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EP0025066A1 - Procede de revetement d'une piece a usiner. - Google Patents

Procede de revetement d'une piece a usiner.

Info

Publication number
EP0025066A1
EP0025066A1 EP80900752A EP80900752A EP0025066A1 EP 0025066 A1 EP0025066 A1 EP 0025066A1 EP 80900752 A EP80900752 A EP 80900752A EP 80900752 A EP80900752 A EP 80900752A EP 0025066 A1 EP0025066 A1 EP 0025066A1
Authority
EP
European Patent Office
Prior art keywords
water
coating
accordance
coating composition
volatile organic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP80900752A
Other languages
German (de)
English (en)
Other versions
EP0025066B1 (fr
EP0025066A4 (fr
Inventor
Dennis Schuetzle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ford Motor Co
Original Assignee
Ford Motor Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ford Motor Co filed Critical Ford Motor Co
Publication of EP0025066A1 publication Critical patent/EP0025066A1/fr
Publication of EP0025066A4 publication Critical patent/EP0025066A4/fr
Application granted granted Critical
Publication of EP0025066B1 publication Critical patent/EP0025066B1/fr
Expired legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B14/00—Arrangements for collecting, re-using or eliminating excess spraying material
    • B05B14/40—Arrangements for collecting, re-using or eliminating excess spraying material for use in spray booths
    • B05B14/46—Arrangements for collecting, re-using or eliminating excess spraying material for use in spray booths by washing the air charged with excess material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B14/00—Arrangements for collecting, re-using or eliminating excess spraying material
    • B05B14/40—Arrangements for collecting, re-using or eliminating excess spraying material for use in spray booths
    • B05B14/46—Arrangements for collecting, re-using or eliminating excess spraying material for use in spray booths by washing the air charged with excess material
    • B05B14/465—Arrangements for collecting, re-using or eliminating excess spraying material for use in spray booths by washing the air charged with excess material using substantially vertical liquid curtains or wetted walls behind the object to be sprayed

