches, touches and berx - +, 7t - the UnterlPge and the on it-2 F # -illkörperma material and falls in large Pot again, down, whereby the particle-shaped i.ge solid Material and the 003 that are removed from the gas stream, carries. The; 'lassers beam envelops the larger solid ones Particles through which they fall out of the gas flow while the water-soluble SO3 in the gas flow is partially is resolved. At 1: Iindurchs, the exhaust gas flows through the filling body material affects practically everyone, e.g. at least about 90 1, the smaller solid particles remaining in the gas and the S03 on the wetted surfaces of the packing material rials on and stick to it, forming drops that enlarge until the force of gravity and the adhesion to the surface of the material is so that they fall down or: through the '.'lasser- can be washed away from the packing material. In space- common can be more than 95 wt. O, for example more as 99 Ge ', i .- # c of the particulate solids from the gas removed. The distance of the S03 is particularly wishes that it can form potassium sulphate in this system, whereby the coagulation of the 30 2 is disturbed, for example in that the potassium sulfite is consumed, which is otherwise would be consumed by the S02. The exhaust gases entering the column via line 12 flow through the base 15 and the Püllkkörper layer 22 up. As a result, the gas is advantageously that it is in direct current with the liquid to a fluid medium (gases or liquids) fluids) permeable impact surface is conducted; the Gas directed to the impact surface has on contact with the impact surface such a speed that it in the presence of a liquid in the impact area can penetrate and penetrate through this, whereby the liquid at such a rate to the Impact surface is directed, ..- that the impact surface to Time of contact is wetted, the liquid but the Can penetrate the impact surface only insignificantly. Habitual Lich is the speed of the gas to the impact surface so large that a predominant proportion, e.g. at least 60% by volume, preferably about 90 to 100% by volume, through the Go through the impact area. In general, the approximate speed of the gas at the time of contact with the impact area about 0.6 to 4.5 m / sec. (2 to 15 FPS), preferably about 1.5 to 3.6 m / sec. (5 to 12 FPS), e.g. about 3.0 m / sec. (10 FPS). The velocity of the liquid at the time of contact with the impact surface is generally about 0.6 to 4.5 m / sec. (2 to 15 FPS), preferably about 1.5 to 3.0 m / sec. (5 to 10 FPS), e.g. about 2.4 m / sec. (8 FPS). The amount of liquid used is sufficient to effect a transfer of the particulate solids or the liquid-soluble components in the gas into the liquid in contact with the impact surface and depends on the amount of the particulate solid or liquid-soluble components in the gas; In general, the amount of liquid is about 0.7 to 67 cm 3 per m3_gas and minute (0.01 to 1 GPI4 / 2000 CFM) when the gas is about 1.2 to 70 g / m3 (0.5 to 30 grains / cu .ft.) contains particulate solid components; this amount of liquid is sufficient to dissolve the components which are present in the gas and which are soluble in liquids. The pressure drop of the gas through the packing layer 22 is generally about 6.3 to 12.7 mm (0.25 to 0.5), for example about 10 mm (0.4 inch) Waters column with a gas throughput of about 28.3 m 3 per minute. Furthermore, the liquid is hardly retained in the interstices of the packing layer. The liquid used can be any suitable liquid which does not chemically attack the impact surface and which does not adversely affect the exchange of foods, especially when it is a matter of a mass exchange of the non-solid constituents; a liquid is expediently used which selectively dissolves and removes the non-solid constituents. For example, water can be used for the selective and simultaneous removal of particulate solids and SO 3 from a gas stream. The solids suspended in the gases impinge on the wetted surface - the substrate 15 and the packing layer 22 and become These solids are washed away from the packing layer and the base by the used Alaschwasser falling down, which was held back by the impact surface and driven back -: The used wash water, the removed solids and the absorbed sulfur trioxide contains, flows under the action of gravity on the funnel-shaped sides of the collecting tray 17 of the column 10 and through the outlet line 26 for the used wash water to the outside. An important feature is the arrangement of a surface, for example the collecting base 17, as a drip catcher opposite the impact surface, the drops falling from the impact surface being removed from the zone 20 before a Evaporation of the drops mentioned may occur. on dieac:! `quietly. @ ir_l a return of the participatory Fests to f fe, z. ß. the fly ash, or that in liquids Soluble components, e.g. 13. S03, zur Aiifpr, illfl, # iclie under practically prevents the ingress of gases, ler @ t. Flat figure, 2 be tr, @ i-; t the distance z @, between the points aa e twa) e8 in, un, l the surface 17 is in a ', "linkel of 600 ve: reni.ibe r the exit 26 inclined downwards; t. Fixed pain : i to f'Ce «r1 l Se '11! 1 e fel tr, ioxyd are @iuf; Liese &quot; le: i ac from the Ahg @ i @ ic: n en t; f ern t, before 1e tz tere @; -t @ ii t of chemical ab- comes into contact. F: i1la: @re; @@ ünsclit, can that loses @ r @ iiic; h te ';' lascyi °: @a: »he who often pounds in front of / JU 2 1) is z1 can have (which depends on the set of @c: hNefe @ tri- oxy (Ia in the exhaust gases abli_in-t) for separation and, 'lic: clerge- the pesticides (e.g. fly ash) and the :; äur'c; @Ne il, E'rbeharidel t vrerden. A very beneficial feature times this before @ berie:, elurigsanor- # Inun :; Is it to you that ringe volumes of water can be used to remove the Moisten Aufpr @ allfl, icrie, which is particularly favorable is because the amount of water contained in the system; e the entire Zeis turiga ability of the procedure can influence. Of- halh it is desirable to use only enough water that the Aizfpr, allfl = iche is touched and wetted and the water fall back down and the particulate solids and that SO can collect. Generally less than about 6.7 cm3, preferably about 0.67 to 4.7 cm3, e.g. about 3.4 cm3 of water per m3 of gas and minute used (about 0.1 GFM, preferably about 0.01 to 0 a GPM, e.g. 0.05 GPM to 2000 CFIJI) o Those obtained using less than 6.7 cc Advantages are given in Table 1. By using the This pre-reading requirement is possible to increase of the moisture content of the direction 20 gases flowing to no more than about 8 to 10%, preferably 2%, and the temperature Abfail by the pre-sprinkler system is ini all- , Geiiieein less than et, especially 33 o G (60oF), vorzt @: @; free less as about 280C (50 ° f). The ver, r / eridt.ing of the sprinkler system, which in particular which is shown in V1guT '22, results in addition to elnein i.itlli@r': @ t gE ° .r'incen `1? E: rnperaturabfal1 un: l a nilriiin_il.eri Zun, -ihnie der relative humidity of the gas through the irrigation zone, ? "T ' _ @ F} @ ic @@ rj an ay a .. A-ho, rdriundie surprise- derwei.se no * constipation problems shows, ini Ge, Tsatz zti a preliminary selunga arrangement in which the '.'l @ isser, continuous nuierl.I sprayed on from above, vircl. With this arrangement en f;: @ teti t an appreciable tempera tumb fal 1., 7-9. about 55 ° C (100 ° F) uni a significant increase in relative Humidity, e.g. Lini eLva 10, °, o; one also steps iririerhnlb short time, e.g. within @ h: zlti of 2 hours, a verse toprunf, through the Fe:> ts to ffe removed from the G <i; s stream. the Arrangement of the spray nozzles on the underside of the impact surface enables a longer operating time, e.g. up to about 16 hours, without, Liese Vers-topfungsi) roblenie. If however, it can also be used in the sprinkler attach a second spray assembly 27, located above is located on the impact surface and the periodic, the. Device 29, a pressure regulator, active fours; this can be done every 8 to 16 hours, for example a period of 1 to 3 minutes, taking from above a beam is directed onto the impact surface, whereby- is flushed through the packing material and a continuous proper operation is guaranteed. The absorption or reaction zone 30 is more advantageous- wisely constructed in such a way that an intimate contact in the Countercurrent to each other flowing gas and liquid currents is guaranteed, although, if desired, can also be designed for direct current operation. , Never shown in the drawing, the absorption cut in the form of z ", tear practically horizontal sieve trays constructed, which can be of a known type, for example. It however, bubble cap trays can also be used. The gases are moved at a speed through the reactor 10 conducts sufficient liquid to puf the contact floors to hold, but not so big that the liquid is blown out of the reactor. Typical average velocities of the gases through the absorption section 30 of