(19)
(11)EP 3 439 767 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
22.07.2020 Bulletin 2020/30

(21)Application number: 17715128.9

(22)Date of filing:  31.03.2017
(51)International Patent Classification (IPC): 
B01D 53/86(2006.01)
C01B 17/78(2006.01)
(86)International application number:
PCT/EP2017/057789
(87)International publication number:
WO 2017/174472 (12.10.2017 Gazette  2017/41)

(54)

SULFUR DIOXIDE REMOVAL FROM WASTE GAS

ENTFERNUNG VON SCHWEFELDIOXID AUS ABGAS

ÉLIMINATION DE DIOXYDE DE SOUFRE PRÉSENT DANS DES GAZ RÉSIDUAIRES


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Validation States:
MA

(30)Priority: 04.04.2016 LU 93012

(43)Date of publication of application:
13.02.2019 Bulletin 2019/07

(73)Proprietor: CPPE Carbon Process&Plant Engineering S.A.
1337 Luxembourg-Dommeldange (LU)

(72)Inventor:
  • STRICKROTH, Alain
    4408 Belvaux (LU)

(74)Representative: Office Freylinger 
P.O. Box 48
8001 Strassen
8001 Strassen (LU)


(56)References cited: : 
EP-A1- 2 260 940
JP-A- H11 236 207
EP-A2- 0 302 224
JP-B2- 3 562 551
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Technical field



    [0001] The present invention generally relates to sulfur dioxide removal from waste gas generated by chemical and metallurgical processes.

    Background Art



    [0002] A known method for sulfur dioxide removal from waste gas / flue gas is the Sulfacid® process. This process has been especially developed to meet the dual objectives of SO2 removal from waste gases generated by chemical and metallurgical processes and transformation into industrial grade sulfuric acid. It lends itself particularly well to applications where sulfuric acid can be directly used, for example titanium dioxide production or similar sulfuric acid based processes. Additionally, the fixed activated carbon bed is able to remove heavy metals (such as Hg and Cd) from the waste gas.

    [0003] Typical waste gas inlet parameters:
    SO2 content up to 1 vol.%
    Hg content 150 µg/Nm3 dry
    O2 content min. 7 vol.%
    Temperature 50 - 80°C
    Dust content < 30 mg/m3 STP (all data refers to dry gas)


    [0004] Typical clean gas outlet parameters:
    SO2 content ≤ 50 mg/Nm3 dry
    Hg content 25 µg/Nm3 dry


    [0005] The raw gas flows through an activated carbon catalyst fixed bed inside a reactor. The SO2 is converted to sulfuric acid by wet catalysis in the presence of oxygen and water. A water-saturated clean gas is discharged to atmosphere via a stack. The sulfuric acid collected in the pores and on the surface of the catalyst is intermittently washed out by spraying water over the catalyst. Clear industrial grade sulfuric acid of 10 to 50 wt.% strength is collected in a buffer tank. The conversion of sulfur dioxide to sulfuric acid on the catalyst works according to the following reaction equation:

            SO2 + ½ O2 + n H2O ⇒ H2SO4 · (n-1) H2O + heat



    [0006] The first Sulfacid® plant was started-up in 1968; now a few hundred plants are in operation worldwide.

    [0007] It has been found however that the process is less efficient for a higher SO2 concentration in the flue gas. It has been found that using more catalyst does not lead to higher removal of SO2.

    [0008] EP0 302 224 uses for the removal of SO2 in a gas a catalyst which is hydrophobized by means of hydrophobic polymer compounds such as polytetrafluoroethylene, polyisobutylene, polyethylene, polypropylene or polytrichlorfluorethylen, with a ratio of catalyst: hydrophobizing agent of 25:1 to 1:4.

    [0009] EP2 260 940 uses for the removal of SO2 in a gas a carbon based catalyst where iodine, bromine or compound thereof is added (ion exchanged or supported) and a water repellent treatment is applied to the carbon based catalyst to enhance the contact between the SO2 gas and the flue gas to be treated, containing SO2.

    [0010] JPH11 236207 and JP3562551B2 also use a carbon catalyst treated with a water repellent of catalyst to enhance the contact between the SO2 gas and the flue gas to be treated, containing SO2

    Technical problem



    [0011] It is an object of the present invention to enhance the performance of the SO2 removal from waste gases / flue gases generated by chemical and metallurgical processes and the transformation into industrial grade sulfuric acid.

    [0012] This object is achieved by a process as claimed in claim 1.

    General Description of the Invention



    [0013] To achieve this object, the present invention proposes a process wherein a gas containing SO2 and O2 is brought into contact with a mixture of from 95% vol. to 50% vol. of activated carbon catalyst and from 5% vol. to 50% vol. of an inert filler material; wherein the mixture is a mixture of separate, distinct particles of filler and separate, distinct particles of activated carbon catalyst; wherein the SO2 is converted to H2SO4 on the activated carbon catalyst and is then washed from the activated carbon catalyst to obtain a H2SO4 solution.

    [0014] In a preferred embodiment the mixture is soaked by water or an acid or alkaline aqueous solution.

    [0015] Alternatively the mixture is dry.

    [0016] The gas used in the present process is a waste gas generated by chemical and metallurgical processes.

    [0017] Surprisingly, the fact that the activated carbon catalyst is mixed with a filler material allows obtaining a more complete removal of SO2 from the gas.

    [0018] The activated carbon catalyst is preferably extruded and has a grain size of 0.80 - 130 mm. The activated carbon catalyst is preferably granulated and has a grain size: 0.30 to 4.75mm.

    [0019] In an embodiment the activated carbon catalyst is preferably a mixture of granulated and extruded catalyst.

    [0020] The carbon catalyst may be produced from brown and bituminous coals, fruit pits, coconut shells, lignite, peat, wood, sawdust / sawchip, petroleum coke, bone and paper mill waste (lignin), synthetic polymers like PVC, rayon, viscose, polyacrylonitrile or phenols.

