DE3311100A1 - Novel process for gas purification - activation sorption - Google Patents

Abstract

The novel process for noxious gas separation, the so-called activation sorption, is based on the exploitation of mechanical activation of solids for dry separation of noxious gas from exhaust gases. The essence of the invention lies in the exploitation of the active states of solids produced by intensive mechanical stress, which active states are distinguished by the presence of deformations, faults and destruction of the crystal lattice. As a result of these changes in the state of order in the crystal lattice, the activated solids are unstable and have increased reactivity. They are thus in the position to chemically and physically bind noxious gases, some of which considerably pollute the environment such as, for example, SO2, SO3, H2S, F<->, Cl<-> and hydrocarbons, more rapidly and more productively (in the stoichiometric sense) than non-activated, conventionally used additives. The performance and economic efficiency of the novel process are, moreover, based on a further effect of the mechanical activation: stable agglomerates - likewise caused by the active state of the solids - are formed, the separation of which after binding the noxious gas is possible by simple mechanical dust removers. Binding the noxious gas is carried out most effectively directly in the activation reactor (vibratory mills or similarly functioning units). For large quantities of exhaust gas having noxious gas fractions, parallel connection of activation and ... Original abstract incomplete. <IMAGE>

Description

New gas cleaning method - activation sorption

Field of application of the invention The invention relates to a method for noxious gas separation in connection with simultaneous dust conditioning for the subsequent dust separation using the mechanical activation Phenomena that occur in solids, whereby under mechanical activation the Creation of deformations, defects and destruction in the crystal lattice of Solids due to intensive mechanical stress is to be understood.

With this so-called activation sorption, a process is presented with which the environmental pollution by harmful gases such as SO2, SO3, F, cr and various hydrocarbons can be reduced in an effective and economical manner can, as it is a purely dry process with lower costs than comparable Dry or wet processes can be carried out and, in addition, the use of existing ones Exhaust heat content allowed.

The new process can be used for all areas of application where harmful gases can be separated from the gas flow by solid-state reactions. this mainly concerns the cleaning of exhaust gases from coal-fired boilers (desulphurisation), Exhaust gases from coal, coke, oil or electrically heated smelting plants (H2S, SO2 # and F - separation), exhaust gases from waste incineration plants (separation of S02, H2S, C1, F), exhaust gases from the ceramic industry (separation of fluorine and SO2) and exhaust gases from various areas of industry, craft, the Agriculture and municipal operations for the separation of hydrocarbons (phenols, Aldehydes, etc.) also to avoid unpleasant odors.

State of the art The previously used methods for gas cleaning can be roughly divided into: 1. Process with recovery of valuable substances (gypsum, ammonium sulphate, Sulfuric acid, etc.) and 2. Process without recovery of valuable substances Those mentioned under 1. Processes usually first require a pre-separation of dust, which is usually the case electrostatic gas cleaning (EGR) is used. Then the Contamination of harmful gases, which leads to the production of valuable substances, either by wet mechanical / wet chemical Process with downstream dewatering and drying of the recyclable material as well Heating of the pollutant-free exhaust gases by means of "semi-dry" as a hybrid process or spray adsorption with downstream dry waste separation by EGR or filter and usually exhaust gas heating or by dry adsorptive processes with activated carbon or activated coke with regeneration of the adsorbent and further processing the harmful gases as rich gases (e.g. S02 to H25O4).

These methods are cost-intensive due to the outlay in terms of equipment. It can also be estimated that those caused by the legislature Measures to control harmful gases resulting in an overproduction of specific valuable substances lead and thus create an additional landfill problem.

In the case of the process mentioned under 2., the pre-separation of dust is used waived. In order to avoid the disadvantage compared to the processes with recyclable material generation (lack of In the case of these Process with significantly less equipment expenditure as close as possible to the stoichlometrically necessary amount of additive worked.

This is for desulfurization processes using "semi-dry" spray adsorption and subsequent dust separation # EGR or filter) possible.

For the sole use of chlorine and fluorine separation are suitable because of the reactivity of these two pollutant gases also purely dry additive processes with downstream dedusting of the exhaust gases.

The procedures, which are complex in terms of equipment, have a special position Cleaning / odor pollution through ion exchange reactions, with which predominantly Hydrocarbons are detected.

All pollutant gas separation processes in use are in common that they lead to unsatisfactory cost burdens. This is above all on the unsatisfactory stoichiometry of the process, the relocation of the Problem from the gaseous to the liquid state of aggregation, the use costly dust separation and the landfill costs.

Therefore there is no shortage of attempts to develop more effective methods. For this purpose, dry methods are particularly suitable, because they make them useful the heat content of cleaned exhaust gases becomes possible. As a detrimental effect with dry cleaning processes, however, the low reactivity has always been the case up to now between the reactants under the predominantly existing reaction conditions (short residence time, low noxious gas concentration, temperatures from 1500 C - 2500 C) off. To achieve the separation goals are therefore mostly multiple stoichiometric ratios between additive amount and harmful gas necessary, the lead to a double burden in terms of quantity and cost: in the process and for the Landfill.

The development efforts of various institutes and companies therefore focus particularly on improving responsiveness of additives. For example, there is a method from Lühr, Stadthagen (Patent applicant probably Mr. Dipl.-Ing.Margraf), the spherical rotor process describes the surface energy of the finest dust particles for binding pollutants and Uses dust agglomeration.

The present invention has similar but advanced features Objective by using mechanical activation.

