DE4435166C1 - Assembly to vitrify contaminated waste - Google Patents

Abstract

To vitrify waste matter, such as sewage sludge or contaminated sludge or soil or slag and filter dust such as from rubbish incinerators, an assembly to dry and degas and oxidise and sinter the material is between the station to mix and dose the waste and vitrifying agent, and the glass smelting station (15). The regenerators (17), to heat the combustion air for the smelting station (15), are against the flow of the fed combustion air, heated by the exhaust gas from the smelting station (15). The exhaust gas temp., on passing through the regenerators (17), is held at a level to prevent the development of condensation. A recuperator (19) follows the regenerators (17), with exhaust gas flowing through, for condensation to be separated from the steam phase and fed to the preparation station. The recuperator (19) heats the combustion air for the assembly to dry, degas, oxidise and sinter the dosed material.

Description

The invention relates to a method for glazing Residues such as sewage sludge, contaminated sludge or soils, slags, filter dusts, in particular Waste incineration plants, the residues in one Processing plant to be processed in one Batch plant the processed residues and glass formers can be mixed and dosed in one with firing operated glass melting plant melted the batch is that with a facility for regenerative Heat recovery from the flue gases from the furnace is coupled, the flue gases via a Cleaning system are handed over.

A system for glazing residues is in the booklet to the magazine "Rubbish and Waste" No. 31, 1994, disposal of slags and other residues, page 167 to 172, described, where there is a regenerative operation not possible.  

A method and device for thermal Treatment of waste materials, in particular for regenerative heat recovery from the flue gases of a Firing is known from EP 0 362 553 B1.

Such systems are used to manufacture remineralized products from residues, such as Example municipal or industrial sewage sludge, contaminated sludges from rivers, lakes and Harbor basin, slags and filter dusts Waste incineration plants and contaminated soils from industrial or military locations and the like. The residues are in such plants melted down and then leach resistant Processed recyclables.

The final ones to be removed from the glass melting plant Material flows are divided into three components.

A first component is used to manufacture Molded components from the first heat.  

Depending on the cooling behavior, a dominantly glassy one or a dominant crystalline matrix can be produced. Such molded components are among others for the following Areas of use: abrasion protection, sewage systems, Dike structures, molded glass, cable routing, acid construction.

A second component can be used to manufacture Melt granules are used, which for example can be used in road construction.

A third component is that in the glass melting plant due to their high specific weight in the Metallic "Soil sow" that separates the floor area is editable or processable.

Another component ultimately arises from Separation and processing of heavy metals and Alkaline from the vapor phase, but in the process cycle remains or is processed.

In order to be able to work economically with such systems, it is necessary that from the glass melting plant exhaust gases for regenerative preheating of the Use combustion air.  

Such a regenerative is in EP 0 362 553 Heat recovery and use for the combustion air preheating known per se.

The disadvantage here is that the condensation of constituents in the exhaust gas are such Add regenerators over time and the corresponding components must be replaced, which are added with appropriate condensates. The The condensate must be again in a complex manner be returned to the process so that the corresponding components do not occur as hazardous waste.

DE 42 26 642 A1 is a regenerative glass melting furnace and a method of operating this glass known furnace. There is a system there Regenerators and recuperators previously known, but serve there the recuperators only for air preheating. In the Regenerators already form a condensate and Deposition. This results in the disadvantages that already are described above.

The invention is based on this prior art the task underlying a method of the generic type  to create, in spite of being regenerative Heat recovery from the flue gases for preheating the combustion air of the glass melting system of additional residues to be disposed of avoided becomes.

To achieve this object, the invention proposes that between the batch plant for mixing and dosing the residues and glass formers and the glass melting plant a device for drying, degassing, oxidation and sintering of the metered batch is switched on, that the regenerators for heating the combustion air for the glass melting system in counterflow to the feed Combustion air from the waste gas from the glass melting system are flowed through, the exhaust gas temperature at Throughput of the regenerators at such a level is kept that condensation is avoided and that the regenerators are followed by a recuperator which is traversed by the exhaust gas and in which Condensates separated from the vapor phase and the Processing plant are fed, being in the recuperator the combustion air for the drying device, Degassing, oxidation and sintering of the metered batch is preheated.  

It is preferably provided that as a device for Drying, degassing, oxidation and sintering of the metered batch, a rotary hearth furnace is used, which is heated with fossil and / or other fuels and into which preheated combustion air is introduced.

For optimal use of the exhaust gas energy from the Glass melting plant becomes a combination of regenerators and recuperator used. In the regenerators the combustion air for the glass melting system is heated. After leaving the regenerators, the exhaust gas is in one Recuperator directed. The condensates are in the recuperator separated from the vapor phase and the combustion air heated for the rotary hearth furnace. To the formation of condensate in the regenerators to avoid it is necessary especially through structural measures, the colder ones Not to let areas drop below a temperature, in which condensation occurs.

A preferred further development is seen in the fact that the exhaust gases from the rotary hearth furnace or the like of a fossil heated exhaust gas post-combustion stage, connected on the input side to the glass melting furnace becomes.  

It is also preferably provided that the exhaust gas temperature the regenerator stage is kept at at least 850 ° C.

It is also preferred that the entire system under atmospheric normal pressure or low negative pressure, due to the use of suction trains. Another preferred further development is seen in that an SM furnace is used as the glass melting furnace.

The rotary hearth furnace according to the invention can run on fuels inferior quality, such as waste oils, petroleum coke or coal sludges are operated autothermally. Of the Use of high quality energy sources or pure Oxygen is not required.

The operating temperatures of the individual system parts are approximately as follows:
The rotary hearth furnace is operated at temperatures between room temperature and 1300 ° C.

The glass melting furnace is between 1300 ° C and 1700 ° C operated.  

The regenerators are between 1700 ° C and 850 ° C operated.

The recuperator is operated between 1200 ° C and 200 ° C.

A method is available with the invention provided that for the complete conversion of residues in environmentally friendly materials. With the procedure no additional residues are generated, which in turn Landfills would have to be fed. The legal Specifications regarding exhaust gas purity and the like are adhered to.

The delivery of residues using the process can be processed by ship or by train take place, with intermediate storage in bunkers or Silos is possible. In a first step the input material is processed. This includes the Classification, the deposition of metallic components, crushing, pelletizing and drying. In one The second step is the processed input materials analyzed.  

According to the results of the analytical examination Appropriate menus are created that show the exact offset to produce the desired type of glass. in the third step are the offsets of a thermal Pretreated in the rotary hearth furnace. Instead of a rotary hearth furnace can also be a rotary kiln Shaft furnace, a fluidized bed furnace or a deck furnace be used.

The pretreatment in the rotary hearth furnace is, however prefers. This involves drying and degassing up to about 400 ° C, followed by an oxidation up to approx. 800 ° C and then sintering up to approx. 1200 ° C. The hot offset then becomes immediate via appropriate discharge devices in the glass melting plant (preferably an SM oven or a glass tub) and depending on the composition between 1400 ° C and 1600 ° C melted down. In the course of the melting process all toxic organic compounds completely destroyed and the remaining heavy metal oxides are in the Glass matrix integrated.  

The metallic "bottom sow" that forms under the glass bath is tapped from time to time and for Further processing provided. Depending on the size of the furnace and power will melt the glass after a dwell tapped from several hours and according to the final product lines processed.

The exhaust gas from the melting unit becomes preheating the combustion air passed through the regenerators. From there it reaches a recuperator, in which Heavy metal and alkali vapors are separated and the air is preheated for the rotary hearth furnace. Then will it fed a multi-stage exhaust gas purification and there cleaned according to legal regulations.

The exhaust gas residence time prescribed by law in the rotary hearth furnace of 2 seconds Extending the exhaust duct accomplished, the Exhaust duct is designed so that dusts at the same time can be separated and fed to the weld pool.

The procedure according to the invention is energetic  extremely advantageous, since no pure oxygen is required becomes. The rotary hearth furnace can reduce fuel consumption Quality can be operated autothermally. Because of the very good Exploitation of the exhaust gas energy in connection with the Regenerators and recuperators become energy consumption minimized. The use of SM furnaces as a glass melting plant is particularly preferred because it enables is that, for example, existing, decommissioned industrial locations of SM ovens or of Glass tubs can be reactivated with low investment and with an accelerated Approval procedure, since the locations themselves are be stuck.

Below is a flow chart of the Process flow clarified and a plant concept shown.

It shows:

FIG. 1 shows a concept of a meltdown and Remineralisierungsanlage;

Fig. 2 is a flow diagram for a smelting plant in view.

The concept of a melting and remineralization plant is shown in FIG . The raw materials (MVA slags and filter dusts, sewage sludge, contaminated soils and sludge, SMVA slags and the like) are fed to a treatment. The raw materials are classified in the preparation. There is a metal deposition. Furthermore, the raw materials are crushed, mixed, pelletized and dried there. The deposited metals (Fe and non-ferrous metals) are deposited and sent for analysis. The processed substances are fed to a dosage and fed to a rotary oven in menus, which is fed with heating medium and in which drying and degassing as well as oxidation and sintering of the quantities entered takes place. The batch pretreated in this way is introduced into a glass melting furnace, exhaust gas afterburning of the exhaust gases from the rotary hearth furnace taking place and introduction of heating medium into the glass melting furnace. In addition, additional heating medium is introduced into the glass melting furnace. The melt is drawn off from the glass melting furnace and final products are derived therefrom. The metal produced in the glass melting furnace is cut off, analyzed and used. The glass melt of the glass melting furnace is also analyzed. Furthermore, regenerators are provided for heating combustion air for the glass melting furnace, the exhaust gas being conducted from the glass melting furnace in counterflow to the combustion air supplied. The exhaust gas temperature is kept at such a level during the throughput of the generators that condensate formation is avoided. The regenerators are followed by a recuperator through which the exhaust gas flows and in which the condensates are separated from the vapor phase. These condensates are analyzed and processed. The combustion air for the rotary hearth furnace is also preheated in the recuperator. After the recuperator there is a multi-stage exhaust gas cleaning according to 17.BlmSchV. The exhaust gases are then released through the chimney.

