Gas cleaning and purification

Gas Cleaning and Purification. Gas cleaning means the removal of impurities existing in the form of suspended liquid or solid particles, such as vapors, mist, fog, smog, smoke or dust. The impurities might also include gaseous substances that are objectionable or obnoxious, and their removal is usually called purification... 

Fain, D. E. Roettger, G. E. Coal Gas Cleaning and Purification with Inorganic Membranes Trans, of the ASME Journal of Engineering for Gas Turbines and Power, 115 (July 1993) 628-633. 

Foaming is usually caused by contamination of glycol with salt, hydrocarbons, dust, mud, and corrosion inhibitors. Remove the source of contamination with effective gas cleaning ahead of the absorber, improved solids filtration, and carbon purification. 

Wafers were prepared, sulfided and evacuated (2 h at 673 K) as described above. The temperature was then set at 423 K and 80 kPa of purified deuterium (Air Liquide, N28) was admitted into the cell. The purification procedure consisted of passing the gas through a moisture filter (Chrompack Gas Clean 7971), an oxygen filter (Chrompack Gas Clean 7970) and a liquid nitrogen trap. 

The C02 gas quality has significant impact on the capture cost by this technology, and uncertainties on the future regulatory requirements of C02 quality for its transport and storage has influence on the process configuration of the oxy-combustion plant, gas cleaning unit performance, overall C02 recovery capacity and on the energy requirements for C02 compression and purification. 

Dunn and Stich [78] and Dunn [79] have described a monitoring procedure for polyaromatic hydrocarbons, particularly benzo[a]pyrene in marine sediments. The procedures involve extraction and purification of hydrocarbon fractions from the sediments and determination of compounds by thin layer chromatography and fluorometry, or gas chromatography. In this procedure, the sediment was refluxed with ethanolic potassium hydroxide, then filtered and the filtrate extracted with isooctane. The isooctane extract was cleaned up on a florisil column, then the polyaromatic hydrocarbons were extracted from the isoactive extract with pure dimethyl sulphoxide. The latter phase was contacted with water, then extracted with isooctane to recover polyaromatic hydrocarbons. The overall recovery of polyaromatic hydrocarbons in this extract by fluorescence spectroscopy was 50-70%. 

In Japan, there is a project aimed at capturing the considerable volume of hydrogen gas which can be obtained as a by-product steel production. R D will focus on the purification process of fuel from coke oven gas to an acceptable level for fuel cell utilisation. METI, the Japan Research and Development Centre for Metals and Nippon Steel are working on the project with a 2003 budget allocation of 549 million. Japan also operates the 4C/.f project which aimsto develop an optimum coal gasifier for fuel cells and the establishment of gas clean-up system for purification of coal gas to the acceptable level for utilisation for MCFC and SOFC. The budget allocations for 2000-2003 total 4.6 billion. 

Development ofother fuels for feeding fuel cells (natural gas, methanol, bioalcohols, oil fractions etc.) relative to profitable and clean production, purification and infrastructure development. 

Kirkbride (1987) described the estimation of diazinon in human omental tissue (fatty tissue) after a fatal poisoning. In this method, the tissue was pulverized and extracted with acetone. After extract concentration and purification by sweep co-distillation and Florisil fractionation, diazinon was measured by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). After another fatal diazinon poisoning, diazinon was quantified by GC/electron capture detection (ECD) and GC/flame ionization detection (FID) by Poklis et al. (1980). The diazinon in human adipose, bile, blood, brain, stomach contents, kidney, and liver was recovered by macerating the sample with acetonitrile followed by the addition of aqueous sodium sulfate and extraction into hexane. Following an adsorption chromatography clean-up, the sample was analyzed. 

Plate-fin exchangers provide a very large heat transfer surface per unit volume and are relatively inexpensive per unit area. They are not mechanically cleanable and are ordinarily used only with very clean fluids. This combination of properties fits them very well for a wide variety of cryogenic applications, such as air separation helium separation, purification, and liquefaction liquefied natural gas production and separation of light hydrocarbons. They are also used in higher-temperature gas-to-gas services. 

For particle cleanup cyclones, impact separators, fabric and fiber filters, granular beds, and electrostatic percipitators for low-temperature gas cleaning have been widely used in the industry. However, for hot gas filtration with ceramic filters, the long-term durability, alkali corrosion, cleanability, thermal shock, and particulate penetration into filter media has been recognized as major concerns. Traditional bag filters are sensitive to high ten erature and hot particles, electrostatic percipitators have a relatively high cost of installation in smaller plants and multi-cyclone cleaners are not sufficiently efficient to meet the new purification demands. 

Air purification is a very important issue. Air cleaning devices are needed for respiratory protection (gas masks) and for removing CO, CO2, water vapour and trace amounts of VOCs and ozone from ambient air indoor office space (due to smoking, etc.) and in submarines or space crafts on long missions [2,6,7,18,31,64,71,110,125,126,132,251,260-264,598]. 

Off-gas purification. As a high-temperature process, any type of vitrification process will have to have a very effective off-gas cleaning system. In fact, besides the remote operation and maintenance technique, off-gas treatment will be among the most important waste-processing problems to be solved. The off-gas may contain volatile fission products, such as ruthenium and cesium, as well as aerosols and dust. Multistage systems will be required with wet and dry cleaning procedures to obtain an off-gas sufficiently clean for release to the atmosphere. 

S. Blumrich and B.H. Engler "Tlie DESONOX / REDOX-Process for Fuel Gas Cleaning. A Simultaneous Fuel Gas Purification Process for the Simultaneous Removal of NOx and SO2 respectively CO and HC", 1st Conf. Environmental Industrial Catalysis, Louvain-La-Neuve, Belgium,... 

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