DE102020113329A1 - Process and device for splitting strongly adsorbing substances to suppress the adsorption effect in regenerative exhaust air purification systems - Google Patents

Abstract

Process for splitting strongly adsorbing substances for odor elimination and for suppressing the adsorption effect in regenerative exhaust air purification systems by splitting off functional groups and / or partial oxidation into non-adsorbing or less adsorbing substances as well as non-or slightly odor-prone substances characterized in that an exhaust gas containing these substances at a Temperature of 200 ° C to 450 ° C is brought into intensive contact with a substance or a mixture of substances with a large internal and / or external surface.

Description

The invention relates to a method and a device for splitting strongly adsorbing substances to suppress the adsorption effect in regenerative exhaust air purification systems according to the preamble of claims 1 and 6.

State of the art

Exhaust gas or exhaust air cleaning is understood to mean the removal of harmful components from the gas phase. The terms exhaust gas and exhaust air are used inconsistently.

Exhaust gas cleaning is the process of removing air pollutants from exhaust gases. To remove solid and liquid components in the exhaust gas, the processes of dedusting, aerosol separation and flue gas cleaning are used. For gaseous, but also solid, liquid or drop-shaped substances, depending on the chemical and physical properties of the substances, processes of absorption, adsorption, catalytic cleaning, thermal cleaning, post-combustion, etc. can essentially be used. The person skilled in the art knows the details of these methods as well as the fact that these methods partly interlock and partly are also used in combination with one another. Some aspects of this are therefore briefly presented below as they are or may be of interest in relation to the background of the invention.

Adsorption processes are used both for cleaning industrial exhaust gases and in building services, for example in extractor hoods. Air pollutants, in particular hydrocarbons, are removed from the exhaust gas to be cleaned by attaching them to the inner surface of porous adsorbents. Fixed bed, moving bed, rotor, fluidized bed and entrained flow adsorbers, for example, can be used for this purpose. For example, it is known to extract volatile organic hydrocarbon compounds (volatile organic compounds (VOC)) from a low-concentration exhaust air stream and to feed the adsorbed solvents in a highly concentrated subsequent exhaust air stream for further treatment

Chemical exhaust air purification systems, for example, use absorption scrubbers to separate different constituents of the exhaust air. Depending on the Henry constant, temperature, pressure and transport acceleration through further chemical reactions in the liquid phase, efficiencies of 95 to> 99% can be achieved and therefore scrubbers are used to separate HCl, NH ₃ , HF, NOx, formaldehyde, H ₂ S, SO ₂ , SF ₆ , mercaptans, amines, ketones, alcohols are suitable. Non-aqueous washing media with low vapor pressure are also known, such as biodiesel, anthracene, amines, Genosorb® or ionic liquids, which are more suitable for certain compounds and conditions.

Thermal exhaust air purification systems are often used when processes for biological and chemical exhaust air purification cannot be operated efficiently. The thermal processes include recuperative thermal oxidation, regenerative thermal oxidation and catalytic oxidation.

Special aspects must be taken into account when cleaning odors. Instead of exhaust gas purification, one should speak of exhaust air purification.

Odor emissions regularly lead to considerable nuisance in the neighborhood. The elimination or reduction is required by law in many countries and is the subject of numerous bilateral and multilateral agreements.

Odors often result from a mixture of up to several hundred individual substances. Odors are therefore also referred to as the cumulative effect of a large number of odorous individual substances.

Several hundred individual substances and gases of various concentrations and properties can contribute to an odor and contain water-soluble / non-water-soluble substances, organic or inorganic substances, etc.

To reduce odor emissions, scrubbers, bio-scrubbers, bio-filters, adsorbers, chemical scrubbers, or thermal systems are used, but they are all subject to fundamental problems because they cannot generally capture the aforementioned cumulative effect and thus eliminate it again.

This cumulative effect is the result of the odor intensity, i.e. the strength of the olfactory sensation triggered by an odor stimulus. The odor intensity generally increases as the concentration of the odorous substance increases. Odors are absorbed by the human nose, which, together with the other sensory organs, contributes to the perception of whether such odor emissions are to be regarded as significant and thus as harmful environmental effects. Furthermore, ie in addition to the odor intensity, the cumulative effect is related to the hedonic (it smells pleasant, unpleasant, neutral) and the daily and seasonal distribution of the effects. The potential of an odor thus becomes largely determined by three measured variables, namely the odor concentration, odor intensity and the hedonic odor effect.

It is this complexity that the exhaust air purification technologies known in the state of the art often fail because of the significant reduction or even elimination of odor emissions in their multitude of manifestations, so that the state of the art is regularly only very rarely able to cope with the known process engineering To propose a generally applicable exhaust air purification system based on calculation models.

Based on these disadvantages of the prior art, it is therefore the object of the present invention to provide a method and a device for exhaust air purification of odor emissions that can be used universally, is inexpensive and requires little temperature.

These aspects are achieved with a method according to claim 1 and with a device according to claim 6. Preferred embodiments are disclosed in the subclaims.

