CA2261037A1 - Additive to be sprayed into the combustion chambers of heating plants and process for preventing high temperature corrosion - Google Patents
Additive to be sprayed into the combustion chambers of heating plants and process for preventing high temperature corrosion Download PDFInfo
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- CA2261037A1 CA2261037A1 CA002261037A CA2261037A CA2261037A1 CA 2261037 A1 CA2261037 A1 CA 2261037A1 CA 002261037 A CA002261037 A CA 002261037A CA 2261037 A CA2261037 A CA 2261037A CA 2261037 A1 CA2261037 A1 CA 2261037A1
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- Prior art keywords
- nozzled
- activated bentonite
- high temperature
- glass
- additive
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- 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
- B01D53/38—Removing components of undefined structure
-
- 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
- B01D53/70—Organic 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
- B01D53/34—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
-
- 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
- B01D53/79—Injecting reactants
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L10/00—Use of additives to fuels or fires for particular purposes
- C10L10/02—Use of additives to fuels or fires for particular purposes for reducing smoke development
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L10/00—Use of additives to fuels or fires for particular purposes
- C10L10/04—Use of additives to fuels or fires for particular purposes for minimising corrosion or incrustation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/44—Details; Accessories
- F23G5/48—Preventing corrosion
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/602—Oxides
-
- 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
- B01D2257/206—Organic halogen compounds
-
- 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
- F23J2215/30—Halogen; Compounds thereof
- F23J2215/301—Dioxins; Furans
-
- 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
- F23J2219/00—Treatment devices
- F23J2219/60—Sorption with dry devices, e.g. beds
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Treating Waste Gases (AREA)
- Processing Of Solid Wastes (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Gasification And Melting Of Waste (AREA)
- Incineration Of Waste (AREA)
- Coating By Spraying Or Casting (AREA)
- Fertilizers (AREA)
Abstract
An additive is sprayed into the combustion chambers of heating and waste incineration plants to prevent high temperature corrosion and to reduce the fly ash proportion in the exhaust gas. Also disclosed is a process for preventing high temperature corrosion and for reducing the fly ash proportion in the exhaust gas from heating and waste incineration plants. The disclosed additive consists of acid activated bentonite and/or oxide melts, in particular glass powder or glass dust with a melting point below 1000 ~C, and is sprayed into the gas chamber in areas in which the gas temperature exceeds 700 ~C.
Description
' ? ~ ?~
Method for Preventinq Hiqh Tem~erature Corrosion The invention relates to a method for preventing high temperature chlorine corrosion in combustion chambers of firing means and waste incineration plants and reducing the flue dust portion contained in the combustion offgases.
Known methods for preventing corrosion were aimed at reducing corrosion in incineration plants and, in particular, on the heat exchanger surfaces of boilers by effecting reactions in the gas phase in order to deactivate corrosive substances. To this end, magnesium oxide is usually nozzled in, thereby enabling primarily high temperature sulfate corrosion to be substantially reduced at temperatures of above 480~C. This is obtained in that, at an excess of MgO contained in the deposits forming, for instance, on the superheater tubes, MgSO4 instead of alkali pyrosulfates is formed with the SO2 of the smoke gas. At temperatures of above 480~C alkali pyrosulfates will, in fact, dissolve the layer of scale, thus leading to catastrophic corrosion damages.
MgO is ineffective against corrosive damages caused by chlorine forming during the sulfation of chlorides.
That type of corrosion has been increasingly encountered in the firing space regions of refuse incineration plants during the past years, since the composition of refuse has changed on account of refuse separation, on the one hand and a higher smoke gas temperature must be observed as in accordance with legal provisions, on the other hand (800~C for at least 2 seconds within the combustion chamber).
