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WO2009092575A1 - Procédé de séparation de mercure - Google Patents

Procédé de séparation de mercure Download PDF

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Publication number
WO2009092575A1
WO2009092575A1 PCT/EP2009/000370 EP2009000370W WO2009092575A1 WO 2009092575 A1 WO2009092575 A1 WO 2009092575A1 EP 2009000370 W EP2009000370 W EP 2009000370W WO 2009092575 A1 WO2009092575 A1 WO 2009092575A1
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WO
WIPO (PCT)
Prior art keywords
sulfur
mercury
bromine
flue gas
mixture
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/EP2009/000370
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German (de)
English (en)
Inventor
Bernhard W. Vosteen
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VOSTEEN CONSULTING GmbH
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VOSTEEN CONSULTING GmbH
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Filing date
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Publication of WO2009092575A1 publication Critical patent/WO2009092575A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • B01D53/64—Heavy metals or compounds thereof, e.g. mercury
    • 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
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/30—Alkali metal compounds
    • B01D2251/304—Alkali metal compounds of sodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/40—Alkaline earth metal or magnesium compounds
    • B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/50—Inorganic acids
    • B01D2251/508—Sulfur dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/60—Inorganic bases or salts
    • B01D2251/608—Sulfates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/60—Heavy metals or heavy metal compounds
    • B01D2257/602—Mercury or mercury compounds
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2215/00—Preventing emissions
    • F23J2215/60—Heavy metals; Compounds thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2217/00—Intercepting solids
    • F23J2217/10—Intercepting solids by filters
    • F23J2217/102—Intercepting solids by filters electrostatic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2219/00—Treatment devices
    • F23J2219/40—Sorption with wet devices, e.g. scrubbers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/12—Heat utilisation in combustion or incineration of waste

Definitions

  • the invention relates to a method for the improved and cost-effective wet separation of mercury from combustion exhaust gases of high-temperature installations, in particular of power plants, waste incineration plants and other thermal treatment plants.
  • the exhaust gas streams of such high-temperature plants often contain mercury, which, once released into the environment, is also absorbed by humans via the food chain.
  • mercury concentrations in the exhaust gas of such high-temperature plants in particular of coal-fired power plants, are low, due to the large volume flows, the emitted mercury freight is considerable. Therefore, statutory emission limit values for the mercury concentrations or the mercury loads in the emitted clean gas, in particular after exhaust gas purification, have been established, the further reduction of which is desired.
  • the literature discloses a number of methods for reducing such mercury emissions.
  • Dry and wet deposition processes require as much mercury oxidation as possible, preferably in advance, that is already in the raw gas.
  • the aim is to convert the initially mercurous gaseous mercury present in the high-temperature range into its oxidized form, the so-called ionic mercury, which-in contrast to elemental mercury-can be largely washed out or adsorbed by adsorption.
  • a particularly advantageous method is described in DE 102 33 173 B4. It is characterized in that the flue gas is supplied in the high temperature zone bromine.
  • the bromine can be added in the form of bromine compounds or bromine-containing wastes as well as in elemental form.
  • the mercury preferably in the simultaneous presence of sulfur dioxide, very largely converted into the oxidized form.
  • sulfur often does not need to be added because it is introduced in sufficient quantities with the burnt materials, such as coal.
  • the method described above is distinguished from known methods for the separation of mercury from flue gases in that the desired complete oxidation of the mercury with low additions of bromine-containing compounds and thus comparatively low operating costs is achieved; Incidentally, the equipment required for the introduction of the oxidizing agent is low.
  • the oxidation of mercury using brominated additives is - in contrast to the oxidation with chlorine-containing additives - more effective and at the same time largely insensitive to sulfur dioxide, as is usually present in power plant flue gases or flue gases from waste incineration plants. In contrast to liberated chlorine, the liberated bromine is not consumed by SO 2 in the high temperature range.
  • the bromine-based method is suitable for the mercury removal from flue gases of various high-temperature processes.
  • US Pat. No. 7,037,474 B2 describes a process in which the mercury is first oxidized by means of chlorine-containing additives and then in scrubber water by means of this added hydrogen sulphide H 2 S or by addition of other substances such as, for example, sulphidic wastewaters, paper-making wastewater, thioacetamide or alkali sulfides in the form of HgS is precipitated.
