# US 4,396,405 A · Paint spray booth emissions control process

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- Number: US 4,396,405 A
- Document ID: US4396405A
- Status: Granted
- Kind: A
- Application number: 06/305,882
- Filed: 1981-09-28
- Granted: 1983-08-02
- Earliest claimed: 1981-09-28
- Assignees: Nalco Chemical Company
- Inventors: William H. Lindenberger; Theodore P. Sieder; Edwin C. Zuerner, Jr.
- Web page: https://patentgrep.com/patent/US4396405A

## CPC

- B01D 47/00: Separating dispersed particles from gases, air or vapours by liquid as separating agent (B01D45/10 takes precedence; fractionating columns or parts thereof B01D3/16)
- B05B 14/49: specially adapted for solvents
- Y02P 70/10: Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D)
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method for continuously removing volatile organic solvent paint carriers from the atmosphere of paint spray booths is disclosed. By the process described, an oil-water emulsion is used to scrub volatile organic materials from the paint spray booth atmosphere. The emulsion is then broken and the oil phase is distilled to recover volatile components. The non-volatile components of the oil phase and recovered water are then recombined to form an emulsion and recycled to the paint spray booth.

## Claims

### Claim 1

A method for the continuous removal of volatile organic paint solvents from an oil-in-water emulsion used as the wash water in a paint spray booth which comprises the steps of:
(a) forming an oil-in-water emulsion of water and a high boiling organic liquid in which the volatile organic paint solvent is soluble at a pH of 7.5-12,
(b) contacting the oil-in-water emulsion of step (a) with solvent laden air from the paint spray booth;
(c) continuously withdrawing at least a portion of the emulsion from a sump after it has contacted the paint solvent and oversprayed paint laden air in the paint spray booth;
(d) separating by chemical means at a pH of 3.0-6.5 the portion of emulsion withdrawn from the paint spray booth sump to recover a solvent-rich, high-boiling organic liquid phase containing the paint solvent and a water phase;
(e) distilling the paint solvent from the high boiling organic liquid to recover the volatile organic paint solvent and a high boiling organic liquid;
(f) combining the water phase of step (d) with the recovered high boiling organic liquid of step (e) and chemically reforming an oil-in-water emulsion; and then,
(g) repeating steps (b) to (f) above.

### Claim 2 (depends on 1)

The method of claim 1 wherein subsequent to contacting the oil-in-water emulsion with the solvent and oversprayed paint in the paint laden air spray booth and prior to separating said emulsion into a solvent-rich high-boiling organic liquid phase and a water phase, the paint solids are separated from the emulsion.