Exhaust gas cleaning

If a fabric filter is used, several precautions need to be taken in order to protect the filter medium as discussed in Section 4.5.1.3. These include using a high temperature cyclone or multicyclone 

The application of wet dedusting techniques causes a higher energy consumption, the necessity for water treatment prior to discharge, and the need to dispose or reeycle wet filter sludge. 

Operational data are given in Section 3.2.3.4. Current bag filters have air to cloth ratios between 2 1 and 3 1. The air to cloth ratio is the ratio of volumetrie airflow through the filter to the 

The costs for installing a new dust capture and filtration unit in an existing Polish EAF foundry using two 8.5 t/h melting furnaces are summarised in Table 4.42. Dust emissions have been reduced from 10 - 13 kg/h and 145 - 150 mg/Nm to 0.2 - 0.25 kg/h and 2.8 - 2.9 mg/Nm. There has also been a major reduction of difihise emissions from the melting shop. 

Constmction and assembly of doghouse housings over 2 furnaces 275000 

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Ce02 is contrasted with ZnO the surface formate on CeOz is stabilized by the coexistence of water vapor, where the selectivity to H2 and C02 only increases as a result of suppression of the backward decomposition of formate more than that of the forward decomposition by water vapor. This property of the Ce02 surface was modified by doping with a small amount (0.2 wt%) of Rh. The Rh/Ce02 catalysts have been commonly used as automobile exhaust gas-cleaning catalysts, on which the WGS reaction proceeds. 

Monolith reactor This type of reactor is used extensively for the abatement of automobiles exhaust emissions. The gas flows continuously through the reactor, whereas the catalyst is a continuous phase consisting of a ceramic support and the active phase, which is dispersed onto the support. The support is structured in many channels and shapes that achieve large catalytic surface at small volume. A typical application of monolith reactors is the exhaust gas cleaning. 

A direct application to chemical process technology of the principle of electric wind is in electrostatic precipitators (Leonard et al.,1983) and electrocyclones for size separation of particles in powder technology (Nenu et al., 2009). Electrostatic precipitators applied to exhaust gas cleaning have recently been reviewed 0aworek et al., 2007). A particularly interesting development is that of a small electrocyclone with a diameter of 75 mm (Shrimpton and Crane, 2001). With this device it was shown that the separation quality of the smallest size particles with a diameter below 38 pm doubled upon application of the electric wind. Later experiments performed with submicron silica particles demonstrated that classification of such particles is possible by use of an electrical hydrocyclone (Nenu et al., 2009). 

Monolithic catalyst carriers are state-of-the-art in exhaust gas cleaning, for example in automobiles, DeNOx or removal of VOCs. To minimize diffusion length and to increase the geometric surface area, monoliths with small-diameter channels have been developed which can be produced easily by extrusion, followed by calcination. In the past few years the application of monoliths in gas-liquid operation has been investigated intensively [10-13]. 

Catalytic combustion applications can be classified as either primary or secondary pollution control, that is, emissions prevention or emissions clean-up. The most common example of catalytic combustion for emissions clean-up is the catalytic converter in the exhaust system of automobiles. Catalytic combustion is also increasingly used for the removal of volatile organic compounds (VOCs) from industrial exhaust streams. The use of catalytic combustion in exhaust gas clean-up is discussed in other sections of this Handbook this section deals only with primary control applications. 

Expensive exhaust gas cleaning system (due to methylene chloride)... 

Easier exhaust gas cleaning (no methylene chloride as solvent)... 

Porous and thermally stable washcoating layer on mechanically strong support is an important component in both oxidative and three-way catalysts used for car exhaust gas cleaning. The washcoat provides a high and stable surface area for dispersion of the active component of the catalysts consisting of platinum and /or paladium. Usually for the preparation of this layer aluminas modified by La, Ce, Zr, Si etc. are used [1-3]. As it was shown in [4-6] the properties of modified aluminas depend on the method of introduction of the additives In this work we present the results on the preparation and study of model alumina systems modified by La, Ce and Zr as well as of monolith supports washcoated by optimal compositions of alumina and additives. 

The use of a liquid catalyst is new in the field of exhaust gas cleaning and there are many unanswered questions and unsolved problems. In this exploratory work, it will be shown that the application of molten eutectic salt mixtures as liquid catalysts might result in sufficiently... 

Ceria and alumina, which form the intermediate porous layer (the washcoat) between the mechanical support and the supported metals and promotors, are important components in three-way catalysts (TWC) used for car exhaust gas cleaning. Although basie studies have been published on such systems [1], the interactions which can exist between alumina and eeria and which in turn may affect the interactions between the supported metal and the washcoat [2], are not fully understood. In particular, the multiple roles attributed to ceria, like stabilization of the alumina [3], of the supported metals [4], like storage and release of oxygen [2], are veiy probably dependent on preparation methods, activation and reaction conditions. Therefore, selective characterization of each oxide in ceria-alumina can be useful for a better imderstanding of the role played by both alumina and ceria in TWC. The present work describes two "ehemical methods", the adsorption of carbon dioxide followed by IR spectroseopy and the temperature-progranuned reduction (TPR), which lead to an estimation of the surface extent of alumina and ceria respectively. 

Figure 10. Current technologies for the diesel engine exhaust gas cleaning 5.3. PEC System for NOjt Removal...

Some ion-molecular reactions were already discussed earlier. Thus, the positive ion conversion A+ -I- B -I- M AB+ + M was considered in Section 2.2.2 as a preliminary stage of the dissociative electron-ion recombination. Ion-molecular reactions not only make a contribution in the balance of charged particles but also provide plasma-chemical processes by themselves. Ion-cluster growth in dusty SiH4 plasmas and ion-molecular chain reactions of SO2 oxidation in air during exhaust gas cleaning are good relevant examples, which will be discussed later in the book. 

Plasma-Chemical SO2 Oxidation to SO3 in Air and Exhaust Gas Cleaning Using Relativistic Electron Beams... 

Plasma-Stimulated Combined Oxidation of NOx and SO2 in Air Simultaneous Industrial Exhaust Gas Cleaning of Nitrogen and Sulfur Oxides... 

An important advantage of plasma-assisted exhaust gas cleaning, especially in the case of power plant exhaust, is due to the possibility of simultaneous oxidation of SO2 and NOx to sulfuric and nitric acids. The products can then be collected in the form of non-soluble sulfates and nitrates, for example, in the form of the fertilizers (NH4)2S04 and (NH4)N03 if ammonia (NH3) is admixed to the plasma-assisted oxidation products (Pu Woskov,... 

Various waste and exhaust gas cleaning techniques are used in the foundry industry. Their principles are discussed in the BREF document for non-ferrous metal industries. The properties and emission levels of dust abatement systems are given in Table 3.32. A full discussion on the selection of the abatement technique, its applicability in the various foundry processes and the achievable emission levels is given as part of the techniques to be considered in the selection of BAT in Section 4.5. 

Exhaust gas cleaning increases the energy consumption. The dedusting of the exhaust gas, generates dust for disposal or re-use. The application of wet dedusting techniques lead to a... 

In recent years, people and their governments have become more and more concerned with the quality of the environment we all live in. This has resulted in an increased awareness of the importance of good and responsible pollution control practices. This in turn has meant a large increase in the number of exhaust gas cleaning systems being installed. The centre of any such system is frequently the absorber tower or scrubber itself. 

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