Brief description:

The invention relates to a method and a device for splitting strongly adsorbing substances for the suppression of the adsorption effect in regenerative exhaust air purification systems, which comes about that, according to the regenerative principle, the heat exchanger medium alternately comes into contact with unpurified and purified exhaust gas, the temperature of the cleaned exhaust gas due to the thermal efficiency of usually 95 - 97% is around 23 to 40 ° C higher than that of the unpurified exhaust gas and thus strongly adsorbing substances in the first process step of the regenerative heat exchange on the same, especially at its cold end and so that the exhaust gas inlet side adsorb and in the second process step, are desorbed with the warmer purified exhaust gas from there and get into the chimney or the environment uncleaned.

According to the invention, a substance or a mixture of substances with a large inner surface is used, this can be done, for example, in the form of a bed or as a washcoat applied to a ceramic honeycomb carrier, and brought into intensive contact with the exhaust gas at a temperature of preferably 200 to 450 ° C , whereby the strongly adsorbing substances, be it because of their polarity, their molecular weight, their low volatility or their ability to form hydrogen bonds, are converted into non-adsorbing substances or significantly less adsorbing substances by splitting off functional groups and / or partial oxidation.

According to the invention, the required temperature is either already provided by the exhaust gas temperature or achieved according to the device described here with the help of a regenerative or recuperative heat exchanger, the energy input required for this originating completely or partially from the cleavage and partial oxidation reaction and, if necessary, the remainder from external energy, independently in what shape.

Any organic substances deposited in the heat exchanger over time can be completely oxidized from time to time by means of bake out or pyrolysis by raising the temperature to 400 - 450 ° C.

Detailed description:

• Zu den die Geruchsemissionen auslösenden Einzelstoffen gehören in großem Umfang sog. hoch-siedende Verbindungen. Diese sind ein Problem für die Reinigungsleistung zum Beispiel einer RTO-Anlage (regenerative thermische Oxidation), weil sie von dieser nicht in ausreichender Weise reduziert werden können.

The basics of the invention include the following findings and relationships:

• The individual substances that trigger odor emissions include, to a large extent, so-called high-boiling compounds. These are a problem for the cleaning performance of an RTO (regenerative thermal oxidation) system, for example, because it cannot sufficiently reduce them.

Experiments by the applicant with such an RTO system have shown that precisely when the concentrations of the odorous substances are low and high-boiling compounds are involved, it is possible that instead of the expected 99.8% cleaning performance, which the applicant achieves for her non-adsorbent substances with the three-bed system used by her, only achieves 30% to a maximum of 40% for such odorous substances in the elimination of odor emissions. Even a value of 40% is little if you compare it with the 99.8% exhaust gas cleaning achieved for the usual substances to be cleaned. In this case, it is no longer justified to use an exhaust air purification solution, which is expensive to invest, to reduce odorous substances, even if the RTO system is the most robust form and is also one of the most efficient and economical systems for exhaust gas purification.

This also includes the fact that odorous substances, such as those found in the flavoring industry or in perfume production, etc., but which also include other unpleasant smells such as in the case of animal carcass processing or slaughterhouses, are mostly very strongly adsorbent substances, which already in very low concentrations, which therefore have a very low odor threshold, are effective and can therefore have a disruptive effect even at very low concentrations.

The present invention also takes into account that odorous substances rarely contain hydrocarbons in such a high concentration that their combustion already produces a relevant heating output. This means that the intended cleaning of odorous substances would have to heat up in order to reach the required combustion temperature. This increases the energy requirement considerably if one thinks of the temperature ranges of approx. 600 ° to approx. 900 ° C. and more that are customary in such cleaning processes.

The applicant has therefore designed the method and the device in such a way that additional heating can be limited to low values, that is to say the method can be carried out at the lowest possible temperature. Furthermore, the process can be used to lower high boiling points or a high tendency to adsorb the chemical compounds in question.

It is therefore not absolutely necessary for the chemical compound in question to be completely oxidized during the cleaning process, but rather the cleaning process is designed in such a way that the odor can be eliminated or at least significantly reduced.

For this purpose, the adsorption or adsorption capacity of the chemical compound in question is reduced, which takes place by splitting off its functional groups and / or by partial oxidation and is explained in more detail below.

If the chemical compounds are also high-boiling, the compounds responsible for the odor emission are equally divided into smaller fragments beforehand by splitting off functional groups that cause the high boiling point and / or subjected to partial oxidation.

The well-known alcohol group can be mentioned as an example, because it can form hydrogen bonds that greatly increase the boiling point. If you only split off the OH group from a compound, then this is sufficient for the boiling point to drop significantly and noticeable adsorption no longer occurs.

A compound is preferably only split at the most unstable point and two individual molecules are created from it.

Alternatively, a functional group can be changed or split off. This usually eliminates the odor. The connection does not have to be completely split.

With this method, surface-active substances, i.e. substances with a large internal surface, are used. Special forms of aluminum oxide or titanium oxide are preferred, the latter being particularly preferred because it is acid-stable.