The aim of the invention is to increase the responsiveness of the Additives under the given reaction conditions are predominantly chemical as well to achieve residual physical pollutant gas binding under stoichiometric conditions. Mechanical activation is used to increase the additive reactivity: due to intense mechanical stress, such as those caused by hitting and thrusting Mahigut load in vibrating mills is possible in the crystal lattice of the Regrind (here: the additives) deformations, imperfections, partial or total Creates destruction. According to a material-specific, definable state of order Striving Mahlgut / Addltlv is unstable and reactive due to the lattice changes. In contact with harmful gases, it reacts chemically by incorporating gas atoms and ions into the lattice, through the filling of lattice imperfections or through the formation of new material.

Aiming to quickly return to the old or a new ordered grid state Finding it back is beneficial to the reaction kinetics. The chemical reaction is going through the free enthalpy inherent in the additive as a result of the release of the lattice energies supports and accelerates.

In addition, harmful gas is physically connected to the extraordinarily large ones specific surfaces of the additives bound, which inevitably at the intensive mechanical activation arise.

The invention is based on the fact that already through the activation success the amount of flue dust usually present in the exhaust gas flow for sufficient binding of harmful gases (within the meaning of environmental protection legislation) is enabled. Continue to let through the mechanically generated, extraordinary reactivity waste materials such as the iron oxide-rich red mud from aluminum production for noxious gas separation activate from low-dust exhaust gases.

A side effect is that which is also caused by the active state Agglomeration tendency of the additive ground material, which despite the inacl; ivation as a result chemical and physical noxious gas binding is still pronounced for the subsequent separation of the powdery reaction products is used. In the of the order of magnitude of 0.3-0.05 mm leave agglomerates present themselves through simple mechanical separators (deflection chambers or centrifugal separators) separate from the exhaust gas flow and thus reduce the procedural and economic effort of the overall procedure.

Object and essence of the invention The invention is based on the object by integrating mechanical activation into the exhaust gas cleaning process the exceptional reactivity of activated solids / additives to To use noxious gas binding. There are two different ways of realizing the task Process routes in question: 1. Use of the activation reactor - multi-chamber vibration mills or similar aggregates specially designed for the function of activation sorption -directly as a pollutant gas binding reactor in connection with mechanical dust separators (see Figure 1), 2. the parallel connection of the activation reactor and reaction space for the binding of harmful gases. For this purpose, part of the additives is recycled and reaction products intended for multiple use. The dust separation the reaction products are carried out by mechanical or filtering dust collectors (see Fig. 2).

When using the procedure mentioned under 1., the occur comparatively more favorable reaction conditions because the reaction takes place immediately at the moment of the The emergence of the most active solid state, that is, it takes place quasi in the statu nascendi. In addition, the vibrating mass of reaction space, grinding bodies and additive ground material virtually optimal conditions for excellent reaction kinetics. Through the adjustable multiple loading of the solids also arises from the Reaction product is an activated material that has free enthalpy potential and surface energy binds additional harmful gas components and at the same time leads to agglomeration of the end product. As a result, the deposition can be carried out in this method manage the reaction products from the gas stream by simple mechanical dust extractors, i.e. through the intense mechanical stress drops the end product the reaction in the form of uniform spherical agglomerates. Fine or fine dust (less than 0.01 mm) virtually does not occur. With an agglomerate size of 0.03 - 0.05 mm experience the briquetted reaction products due to inertia forces (gravity and especially inertial forces) in the exhaust gas flow is already clearly differentiated Acceleration. This is sufficient for sufficient dust separation (in terms of environmental protection legislation). The centrifugal separators or deflection chambers that can therefore be used as dust extractors are in comparison with other dust collectors (wet mechanical systems, filtering separators or electrostatic precipitators) by far the handling, robustness, availability, Low maintenance, temperature sensitivity and, above all, low cost Separation systems. Your total costs (capital and operating costs) are of the order of magnitude lower by a factor of 10 than that of the other separator systems mentioned.

For the effective mechanical activation of additives, the below No. 3 143 756.7 used the invention applied for. This application relates to vibratory mills or similarly vibrating units with special moving (accompanying) Built-in components that prevent the grist from caking and the stress is substantially intensified.

These so-called rotary chamber vibratory mills are also used if the procedure mentioned under 2 is followed.

The parallel connection of the activation reactor and the corrosive gas binding reactor is especially useful for large amounts of exhaust gas.

When using this process variant, the disadvantage (compared to Process path 1.) the lower reaction kinetics due to a longer Verwellzelt of the activated additive in the exhaust gas flow is balanced out by circuit operation. the Using filtering dust collectors offers another option that Extend response time.

By a suitable procedure, for example by generating a significant difference in speed between additive addition and gas flow can be moreover increase the possibility of reaction between the reaction partners.

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Claims (7)

Claims rut 1. A process for separating harmful gases from any Exhaust gases through the use of mechanically activated solids, thus marked that the active state by changing the crystal lattice of the solids such as e.g. through deformation, distortion, generation of defects, partial or total destruction the grid is created. 2. The method according to claim 1, characterized in that for the mechanical activation of the solid-state additives, vibratory mills or in a similar manner vibrating aggregates are used. 3. A method for polluting gas separation according to claim 1 and 2, characterized characterized in that the noxious gas binding directly in the activation reactor, so during solids activation takes place. 4. A method for separating harmful gases according to claim 1 to 3, characterized characterized in that the solid reaction end products are obtained as stable agglomerates. 5. The method according to claim 4, characterized in that the forming agglomerated reaction end products by simple mechanical dust extractors be deposited from the gas stream. 6. A method for separating harmful gases according to claim 1 to 4, characterized characterized in that for binding the harmful gas directly, the predominantly present in exhaust gas streams Airborne dust can be used as activated additives. 7. A method for separating harmful gases according to claims 1 to 4 and 6, characterized in that waste materials alone or in addition to the pollutant gas binding from other product areas such as aluminum production (red mud) or the stone and earth industry (Limestone and dolomite dust) are used in activated form.