reactor 10 are generally at least about 45 cm / sec. (1.5 FPS) and expediently about 60 to 260 cm / sec. (2.0 to 8.5 FPS). The potassium sulfite solution is passed through the newspaper 16 into the reactor 10, generally at a rate of about 6.7 or 27 to 1350 cm 3, preferably about 135 to 540 cm 3 per m 3 of gas per minute (0.1 or 0.4 to 20 GPM, preferably about 2 to 8 GPM per 2000 CFM of gas) and the potassium bisulfite solution is removed through line 18. The potassium sulfite, which generally makes up about 40 to 60% by weight, for example about 50 lo of the total solution to be introduced, is introduced from the newspaper 16 through the line 16111 and the Leituna'44 'of the defogging device 40, falls onto the surface of the Bottom 32 and flows from bottom 32 to bottom 34. If desired, further solution can be added through line 16 '. The potassium sulfite reacts with the sulfur dioxide in the gases flowing through the sieve trays, forming an aqueous solution of potassium bisulfite which flows from the bottom 34 into the catch basin formed by the downwardly protruding plate 36 (FIG. 1) where from * it is removed through line 18. The sulfur dioxide content of the gas is thereby greatly reduced, for example to less than about 0.02 @, Iol- #. with a flue gas that contains more than about 0.2 mol-3i. The Kaliumbi: ulfit is separated, z. B. crystallized and can be recovered in crystalline form as potassium pyrosulphite, which is then decomposed to potassium sulphite and sulfur dioxide. The potassium bisulfite is converted into potassium pyrosulphite during the crystallization liquid product can be compressed or fed as a gas into a sulfuric acid plant or into a reduction furnace for conversion into elemental sulfur. The potassium sulfite can be returned to the reaction zone where additional sulfur dioxide is absorbed. The lay reactions used for the invention are as follows: I. K2503 + S02 + H20 --l> 2KIIS03 II. 2KHS0 3 cool K 2 S2 0 5 (kr) + H 2 0 III. K2 S205 heat 82S03 + SO 2 (g) So that reaction I takes place, the temperature of the solution in the absorption or reaction zone 30 should be kept above the temperature at which the sulfur dioxide is absorbed by reaction with the aqueous potassium sulfite solution, and below the temperature at which the potassium bisulfite decomposes or reaction III sets in, e.g. below about 1100C (230 ° F) at normal pressure. The cooler the potassium sulfite solution, the more easily the sulfur dioxide is generally absorbed by the solution and reacts with the potassium sulfite. In the case of smoke or furnace gases, however, the temperature of the solution is generally higher about 320C (900F) or about 380C (100 ° F), although also room temperature is suitable. Preferably the temperature is maintained below about 880C (1900F), for example at about 50 to 82 or 850C (120 to 180 o, ler 1850F), as above = alb this Temperature ranges cl ie RE:; ik t ioci I so far to slow down seeds begins that the Scr); @ refelclioxyd no longer so easily goes into solution, since the partial pressure of the Sch, ziefeldioxyds gets high. As the stripped exhaust gas eventually, after the Treatment in the defog zone 40 in. _ -Ern chimney removed it is desirable to keep the temperature of the to keep pure gases so high that they still so that they rise up in the chimney (e.g. if there is more than about 850C). At lower temperatures, e.g. B. at about 570C (1350F), a blower can be used to remove the gas whom; let be. In general, the temperature of the Gas between the absorption zone 30 and the defogging zone 40 about 50 to 820C (120 to 1800F) e.g. about 570C (1350F). The temperature of the stripped gas in the outlet outlet line 14 of the defogging device is generally generally about 43 to 770C (110 to 1700F) e.g. about 540C (1300F); however, this can be increased if desired by blowing a hot furnace gas through the newspaper 14 ' leads. In general, this is from the defogging device 85 do- escaping gas is about 100% saturated with water. ?, @ -, -, km-moderate potassium sulfite solution is also used against the under- ; "ite of the floors 32 and 34 sprayed through the spray elements 38. The elements 38 generally have a stood from about 10 to 45 cm (about 4 to 18 smelled), e.g. from about 23 cm (9 inches) from their respective bottoms. The GE- the speed of the liquid is so great that the force is overcome. As soon as the potassium sulfite solution is on is formed in the soils, the water is caused by the hot ones Removed exhaust gases from the Usun, so that the solution can be saturated and potassium pyrosulfite t au @ crystalline that can clog the floors. That is why potassium sizlEitlösun! z = iiu, the line 16: for the line 16 '' zii headed the Sprütiele? i @ en teri. The spray:> drops are countered the underside: triple floors, on which the hot waste gases first come into contact with the i3 @ i; ien; come because to the- This point is the evaporation of the acid and thus also the Crystallization is strongest. a sufficient one rrIe solution upwards against the underside or cont7-ilct- area of the soils i; espriiiit to the solids in the solution to keep loosened on the floors, especially on the upper area where the exhaust gases impinge; on this, tit will ensured continuous operation of the process. It is desirable to reduce the amount of the spray elements to keep the managed solution as low as possible, and in general mean the amount of the solution is less than about 6.7 cm3 or 27 cm 3 per m3 of gas and: 1 minute (0.1 or 0.4 GPM / 2000 CFM). The higher the temperature of the exhaust gases, the higher it is Menäe of solutions that are fed to the spray elements 38 got to. For example, in the case of gases that have a temperature entering reactor 10 at about 150 ° C (300 ° F), one Solution amount of about 6.7 to 13.5 cm 3 per m3, gas and minute (0.1 to 0.2 GPM / 2000 CFM) is appropriate. The potassium sulfite solution is in such an amount by the absorption section 30 passed that it with the heavy field dioxide in the exhaust gas react, ie the sulfur dioxide in absorb the solution and form potassium sulfite. in the in general, these are stoichiometric amounts, and one can advantageous a solution that includes about 25 Ge@N.-u'o K2 S03 and Contains 25% by weight of KHS03. The potassium sulfite solution introduced into the reaction zone is 1 ..; ,,% a returned stream and contains im .:; l: emein about 30 or 40 to 75% by volume, preferably 40 or 50 to 65% by weight of solids, which are generally m "iiien at least about 50%, preferably more than c F: vsa 75 c consist of potassium sulfite,: while the rest im ,.; ;, ;; release from potassium bisulfite and possibly something `.'u1Cat exists. This returned current is preferential @ise a saturated potassium sulfite solution. The potassium sulfite 1 ;; 3ung can be a sufficient amount --ez "ries Oxidationsin- contain hibitors, e.g. hydroquinone (about 0.001 to 0.1%), which prevents the sulfite ion from being oxidized. : rird. The temperature of this stream is controlled so that the conditions in the reactor 10 are not disturbed. The temperature of the recirculated stream is usually about 32 to 710C (90 to 160 ° F). In general, a sufficient amount of potassium sulfite solution is brought into contact with the exhaust gas in reactor 10 in order to remove as much sulfur dioxide as possible, preferably more than about 90 to 95 4, the residence time of the solution in the reactor being adjusted accordingly. The flow rate of the solution in the absorption zone 30 is normally set so quickly and the residence time of the solution in the absorber is generally chosen to be so short that no crystallization problems occur in the absorption zone. If the flow rate is slow and the residence time is long, the sulfur dioxide is completely absorbed; however, the solution becomes very concentrated, which increases the risk of crystals separating out of the solution and clogging of the sieve trays. The flow rate of the solution depends on the gas temperature, the SO 2- @ Ilenge in the gas, the temperature and the concentration of the potassium sulfite solution; however, it is generally about 6.7 to 1350 cm3, preferably about 135 to 540 cm3 per m3 of gas and minute (0.1 to 20 GFM, preferably about 2 to 8 GPM / 2000 CF214 gas). About 5 to 25% of the solution can be introduced through elements 38. The sheet 36 forms a collecting trough or a collecting basin for the potassium bisulfite solution. The plate 36 can be inclined, for example at an angle of approximately 10 to 450 (or also horizontally), so that all the crystals contained in the potassium bisulfite solution flow downwards to the line 18. A relatively thick layer of solution, for example from a few decimeters to about a meter (e.g. -about 20 cm), is kept on the plate 36 in order to prevent the formation of crystals in the solution; preferably the residence time in the collecting basin is short, for example generally about 5 to 10 minutes.

