WO2019134752A1 - Procédé et installation d'épuration de gaz contenant du dioxyde de soufre - Google Patents

Procédé et installation d'épuration de gaz contenant du dioxyde de soufre Download PDF

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Publication number
WO2019134752A1
WO2019134752A1 PCT/EP2018/050318 EP2018050318W WO2019134752A1 WO 2019134752 A1 WO2019134752 A1 WO 2019134752A1 EP 2018050318 W EP2018050318 W EP 2018050318W WO 2019134752 A1 WO2019134752 A1 WO 2019134752A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas
tower
process according
packed bed
fluoride
Prior art date
Application number
PCT/EP2018/050318
Other languages
English (en)
Inventor
Karl-Heinz Daum
Klaus Hasselwander
Ullrich Voigt
Original Assignee
Outotec (Finland) Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Outotec (Finland) Oy filed Critical Outotec (Finland) Oy
Priority to PCT/EP2018/050318 priority Critical patent/WO2019134752A1/fr
Priority to CN201890001472.0U priority patent/CN213492919U/zh
Publication of WO2019134752A1 publication Critical patent/WO2019134752A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/68—Halogens or halogen compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/32—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by electrical effects other than those provided for in group B01D61/00
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/75—Multi-step processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/48—Sulfur dioxide; Sulfurous acid
    • C01B17/50—Preparation of sulfur dioxide
    • C01B17/56—Separation; Purification
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/20—Halogens or halogen compounds
    • B01D2257/202—Single element halogens
    • B01D2257/2027—Fluorine

