Painting booth

High, solvent vapors Light Piston flow, vettical from above Paint booth... 

FIGURE 8.23 Piston airflow from a filter mat ceiling In a spray painting booth. 

Piston flow is utilized in several cases where heavily contaminated air needs to be removed, for instance in a spray painting booth (Fig. 8.23). 

In practice, piston flow is not very easy to establish. A common way, utilized in cleaiiroonis and paint booths, is to have a filter mat placed all across... 

Booths are often used for work prtKedures with momentum-driven emissions. In such cases the capture devices must be placed to rake advantage of this momentum. For example, a spray paint booth would have the exhaust location downstream of the painting location, most likely at the back of the booth. The capture devices in the back wall should be suitable to reduce the momenriim of the emitted particles in such a way that they are not reflected back into the work area. Floor exhaust should be able to keep the heavier particles dowm so that they cannot be a source for secondary emissions. 

A modified form of enclosure exists in a paint booth where water is used as the physical barrier. In addition, however, the booth should be curtained off. 

Sealing A major part of the cleaning solvent is used with a cloth to clean the cars after paint spraying. The solvent is completely evaporated and cannot be recovered since sealing takes place outside the paint booth. 

A schematic of a rotary concentrator is shown in Fig. 9. The wheel rotates slowly (1-3 rotations per hour) with about 90% of its face exposed to the incoming air stream. The remainder of the face is in a regeneration sector where a counterflow of hot air desorbs the VOCs for subsequent incineration. The rotary adsorber increases the VOC concentration by a factor of 100, so there is little need for supplemental fuel in the small oxidizer that can be used to destroy the VOCs. This technology has been used for the removal of styrene emissions in the plastics molding industry. The process is also used with automotive paint booths where modular rotary concentrators and a regenerative thermal oxidizer are used to capture and destroy VOCs. 

Volatile Organic Compound and Particulate Emission Studies at AF Paint Booth Facilities Phase I... 

Stoddard solvent, used in industrial paints for dump trucks, was present in the paint booth at concentrations between 7.0 and 12.0 ppm (41.2-70.7 mg/m as determined by personal sampling apparatus however, this was considerably below the threshold limit value (time-weighted average) of 100 ppm for occupational safety (Bradley and Bodsworth 1983). 

Bradley A, Bodsworth PL. 1983. Environmental control of a large paint booth. Ann Occup Hyg 27 223-224. 

Product development in water-based paints must consider how paint residues are to be recycled in the user s painting facilities. In certain paint systems, such as auto body paint booths, overspray is caught in circulating aqueous liquors and reconcentrated by ultrafiltration (see Fig. 123). Concentrate solutions are added to the appropriate paint formulations. In a special stove-drying paint system, the material recycling rate is ca. 95%. The special membranes needed for the ultrafiltration step were developed by Hoechst subsidiaries Herberts and Hoechst Celanese Corporation, together with plant construction specialists. 

Automobile, Steel structure manufacturing Painting booth Toluene, xylene, esters, alcohols... 

The second field test assessed PCO to treat paint solvent vapors. Painting operations for military and civilian vehicles are conducted in ventilated enclosures called paint booths. Filters in the exhaust ducts trap paint droplets from the paint overspray while the VOC-laden air is typically exhausted through roof vents. The vent emissions can contain several hundred parts per million (ppm) of the paint solvents, which continue to evaporate from the vehicle after painting is complete. Most types of paint generally contain significant amounts of VOCs such as toluene, a suspected carcinogen, as well as other hazardous solvents such as methyl efliyl ketone, methyl isobutyl ketone, hexanes, xylenes, n-butyl acetate, and other components in lesser amounts. 

For the paint solvent application, a slipstream of a paint booth vent located at Fort Carson was analyzed to determine the components present with rapid scan gas chromatograph. On any operational day, several paint types are sprayed. The solvent emissions content thus varies during painting operations. In general, the amounts and types of solvent emissions from the Fort Carson paint booth are listed in Table 22.4.2. 

When the reaetor reached an operating temperature of 170°C, complete VOC destruction was achieved for the entire run except for a period of peak VOC emissions beginning at 9 30 and ending at 9 45. Thus, during this four hour period, the PCO process destroyed virtually all of the VOCs in the slip stream from the paint booth exhaust. The total time averaged conversion is estimated to be greater than 95%. These data were used to design the solar-driven, photothermal reactor system. 

Mueller, J. H., (1988), Spray Paint Booth VOC Control with a Regenerative Thermal Oxidizer , Proceed-ings-APCA Annual Meeting 81st(5), Paper 88/84.3,16 pp. 

The photothermal reactor was tested in July, 1997 for three weeks on paint booth emissions using natural sunlight. A representative data set for July 22, 1997 is shown in Figure 22.4.9 in which the total VOC concentration for the inlet and the outlet of the parabolic trough, photothermal reactor is plotted against illumination time. The solvent stream, which varied with time, generally contained about 140 ppmv of toluene, methyl ethyl ketone, methyl isobutyl ketone, xylenes, butyl acetate and ethyl benzene. The oper-... 

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