The product from the reaction zone is preferably saturated Solution of potassium bisulfite, which is why the concentration of the solution is expedient below the saturation point where a sufficient amount of `wet is added to avoid precipitation of the potassium bisulfite. 'Vie already mentioned above, potassium pyrosulfite would crystallize out in this case.

The solution obtained when an aqueous potassium sulfite solution is reacted with a flue gas naturally contains many components; An example is given below: Range (wt%) General Ordinary Potassium sulphate 0 - 8 1 - 6 Potassium bisulfite 5 - 40 10 - 30 Potassium sulfite 10 - 50 20 - 45 Water rest rest lies The sulfur dioxide / in chemically bound form, $ .8. as Potassium bisulfite, which can be seen as a precursor for Schlvefeld dioxide in the solution and which is present or in contact with substances that lower the partial pressure of the SO2, e.g. with metal salts, such as alkali salts, generally the potassium salts, such as unreacted potassium sulfite and potassium sulfate, which is formed by the reaction between sulfur trioxide and potassium sulfite. The purity of the potassium bisulfite in contact with the substances that reduce the SO2 partial pressure is usually less than about 60% by weight, based on the dry substance.

The amount of solids in the solution depends on the temperature, but is generally chosen so high that the sulfur dioxide can be obtained therefrom in good yield. There is generally about 40 or 45 to 75 weight percent, preferably about 45 or 50 to 55 or 65 weight percent solids in the solution. The amount of potassium bisulfite and potassium sulfite in the solids depends on the total amount of solids and the temperature of the solution. In general there is about 5 to 50 or 60% by weight, preferably 10 to 35 or 50% by weight, of potassium bisulfite and generally 40 or 50 to 95% by weight, usually about 50 or 65% by weight 90% by weight as potassium sulfite. For example: at about 250C (770F) a saturated aqueous solution of potassium pyrosulfite and potassium sulfite contains about 5 40 potassium pyroeulfite and 47% potassium sulfite; at about 400C (1040F) such a solution contains about 7% pyrosulfite and 48% sulfite; at about 650C (1490F) the solution contains about 12 % pyrosulfite and 48% sulfite.

The stripped off gases in reactor 10 pass from the absorption reaction zone 30 in the moisture collection or defog zone 40, which is a contact surface in shape a mesh fabric contains. The pressure drop of the gas through zone 30 is: generally about 38 to 115, e.g. about 63 mm column of Ilass (1.5 to 4.5 e.g. 2.5 inches @ water column) with a gas throughput of about 57 m3 / t? In. (2000 CFM). The mesh fabric 42 consists of a material that is opposite to the components the system is chemically inert, e.g. made of corrosion-resistant steel of type 304, and has a certain resemblance to steel wool in terms of structure and appearance; in FIG. 2 it is indicated that it lies on a support 43 of the column. Potassium sulfite solution from newspaper 16 goes through line 106111 and newspapers 44 'and 46' the nozzles 44 and 46, respectively, which generally smelled about 10 to 45 cm (4 to 18 inches), e.g. are approximately 23 cm (9 inches) from layer 42 and are continuous with the solution spray onto mesh 42 from opposite sides the arrangement, namely from above (side of the liquid outlet) and from below (Side of the draining liquid), which eliminates clogging problems and continuous operation can be guaranteed. The defog zone 40 is used to remove droplets from the gases coming out of the reactor 10, whereby Chemical losses are avoided .. The droplets can be liquid or solid Represent shapes of the reaction product and are generally so small (e.g. about 1 to 100 microns) that at the speed of the ascending gas stream, which is usually about 60 to 210 cm / corner. (2 to 7 FPS) can be carried away. It was. Surprisingly found that when using a mesh fabric structure gets by with small amounts of solution for the contact material. But it can also be a Material with a large and highly wettable contact surface, e.g. Raschig rings, can be used, but larger amounts of solution, e.g. about 1000 cm3 / min. needed will. The thickness of the defog zone 40, which is, for example, about 2.5 to 10 cm, is sufficient to remove the droplets from the exiting gases, but again not so great that a strong pressure drop is generated; the. Gas flow through the defog zone 40 is below the point at which droplets emerge from the contact area would be carried away again. The maximum permissible pressure drop is generally about 6.3 to 13 mm `, vassers = iule, and in general are gas velocities from about 60 to 180 cm / sec. suitable. In general: the defog-s-zone @ so much solution is supplied that clogging of the defogging device is avoided, but on the other hand an entrainment in the escaping gases is prevented. These Defogger is very powerful and only needs a small amount Solution. For example, generally about 135 to 335 or 400 are preferred about 300 to 230 or 270 cm 3 of solution per m3 of gas per minute is suitable (2 to 5 or 6, preferably about 3 to 3 1/2 or 4 GPM solution / 2000 UM gas) which is preferably be evenly divided between the nozzles 44 and 46. The amount of solution used decreases as the concentration of the solution decreases, and it is desirable that the flow to keep it as low as possible. The defog zone 40 also serves to prevent the last Remove traces of sulfur dioxide in the escaping gases. Example circles: earth Normally another 1 to 2 P! ol-'4 of the total sulfur content through the defogging device the incoming exhaust gases removed.

In this system, sufficient amounts of the substances which lower the SO 2 partial pressure are separated from the potassium bisulfite, whereby the partial pressure of the sulfur dioxide in the potassium bisulfite is increased. The substances that lower the SO 2 partial pressure can be separated off in any desired manner, for example by selective extraction of the potassium bisulfite from the solution or by extraction of any substance that lowers the SO 2 partial pressure from the solution. The separation is preferably carried out by crystallizing the potassium bisulfite (which turns into potassium pyrosulfite during the crystallization) from the solution and further treatment in the system, as indicated below.