Definitions

  • the invention relates to a process and its relating plant for cleaning S0 2 C ontain- ing gas, wherein a process gas stream containing at least 1.0 wt.-% SO 2 is quenched before it passes a packed bed tower and is then fed into at least on electrostatic precipitator, whereby condensate from the electrostatic precipitator is guided into a liquid effluent treatment plant.
  • S0 2 -containing process gas originating from metallurgical plants treating or smelting sulfidic non-ferrous ores are commonly processed in a hot and wet gas cleaning plant consisting of a multitude of process steps, prior to being routed to further processing and conversion to sulfuric acid.
  • SO 3 sulfur trioxide
  • the use of e.g. dust settling chambers, cyclones and/or hot electrostatic precipitators is typical for solids removal purposes.
  • some metal compounds, e.g. AS2O3, as well as the H 2 S0 4 are usually in gaseous form and can thus not be removed by such equipment.
  • halides such as chlorides and fluorides will also pass through this equipment.
  • the hot gases are quenched with weak acid / water and cooled down adiabatically. Except for the halides, the impurities will con- dense or sublimate and form sub-micron particles which must be removed from the gas by various unit operations.
  • Halides will usually not condense but remain gaseous, particularly fluorides, and thus must be removed by absorption in suitable aqueous solutions. While ab- sorbed chlorides do typically not express a noticeable vapor pressure, and are hence relatively easy to separate from the gas, absorbed fluorides dissolved in aqueous solution, on the contrary can exert a significant vapor pressure which limits its efficient removal from the gas.
  • the gas cleaning and sulfuric acid plant leads to high investment and maintenance costs, but are indispensable based on the need for environmental protection and to avoid pollution.
  • the sulfuric acid is a non-desired by-product which cannot be stored in large quantities and thus must be readily sold or give-away. While good quality acid can be marketed for a reasonable price, lower quality acid, i.e. containing higher amounts of impuri- ties, does attract a significant lower price and is of limited use for e.g. fertilizer production.
  • the gas cleaning section must be substantially more efficient.
  • Sub-micron particles containing substances like arsenic or selenium, H 2 S0 4 - mist or metal compounds, can be separated well in scrubbers operating at ele- vated pressure drop.
  • Downstream wet electrostatic precipitators (wet Electro- static precipitators) must remove the remainder of those substances from the gas to a degree suitable for the downstream processing of the gas at the sulfuric acid plant.
  • H 2 S0 4 , HCI and H 2 F 2 are competing reaction partners and dissolved halides can become less stable (less soluble) at increased H 2 S0 4 concentration. Complete absorp- tion of halides is thus getting increasingly difficult with higher H 2 S0 4 , concentra- tion of the liquid.
  • Chlorides are not as critical and usually separated at a gas cooling tower which is required to reduce and meet the desired residual moisture content of the gas.
  • the characteristics of the fluorides require specific and additional measures, subject to the level of the fluorides concentration in the incoming gas.
  • This invention suggests several highly efficient methods for the removal of fluo- rides from metallurgical gases, while minimizing the use of fresh additional process water and hence also minimizing the amount of weak/wash acid dis- charged from the wet gas cleaning section for downstream liquid effluent treat- ment.
  • a standard specification of technical grade sulfuric acid calls for less than 1 ppm of F, which correlates to less than 1 mg of F per Nm 3 of gas leaving the wet gas cleaning section.
  • Premium quality acid requires typically less than 0.2 ppm F.
  • Fluorides slipping into the acid plant do also attack the glass-fibers of the candle filters at drying and absorption towers. It does also potentially destroy the silica carrier of the V 2 0 5 catalyst used for the oxidation of SO 2 to SO 3 . So, there are plenty of reasons to control the F-content of the gas leaving the wet gas cleaning section towards the sulfuric acid plant.
  • Such a process for cleaning SO2 is directed to a cleaning of a process gas stream containing at least 1 .0 wt.-% SO2.
  • the process gas is quenched before it passes a packed bed tower for a further cooling to typically 40°C.
  • the process gas stream is fed into at least one electrostatic precipita tor, whereby condensate from the electrostatic precipitator is guided into a water treatment plant.
  • This invention is characterized by the separate withdrawal of the condensate of the wet electrostatic precipitators, which contains most of the sulfuric acid enter- ing the wet gas cleaning section.
  • the absence of said sulfuric acid at the other gas cleaning equipment consequently enables the operation there with lower acid concentration and hence a more efficient removal of fluorides there. Even- tually this results in savings at process water requirement.
  • fluoride concentration in the process gas is measured before entering the gas cooling tower and depending on the measured value additional steps can be taken to handle higher fluoride contents as described below.
  • the minimum but sub-stoichiometric amount must be dosed to meet the limit at the gas cooling tower outlet lower of e.g. 1 mg F /Nm 3 , which can be calculated out of the given operating data.
  • the majority of the fluoride will be absorbed at the gas cooling tower at low acid concentration and low temperature. A smaller fraction is absorbed upstream at the scrubber at higher acid concentration and higher temperature.
  • silicon dioxide S1O 2
  • sodium silicate Na 2 SiOs
  • potassium silicate K 2 S1O 3
  • waterglass-reaction with a stable product, e.g. sodi- urn silicate, which remains in solution.
  • the packing material of this tower is made of silica containing material, which reacts with the fluoride contained in the gas stream and forming soluble Fi 2 SiF 6 .
  • This packing has to be renewed or replenished periodically, subject to the fluoride content.
  • Those towers are quite large and massive and thus very costly. It has been observed that the surface of the ceramic packing material was covered with other substances (e.g. soot, lead, hydrocarbons), whereby the silica was thus not accessible anymore to the fluoride, resulting in very low or no effect of such installation.
  • the process gas is used for the production of FI 2 S0 4 whereby it is possible to produce a saleable product with minimum of impurities.
  • the invention Since the catalyst used for oxidation of SO 2 to SO 3 is sensible with regard to contained fluoride in the gas, the invention is not only necessary for a constant product quality but also extends operating life of downward process steps.