    [0021] The carbon catalyst may be activated by :

    a physical treatment: heat, steam, oxygen, CO2, air

    a chemical treatment : impregnation with acid, strong base or salts (e.g. sulfuric, chlorhydric or phosphoric acid, potassium or sodium hydroxide, calcium or zinc chloride)

    a combination of both a physical and a chemical treatment.



    [0022] The activated carbon catalyst may have a specific surface area (BET): 400 to 1800 m2/g and an acid or alkaline pH.

    [0023] Preferably at least 5% vol 6% vol, 7% vol, 8% vol, 9% vol, 10% vol, 11% vol, 12% vol, 13% vol, 14% vol, 15% vol, 16% vol, 17% vol, 18% vol, 19% vol, 20% vol, 21% vol, 22% vol, 23% vol, 24% vol, 25% vol, 26% vol, 27% vol, 28% vol, 29% vol, or at least 30% vol of filler are used in the mixture of activated carbon catalyst and a filler material.

    [0024] Preferably at most 50% vol 49% vol, 48% vol, 47% vol, 46% vol, 45% vol, 44% vol, 43% vol, 42% vol, 41% vol, 40% vol, 39% vol, 38% vol, 37% vol, 36% vol, 35% vol, 34% vol, 33% vol, 32% vol, 31% vol, or at most 30% vol. of filler are used in the mixture of activated carbon catalyst and a filler material.

    [0025] In an embodiment, the filler material may comprise an active catalyst material (e.g. V, Fe, Zn, Si, Al2O3, ...).

    [0026] The filler is preferably chosen from fillers made of ceramic material, made of metal, fillers made of plastic material or mixtures thereof. Preferably, the filler material comprises plastic, metals, alumina, ceramic materials or mixture thereof.

    [0027] According to various embodiments, the filler material is a shape chosen among saddle shaped, ring shaped, ball shaped, torus shaped, prism shaped or irregular shaped.

    [0028] In particular, fillers made of ceramic material, having a free volume of 50-79% may be used:
    1. i. Novalox® Saddle : 12.7-76.2 mm
    2. ii. Berl saddle : 4-50 mm
    3. iii. Cylindrical ring : 5-200 mm
    4. iv. Pall® ring : 25-100 mm
    5. v. Transitional grid lining
    6. vi. Cylindrical ring with 1 bar or 1 cross : 80-200 mm
    7. vii. Grid block : 215*145*90 mm


    [0029] In particular, fillers made of metal, having a free volume of 95-98% may be used:
    1. i. Cylindrical ring . 15-50 mm
    2. ii. Pall® ring : 15-90 mm
    3. iii. VSP® : 25-50 mm
      1. i. Cylindrical ring . 15-50 mm
      2. ii. Pall® ring : 15-90 mm
      3. iii. VSP® : 25-50 mm
      4. iv. Top-Pak® : 15 mm
      5. v. Novalox®-M : 15-70 mm
      6. vi. Twin-Pak® : 10-15 mm
      7. vii. Interpak® : 10-20 mm


    [0030] In particular, fillers made of plastic, having a free volume of 87-97% may be used:
    1. i. Novalox® saddle : 12.7 - 50.8 mm
    2. ii. Pall® ring : 15-90 mm
    3. iii. VSP® : 25-90 mm
    4. iv. Igel® : 40 mm
    5. v. Netball® : 45-90 mm


    [0031] The filler material is thus made up of distinct, individual particles that are added to the activated carbon catalyst to improve, to enhance some properties of the mixtured material. The filler material particles generally have a mean particle size (based on the average largest dimension (by number) of the particle) of more than 4 mm. Usually their mean particle size (based on the average largest dimension (by number) of the particle) is less than 200 mm.

    [0032] In an embodiment, the mixture of activated carbon catalyst and a filler material contains no other solid ingredients than the activated carbon catalyst and the filler material. The total of these two ingredients makes thus 100%vol. of the mixture. It goes without saying that the mixture is a heterogeneous mixture since the components have a different particles sizes, different densities etc. The mixture comprises a mixture of separate, distinct particles of filler and separate, distinct particles of activated carbon catalyst. This makes it easy to separate the activated carbon catalyst from the filler when the activated carbon catalyst needs to be replaced.

    [0033] The SO2 removal is operated either as a so-called wet process or as a so-called dry process.

    [0034] The wet process involves continuous rinsing/washing of the catalyst bed as described in DE 2 235 123.

    [0035] In the dry process, the activated carbon catalyst is exposed to SO2 until the conversion rate of SO2 decreases, After this loading cycle, the supply of SO2 is switched off and the catalyst is subjected to rinsing/washing with water or an aqueous solution and the H2SO4 is washed out. The catalyst is then dried and can be reused after this regeneration-cycle. Such methods are described in US 3,486,852 or US 4,122,150.

    [0036] The present process can be used in an analogous way, either as a so-called wet process with a continuous rinsing/washing of the catalyst mixture or as a so-called dry process with a batch wise operation of a phase of loading the catalyst mixture with SO2 and a phase of washing/rinsing/drying of the catalyst mixture. In the "dry process", the catalyst mixture is usually rinsed during 2 hours with a total of about 100 litres of water per m3 of mixture, i.e. about 50 l/hour/m3 of mixture.During the wet process, the mixture of activated carbon catalyst and a filler material is preferably washed with water or an aqueous solution in an amount between 5 l/hour/m3 of mixture and 100 l/hour/m3 of mixture.

    [0037] The mixture of activated carbon catalyst and a filler material is preferably washed by intermittent spraying with water or an aqueous solution in counterflow to the gas.

    [0038] The process is operated preferably at a pressure from 0.9 to 1.1 atm and more preferably at atmospheric pressure.

    [0039] In the process as described the gas containing SO2 and O2 can be a waste gas generated by chemical and metallurgical processes. Its SO2 content is typically between 300 ppm and 200,000 ppm.