The release of sulfur dioxide from a precursor, such as potassium pyrosulfite, depends on its partial pressure under certain conditions, such as whether it is with other substances, including salts; lvie potassium sulfate and potassium sulfite, which are generally present in the solution obtained by reacting the flue gas containing sulfur dioxide with the aqueous potassium sulfite solution. The partial pressure of the sulfur dioxide in its precursor in the presence of other substances, e.g. potassium salts, in the solution of the reaction product, at its boiling point under normal pressure conditions, is so low (for example it is about 1.5 mm Hg in an example given below), that the sulfur dioxide cannot be released economically. On the other hand, its partial pressure is relatively high when the potassium pyrosulfite is present in a relatively pure form, for example in a purity of more than about 98% by weight (as dry substance). In this case it is about 300 mm Hg. The purity of the potassium pyrosulfite is generally increased according to the invention to more than about 65% by weight of G, preferably to more than about 90 to 95% by weight. The table below shows the partial pressure of the sulfur dioxide in potassium pyrosulfite at the stated purity. Tab 1 1 e Purity of K2 S205, partial pressure of S02, Weight # 4, (based on mm Hg Dry matter 65 5.0 70 6.1 75 8.5 80 _ --13.3 85 21.0 90 33.5 95 75.0 98 300.0 The potassium bisulfite "can advantageously be in the form of Ka- liumpyrosulfits can be separated from the solution by crystallization of substances which lower the SO 2 partial pressure. The crystallization of potassium pyrosulfite can take place according to suitable crystallization processes, for example by supersaturation of the solution by heating in vacuum or advantageously by cooling the aqueous potassium bisulfite solution to a temperature at which a larger proportion of the pyrosulfite crystallizes, e.g. below about 38 or 430C (100 or 1100F) , the lower limit being determined by economic considerations. For example, if a saturated potassium bisulfite solution is cooled from about 650C (1490F) to about 400C (1040F), about 40% of the pyrosulfite crystallizes out, whereas when the solution is cooled to about 250C (770F) about 70% of the pyrosulfite crystallizes out. Since potassium sulfite is more soluble than potassium bisulfite, practically pure pyrosulfite crystals (e.g. with a purity of more than about 95% by weight) can be obtained.

The potassium pyrosulfite crystals can, for example, by centrifugation or filtration and separated under atmospheric pressure to the appropriate decomposition temperature heated these temperatures are generally higher than be about 380C (about 100 ° F) and sufficient to decompose the potassium pyrosulfite. These temperatures are e.g. more than about 1100C (2300F) up to about 3160C . (about 600 ° F), but preferably below temperatures at which greater Form amounts of potassium sulphate, e.g. at around 2040C (4000F), preferably at more than about 1500C (3000F), essentially under anhydrous conditions. Here the sulfur dioxide is released, and the potassium pyrosulfite turns into the potassium sulfite converted that can be reused. It is not with this decomposition need to evaporate large amounts of water to release the sulfur dioxide when anhydrous conditions are desirable. That obtained from the decomposition of the crystals hot Kalit'msulfit is with the filtrate, which with the separation of the potassium pyrosulfite obtained, combined and returned to the reaction zone.

According to Figures 1 and 2, the potassium bisulfite solution is through the line 18 removed from the reactor 10 and passed to the intermediate container 48, from which it quickly (e.g. with a dwell time of only about 5 to 20 minutes in the intermediate container) is pumped out to a significant cooling and crystallization, which leads to clogging in the container lead 4hurdles to avoid. It is with the help of the pump 54 by the Newspaper 52 is fed into the rapid cooling crystallization zone 50. With the newspaper 18 a newspaper 18 'is connected to break the vacuum. The one through the newspaper 52 pumped solution can, if desired, be passed through a filter 56 to Remove solids from the solution. The rapid cooling crystallization zone 50 contains a rapid evaporation chamber 58 in which the solution is advantageously evaporated of the water can be cooled as well as a Crystallization tank 60. The high-speed evaporator chamber 58 is opened with the aid of the steam jet pumps 62 and 64 kept under vacuum, generally under a pressure of about q035 to 0.28 ata (about 0.5 to 0.4 p.s.i.a.), usually under a pressure of about 0.056 to 0.1 ata (et "-ja 0.8 to 1.5 p.s.i.a.). With the help of these steam jet pumps, a vacuum of about 0.035 ata (0.5 p.s.i.a.) can be generated. As indicated, the steam jet pumps generate 62 and 64 through the newspaper 66 a vacuum in the chamber 58. The pressure in the chamber 58 is regulated by the addition of air through the newspaper 68, which also increases the temperature the solution is regulated. The pressure regulation regulates the boiling point and the temperature drop and thus also the temperature of the solution in the flash evaporator chamber and the amount of water evaporated from the solution. Through the '.Yärmeausta.uscher 70 in the newspaper 66 is the '-'lasser which has evaporated from the solution in the chamber 5n condensed. The condensates flow through line 72 to the dissolving tank for the potassium pyrosulfite crystals. The steam from the steam jet pumps 62 and 64 is also condensed, goes through lines 74 and 76 and can be used later in the System can be used.

