Rinse zone

Environmental Protection. On account of the high paint transfer efficiency and low solvent content, environmental pollution in electrodeposition coating is much lower than with spray coating. The solvent contents of electrodeposition paints relative to the solids content are 5-10% in comparison with solventborne spray paints with a solvent content of 50-100%. The most important sources of emission are the electrodeposition tank, the rinsing zone, the stoving oven, and the drain of the ultrafiltrate [3.125]. Developments in new electrodeposition paints aim to reduce the organic volatile solvent content, to have fewer condensation products in the stoving ovens, and to have lead-free formulations [3.126]. 

The fresh water for the bottle rinsing and cooling is another miaobiological risk point. Microbiological control of the fresh water is essential to avoid any re-contamination of the bottle after cleaning. Disinfection with, for example, chlorine dioxide or peracetic acid is used to reduce the risk of microbiological infection in the rinsing zones. 

The height of the vapor rinse zone is generaiiy chosen to be a minimum vaiue, suitabie to comfortabiy contain the parts basket, and iittie higher. After aii, an increase of this height reduces the freeboard height for the same overaii unit height. 

The figure above shows the calculated effect of freeboard upon emission control after the cooling coil using CTW has produced its effect. That effect was to reduce perchloroethylene concentration from 1,000,000 ppm (pure solvent in the vapor rinse zone) to 25,000 to 50,000 ppm depending upon the assumed temperature of the CTW The effect of freeboard is to reduce the perchloroethylene concentration from those levels to a few hundred ppm The latter level of emission is easily diluted with only a modest level of room ventilation to produce concentrations of perchloroethylene in the work area well below the exposure limit (25 ppm per ACGIFI and 100 ppm per OSHA)... 

Transfer the somewhat-cooled wet porous electrodes to another physically isolated cleaning chamber °, at a location adjacent to the primary cooling coils in the chamber (called the vapor rinse zone in Figure 3.33). Flush the electrodes with RA cosolvent vapor which easily condenses to liquid in the primary cooling coils. The SA cosolvent and RA cosolvents are adequately miscible, the exceptionally low surface tension of the RA cosolvent will aid in flushing the porous stmcture of these electrodes. 

The floe or rinse zone is a chamber in the conveyor hub behind the feed zone, sometimes separated by a buffer chamber to minimise cross contamination. The required throughput of this chamber is an order of magnitude less than that of the feed zone. Therefore, it does not require the same sophistication as the feed zone, nor does it require erosion protection. 

The variations of floe and rinse zones are mainly associated with size and how the rinse or flocculant discharges into the main process stream. Simple accelerators on the chamber wall are sometimes fitted. The more efficient floe chambers will discharge the flocculant evenly adjacent to the feed discharge into the pond. 

As a rinse zone, discharge is at a different point from flocculant, often at the junction between the wet and the dry beach or spread over a finite length of wet and/or dry beach. Special spray nozzles are often used to spread and direct the spray, to improve rinse efficiency. 

The central supporting tube of the conveyor, which houses the feed and iloccularit or rinse zones, and the conveyor bearing assemblies The rotational reaction of the conveyor to the resistance oft ake movement, expressed in terms of force t imes radius at which the force is acting... 

Actually this dilution phenomenon is partially avoidable in three-zone SMB separation processes when a simulated countercurrent is employed instead of a true countercurrent when port motion occurs, a fully rinsed column (thus full of eluent) is added to the end of zone 3. As a matter of fact, during a first part of the switching period, pure eluent will exit from the raffinate outlet. Of course, this can be discarded or recycled to the eluent tank. During the... 

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