From WO 95/11287 it has already become known to nozzle cerium compounds such as iron cerium, cerium oxides and/or cerium oxide hydrates in powder form. According to that previous proposal, it was possible to nozzle in such cerium compounds together with magnesium oxide, primarily aiming at substantially reducing the cleaning expenditures involved in the removal of deposits from the internal sides of plant parts and thereby enabling longer campaign times than in known processes. In particular, it was intended to preserve the action of, and no longer deteriorate, passivating layers already formed on the upper surfaces of plant parts for the protection of the same. Those cerium compounds such as iron cerium, cerium oxide or cerium oxide hydrate were to safeguard reducing zones in the vicinity of the walls in order to thereby reduce corrosion. The effect of cerium compounds in the manner of oxidation catalysts induces afterburning in reducing regions of the smoke gas, thereby reliably preventing the reduction of an oxide layer of scale or rust already formed for passivation. The cerium compounds also were to become active against chloride ion corrosion in order to thereby ensure oxidation to basically less dangerous chlorine gas in molecular form.
The use of additives of this type, however, involves relatively high costs and has proved to be insufficiently effective, in particular in connection with high temperature chlorine corrosion, in which chlorine gases dissociate again.
Attempts to admix to the charging material to be burnt filtering aids and, in particular, inorganic filtering aids based on active silicic acid containing silanol groups likewise have proved to be relatively expensive, since additives will show effects only in percentage ranges due to their being inhomogenously distributed in refuse.
For recycling into the circuit of a melting chamber firing means pollutant-loaded residues such as, for instance, filter ashes, adsorbents or the like while adding used glass and/or limestone chips, DE-A-4 021 362 has already proposed to introduce the absorber into the circuit of a melting chamber firing means with complete ash recycling. The absorber may be fed into the the smoke gas path and/or into the ash recirculation and/or into the slag discharge and/or along with coal, wherein broken used glass and/or limestone chips may be dosed in.
From GB-A-1 307 127, the use of 85 % by weight of calcium bentonite, 10 ~ by weight of sodium phosphate and 5 % by weight of sodium borate in oil, gas and coal firings may be taken for granted. US-A-3 249 047 proposes the intoduction of antimony compounds and silicates having large specific surfaces in the overheating zone of coal-fired boilers in order to reduce SO3 corrosion.
Finally, GB-A-800 445 suggests to use burnt bentonite and other refractory materials in order to enhance the distribution of oil droplets in gas turbines.
The invention aims at providing a method of the initially defined kind, in which even the slightest amounts of an additive may be employed with alkali and the content of metal chlorides in the smoke gas being reducible as quickly as possible. The reaction is to start as rapidly as possible and to occur even at high temperatures without releasing elementary chlorine.
To solve this object, the method according to the invention for reducing high temperature chlorine corrosion in firing means and incineration plants, wherein additives are nozzled into the gas space, essentially consists in that acidically activated bentonite is nozzled into the gas space at gas temperatures of above 750~C, preferably 800~C. Due to the high reactivity of acidically activated bentonite it is even feasible already at relatively high temperatures to effect the desired reaction for binding alkalis, the desired reactions proceeding rapidly and quantitatively even at temperatures of above 900~C. Very quick alkali binding, therefore, is achieved if the additive is nozzled in along with secondary air closely above the burner plane or the grate, for instance in the plane , of the secondary air supply, so as to be able to substantially reduce the distance over which a corrosive attack may happen at all. In order to enhance the distribution of the acidically activated bentonite, the latter optionally may be nozzled in together with silicon dioxide, SiO2 becoming active primarily as a diluent. In any event, acidically activated bentonite in mixtures with SiO2 is to be used in amounts of more than 50 %
by weight, based on the mixture, in order to rapidly ensure the desired reaction.
By nozzling in glass dust it can be ensured that the glass dust or glass powder will rapidly melt completely, wherein an effective protection of the boiler walls to be proteced against corrosion may be enhanced in that the glass dust or glass powder is introduced in the direction of the walls of the gas space via directed nozzles or spraying discs. In this manner, a rinsing flow of glass melt is safeguarded along the walls of the gas space.