The solution in chamber 58 is normally cooled to such an extent that potassium pyrosulfite crystallizes out, ie is removed from the solution, in such an amount that the sulfur dioxide absorbed from the gas stream in line 12 is compensated for, whereby the correct balance of solids in the solution to be returned is maintained. The potassium bisulfite crystallizes out as potassium pyrosulfite. The amount of potassium pyrosulfite crystals removed depends on the degree of conversion of the potassium sulfite to bisulfite in the scraper; In general, about 3 to 15 parts by weight of potassium pyrosulfite crystals are removed per part by weight of the sulfur dioxide absorbed from the exhaust gases. If the degree of conversion of sulfite to bisulfite in the aqueous solution passed through the reactor 10 is, for example, about 50 ° 1, then about 7 parts by weight of crystals are removed if a solution is to be obtained which is particularly suitable for reuse in the absorption zone; at a degree of conversion of 20% this amount increases to about 15 parts by weight of crystals per part by weight of sulfur dioxide - and - at a theoretical degree of conversion of 100 l, this amount is about 3 to 3.5 parts by weight per part by weight of sulfur dioxide. The temperature drop in chamber 58 is determined by controlling the inlet temperature of the solution, the pressure in chamber 58, the residence time of the solution in chamber 58 (eg, generally about 15 minutes to 2 hours), the reflux ratio, and so on. Since the solution inlet temperatures are about 27 to 930C (about 80 to 2000F), usually about 54 to 710C (130 to 160 ° F) when processing power plant gases, and about 27 to 430C (80 to 110 ° F) when processing gases from sulfuric acid plants F) and the solution boils at a pressure of about 0.07 ata (1 psia) at about 400C (1040F) and at a pressure of about 0.035 ata (0.5 psia) at about 300C (850F) is generally a temperature drop of about 5.6 to 39 or 500C (10 to 70 or 900F), preferably about 17 to 28 or 390C (30 to 50 or 700F) is required to crystallize the desired amount of potassium pyrosulfite. The amount of water removed from the system in the blast chiller is preferably used to balance the water in the system by matching the amount of water removed in the blast chiller with the amount of water removed by the gas flow in the reactor 'Vassers relates. Although the 'wet' can easily be removed from the rapid cooling device, an energy supply is necessary for this purpose, whereas the energy is normally already present during the removal in the reactor. Thus, a particularly advantageous feature of the pre-sprinkling device 20 is that the pre-sprinkling is carried out with a liquid such as Nasser, while at the same time a significant temperature drop in the gas and a significant increase in the relative gas are avoided. On this;! Quietly, the gas in the absorption zone has an optimal temperature and an optimal relative humidity for the evaporation of the water from the system in a cheap and efficient way. If a gas stream with a low temperature and a high relative humidity is used, which has only a limited water absorption capacity, the system is nevertheless flexible, since the excess water can be removed by the rapid cooling device. The efficiency of the rapid cooling device in removing ',' lasser also enables advantageous control of the filtration conditions: the filter system used can be a simple rotary filter, and advantageous control of the temperature and the residence time of the solution can be achieved with ease, thereby increasing the size of the crystals for the purpose of better filterability at higher filter speeds and crystals with a higher purity, for example of 99 Å, can be obtained. Furthermore, the supersaturation is eliminated without nucleation, which means that there are no clogging problems that would arise when using a noise exchanger under the operating conditions of the present system. The cooled solution, or the crystal pulp, @, # l? R @ er @ on the flash vaporizer chamber 58 through line 7: .t in the crystallization container 60 passed. The residence time of the Solution in the crystallization container 60 is sufficient to remove crystals to produce with a size suitable for filtration, ie Crystals having a particle size greater than about 0.05 mm (300 mesh) up to about 1.7 mm (10 mesh). In general is a dwell time of about 5 minutes to 2 hours or more, preferably from about 10 to 45 minutes sufficient to le with the desired size. In the event of a dwell time of 45 minutes, crystals can be obtained, of which about 80 ö have a particle size between about 0.25 and 2 mm (10 to 60 mesh). Another important fact tor in the formation of crystals with this desired Size is the setting of the pH - '.', 'Ertes of the solution, the e.g. generally set to around 6.6 b5_9 7.4. The pH can be determined by a :; determining the density of the Reactor-directed reaction solution can be regulated by for example, the density regulator 69 in the line 71 is turned. The return line 80 and the pump 82 are designed to measure the temperature and residence time of the Fix the solution. The bottom of the flash chamber 58 is inclined, and the line 78 runs to the bottom 'es loading holder 60, causing clogging in the chamber 58 and the container 60 formed crystals is avoided. Located in the upper section of the rapid evaporation chamber 58 a defogging device 84, which in a similar 'Vei- se like the defogger 40 for removing the entrained droplets in the flow through line 66- the gas is constructed and acts similarly. The Kali.umnyrosulfi.t-Kr-i.stallbrei, which is in the crystallizing pit --- container 60 is obtained using the 'Pa @.: @: pe 1-? 6 dlii': `h the newspaper 88 is passed to a rotary drum vacuum filter 90. The drum filter contains a rotating drum 92 and a pan 94. The crystal slurry is introduced through the newspaper 88 into the pan 94 and sucked through the filter surface of the drum with the aid of a vacuum generated by the vacuum pump 0.6 inside the drum 92. The filtrate solution sucked off by the filter drum 92 is passed through the newspaper 98 to the filtrate container 100, in which it is collected and from which it is then pumped with the aid of the pump 104 through the newspaper 102 into the feed tank 106 for the absorber will.

The potassium pyrosulfite crystals retained on the filter surface of the drum 92 are removed by a scraper or scraper 108 and passed into a dissolving container 110. The filtration speed of the filter is kept as high as possible so that a clear filtrate is just obtained that leaves the filter through the newspaper 98. Filtration speeds of from about 4400 to 19,500, preferably from 7,300 to 14,500 kg of crystals per hour and m2 filter area (900 to 4000, preferably 1500 to 3000 lbs of crystals per hour and sq.ft. filter area) are usually achieved. The higher the filtration speed, the smaller the required filter area. The pocket size of the filter cloth can be important in order to obtain a clear filtrate. If, for example, crystals pass through the cloth, the pH of the filtrate drops, for example to about 6.3, which means that the return flow becomes worse due to the poorer absorption of SO2 due to the increased bisulfite content. That by the pump 96 on the drum filter. The vacuum generated is adjusted so that the vacuum on the drum 92 is worse (higher pressure) than the vacuum prevailing in the chamber 58. If a lower pressure was applied at this point in the system, the solution would cool even further and further potassium pyrosulfite would crystallize out in the drum 92, which would clog the system. The filter cloth used on the drum 92 is preferably a single filament cloth, for example nylon, that is chemically inert to the solution and the crystal slurry and the openings of which are generally 10 to 50 or 60 microns, preferably about 20 to 40 microns in size The crystals on the filter surface can advantageously be washed with the aid of a spray jet 112, for which purpose a branched stream of the 501o solution passed to the stripping column is preferably used, whereby the degree of purity of the crystals is improved 50% potassium bisulfite solution is saturated, virtually no crystals are dissolved and the purity of the crystals is only increased by displacing the mother liquor. If desired, a steaming spray or fan 114 can also be directed at the filter surface near the scraper 108 to clean the filter surface of the crystals that were not removed by the scraper 108.

The potassium pyrosulfite crystals can advantageously be in the presence of Water can be heated in order to decompose it to sulfur dioxide at a proportionate rate to promote low temperatures .. The water used can remove the remaining water from the mother liquor enclosed in the crystals, but also added water; it can be in any suitable form, e.g.

in liquid or vapor form, and it is used in such amounts that the decomposition of the potassium pyrosulfite is promoted with the release of sulfur dioxide. In general, these amounts are at least about 0.01% by weight, generally about 1 to 99% by weight, advantageously about 20-75% by weight, based on the potassium pyrosulfite and the water. the newspaper 88 turned into a rotary drum layuum filter 90 directs. The drum filter includes a rotating drum 92 and a pan 94. The crystal pulp is through the newspaper 88 inserted into the pan 94 and with the help of a through the Vacuum pump 96 created vacuum inside the drum 92 sucked through the filter surface of the drum. The one from the Filter drum 92 suctioned filtrate solution is through the Newspaper 98 passed to the filtrate container 100, in which it is collects and from which it then with the aid of the pump 104 through the newspaper 102_ in the Speiseb-Lsl: older 106 for the sorber pumped 1rjird. Those retained on the filter surface of the drum 92 Potassium pyrosulfite crystals are cleaned by a scraper or Scratches 108 removed and placed in a dissolving container 110 directs. The filtration speed of the filter will held as high as possible so that a clear film entered is obtained that the filter through the newspaper 98 leaves. Filtration speeds of about 4400 to 19,500, preferably from 7,300 to 14,500 kg Crystals per hour and m2 filter area (900 to 4000, preferably 1500 to 3000 lbs of crystals per hour and sq.ft. Filter area) reached. The higher the filtration speed speed, the smaller the required filter area. The pocket size of the filter cloth can be important to e: Obtain in clear filtrate. For example, go through crystals through the cloth, the pH of the filtrate drops, e.g. to about 6.3, whereby the return flow due to the poor Direct absorption of SO2 due to the increased bisulfite content gets worse. That by the pump 96 on the drum filter. generated vacuum is adjusted so that the vacuum at the Drum 92 worse (higher pressure) than that in the chamber mer 58 is the prevailing vacuum. When applying a lower Pressure at this point in the system. The solution would cool even further, and more potassium pyrosulfite would crystallize out in the drum 92, which would clog the system. The filter cloth used on drum 92 is preferably a monofilament cloth, such as nylon, that is chemically inert to the solution and crystal slurry and that has openings generally 10 to 50 or 60 microns, preferably about 20 to 40 microns. The crystals on the filter surface can advantageously be washed with the aid of a spray jet 112, for which purpose a branched stream of the 50% solution passed to the stripping column is preferably used, as a result of which the purity of the crystals is improved. Since the 50% potassium bisulfite solution is saturated, practically no crystals are dissolved and the purity of the crystals is only increased by displacing the mother liquor. If desired, a steamer or blower 114 can also be directed at the filter surface near the scraper 108 to clean the filter surface of crystals that were not removed by the scraper 108. _ The potassium pyrosulfite crystals can advantageously be heated in the presence of water in order to promote their decomposition to sulfur dioxide at relatively low temperatures. The water used can be the residual water of the mother liquor enclosed in the crystals, but also added water; it can be in any suitable form, e.g.