    [0040] The gas being brought into contact with the mixture of activated carbon catalyst and a filler material is usually at a temperature between 10°C and 150°C.

    [0041] The O2 content of the gas is as a rule between 2 and 21% vol.

    [0042] The H2SO4 content of the H2SO4 solution obtained is preferably between 5 and 50% vol. depending on the volume of water or aqueous solution used to rinse the mixture of activated carbon catalyst and a filler material.

    [0043] Any heavy metals (such as Hg and Cd) are also removed from the gas during the process.

    [0044] Any organic compounds are also removed from the gas in case of a dry process application.

    Brief Description of the Drawings



    [0045] Further details and advantages of the invention can be taken from the following detailed description of a possible embodiment of the invention on the basis of the accompanying FIG. 1. In the drawings:

    FIG. 1 is a schematic view of the arrangement;

    FIG. 2 is a graph showing the values measured during Test 1 of the SO2 content of the waste gases at the inlet and outlet of the reactor;

    FIG. 3 is a graph showing the values measured during Test 2 of the SO2 content of the waste gases at the inlet and outlet of the reactor;

    FIG. 4 is a graph showing the values measured during Test 3 of the SO2 content of the waste gases at the inlet and outlet of the reactor;

    FIG. 5 is a graph showing the values measured during Test 4 of the SO2 content of the waste gases at the inlet and outlet of the reactor;

    FIG. 6 is a graph showing the values measured during Test 5 of the SO2 content of the waste gases at the inlet and outlet of the reactor;

    FIG. 7 is a graph showing the values measured during Test 6 of the SO2 content of the waste gases at the inlet and outlet of the reactor.

    FIG. 8 is a graph showing the values measured during Test 7 and 8 of the SO2 loading capacity of an active carbon catalyst and of a mixture of an active carbon catalyst and a filler.

    FIG. 9 is a graph showing the values measured during Test 7 and 8 of the drying time of an active carbon catalyst and of a mixture of an active carbon catalyst and a filler.

    FIG. 10 is a graph showing the removal efficiency of an active carbon catalyst alone and different ways of mixing an active carbon catalyst with filler in relation to Test 9a, b, c and d,.

    FIG. 11 is a graph showing the removal efficiency of an active carbon catalyst mixed with different quantities of a first filler material in relation to Test 10,

    FIG. 12 is a graph showing the removal efficiency of an active carbon catalyst mixed with different quantities of a second filler material in relation to Test 11,

    FIG. 13 is a graph showing the removal efficiency of an active carbon catalyst mixed with 1/4 of different sized filler materials in relation to Test 12,

    FIG. 14 is a graph showing the removal efficiency of different types of active carbon catalyst mixed with 1/3 of filler materials in relation to Test 13,


    Description of Preferred Embodiments



    [0046] The test arrangement shown in FIG. 1 in order to illustrate the invention comprises a test reactor 10, to the lower part 12 of which a test gas is supplied and in the upper part 14 of which water is sprayed.

    [0047] For the purpose of these tests, instead of waste gas a test gas is used to simulate the waste gases. The test gas consists of ambient air which is used as is, at a temperature between 10-12°C and to which SO2 is subsequently added from a pressurized cylinder 18 via corresponding valve 22. A first measuring device 26 analyses the composition (SO2 content, O2 content), the temperature, the flow volume and the flow rate of the test gas.

    [0048] The test gas is then cooled to saturation temperature in a quench 28 by evaporation of water. The test gas is drawn via the quench 28 into the reactor 10 by a fan 30. A coalescer, a droplet separator or a mist collector at the outlet of the quench 28 collects any droplets that might be contained in the test gas as it exits from the quench.

    [0049] The test gas flows through the reactor 10 and through the activated carbon catalyst or the filling material or a combination of an activated carbon catalyst and filling material 32 arranged inside the test reactor 10. The test gas flows from the bottom to the top of the reactor 10 and is then examined once it is discharged from the test reactor 10 in a second measuring device 34 for the same parameters as in the first measuring device 26, i.e. composition (SO2 content, O2 content), the temperature, the flow volume and the flow rate, and is then released into the atmosphere.

    [0050] The water required in the process is fed from a storage container 36 via a metering device 38, where the flow is measured, and a pump 40 into the upper part 14 of the test reactor 10, where the water flows through the activated carbon catalyst or the filling material or a combination of activated carbon and filling material 32 in counterflow to the test gas.

    [0051] Alternatively however, the water required in the process can also be fed through the reactor in co-current flow with, i.e. in the same direction as, the test gas. The selection of a co-current or counterflow method depends for example on the local conditions.

    [0052] The water required for the quench 28 comes directly from the water supply and is circulated within the quench.

    [0053] The SO2 is catalytically converted into SO3 on the activated carbon catalyst, and is then converted into sulfuric acid if water is added.

    [0054] The filling material is randomly mixed with the activated carbon catalyst and the mixture is located above the sieve i.e. a metallic mesh sieve with mesh inferior to the particle size of the mixture of catalyst and filler (e.g. > 2 mm.

    [0055] The sulfuric acid formed is rinsed off from the activated carbon catalyst by intermittent spraying with water, as a function of the volume of the catalyst and of the SO2/SO3 concentration, in counterflow to the gas.

    [0056] The presence of filling material surprisingly improves the conversion efficiency during SO2 catalytic reaction and/or during spraying with water due to liquid/gas interaction. The presence of the filling material seems to enhance the liquid and gas flows as well as their repartition through the catalyst bed that allows a more uniform liquid and gas coverage of each catalyst grain and thus a higher SO3 to H2SO4 conversion. Indeed the regeneration of the activated carbon during dry process is quicker and more efficient leading to a shorter regeneration-cycle time.