Definitions

  • This invention relates to a process of coating a workpiece in a spraybooth using a sprayable coating composition; the sprayable coating composition comprises volatile organic compound; the spraybooth communicates with a water wash.
  • the invention relates to contact in the water wash between scrubbing water of a conventional high volume, low energy, wet scrubber and airborne components of the sprayable coating composition that exit the spraybooth through the water wash.
  • volatile organic compound(s) refers to a compound (s) in a coating composition, (normally as part of its liquid carrier) which is emitted as vapor or otherwise during industrial coating operations.
  • This invention relates to a process of coating using a sprayable coating composition in a spraybooth that communicates with a water wash, the water wash permitting contact between airborne components of the sprayable coating composition that enters the water wash and scrubbing water of a high volume, low energy wet scrubber operating at an inlet and outlet pressure difference of less than about 10 inches of water.
  • this invention relates to an improvement in the coating process which comprises (A) spraying in the spraybooth a scrubable coating composition comprising a volatile organic compound that boils above about 98°C at atmospheric pressure, is water soluble above about 0.6% by weight at 20°C and is transitory in the scrubbing water; (B) capturing in the scrubbing water a volatile portion of said scrubbable coating composition wherein the volatile portion comprises an amount of the volatile organic compound and wherein an ingredient of the scrubbing water reacts with a portion of the amount; and (C) maintaining a concentration of the volatile organic compound and reaction products of the volatile organic compound in the scrubbing water below that at which efficiency falls below about 10% (preferably higher, e.g. at least 30%) of a maximum efficiency.
  • the scrubbing water comprises base; also, preferably, the reaction between the volatile organic compound and the ingredient is a hydrolysis reaction,
  • a preferred embodiment comprises (a) spraying in the spraybooth a scrubbable coating composition comprising a volatile organic compound that boils above about 120oC at atmospheric pressure, is water soluble above 0.6% by weight, preferably above about 6% by weight at 20oC and is hydrolyzable; (b) capturing in the scrubbing water a portion of the scrubbable coating composition wherein the portion comprises an amount of the volatile organic compound and the scrubbing water has a ph that enhances hydrolysis; and (c) maintaining a concentration of the volatile organic compound and hydrolysis products of the volatile organic compound in the scrubbing water below that at which efficiency falls below about 10% of a maximum efficiency.
  • the pH is preferably basic, desirably above about 9 and more preferably between about 9.5 and 11.5.
  • the amount captured may be up to about 90% or more by weight of the weight of the volatile organic compound of aforementioned characteristics sprayed in the spraybooth.
  • Spraying may be electrostatically or otherwise; electrostatic has the advantage of higher transfer efficiency than conventional application that further results in reduced emissions from the process of coating in accordance with the invention.
  • this invention comprises (a) spraying in the spraybooth a scrubbable coating composition comprising a volatile organic compound that boils above about 98oC at atmospheric pressure and is soluble above about 6% by weight at 20oC and a hydrolyzable volatile organic compound that boils above about 98oC and is water soluble above about 0.6% by weight at 20oC; (b) capturing in the scrubbing water a volatile portion of the scrubbable coating composition wherein the portion comprises an amount of the compound and the scrubbing water has a pH that enhancss hydrolysis of the hydrolyzable scrubbable compound; and (c) maintaining a concentration of the volatile organic compounds and any hydrolysis product thereof below that at which efficiency falls below about 10% of a maximum efficiency.
  • this invention comprises biologically, physicochemical or biologically and physicochemically removing one or more products of the preferred hydrolysis reaction so as to maintain a concentration of the volatile organic compound and any hydrolysis products thereof in the scrubbing water below chat at which efficiency falls below about 10% of a maximum efficiency.
  • Capture by the scrubbing water of a volatile organic compound of the aforementioned characteristics may or may not result in a lasting increase in the amount of the volatile organic compound in the scrubbing water. Since it is, however, transitory in the scrubbing water, then it does not, of course, accumulate as rapidly in the scrubbing water as comparable volatile organic compounds that are not transitory; it also, therefore, does not retard as readily capture of further amounts of it by the scrubbing water.