In accordance with the invention, glass dust or glass powder advantageously is nozzled into the gas space in amounts of from 0.3 kg/ton to 30 kg/ton refuse, wherein ground used glass such as, e.g., window glass or bottle glass may simply be used. Advantageously, glass ground to grain sizes of about 50 ~m is used for the method according to the invention.
Advantageously, it is proceeded in a manner that acidically activated bentonite optionally mixed with sio2 is nozzled into refuse incineration plants in amounts of from 0.5 to 3.0 kg/ton refuse.
A particularly economic process control enabling further reduction of pollutant emissions may be achieved in that acidically activated bentonite is used for adsorbing harmful substances such as Hg or dioxin in the cooled offgases of incineration plants, in particular in a flue flow process, and subsequently is nozzled into the combustion chamber.
.. _ . . . ..
Due to the conditions prevailing within the firing chamber, alkaline chloride is formed in quite considerable amounts at the high chlorine contents usually present in refuse these days. The ratio between chlorine and sulfur with refuse in smoke gas has shifted in favor of chlorine during the past years, elevated amounts of metal chlorides getting into the smoke gas undecomposed and being converted into sulfates only there or in the deposits. Under the given thermodynamic conditions such a reaction, which is also called sulfation reaction, results in sodium sulfate and elementary chlorine and hence in a strong corrosive attack. The chlorine even reaches the tube surface and there can destroy steel while forming iron chloride. Such a sulfation reaction in the firing chamber mainly is to be observed behind and closely above the brickwork, and the nozzling in of acidically activated bentonite according to the invention renders feasible an extremely rapid reduction of the metal chloride content.
Proposals to nozzle sulfur into the smoke gas for that purpose bring about an acceleration of chloride sulfation, yet sulfation will occur only at lower temperatures and the amount of released chlorine will be the same. Acidically activated bentonite, due to its chemical and physical properties, is able to react with alkaline compounds in the smoke gas extremely rapidly even at elevated temperatures, in particular at temperatures of above 900~C, wherein alkali can be bound and HCl is formed. Thus, no elementary chlorine is released and the risk of high temperature chlorine corrosion is substantially lowered.
According to the invention, a cost-effective and simple additive to be additionally used for nozzling into the combustion chambers of firing means and refuse incineration plants, which enables boiler campaigns to be substantially increased and which, at the same time, aims to drastically reduce the portion of flue dust contained in the offgas, which is still relatively high in case of known additives, was .. . .
obtained from oxide melts, in particular glass powder or glass dust having a melting point of below 1000~C. Glass powder or glass dust, which preferably is nozzled in in counterflow to the smoke gases, melts at the temperatures prevailing in the combustion chambers, binding flue dust to water insoluble glasses. At the same time, surprisingly also alkali is rapidly bound into such melting glass powder or glass dust particles with a rapid reduction of the chlorine content in the offgases likewise having been observed in a surprising manner. All of these corrosive components of the combustion offgases are, thus, effectively bound by the melting glass powder or glass dust particles with the additional advantage being obtained of the melt forming a dense deposit on the boiler walls, which will prevent corrosive attacks, flowing down along the walls in the direction towards the slag as a liquid melt film. Such a rinse of the boiler walls by the molten glass melt in addition to a corrosion-reducing effect on the boiler walls to be protected, thus, also has the advantage of a number of noxious substances being effectively dischargeable by the downwardly flowing melt. Such an additional additive may be nozzled in along with acidically activated bentonite, thereby enhancing the effects to go even beyond the sum of the individual effects.
Advantageously, glass powder or glass dust having a melting point of below 800~C is used, complete melting and the safe delivery of the noxious matter dissolved in the melt being ensured in'that the glass powder or glass dust has a mean grain size of 30 to 60 ~m, preferably 40 ~m.