    [0057] It has been found that there is a

    Good fluid distribution

    Low pressure drop in the reactor

    Less temperature gradient



    [0058] These main parameters may explain the better performance of the system.

    [0059] The filler material may optionally be impregnated as stated before.

    [0060] In the test reactor described above, spraying with water was carried out 1-4 times/hour using an amount of water of 12.5-125 l/hour/m3 of mixture. The water is collected in a container 42 in the lower part 12 of the test reactor 10 together with the aqueous sulfuric acid solution produced during the process. The acid content is determined by means of a measuring device 44. The sulfuric acid solution is then pumped off by a pump 46 and the flow volume is ascertained using a further measuring device 48.

    [0061] In the system described above, the sulfur dioxide of the waste gases is catalytically converted via SO3 on wet catalyst particles to form sulfuric acid. The method was tested successfully under the following conditions:
    • Water saturation of the waste gases before entry into the reactor by quenching.
    • SO2 content of the flue gases between 300 ppm and 6000 ppm.
    • Gas temperature between 10 and 12° C.
    • O2 content approximately 20% by volume.
    • Water saturation and eventually cooling of the waste gases by quenching.


    [0062] Tested catalysts were provided by CABOT NORIT Nederland B.V. of Postbus 105 NL-3800 AC Amersfoot and Jacobi Carbons GmbH Feldbergstrasse 21 D-60323 Frankfurt/Main under the names Norit®_RST-3, respectively JACOBI_ EcoSorb® VRX-Super. These catalysts are an extruded wood/charcoal based activated carbon catalysts with a particle size of about 3mm. The following general properties are guaranteed by the manufacturer: iodine number 900-1200 mg/g; inner surface (BET) 1000-1300 m2/g; bulk density 360-420kg/m3; ash content 6-7% by weight; pH alkaline; moisture (packed) 5% by weight.

    [0063] It must be noted that the active carbon catalysts do not contain:
    1. a. any iodine, bromine or a compound thereof,
    2. b. any water repellent
    3. c. any catalytically active metals such as Platinum, Palladium, Rhodium etc. or
    4. d. any organic/ catalytically active metal complexes based on metals such as Platinum, Palladium, Rhodium etc.


    [0064] The active carbon catalyst is not hydrophobized by means of hydrophobic polymer compounds such as polytetrafluoroethylene, polyisobutylene, polyethylene, polypropylene or polytrichlorfluorethylen.ln the tests, flue gas analyzers of a German company named Testo were used. The devices were calibrated by the manufacturer. In addition, the analysis data of these flue gas analyzers was confirmed by wet-chemical measurements carried out in parallel. The results of all measurements fell within the admissible deviation tolerances.

    [0065] The progression of the SO2 conversion by H2SO4 on the catalyst surface corresponds to the following total formula:

            SO2+½O2 +nH2O (catalytically)→H2SO4+(n-1)H2O



    [0066] Without wanting to be committed to a particular theory, it is assumed that:
    • O2 and SO2 migrate toward the active centers of the catalyst where they are converted into SO3.
    • SO3 migrates out from the active centers of the catalyst and forms H2SO4 with the aqueous covering around the catalyst core.
    • SO2 reacts with oxygen and water to form sulfuric acid in accordance with the reaction equation above.


    [0067] The filling material mixed with activated carbon catalyst enables an optimal liquid and gas interaction with catalyst active sites.

    [0068] Softened or demineralized water is used to wash out the catalyst.

    [0069] The specific level of SO2 saturation achieved in the pores of the catalyst in respect of the sulfuric acid formation occurs in the reactor once sufficient SO2 has been converted into SO3 and starts to form sulfuric acid.

    [0070] Such a condition is reached after approximately 20 to 100 operating hours depending on the approach adopted (amount of SO2/SO3 fed and corresponding water spraying rate). The percentage by weight of acid produced is independent of the duration - i.e. the time of contact between the gas and the catalyst. The SO2 to H2SO4 conversion is dependent on the SO2 to SO3 conversion efficiency and on the amount of water or aqueous solution used. For this reason, this process can produce solutions with different percentages by weight of sulfuric acids (H2SO4).
    Test 1: (Comparative Test) The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 2000 ppm
    max. 3000 ppm
    Gas temperature min. 10° C.
    max. 12° C.
    Relative Humidity of the gas   100 %
    O2 content   >20% by volume


    [0071] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the Norit®_RST-3 type.

    [0072] In a first phase the test system was run for approximately 50 hours with the addition of SO2 from gas cylinders, and in this instance between 2,000 and 3,000 ppm of SO2 were added. Overall, the reactor was charged with approximately 88 kg of SO2 (approximately 73 kg of SO2/m3 of catalyst bed). In accordance with this test, the addition of water at 15 l/hour was divided into 2 portions/hour (10.2 l/hour/m3 of catalyst bed). The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken every 30 seconds and are shown in graphs in FIG. 2. The first measurements shown in this case were taken after saturation of the catalyst, i.e. 50 hours after start-up of the reactor. The SO2 outlet concentration fluctuated repeatedly between 600 ppm and 900 ppm, with a SO2 removal efficiency of 66%. The test was carried out continuously over approximately 9 hours.
    Test 2 : The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 2000 ppm
    max. 3000 ppm
    Waste gas temperature min. 10° C.
    max. 12° C.
    % of relative humidity   100 %
    O2 content   >20% by volume


    [0073] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the JACOBI_ EcoSorb® VRX-Super type.

