Emission VOC

In practice, pyro-gas will always contain some non-condensed light oils. Table 8-5 gives the composition of the light oil condensed from pyro-gas at 0 C (32 F).4 Listed among the components are toluene, benzene, hexane, styrene, and xylene. Emissions of benzene, ethylbenzene, toluene, and xylene were measured in the stack test at Conrad Industries. Flow rates for the tests measuring these compounds were not reported thus, emission rates (lbs/MMBtu) could not be estimated. 

No references to fugitive emissions from the pyrolysis process could be found in the literature. To estimate the order-of-magnitude emissions from this process, a model plant was assumed. Based on a Department of Energy study, 

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Petroleum refinery wastewater system VOC emissions (Subpart QQQ)... 

VOC Emissions Reduction Approach. The Rule 66-type approach focuses on solvent composition further developments have led to regulatory approaches that emphasize overall VOC emission reduction. Even though the more reactive solvents react near their emission point, all VOC compounds eventually react to form ozone pollution. This may occur some distance downwind, increasing ozone levels in areas which have low artificial emissions. 

VOC Emissions Reduction/Ozone Attainment. Tide I of the 1990 Amendments continues the process of diminishing VOC emissions from all sources to reduce o2one concentrations. A compliance timetable by category has been estabUshed, which depends on the level of current o2one concentration. The definition of a major source also depends on the o2one nonattainment category ... 

In addition to achieving the o2one standard by the deadline, moderate and higher areas must demonstrate a total net VOC emissions reduction below the base year ia accordance with an aggressive schedule of percentage reductions. These reductions are 15% ia the first six years (through November 15, 1996), and 3%/yr thereafter. 

Formulator s Dilemma. The regulatory discussion included a listing of solvents designated as HAP compounds. Emissions of these solvents are to be significantly reduced. For many appHcations this means that less is to be allowed. In a situation where the allowed VOC emission levels are also being reduced, the formulator would like to use the most effective solvents available. In the past, MEK and MIBK were frequently used as active solvents and aromatic hydrocarbons as diluents. These solvents have been popular because they are cost-effective. 

Reformulating to reduce HAP solvents frequently means that solvent blend costs increase. The newer blends are generally not be as effective. For example, many coatings were usually formulated using ketones as the active solvents with aromatic hydrocarbons as diluents. This combination produced the most cost-effective formulations. However, when MEK, MIBK, toluene, and xylene became HAP compounds, less-effective solvents had to be used for reformulation. Esters are the most common ketone replacements, and aUphatic diluents would replace the aromatic hydrocarbons. In this situation, more strong solvent is required compared to the ketone/aromatic formulation and costs increase. The combination of reduced VOC emissions and composition constraints in the form of HAP restrictions have compHcated the formulator s task. 

Supercritical Atomization. Atomization can be obtained by mixing a supercritical fluid (SCF) with the material to be atomized. This process reduces volatile organic compound (VOC) emissions as the SCF acts as a solvent and replaces some of the hydrocarbon solvents in the material (see... 

Gloss Enamels. In contrast to exterior and flat wall paint, about half of the gloss paint or enamels sold are based on alkyd resins. Professional painters particularly favor the continued use of alkyd gloss paints. The need for reduction of VOC emission levels, especially in California, has led to efforts to increase the soflds content of alkyd paints or overcome the disadvantages of latex gloss paints. 

Uses that have developed for uv curing reflect the special advantages of the system rather than replacement to reduce VOC emissions or energy... 

Conventional nitrocellulose lacquer finishing leads to the emission of large quantities of solvents into the atmosphere. An ingeneous approach to reducing VOC emissions is the use of supercritical carbon dioxide as a component of the solvent mixture (172). The critical temperature and pressure of CO2 are 31.3°C and 7.4 MPa (72.9 atm), respectively. Below that temperature and above that pressure, CO2 is a supercritical fluid. It has been found that under these conditions, the solvency properties of CO2 ate similar to aromatic hydrocarbons (see Supercritical fluids). The coating is shipped in a concentrated form, then metered with supercritical CO2 into a proportioning airless spray gun system in such a ratio as to reduce the viscosity to the level needed for proper atomization. VOC emission reductions of 50% or more are projected. 

AcryHc lacquers also have disadvantages the gloss of the air-dry film is too low and the surface must be mbbed to achieve the high gloss necessary for automotive top coats and most importantly, VOC emissions are very high. AcryHc lacquers are expected to be phased out when controls become more restrictive. 

Pilot Studies. AppHcations requiring the reduction of VOC emissions have increased dramatically. On-site pilot tests are beneficial in providing useful information regarding VOC emission reduction appHcations. Information that can be obtained includes optimum catalyst operating conditions, the presence of contaminants in the gas stream, and the effects of these contaminants (see Pilotplants and microplants). 

Selective Catalytic Reduction of Nitrogen Oxides The traditional approach to reducing ambient ozone concentrations has been to reduce VOC emissions, an ozone precurssor. In many areas, it has now been recognized that ehmination of persistent exceedances of the National Ambient Air Qnality Standard for ozone may reqnire more attention to reductions in the other ingredients in ozone formation, nitrogen oxides (NOJ. In such areas, ozone concentrations are controlled by NO rather than VOC emissions. 

D. Simpson, Biogenic VOC Emissions in Europe Modelling the Implications for Ozone Control... 

VOC emissions must be reduced by at least 15% from 1990 levels in ozone nonattainment areas. 

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