DE2601932C3 - Process for separating the dusty and aerosol or gaseous pollutants that occur in a drum dryer - Google Patents

Description

The invention relates to a method for excretion that in a drum dryer during the processing of a granular solids and bituminous Mixtures containing binders to form a bituminous mix resulting from the solids Accruing dusty and aerosol or gaseous pollutants arising from the binding agent.

With the German file? *. 1594815 was i.a. a method is known in which the light-dried solids are mixed with the liquefied binder and then mixed with strong heating.

When producing the bituminous mix according to the instructions in this publication, the Fine particles adhering to coarser grains are initially fixed on them by the water film, whereby the task of binding the fine particles through the water as the process progresses, i.e. during evaporation of the water, through the binder, which causes spreading in this temperature range is taken over. The binder droplets lying against the grains are in this process converted into the thinnest films enveloping the individual particles.

The originally expected, practically zero reduction in emissions and thus the possible waiver of dedusting systems was at least not achieved in every case. In the Emissions measured in practice show only 0.03 to 0.1 times the value of normal emissions of a drum dryer, i.e. values that were used at the time of the initial registration of this process Definitely justified the term "dustless", but vice versa - in view of the growing demands of environmental protection - no longer meet today.

Deposition processes are state-of-the-art and combinations of tumble dryers and separators or dust extractors that form structural units known.

For example, a drying drum is described by the German patent specification 499920 * in the case of the im Aus

case the drum one with the drum itself

rotating, annular filter disc is arranged, this filter disc is made of prösem stone.

Furthermore, the German patent

■ i script 559 136 the combination of a drying drum with a damming and dedusting device is known, the criterion of which is a wind stop consisting of several interlocking funnels with partially perforated baffles, where d ^; esem

In the passage a storage ring is connected upstream. A newer, identified by DE-AS 2362725 method provides that a subset of the Granular material to be dried that is still moist forms a vertical trickle layer through which the exhaust gases the drum.

However, none of these methods and devices can meet the requirements arising from the fact of a more or less strong elimination of especially low-boiling hydrocarbons result from the bituminous binder in the drum.

In particular, with these facilities the The risk of the system being silted up cannot be countered. Apart from these difficulties it will the assignment of a per se known dedusting system with a high degree of separation to a treatment process does not do justice to the above-mentioned new processing method, because of the high expenditure of these dedusting systems, which are the result of the new

jo preparation process given advantages are essential would reduce.

It is therefore the object of this invention to provide a method for excretion or precipitation that is more solid and gas, vapor or aerosol emissions

to propose j5 nen from a drum dryer, wherein in this dryer a mixture of disperse solids and a bituminous binder to one bituminous hot mix is prepared during its passage.

The Filteimittei to be used against the possible mechanical, thermal and chemical influences sufficiently resistant and light be cleanable. Furthermore, the range of the optimum volume resistance of the exhaust gases must be to be adjusted and controlled by the filter materials, as compliance with this is essential for the efficiency of the Separator system is decisive. When performing the aforementioned preparation process for production a bituminous hot mix are im

r _{) 0} general emissions of 0.08 to 0.6 g / m ^{1 are determined, while 4 to 12 g / m 1 are} measured when the classic methods are used.

Expressed in a very general way, these are the advantages already given with the least possible effort to expand further. Of course, no linearity of the result can be expected from these efforts will; reducing emissions that are already approaching zero is and remains more expensive than theirs Dismantling from above.

In connection with the classification given at the beginning It is therefore proposed that the gases carrying the pollutants be replaced by an in and of itself known bulk material or fiber filling containing layer filter and the pollutants in the filter

layer are excreted, and that the filter layer in definable time intervals from the accumulating Fabrics are cleaned by shaking and / or wet rinsing j until a vöreiristell-

lower lower volume resistance sets.

The progress resulting from this solution to the stated problem is

1. the possibility of using filter material that is neither against overheating nor against possible Falling below the dew point is sensitive and easy to clean.

In this case, coking coal, activated carbon, metal oxides or the like can be sorbing or reducing substances are at least partially introduced into the filter material;

2. the possibility of spraying water on the filter layer from the clean gas side to bring about the condensation of the pollutant gases or to support one possibly at the same time effective mechanical filter cleaning;

3. the possibility of returning the separated material to the mixed material and its risk-free Integration into the mix flow;

4. the possibility of practicing the procedure in the area of the optimal degree of filter effectiveness Setting or taking into account time intervals for cleaning the filter plugs and ending these intervals when one is reached presettable lower volume resistance.

The method is illustrated schematically by way of example using the drawings.

Fig. 1 shows the design of the suction head of a drum dryer;

Fig. 2 shows the suction head provided with sheet filter elements;

FIG. 3 repeats the illustration according to FIG. 2, but the separation area is additionally provided with a Nozzle ramp equipped;

4 shows a partial section through a sheet filter with a coke filling;

Fig. 5 shows a section through a single filter element. From this illustration, sine is preferable The construction of the filter can be seen.

The solid arrows indicate the path ϊ of the solids. The open arrows indicate the Way of the exhaust.

The end of the drum dryer tube 1 opens into the suction head 2, which upwards into the separation area 3, which is variable in its equipment, is transferred to the one with the outlet on the clean gas side 13 is equipped.

Through the wall 12, the suction head 2 is in an outlet area with an outlet 14 and in a Shared dust collection room. The separated material is fed into the discharge area by a screw 4 promoted.

Apart from baffles 6, the partition 12 must also have a deflecting and pre-separating Effect will be awarded.

2u In the separation area 3 are the support profiles 5 for the bedding of the sheet filter earth. fite 7 pulled in. The Schichlfiiterelemenlc 7 build from one lower filter base 8, an upper filter base 9, a frame 10 on which the lower filter base 8 rests, as well as a 0.1 m thick layer of coke 11.

The outlet cross-sections from the upper filter base 9 are opposite to the inlet cross-sections in the lower filter base 8 is reduced. About the spray

jo ramp 15 the liquid is dispersed and the The surface of the filter elements is practically completely exposed.

The performance of a filter element with a layer thickness of 0.1 mm and an impact area

j5 of 1 x 1.5 m and a weight of about 140 kg corresponds to the amount of exhaust gas when burning approx. 150 kg / h heating oil.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Process for separating the in a drum dryer during the processing of a granular solids and bituminous binders containing a mixture to a bituminous Mix produced in powder form from the solids and from the binding agent accumulating aerosol or gaseous pollutants, characterized in that the Gases carrying pollutants through a bulk or fiber filling known per se The sheet filter (7) is guided and the pollutants are separated out in the filter sheet (10), and that the filter layer (10) from the accumulating substances at definable time intervals is cleaned by shaking and / or wet rinsing until a presettable sets lower volume resistance.