With the surface-active substances, i.e. substances with a large internal surface, e.g. aluminum oxide or titanium oxide or mixtures thereof, it is possible to largely split compounds even at low temperatures between 200 ° C and 400 ° C.

Many compounds can be totally oxidized at 400 ° C. In the case of thermally stable compounds, carbon is most likely left over, which can be completely oxidized to CO2 by occasional bake out at 450 ° C.

The point is to run the cleaning at the lowest possible temperature, where there is no coking, in order to get by with the lowest energy consumption.

In odor applications - as already mentioned - it is seldom the case that these exhaust gases have a high energy content. If you only have to heat up to 200 ° C - 300 ° C instead of, for example, 800 ° C, this is a great advantage due to the energy savings. That is an essential aspect of the invention.

• Das Verfahren und die Vorrichtung können zum einen alleine ausgeführt bzw. eingesetzt werden, d.h. eigenständig und unabhängig von weiteren Reinigungsverfahren bzw. weiteren Vorrichtungen. Der chemische Stoff bzw. die chemischen Stoffe resp. das Gas der Geruchsemission wird / werden so weit gereinigt, dass das angestrebte Ziel vollständig oder weitgehend erreicht wird, also die Geruchsemission vollständig oder weitgehend beseitigt ist. Der insoweit nicht abgereinigte Teil des Gases kann Reste von Kohlenwasserstoffen, Kohlenstoffmonoxid CO und anderem enthalten, aber gleichwohl in Bezug auf die Reduzierung der angestrebten Geruchsemission als befriedigend angesehen werden.

The invention provides two possibilities for this:

• On the one hand, the method and the device can be carried out or used alone, that is to say independently and independently of further cleaning methods or further devices. The chemical substance or the chemical substances resp. the odor emission gas is / are cleaned to such an extent that the desired goal is fully or largely achieved, i.e. the odor emission is completely or largely eliminated. The part of the gas that has not been cleaned off may contain residues of hydrocarbons, carbon monoxide, CO and others, but can nevertheless be regarded as satisfactory in terms of reducing the desired odor emission.

If the total concentration of the part of the gas that has not been cleaned up, i.e. that of the part of hydrocarbons that has not been cleaned up, carbon monoxide, is so low that you can use the partial cleaning is below a legally prescribed emission limit value, this independently and independently used technology is a tried and tested option for this reason alone. In addition, the odor is reduced or eliminated.

On the other hand, the aforementioned first, independent system can be used as a pre-cleaning stage. For example, the method and the device can be connected upstream of an RTO system or a rotor concentrator in order to destroy the high-boiling compounds so that they no longer represent a problem in further cleaning. This ensures that there is no further impairment of the cleaning performance in the downstream cleaning stage.

So if you split these odorous substances in advance in such a way that they do not result in high-boiling substances or high-boiling substances lose their high-boiling properties, the substances remaining after this cleaning process can then completely split off in an RTO system, for example, thereby achieving the advantage that the RTO system can continue to clean everything that is fed to its combustion chamber. Combustion takes place completely to form CO ₂ and water. Thus, only a pre-cleaning is required, by means of which the high-boiling substances are converted into non-high-boiling ones. This is exactly what the present invention accomplishes. The high-boiling substances are split or changed to such an extent that they are no longer high-boiling.

The invention can thus be used individually, detached from a further exhaust gas or exhaust air purification system, for example an RTO system, in order to remove only the odorous substances. As a result, a self-sufficient system is created. On the other hand, the invention can also be part of an integrated exhaust air purification with several processes in series.

The invention is therefore designed in accordance with the above explanations to split odorous substances by means of its method and its device.

The odorous substances have functional groups and are often strongly adsorbing substances.

Splitting means breaking a bond. For example, a molecule consists of several atoms that are connected to one another via bonds. In the invention, a connection is split. In this way, two or more molecules are created from one molecule. The resulting molecules no longer represent the same compounds.

Adsorbent substances are known to the person skilled in the art.

The adsorbing substances include, for example, ammonia or phenol. In the following, they will be discussed as “pars pro toto” in comparison to all odor-emitting substances. Both substances are odorous substances that are covered by the invention in the same way, although they are very different in terms of their boiling properties. The invention is therefore able to reduce the odor nuisance even with such conflicting substances.

Phenol is a so-called high-boiling substance because it only boils at 181 ° C. Phenol continues to adsorb very strongly because two other effects are relevant, namely on the one hand the polarity of a compound; the more polar a chemical compound is, the more it adsorbs; this is especially true if the compound can form hydrogen bonds, i.e. carries an OH group like phenol. On the other hand, phenol is an aromatic alcohol; due to the aromatic ring, the electrons are delocalized; this has an influence on the OH bond. Therefore, phenol adsorbs very strongly.

