DE3739132A1 - Process and appliance for thermal treatment of contaminated bulk materials - Google Patents

Abstract

The invention relates to a process for the thermal treatment of contaminated bulk materials (bulk solids), in which the contaminated bulk materials are heated, in a roasting treatment stage, preferably in one or more rotary kilns, in direct heat exchange in countercurrent with hot heating gases, preferably flue gases, and then, as purified bulk material, are available for further use, and in which the gases driven off during heating from the hot bulk material are subjected, together with the heating gases, and after dry dedusting, to afterburning and the exhaust gases (off-gases), after optional final cleaning, are discharged into the environment. It is proposed according to the invention that the separated fine dusts from the dry dedusting process are then heated, in an indirectly heated oven, to at least the treatment temperature of the remaining bulk materials and then, if appropriate, admixed thereto. An appliance for carrying out the process is also described. <IMAGE>

Description

The invention relates to a method for thermal Treatment of contaminated bulk goods, whereby the cont mined bulk goods in an annealing treatment stage, preferably wise in one or more rotary kilns, in direct heat exchange in counterflow with hot heating gases, preferably Flue gases, heated and then as cleaned bulk goods further use and where the Er Gases expelled from the hot bulk material together with the heating gases after a dry dedusting be subjected to combustion and the exhaust gases after a possible Final cleaning to be released outdoors. The invention further relates to a device for performing of such a method with an annealing treatment device, which has one or more rotary kilns, with a dryer dedusting, one on the gas side with dry dedusting bound post-combustion chamber and a device for Ab final cleaning of the exhaust gases until discharge into the open.  

On many former petrochemical sites, mining, especially coke oven plants and their Processing plants and gas plants are in contact mined floors or bulk goods available. Under these contacts mined bulk goods are e.g. B. with tar, phenolic and oily components and heavy hydrocarbons to understand purified masses, in particular excavated contaminated soil, dried mud, clay or can also be silt from harbor basins. For the Reini Mainly organically contaminated soils are thermal The method is excellently suited. Here aromatic, aliphatic and polycyclic / halogenated hydrocarbons completely destroyed. Cyan-contaminated floors can also be cleaned will.

From DE-OS 34 47 079 is a method for thermal loading known contaminated earth, where the contaminated earth through the direct addition of hot combustion gases and Air with partial combustion of the decomposition products like this how the C-fix is thermally treated from the earth and that accruing production gas without prior dedusting for ver Reduction of any toxic components that may occur at high Temperatures is burned. The z. T. considerable dust Part of the production gas can cause problems in the aftermath cause combustion. In DE-OS 32 16 771 the ver combustion chamber designed so that it can also function as a dust cyclone serves. This procedure can also cause problems with the Afterburns come when the dust cakes and ver darning leads. It is also with damage such. B. from the Brick lining of the afterburner to be expected. In addition, the all entrained fine dust on the very high afterburning temperature of well over 1000 ° C. The requires considerable energy expenditure. According to the P 37 16 444 finally provided that in the thermal treatment of the Bulk gases or production gases in front of the Subjecting the afterburning stage to dust removal  the glow dust is separated at ambient temperature mixed with a calcium-containing binder and piecei pelletized against glow dust pellets. These pellets will then together with the untreated contaminated bulk goods ters again in the first annealing treatment stage. The purpose of this treatment of the fine dust is to be that with fine dust extracted at a relatively low temperature the minimum temperature required to clean the contami bring bulk goods. In addition to the elaborate bandage Addition of funds and pelleting must be done with the latter Move the pellets in the first stage from the environment temperature to the required treatment temperature be brought. It also pellets when heated in the annealing treatment stage very mechanically stressed and threaten to disintegrate easily.

The invention has for its object that generic To conduct procedures in a simple procedure the contaminated fines without much energy dusts are cleaned. The invention is also the Task based, one for performing the procedure Specify particularly suitable device.

