Classifications

• • 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
  • F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
  • F23G5/027—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
  • F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
  • F23C6/045—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure
• • 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
  • F23G5/50—Control or safety arrangements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
  • F23L7/002—Supplying water
  • F23L7/005—Evaporated water; Steam
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel 
  • F23L9/04—Passages or apertures for delivering secondary air for completing combustion of fuel  by discharging the air beyond the fire, i.e. nearer the smoke outlet
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
  • F23C2900/06041—Staged supply of oxidant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2900/00—Special features of, or arrangements for incinerators
  • F23G2900/00001—Exhaust gas recirculation

Definitions

• the present invention relates to a method in which a solid fuel with often heterogeneous properties, preferably waste or biomass, is burned under conditions which reduce or suppress the formation of nitrogen oxides.
• Nitrogen oxides are an undesirable product in the environment and especially after combustion processes. Therefore, a considerable amount of process engineering effort is usually made to prevent the nitrogen oxides generated in the process by means of a complex flue gas aftertreatment.
• the method of staged combustion was introduced, especially for liquid, gaseous and dusty fuels. It is achieved by air gradation or targeted air distribution between primary, secondary and possibly tertiary air that in a first combustion section through substoichiometric operation the precursor substances of fuel NOx are reduced to N 2 (see, for example, US Pat. No. 5,626,085 or US Pat. No. 4,704,084). The course of the reaction is very complex and not completely clarified.
• the unburned substance CO (product of incomplete combustion) also present in this area can also reduce NO to N 2 (simplified: 2 CO 4- 2 NO ⁇ -2 C0 2 + N 2 ) the reacting process gases are mixed intimately to enable the reaction.
• the object of the present invention is to provide a method for primarily solid, also inhomogeneous fuels, in which the formation of nitrogen oxides is largely avoided or at least reduced.
• This object is achieved by the provision of a process which comprises a gradation of the air addition in order to achieve a reaction atmosphere which is first under and then above stoichiometric and the subsequent or accompanying aftertreatment of the flue gases with a catalyst which improves and accelerates the reactions taking place and thus the formation inert nitrogen.
• FIG. 1 schematically shows the air grading and catalyst task in a combustion method according to the present invention on an exemplary combustion system.
• the invention provides that, on the one hand, the staged combustion previously used for liquid and other homogeneous fuels is also used for heterogeneous fuels such as waste or biomass, which, in addition to the problem that is predetermined by the inhomogeneity, is frequently very heavily loaded with nitrogenous substances are. This should largely avoid or completely suppress the formation of nitrogen oxide.
• a suitable catalyst to an area of the incineration plant, which, viewed in the direction of flow, does not lie in front of the incineration area with oxygen present in excess of stoichiometry, ensures that, on the one hand, the amount of air provided for the over-stoichiometric incineration from a possible pulse addition in the Combustion chamber is independent and on the other hand there is still enough oxygen to burn out the unburned substances.
• the gradation of the addition of air ensures that the solid in the combustion chamber is converted to near to clearly under-stoichiometric (controlled gasification through close or under-stoichiometric additions of air in the primary air area).
• the formation of uncontrolled temperature peaks in the combustion chamber is suppressed. Due to the process, larger amounts of unburned substances (eg CO, C ⁇ H y , aromatics, etc.) are produced.
• the precursor substances (eg HCN, amines) of the nitrogen oxides also belong to these substances.
• Already formed NO can react in this area on contact with CO to CO 2 and N 2 , since the oxygen affinity of carbon is greater than that of nitrogen.
• portions of a catalyst which is present as a solid and which is preferably finely divided and / or has a high surface area are additionally added to the flue gas.
• the catalyst to be used according to the invention is able to release non-gaseous excess oxygen in contact reactors to gaseous substances and then to regenerate it again.
• the gaseous substances are preferably oxidizable substances, in particular, for example, C x H y (hydrocarbons), carbon monoxide, but it can also be used to oxidize toxins which are difficult to degrade, such as PCBs, dioxins or furans.
• Suitable for the purposes of the present invention are, for example, ferro-oxide catalysts, for example finely dispersed iron oxide.
• the addition can take place together with the secondary air and / or possibly additionally injected tertiary air.
• the catalyst can also be blown in in other ways, for example with recirculated flue gas or with steam. It is also possible to inject into another area of the combustion chamber or the boiler further back in the flow direction at a lower temperature.
• the person skilled in the art will readily select the suitable variant taking into account the given process conditions. It is essential that the catalyst only after a certain minimum residence time
• an additional impulse is impressed on the flue gas in the combustion chamber. This can be done, for example, by feeding recirculated flue gas or pressurized water vapor or similar media through suitably arranged nozzles.
• Process steps are known for example from DE 196 19 764 AI from Hoechst AG or WO 93/07422 from VAW Aluminum AG. This measure creates turbulence regardless of the introduction of additional oxygen, as a result of which incompletely burned substances such as CO and NO come into better contact with one another and can react to form N 2 and C0 2 .
• the precursors of nitrogen oxides are also reduced to a high degree to N 2 in this area, which is characterized by a substoichiometric atmosphere. Nitrogen oxides that are still formed can be reduced to N 2 as described above.
• additional mixing impulses can also be introduced into the combustion gases in the transition from the combustion chamber to the combustion chamber or freeboard, for example by recirculated flue gas or steam. This procedure is also known from the prior art, see e.g. DE 44 02 172 AI.
• the addition of primary air can be controlled in such a way that certain temperature targets (eg temperature below the ash softening point) are maintained in or on the combustion bed. These temperature targets can be monitored by suitable temperature measuring devices, for example using an infrared ka era. In addition, the gas atmosphere and in particular the oxygen content can be monitored by suitable measuring instruments.
• temperature targets eg temperature below the ash softening point
• suitable temperature measuring devices for example using an infrared ka era.
• the gas atmosphere and in particular the oxygen content can be monitored by suitable measuring instruments.
• a combustion process is shown in which a fuel such as garbage 1 is added.
• the fuel is pushed into the combustion chamber 3 by a feed slide 2.
• the fuel is combusted or gasified under the supply of primary combustion air 4.
• Temperature monitoring and control of the air distribution is carried out with the help of an infrared camera 5, e.g. on the rear wall of the combustion chamber.
• the gasification products rising from the solid bed can be intimately mixed by the targeted addition of recirculated flue gas 6 or the like.
• additional combustion air secondary air 8 or tertiary air 9
• the afterburning of the unburned substances from the combustion chamber is achieved.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Incineration Of Waste (AREA)
• Solid-Fuel Combustion (AREA)
• Gasification And Melting Of Waste (AREA)
• Catalysts (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7660258

Family Applications (1)

Country Status (6)

Families Citing this family (6)

Family Cites Families (12)

• 2000
  • 2000-10-18 DE DE10051733A patent/DE10051733B4/de not_active Expired - Fee Related
• 2001
  • 2001-10-17 EP EP01983559A patent/EP1327104B1/fr not_active Expired - Lifetime
  • 2001-10-17 JP JP2002536463A patent/JP2004511750A/ja active Pending
  • 2001-10-17 WO PCT/EP2001/012029 patent/WO2002033317A1/fr active IP Right Grant
  • 2001-10-17 DE DE50108574T patent/DE50108574D1/de not_active Expired - Lifetime
  • 2001-10-17 AT AT01983559T patent/ATE314613T1/de not_active IP Right Cessation
  • 2001-10-17 KR KR10-2003-7005356A patent/KR20030046512A/ko not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events