Usually at least 98% cleaning performance is achieved in an RTO system in a three-bed system for a substance with a molecular weight such as phenol or with a boiling point of around 180 ° C to 200 ° C. However, with phenol, if the raw gas temperature is very low, e.g. below 50 ° C, the cleaning performance drops to about 90%; At a raw gas temperature of 100 ° C, around 95% cleaning performance is still achieved, but a higher cleaning performance can hardly be achieved. In this example of phenol, a maximum cleaning performance of around 95% is achieved even with a three-bed RTO system, although it should be possible to achieve 98% purely in terms of boiling point. But phenol adsorbs more strongly because phenol is a polar compound with high volatility.

The person skilled in the art naturally also knows that in addition to the aforementioned aspects of the high-boiling property, the charge distribution and the volatility (volatility) also play a role. This can best be measured using the evaporation rate. The evaporation rate of a molecule is usually given in comparison to another molecule; here the time factor is included, which is given as a number. There is no need to explain that different numerical values have to be taken into account for different substances; the faster the substance evaporates, the higher the volatility number.

On the other hand, the person skilled in the art is also aware that high-boiling substances should evaporate slowly at a low temperature or have a low vapor pressure and still very much are volatile and can evaporate quickly; this would not be expected purely from the point of view of boiling point or vapor pressure, but it can result from high volatility. All of this is in turn related to the surface tension and the shape of the molecule, whether the molecule is roughly spherical or whether it is a stretched molecule.

The ammonia also mentioned above is a poisonous and strongly smelling gas. The reduction of NH ₃ is often prescribed by law (see also BImSchG, TA-Luft, GIRL). Ammonia is readily soluble in water. In principle, ammonia is not a high-boiling substance. Ammonia has a boiling point well below 0 ° C and is therefore gaseous at room temperature; nevertheless, ammonia adsorbs on surfaces. If ammonia is to be cleaned in an RTO system, for example, the cleaning effect depends on whether the exhaust gas is dry or moist; dry ammonia hardly adsorbs.

In the case of a moist exhaust gas, as is the case, for example, in mechanical biological waste treatment systems, the ceramic surface is always moist due to the exhaust gas moisture due to the heat exchanger. In the lower area, where it is cool, water vapor is sufficient, which is adsorbed on the ceramic and the ammonia dissolves in the adsorbed water or ammonia binds to the adsorbed water. But even then, ammonia only achieves a cleaning performance of 95% instead of a targeted cleaning performance of 99.8%. This is due to the good solubility of ammonia in water and the polarity.

Likewise, dust deposits can adsorb other substances or aerosol deposits can absorb other substances and thus lead to a significantly increased adsorption / desorption effect.

The above explanations show that and why conventional exhaust gas or exhaust air purification systems only achieve limited results with the reduction or even elimination of odor emissions. All of this is achieved by the present invention, which, however - as the example of ammonia shows - is not restricted to high-boiling compounds.

With regard to the reduction or elimination of odor pollution through splitting, the following should be mentioned: Most substances that emit an odor have a functional group.

The functional group can be one of hundreds of different groups, such as an aromatic ring (-aryl group) or it is an alcohol group (-OH group) or carboxylic acid group (-COOH group) or thiol group (-SH group) or es is a primary, secondary or tertiary amine (-NH ₂ , -NHR or -NHR1R2 group) attached to a hydrocarbon structure.

If such a functional group is split off from a molecule at a low temperature, it is similar to a catalytic reaction, only with the crucial difference that noble metal or Cu-Mn catalysts have a higher cleaning performance at the beginning, but can be poisoned very quickly. because they are very sensitive, for example to larger molecules, hydrothermal aging, sulfur or halogen compounds and a large number of inorganic elements such as heavy metals, phosphorus, sodium, potassium, arsenic, lead, mercury and many more.

The poisoning does not occur, or does not occur irreversibly, with the use of substances or substance mixtures such as aluminum oxide or titanium oxide, already summarized above, because these substances are each very inert. TiO ₂ is also not sulfated _{by SO 3.}

However, somewhat higher temperatures are required for the cleavage of functional groups than with the noble metal catalyst. The temperature can still be kept relatively low because many compounds can be cleaved at low temperatures such as 200 ° C.

200 ° C - 300 ° are sufficient for most applications. At temperatures of up to 450 ° C., almost every chemical substance undergoes the splitting of its functional groups, which is carried out according to the invention, into substances that are not adsorbent or are significantly less adsorbent.

This is usually accompanied by partial oxidation.

This means that total oxidation is not necessarily the aim, because the splitting or partial oxidation is sufficient to remove odors and / or reduce the tendency to adsorb. Short-chain hydrocarbons and carbon monoxide are a common breakdown product.

If the method is thus used as a pre-cleaning, the remaining hydrocarbons and the carbon monoxide can be cleaned in a conventionally known manner, for example in a subsequent RTO system.

If, on the other hand, the process is used as a stand-alone system that is independent of other cleaning systems, then in a very large number of cases the concentrations of residual hydrocarbons and carbon monoxide are the same be low that after this split there is no emission problem with regard to these residual values, but in any case the odor is reduced or completely eliminated.