In the following, the invention will be explained in more detail by way of two diagrams. In Fig.l of the drawing the amount of sodium chloride as well as the SO2 equilibrium partial pressure are plotted over the temperature for the firing chamber conditions indicated below. PCO2 = 0.2 bar, pH2O = 0.2 bar, PO2 = 0.05 bar, pHCl = 10-5 bar and pCl = 10-5 bar. From that illustration according to Fig. 1 it is apparent , , . . ~
that the formation of sodium chloride in the firing chamber occurs primarily in the high temperature range and it is, therefore, aimed at eliminating sodium chloride from the smoke gas already at high temperatures.
In Fig. 2 the amount of sodium chloride in mg/m3 is plotted over the temperature. Curve 1 indicates the reduction to be attained by nozzling in 1 kg of acidically activated bentonite per ton of refuse. Curve 2 shows the effect that would be achievable by nozzling in 2 kg of sulfur, this clearly illustrating the superiority of nozzling in acidically activated bentonite for the purpose of lowering the sodium chloride portion at high temperatures. On the other hand, Curve 3 clearly shows the effect if only 1 kg of sulfur is nozzled in and Curve 4 indicates the effect with pure smoke gas.
The additive is in powder form and may readily be prepared in a grinding fineness that allows the additive to be nozzled directly into the firing chamber via secondary air.
When simultaneously nozzling in glass, corrosion-resistant linings of the boilers were formed and the pollutant emission was lowered, the service life of the means following upon the firing chamber, such as superheaters or the like, having been improved as well.
Method for Preventinq Hiqh Tem~erature Corrosion The invention relates to a method for preventing high temperature chlorine corrosion in combustion chambers of firing means and waste incineration plants and reducing the flue dust portion contained in the combustion offgases.
Known methods for preventing corrosion were aimed at reducing corrosion in incineration plants and, in particular, on the heat exchanger surfaces of boilers by effecting reactions in the gas phase in order to deactivate corrosive substances. To this end, magnesium oxide is usually nozzled in, thereby enabling primarily high temperature sulfate corrosion to be substantially reduced at temperatures of above 480~C. This is obtained in that, at an excess of MgO contained in the deposits forming, for instance, on the superheater tubes, MgSO4 instead of alkali pyrosulfates is formed with the SO2 of the smoke gas. At temperatures of above 480~C alkali pyrosulfates will, in fact, dissolve the layer of scale, thus leading to catastrophic corrosion damages.
MgO is ineffective against corrosive damages caused by chlorine forming during the sulfation of chlorides.
That type of corrosion has been increasingly encountered in the firing space regions of refuse incineration plants during the past years, since the composition of refuse has changed on account of refuse separation, on the one hand and a higher smoke gas temperature must be observed as in accordance with legal provisions, on the other hand (800~C for at least 2 seconds within the combustion chamber).
From WO 95/11287 it has already become known to nozzle cerium compounds such as iron cerium, cerium oxides and/or cerium oxide hydrates in powder form. According to that previous proposal, it was possible to nozzle in such cerium compounds together with magnesium oxide, primarily aiming at substantially reducing the cleaning expenditures involved in the removal of deposits from the internal sides of plant parts and thereby enabling longer campaign times than in known processes. In particular, it was intended to preserve the action of, and no longer deteriorate, passivating layers already formed on the upper surfaces of plant parts for the protection of the same. Those cerium compounds such as iron cerium, cerium oxide or cerium oxide hydrate were to safeguard reducing zones in the vicinity of the walls in order to thereby reduce corrosion. The effect of cerium compounds in the manner of oxidation catalysts induces afterburning in reducing regions of the smoke gas, thereby reliably preventing the reduction of an oxide layer of scale or rust already formed for passivation. The cerium compounds also were to become active against chloride ion corrosion in order to thereby ensure oxidation to basically less dangerous chlorine gas in molecular form.