  • paint spraybooths may operate, in accordance with this invention, in a manner that transfers volatile emissions therefrom into water. Physicochemical, biological or physicochemical and biological process may then treat and remove volatile organic compounds and their products from the water.
  • This invention accordingly further includes maintaining uptake by the scrubbing water of volatile organic compound of the aforementioned characteristics.
  • the uptake by the scrubbing water is maintained when the amount of volatile organic compound or product therefrom does not exceed certain levels, i.e., below about 50 grams/liter in one embodiment.
  • Figure 1 illustrates in schematic form one type of paint spraybooth with associated (in this case integral) water back sections that may be operated in accordance with this invention.
  • Associated hardware such as pumps, valves, filters, scrubbing devices, et. have been omitted for simplicity and greater clarity.
  • FIG. 2 illustrates a pilot scale spraybooth with integral water wash back section. This pilot scale spraybooth was used in Pilot Trials I, II, and III in the examples,
  • FIG 3 is a schematic of the total hydrocarbon content (THC) and gas chromatography (GC) sampling systems of the Pilot Spraybooth of Figure 2.
  • Figure 4 is a schematic of east water pit system, air sampling lines and analyzers monitored in the assembly plant (AP) trial of the examples.
  • Figures 5, 6 and 7 are graphs showing solvent uptake in scrubbing water in Pilot Trials I, II and III respectively.
  • Figures 8 and 9 are graphs showing uptake by scrubbing water during the AP trial using 119B and 120C coating compositions, respectively.
  • Figure 10 is a graph showing the effects of scrubbing during the AP trial using coating composition 120C.
  • Figure 11 shows schematically the AP stock sampling port and flow measurement port locations.
  • Figure 12 shows the AP prime spraybooth stack sampling system.
  • Figure 13 shows the AP stack sample manifold flow regulation system.
  • Figure 14 shows the AP east main enamel spraybooth stack sampling system.
  • DETAILED DESCRIPTION OF THE INVENTION Scrubbable compound shall refer to a volatile organic compound which (1) boils above about 98oC at atmospheric pressure and (2) is (are) water soluble above about 0.6% by weight at 20°C.
  • Transitory scrubbable compound shall refer to a scrubbable compound that reacts with an ingredient in the scrubbing water preferably at a rate at least about 5% of its rate of uptake by the scrubbing water.
  • An example of such ingredient is a base.
  • Another example is acid.
  • Still another ing.edient is potassium permanganate. Reactions include hydrolysis, oxidation, chelation, etc.
  • Figure 1 shows schematically one type of spraybooth with associated water wash.
  • Workpieces e.g. autobodies, as in Figure 1, enter and exit the spraybooth along a line perpendicular to the spray of a sprayable coating composition and along a grate opening to the water wash.
  • Relatively clean air enters the booth downwardly and perpendicular to the workpieces and grate.
  • the relatively clean air draws subsisting airborne components of the coating composition through the grate into the water wash.
  • the water wash comprises a wet scrubber that takes particulate, and in the case of this invention, an amount of volatile organic compound from the air.
  • the air enters the water wash at a rate of between about 250-3000 cubic feet per minute per linear foot (cfm/ft) of the booth, and mote usually between about 500-1500 cfm/ft.
  • This invention particularly concerns use of high volume, low energy wet scrubbers that operate at inlet and outlet pressure differences below about 10 inches of water and even as low as below 6 inches of water, e.g. about 1-5 inches of water pressure difference.
  • the pressure drop may be determined by pressure measurements at convenient locations
  • measurements may be made at locations of just before first water contact and just after last water contact in the water wash; the difference of these measurements is a measurement of the pressure difference.
  • Another way to characterize conventional spraybooth wet scrubbers is by what is referred to as amount of particulate that emits after wet scrubbing. "Grain” refers to the amount of particulate per unit volume of air, e.g., 1 grain equals 0.0648 g/scfm.
  • Water flow in the water wash may vary. Normally, it will be between about 5-100 gallons per minute per linear foot of the spraybooth. Countercurrent air and water flows in the water wash are preferred in accordance with the invention; water washes with concurrent air and water flows should, however, also be suitable.
  • the sprayable coating composition is selected to be a scrubbable coating composition.
  • a scrubbable coating composition comprises a transitory scrubbable compound.