In the case of high-boiling substances, the splitting off of functional groups of the chemical substance or molecule in question means that the boiling point drops because at least two smaller molecules are formed.

The original functional group does not remain in its original form either, because it also changes when it is split. The polarity and tendency to adsorb also change.

The method means that regardless of whether substances causing high-boiling or non-high-boiling odors are affected, the splitting of its functional groups carried out according to the invention in almost every chemical substance leads to substances that are not adsorbed or are significantly less adsorbent.

It is sufficient if the strongly adsorbing effect is lost, regardless of which and how many fragments are formed.

The catalytic effect at the mentioned temperature range of 200 ° C to 450 ° C is achieved by the large surface area, which is a combination of inner and outer surface. These highly stable compounds with a large surface area include the aforementioned aluminum oxide and titanium oxide, which are also known as catalyst supports because they are used as supports for noble metal or metal oxide catalysts because of their inertness and large internal surface area. Of course, the invention is not restricted to this.

Any related connection is possible. For example, compounds from the groups of silicate ceramics, magnesium oxide, zirconium oxide, zirconium oxide-reinforced aluminum oxide, aluminum titanate, titanium dioxide, silicon oxide, carbide, nitride are possible, to name but a few examples. But those skilled in the art will also include fiber-ceramic composites and metal matrix composites in their considerations.

The person skilled in the art is aware that all catalytic systems are used to convert hydrocarbons, usually> 99.9%, into CO ₂ and water when cleaning exhaust air. However, this is not necessary at all for the purposes of the present invention. Therefore, there is no need to use expensive precious metal catalysts or other oxidation catalysts, for example, which could do that with a short service life. Rather, robust substances or substance mixtures, i.e. substances with a high surface area, are used. These substances may not create total oxidation, but rather create a few intimate bond breaks at most. This is sufficient, however, as far as the odor is eliminated, or if the odor has been converted from a very unpleasant odor into a tolerable odor. An essential aspect is that the adsorbing properties are lost.

Well-known exhaust gas or exhaust air purification systems, such as RTO systems, lack the high cleaning power of adsorbent substances. Otherwise you could always use an RTO system to remove odors. If adsorbing substances are involved, the cleaning performance can also drop to 40%. In this case in particular, it is interesting to have a pre-cleaning system according to the invention with which, among other things, the high-boiling compounds are split so that they are no longer high-boiling compounds. The remaining substances can then be fed to the RTO system in order to achieve the high cleaning power related to this.

According to the invention, a substance or a mixture of substances with a large inner and / or large outer surface is used.

This can take place, for example, in the form of a bed or a layer applied as a washcoat on a ceramic honeycomb carrier, the odor-emitting substance being brought into intensive contact with the substance or the substance mixture at a temperature of 200 ° C to 450 ° C, whereby the strong adsorbing substances, whether because of their polarity, their molecular weight, their low volatility or their ability to form hydrogen bonds, are converted into non-adsorbing substances or substantially less adsorbing substances by splitting off functional groups and / or partial oxidation. This results in the desired effects of reducing or eliminating odor emissions and lowering the tendency to adsorb.

The substance mixture has a large inner and / or large outer surface and can be achieved by the aluminum oxide or titanium oxide described as an example.

Substance mixture within the meaning of the invention is a combination of two or more substances which do not form a connection with one another. There is no reaction between the substances. The term “mixture” can be used as a synonymous term.

There can also be a preparation.

The mixture of substances is either in the form of a bed or a washcoat on a monolithic carrier with a honeycomb structure.

The substances in the mixture have a large internal surface.

A large internal surface is given when the substance has far more than 10-20 m ² per gram of substance surface. Large internal surfaces have, for example, 100-1000 m ² / gram surface.

The inner surface is given by the fact that the substance has porous structures. The adsorbing and / or high-boiling substances can penetrate and diffuse into these structures.

The molecules can react on the surface of the porous structure of the substance and they are split as a result.

If the reactions are to be accelerated, a particularly large total surface area is required. The easiest way to achieve this is to provide a large internal surface. This achieves a large area in a small space.

In an alternative embodiment, in the case of a substance that does not have a large inner surface, the outer surface can be enlarged.

This can be achieved, for example, by grinding or crushing a substance. This makes the larger surface of the particles obtained usable.

A further embodiment of the invention can be a system with small pellets, which also result in a large surface. A structure made of pellets can be used here, because the small pellets produce a large outer surface in addition to the inner surface.

The preferred aim in this respect is that both the inner surface and the outer surface should be as large as possible.

Yet another embodiment of the invention takes up the following idea: In order to make the method more dust-resistant due to the use of such substances, it is preferred to use a honeycomb structure and to apply the material as a coating as a washcoat.

This creates a structure made of honeycomb bodies that are coated on the surface.

The honeycomb body then has a large outer surface. In the honeycomb body, the surfaces of the inner channels of the honeycomb body are also to be added to the surface. A large outer surface and a large inner surface can be brought about with the honeycomb body. In its interior, an enlargement of the material inner surface and, in addition, an enlargement of the outer surface is achieved by the ceramic carrier (honeycomb body).