It will be in liquid or vapor form, and it will be in such amounts used that the decomposition of potassium pyrosulfite with the release of sulfur dioxide is promoted. In general, these amounts are at least about 0.01 wt. generally about 1 to 99% by weight, advantageously about 20-75% by weight, based on the potassium pyrosulphite and the 'Nasser. At about 20 Ü2, v.-ö Nasser moist crystals are obtained and at about 40 wt .- 'one obtains, for example, one Solution. In the solution, however, the potassium pyrosulfite is in the form of the Bi-CD it.

The crystals fed into the container 110 become lighter Subsequent processing dissolved in sufficient water. In general, at least so much water is added to form a pumpable pulp, for example about 60 to 70% solids - although as much if desired Can be added so that a solution is obtained. The relation between Solids and water in the dissolving tank 110 is expediently controlled with the aid of a density regulator 103 set. Generally it is about 35 to 55-4o, preferably about 40 to 50 '# o solids in the solution, which with the help of the pump 118 over .the newspaper 116 is removed from the dissolving container 110. The; Vasser is in the form of condensate from the cooler 70 via the line 72 or from the steam jet pumps 62 and 64 via the lines 74 and 76, respectively, are fed to the dissolving container 110. If desired, can fresh haters -for be initiated through line 120.

The potassium pyrosulfite in the presence or in contact with 'Yasser is heated so high that sulfur dioxide is released, in general Temperatures from about 38 to 107 ° C (100 to 225 ° F), preferably from about 66 to 1070C (150 to 225 ° F) under normal pressure.

The decomposition of the potassium pyrosulfite in contact with water can be carried out at normal pressure or at elevated pressure, for example at about 0 to 28 atmospheres (0 to 300 psia), generally from about 1 to 10 atmospheres (15 to 150 psia), although preferably at atmospheric pressure is being worked on. In a modification of this feature of the invention, one can operate at overpressure when the potassium pyrosulfite is in aqueous solution in order to increase the concentration of the solution at higher temperatures, for example above about 1100C (2300F) and up to about 1900C (3750F) An increase in the partial pressure of the sulfur dioxide in the potassium pyrosulfite and an improved release of sulfur dioxide are also achieved. paint amount of water used et, .- yes 5 to 50 or 70 wt. en For example, potassium bisulfite solution @ under one pressure heated from about 7 at (100 psia) to a temperature of about 1770C (3500F), the solubility of the pyrosulfite crystals is much greater, for example about 75 weight percent based on the crystals and water. At a nasty higher concentration the partial pressure of the sulfur dioxide is much higher than at lower concentrations, and the degree of conversion of the potassium pyrosulphite to potassium sulphite is also higher.

The use of water to improve the decomposition of potassium pyrosulfite is preferable to working under anhydrous conditions as there are no inert substances need to be used and therefore the cost of handling these substances fall away; furthermore, the sulfur dioxide "quietly obtained" has an essential lower temperature, and the degree of conversion of potassium pyrosulfite (bisulfite) too Sulfur dioxide is higher.

Since there is generally a small amount of sulfur trioxide in the exhaust gases containing sulfur dioxide, a small amount of potassium sulfate is formed which is removed periodically will. '' Furthermore, the acidic substance with the potassium sulfite with the formation of additional Potassium sulfate react, so it may be desirable an antioxidant, e.g. 3. organic compounds, such as hydroquinone, etc., to be added to the potassium sulfite solution. The potassium sulfate generally crystallizes with the pyro- sulfite and can by periodic dissolution of the pyro- sulfite crystals, which are more soluble in water than potassium sulfate, are separated. The dissolved pyrosulfite crystal After removing the solid potassium sulphate, oils can be poured into the Reaction zone are returned. Potassium sulfate is a Desired constituent of fertilizers. If desired, the process can be reduced to the production of potassium sulfate be made by omitting the inhibitor and the The amount of generated potassium sulfate is increased. The potassium bisulfite solution in the newspaper 16 is passed into the stripping zone 125, in which the solution is heated to a temperature sufficient to decompose the potassium bisulfite with the formation of sulfur dioxide and a potassium sulfite solution (e.g. to about 110 to 150 ° C). The decomposition is advantageously carried out in a multi-stage operation in order to increase the total conversion of potassium bisulfite into potassium sulfite and to reduce the amount of energy, ie the required steam, of the system. As indicated, stripping zone 125 contains two stripping columns 122 and 122 ', although three or more stages can be used if desired. The solution introduced through line 116 into column 122 is heated in a heater 138 with steam to a temperature sufficient to decompose the potassium bisulfite in the solution, generating a gas stream at the top, the sulfur dioxide and '' steam contains. This overhead withdrawn stream is removed by line 124 and directed to heater 138 'for second stripping column 122' to generate the energy required to decompose additional potassium bisulfite. The conversion of the potassium bisulfite to potassium sulfite in each individual stripping column is limited, since no further sulfur dioxide can be removed from the solution if the partial pressure of the sulfur dioxide in the vapors in the column is equal to the partial pressure of the sulfur dioxide in the solution, whatever how much energy is fed to the column. If several columns are used, fresh steam is generated in each column as a result of the removal of the water from the solution, which may be saturated with additional sulfur dioxide. whereby a further decomposition of the potassium bisulfite and an improved conversion are achieved. Furthermore, the energy or steam requirements of the system are reduced by recovering energy from the vapors generated in each stripper column by using those vapors to provide heat for the next column. After the heater 138 ', after which the water vapor in the line 124 is for the most part a condensed product, the product is passed through the line 12.6 into the separating device 128. The condensed water is removed from the bottom of the separator 128 through line 130 while the sulfur dioxide is removed as a gaseous product through line 131. The partially decomposed potassium bisulfite solution is removed from the column 122 through the line 134 and conveyed with the aid of the pump 136 to the column 122 ', in which additional potassium bisulfite is decomposed. The vapors occurring at the top of the column 122 'are removed through the line 124' and reach the container 128 'via the heat exchanger, ie the condenser 126'. The condensed water vapor is obtained from the separating container 128 'via the newspaper 130' removes, while the sulfur dioxide as a gaseous product is removed by newspaper 131 '. The soil fraction of the Stripper, which is now enriched in potassium sulfite Solution is, with the help of the pump 136 'by the Line 134 'into the addition container 106 for the absorber directed. Part of the scraper bottom fraction in the line tion 134: is used to maintain the appropriate temperature temperature (e.g. about 110 to 1500C) in der._Ahstreiferkolonne 122 I directed the heater 138: The one in the addition container 106 The potassium sulfite solution collected by the absorber is removed with the aid of the Pump 147 through line 142 into supply line 16 of the reactor 10 is pumped. The water in lines 130 and 130 'is directed to dissolving tank 110 and dissolves there the potassium pyrosulfite crystals. The first stage of the separation column is generally operated at overpressure and at a temperature sufficient to decompose the potassium bisulfite, e.g. up to about 14 at and about 3160C (200 psia and 600 ° F), but preferably below temperatures at which significant amounts of potassium sulfate are formed (e.g. at about 204 ° C) and below pressures of about 10 at (150 psia). Similarly, the separator in the first stage 122 is operated at a temperature of about 135 to 177 or 2040C (275 to 350 or 400 ° F) and a pressure of about 2.8 to 5.6 at (40 to 80 psia), preferably about 2.8 to 4.2 at (40 to 60 psia). These conditions are chosen in order to keep the steam requirement, ie the amount of steam required to generate the desired amount of sulfur dioxide, low. In general, it is desirable to keep the amount of steam at about 2 to 6, preferably about 2 to 4 parts by weight per part by weight of sulfur dioxide. Each subsequent stage can be operated at a pressure about 1.4 at (20 psia) lower than that of the previous stage and at appropriate decomposition temperatures. For example, the second stage separation column operates in a two stage system, generally at a pressure of from about 1.4 to 4.2 at (20 to 60 psia), preferably from about 1.4 to 2.8 at (20 to 40 psia), and at a temperature of about 120 to 1500C (250 to 300 ° F), preferably at a temperature of about 127 to 1380C (260 to 2800F).