The use of additives of this type, however, involves relatively high costs and has proved to be insufficiently effective, in particular in connection with high temperature chlorine corrosion, in which chlorine gases dissociate again.
Attempts to admix to the charging material to be burnt filtering aids and, in particular, inorganic filtering aids based on active silicic acid containing silanol groups likewise have proved to be relatively expensive, since additives will show effects only in percentage ranges due to their being inhomogenously distributed in refuse.
For recycling into the circuit of a melting chamber firing means pollutant-loaded residues such as, for instance, filter ashes, adsorbents or the like while adding used glass and/or limestone chips, DE-A-4 021 362 has already proposed to introduce the absorber into the circuit of a melting chamber firing means with complete ash recycling. The absorber may be fed into the the smoke gas path and/or into the ash recirculation and/or into the slag discharge and/or along with coal, wherein broken used glass and/or limestone chips may be dosed in.
From GB-A-1 307 127, the use of 85 % by weight of calcium bentonite, 10 ~ by weight of sodium phosphate and 5 % by weight of sodium borate in oil, gas and coal firings may be taken for granted. US-A-3 249 047 proposes the intoduction of antimony compounds and silicates having large specific surfaces in the overheating zone of coal-fired boilers in order to reduce SO3 corrosion.
Finally, GB-A-800 445 suggests to use burnt bentonite and other refractory materials in order to enhance the distribution of oil droplets in gas turbines.
The invention aims at providing a method of the initially defined kind, in which even the slightest amounts of an additive may be employed with alkali and the content of metal chlorides in the smoke gas being reducible as quickly as possible. The reaction is to start as rapidly as possible and to occur even at high temperatures without releasing elementary chlorine.
To solve this object, the method according to the invention for reducing high temperature chlorine corrosion in firing means and incineration plants, wherein additives are nozzled into the gas space, essentially consists in that acidically activated bentonite is nozzled into the gas space at gas temperatures of above 750~C, preferably 800~C. Due to the high reactivity of acidically activated bentonite it is even feasible already at relatively high temperatures to effect the desired reaction for binding alkalis, the desired reactions proceeding rapidly and quantitatively even at temperatures of above 900~C. Very quick alkali binding, therefore, is achieved if the additive is nozzled in along with secondary air closely above the burner plane or the grate, for instance in the plane , of the secondary air supply, so as to be able to substantially reduce the distance over which a corrosive attack may happen at all. In order to enhance the distribution of the acidically activated bentonite, the latter optionally may be nozzled in together with silicon dioxide, SiO2 becoming active primarily as a diluent. In any event, acidically activated bentonite in mixtures with SiO2 is to be used in amounts of more than 50 %
by weight, based on the mixture, in order to rapidly ensure the desired reaction.
By nozzling in glass dust it can be ensured that the glass dust or glass powder will rapidly melt completely, wherein an effective protection of the boiler walls to be proteced against corrosion may be enhanced in that the glass dust or glass powder is introduced in the direction of the walls of the gas space via directed nozzles or spraying discs. In this manner, a rinsing flow of glass melt is safeguarded along the walls of the gas space.
In accordance with the invention, glass dust or glass powder advantageously is nozzled into the gas space in amounts of from 0.3 kg/ton to 30 kg/ton refuse, wherein ground used glass such as, e.g., window glass or bottle glass may simply be used. Advantageously, glass ground to grain sizes of about 50 ~m is used for the method according to the invention.
Advantageously, it is proceeded in a manner that acidically activated bentonite optionally mixed with sio2 is nozzled into refuse incineration plants in amounts of from 0.5 to 3.0 kg/ton refuse.
A particularly economic process control enabling further reduction of pollutant emissions may be achieved in that acidically activated bentonite is used for adsorbing harmful substances such as Hg or dioxin in the cooled offgases of incineration plants, in particular in a flue flow process, and subsequently is nozzled into the combustion chamber.
.. _ . . . ..