The exhaust gas purification products are analyzed and processed. In Fig. 2 is a flow diagram for a Einschmelzanlage in view is shown. 1 denotes a binder silo. At 2 , a raw material bunker is specified, from which the raw materials are drawn off via a scraper chain conveyor 3 . These raw materials are then fed to an Fe metal separator 4 and a non-ferrous metal separator 5 . The raw materials are then sieved in a sieve 6 , with a mesh size of 0.5 to 5 mm. Larger constituents are broken in a tuber breaker 7 and fed to the sieve 6 again. From this sieve 6 , a dosing container 8 is fed with pelletizing plate 9 . In addition, aggregates 10 are added and these components are introduced into a feed hopper 11 . Downstream of the feed hopper 11 is a rotary hearth furnace 12 with burner 13 and afterburner chamber 14 . Downstream of the afterburner is a glass melting furnace 15 with final product take-off 16 . From the glass melting furnace 15 , the exhaust gas is passed through regenerators 17 , through which combustion air flows in counterflow. The gas flow can be switched from exhaust gas to hot air through the elements 18 .

A recuperator is indicated at 19, which is connected downstream of the regenerators 17 . Combustion air is introduced into recuperator 19 at 20 . The fuel supply to the rotary hearth furnace 12 and burner 13 and to the regenerators 17 is indicated at 21 . Further system components are shown on the right in FIG. 2. It is a first heat exchanger 22 , a second heat exchanger 23 , a spray absorber 24 , a bag filter 25 , a two-stage washer 26 , a lime milk tank 27 , a neutralization tank 28 , a supply of process water 29 , an adsorbent silo 30 , a dry sorption , Contact section 31 , a second bag filter 32 , a further heat exchanger 33 , an ammonia injection 34 , a catalyst 35 , a chimney 36 and a suction 37th With suction, the entire system is operated primarily under low vacuum. The specified elements are used for exhaust gas purification and are only given for explanatory purposes.

Reference list

1 binder silo
2 raw material bunkers
3 scraper chain conveyors
4 Fe metal separators
5 non-ferrous metal separators
6 sieves <0.5 mm to <5mm
7 bulb breakers
8 dosing containers
9 pelletizing plates
10 aggregates
11 feed bunkers
12 rotary hearth furnace
13 burners
14 afterburner
15 glass melting furnace
16 Final product deduction
17 regenerators
18 Exhaust / hot air change
19 recuperator
20 combustion air
21 fuel
22 heat exchanger 1
23 heat exchanger 2
24 spray absorbers
25 bag filter 1
26 2-stage washer
27 milk milk containers
28 neutralization containers
29 process water
30 adsorbent silo
31 dry sorption, contact path
32 bag filter 2
33 heat exchanger 3
34 Ammonia injection
35 catalyst
36 chimney
37 induced draft.

Claims (6)

1. Process for the glazing of residues, such as sewage sludge, contaminated sludge or soil, slags, filter dusts, in particular from waste incineration plants, the residues being processed in a processing plant, the processed residues and glass formers being mixed and metered in a batch plant, in a furnace operated glass melting system, the batch is melted, which is coupled with a device for regenerative heat recovery from the flue gases of the furnace, the flue gases being emitted via a cleaning system, characterized in that between the batch system for mixing and metering the residues and glass formers and the glass melting system ( 15 ) a device for drying, degassing, oxidation and sintering of the metered batch is turned on, that the regenerators ( 17 ) for heating the combustion air for the glass melting system ( 15 ) in counterflow to the supplied combustion ngsluft through the exhaust gas of the glass melting system ( 15 ), the exhaust gas temperature during the throughput of the regenerators ( 17 ) is kept at such a level that condensate formation is avoided and that the regenerators ( 17 ) are followed by a recuperator ( 19 ) which is flowed through by the exhaust gas and in which its condensates are separated from the vapor phase and fed to the treatment plant, the combustion air for the device for drying, degassing, oxidation and sintering of the metered batch being preheated in the recuperator ( 19 ). 2. The method according to claim 1, characterized in that a rotary hearth furnace ( 12 ) is used as a device for drying, degassing, oxidation and sintering of the metered batch, which is heated with fossil fuels and introduced into the preheated combustion air. 3. The method according to claim 1 or 2, characterized in that the exhaust gases of the device for drying, degassing, oxidation and sintering of the metered batch are fed to a fossil-heated exhaust gas post-combustion stage ( 14 ) which is connected on the input side to the glass melting furnace ( 15 ). 4. The method according to any one of claims 1 to 3, characterized in that the exhaust gas temperature of the regenerator stage ( 17 ) is kept at at least 850 ° C. 5. The method according to any one of claims 1 to 4, characterized in that the entire system is operated under atmospheric normal pressure or low negative pressure, due to the use of suction trains ( 37 ). 6. The method according to any one of claims 1 to 5, characterized in that an SM furnace is used as the glass melting furnace ( 15 ).