Sulfur control systems

Pollutants. The problems posed by ak pollutants are very serious. Within a museum, measures can be taken to remove harmful substances as efficiently as possible by means of the installation of appropriate filter systems in the ventilation equipment. Proposed specification values for museum climate-control systems requke filtering systems having an efficiency for particulate removal in the dioctyl phthalate test of 60—80%. Systems must be able to limit both sulfur dioxide and nitrogen dioxide concentrations <10 /ig/m, and ozone to <2 /ig/m. ... 

Emissions control systems play an important role at most coal-fired power plants. For example, PC-fired plants sited in the United States require some type of sulfur dioxide control system to meet the regulations set forth in the Clean Air Act Amendments of 1990, unless the boiler bums low sulfur coal or benefits from offsets from other highly controlled boilers within a given utiUty system. Flue-gas desulfurization (FGD) is most commonly accomphshed by the appHcation of either dry- or wet-limestone systems. Wet FGD systems, also referred to as wet scmbbers, are the most effective solution for large faciUties. Modem scmbbers can typically produce a saleable waUboard-quaUty gypsum as a by-product of the SO2 control process (see SULFURREMOVAL AND RECOVERY). 

The emission control system for LPG is the same as is used for gasoline fueled engines with the exception of the fuel metering system. No evaporative emission system is required. Both Pt—Rh and Pd—Rh catalysts are good for emission control of LPG fuel exhaust. Pt provides the lowest light off temperature for C Hg. The sulfur content of LPG is also very low so that Pd catalysts perform very well. 

Anodic Protection This electrochemical method relies on an external potential control system (potentiostat) to maintain the metal or alloy in a noncorroding (passive) condition. Practical applications include acid coolers in sulfuric acid plants and storage tanks for sulfuric acid. 

Calcined limestone or Ume reacts with sulfur oxides. They are then removed with a dry particulate control system. 

Oxides of sulfur react with copper oxide to form copper sulfate. Removal with a dry particulate control system follows. 

Sulfur dioxide reduction to achieve required emission levels may be accomplished by switching to lower-sulfur fuels. Use of low-sulfur coal or oil, or even biomass such as wood residue as a fuel, may be less expensive than installing an SO2 control system after the process. This is particularly true in the wood products industry, where wood residue is often available at a relatively low cost. 

Plant operators should aim at using fuel with less than 0.5% sulfur (or an emissions level corresponding to 0.5% sulfur in fuel). High-sulfur fuels should be directed to units equipped with SO, controls. Fuel blending is another option. A sulfur recovery system that achieves at least 97% (but preferably... 

A. Hausberger I think a sulfur-tolerant catalyst would definitely be an advantage in that the requirement for critical control of the sulfur removal system would be eliminated. If you can allow some sulfur to pass on through the methanator into the product gas, the amount of reagent or regeneration cost of the sulfur removal system would be reduced. As to what level of sulfur could be tolerated, that is a hard question to answer since I don t think that there is a sulfur-tolerant catalyst. 

A fuel processor for PEFC application contains sulfur removal, an ATR-enhanced UOB reformer, advanced shift reactors, a steam generation system, a product gas cooler, a PROX system, a gas compressor, an air compressor, an anode-off gas oxidizer, and a control system. Goal efficiency (LHV H2 consumed by fuel cell/LHV fuel consumed by fuel processor) is 69 to 72%. H2 concentration is presently >50% (dry). 

Most industrial operations today now have pollution control systems, like the one shown in this chemical plant, to reduce the levels of sulfur dioxide and oxides of nitrogen released to the atmosphere. (Maximilian Stock Ltd./Photo Researchers, Inc.)... 

When this is done, the calcium hydroxide is included in the melting furnace slag, and the unspent calcium carbide is either used or oxidized in the melting furnace. Little testing has been done to determine the actual fate of the sulfur. Most of it may be included in the slag, but it may also be emitted to the air as sulfur dioxide, or, for foundries with wet emission control systems, it may be dissolved in the water. 

In January and March of 1988, Radian Corporation made a comprehensive series of performance measurements on the air pollution control system at Modesto (47). As shown in Table 12, the measurements included chlorinated dibenzo-p-dioxins (CDD), chlorinated dibenzofurans (CDF), polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenols (PCB), total hydrocarbons (THC), ammonia, NOx, sulfur trioxide, sulfur dioxide, hydrochloric acid, carbon monoxide, and particulate matter. 

Acetylene hydrogenation. Selective hydrogenation of acetylene to ethylene is performed at 200°C over sulfided nickel catalysts or carbon-monoxide-poisoned palladium on alumina catalyst. Without the correct amount of poisoning, ethane would be the product. Continuous feed of sulfur or carbon monoxide must occur or too much hydrogen is chemisorbed on the catalyst surface. Complex control systems analyze the amount of acetylene in an ethylene cracker effluent and automatically adjust the poisoning level to prepare the catalyst surface for removing various quantities of acetylene with maximum selectivity. 

Amend the Clean Air Act to allow the burning to high-sulfur coal through use of intermittent control systems. 

The sulfur dioxide problem for example can be solved in a number of ways. The easiest way is by the use of intermittent control systems. However, EPA and Congress refuse to approve of this method. As a result, the requirements for low sulfur coal are increased by ten times over what they would be if intermittent control systems were allowed. The insistance upon the use of scrubbers is going to increase the cost of electricity by billions of dollars per year—all to be paid by the ultimate customers. ... 

Crushed bulk is the least acceptable type of solid sulfur. It is created when using earth-moving equipment to recover sulfur which has been allowed to solidify in sheet or vats. Obviously, the product is extremely dusty. Very few producers (Former Soviet Union, Iran) still ship crushed bulk. Most consumers refuse to accept shiploads even at significant price discounts due to dustiness, related contamination, and product loss. A U.S. patent was recently issued to d Aquin for a revolutionary solid sulfur unloading system in marine application which eliminates dust and controls acidity with most formed sulfur.12... 

Mix Production. The feed control system of the mix plant is integrated with the automatic controls on SAM. SAM automatically controls the sulfur-asphalt ratio and matches the production of SA binder to the aggregate feed rate. The SA binder is mixed with the aggregate between 116° and 160°C. This reduces the levels of emissions and produces mixes that are well coated and appear virtually indistinguishable from conventional asphalt mixes. 

GOGiNENi ET AL. Wet Scrubbing of Sulfur Oxides Air Pollution Control Systems... 

The Air Quality Control Systems (AQCS) using lime/limestone wet scrubbing have three basic types of chemical process equipment (1) scrubbers, (2) reaction tanks, and (3) solid-liquid separators, in addition to several auxiliary pieces of equipment such as pumps, demisters, and reheaters. The SO2 in the flue gas is transferred into the liquid in the scrubber, the sulfur in the liquid is converted to solid calcium sulfite, and calcium sulfate in the reaction tanks and solid calcium sulfite and sulfate are separated from the liquid and disposed from the solid-liquid separators such as clarifiers, vacuum filters, and ponds. 

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