If, for example, a ceramic honeycomb with a dimension of 150 × 150 × 300 mm with 60 × 60 channels is used, this results in 1000 square meters per cubic meter of external surface. The result has to be multiplied by the inner surface of the washcoat.

If the washcoat is 200 m ² per gram and if there is about 100 g per element, the result is 147 elements per cubic meter. This results in a ^{surface area of 2.8 million m 2} / cubic meter of ceramic honeycomb.

The honeycomb body should preferably only be used in conjunction with the washcoat.

The production of the honeycomb from pure titanium oxide or aluminum oxide is not possible on an industrial scale, but mixtures of Clayton and aluminum or titanium oxide powders, for example, could be extruded.

The passages in the honeycomb body are not clogged so much by the dust because a laminar flow prevails in the honeycomb body. Depending on whether the exhaust gas contains dust or not, you can choose the appropriate geometry.

The use of activated carbon honeycomb is also considered suitable. Clayton is mixed with activated charcoal and extruded.

A honeycomb can also be produced from any other material than the aluminum oxide and titanium oxide mentioned by way of example.

According to the invention, a ceramic honeycomb is not absolutely necessary as the base body, which is then coated. It is equally possible to produce a color from the metals mentioned without a coating.

With and without a honeycomb body, the goal is to select the mixture with a large inner or outer surface to achieve such a substance composition that enables the elucidated separation of functional groups.

• Die Vergrößerung der Fläche wird benötigt, da das Gas, der Geruchsstoff, einen Weg durch die Strukturen finden muss. Wenn man Substanzen der vorbeschriebenen Art einsetzt, kann das Gas durch die vielen Zwischenräume zwischen den Pellets, den Wabenkörpern, den porösen Strukturen der Substanzen, d.h. ihren Kanälen, zwischen den Phasen etc. hindurch diffundieren bzw. strömen.

Even if all the details of the physical and / or chemical processes involved in the elimination of functional groups have not yet been fully clarified, the applicant assumes the following relationships:

• The enlargement of the area is needed because the gas, the odorous substance, has to find its way through the structures. If substances of the type described above are used, the gas can diffuse or flow through the many spaces between the pellets, the honeycomb bodies, the porous structures of the substances, ie their channels, between the phases, etc.

It goes from bottom to top or from the side, from left to right, or from top to bottom.

The odorous gas flow diffuses or flows through the mixture and its interstices or whatever channels.

Due to the temperature described above, the fusion becomes very strong. When a molecule flows through the mixture, it does not stay on this route due to the thermal movement. The molecule is pushed back and forth and repeatedly slides into one of the gaps or channels and "gets lost" there.

The molecule penetrates the channels and at some point touches the surface of the mixture. The molecule hits an active surface there. The molecule is briefly held on this active surface and the molecule is cleaved.

The cleavage is therefore initiated when these molecular particles pass through the channels or interstices of the mixture. The molecule strikes the solid matter of the substance.

The molecules don't just hit. Rather, they are absorbed in or on active areas on the solid of the substance material.

In this context, reference is made to the reaction of the molecule, e.g. R-OH, with an oxygen molecule O ₂ : A molecule in the exhaust gas is retained by the surface, then an RH and H ₂ O as well as a free O radical can arise _{through reaction with O 2} , which reacts with another R-OH to form RH and H _{2 O.} The reaction is now complete. The rest again results from the binding site.

The split-off molecule, which is now less strongly adsorbed and has lost, weakened or changed its odor, migrates back into the exhaust gas flow and continues to flow. But this is already the separated molecule.

The split off molecule can react once more with the surface of the mixture and can be split off again.

In this way, the functional groups are split off from the molecules. The olfactory part of the molecule is thus split off.

For example, when thiols are cleaved, two molecules are formed, the alkyl radical that connects to the H radical of the -SH group and SO2, which is formed from the S of the -SH group and O2. The SO ₂ has a much higher odor threshold than a thiol. As a result, when thiols are converted into SO ₂ and an alkane, the odor concentration decreases sharply.

The underlying mechanism can be explained as in catalysis. In order to get from starting materials to products, a reaction path can be followed. Educts can have a lower or higher energy level than the products, depending on which one speaks of an endothermic or exothermic reaction. If starting materials and products are stable, the transition state is always higher than the highest of the two energy levels.

A catalyst can now enable a new reaction path with a significantly lower energy transition state by stabilizing it.

By providing a large inner and / or outer surface, a second reaction path is possible, which requires a significantly lower activation energy. As a result, the bond is split at a much lower temperature.

Figure list

The invention is further explained with reference to the following exemplary embodiment, to which it is of course not restricted.

