Volatile organic compounds (VOC) are the major contaminants emanated from metal coil surface coating operations. Specific operations that emit VOC are the coating application station, the curing oven and the quench area. The amount of VOC emissions from individual coil coating lines varies widely from one installation to another. There are many vital reasons that influence the emission rate such as VOC content of coatings as applied, VOC density, area of metal coated, solids content of coatings as applied, thickness of the applied coating and number of coats applied. Due to the evaporation of organic solvents contained in coating, the VOC compounds are emitted. Coil coating operations mostly use solvent-based liquid paints. Solvents are driven off during dying and curing operations. The proportion of overall VOC emitted at each emission point varies from one installation to another, but, on the average, about 8 percent is given off at the coating application station, 90 percent the oven and 2 percent the quench area. The huge majority of coil coating operations use solvent-based liquid paints. During the drying and curing operation, the solvents are driven off. The emission of VOCs can be influential in producing smog formation and other detrimental effects and is regulated for by the EU and other individual national authorities.
The values taken therein the table represents maximum, minimum, and average emissions from small, medium, and large coil coating lines. An average film thickness and an average solvent content are expected to figure up the average emission factor. Waterborne coatings are the sole low-VOC-content coating technology that is used to a substantial amount in the coil coating industry. These coatings have considerably lesser VOC emissions than most of the organic solventborne coatings. Additionally, In order to control these emissions, new methodologies are available in the market. One such methodology is the usage of oxidizers which collect emitted solvents where heat is recovered to assist in curing operation. Oxidizers used in coil coating market have high efficiency in removing VOCs and oxidizers to collect and incinerate emitted solvents. The usage of oxidizers requires huge investment and they are not applicable for smaller installations. Even though most of the plants operate within the limits of government regulation for VOC emission, there are many factors which can affect the throughput. The factors that are responsible for throughput are product mix, line speed and capacity and oven management regimes.