  • the process liquors contains between 1 and 33 wt.- %, preferably 2 and 30 wt.-%, FI 2 S0 4 . This affects the solubility of fluoride which increases the requirements to a flexible fluoride control.
  • a scrubber is foreseen between the quench and the packed bed tower for further cleaning.
  • the invention also covers a plant for the cleaning of a process gas containing SO2 with the features of claim 14.
  • a process with the feature of any of claims 1 to 13 can be operated in said plant.
  • Such a plant comprises at least one quench tower, at least one gas cooling tower and at least one electrostatic precipitator, preferably at least two electro- static precipitators in series.
  • condensate from the electrostatic precipitator(s) is withdrawn separately via at least one withdrawing conduit and guided via at least one conduit to a liquid effluent treatment plant.
  • the plant also contains a pump tank for adding a reaction agent and/or a packed bed tower whereby the packed bad contains silica.
  • the separate routing of the condensate/drain of the wet ESPs, containing the bulk of the sulfuric acid, directly to the liquid effluent dis- charge is key to this invention, - in conjunction with the fluoride tower operation as described above in case of high fluoride intake rates.
  • the gas cooling tower, scrubber and quench circulations are able to operate at minimized acid content and thus are enabled to better absorb fluorides.
  • the residual fluorides slipping into the fluoride removal tower are therefore mini- mized and the load on the fluoride tower reduced. Eventually, this also reduces the required amount of waterglass addition.
  • This system is based on the separate withdrawal of the wet ESP condensate plus the usage of a certain amount of waterglass. While the bulk of the fluorides are removed upstream of the first step ESP, particularly at the gas cooling tow- er, only the slippage of fluoride does enter the separate packed bed tower and thus the required reaction agent dosing is only a fraction of the equivalent amount that would be necessary to react with all of the fluoride entering the plant.
  • the fluoride content of the gas leaving the wet gas cleaning plant can be sustainably kept well below the standard of ⁇ 1 mg F/Nm 3 and hence the production of premium quality sulfuric acid can be ensured.
  • All process water required at the wet gas cleaning section is preferably or exclu- sively added to this fluoride tower, ensuring not only a very weak sulfuric acid concentration there, -usually well below 0.5 wt.-% H 2 S0 4 - but also removing the dissolved and stable precipitation product, e.g. Na2SiF 6 , countercurrent to the gas flow direction towards the quench tower and the liquid effluent treatment plant.
  • the risk of overdosing of flocculation agent and hence potential plugging of equipment is eliminated.
  • Fig. 1 shows a S0 2 cleaning according to the state of the art
  • Fig. 2 shows a S0 2 cleaning for relatively low fluoride concentrations according to the invention
  • Fig. 3 shows a S0 2 cleaning for medium fluoride concentrations accord- ing to the invention
  • Fig. 4 shows a S0 2 cleaning for relatively high fluoride concentrations according to the invention
  • Fig. 5 shows a S0 2 cleaning for very high fluoride concentrations accord- ing to the invention.
  • the standard wet gas cleaning process flow diagram of Fig.1 is characterized by a stepwise countercurrent stream of the aqueous phase (weak acid) to the direction of the gas stream.
  • Process gas is fed via conduit 11 into a quench tower 10. Therein, it is quenched with a quench stream fed in via conduit 14.
  • the quench stream is partly circulated via conduit 12, pump 13 and conduit 14. The other part of the quench stream is withdrawn via conduit 15.
  • the cooled process gas is transported via conduit 16 to a scrubber 20, where it is further cleaned with aqueous sulfuric acid fed in via conduit 23.
  • aqueous sulfuric acid fed in via conduit 23.
  • Parts of the scrubbing liquid is recirculated via conduit 21 , pump 22 and conduit 23 and parts are fed into conduit 24 for the quench tower.
  • the process gas is passed to a gas cooling tower 30 next.
  • Nec- essary fresh process water is added via a conduit 38 to the gas cooling tower 30.
  • Parts of the liquid in the sump of the gas cooling tower are circulated via conduit 31 , pump 32, conduit 33, heat exchanger 34 and conduit 35 while an- other part is withdrawn via conduit 36.
  • the concentration of impurities in the liquid is increasing stage by stage until discharged from the quench tower via conduit 15.
  • the cooled process gas is then send to a first electrostatic precipitator 40 and - if wanted - via conduit 41 forward to a second electrostatic precipitator 42.
  • the cleaned sulfur dioxide can be processed further for producing sulfuric acid.
  • Condensate of all electrostatic precipitators 40, 42 are withdrawn via conduits 44, 45 and 46 and passed into the sump of cool gas tower 30, scrubber 20, to the quench tower 10 from where it is discharged in the described way.
  • Sulfuric acid in the condensate at the wet electrostatic precipitators 40, 42 has highest concentration of typically 25 - 35% H 2 S0 4 , and will be fed upstream to the gas cooling tower circulation with typically only 1 - 10% H 2 S0 4 concentra- tion.
  • the invention is characterized by separately discharging the condensate from the wet Electrostatic precipitators from the wet gas cleaning section and hence a significant amount of sulfuric acid, as sketched in Fig.2.
  • Condensate of all electrostatic precipitators 40, 42 are withdrawn via conduits 44, 45 and 46 and passed separately to a collection tank 50. From there, it is pumped via pump 52 through conduits 51 and 53 to a liquid effluent treatment plant.
  • the flow sheet Fig.3 presents an additional dosing of a reaction agent. Said agent is hold available in pump tank 60 from where it is pumped via conduit 61 , dosing pump 62 and conduit 63 to the gas cooling tower 30 recirculation, like conduit 35 or into the sump of the gas cooling tower 30.
  • Fig. 4 shows the used of an additional packed bed tower 70.
  • process gas from the first electrostatic precipitator 40 is fed into this additional packed bed tower 70.
  • the packing material of this packed bed tower 70 is made of silica containing material, which reacts with the fluoride contained in the gas stream and forming soluble H 2 SiF 6 .
  • conduit 77 fresh water in injected into the packed bed tower 70. Parts of liquid is recirculated from the sump of the packed bed tower 70 via conduit 72, pump 73 and conduit 74 to the top of the packed bed tower 70 while another part is withdrawn via conduit 76 and passed to the gas cooling tower 30.
  • Another flow sheet in the sense of the invention is depicted in Fig.5.
  • an additional conduit 66 is foreseen. Via that conduit 66, it is possi- ble to feed additional reaction agent from pump tank 60 into the packed bed tower 70 to catch so peaks in the process gas' fluoride concentration.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Treating Waste Gases (AREA)
  • Gas Separation By Absorption (AREA)