  • SA et. ai . " Usingwet FGD Systems to Absorb Mercury", POWER October 2004, pp. 44-49. It should be remembered that the technical handling of hydrogen sulfide or, for example, sodium hydrogen sulfide is not without problems.
  • Likata, A. describes in the "Coal-Fired Power Plant Mercury Control by Injecting Sodium Tetra- sulphide" in the ICAC Forum 03 a method for mercury sulfidation already in the flue gas, characterized in that sodium tetrasulfide Na 2 S 4 at temperatures around 170 0 C in the flue gas is injected.
  • the sodium tetrasulfide decomposes rapidly in the hot flue gas and releases highly active sulfur, which still leads to HgS as fine dust in the flue gas or, for example, in a downstream fabric filter.
  • TMT trimercapto-s-triazine sodium salt
  • All of the aforementioned methods have in common that their effect depends on the specific flue gas quality of the high-temperature process, that is to say of its kind - for example high-temperature combustion, such as in a coal-fired melt chamber boiler, or low-temperature combustion, such as stationary or circulating fluidized bed combustion - and of the fuel and the associated combustion parameters.
  • the effect also depends on the type of flue gas scrubbing, such as a one- or multi-stage scrubber system, and the associated scrubber parameters - such as pH, fresh water drainage, scrubber forced aeration, gypsum formation in limestone-based desulfurization, low-solids desulfurization using NaOH.
  • the type of flue gas scrubbing such as a one- or multi-stage scrubber system
  • the associated scrubber parameters such as pH, fresh water drainage, scrubber forced aeration, gypsum formation in limestone-based desulfurization, low-solids desulfurization using NaOH.
  • a precipitation with TMT can not be carried out in the extremely acidic washing waters in the first scrubber stage behind waste incineration plants, but in the following weakly acidic, neutral or alkaline second scrubber stage.
  • the specific consumption and the price of the precipitants is important.
  • ecotoxicological properties of the precipitants are also of interest.
  • the aquatic toxicity, degradability and mutagenicity of the precipitants are also of interest with regard to the further whereabouts of the treated wastewater, for example heavy metal post-precipitation.
  • aquatic toxicity some organic sulfur compounds, such as, for example, sodium trithiocarbonate or dimethyldithiocarbamate, exhibit, inter alia, considerable fish toxicity.
  • gypsum or calcium sulphate dihydrate is produced, which - with sufficient purity - is used in the gypsum industry is used.
  • the calcium sulfate dihydrate is thermally calcined, whether in stucco or stucco rotary kilns.
  • the fired gypsum is used for the production of building materials for interior work.
  • no mercury should be released.
  • the gypsum products produced are also unlikely to contain mercury. Therefore mercury precipitation should avoid contamination of the gypsum with mercury compounds of any kind.
  • the object is to provide a universally applicable, improved method for the wet separation of mercury from the flue gases of high-temperature systems.
  • the method should be usable and inexpensive both in coal combustion in power plants and in waste incineration. It should bring about a substantial reduction of the air and water side mercury emission.
  • a by-product such as gypsum should be loaded only to a small extent with mercury compounds. In particular, a residual load of mercury in gypsum in thermally stable form to occur.
  • a sulfur-containing compound - such as sulfur dioxide SO 2
  • the flue gas is subjected to a particular multi-stage purification, comprising at least one particular multi-stage wet scrubbing, wherein a washing liquid of the wet scrubbing in at least one of the washing stages, in particular the wet scrubbing at least one substance is supplied, comprising at least one alkali or Erdalkalipolysulfid or a mixture of several Alkali and / or Erdalkalipolysulfide is supplied.
  • at least one polysulfide is added in the form of an aqueous solution for precipitating the dissolved mercury.
  • Claimed is also a method for the separation of mercury from flue gases of Hochternperaturaniagen, especially of power plants and waste incineration plants, in which the possibly multi-stage firing and / or the flue gas in one of the firing system downstream component bromine and / or a bromine-containing compound and / or a mixture various brominated compounds is supplied, wherein the temperature during contact of the bromine-containing compound with the flue gas is at least 500 0 C, the combustion in the presence of a sulfur-containing compound (SO 2 ), with the addition of sulfur and / or a sulfur-containing compound and / or a mixture followed by the flue gas is subjected to a possibly multi-stage wet scrubbing, the washing liquid in at least one of the washing stages an alkali or Erdalkalipolysulfid or a mixture of several alkali and / or Erdalkalipolysulfide is supplied, geg if appropriate also with other substances, especially in admixture with one and / or more alkal
  • the washed gypsum is largely free of mercury and - as a residual mercury is present - this is bound as a thermally stable HgS in gypsum. Furthermore, surprisingly, the amount of bromine to be added decreases, so that the corresponding costs for bromine-containing compounds are reduced.