Due to the conditions prevailing within the firing chamber, alkaline chloride is formed in quite considerable amounts at the high chlorine contents usually present in refuse these days. The ratio between chlorine and sulfur with refuse in smoke gas has shifted in favor of chlorine during the past years, elevated amounts of metal chlorides getting into the smoke gas undecomposed and being converted into sulfates only there or in the deposits. Under the given thermodynamic conditions such a reaction, which is also called sulfation reaction, results in sodium sulfate and elementary chlorine and hence in a strong corrosive attack. The chlorine even reaches the tube surface and there can destroy steel while forming iron chloride. Such a sulfation reaction in the firing chamber mainly is to be observed behind and closely above the brickwork, and the nozzling in of acidically activated bentonite according to the invention renders feasible an extremely rapid reduction of the metal chloride content.
Proposals to nozzle sulfur into the smoke gas for that purpose bring about an acceleration of chloride sulfation, yet sulfation will occur only at lower temperatures and the amount of released chlorine will be the same. Acidically activated bentonite, due to its chemical and physical properties, is able to react with alkaline compounds in the smoke gas extremely rapidly even at elevated temperatures, in particular at temperatures of above 900~C, wherein alkali can be bound and HCl is formed. Thus, no elementary chlorine is released and the risk of high temperature chlorine corrosion is substantially lowered.
According to the invention, a cost-effective and simple additive to be additionally used for nozzling into the combustion chambers of firing means and refuse incineration plants, which enables boiler campaigns to be substantially increased and which, at the same time, aims to drastically reduce the portion of flue dust contained in the offgas, which is still relatively high in case of known additives, was .. . .
obtained from oxide melts, in particular glass powder or glass dust having a melting point of below 1000~C. Glass powder or glass dust, which preferably is nozzled in in counterflow to the smoke gases, melts at the temperatures prevailing in the combustion chambers, binding flue dust to water insoluble glasses. At the same time, surprisingly also alkali is rapidly bound into such melting glass powder or glass dust particles with a rapid reduction of the chlorine content in the offgases likewise having been observed in a surprising manner. All of these corrosive components of the combustion offgases are, thus, effectively bound by the melting glass powder or glass dust particles with the additional advantage being obtained of the melt forming a dense deposit on the boiler walls, which will prevent corrosive attacks, flowing down along the walls in the direction towards the slag as a liquid melt film. Such a rinse of the boiler walls by the molten glass melt in addition to a corrosion-reducing effect on the boiler walls to be protected, thus, also has the advantage of a number of noxious substances being effectively dischargeable by the downwardly flowing melt. Such an additional additive may be nozzled in along with acidically activated bentonite, thereby enhancing the effects to go even beyond the sum of the individual effects.
Advantageously, glass powder or glass dust having a melting point of below 800~C is used, complete melting and the safe delivery of the noxious matter dissolved in the melt being ensured in'that the glass powder or glass dust has a mean grain size of 30 to 60 ~m, preferably 40 ~m.
In the following, the invention will be explained in more detail by way of two diagrams. In Fig.l of the drawing the amount of sodium chloride as well as the SO2 equilibrium partial pressure are plotted over the temperature for the firing chamber conditions indicated below. PCO2 = 0.2 bar, pH2O = 0.2 bar, PO2 = 0.05 bar, pHCl = 10-5 bar and pCl = 10-5 bar. From that illustration according to Fig. 1 it is apparent , , . . ~
that the formation of sodium chloride in the firing chamber occurs primarily in the high temperature range and it is, therefore, aimed at eliminating sodium chloride from the smoke gas already at high temperatures.
In Fig. 2 the amount of sodium chloride in mg/m3 is plotted over the temperature. Curve 1 indicates the reduction to be attained by nozzling in 1 kg of acidically activated bentonite per ton of refuse. Curve 2 shows the effect that would be achievable by nozzling in 2 kg of sulfur, this clearly illustrating the superiority of nozzling in acidically activated bentonite for the purpose of lowering the sodium chloride portion at high temperatures. On the other hand, Curve 3 clearly shows the effect if only 1 kg of sulfur is nozzled in and Curve 4 indicates the effect with pure smoke gas.