  • Preferred scrubbable compounds comprise oxygenated compounds. More preferred scrubbable compounds are selected from the group consisting of esters, ethers and alcohols. Examples of the esters are mono and di esters such as acetates, adipates, glutarates, succinates and the like. More specifically, examples are cellosolve acetate (i.e. ethylene glycol monoethyl ether acetate), methyl cellosolve acetate (i.e. ethylene glycol monomethyl ether acetate), butyl cellosolve acetate (i..e. ethylene glycol monobutyl ether acetate), butyl acetate ethyl carbitol acetate (i.e.
  • diethylene glycol monoethyl ether acetate diethylene glycol monoethyl ether acetate
  • butyl carbitol acetate i.e. diethylene glycol monobutyl ether acetate
  • the alcohols are amino alcohols such as alkanol amines, ester alcohols, and ether alcohols. More specific examples of alcohols are triethanol amine, butyl carbitol
  • WiPO i.e. diethylene glycol monobutyl ether
  • cellosolve i.e. ethylene glycol monoethyl ether
  • methyl cellosolve i.e. ethylene glycol monorcethyl ether
  • butanol ethylene glycol
  • a preferred transitory scrubbable compound is an ester and especially an ether ially linked ester such as cellosolve acetate.
  • a preferred transitory compound also preferably boils above about 120°C.
  • scrubbable, as well as transitory scrubbable compounds, alone or together are suitable for use in aqueous and non-aqueous coating compositons at desired levels.
  • a desired level is as high a percentage as possible of the volatile organic compound in the coating composition, taking into account other factors in coating composition formulation.
  • aqueous and non-aqueous coating comnositions are those including thermoplastics, and/cr theromosets which, in turn, may be topcoats, sealers, primers. etc.
  • the process of this invention further includes capture of transitory scrubbable compounds by the scrubbing water in the water wash.
  • Sprubbing water as used herein means water in the water wash and any additives therein that com ⁇ s into scrubbable contact with airborne components of a sprayable coating composition. This contact is, for example, between water of a venturi spray or water curtain or other high volume, low energy scrubber air water interface and the airborne components.
  • scrubbing water typically contains water treatment compounds.
  • the process of this invention has not been found to detract from function or employment of typical water treatment compounds.
  • water treatment compounds that act to "kill" paint overspray. It includes water treatment compounds that may act to detachify, coagulate, precipatate, float or otherwise treat paint overspray. It still even further includes water treatment compounds that are surfactants, anti corrosion agents, bacteriocides, fungicides, etc. Examples of water treatment compound formulations include those in U.S. Patents 3,985,922; 4,002,490; 4,090,001; 4,125,476; 4,130,674 and Canadian Patent 589,360.
  • Especially preferred water treatment compound formulations include amines, aluminates, silicates and the like at a variety of basic pH levels. Modifiers of pH may be added on a continous basis to circulating scrubbing water.
  • Examples of commercially available water treatment compounds are those of Nalco 8724 containing polyelectrolyte; Nalco 8723 containing polyelectrolyte; Nalco 2 containing sodium aluminate, and Nalco 8735.
  • water treatment compounds may be removed along with treated overspray by conventional means.
  • the process of this invention preferably includes such a removal and an addition of make up water treatment compounds.
  • the scrubbing water has a concentration of a transitory scrubbable compound and products therefrom below that at which efficiency falls below about 10% of a maximum efficiency. Normally, such is an amount below 50 grams/liter of scrubbable compound, e.g., between about 0.1-20 grams/liter. Maximum efficiency, however, is when the scrubbing water is essentially free of the transitory scrubbable compound and any product therefrom.
  • Preferred scrubbable coating compositions comprise a hydrolyzable scrubbable compound that boils above about 120oC. Uptake by the scrubbing water of such preferred hydrolyzable scrubbable compound continues with desirable efficiency even when the scrubbing water contains higher levels of hydrolyzable scrubbable compounds and products therefrom within the above ranges.
  • Removal of transitory scrubbable compounds (are any products therefrom) from scrubbing water may be by biological, physicochemical or biological and physicochemical processes; alternatively, the scrubbing water may be simply replaced with fresh (e.g., municipal) water.
  • physicocheraical processes include coagulation, precipitation, filtration, absorption, ion exchange, membrane separation, and chemical oxidation.
  • the sprayable coating composition is selected to be a scrubbable coating composition, i.e., comprise a transitory scrubbable compound.
  • a scrubbable coating composition i.e., comprise a transitory scrubbable compound.
  • the pressure drop of the water wash affects efficiency. Higher pressure drops cause more efficient capture of transitory scrubbable compounds. Further, lower levels of transitory scrubbable compounds in the scrubbing water allows higher efficiencies.