  • High-temperature systems are, for example, power plants, in particular coal-fired power plants, or waste incineration plants. Also, the method is applicable to other high temperature systems.
  • the furnace is in one stage. Another embodiment provides for a two-stage firing. It is also provided in further embodiments that the furnace has more than two stages.
  • the bromine and / or a bromine-containing compound and / or a mixture of various bromine-containing compounds is supplied in one embodiment of the furnace.
  • bromine and / or a bromine-containing compound and / or a mixture of various bromine-containing compounds is fed to a plant part downstream of the furnace.
  • bromine and / or a bromine-containing compound and / or a mixture of various bromine-containing compounds is fed to the furnace and to a downstream part of the furnace.
  • sodium bromide (NaBr) in particular in an aqueous solution, fed.
  • WEI terhin embodiments are provided in which CaBr 2 . KBr and / or NH 4 Br is added.
  • bromine compounds are used which release under the conditions of the hot flue gas HBr / Br 2 , for example with support by sulfation of the compounds by means of SO 2 in the flue gas.
  • organic bromine compounds such as occur for example in flame retardants can be used.
  • waste from electronic equipment such as television casings and other electronic waste, preferably up to 5% by weight, based on the total amount of waste, of bromine.
  • the combustion takes place in one embodiment in the presence of a sulfur-containing compound.
  • a sulfur-containing compound For example, sulfur dioxide (SO 2 ) is provided in one embodiment.
  • sulfur is supplied to the combustion chamber, from which SO 2 is produced by the combustion.
  • SO 2 sulfur is supplied to the combustion chamber, from which SO 2 is produced by the combustion.
  • a sulfur-containing compound can be present in sulphurous coals.
  • the combustion takes place with the addition of sulfur and / or a sulfur-containing compound and / or a mixture of various sulfur-containing compounds.
  • sulfur dioxide can be supplied to the combustion material and / or introduced into the combustion chamber.
  • the combustion takes place in the presence of a sulfur-containing compound which is preferably already present in the kiln and also with the addition of sulfur and / or a sulfur-containing compound and / or a mixture of various sulfur-containing compounds.
  • a bromine-containing compound results in a gas phase reaction between mercury and bromine in the presence of sulfur dioxide. Since in conventional combustion and other high-temperature processes usually sulfur dioxide, such as coal or waste, arises, is for an embodiment of the method usually a sufficient supply of sulfur-containing compound available. There is sufficient supply if, with the addition of a bromine-containing compound to the furnace, the content of sulfur dioxide in the flue gas before the flue gas cleaning is significantly greater than zero. If, for example, no or insufficient sulfur dioxide is formed in a combustion process, a sulfur-containing compound can be supplied to the process. This can take place in the form of free or bound sulfur, for example sulfur granules, waste sulfuric acid or other sulfur-rich wastes.
  • a sulfur-containing compound can also be added, for example to reduce too high a content of free halogens in the flue gas, if, for example, more bromine-containing Compound has been added, as for the oxidation of the present mercury is necessary.
  • the metered addition of a sulfur-containing compound can be carried out, for example, according to the process described in patent application DE 101 31 464 A1 for low-corrosion and low-emission co-combustion of highly halogenated waste in waste incineration plants.
  • the disclosure of DE 101 31 464 A1 is hereby made the subject of the present invention in its entirety. According to this method, sulfur or a corresponding sulfur carrier is metered controlled into the primary and / or secondary combustion chamber.
  • the regulation of the amount of sulfur is essentially proportional to the current recorded total halogen load in the boiler flue gas with the waste.
  • the added sulfur burns in the furnace to sulfur dioxide, which leads internally to an extensive suppression of interim formed free halogens in the boiler flue gas and subsequently to the stable halogen incorporation in the alkaline laundry.
  • the addition of sulfur is controlled in such a way that the target sulfur dioxide content in the flue gas at the boiler inlet or the target sulfur dioxide residual content at the boiler end, ie in the boiler raw gas before, for example, a wet flue gas cleaning, are maintained in steady-state operation via a simple primary control circuit.
  • the purification of the flue gas takes place in a preferred embodiment in one stage.