    [0074] Contrary to the test 1, the reactor was charged immediately when running with the addition of SO2 from gas cylinders, and in this instance between 2,000 and 3,000 ppm of SO2 were added. In accordance with this test, the addition of water at 15 l/hour was divided into 2 portions/hour (10.2 l/hour/m3 of catalyst bed). The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken every 30 seconds and are shown in graphs in FIG. 3. The first measurements shown in this case were taken directly after start-up of the reactor. The SO2 outlet concentration fluctuated repeatedly between 600 ppm and 900 ppm with a SO2 removal efficiency of 64%. The test was carried out continuously over approximately 6 hours.
    Test 3 : The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 2000 ppm
    max. 3000 ppm
    Waste gas temperature min. 10° C.
    max. 12° C.
    % of relative humidity   100 %
    O2 content   >20% by volume


    [0075] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the Norit®_RST-3 type modified by randomly mixing with 0.27 m3 of a ceramic filling material (Novalox ® saddle Acidur-Special-Stoneware supplied by Vereinigte Füllkörper-Fabriken).

    [0076] Like the test 2, the reactor was charged immediately when running with the addition of SO2 from gas cylinders, and in this instance between 2,000 and 3,000 ppm of SO2 were added. In accordance with this test, the addition of water at 15 l/hour was divided into 2 portions/hour (10.2 l/hour/m3 of catalyst bed). The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken every 30 seconds and are shown in graphs in FIG. 4. The first measurements shown in this case were taken directly after start-up of the reactor. The SO2 outlet concentration fluctuated repeatedly between 15 ppm and 95 ppm with a SO2 removal efficiency of 96%. The test was carried out continuously over approximately 7 hours.
    Test 4 : The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 2000 ppm
    max. 3000 ppm
    Waste gas temperature min. 10° C.
    max. 12° C.
    % of relative humidity   100 %
    O2 content   >20% by volume


    [0077] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the JACOBI_ EcoSorb® VRX-Super type modified by randomly mixing with 0.27 m3 of a ceramic filling material (Novalox ® saddle Acidur-Special-Stoneware supplied by Vereinigte Füllkörper-Fabriken).

    [0078] Like the test 2, the reactor was charged immediately when running with the addition of SO2 from gas cylinders, and in this instance between 2,000 and 3,000 ppm of SO2 were added. In accordance with this test, the addition of water at 15 l/hour was divided into 2 portions/hour (10.2 l/hour/m3 of catalyst bed). The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken every 30 seconds and are shown in graphs in FIG. 5. The first measurements shown in this case were taken directly after start-up of the reactor. The SO2 outlet concentration fluctuated repeatedly between 15 ppm and 92 ppm with a SO2 removal efficiency of 97%. The test was carried out continuously over approximately 7 hours.
    Test 5 : The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 2000 ppm
      max. 3000 ppm
    Waste gas temperature min. 10° C.
    max. 12° C.
    % of relative humidity   100 %
    O2 content >20% by volume  


    [0079] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the Norit®_RST-3 type modified by randomly mixing with 0.27 m3 of a ceramic filling material (Novalox ® saddle Acidur-Special-Stoneware supplied by Vereinigte Füllkörper-Fabriken).

    [0080] Like the test 2, the reactor was charged immediately when running with the addition of SO2 from gas cylinders, and in this instance between 2,000 and 3,000 ppm of SO2 were added. In accordance with this test, the addition of water at 71 l/hour was divided into 2 portions/hour (48.3 l/hour/m3 of catalyst bed). The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken every 30 seconds and are shown in graphs in FIG. 6. The first measurements shown in this case were taken directly after start-up of the reactor. The SO2 outlet concentration fluctuated repeatedly between 9 ppm and 43 ppm, with a SO2 removal efficiency of 98%. The test was carried out continuously over approximately 4 hours.
    Test 6 : The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 2000 ppm
    max. 3000 ppm
    Waste gas temperature min. 10° C.
      max. 12° C.
    % of relative humidity   100 %
    O2 content >20% by volume  


    [0081] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the Norit®_RST-3 type modified by randomly mixing with 0.27 m3 of a plastic filling material (Pall®-V-ring supplied by Vereinigte Füllkörper-Fabriken).

    [0082] Like the test 2, the reactor was charged immediately when running with the addition of SO2 from gas cylinders, and in this instance between 2,000 and 3,000 ppm of SO2 were added. In accordance with this test, the addition of water at 15 l/hour was divided into 2 portions/hour (10.2 l/hour/m3 of catalyst bed). The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken every hours and are shown in graphs in FIG. 7. The first measurements shown in this case were taken directly after start-up of the reactor. The SO2 concentration fluctuated repeatedly between 90 ppm and 160 ppm, with a SO2 removal efficiency of 95%. The test was carried out continuously over approximately 30 hours.
    Test 7 : The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 18000 ppm
    max. 22000 ppm
    Waste gas temperature min. 10° C.
    max. 12° C.
    % of relative humidity   <10 %
    O2 content >18% by volume  


    [0083] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the Norit®_RST-3 type.

    [0084] The quench was switched off during this test and dried activated carbon is used.

    [0085] Like the test 2, the reactor was charged immediately when running with the addition of SO2 from gas cylinders, and in this instance between 18,000 and 22,000 ppm of SO2 were added without addition of water during the SO2-loading phase. The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken each minute. The SO2 concentration fluctuated repeatedly between 18000 ppm and 22000 ppm, with a SO2 removal efficiency of more than 99%. The test was carried out over approximately 106 minutes until SO2 outlet was higher than 100 ppm. The SO2-loading efficiency was 23 kg of SO2 per cubic meter of activated carbon. After this SO2-loading step, the activated carbon was washed continuously for two hours through addition of water at 50 l/hour. In a next step, ambient air, heated at 80 °C, is pulled through the catalytic bed and the activated carbon is dried after a time period of 74 hours.
    Test 8 : The tests were carried out under the following conditions:
    Raw gas volume flow min. 200 m3/h
    max. 300 m3/h
    SO2 content (inlet) min. 18000 ppm
    max. 22000 ppm
    Waste gas temperature min. 10° C.
    max. 12° C.
    % of relative humidity   <10 %
    O2 content >18% by volume  


    [0086] The reactor is made of inert glass fiber reinforced plastics material, has a volume of approximately 2 m3 and is filled with 1.2 m3 of an activated carbon catalyst of the Norit®_RST-3 type modified by randomly mixing with 0.27 m3 of a ceramic filling material (Novalox ® saddle Acidur-Special-Stoneware supplied by Vereinigte Füllkörper-Fabriken).

