DE4103025A1 - METHOD FOR TEMPERATURE REGULATION IN WASTE COMBUSTION PLANTS - Google Patents

Description

The invention relates to a method for temperature regulation of combustion in gradual combustion in waste incineration plants.

The steadily increasing amount of waste and the fact that numerous landfills are now reaching their capacity limits have achieved lead to the establishment and the Operation of waste incineration plants more and more forced becomes. The immissions from waste incineration should be through the in the Federal Immission Control Ordinance prescribed measures reduced to a minimum will.

So the 17th Federal Immission Control Ordinance calls for Compliance with a flue gas temperature of 850 ° C for one Flow time of 2 seconds from the last air nozzle in the boiler. At an average smoke gas velocity of 5 m / sec. this corresponds to one required smoke gas temperature of 850 ° C still 10 m above half of the last air supply. With favorable advance Settlement is at this distance with a temperature degradation of 150 ° C, so that in the area of the last Air supply temperature of 1000 ° C and higher prevail got to. The combustion of the waste incineration plants must then reach an internal temperature of 1000 ° C. The same early demand for trouble-free operation of the furnace makes heat dissipation in the furnace over water cooled fire rooms necessary. The allowable cladding strength through refractory material is very limited. In to  Heavy cladding can cause unwanted firing and form disturbing wall approaches. If too small eng cladding will ensure compliance with the required smoke gas temperature difficult. When operating on layers are fire outlet if operation is free of charge temperatures of <850 ° C due to the resulting beam high heat dissipation in the combustion chamber of up to 30% of the total heat hardly attainable.

The technical problem of the invention is therefore to reduce the heat reduction by radiation at the same time early avoidance of build-up in the furnace and shifting the heat content over a larger smoke volume of gas into the convection heating surface of the boiler. These Measures should lead to the fact that the Federal immission protection regulation required compliance with Flue gas temperature of 850 ° C with a duration of 2 seconds from the last air injection is observed.

The technical problem of the invention is solved by that 10 to 30 vol .-% of the total flue gas recirculates and directly into the furnace above the garbage bed will blow.

In a preferred embodiment, the flue gas after flowing through the boiler and a first Cleaning stage recirculated. The recirculation can be done with a fire optimization scheme in coordination with the gradual combustion can be regulated.

Furthermore, it is preferred that the flue gases on all sides be blown into the furnace. The blowing can over the grate length above the side wall panels and over the grate width by means of separate nozzles in the Se secondary air beams are made.  

In a preferred embodiment, the openings nozzles of the flue gas supply in horizontal and vertical Slope changeable. Furthermore, to achieve a sufficient depth of penetration the opening nozzles of the smoke gas supply as square or circular nozzles be trained, the free cross section change by de missions is changeable. In total there are about up to ten openings are provided on each side. This is the free one Flow cross section of the square or circular Changeable nozzles.

Crucial for the effect of the Ver driving is that the recirculated flue gas directly in the furnace is blown in. As a result, those in the Resulting high temperatures and the Heat content shifted over a larger flue gas volume.

In the case of a furnace, which uses substoichiometric Air supply below the grate works and thereby gasifying the combustible waste components achieved, the missing stoichiometric proportion of air preheated over the side panels and above the Firing grate fed. The fire mitigation the amount of flue gas used is above the Plate air blown in so that an intense Mixing within the firebox during the Combustion process takes place. The amount of flue gas will fed from the side, the feed being inclined down into the firebox. Through the flue gas recirculation, the temperature profile is ver uniform and thus thermal boiler misalignment far going diminished. At the same time, the oxygen content lowered and the overall thermal efficiency of the Firing improved by the inventive method.

The amount of flue gas fed into the furnace is substituted the combustion air entered via the side wall panels /  Cooling air depending on the calorific value of the waste. The is recirculated flue gas quantity maximum 50 vol .-% of the led sidewall air, corresponding to 10 to 30 vol% of the total flue gas.

Claims (7)

1. Procedure for temperature regulation of furnaces with gradual incineration in waste incineration plants, with 10 to 30 vol .-% of the total smoke gases recirculated and directly into the furnace be blown in half of the garbage bed. 2. The method according to claim 1, characterized in that that the flue gas after flowing through the Boiler and a first cleaning stage recirculated becomes. 3. The method according to any one of claims 1 or 2, characterized characterized in that the flue gas recirculation with a fire optimization regulation is regulated. 4. The method according to claims 1 to 3, characterized records that the flue gases from all sides in the furnace be blown in. 5. The method according to claims 1 to 4, characterized ge indicates that the blowing over the grate length above the side panels and above the grate wide through separate openings in the secondary air beams done. 6. The method according to claims 1 to 5, characterized ge indicates that the opening nozzles of the flue gas guidance in horizontal and vertical inclination ver are changeable. 7. The method according to claims 1 to 6, characterized ge indicates that the free flow cross section square or circular nozzles for the smoke gas supply by changing inserts in the nozzle cross section is changeable.