  • the scrubbing water generally retains higher boiling scrubbable compounds longer than lower boiling scrubbable compounds, assuming equal solubilities. Similarly, the scrubbing water generally retains more water soluble transitory scrubbable compounds longer than less water soluble transitory scrubbable compounds, assuming equal boiling points. Furthermore, the pH, for example, can affect efficiency at which the scrubbing water takes up hydrolyzable compound.
  • the amount of emissions abated in accordance with this invention may be generally added to the amount of abatement achieved by these other factors.
  • these other factors include (1) solids content of the coating composition, (2) transfer efficiency of spray application, e.g., mode of spraying and (3) manner of handling emissions from bake ovens, e.g., incineration by catalyst.
  • Table 2 shows solvent composition and physical properties of sprayable coating compositions used in the three trials.
  • Trial 1 examined high solids enampl 3760;
  • Trial 2 examined non-aqueous dispersion enamel 5180;
  • Trial 3 examined high solids enamel 3742.
  • a Binks Model 61 automatic spraygun equipped with a 63C fluid nozzle and 53PR air cap sprayed paint at a rate in each trial of 0.002 gallons of solids per minute per linear foot of back section.
  • the spraygun actuated automatically on a 15 second cycle, operated with open gun times ranging between 2 and 4 seconds in each cycle.
  • the spraygun nozzle was diagonally five feet from the air inlet of the back section.
  • the spray from the nozzle was in a vertical fan shape and at approximately -45° from
  • a Beckman Model 402 Total Hydrocarbon (THC) Analyzer continuously monitored stack emissions .
  • An Omniscr ibe Model B5217-5 two-channel recorder simultaneously displayed instantaneous and electronically integrated (over ten , 15 second spray per iods) output from the analyzer .
  • the THC analyzer was zeroed with Ultra Zero Air (Air Monitor ing , Inc . ) and spanned with 80 and 204 ppm propane-in-air standards ( ⁇ 1% accuracy, Accublend , Scott Research Company) approximately every five hours .
  • Samples of stack emissions passed anisokinetically through a twelve foot stainless steel line to the analyzer during the first trial . Heat tracing occurred over all but a two-foot , in-stack section of this sample line . In the other trials, the system shown in Figure 3 isokinetically sampled stack emissions .
  • GC analyses determined emission rates of specif ic solvents .
  • Dupont Model 4000 constant flow, personnel sampl ing pumps collected known volumes of air emissions directly from the spraybooth exhaust stack onto traps containing Tenax GC polymer. Selection of sampling times averaged rapid temporal changes in stack emission levels.
  • the inlet of a Hewlett Packard Model 5711A Gas Chromatograph equipped with a flame ionization detector (FID) received heat desorbed samples from the traps.
  • FID flame ionization detector
  • Packard 3385A integration system reduced the 5711A data in ail trials.
  • a Perkin Elmer Sigma 1 GC system equipped with a flame ionization detector (FID) measured uptake of specific solvents into the spraybooth water. Collection of booth water grab samples occurred every ninety minutes in 25 ml. headspace-free vials fitted with teflon lined caps. After centifugation to remove suspended solids, there was direct aqueous injection into the Sigma GC.
  • FID flame ionization detector
  • Airtight containers stored frozen grab samples of floating and sunken sludge.
  • a Hewlett Packard 5992B GC-MS system provided qualitative confirmation of solvent identity of spraybooth water, sludge and air emissions. Sampling techniques were identical to those in GC analysis.
  • Spraybooth exhaust flow measurements were in accordance with Ford Manufacturing Standards BAX-2 procedures.
  • Figures 5, 6 and 7 illustrate an increase in the amount of solvent compounds in booth water as a function of paint spraying time for pilot trials I, II and III, respectively.
  • Non-polar compounds like xylene and esposol 260 did not appear appreciably in the booth water.
  • Figures 5, 6 and 7 express cellosolve acetate by combining cellosolve acetate and its hydrolysis product cellosolve.
  • Air Emissions Tables 8, 9 and 10 show solvent concentration (corrected to 760 mm Hg , 20 oC) at selected times during each of the three pilot trials. In these t ⁇ bles, the weight per unit volume solvent concentrations are also recalculated as their equivalent total hydrocarbon concentration in terms of propane. These totals are compared to actual THC concentrations measured by the 3eckman 402 Analyzer. The calculations used carbon number response factors derived from the literature or from empirical results.
  • Tables 14, 15 and 16 present material balances for several sampling periods during Pilot Trials I, II and III, respectively. For each sampling period, solvent spray rate versus solvent emission and capture rate is presented. The materials balances range between 81 and 102 percent.