If you want potassium sulfate, an undesirable by-product of the process, remove from the potassium bisulfite, so you can get some of the solution in the line 116 branch off through line 144, in which a centrifuge 146 or, if desired, a filter are arranged, with the help of which the potassium sulfate crystals through the Drain line 147 can be removed. Is a potassium bisulfite pulp for feeding the Stripping column 122 is used, the branching off and separation of the potassium sulfate in the newspaper 134 'or in the newspaper 142.

The system and its mode of operation are such that it is supported by the cyclical nature of the work steps, the temperature of the gases to be processed (e.g. the drop in temperature of the power plant gases in the evening) or the sulfur or solids content the gas is not adversely affected; so it's very flexible. So it can purify or all of any gas containing SO2, SO3 or particulate solids other types of impurities in any other gas compatible with the system and that does not adversely affect or adversely affect the system will, remove.

The embodiment according to FIG. 12 is practically the same as the embodiment according to FIG. 1, with the exception of the stripping zone 125 ', in which the potassium bisulfite is decomposed in the presence of an inert gas. In the system according to FIG. 12, the potassium bisulfite solution in the newspaper 116 'is passed into the stripping zone 125', in which the solution is heated to a temperature sufficient to decompose de.s-calcium bisulfite with the formation of sulfur dioxide and a potassium sulfite solution (e.g. about 110 to 150 ° C). The decomposition is advantageously effected by a multi-stage stripping, whereby the overall conversion of the potassium bisulfite to potassium sulfite is increased and the energy, i.e. the steam requirement of the system, is reduced: As shown, the stripping zone 125 'contains a stripping column 12211, although two, if desired or multiple stages can be used. The solution introduced through the newspaper 116 'into the column 122'# is heated in the heat exchanger 150 'with steam to a temperature which is generally below the boiling point at the operating pressure of the column, but which is sufficient to convert the potassium bisulfite in the solution to potassium sulfite and to decompose sulfur dioxide. The solution is introduced into column 12211 at the specified temperature. Although the bisulfite solution has decomposed, the sulfur dioxide can only be released when a driving force is present. Therefore, an inert gas, such as nitrogen, methane, argon, helium, etc., is introduced into the column 12211 through the line 130 ″ in order to drive the S02 out of the solution and preferably to saturate the inert gas with S02 If the sulfur dioxide in the vapors in the column is equal to the partial pressure of the sulfur dioxide in the solution, no further sulfur dioxide can be removed from the solution, no matter how much energy is added to the column. or steam demand of the system: by extracting energy from the vapors generated in each stripper column by using these vapors to generate heat for the next column. The inert gas containing SO 2 is passed through newspaper 12411 into heat exchanger 12611 in which the S02 is condensed and then passed into the separator 128 # '. The condensed S02 (which contains the water removed from the column 122'. ') t) is removed from the bottom of separator 12811 by newspaper 13811 while the inert gas is removed by newspaper 13211. With the help of the fan 130 ″ in the newspaper 13211, the inert gas is fed back into the column 12211. The partially decomposed potassium bisulfite solution is drawn off from the column 12211 through the newspaper 13411 and pumped with the aid of the pump 136 ″ to the addition container 106 ′ of the absorber. Temperatures of about 110 to 150 ° C (230 to 300 ° F) and pressures of up to about 14 at (200 psia) are commonly used in stripping column 12211. The solution in newspaper 116 ' is generally heated to as high a temperature as possible at which potassium sulfate is not yet formed and at which the solution does not yet boil. By supplying heat, the partial pressure of the SO2 in the solution is increased to the boiling point of the solution, creating a large pressure difference between the SO2 in the solution and in the inert gas, so that the inert gas can drive the SO2 out of the solution when it passes through the column 12211 passes through. In general, temperatures of about 110 to about 316 ° C, preferably less than about 2270 ° C (above which sulfate can form) and pressures of about 0 to 21 at (preferably from about 1 to 10 at) (0 to 300 psia, preferably 15 to 150 psia) is applied in the decomposition zone. The inert gas is passed through the column at a rate sufficient to drive the SO2 out of the solution; however, this speed is not so great that the solution is blown out of the column, ie it is, for example, about 0.45 to 6 m / sec. (1.5 to 20 FPS), preferably about 0.6 to 2.4 m / sec.

(2 to 8 ? Hp). Since a large part of the 'Hassers' is condensed in the column under these working conditions, little water vapor is removed with the inert gases, so that the regenerated potassium sulfite solution can be reused. The system described above and in FIGS. 1 and 2 for the production of SO2 was used for the treatment of exhaust gases from a coal-burning power station. To determine the temperature drop in the exhaust gas entering the pre-sprinkler device, a number of tests were carried out with changing ratios between sprinkler water and exhaust gas. In each experiment, the exhaust gas was at a flow rate of about 57 m3 / min. (approx. 2000 o.s. / min.) at a temperature of approx. 150 ° C into the pre-sprinkler device. The temperature and humidity of the gas immediately after it emerged from the impact surface were recorded.

The results are given in Table I. Example 1 Table II shows a typical example of the present process using the conditions and parameters set out in the discussion of Figures 1 and 2; the specific examples given in the drawings have been used and the table gives the corresponding compositions of the flows for the individual flow lines and the temperatures used. The exhaust gas had the following typical composition (in 1.10 l-%) sulfur dioxide 0.3%; Oxygen 3.4%; Water vapor 6.0 # i; Carbon dioxide 14.2%; Nitrogen 76.1% and sulfur tri-oxide 0.0003%. Virtually no potassium sulfate is formed. The vacuum chiller is operated at a pressure of about 0.07 ata (1 psia) and at a temperature of about 400C (1040F); the water is removed from the blast chiller at a rate of about 64 kg / hour (140 lbs / hour) and the pH of the solution in the crystallizer is about 7.0 to 7.2.

