Plant hydrocarbon emission

Aluminum reduction plants Materials handling Buckets and belt Conveyor or pneumatic conveyor Anode and cathode electrode preparation Cathode (haldng) Anode (grinding and blending) Particulates (dust) Hydrocarbon emissions from binder Particulates (dust) Exhaust systems and baghouse Exhaust systems and mechanical collectors... 

The behavior of these pollution roses is intuitively plausible, because considerable hydrocarbon emissions come from motor vehicles which are operated in both winter and summer and travel throughout the urban area. On the other hand, sulfur dioxide is released largely from the burning of coal and fuel oil. Space heating emissions are high in winter and low in summer. The SO2 emissions in summer are probably due to only a few point sources, such as power plants, and result in low average concentrations from each direction as well as large directional variability. 

Air emissions should be monitored regularly for particulate matter and fluorides. Hydrocarbon emissions should be monitored annually on the anode plant and baking furnaces. Liquid effluents should be monitored weekly for pH, total suspended solids, fluoride, and aluminum and at least monthly for other parameters. Monitoring data should be analyzed and reviewed at regular intervals and compared with the operating standards so that any necessary corrective actions can be taken. 

Losses of valuable components through waste streams The chemical analysis of various plant exit streams, both to the air and water, should indicate if valuable materials are being lost. Adjustment of air-fuel ratios in furnaces to minimize hydrocarbon emissions and hence fuel consumption is one such example. Pollution regulations also influence permissible air and water emissions. 

VOC emissions from service stations Hydrocarbon emissions from bulk gasoline plants and new terminal loading facilit Bulk gasoline terminals Open burning... 

Volatile emissions from vegetation include hydrocarbons other than isoprene and terpenes. Altshuller (1983) has compiled emission data available to him [mainly from Zimmerman (1979a,b)]. The emissions contained C2-C6 alkanes, various alkenes, and C6-C12 volatile organic compounds. Practically every deciduous plant and all the grasses studied emitted alkanes with ethane and propane dominating the mixture. Twenty to 50% of total hydrocarbon emissions, on average, consisted of alkanes. 

Biogenic hydrocarbon emission rates from individual plant species have been estimated experimentally by placing small plants or branches in enclosures and measuring the accumulation of emitted compounds. Extensive emission rate measurements have been reported for a relatively limited number of compounds isoprene and a number of the dominant monoterpenes. Isoprene does appear to be the dominant compound emitted from vegetation. 

Hydrocarbons (particularly aromates and polycyclic hydrocarbons, but also n-alkanes, isoalkanes, cycloalkanes as well as unsaturated hydrocarbons), which enter the atmosphere in the course of petroleum and natural gas exploitation, during their treatment, transportation, storing and utilization of products, are important sources of air pollution. In the developed industrial countries the portion of hydrocarbon emissions constitutes as much as 9% of the total amount of emissions [20]. Table 5.23 presents data concerning emissions of hydrocarbons from a hypothetical refining plant with a treatment capacity of 5 million t yr, related only to storage and transport of petroleum and by-products in the refining plant [21]. 

Although it is practically impossible to control hydrocarbon emissions from living plants and other natural sources, hydrocarbon emissions from automobiles can be controlled. Two means of control are in use at present. First, the spouts and hoses on gasoline pumps have been redesigned to prevent gasoline from entering the air. Second, catalytic converters that reduce emissions of hydrocarbons, GO, and NO are now part of every automobile s exhaust system. 

A recent study of hydrocarbon emissions in the Atlanta area revealed that plants are by far the largest emitters of hydrocarbons, with plant-derived isoprene accounting for almost 60% of the total. 

Most western countries have legislated reductions of hydrocarbon emissions. In SX plants, this means a tendency away from the use of aromatic components. In Africa, Australia, and South America, diluents containing 20 to 25% aromatic contents are still common, while in North America, diluents seldom contain more than 5% aromatics. Some processes, however, require 100% aromatic diluents because of their solvation properties. The uranium and precious metals industries often employ aromatic diluents, while cobalt, nickel, and zinc systems can anploy 100% aliphatic diluents. 

Cement plants in the United States are now carehiUy monitored for compliance with Environmental Protection Agency (EPA) standards for emissions of particulates, SO, NO, and hydrocarbons. AH plants incorporate particulate collection devices such as baghouses and electrostatic precipitators (see Air POLLUTION CONTROL methods). The particulates removed from stack emissions are called cement kiln dust (CKD). It has been shown that CKD is characterized by low concentrations of metals which leach from the CKD at levels far below regulatory limits (63,64). Environmental issues continue to be of concern as the use of waste fuel in cement kilns becomes more widespread. 

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