CA2258943A1 - Process for treating waste gases arising in a combustion facility for organic gases - Google Patents

Process for treating waste gases arising in a combustion facility for organic gases Download PDF

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Publication number
CA2258943A1
CA2258943A1 CA 2258943 CA2258943A CA2258943A1 CA 2258943 A1 CA2258943 A1 CA 2258943A1 CA 2258943 CA2258943 CA 2258943 CA 2258943 A CA2258943 A CA 2258943A CA 2258943 A1 CA2258943 A1 CA 2258943A1
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CA
Canada
Prior art keywords
waste
facility
process according
gases
waste gases
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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.)
Abandoned
Application number
CA 2258943
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French (fr)
Inventor
Heinz Holter
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Individual
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Individual
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Publication date
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Priority to CA 2258943 priority Critical patent/CA2258943A1/en
Publication of CA2258943A1 publication Critical patent/CA2258943A1/en
Abandoned legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23GCREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G7/00Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
    • F23G7/06Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23CMETHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2202/00Fluegas recirculation
    • F23C2202/10Premixing fluegas with fuel and combustion air

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  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

The invention concerns a process for treating waste gases which contain organic pollutant compounds and are produced in waste-incinceration plants. Without being pre-treated, the waste gases are mixed with hot flue gases from the fossil fuel-burning furnaces of industrial boiler plants and so heated to above 1200°C.