    [0087] The quench was switched off during this test and dried activated carbon is used.

    [0088] Like the test 2, the reactor was charged immediately when running with the addition of SO2 from gas cylinders, and in this instance between 18,000 and 22,000 ppm of SO2 were added without addition of water during the SO2-loading phase. The SO2 content of the waste gases was measured at the inlet and at the outlet of the reactor, as illustrated in FIG. 1. The measurements were taken each minute. The SO2 concentration fluctuated repeatedly between 18000 ppm and 22000 ppm, with a SO2 removal efficiency of more than 99%. The test was carried out over approximately 117 minutes until SO2 outlet was higher than 100 ppm.. The SO2-loading efficiency was 26 kg of SO2 per cubic meter of activated carbon. After this SO2-loading step, the activated carbon was washed continuously for two hours through addition of water at 50 l/hour. In a next step, ambient air, heated at 80 °C, is pulled through the catalytic bed and the activated carbon is dried after a time period of 63 hours.

    [0089] All the above tests have been carried out with 1.2 m3 of catalyst (activated carbon). In the tests carried out with addition of filler (whatever its shape): 0.27 m3 of filler were added to the initial 1.2m3 of catalyst.



    [0090] A positive effect of the filler can be measured between 5%vol filler and 50% filler, the remaining being activated carbon catalyst.

    [0091] The surprising effect is that the removal of SO2 is more efficient when the catalyst is mixed with fillers than the catalyst alone since more SO2 is converted with the same amount of catalyst as shown in Fig. 10.

    [0092] In addition in case of dry process conditions, the SO2-loading capacity of activated carbon is higher and the regeneration cycle is shorter in case the activated carbon is mixed with fillers as shown in Fig. 8 and in Fig.9.

    [0093] In the tests conducted it was found that ceramic filler material having a saddle shape seem to be the most efficient. Saddle shape means in the context of the present invention: shaped in the form of a horse's saddle, a shape that is bent down at the sides so as to give the upper part a rounded form, respectively an object having the form of an anticlinal fold.

    Test 9 - Figure 10: Effect of Bed Design



    [0094] In these tests different types of mixing and bed designs were tested and compared to each other in a reactor as depicted on Fig. 1.

    [0095] The conditions were as follows: Test 9a

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Activated carbon catalyst: 1.2 m3 of extruded activated carbon catalyst with particle size 2-4 mm

    Filler material: 0.27 m3 of 38.1 mm wide ceramic saddle filling material

    Mixing method: random mixture: most efficient with 90-100% SO2 cf. removal efficiency as shown on Fig. 10 - left hand side


    Comparative Example Test 9b - Figure 10



    [0096] The conditions were as follows:

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Single activated carbon catalyst bed: 55-65% SO2 removal efficiency as shown on Fig. 10 - second from the left.


    Comparative Example Test 9c - Figure 10



    [0097] The conditions were as follows:

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Activated carbon catalyst: 1.2 m3 of extruded activated carbon catalyst with particle size 2-4 mm

    Filler material: 0.27 m3 of 38.1mm wide ceramic saddle filling material

    Two activated carbon catalyst beds (0.5 m3 and 0.7 m3 respectively) separated by a layer of 0.27 m3 of filling material : less efficient with 50-65% SO2 removal efficiency as shown on Fig. 10 - third from the left.


    Comparative Example Test 9d - Figure 10



    [0098] The conditions were as follows:

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Activated carbon catalyst: 1.2 m3 of extruded activated carbon catalyst with particle size 2-4 mm Filler material: 0.27 m3 of 38mm wide ceramic saddle filling material

    Multi layers design: activated carbon catalyst/filler material layers (0.3 m3 and 0.054 m3 respectively) was much less efficient with 70-80% SO2 removal efficiency as shown on Fig. 10 - right hand side


    Test 10 - Figure 11 : Effect of filler material / activated carbon volume ratio



    [0099] The conditions were as follows:

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Activated carbon catalyst: extruded activated carbon with particle size 2-4 mm

    Filler material: 38mm wide ceramic saddle filling material

    Mixing method: random mixture with different ratio in volume (Filler material/extruded activated carbon catalyst):

    1/20: 5 vol% filler material and 95 vol% activated carbon catalyst

    1/10: 9 vol% filler material and 91 vol% activated carbon catalyst

    1/5: 17 vol% filler material and 83 vol% activated carbon catalyst

    1/4: 20 vol% filler material and 80 vol% activated carbon catalyst

    1/3: 25 vol% filler material and 75 vol% activated carbon catalyst

    This test shows the highest efficiency with 99% SO2 removal when operating with 20 vol% filler material and 80 vol% activated carbon catalyst (ratio 1/4) as shown on Fig. 11.


    Test 11 - Figure 12: Effect of filler material / activated carbon volume ratio



    [0100] The conditions were as follows:

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Activated carbon catalyst: extruded activated carbon with particle size 2-4 mm

    Filler material: 50mm wide plastic pall ring filling material

    Mixing method: random mixture with different ratio in volume (Filler material/extruded activated carbon catalyst):

    1/20: 5 vol% filler material and 95 vol% activated carbon catalyst

    1/10: 9 vol% filler material and 91 vol% activated carbon catalyst

    1/5: 17 vol% filler material and 83 vol% activated carbon catalyst

    1/4: 20 vol% filler material and 80 vol% activated carbon catalyst

    1/3: 25 vol% filler material and 75 vol% activated carbon catalyst

    Highest efficiency 82% SO2 removal when operating with 20 vol% filler material and 80 vol% activated carbon (ratio 1/4) as shown on Fig. 12.