  • at least two stages of the flue gas cleaning are provided.
  • the cleaning comprises at least one flue gas scrubbing.
  • the flue gas scrubbing is at least two stages.
  • a bromine-based oxidation of mercury in particular with the addition of aqueous solutions of alkali or Erdalka- lipolysulfiden directly to the limestone-based REA scrubber, preferably after coal boilers, or directly to the scrubber stages of a multi-stage scrubbing system, especially after a waste incineration or other high-temperature processes , combined.
  • the polysulfide is a mixture of sodium polysulfides.
  • other sulfides and / or sulfur-containing anions are added to the polysulfide mixture.
  • the mixture comprises at least thiosulphate.
  • the polysulfide is a mixture of calcium is polysulfides.
  • a further embodiment provides that the polysulfides are supplied to the washing liquid in the form of an aqueous solution or as a slurry.
  • the polysulfides are fed in a homogeneous aqueous solution or, if the solubility limits are exceeded, as a slurry of suspending solids in the aqueous phase.
  • the polysulfide contains anions having 3 and 4 sulfur atoms as essential constituents. It is also provided according to a variant that the washing liquid or the polysulfide solution used alkali or Erdalkalibromid is added.
  • the mass ratio of polysulfide - calculated as precipitation-active sulfur - to mercury Hg ges is according to one embodiment between 0.5 and 40.
  • the mass ratio Br ges to Hg ges is in one embodiment at least 10 mg Br ges / mg Hg ges , and is preferably in one range of about 25 mg Br tot / mg Hg tot to particular about 1000 mg Br tot / mg Hg tot, further preferably in a range up to about 500 mg Br tot / mg Hg tot, still more preferably in a range up to about 300 mg of Br ges / mg Hg ges .
  • Precipitating sulfur is the proportion of sulfur available as sulfide ion (S 2 ' ) for sulfidic heavy metal precipitation.
  • the amount of S a ⁇ t is determined analytically by precipitation with suitable heavy metal ions in, for example, Cd 2+ and analytical determination of the sulfidically precipitated heavy metal.
  • Hg ges as Hg-freight or Hg mass flow in the flue gas is preferably calculated from the analytically determined Hg content of the combusted material such as waste, sewage sludge or coal multiplied by its flow rate.
  • the corresponding Hg ges concentration in the flue gas results by the said Hg mass flow is divided by the volume flow of the combustion gas under standard conditions.
  • the combustion gas volume flow can be calculated on the basis of an elemental analysis and with reference to the oxygen content in the flue gas.
  • the specific amount of combustion gas amounts to about 10 Nm 3 tr./kg anhydrous coal when German hard coal is burned below 3% by volume ReSt-O 2 .
  • the unit Nm 3 stands for standard cubic meter.
  • waste such as sewage sludge this can be, for example, 6 to 8 Nm 3 tr./kg sewage sludge dry matter, depending on the oxygen content of, for example 6% by volume in fluidized bed combustion up to 11% by volume, for example in rotary kiln firing.
  • polysulfides added to REA scrubbers of coal-fired power plants in particular with alkali and / or alkaline earth bromides, are added.
  • the optionally mixed with alkali and / or Erdalkalibromiden polysulfides are added to the scrubber stages of waste incineration plants.
  • a variant provides that the dosage of polysulfides and / or of bromine or bromine compounds as oxidizing agent is readjusted automatically according to, for example, the continuously measured content of mercury in the clean gas. Also, the content of mercury can be determined discontinuously or in random samples.
  • the polysulfides used according to the invention can be prepared in a known manner by reacting the corresponding alkali metal or alkaline earth metal hydroxides with elemental sulfur, and are preferably mixtures of various sulfur-containing salts comprising as main constituent polysulfide compounds (polysulfide mixture), preferably with S 3 2 " -, S 4 second "- and S 5 2" anions They preferably comprise in addition to small amounts of sulfide, hydrogen sulfide and other sulfur-containing anions larger amounts of thiosulfate and as essential components polysulfides, with tri-, tetra- and polysulfide (S 3 2 '-., S 4 2 - and S 5 2 ' anions) as main components, and are preferably stable in a neutral and alkaline solution.
  • the polyhydric sulphides underlying the polysulphides - so-called sulphanes - are liberated, which slowly increase to S x .
  • Hung example decompose to H 2 S.