Description

Process for Treating Waste Gases Arising in a Combustion Facility for Organic Gases The invention concerns a process for treating waste gases arising in a combustion facility for wastes containing toxic organic compounds.
A series of processes in the area of pyrolysis, gasification and in particular of the combustion of wastes for thermal processing of organic waste substances such as, for example, household and/or commercial garbage, have become known.
In practice, thermal waste processing chiefly takes place now in combustion facilities, and in particular in combustion facilities outfitted with a grate firing.
The waste gases arising in these facilities are subjected to dust separation, desulfurization and usually also to denitrification similar to the flue gases from fossil firings of industrial boiler facilities, such as, for example, coal power plants.
In this connection, it is a disadvantage that organic hydrocarbon compounds usually still contained in me waste gases from waste combustion facilities owing to the inhomogeneous composition of the waste, among them highly toxic furans and dioxins, are not picked up by the cleansing facilities mentioned, or lead to a contamination of the separated flue dust. In addition to impairing dust processing, it is thus necessary to provide additional, generally very expensive separation facilities (usually activated charcoal facilities) in waste combustion facilities to separate the hydrocarbon compounds still present in the waste gas.
Underlying the invention is the object of significantly reducing the technical and economic expense of the separation of toxic hydrocarbon compounds from waste gases of trash burning facilities.
This object is reached in accordance with the invention via with a process of the abovementioned type in that the waste gases are mixed, without previous separation of toxic substances, with hot flue gases from the fossil firing of one or more industrial boiler facilities and then heated to a temperature > 1200° C.
The organic compounds still contained in the waste gas are either afterburned or even cleaved through the heating of the waste gases of a trash burning facility to temperatures above 1200° C of the invention. As experiments have shown, highly toxic dioxins and furans are no longer detectable in the flue gas of fossil industrial boiler facilities to which the waste gas of the combustion facility was admixed. At the same time it has surprisingly also become apparent that neither dioxins nor furans form again when the flue gas is cooled.
The admixed waste gases from trash burning facilities can henceforth be subjected to the usual toxic substance separation (dust removal, desulfurization, denitrification) and then be dissipated into the atmosphere.
According to a further feature of the process of the invention, it proves to be especially advantageous to admix the combustion facility waste gases to, the hot flue gas of the furnace of a cement facility.
With flue gas temperatures in the cement facility of up to 2000°
C, it will henceforth create no problems of any kind to heat the waste gases from the trash burning facility as well up to the required temperature of 1200°
C.
Secondly, and herein lies a special economic advantage, the heat content even of untreated, that is, not prepared waste, can be directly used in a cement facility.
While with previous methods for the joint use of waste as a fuel in cement facilities, the waste was directly admixed with the operating fuel (which imposes very high standards on the quality of waste preparation and basically permits only the use of about 30% of the waste arising in order to avoid processing engineering-related impairment of cement manufacture). Now a complete disconnection of the combustion of waste and fossil fuel is taking place in the area of the cement facility. The heat content of the waste is henceforth being inj ected into the cement manufacturing process through the hot waste gas, which as a rule permits temperatures between 800 and 1000° C
in trash burning facilities. The residues arising from waste combustion, as for example, the preponderant part of slag, thereby remain in the trash burning facility and cannot prove to be harmful in respect to, the operating parameters to be maintained in cement production.
Appropriately, the waste gas arising in the waste combustion facility is here admixed directly to the furnace air required for fossil firing of the cement facility. In this way, a homogenous mixture of waste gas and flue gas is guaranteed directly behind the burner.
Of course, the waste gas can also be directly introduced into the cement furnace at an appropriate place.
According to a further feature of the process of the invention, it also proves practical in connection with cement facilities to use the hot cooling air from the clinker cooler as furnace air for the waste combustion facility.
Owing to the high temperature of exhaust air from the clinker cooler of approx.
800°
C, optimal firing conditions are herewith created in the trash burning facility. In the event that the waste combustion facility is to be operated under reducing conditions, that is, as a waste gasification facility, at least one part of the heat required for the gasification can also be injected from the hot flue gas of the cement furnace. In this case, the waste gas from the trash burning facility still contains chemically bound heat which is released by combustion in the cement furnace.
The residues arising in waste combustion or gasification can be used in the usual manner, for example for road construction and building or, however, in prepared form, for the cement process itself as additives.
According to a further feature of the invention, the hot waste gas of the trash combustion facility can also appropriately be admixed to the even hotter flue gas of a coal power plant. With coal-fired power plants with coal dust firing as well as with melt firing, thus with dry as well as in connection with wet-deslagged coal-fired boilers, the temperature level of the flue gas arising is sufficient for attaining the minimum temperature of 1200° C requisite for eliminating toxic hydrocarbon compounds, such as dioxins and furans, for example, after mixing with the waste gas of trash burning facilities.
Appropriately, in this connection the waste gas from the trash burning facility is admitted to the lower area of the boiler of the coal-fired power plant, due to which particularly long holding times and consequently heating times of the waste gas are attained in the coal-fired boiler.
In coal-fired power to which a trash burning facility is being retroactively connected up on the waste gas end as a so-called satellite facility, it may also prove to be appropriate to admix the waste gases from the waste combustion facility directly to the furnace air for the coal burner of the coal-fired boiler and to feed it with these into the power plant boiler.
It is also possible, however, to introduce the waste gases from the trash burning facility into the boiler together with the fresh coal over the grinding-drying facility. This method has the further advantage that thereafter the heat content of the hot waste gases from the trash burning facility can be used for drying the fresh coal.
Further variants for introducing the waste gases from trash burning facilities into the boiler of the coal power plant are: introducing them into the coal drop chute of the coal grinder, into the return feed shaft of the flue gas used for grinding-drying, thus before the coal grinder, as well as in connection with grinder air compressors present in the air duct in front of or behind the grinder air duct.
In the event that, due to the existing infrastructure, the trash burning facility can only be erected at a great distance from the power plant boiler, it may also prove appropriate to cool the hot flue gases of the waste gases, for example in direct or indirect heat exchange with furnace air for the coal-fired boiler, to the extent that an expensive brick lining of the waste gas connection conduit between the trash burning facility and the power plant boiler can be dispensed with.
It also proves appropriate according to a further feature of the process of the invention to separate the waste intended for the waste combustion facility into a coarse fraction richer in heat value which is then fed into the combustion facility, and into a fine fraction poorer in heat value which is first subjected to a steeping process and subsequently burned together with fossil fuel in an industrial boiler, preferably a coal-fired power plant boiler.
In particular, household waste, for example, is separated by a trommel revolving screen with a cross section of ca. ~ 40 mm into a fraction rich in heat value and into a fraction poor in heat value. The latter contains much organic material with great moisture (food residues) and largely inert fine waste. The fraction rich in heat value consists to a large part of wood, cardboard, paper, foils, textiles, and is contaminated with coarse impurities.
The fraction rich in heat value is burned either directly or after transportation with the press container in grate firing after sorting out the largest impurities and running through magnetic separation. Transport in press balls is also possible, for which, of course, a crushing process is also necessary.
The flue gas of grate firing is also conducted to the coal-fired large boiler and passes through the boiler together with the flue gas from its firing. Harmful substances are destroyed or vaporized owing to the high combustion chamber temperatures of far above 1200° C and separated by condensation or sublimation on flue dust together with this in a filter or washer.
The fraction poor in heat value is transformed into a biologically stable state in an intensive steeping, whereby a steeping loss by carbon dioxide and water vapor of about 30% arises. The steeped material is not pathogenic, its odor is minor, and its residual moisture amounts to 10- 15%. The formation of _7_ gas deposits and seepage water are minimized and the material can be used for constructing deposits, covering deposits, or for soil amelioration in certain areas. Even in this material about 30% heat value-rich substance is still present, which can be separated by sieving at about 40 ~ 20 mm. In accordance with the invention, the fraction so obtained is conducted directly, [or] with container or press ball transport, to a coal-fired power plant, for example, placed together with the intended fuel into the grinder-dryer, and subsequently burned in the large boiler.
Altogether, about 55% of household waste is thermally processed with high power plant efficiency with the process variants of the invention. A
remaining residue of about 25% is a gassed out, seepage water-poor material suited for building deposits. The remaining 20% represents the steeping loss.
The quality of the steeped material allows improving the quality of the steepage material on compost quality in setting up a resteeping, which considerably expands the area of application as a soil improver.