• - 1: die Vorrichtung zur Durchführung des Verfahrens zur regenerativen thermischen Oxidation (RTO) in Turmbauweise,
• - 2: die Vorrichtung zur Ausführung des Verfahrens mit einem rekuperativen Wärmetauscher und
• - 3 eine Vorrichtung zur Durchführung des Verfahrens zur regenerativen Abgasreinigung mit zwei nebeneinander angeordneten Wärmetauschern und einer zentralen Heizung zur Zuführung von Wärmeenergie.

Here show:

• - 1 : the device for carrying out the process for regenerative thermal oxidation (RTO) in tower construction,
• - 2 : the device for carrying out the process with a recuperative heat exchanger and
• - 3 a device for carrying out the method for regenerative exhaust gas cleaning with two heat exchangers arranged next to one another and a central heating system for supplying thermal energy.

1 shows a device for regenerative exhaust gas purification, with an exhaust gas flow 1 .

the 1 has two heat exchangers 2 on, in the middle of which is a substance 4th is shown. The substance 4th is preferably as a bed or as a ceramic honeycomb carrier 9 educated.

Each between a heat exchanger 2 and the substance 4th is a heater each 10 intended for the introduction of thermal energy.

In 1 is a system of conduits 11th intended. The exhaust gas of the exhaust gas stream 1 is via a pump 12th in the system of conduits 11th introduced.

In top view of the 1 is at the top and at the bottom of the lines 11th one valve each 13th arranged.

Alternatively according to the arrows 13th and 14th becomes the exhaust 1 according to arrow 13th towards the valve 15th the line 11th promoted.

The same applies to the exhaust gas 1 that on the line 11th in the direction of the arrow 14th the valve 16 is fed. Via the valve 15th is exhaust gas to the upper heat exchanger 2 ; 17th .1 supplied.

In contrast, the exhaust gas alternates 1 according to the arrow 14th the valve 2 ; 16 fed.

Via the valve 2 ; 16 becomes the exhaust 2 in the heat exchanger 2 18th introduced.

Based on the respective valve 15th ; 16 the exhaust gas in the associated heat exchanger 2 ; 17th introduced.

The adsorbent contained in the exhaust gas is attached to the heat exchanger 2 ; 17th and 2 ; 18th adsorbed.

The adsorbent substance in the exhaust gas 1 is on the respective exhaust gas inlet side 7th of the respective heat exchanger 17th ; 18th adsorbed.

At the respective exhaust gas outlet side of the heat exchanger 17th ; 18th becomes the adsorbent of the exhaust gas 1 after the exhaust gas has emerged from the exhaust gas outlet sides 8th the heat exchanger 17th ; 18th is the respective exhaust gas flow 1 from the respective heaters 10 Thermal energy 3 fed. Following the supply of heat, the exhaust gas flow 1 into a substance 4th introduced having a large inner surface 5 has the substance 4th is a mixture of substances that has a large internal surface area.

The substance 4th is preferably kept in a bed. The substance 4th can also be arranged in a ceramic honeycomb carrier.

Alternatively, the substance can also be a set of pellets. The substance can also be a ceramic honeycomb carrier on which a wash coat is applied.

Alternatively, the substance can also be extruded in a mixture with clay in the form of a ceramic honeycomb.

The one in the exhaust 1 The covered absorbent material comes inside the substance 4th in substance channels 19th in contact with substance material.

When the adsorbent with the material of the substance 4th comes into contact, the adsorbent splits off functional groups.

When the adsorbent comes into contact with the material of the substance 4th the adsorbent is at least partially oxidized.

That in the heat exchangers 17th ; 18th and in the channels 19th the substance 4th purified clean gas 20th is excreted into the atmosphere.

the 2 shows the device for carrying out the method with a recuperative heat exchanger 21 that has a clean gas path 22nd , as well as an exhaust path 23 includes.

In the 2 becomes the exhaust 1 with the help of the pump 12th over the line 11th the exhaust path 23 fed.

About the further line 11th in which the heater 10 is arranged, the exhaust gas 1 the substance 4th fed.

In terms of substance 4th refer to the related paragraphs in 1 referenced. According to the 1 the substance is preferably in a bulk 9 arranged and includes the substance channels 19th .

Over the line 11th the exhaust gas cleaned with the help of the substance becomes 1 in the clean gas path 22nd initiated and as clean gas 20th released into the atmosphere.

In the 3 becomes the exhaust 1 about the pump 12th over the lines 11th Heat exchangers 17th and 18th fed. In the ducts carrying the exhaust gas 11th are valves 15th shown.

The two heat exchangers 17th and 18th each have a separate exhaust gas inlet side 7th on, through which the unpurified exhaust gas enters the heat exchanger 17th ; 18th is introduced.

In top view of the 3 adjoins the respective exhaust gas outlet sides 8th the heat exchanger 17th ; 18th one substance each 4th at.

Both substances correspond in structure and function 4th the for 1 described substance 4th .

In the representation of the 3 is roughly midway between the two substances 4th the heating system 10 arranged. The heating system 10 carries both substances 4th the 3 Thermal energy 3 to.

According to the 1 are also used in the 3 the two heat exchangers 17th ; 18th and the respective associated substances 4th each with the exhaust gas 1 loaded.