The additive is in powder form and may readily be prepared in a grinding fineness that allows the additive to be nozzled directly into the firing chamber via secondary air.
When simultaneously nozzling in glass, corrosion-resistant linings of the boilers were formed and the pollutant emission was lowered, the service life of the means following upon the firing chamber, such as superheaters or the like, having been improved as well.
Claims (5)
1. A method for preventing high temperature corrosion and reducing the portion of flue dust contained in the combustion offgases of firing means and waste incineration plants, characterized in that acidically activated bentonite is nozzled into the gas space at gas temperatures of above 750°C, preferably 800°C.
2. A method according to claim 1, characterized in that acidically activated bentonite in mixtures with SiO2 is nozzled in, the portion of acidically activated bentonite being larger than 50 % by weight, based on the mixture.
3. A method according to claim 1 or 2, characterized in that acidically activated bentonite optionally mixed with SiO2 is nozzled into refuse incineration plants in amounts of from 0.5 to 3.0 kg/ton refuse.
4. A method according to any one of claims 1, 2 or 3, characterized in that ground used glass such as, e.g., window glass or bottle glass is used as SiO2 component.
5. A method according to any one of claims 1 to 4, characterized in that acidically activated bentonite is used for adsorbing harmful substances such as Hg or dioxin in the cooled offgases of incineration plants, in particular in a flue flow process, and subsequently is nozzled into the combustion chamber.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT129496A AT405741B (en) | 1996-07-18 | 1996-07-18 | Additive for preventing high temperature chlorine corrosion, its production and the reduction of high temperature chlorine corrosion in firing and combustion plant |
| ATA1294/96 | 1996-07-18 | ||
| ATA194/97 | 1997-02-07 | ||
| AT19497A AT404136B (en) | 1997-02-07 | 1997-02-07 | Additive for spraying into combustion chambers of furnaces and waste incineration plants and also a method of preventing high-temperature corrosion |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2261037A1 true CA2261037A1 (en) | 1998-01-29 |
Family
ID=25591809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002261037A Abandoned CA2261037A1 (en) | 1996-07-18 | 1997-07-09 | Additive to be sprayed into the combustion chambers of heating plants and process for preventing high temperature corrosion |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0958335B1 (en) |
| AT (1) | ATE201226T1 (en) |
| AU (1) | AU3328597A (en) |
| CA (1) | CA2261037A1 (en) |
| DE (1) | DE59703573D1 (en) |
| DK (1) | DK0958335T3 (en) |
| WO (1) | WO1998003616A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8198208B2 (en) | 2008-10-03 | 2012-06-12 | EPCOR Power Generation Services, Inc. | Bromination process |
| CN103127806A (en) * | 2013-02-07 | 2013-06-05 | 中国恩菲工程技术有限公司 | Device used for disposing incineration fly ash |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT502619B1 (en) | 2004-10-04 | 2010-01-15 | Ica Chemie Ag | PROCESS FOR PREVENTING HIGH-TEMPERATURE CHLORINE CORROSION IN COMBUSTION PLANT |
| FI117631B (en) | 2005-06-16 | 2006-12-29 | Valtion Teknillinen | A method of preventing the deposition of chlorine on the heating surfaces of a boiler |