  • a Polysulfidmi- research includes these more poly sulfides Na 2 S x with an average of x> 5, that is, more S atoms than in the tetrasulfide Na 2 S 4 present, wherein preferably for x a distribution of 2 to 7 is provided.
  • at x 3, 4, 5 is the maximum.
  • the filling-active sulfur content of the polysulfide material or mixture used is preferably at least 18% by weight, more preferably at least 22% by weight, based on the total amount of the material or of the mixture.
  • polysulfide mixture may include sodium thiosulphate (Na 2 S 2 O 3 ), sodium hydroxide, potassium bromide and / or another alkali or alkaline earth bromide including ammonium bromide.
  • sodium thiosulphate Na 2 S 2 O 3
  • sodium hydroxide sodium hydroxide
  • potassium bromide potassium bromide
  • the polysulfide mixture has polysulfide anions which are twice negative in the alkaline and dissociate to 2Na + and " S- (Sy) -S " ions.
  • Y can be 0.1, 2, 3, 4 or greater than 4.
  • FIG. 1 is a sketch of a coal-fired industrial power plant
  • Fig. 2 is a sketch of a Drehrohrfeuerung
  • FIG. 3 shows a diagram for the increase of the mercury load of a REA gypsum with the Hg load in the raw gas
  • FIG. 6 shows a diagram of an optimization of a sewage sludge incinerator
  • Fig. 8 shows the analysis of Fig. 7 with changed abscissa.
  • FIG. 1 shows by way of example the sketch of a coal-fired industrial power plant 1 with two parallel melt chamber boilers 2.1, 2.2 with air preheaters 3.1, 3.2, electrostatic precipitators 4.1, 4.2, and subsequently with a common, limestone-based wet REA 5 and two downstream tail end SCR DeNOx denitrification plants 6.1. 6.2.
  • Coal 7 is enriched with CaBr 2 8. This is the melting boilers 2 supplied.
  • the electrostatic precipitator 4 dust is filtered out of the exhaust gas and over a dust return 9 the melting boilers 2 fed again.
  • the dust-free gas is fed to a wet REA 5.
  • There polysulfide 11 is supplied.
  • a REA gypsum 13 is deposited via a centrifuge 14.
  • a hydrocyclone treatment 12 separates wastewater 15 from RAA sludge 16.
  • the RAA sludge 16 is preferably pressed or dewatered in a filter press 17.
  • RAA sludge stands for REA wastewater treatment sludge or fine sludge in REA wastewater, which flows with it to the REA wastewater treatment plant.
  • the gas is then de-nitrogenized in the deNOx denitrification plants 6.
  • the DeNOx denitrification plant 6 has at least one gas preheater 18, a natural gas burner 19 and an ammonia dosing 20. Thereafter, the clean gas 21 leaves the chimney 22.
  • FIG. 2 shows, as a further example according to the invention, a rotary kiln firing for solid, pasty and liquid hazardous wastes with waste heat boiler 23 and subsequently with a two-staged multistage wet scrubber 24, condensation electrostatic precipitator 25 and with a common tail-end SCR DeNOx denitrification plant 6.
  • FIG. 2 shows that container waste 26, liquid waste 27 and bunker waste 28 are first incinerated in a rotary kiln burner 29 in a post-combustion chamber burner 30 and subsequently in the waste heat boiler 23. Before incineration, the refuse 26, 27, 28 is enriched with NaBr 31.
  • the acidic scrubber 32 is added polysulfide 33 in one embodiment.
  • the alkaline scrubber 34 polysulfide 33 is added.
  • the addition of the polysulfide 33 according to the invention can be carried out both to the alkaline scrubber 34 and to the acid scrubber 32 or both.
  • the SRW 35 water 36 is supplied.
  • the acid waste water 37 and the alkaline waste water 38 are discharged.
  • Fine dust 39 is removed from the gas via the condensation filter 25.
  • flue gases 40 are supplied and this then entstickt in DeNOx denitrification 6.
  • the clean gas 21 then leaves the chimney 22.
  • upstream SCR DeNOy denitrification 6 before Na ⁇ scrubber 24 is required for more than 90% mercury separation mass ratio Br to Hg up to 500 mg Br ges / mg Hg ges
  • upstream SCR DeNO X- denitrification only about 50 to 200 mg Br ges / mg Hg ges (are required, which shows the considerable advantage of the method according to the invention.
  • alkali or Erdalkalibromid as oxidizing additive and sodium polysulfide as precipitant. Both substances are preferably used as aqueous solutions.
  • the bromine component is either added to the combustion material, for example in Fig. 1 as coal or in Fig. 2 as solid waste or injected into the high-temperature zone of combustion, be it in a main furnace or in a secondary combustion chamber.
  • the polysulphide is added to the scrubber water circuit (s). 1 shows, for example, that in the case of a wet REA 5 behind the power plant 1, the Polysullfid addition can be done, for example, in one of the Umpumpnikin the REA suspension.
  • the polysulfide addition may be to both the alkaline scrubber section 32 and the acid scrubber section 34.
  • the distribution of the polyol sulfide on the scrubber areas 32, 34 influences the overall mercury removal.
  • a MA- Optimization of the mercury removal is achieved, for example, by feeding the by far largest part of the polysulfide to the first, strongly acidic scrubber stage.
  • the required, matched amounts of reagents are adjusted according to the level of mercury concentration in the flue gas in certain proportions and readjusted.
  • the coordinated quantity readjustment can be carried out automatically.
  • polysulfide described with its content of precipitation-active sulfur S 2 '
  • S 2 ' / Hg mass flow ratios in the range 0.5 to 50 are required.
  • Is carried out according to the invention in addition to the Brcmid addition also sine polysulfide addition, it is possible to reduce it eds -Massenstromread by increasing the S 2 VHg- mass flow ratio significantly, and vice versa the necessary Br tot /.
  • a surprising result of the application of the method according to the invention to limestone-based wet REAs 5 of coal-fired power plants 1 is that almost all of the precipitated mercury is found in the fine sludge 16 and only insignificant amounts remain in the gypsum 13.
  • HgSO 4 , HgO and HgS are not appreciably mobilized at about 180 ° C.
  • HgCl 2 , HgBr 2 and Hg (NO 3 ) 2 * H 2 O have considerable mobilization potential.
  • Hg 2 Cl 2 occupies an intermediate position.
  • TMT15 is a trimercapto-s-triazine sodium salt in a 15% by weight solution from Evionik-Degussa, in the deposition of mercury.
  • TMT15 is the trade name of a trimercapto-s-triazine sodium salt in a 15% by weight solution of the manufacturer Evionik-Degussa, available from Evonik Industries AG, Rellinghauser Strasse 1-11, 45128 Essen, Germany.
  • wet REA 5 (pH 5.3), as shown in Fig. 3, was added a dilute TMT15 solution on two days.
  • the experiments were carried out with Hg / Cl-doped Ie and raised Hg deposition in the REA performed at NulNast.
  • the tandem curve L shows the injection into the gypsum with increasing mercury load by Hg spiking of the raw gas to 660 ⁇ g / Nm 3 tr.
  • the tendency curve L begins does not intersect the zero on the axis of abscissa, since, for example, via limestone to a Hg foreign entry M comes.
  • the values labeled K indicate the mg mg / kg gypsum TS ratio after a TMT15 addition to the REA scrubber.
  • Fig. 4 shows a multi-stage flue gas scrubber 69.
  • WBF stationary fluidized bed burners
  • EGR electrostatic precipitator
  • FIG. 4 shows the raw gas A in the first scrubber 32 with supplied safety water F via an atomizer 70.
  • the scrubbers are in particular GRANILAB scrubbers G1, G2. These preferably consist in each case of an electro-filtering Venturi tube 77, a dynamic filter and a downstream droplet separator 79.
  • the first scrubber stage I there is a pH of 0.5 to 1 (acidic).
  • the first scrubber stage I has a scrubber sump volume of 2m 3 .
  • the first scrubber stage I has a throughput of 0.1 m 3 / h. The flow rate indicates the slurry or wastewater stream from the scrubber.
  • the venturi tube 77 of the filtering module M has an electrode arranged at the longitudinal axis, preferably connected to a high-voltage generator, and an atomizer 78 at the outlet. Venturi tube 77 accelerates the saturated flue gases. The resulting adiabatic stress relaxation causes a condensation of water vapor on the fine dust particles, which act as condensation nuclei here.
  • the particles which have been enlarged by the enveloping condensation film and become electrically conductive become negatively charged on the way along the said electrode. Furthermore, the water droplets sprayed out by the atomizer 78 are positively charged by the polarizing effect of the electrode tip.
  • the gas with the negatively charged particles flows through a catch screen, not shown in more detail, which consists of positively charged droplets sprayed in countercurrent at high speed.
  • the negatively charged particles are separated as far as possible by electrostatic attraction on the positively charged parachute.
  • the washing liquid for the parachute is collected and reused.
  • evaporation losses are compensated by the supply of fresh water B in the circulation.
  • a slurry can preferably be carried out in the GRANI-LAB scrubbers G1, G2.
  • the downstream radial drop separator CYCLO-LAB 79 ensures the safe separation of entrained water droplets by a centrifugal effect.
  • a blower 80 conveys the clean gas C into the chimney 22.
  • the scrubber slurry H is fed to a reaction tank 71. Furthermore, a flocculant 73 and a special precipitant 74 are introduced into the reaction tank 71, milk of lime 72. In a settling tank 75, clear water D is separated from the sludge. The sludge passes through a filter press 76 and is pressed into filter cake E.
  • This plant has been operated with respect to Hg deposition so far by the LAB method, namely with the addition of the particularly expensive oxidant NaCIO 2 at the entrance of the flue gas in the first, strong acid scrubber stage 1 in the scrubber 32 and with the addition of TMT15 to the second, only weak alkaline scrubber stage 2 in the scrubber 34.
  • the mercury measurement at the chimney 22 is carried out with a TÜV-approved MERCEM-Kontimess réelle the company Sick-Maihack. The mercury separation achieved in this way Apart from occasionally disturbing fluctuations in the Hg concentration at the chimney 22, it was good, but expensive.
  • the wet sludge pre-dried to 43% dry matter (DM) had a mercury content of about 1 to 1.5 mg / kg DM. This results in boiler raw gas preferably at about 15,000 Nm 3 tr./h to a mercury concentration of about 150 ug / Nm ⁇ r.
  • the mercury concentration at the chimney 22 should be below the permissible half-hourly average of 30 ⁇ g / Nm 3 tr (at 1 1% by volume O 2 ), preferably significantly lower at 10 to 15 ⁇ g / Nm 3 tr.
  • FIG. 5 shows an exemplary measurement result on the system WSB2 according to FIG. 4 after conversion to the method according to the invention and with optimized bromine addition and polysulfide addition with a view to the lowest possible concentration of mercury in the stack.
  • 10 ⁇ g Hg / Nm 3 tr. 11 vol% O 2
  • the narrow peak peak 81 at 10:40 was based on a short-term disruption in the power supply company in the field of Hg tot -Kontimess réelles.
  • Fig. 6 describes the way of a leading optimization.
  • the parameters were varied on the sewage sludge incinerator according to FIG. 4 in order to find out the correlations between bromide addition and polysulphide addition which are suspected in accordance with the invention.
  • the diagram shows a first measurement curve 82 for Hg ges at the chimney, a second measurement curve 83 for S2- / Hg to the scrubbers 1 and 2 in total, a third measurement curve 84 for S 2 " / Hg ges only to the scrubber 2 and a fourth measurement curve 85 for a Br / Hg mass ratio.
  • Hg ges referred to in the mass ratios as a reference the mass flow of mercury in the raw gas of about 2.25 g / h. This value results from the above-mentioned Hg ges concentration in the raw gas - 150 ug / Nm 3 tr. Or more - and under about 80% partial load driven average flue gas volume flow of preferably 15,000 Nm 3 tr./h.
  • a polysulfide mixture according to the invention such as PRAVO is to be understood as meaning a mixture which preferably comprises sodium hydroxide having a proportion by weight of from about 1% to about 5%. Furthermore, it is provided in one embodiment that the mixture has sodium polysulfide with a weight fraction of about 10% to about 20%. It is also provided according to a development that the mixture comprises sulfur, preferably active sulfur, with a weight fraction of about 10% to about 30%. The proportions by weight are in each case based on the total amount of the mixture. Furthermore, according to one embodiment, the mixture may comprise water. Preferably, the mixture has a pH of about 12.8 to about 13.6 (PANche- mie Dr. Gabor Fülöp e.K. in Kerpen, Germany).
  • Fig. 7 e now shows a first analysis of the variation of PRAVO, that the mass ratio S 2 7HG ges on the one hand, and of sodium bromide, that of the mass ratio Br tot / Hgg s other hand.
  • the arrow O shows a variation of S 2 VHg at approximately constant Br / Hg. Abscissa is in the mass ratio S 2 7Hg ges .
  • the arrow P shows a variation of Br / Hg at approximately constant S 2 7HG sat. It can be seen, for example, that an Hg separation efficiency of> 90% can be achieved in different ways, with a low Br ges / Hg g e S by increasing S 2 7Hg ges or vice versa.