    Test 11 - Figure 13: Effect of filler size



    [0101] The conditions were as follows:

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Activated carbon catalyst: extruded activated carbon catalyst with particle size 2-4 mm

    Filler material: saddle filling material with different size from 12.7 (normalized size 1) to 76.2 mm (normalized size 6)

    Mixing method: random mixture with 20 vol% filler material and 80 vol% activated carbon catalyst (ratio 1/4)

    Higher efficiency with 88-99% SO2 removal when operating with between 38,1 mm (normalized size 3) and 63.5 mm (normalized size 5) saddle filling material as shown on Fig. 13


    Test 12 - Figure 14: Effect of filler particle size



    [0102] The conditions were as follows:

    Gas flow: 200-300 m3/h

    Gas temperature: starting from 10°C

    Gas flow inlet: 2000-3000 ppm

    Activated carbon catalyst:bead, extruded or granulated activated carbon catalyst

    Filler material: 38,1 mm wide ceramic saddle filling material

    Mixing method: random mixture with 20 vol% filler material and 80 vol% activated carbon catalyst (ratio 1/4)

    Higher efficiency with 99% SO2 removal when operating with extruded activated carbon catalyst as shown on Fig. 14.



    [0103] Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

    [0104] All the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar.


    Claims

    1. A process wherein a gas, containing SO2 and O2 is brought in contact with a mixture of from 95% vol. to 50% vol. of activated carbon catalyst and from 5% vol. to 50% vol. of an inert filler material; wherein the SO2 is converted to H2SO4 on the activated carbon catalyst and is then washed from the activated carbon catalyst to obtain a H2SO4 solution.
     
    2. The process as claimed in claim 1, wherein the filler material is between 10% vol. and 30% vol. of the mixture of activated carbon catalyst and a filler material.
     
    3. The process as claimed in claim 1 or 2, wherein the mixture contains no other solid ingredients than the activated carbon catalyst and the filler material.
     
    4. The process as claimed in any one of claims 1 to 3, wherein the activated carbon catalyst is chosen from impregnated (like Fe, S, OH,...) or activated carbon catalysts from suppliers like Jacobi, Cabot Norit, Chemviron, Desotec, Carbotech and ATEC.
     
    5. The process as claimed in any one of the preceding claims, wherein the filler is chosen from fillers made of ceramic material, made of metal, fillers made of plastic material or mixtures thereof.
     
    6. The process as claimed in any one of the preceding claims, wherein the filler material is a shape chosen among saddle shaped, ring shaped, ball shaped, torus shaped, prism shaped or irregular shaped.
     
    7. The process as claimed in any one of the preceding claims, wherein the mixture is in a fixed bed.
     
    8. The process as claimed in any one of the preceding claims, wherein the mixture is washed with water or an aqueous solution in an amount between 5 l/hour/m3 of catalyst and 100 l/hour/m3 of mixture.
     
    9. The process as claimed in any one of the preceding claims, wherein the mixture is washed by intermittent spraying with water or an aqueous solution in counterflow to the gas.
     
    10. The process as claimed in any one of the preceding claims, wherein the process is operated at a pressure from 0.9 to 1.1 atm, preferably at atmospheric pressure.
     
    11. The process as claimed in any one of the preceding claims, wherein the water saturated gas containing SO2 and O2 is a waste gas generated by chemical and metallurgical processes.
     
    12. The process as claimed in any one of the preceding claims wherein the SO2 content of the gas is between 300 ppm and 200,000 ppm.
     
    13. The process as claimed in any one of the preceding claims, the gas being brought into contact with the mixture has a temperature of between 10 and 150°C.
     
    14. The process as claimed in any one of the preceding claims, wherein the O2 content of the gas is between 2 and 21 % vol.
     
    15. The process as claimed in any one of the preceding claims, wherein the H2SO4 content of the H2SO4 solution is between 5 and 50% vol.
     
    16. The process as claimed in any one of the preceding claims, wherein heavy metals (such as Hg and Cd) are removed from the gas..
     
    17. The process as claimed in any one of the preceding claims, wherein organic contaminants are removed from the gas.
     


    Ansprüche

    1. Verfahren, wobei ein Gas, das SO2 und O2 enthält, in Kontakt mit einem Gemisch von 95 Vol.-% bis 50 Vol.-% Aktivkohlekatalysator und von 5 Vol.-% bis 50 Vol.-% eines inerten Füllstoffmaterials gebracht wird; wobei das Gemisch ein Gemisch von separaten, individuellen Füllstoffpartikeln und separaten, individuellen Aktivkohlekatalysatorpartikeln ist; wobei das SO2 auf dem Aktivkohlekatalysator in H2SO4 umgewandelt wird und dann von dem Aktivkohlekatalysator gewaschen wird, um eine H2SO4-Lösung zu erhalten.
     
    2. Verfahren nach Anspruch 1, wobei das Füllstoffmaterial zwischen 10 Vol.-% und 30 Vol.-% des Gemischs von Aktivkohlekatalysator und einem Füllstoffmaterial ausmacht.
     
    3. Verfahren nach Anspruch 1 oder 2, wobei das Gemisch keine anderen festen Bestandteile als den Aktivkohlekatalysator und das Füllstoffmaterial enthält.
     
    4. Verfahren nach einem der Ansprüche 1 bis 3, wobei der Aktivkohlekatalysator aus imprägnierten (wie Fe, S, OH, ...) oder Aktivkohlekatalysatoren von Anbietern wie Jacobi, Cabot Norit, Chemviron, Desotec, Carbotech und ATEC ausgewählt ist.
     
    5. Verfahren nach einem der vorhergehenden Ansprüche, wobei der Füllstoff aus Füllstoffen, die aus Keramikwerkstoff hergestellt sind, aus Metall hergestellt sind, Füllstoffen, die aus Kunststoffmaterial hergestellt sind, oder Gemischen davon ausgewählt ist.
     