To achieve this object, the invention provides that the separated fine dust from the dry dedusting closing in an indirectly heated oven, at least on the Treatment temperature of the other bulk goods are heated and then added to them if necessary. Here are the deducted from the task side of the contaminated bulk goods After the dedusting, fine dust is called no intermediate subjected to cooling, but directly for further heating fed to an indirectly heated oven and there on the Be temperature of the other bulk goods heated. In the The particulate matter in particular does not become indirect heating associated with additional smoke gases. It will only the relatively low volume flows of expelled Deducted pollutants that easily with the other heating  or flue gases can be burned. The indirect loading heating is preferably carried out in a vertical shaft furnace, through which the bulk goods continuously from top to bottom be moved. You can in the lower part of the shaft furnace then already subjected to indirect intermediate cooling the. This means that even at high treatment temperatures the temperatures at the discharge devices are relatively low be kept so that not too expensive materials must be used.

The heat of the at usually well over 1000 ° C after the Post-combustion exhaust gases can be direct and / or indirectly for indirect heating of the shaft furnace and then for preheating the combustion media in the Annealing treatment facilities and / or afterburning ge be used. With indirect preheating of the combustion media for indirect heating, those can be generated Flue gases can be disposed of directly in a chimney. object the invention is also an apparatus for performing the described method, that of the initially described Device goes out and is characterized in that to the Dry dust removal on the dust side of an indirectly heated shaft is connected and that the shaft furnace via a För the device for the dust to one of the annealing treatment direction downstream mixer is connected. To the Mixer can clean a cooling device for that bulk goods with a return conveyor for the ge Connect cooled bulk goods to the mixer. Especially at very high treatment temperatures of the bulk goods can With the help of this partial return of the already cooled Bulk goods to the mixer the inlet temperature in the closing cooling drum can be significantly reduced. So that can the cooling drum is also built more simply and cost-effectively the.

The invention is based on the figure, for example explained in more detail.

This single figure shows in a schematic  Representation of a device for performing the described NEN procedure.

The contaminated bulk goods are fed in via ( 1 ) at the top of the first rotary drum furnace ( 3 ). At the opposite end is the direct burner ( 4 ) to which gas (G) and air (L) are fed. In counterflow to the flue gases, the bulk goods are trans ported lengthways through the rotary drum ( 3 ) and dried and heated in direct heat exchange. As a rule, the treatment temperature of the bulk goods is 600 to 800 ° C, whereby the heating takes place in a drum and the subsequent drum can be dispensed with. In this case, the outlet temperature of the flue gases from the rotating drum ( 3 ) near the feed point of the bulk goods is approx. 300 to 350 ° C. However, if the contaminated bulk goods have to be heated to 1200 ° C for certain reasons, two rotary kilns ( 3 ) are connected in series. In this case, the temperature of the flue gases emerging from both rotary drums ( 3 ) in the mixture increases to approx. 500 to 600 ° C. With this direct heating in the rotary kilns, depending on the fineness of the bulk goods, up to 30% by weight, based on the amount of fine dust used, is discharged with the flue gases. This fine dust is in the dry dedusting ( 5 ), the z. B. consists of a bag filter system or multi-cyclones, separated and then brought in an indirectly heated shaft furnace ( 8 ) to the treatment temperature of the other bulk materials. The flue gases enter the post-combustion chamber ( 6 ) where they are treated by the direct burner ( 7 ) at temperatures of 1000 to 1300 ° C. The exhaust gas is conducted via line ( 16 ) to the final cleaning (not shown) and possibly to heat recovery before it reaches the atmosphere via the chimney.