| US8408148B2 (en) | 2006-03-31 | 2013-04-02 | Atlantic Combustion Technologies Inc. | Increasing the efficiency of combustion processes |
| FI20075891L (en) * | 2007-12-10 | 2009-06-11 | Metso Power Oy | Method for preventing corrosion of heat transfer surfaces in a boiler, and means for introducing an additive |
| CN102786998B (en) * | 2012-07-24 | 2014-04-02 | 周丽琴 | Boiler coke preventing and eliminating agent |
| BR112016015494B1 (en) | 2014-01-07 | 2022-03-08 | Imerys Ceramics France | METHOD FOR COMBUSTION OF RESIDUAL MATERIAL |
| AT516407B1 (en) | 2014-11-20 | 2016-05-15 | Andritz Ag Maschf | Process for the use of hydrated sorbents in thermal process plants |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB800445A (en) * | 1956-08-17 | 1958-08-27 | Exxon Research Engineering Co | Improved fuel for use in gas turbine plants |
| GB939938A (en) * | 1960-02-29 | 1963-10-16 | Fullers Earth Union Ltd | Improvements in or relating to activated earths |
| NL292134A (en) * | 1963-02-16 | 1900-01-01 | ||
| US3249075A (en) * | 1963-03-08 | 1966-05-03 | Combustion Eng | Additive mixtures to combat high temperature corrosion and ash bonding during the operation of furnaces |
| GB1288806A (en) * | 1968-10-01 | 1972-09-13 | ||
| GB1307127A (en) * | 1970-09-25 | 1973-02-14 | Milner M R | Combustion adjuvant |
| DE2944989A1 (en) * | 1979-11-07 | 1981-05-21 | Deutsche Kommunal-Anlagen Miete GmbH, 8000 München | Purificn. of gases from pyrolysis of wastes - with reduced pollution from disposal of used absorbents |
| DE3855248D1 (en) * | 1987-05-18 | 1996-06-05 | Ftu Gmbh | USE OF REACTIVE CALCIUM HYDROXIDE FOR GAS AND EXHAUST GAS PURIFICATION AND |
| DE4012982A1 (en) * | 1990-04-24 | 1991-10-31 | Ftu Gmbh | Removing harmful (in)organic substance from gases - by addn. of finely divided substance with active surface and filtration |
| DE4021362A1 (en) * | 1990-07-05 | 1992-01-09 | Siemens Ag | Disposal of solids loaded with pollutants - in slagging furnace with total ash recycle |
| DE4034498A1 (en) * | 1990-09-06 | 1992-03-12 | Metallgesellschaft Ag | METHOD FOR SEPARATING HEAVY METALS AND DIOXINES FROM COMBUSTION EXHAUST GASES |
-
1997
- 1997-07-09 AU AU33285/97A patent/AU3328597A/en not_active Abandoned
- 1997-07-09 DK DK97929019T patent/DK0958335T3/en not_active Application Discontinuation
- 1997-07-09 WO PCT/AT1997/000158 patent/WO1998003616A1/en active IP Right Grant
- 1997-07-09 AT AT97929019T patent/ATE201226T1/en active
- 1997-07-09 DE DE59703573T patent/DE59703573D1/en not_active Expired - Lifetime
- 1997-07-09 CA CA002261037A patent/CA2261037A1/en not_active Abandoned
- 1997-07-09 EP EP97929019A patent/EP0958335B1/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8198208B2 (en) | 2008-10-03 | 2012-06-12 | EPCOR Power Generation Services, Inc. | Bromination process |
| CN103127806A (en) * | 2013-02-07 | 2013-06-05 | 中国恩菲工程技术有限公司 | Device used for disposing incineration fly ash |
| CN103127806B (en) * | 2013-02-07 | 2016-02-24 | 中国恩菲工程技术有限公司 | For the treatment of the equipment of flying ash |
Also Published As
| Publication number | Publication date |
|---|---|
| DE59703573D1 (en) | 2001-06-21 |
| EP0958335A1 (en) | 1999-11-24 |
| EP0958335B1 (en) | 2001-05-16 |
| DK0958335T3 (en) | 2001-08-20 |
| ATE201226T1 (en) | 2001-06-15 |
| AU3328597A (en) | 1998-02-10 |
| WO1998003616A1 (en) | 1998-01-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |