DE3827086A1 - Process and apparatus for thermal decontamination of filter dusts and other residues - Google Patents

Abstract

The process and apparatus according to the invention provide a decontamination of dioxin- and furan-containing dusts, which simultaneously also contain heavy metal compounds, by subjecting them to thermal decontamination in an inductively heated crucible furnace. The material to be decontaminated is put into the liquid state at temperatures between 1400 and 1600@C and appropriate residence time, toxic portions, such as dioxins and furans, being completely destroyed and heavy metals being bound so that they cannot be leached out. The material is tapped after a melting process and is cooled in a quenching vessel. Grinding is not necessary. Gaseous portions from the crucible furnace are passed through a high-temperature section, then quenched and particulate constituents are separated off in a high-performance deduster. The crucible furnace can be operated either batchwise or continuously; in the continuous mode, the outlet orifices are dimensioned in such a way that, from a defined temperature, the melt drains off by itself and throughput can be controlled via the furnace heating.

Description

The invention relates to a method and a front direction for decontamination of toxic dusts such as Filter dust from incineration plants, pyrolysis plants, paint sludge treatment plants and other residues industrial processes where toxic components are in the form of polychlorinated or polybrominated dibenzodioxins and Dibenzofurans can be included and also heavy contain metals or heavy metal compounds.

Efforts to solve the problem to date have been based either on an integration of the filter ash in concrete or cementitious materials, in the leaching or in the thermal treatment.

So far, there are two ways, especially in thermal treatment known. On the one hand, it is suggested by the heat action in the temperature range up to 400 ° C under reducing Conditions the dioxins and furans with approx. 95% efficiency to destroy; a landfill ability of the resulting product remains severely restricted, however, since the heavy metals almost remain unchanged in the dusts and dioxins and Furans are ultimately detectable.  

Another suggestion is based on the filter dust in a plasma furnace, where it is placed above the Melting pool arranged three-phase plasma torch very quickly be heated. The temperatures here are <2000 ° C ensure complete destruction of the dioxins and Furans and the transfer of a large part of the heavy metals in the gas phase. Due to the influence of gravity Filter dust in the melt pool, the temperature in the range of 1200 to 1600 ° C, a.

A disadvantage of this method, however, is that a specific one Not the surface due to the high thermal energy of the melt pool, but directly with the gas phase in the subsequent condensation and flue gas cleaning. In addition, the construction and operation of an arc furnace associated with considerable expenditure, so that the specific Treatment costs of this procedure are considered high.

The object of the invention is now to correspond to a of the method using an apparatus to create the the goal set, namely the elimination of the filtera existing dioxins and furans and the integration of Heavy metal connections made easy. In particular The goal is to achieve the process as a process step into a thermal waste treatment nen.

This object is achieved according to the invention in that the material to be decontaminated is either conveyed directly after discharge from the filtering dust extractor or electrostatic precipitator into an intermediate container or is collected from several locations in a central buffer store ( 1 ). The material for thermal decontamination is released from this dust collector via a transport system ( 2 ). If necessary, a so-called accelerator can be added at this point, which is stored in a separate silo ( 3 ). The purpose of this accelerator is to accelerate the melting of the material to be decontaminated and to achieve a corresponding structure of the end product.

The material enters the actual crucible furnace ( 4 ) via the closed feed device and is melted there either in batches or in a continuous process.

In any case, the process step is characterized by inductive heating of the crucible furnace, with which the destruction of dioxins and furans and the binding of heavy metal compounds can be carried out in a simple manner. According to the task, the crucible furnace can be operated in a reducing manner by nitrogen flushing or in an oxidizing manner by adding oxygen. The crucible furnace is heated, for example, via a mains transformer ( 5 ), a rectifier set ( 6 ), inverter set ( 7 ) and the actual resonant circuit, consisting of an induction coil and compensation capacitors ( 8 ).

After completion of the melting process and the corresponding dwell time, the crucible furnace is tapped via a tapping channel ( 9 ) into a cooling container ( 10 ), where quenching takes place in a water bath. The cooled material is discharged into the transport container ( 11 ) by means of a scratch.

The material treated in this way is an aggregate usable or can be brought to normal landfills. Because of the significantly reduced volume also results in savings landfill volume and costs.

The gas withdrawn from the crucible furnaces is passed over a high-temperature section ( 12 ) to ensure burnout and then spontaneously cooled to approx. 200 ° C. This takes place in an evaporative cooler known from flue gas cooling with subsequent separation of the solids in a high-performance deduster ( 13 ). The residual product ( 14 ) discharged here is returned to the crucible furnaces or the storage container ( 1 ).

The excess exhaust gas volume can be according to the local Possibilities either to the waste gas stream of waste incineration out or through a separate flue gas scrubber (for Ab separation of any chlorine and sulfur components) the atmosphere can be derived.

It makes sense to use a pendulum system driven so that a crucible is always in operation during the others are recharged.  

Another suggestion is to run the induction-heated crucible furnace as a continuous system according to Fig. 2; This is achieved in that the crucible furnace is equipped with tapping facilities on the floor. These are preferably located near the wall, the tapping lines leading to the quenching bath in this case as well.

The drain openings are preferably dimensioned such that when a certain furnace temperature is reached, the melt can drain off independently. Therefore, the Re throughput is achieved by heating the crucible furnace respectively.

Claims (10)

1. Process and device for thermal decontamination of filter dusts and other residues, in particular residues from incineration plants, pyrolysis plants, paint sludge preparation plants, characterized in that the material for removing any dioxins and furans contained and for preventing possible leaching contains heavy metals in one an inductively heated crucible furnace is brought in, there is melted at temperatures of 1400 to 1600 ° C, the liquid phase is discharged and quenched in a water bath, at the same time the gas phase forming is driven over a high temperature path of at least 1200 ° C, then the exhaust gas is suddenly cooled down by an injection cooler and solids are separated in a downstream high-performance deduster, which in turn can be fed into the crucible furnace. 2. The method according to claim 1, characterized in that the Crucible furnace exhaust gas generated over a high temperature route in which at high temperatures (at least 1200 ° C) and dwell times of over 2 seconds Inertization or decontamination of the exhaust gas takes place. 3. The method according to claim 1 or 2, characterized in that after the thermal afterburning a shockarti cooling of the exhaust gas in an injection cooler to approx. 200 ° C he follows. 4. The apparatus of the method according to claim 1, 2 or 3, characterized characterized that the crucible furnace either with parallel resonant circuit converter or with series resonant circuit converter is equipped. 5. Apparatus according to claim 1, 2, 3 or 4, characterized in that the crucible furnace is used in batch operation, where two furnaces can be operated in a pendulum to increase the throughput. ( Fig. 1) 6. Apparatus according to claim 1, 2, 3 or 4, characterized in that the crucible furnace is equipped as a continuous system with drain openings on the floor, which are preferably arranged in the edge area. ( Fig. 2, No. 15) 7. Device according to one of claims 1-6, characterized records that the reactor was inert by adding nitrogen can be ren. 8. The method according to any one of claims 1-7, characterized net that iron shavings in the material to be decontaminated as Accelerators can be abandoned. 9. The method according to any one of claims 1-8, characterized net that the so-called accelerator is not made of iron, but made of other metallic conductive, powdery materials consists. 10. The method according to any one of claims 1 to 4 and 5, characterized characterized in that the drain openings are dimensioned so that the withdrawal of the liquid melt from a certain tem temperature, for example 1400 ° C, takes place automatically and the Flow control simply by heating the tie done.