$ etegiel 2 The procedure is essentially as in Example 1, except that an aqueous cesium sulfite solution is used instead of potassium sulfite in order to form gesium bisulfite and to obtain the 302nd.

EXAMPLE 3 The procedure is essentially as in Example 1, except that an aqueous rubidium sulfite solution is used instead of potassium sulfite in order to produce rubidium bisulfite and extract SO 2.

FIG. 3 shows a section through a device according to the invention, as already described in connection with FIGS. 1 and 2, but the particulate solids or components soluble in liquids being removed separately in a gas stream. FIG. 3 shows the gas flowing through an electrostatic precipitator 200 to remove the larger particles; the pre-sprinkling stage 10 is used for the particulate solids in the. generally more difficult to remove are used. FIG. 3 shows a reaction vessel 100 with a cylindrical central section 101, in the lower quarter of which a circular gas supply line 105 leads. A tubular spray device for the liquid protrudes through the opening 106, approximately in the middle, into the central section. The reaction vessel has a conical bottom part 102 with a discharge line 26 for removing the liquid and particulate solids and an inverted conical top part 103 with an outlet for removing the purified gas. The circular support plate 15, which has a multitude of openings 107 (see FIG. 4), is in the zone xial attached to the tube 24 and on attached to the inner wall 108 of the central section 101. It carries a packed column 22, which is composed of three layers of ceramic Raschig rings. The packed column and the mounting plate form a gas-permeable impact surface 10. The spray nozzles 25 are preferably arranged at equal intervals on the inner®Teil 109 of the pipe 24 and are oriented in such a way that a steady stream of liquid (e.g. water) is sprayed against the impact surface 110.

Claims (1)

Patent claims 1. A method for purifying gases by '-' removing impurities in the form of soluble components and particulate suspended matter, characterized in that the gas is in an ascending flow in a sprinkling zone on an impact surface permeable to fluid media with a Filling of solid particles conducts, which form an incoherent surface to hold back the suspended solid matter entrained in the gas and thereby give the gas a speed which is sufficient to force the gas at least partially into and through the impact surface when it comes into contact with it through - .. to let penetrate, which one further along with the gas. Directs liquid to the impact surface at such a speed that the impact surface is wetted by the liquid but not penetrated, that the quantity of the liquid is chosen so that the components of the gas which are soluble in the liquid and the particulate suspended matter contained in the gas are absorbed the liquid will be transferred; and finally the liquid containing the impurities is recovered. Method according to Claim 1, characterized in that it is dKB Iman a sufficient amount of liquid ve344 ehdit, @ to form a process that contains the impurities , Fall off the impact surface and from the rubble zone must be removed before they evaporate, that the liquid is continuously directed to the underside of the impingement surface which is chemically inert to the liquid, and that the gas is at a temperature of up to about 427 ° C (800 ° F) with a such Gestfiwindigkeit to the impingement surface passes, is at least 60% by volume of one of the gas in the impact surface and penetrate through it, wherein the gas contains particles having a large front, about 0.5 to 50 microns. 3. The method according to claim 1 or 2, characterized in that the impact surface is filled with at least one layer of particles with maximum diameters between about 6.3 and 90 mm (0.25 to 3.5 inches) so that in the filling there is about 50 to g0% free space; that he. directs the liquid in the form of a spray from a distance of about 10 to 45 cm (4 to 18 inches) from below the impingement surface such that the liquid at the time of contact with the impingement surface has a velocity of about 0.6 to 4.5 m / sec. (2 to 15 FPS), and that the gas coming into contact with the liquid is directed against the impact surface at a sufficient distance from the spray jet in order to prevent the spray jet from being impaired, but the distance is again chosen to be so small that that excessive evaporation of the mist from the spray jet and falling of the droplets from the impact surface is prevented. 4. The method according to claim 1, 2 or 3, characterized in that the filling of the impact surface is composed of about 2 to 4 layers of particles so that it is about 38 to 140 mm (1.5 to 5; 5 inches) high with the particles between them forming a well-defined path for the gas flowing therethrough and weighing about 480 to 1200 g / liter (30 to 70 lbs / su.ft.); in that the spray of liquid is continuously dispensed and has droplets in the range of about 200 to 800 microns; that the gas flow at the time of contact with the impact surface has a speed of about 0.6 to 4.5 m / sec. (2 to 15 FPS) and one. Has a solids content of about 0.0023 to 140 g per m3 of gas (0.001 to 60 grains / cu.ft), and that the liquid flow at the time of contact with the impact surface has a speed of about 1.5 to 3.0 m / sec. (5 to 10 FPS). 5. The method according to any one of claims 1 to 4, characterized in that the solids content in the gas is about 1.2 to 70 g per m3 of gas (0.5 to 30 grains / cu.ft.Gas) and the components soluble in liquids are present in amounts from about 0.001 to 0.01 mole percent - that the gas is introduced at a temperature of up to about 4270C (about 800 ° F) from a distance of about 13 to 180 cm from the impact surface; the liquid is passed to the impact surface in an amount of about 0.67 to 67 cm 3 per m3 of gas per minute (0.01 to 1 GPM / 2000 CFM) and the filling of the impact surface from particles with maximum dimensions of about 25 to 38 mm (1 to 1.5 inches) and that these particles are rinsed intermittently with the aid of a rinsing liquid directed from above onto the impact surface. _ _-- 6. Process according to one of Claims 1 to 5, characterized in that the particulate suspended matter in the gas is fly ash and the compo-. nenten S03 and that water is used as the liquid. 7. The method according to one of claims 1 to 6, characterized in that the gas is subjected to a pre-dedusting for the purpose of removing larger amounts of particulate suspended matter, and that the water has a temperature of about 10 to 500C (50 to 1200F) and the gas a temperature from about 66 to 3160C (150 to 6000F) and a relative humidity of up to 10% and the particulate matter has a particle size of about 0.5 to 50 microns. .8th. Device for carrying out the method according to one of Claims 1 to 7, characterized by a horizontal impact surface which is permeable to fluid media and which contains a filling with at least one layer of individual, solid, non-porous particles, which in turn has an incoherent surface to hold back the from Gas entrained solids forms, further marked. net by devices for generating a spray jet directed essentially upwards from a sprinkling liquid for wetting the underside of the impact surface and through a gas line, with the help of which the gas is guided together with the liquid jet to the underside of the impact surface and is withdrawn after penetrating the impact surface . __- 9. Device according to claim 8, characterized in that the filling of the impact surface contains particles with a maximum diameter of about 6.3 to 90 mm and there is a free space of 50 to 90% between the particles. is. 10. Apparatus according to claim 8 or 9, characterized by a gas supply line which is arranged below the spray device for the liquid, and at a sufficient distance from the spray device, so that the spray jet is not impaired, but the distance is still so small is that excessive evaporation of the mist from the spray and falling of the liquid from the impact surface is avoided, and the gas stream flows together with the liquid to the impact surface, and penetrates into the impact surface and penetrates through this through a device for Collection of the liquid below the spray device, with the help of which the dripping liquid thrown back from the impact surface is collected and removed before the liquid can be evaporated @ and by flushing devices above the impact surface for the discontinuous flushing of its filling. 11. Device according to one of claims 8 to 10, characterized in that the spray device for the liquid is arranged about 10 to 45 cm below the impact surface, the individual particles in the filling of the. Impact surface are ceramic particles, the spray device consists of several elements, and the gas supply line is approximately 13 to 180 cm (5 to 70 inches) from the impact surface.