The fine dust separated in the dedusting station with the help of bag filters or multi-cyclones, which due to the circumstances have only been subjected to a treatment temperature of 300 to 350 ° C or 500 to 600 ° C, are heated to a temperature of 600 to 800 in the indirectly heated shaft furnace ° C or, in the alternative, heated up to 1200 ° C with the two rotary kilns. The pollutants extracted here from the fine dust come together with the flue gases from the rotary kilns into the exhaust gas combustion system ( 6 ). The from the indirect heating of the shaft furnace from the Heizwän ( 10 ) accumulating flue gases are sucked off under pressure control via a flue gas blower ( 11 ) and passed via line ( 17 ) to the chimney, not shown. The size of the flue gas pressure in the heating cables is regulated so that it is practically identical to the gas pressure inside the shaft furnace ( 8 ) (± 1 mbar). The lower part of the shaft furnace ( 8 ) is equipped with an indirect cooling device ( 9 ), where the filter dust heated to 600 to 800 ° C or alternatively to 1200 ° C is cooled to below 600 ° C with the help of cooling water ( 15 ) becomes. The cooled filter dust is put together with the thermally treated bulk goods from the rotary drum furnaces ( 3 ) into the mixer ( 12 ) and then also cooled in the cooling drum ( 13 ) with the help of cooling water ( 15 ). At ( 18 ) a bulk material cooled to approx. 50 ° C is then drawn off. In the event that the earth in the rotary drum furnaces ( 3 ) has to be heated to over 600 ° C (e.g. to 1200 ° C), part of the bulk material already cooled to 50 ° C is returned via the return device ( 14 ) Mixer ( 12 ) transported, a mixing temperature when entering the cooling drum ( 13 ) of below 600 ° C is set.

Reference symbol list

(1) Bulk infeed
(2) Annealing treatment facility
(3) rotary drum furnaces
(4), (7) direct burners
(5) Bag filter system or multi-cyclone
(6) post-combustion chamber
(8) indirectly heated shaft furnace
(9) Cooling device
(10) heating walls
(11) Flue gas blower
(12) mixer
(13) Cooling drum
(14) return conveyor
(15) cooling water
(16) Exhaust gas for gas cleaning
(17) Exhaust gas to the fireplace
(18) cleaned bulk goods
L air
G gas

Claims (10)

1. A method for the thermal treatment of contaminated bulk goods, the contaminated bulk goods being heated in a glow treatment stage, preferably in one or more rotary tube furnaces, in direct heat exchange in countercurrent with hot heating gases, preferably flue gases, and then being used for further use as cleaned bulk goods and the gases expelled from the hot bulk material during heating together with the heating gases after a dry dedusting are subjected to afterburning and the exhaust gases are released into the open after a possible final cleaning, since characterized in that the separated fine dust from the dry dedusting finally in an indirectly heated oven, at least heated to the treatment temperature of the other bulk goods and then added to them if necessary. 2. The method according to claim 1, characterized records that the fine dust after the indirect Heating after a, preferably indirect, intermediate  cooling mixed with the other cleaned bulk goods will. 3. The method according to claim 1 or 2, characterized ge indicates that the indirect heating of the Fine dust takes place in the shaft furnace. 4. The method according to any one of claims 1 to 3, characterized characterized in that the indirect Be heating contaminants expelled from the fine dust burned together with the other heating or flue gases will. 5. The method according to any one of claims 1 to 4, characterized characterized in that for indirect heating the exhaust gases from afterburning directly and / or indirectly to be used. 6. The method according to any one of claims 1 to 5, characterized characterized in that the exhaust gases from the indi direct heating to preheat the combustion media the annealing treatment device and / or the afterburning be used. 7. Device for performing the method according to one of claims 1 to 6, with

• an annealing treatment device which has one or more rotary tube furnaces,
• - dry dedusting,
• - a post-combustion chamber connected to the dry dedusting on the gas side and
• - a device for final cleaning of the exhaust gases until discharge into the open,

characterized in that dust-sided an indirectly heated shaft furnace (8) is connected to the dry dedusting (5) and that the shaft furnace (8) is connected via a conveying device for the dust to one of the Glühbehandlungseinrichtung (2) downstream mixer (12). 8. The device according to claim 7, characterized in that the mixer ( 12 ) is followed by a cooling device ( 13 ) for the cleaned bulk goods with a return device ( 14 ) for the cooled bulk goods to the mixer ( 12 ). 9. The device according to claim 7, characterized in that the shaft furnace ( 8 ) is provided in the lower part with a cooling device ( 9 ) for indirect cooling of the fine dust.