  • An assumption for. the calculations in Tables 14, 15 and 16 is that the sludge had a composition as presented in Tables il , 12 and 13, respectively. The sludge production rate was estimated from weight solids of each original paint since all the paint solids sprayed during the pilot tr ials entered the back sec tion .
  • FIG. 4 shows schematically pertinent portions of spraybooth, water line and stack arrangement of the AP painting process.
  • electr ⁇ coated vehicle bodies passed sequentially through a Prime Spraybooth, a Prime Bake Oven, a West Main Enamel Booth, an East Main Enamel Booth, a Main Enamel 3ake Oven, and, if required, a Tutone-Repair Spray Booth and Bake Oven.
  • mod if ied Behr-Ransbury equipment electrostatically sprayed approximately 50% of a taupe primer.
  • Stacks 9 and 10 ( Figure 4) exhaust the west end.
  • the vehicles then exited the Prime Spraybooth and entered the Prime Bake Oven.
  • the Prime Spraybooth stacks for example, exhausted n-butyl acetate and butyl cellosolve even though these solvents arose from spraying in the East Main Enamel Booth.
  • the east water pit held 170,000 ⁇ 5000 gallons during the two production trials. At the beginning of each trial, the water showed essential freedom of solvent. The retention time of water in the east water pit was about 10 minutes. Metering of Nalco 8724 to the water was at a rate of about 1.5 gallons per hour. The water had a basic pH which was in a range between 10-10.5 through most of the trials. A combination of manual and constant metered additions of caustic (50%) maintained the pH. The first trial examined emission from taupe primer 119B; the trial lasted two days. The second trial examined primer 120C; it lasted four days.
  • Table 5 shows the cellosolve acetate concentration of the 119B and 120C coatings and enamels sprayed in the East Main Enamel. Booth along with the volume of each- coating sprayed daily.
  • a heat-traced manifold system provided an average sample from all 10 stacks on the Prime Spraybooth to a Beckman Model 402 THC Analyzer.
  • a second, heat-traced manifold system provided an average sample from seven of the fourteen East Main Enamel Spraybooth stacks to a Beckman 400
  • THC Analyzer Total hydrocarbon measurements made on all 14 enamel booth stacks determined that the emission rate from the seven stacks monitored during the trial was equivalent to the seven not monitored. In both of these stack systems, the fraction of the total THC analyzer flow taken from each particular stack was proportioned to each stacks contribution to the total booth exhaust flow. A second Beckman 402 THC Analyzer monitored exhaust emissions from the single stack on
  • Figure 11 illustrates sampling locations on the exhaust stacks of each system.
  • Dupont Model 4000 constant flow personnel sampling pumps collected known volumes of hydrocarbon vapor onto traps containing Tenax GC polymer.
  • Samples came from the FID bypass streams on the three THC Analyzers used to monitor the Prime Booth, Prime Bake Oven, and East Main Enamel Stack Systems. Sampling frequency, flow, time and gas chromtographic system used for analyzing samples appear in Table 6.
  • the Hewlett Package Model 5711A gas chromatograph was the same instrument used in the pilot plant trials except that a Perkin Elmer Sigma 1 Data System reduced the data.
  • a heat-traced stainless steel manifold system provided an average emission sample from the - ten prime spraybooth stacks.
  • Figure 11 illustrates sampling point on each stack.
  • 1/4" i.d. sections of line (Technical Heaters, Inc. Model 500-1/4) linked each stack to a central 3/8" i.d. trunk line (Technical Heaters,
  • IJUR between the 1/4" and 3/8" lines regulated the flow from each stack ( Figure 13 ) .
  • Closure of an in-line toggle valve to bypass the flow through a Matheson Model 603 rotamet ⁇ r accomplished flow monitoring .
  • the same rotameter equipped with Swagelok Quick-Connect Connectors , permitted balance of the flow from each stack on the system. Sample flow from each stack was between 0.5 and 1.0 1/min.
  • a Metal Bellows Model 302HT pump provided sample flow.
  • An Associated Testing Laboratories, The Model BP-1102 oven maintained pump temperature at 285oF to prevent sample condensation .
  • the effluent from the pump was split .
  • Approximately 1.9 1/min . of flow went to the THC analyzer and the remaining flow vented through a S-110 dry test, meter .
  • the Beckman 402 THC Analyzer was modif ied so that flow from the glass fiber f ilter bypassed the internal metal bellows pump and went directly to the FID capillary-splitter .
  • the THC analyzer was zeroed with Ultra Zero Air (Air Monitor ing , Inc . ) and spanned with an 80 ppm propane-in-air standard approximately every four hours . An additional two-point calibration was performed daily with 80 and 204 pom propane-in-air standards (t 1% accuracy, Scott Research Co . ) . The output from the THC analyzer was recorded directly and was also electronically integrated over periods of 10 .0 minutes . An Omniscr ibe Model B5217-5 two-pen recorder recorded both outputs continuously.