Claims (12)

1. Process for treating waste gases arising in a combustion facility for wastes which contain harmful organic compounds, characterized in that the waste gases are mixed with hot flue gases from the fossil firing of one or more industrial boiler facilities without prior separation of harmful substances, and thereby heated to a temperature > 1200° C.
2. Process according to claim 1, characterized in that the waste gases are admixed with the hot flue gases of a cement facility.
3. Process according to claim 2, characterized in that the hot waste gases are admixed with the furnace air required for the furnaces of the cement facility, and are introduced into the furnace with this.
4. Process according to claims 3 or 4, characterized in that at least one part of the hot cooling air arising in the clinker cooler of the cement facility is fed as furnace air to the firing of the waste combustion facility.
5. Process according to claim 1, characterized in that the waste gases of the waste combustion facility are admixed with the hot flue gases of a coal-fired power plant.
6. Process according to claim 5, characterized in that the waste gases are introduced into the lower region of the power plant boiler.
7. Process according to claim 6, characterized in that the waste gases are admixed to the furnace air for the coal burners and fed with this into the power plant boiler.
8. Process according to claim, 5, characterized in that the waste gases are introduced into the power plant boiler together with the fresh coal.
9. Process according to claim 8, characterized in that the waste gases are introduced into the power plant boiler through the grinding-drying facility for the fresh coal.
10. Process according to one of claims 1 to 9, characterized in that the waste intended for the combustion facility is separated into a coarse fraction rich in heat value which is led to the waste combustion facility, and into a fine fraction poor in heat value which is first subjected to a steeping process and subsequently burned in an industrial boiler facility together with the fossil fuel intended for the boiler facility.
11. Process according to claim 10, characterized in that the fine fraction is fed out of the steeping process to the coal grinder of a coal-fired power plant or other fossil-fired industrial boiler.
12. Process according to one of claims 10 or 11, characterized in that the coarse fraction has a grain size preferably between 60 and 140 mm and the finer fraction has a grain size chiefly < 60 mm.
CA 2258943 1999-01-14 1999-01-14 Process for treating waste gases arising in a combustion facility for organic gases Abandoned CA2258943A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA 2258943 CA2258943A1 (en) 1999-01-14 1999-01-14 Process for treating waste gases arising in a combustion facility for organic gases

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA 2258943 CA2258943A1 (en) 1999-01-14 1999-01-14 Process for treating waste gases arising in a combustion facility for organic gases

Publications (1)

Publication Number Publication Date
CA2258943A1 true CA2258943A1 (en) 2000-07-14

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2258943 Abandoned CA2258943A1 (en) 1999-01-14 1999-01-14 Process for treating waste gases arising in a combustion facility for organic gases

Country Status (1)

Country Link
CA (1) CA2258943A1 (en)

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