Abstract

La présente invention décrit un procédé de nettoyage de SO2. En détail, un flux de gaz de traitement contenant au moins 1,0 % en poids-% de SO2 est rincé avant de passer dans une tour de filtration et est ensuite introduit dans au moins un précipitateur électrostatique. Le condensat provenant du ou des précipitateur électrostatique est retiré et dirigé séparément dans une installation de traitement d'eaux usées.
PCT/EP2018/050318 2018-01-08 2018-01-08 Procédé et installation d'épuration de gaz contenant du dioxyde de soufre WO2019134752A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/EP2018/050318 WO2019134752A1 (fr) 2018-01-08 2018-01-08 Procédé et installation d'épuration de gaz contenant du dioxyde de soufre
CN201890001472.0U CN213492919U (zh) 2018-01-08 2018-01-08 用于净化含有二氧化硫的气体的设备

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2018/050318 WO2019134752A1 (fr) 2018-01-08 2018-01-08 Procédé et installation d'épuration de gaz contenant du dioxyde de soufre

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WO2019134752A1 true WO2019134752A1 (fr) 2019-07-11

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021249628A1 (fr) * 2020-06-09 2021-12-16 Outotec (Finland) Oy Installation et procédé de production d'acide sulfurique à partir d'un dégagement gazeux à faible teneur en dioxyde de soufre

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1024065B (de) * 1955-09-23 1958-02-13 Metallgesellschaft Ag Verfahren zum Auswaschen von Fluorwasserstoff aus SO-haltigen Roestgasen
DE1085506B (de) * 1958-10-18 1960-07-21 Gerd Petersen Dr Ing Verfahren zum Auswaschen des Fluorgehaltes von Roestgasen
US4194889A (en) * 1977-03-11 1980-03-25 Metallgesellschaft Aktiengesellschaft Method of and apparatus for processing sulfur-containing exhaust gas
EP0101780A1 (fr) * 1982-08-07 1984-03-07 Hugo Petersen Ges. für verfahrenstechn. Anlagenbau mbH & Co KG Procédé pour la purification de gaz contenant SO2
DE3931270A1 (de) * 1988-10-03 1990-04-12 Biprokwas Verfahren zur reinigung von so(pfeil abwaerts)2(pfeil abwaerts) enthaltenden gasen aus einer anlage zur entschwefelung von verbrennungsgasen auf aktivem koks
EP0808660A1 (fr) * 1996-05-23 1997-11-26 Mitsubishi Heavy Industries, Ltd. Collecteur électrostatique de poussière

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1024065B (de) * 1955-09-23 1958-02-13 Metallgesellschaft Ag Verfahren zum Auswaschen von Fluorwasserstoff aus SO-haltigen Roestgasen
DE1085506B (de) * 1958-10-18 1960-07-21 Gerd Petersen Dr Ing Verfahren zum Auswaschen des Fluorgehaltes von Roestgasen
US4194889A (en) * 1977-03-11 1980-03-25 Metallgesellschaft Aktiengesellschaft Method of and apparatus for processing sulfur-containing exhaust gas
EP0101780A1 (fr) * 1982-08-07 1984-03-07 Hugo Petersen Ges. für verfahrenstechn. Anlagenbau mbH & Co KG Procédé pour la purification de gaz contenant SO2
DE3931270A1 (de) * 1988-10-03 1990-04-12 Biprokwas Verfahren zur reinigung von so(pfeil abwaerts)2(pfeil abwaerts) enthaltenden gasen aus einer anlage zur entschwefelung von verbrennungsgasen auf aktivem koks
EP0808660A1 (fr) * 1996-05-23 1997-11-26 Mitsubishi Heavy Industries, Ltd. Collecteur électrostatique de poussière

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021249628A1 (fr) * 2020-06-09 2021-12-16 Outotec (Finland) Oy Installation et procédé de production d'acide sulfurique à partir d'un dégagement gazeux à faible teneur en dioxyde de soufre

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Publication number Publication date
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