  • Fig. 8 further shows measurement data 86 in which NaBr was added to the slurry, and measurement data 87 in which NaBr was injected via three lances.
  • bromine fulfills two tasks: a) the mercury oxidation in the boiler flue gas and b) the mercury complexing in an acid scrubber stage 1, for example as shown in FIG. 4, to which not only bromide contributes, but also optionally the bromide from sewage sludge incineration chloride.

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Abstract

L'invention propose un procédé de séparation du mercure de gaz de fumée d'installations à haute température, en particulier de centrales électriques et d'installations d'incinération d'ordures, dans lequel du brome et/ou un composant contenant du brome et/ou un mélange de différents composants contenant du brome sont apportés, en particulier en plusieurs étapes, à la combustion et/ou au gaz de fumée dans une partie de l'installation disposée en aval de la combustion, la température lors du contact entre le composé contenant du brome et les gaz de fumée étant d'au moins 500°C, la combustion ayant lieu en présence d'un composé contenant du soufre, par exemple du dioxyde de soufre SO2, éventuellement avec addition de soufre et/ou d'un composé contenant du soufre et/ou d'un mélange de différents composés contenant du soufre. Ensuite, les gaz de fumée subissent une épuration, en particulier en plusieurs étapes, qui comprend au moins un lavage, en particulier en plusieurs étapes, en ajoutant au liquide de lavage dans au moins l'une des étapes de lavage une substance qui comprend au moins un polysulfure de métal alcalin ou alcalino-terreux ou un mélange de plusieurs polysulfures de métaux alcalins et/ou alcalino-terreux. En particulier, au moins un polysulfure en forme de solution aqueuse destiné à précipiter le mercure dissous est ajouté.
PCT/EP2009/000370 2008-01-23 2009-01-22 Procédé de séparation de mercure Ceased WO2009092575A1 (fr)

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Cited By (3)

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WO2010009803A1 (fr) * 2008-07-19 2010-01-28 Currenta Gmbh & Co. Ohg Procédé de dépôt de mercure respectivement de ses composés, à partir de flux d'air vicié
US8632742B2 (en) 2007-12-07 2014-01-21 Nalco Company Methods of controlling mercury emission
CN104524952A (zh) * 2015-01-13 2015-04-22 崔涛 一种烟气处理设备

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JP6095923B2 (ja) * 2012-09-14 2017-03-15 三菱日立パワーシステムズ株式会社 排ガス中の水銀処理システム
AU2016200890A1 (en) * 2015-02-13 2016-09-01 The Babcock & Wilcox Company Method and apparatus for removing mercury from a flue gas stream
FR3072887B1 (fr) * 2017-10-26 2022-05-13 Lab Sa Procede de demercurisation d'effluents gazeux

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EP1386655A1 (fr) * 2002-07-22 2004-02-04 Bayer Aktiengesellschaft Procédé pour l'élimination de mercure de gaz de combustion
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JPS6253726A (ja) * 1985-08-30 1987-03-09 Nippon Kokan Kk <Nkk> ゴミ焼却排ガスの水銀除去方法
US4834953A (en) * 1987-09-30 1989-05-30 Mobil Oil Corporation Process for removing residual mercury from treated natural gas
US5419884A (en) * 1993-02-19 1995-05-30 Mobil Oil Corporation Regenerative mercury removal process
EP0709128A2 (fr) * 1994-10-25 1996-05-01 L. &amp; C. Steinmüller GmbH Procédé pour éliminer le mercure d'un gaz contenant du mercure
DE19850054A1 (de) * 1998-10-30 2000-05-04 Karlsruhe Forschzent Verfahren zum Abscheiden von Quecksilber aus Rauchgas
EP1386655A1 (fr) * 2002-07-22 2004-02-04 Bayer Aktiengesellschaft Procédé pour l'élimination de mercure de gaz de combustion
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US8632742B2 (en) 2007-12-07 2014-01-21 Nalco Company Methods of controlling mercury emission
WO2010009803A1 (fr) * 2008-07-19 2010-01-28 Currenta Gmbh & Co. Ohg Procédé de dépôt de mercure respectivement de ses composés, à partir de flux d'air vicié
CN104524952A (zh) * 2015-01-13 2015-04-22 崔涛 一种烟气处理设备

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