  • a heat-traced stainless manifold system provided an average emission sample GC and THC analysis from seven of the fourteen East Main Enamel Spraybooth stacks ( Figure 14 ) .
  • the sampling point on each stack is illustrated in Figure 11.
  • the heat-traced sample lines and the associated temperature and flow control equipment used on the East 'Main Enamel Booth were identical to the equipment used on the Pr ime Spraybooth ( Figure 12, 13 ) .
  • the Beckman 400 THC Analyzer was zeroed with Ultra Zero Air (Air Monitoring, Inc.) and spanned with 204 ppm propane-in-air standard approximately every four hours ( ⁇ 1% accuracy, Scott Research Co.).
  • An Omniscribe Model B5118-4 strip chart recorder recorded continuously the output from the THC analyzer.
  • a Beckman 402 THC Analyzer monitored emissions from the single stack on the Prime Bake Oven. Samples of the emissions passed through an eleven foot heat- traced line supplied with the THC analyzer. The instrument was zeroed with Ultra Zero Air (Air Monitoring, Inc.) and spanned with 204 ppm propane-in-air standard ( ⁇ 1% accuracy, Scott Research Co.) approximately every four hours. A Weather Measure Model EPR-200A strip chart recorder recorded continuously the output from the THC analyzer.
  • a Perkin Elmer Sigma 1 Gas Chromatographic System measured solvents in the water of the East Pit System. Booth water grab samples occured approximately every 2.5 hours in 25 ml headspace-free vials fitted with teflon-lined caps. The GC received the samples (after centifugation to remove suspended solids) by direct aqueous injection.
  • Figures 8 and 9 illustrate uptake of specific solvents into the water of the AP East Pit-System during the 119B and the 120C taupe primer trials as a function of paint spraying time.
  • Figures 8 and 9 express results as increasing booth water concentration and as mass of solvent, captured.
  • Least squares regression analysis gave cellosolve acetate accumulation in the booth water at a rate of 4.5 ⁇ 0.3 kg/hr of spraytime during the 1198 trial and at 11.9 ⁇ 0.2 kg/hr during the 120C trial.
  • the solvent pentoxane accumulated in the booth water during both trials. It was a constituent of a cleaning/purge solvent blend and not contained in any primer or enamel solvent package.
  • Table 17 and tables 18, 19 and 20 show daily average stack emission rate for specific solvents from the Prime Spraybooth, the Prime Bake Oven, and the East Main Enamel Spraybooth during the 119B and 120C trials, respectively.
  • the tables express emission rates in terms of kilograms of solvent emitted per hour of paint spraying time (corrected to 20°C, 29.9" Hg . ) Calculations account for daily differences in stack flows (Table 4).
  • the tables express average concentration of each solvent in milligrams per cubic meter (standard conditions: 29.9" Hg, 20oC); and the total concentration is reexpressed in terms of propane (C 3 H 8 ) and compared to the daily average THC concentrations measured at each source with either a Beckman 400 or 402 Analyzer.
  • the difference between the measured and calculated THC concentrations for the Prime and Enamel Spraybooths seldom exceeded 10 percent. Fluctuations in the measured THC values through each day, however, frequently exceeded this level. Measurements in the Prime Spraybooth showed a highly variable methane background ranging from 9 to 90 ppm as C 3 H 8 .
  • a comparison between the calculated and measured THC values for the bake oven (Table 19) is inappropriate because of such a variability.
  • Table 22 compares Prime Spraybooth stack volatile organic compound emission rate to spray rate. An efficiency in the first trial can not be based on this data because the. emission rate exceeds the spray rate. An efficiency in the second trial (emitted over sprayed) is 13%. Error analysis, however, suggests the latter result neither proves nor disproves reduction of emissions because errors in the measurements involved in the material balance were i 22%.
  • Figure 10 gives an example of how backsection scrubbing abatement might be used, in part, to reduce the equivalent emissions (VOC) of a 120C solvent based primer and assuming abatement by the various techniques is additive.
  • This solvent based primer applied unabated using non-electrostatic spray equipment has a VOC of 4.8 lb./gal.
  • This primer using electrostatic application and assuming an increase in system transfer efficiency, say from 50 to 65%, could in effect lower the equivalent VOC of this material to approximately 3.7 lb./gal.
  • Utilizing backsection scrubbing abatement of 19% could lower the equivalent VOC of this primer, applied electrostatically, even further, say down to about 3.0 lbs./gal.
  • the solvent had been scrubbed even more effectively, as i.e. 32%, as observed in pilot trials the VOC emissions could possibly be reduced even as low as 2.5 lbs./gal.
  • Nalco 8735 and 8724 have the following characteristics:
  • Spectrograms of 18735 are characteristic of Sodium Carbonates.
  • 8724 compound is believed to be 10% by weight of polyaraine synthesized from the following materials:
  • V.O.C. (calculated lb/gal) 3.52 4 .93 3.84