After the exhaust gas has been cleaned 1 through the heat exchanger 17th ; 18th and the substances 4th becomes the clean gas 20th released into the atmosphere.

Example 1:

This example relates to a pilot test which was carried out by the applicant and relates to the production of foods and here again various flavorings which are produced from yeast extracts. The flavors are used, for example, for soup packs. These flavors ensure that the soup tastes like meat. In reality, however, the soups contain yeast protein with a modified taste due to the Maillard reaction and no meat. Yeasts are inexpensive protein-rich substances that can be changed into thousands of different flavors by means of the Maillard reaction and at the same time also form odor-active substances with a low odor threshold.

The applicant has started a pilot test and has seen that, especially when the concentrations are so low and the compounds are high-boiling, it cannot be ruled out that instead of the usual 99.8% cleaning performance, the non-adsorbent Substances with the three-bed systems used in the RTO system were achieved, with the reduction of odorous substances only an efficiency of between approx. 30% to a maximum of approx. 40% was achieved for such odorous substances.

Example 2: Odor-laden exhaust gas from the fragrance / flavor industry, large volume flows of up to several 100,000 Nm ³ / h with a low pollutant load of a few mg / Nm ^3, e.g. 10 - 50 mg / Nm ³ but with 10 ^ 5 to 10 ^ 6 GE / m ³ .

Example 3: Exhaust gas containing hazardous substances from tire production for which lower emission limit values are to be set than for the TOC in general because of the carcinogenicity and mutagenicity as well as the teratogenic effects, whereby the exhaust gas also has a volume flow of up to several 100,000 Nm ³ / h and TOC concentrations of only 100 has up to 500 mg / Nm ³ .

List of reference symbols

1

exhaust

2

Heat exchanger

3

Thermal energy

4th

substance

5

inner surface of the substance

6th

medium

7th

Exhaust gas inlet side

8th

Exhaust gas outlet side

9

Bulk

10

heater

11th

management

12th

pump

13th

Arrow (up)

14th

Arrow (down)

15th

Valve (top)

16

Valve (below)

17th

Heat exchanger (top)

18th

Heat exchanger (below)

19th

Substance channel

20th

Clean gas

21

Heat exchanger

22nd

Clean gas path

23

Exhaust path

Claims (11)

Process for the splitting of strongly adsorbing substances for odor elimination and for the suppression of the adsorption effect with regenerative ones Air purification systems characterized by elimination of functional groups and / or partial oxidation in not or less adsorptive substances, as well as in non or slightly odorous substances in that a these substances containing exhaust gas at a temperature of 200 ° C to 450 ° C with a substance or a substance mixture with large inner and / or outer surface is brought into intensive contact. Procedure according to Claim 1 characterized in that the substance or the substance mixture is designed with a high internal and / or external surface in the form of a bed or as a washcoat layer applied to a ceramic honeycomb body. Procedure according to Claim 1 characterized in that the substance used or the mixture of substances with a high internal and / or external surface preferably consists of highly porous aluminum oxide, titanium oxide, or mixtures thereof. Procedure according to Claim 1 characterized in that the substance used or the mixture of substances with a high inner and / or outer surface, preferably from highly porous aluminum oxide, titanium oxide, or mixtures as powder with clay clay or other extrudable substances, are extruded into honeycomb bodies, burned and used for the purposes mentioned. Procedure according to Claim 1 characterized in that the temperature required for the splitting or partial oxidation of the strongly adsorbing substances in the exhaust gas is achieved through the release of energy during the partial oxidation or is partially or completely provided by external energy. Procedure according to Claim 1 characterized in that if the recuperative heat exchanger is used, it can be brought to 400 ° C - 450 ° C by varying the cycle time in order to free it pyrolytically from any organic deposits. Device for splitting strongly adsorbing substances to suppress the adsorption effect in regenerative exhaust air purification systems, characterized in that in this the exhaust gas with strongly adsorbing ingredients at a temperature of preferably 200 ° C to 450 ° C with a substance or a mixture of substances with a high internal surface in intensive contact is brought, whereby the strongly adsorbing substances are changed by splitting off functional groups and / or partial oxidation so that they no longer or significantly less adsorb. Device according to Claim 7 , characterized in that the substance used is designed in the form of a bed or as a washcoat on a ceramic honeycomb body or as an extruded honeycomb body. Device according to Claim 7 , characterized in that the temperature required for the cleavage and partial oxidation is achieved by shifting heat with the help of a regenerative or recuperative heat exchanger, whereby the remaining energy contribution required for this can come from partial oxidation or from external energy introduced, regardless of the form. Device according to Claim 7 , characterized in that the recuperative heat exchanger can be a fixed bed, ceramic honeycomb bed, fluidized bed or rotary or cyclone heat exchanger. Device according to Claim 7 , characterized in that the recuperative heat exchanger can be brought to 400 ° C - 450 ° C by varying the cycle time in order to free it pyrolytically from any organic deposits.

Images