    6. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Füllstoffmaterial eine Form aufweist, die aus einer Sattelform, Ringform, Kugelform, Torusform, Prismaform oder unregelmäßigen Form ausgewählt ist.
     
    7. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Gemisch in einem Festbett ist.
     
    8. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Gemisch mit Wasser oder einer wässrigen Lösung in einer Menge zwischen 5 L/Stunde/m3 Katalysator und 100 L/Stunde/m3 Gemisch gewaschen wird.
     
    9. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Gemisch durch intermittierendes Besprühen mit Wasser oder einer wässrigen Lösung im Gegenstrom zu dem Gas gewaschen wird.
     
    10. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Verfahren bei einem Druck von 0,9 bis 1,1 atm, vorzugsweise bei atmosphärischem Druck betrieben wird.
     
    11. Verfahren nach einem der vorhergehenden Ansprüche, wobei das wassergesättigte Gas, das SO2 und O2 enthält, ein Abgas ist, das von chemischen und metallurgischen Verfahren erzeugt wird.
     
    12. Verfahren nach einem der vorhergehenden Ansprüche, wobei der SO2-Gehalt des Gases zwischen 300 ppm und 200.000 ppm liegt.
     
    13. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Gas, das mit dem Gemisch in Kontakt gebracht wird, eine Temperatur zwischen 10 und 150 °C aufweist.
     
    14. Verfahren nach einem der vorhergehenden Ansprüche, wobei der O2-Gehalt des Gases zwischen 2 und 21 Vol.-% liegt.
     
    15. Verfahren nach einem der vorhergehenden Ansprüche, wobei der H2SO4-Gehalt der H2SO4-Lösung zwischen 5 und 50 Vol.-% liegt.
     
    16. Verfahren nach einem der vorhergehenden Ansprüche, wobei Schwermetalle (wie Hg und Cd) aus dem Gas entfernt werden.
     
    17. Verfahren nach einem der vorhergehenden Ansprüche, wobei organische Verunreinigungen aus dem Gas entfernt werden.
     


    Revendications

    1. Procédé dans lequel un gaz, contenant du SO2 et du O2, est mis en contact avec un mélange de 95 % en volume à 50 % en volume d'un catalyseur à base de charbon activé et de 5 % en volume à 50 % en volume d'une matière de charge inerte ; dans lequel le mélange représente un mélange de particules distinctes séparées d'une matière de charge et de particules distinctes séparées d'un catalyseur à base de charbon activé ; dans lequel le SO2 est transformé en H2SO4 sur le catalyseur à base de charbon activé et est ensuite éliminé par lavage du catalyseur à base de charbon activé pour obtenir une solution de H2SO4.
     
    2. Procédé selon la revendication 1, dans lequel la matière de charge représente entre 10 % en volume et 30 % en volume du mélange du catalyseur à base de charbon activé et d'une matière de charge.
     
    3. Procédé selon la revendication 1 ou 2, dans lequel le mélange ne contient pas d'autres ingrédients solides en dehors du catalyseur à base de charbon activé et de la matière de charge.
     
    4. Procédé selon l'une quelconque des revendications 1 à 3, dans lequel le catalyseur à base de charbon activé est choisi parmi des catalyseurs imprégnés (tels que Fe, S, OH, ...) ou de charbon activé disponibles auprès de fournisseurs tels que Jacobi, Cabot Norit, Chemviron, Desotec, Carbotech et ATEC.
     
    5. Procédé selon l'une quelconque des revendications précédentes, dans lequel la matière de charge est choisie parmi des matières de charge en une matière céramique, en métal, des matières de charge en une matière plastique, ou leurs mélanges.
     
    6. Procédé selon l'une quelconque des revendications précédentes, dans lequel la matière de charge possède une configuration choisie parmi une configuration en forme de selle, une configuration de forme annulaire, une configuration de forme sphérique, une configuration de forme torique, une configuration de forme prismatique ou une configuration de forme irrégulière.
     
    7. Procédé selon l'une quelconque des revendications précédentes, dans lequel le mélange est disposé dans un lit fixe.
     
    8. Procédé selon l'une quelconque des revendications précédentes, dans lequel le mélange est lavé avec de l'eau ou avec une solution aqueuse en une quantité entre 5 l/heure/m3 de catalyseur et 100 l/heure/m3 de mélange.
     
    9. Procédé selon l'une quelconque des revendications précédentes, dans lequel le mélange est lavé via une pulvérisation intermittente avec de l'eau ou avec une solution aqueuse à contre-courant par rapport au gaz.
     
    10. Procédé selon l'une quelconque des revendications précédentes, dans lequel le procédé est mis en oeuvre sous une pression de 0,9 à 1,1 atm., de préférence sous pression atmosphérique.
     
    11. Procédé selon l'une quelconque des revendications précédentes, dans lequel le gaz saturé en eau contenant du SO2 et du O2 est un gaz résiduaire généré par des processus chimiques et métallurgiques.
     
    12. Procédé selon l'une quelconque des revendications précédentes, dans lequel la teneur du gaz en SO2 se situe entre 300 ppm et 200.000 ppm.
     
    13. Procédé selon l'une quelconque des revendications précédentes, dans lequel le gaz qui est mis en contact avec le mélange possède une température entre 10 et 150 °C.
     
    14. Procédé selon l'une quelconque des revendications précédentes, dans lequel la teneur du gaz en O2 se situe entre 2 et 21 % en volume.
     
    15. Procédé selon l'une quelconque des revendications précédentes, dans lequel la teneur en H2SO4 de la solution de H2SO4 se situe entre 5 et 50 % en volume.
     
    16. Procédé selon l'une quelconque des revendications précédentes, dans lequel des métaux lourds (tels que Hg et Cd) sont éliminés du gaz.
     
    17. Procédé selon l'une quelconque des revendications précédentes, dans lequel des contaminants organiques sont éliminés du gaz.
     




    Drawing















































    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description