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  • Coating Apparatus (AREA)

Abstract

Procede de revetement d'une piece de travail dans un compartiment de pulverisation utilisant une composition de revetement pulverisable, le compartiment communiquant avec un laveur a eau, l'eau de lavage permettant le contact entre les composants entraines par l'air de ladite composition de revetment pulverisable qui entre dans le laveur a eau et l'eau de lavage d'un epurateur humide a basse energie et volume eleve fonctionnant sous une difference de pression entre l'entree et la sortie de moins de, environ, 10 pouces d'eau. Plus particulierement cette invention se rapporte a une amelioration du procede de revetement qui comprend (A) la pulverisation dans le compartiment de pulverisation d'une composition de revetement lavable comprenant un compose organique volatile qui bout au-dessus d'environ 98 C a pression atmospherique, est soluble dans l'eau au-dessus d'environ 0,6% en poids a 20 C et est de nature transitoire dans l'eau de lavage; (B) la captation dans l'eau de lavage d'une partie volatile de ladite composition de revetement lavable dans laquelle la partie volatile comprend une quantite du compose organique volatile et dans lequel un ingredient dans l'eau de lavage reagit avec une partie de cette quantite; et (C) le maintien d'une concentration du compose organique volatile et des produits de reaction dudit compose organique volatile dans l'eau de lavage en-dessous de laquelle l'efficacite de captage tombe au-dessous d'environ 10% (de preference plus elevee, c'est-a-dire au moins 30%) d'une efficacite maximum.
EP80900752A 1979-03-23 1980-10-08 Procede de revetement d'une piece a usiner Expired EP0025066B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US2342479A 1979-03-23 1979-03-23
US23424 1979-03-23

Publications (3)

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EP0025066A1 true EP0025066A1 (fr) 1981-03-18
EP0025066A4 EP0025066A4 (fr) 1981-08-31
EP0025066B1 EP0025066B1 (fr) 1984-08-29

Family

ID=21815012

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80900752A Expired EP0025066B1 (fr) 1979-03-23 1980-10-08 Procede de revetement d'une piece a usiner

Country Status (5)

Country Link
EP (1) EP0025066B1 (fr)
JP (1) JPS56500287A (fr)
BR (1) BR8007659A (fr)
DE (1) DE3069051D1 (fr)
WO (1) WO1980001997A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4786926B2 (ja) * 2005-04-05 2011-10-05 本田技研工業株式会社 塗装設備

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA589560A (fr) * 1959-12-29 M. Arnold Orlan Composition d'agent chimique contenant un agent actif a la surface
US3421293A (en) * 1966-08-19 1969-01-14 Schweitzer Equipment Co Paint spray booths
US3985922A (en) * 1971-08-12 1976-10-12 Invirechem. Inc. Process for washing paint overspray from air
US4002490A (en) * 1975-02-20 1977-01-11 Nalco Chemical Company Paint spray booth chemical treatment
US4125476A (en) * 1977-03-10 1978-11-14 Dean Ralph R Paint spray booth composition
US4130674A (en) * 1977-08-17 1978-12-19 Detrex Chemical Industries, Inc. Process of controlling organic coatings in aqueous spray booth systems

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8001997A1 *

Also Published As

Publication number Publication date
EP0025066B1 (fr) 1984-08-29
DE3069051D1 (en) 1984-10-04
BR8007659A (pt) 1981-03-31
JPS56500287A (fr) 1981-03-12
EP0025066A4 (fr) 1981-08-31
WO1980001997A1 (fr) 1980-10-02

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