Mobile Zone - Optimized Spray Booth Control System For ... · Mobile Zone Designs into industrial facilities can be almost routine; enclosed is a Sverdrup brochure. I hope both of

Clyde Smith 1705 Green Hills Drive

Nashville, Tennessee 3721 5 61 5-385448

July 18, 1989

Mr. Roger Schecter North Carolina Pollution Prevention Pays Program Division of Environmental Management 512 North Salisbury Street Raleigh, North Carolina 27611-7687

Re: Mobile Zone Design as an example of Pollution Prevention

Dear Mr. Schecter:

For me, the theme of your program is that a more efficient and cost effective approach to pollution control lies in the virtually unexplored area of environmentally compatible industrial processes. This is a proposition which I also hold to be true. In fact, this theme has guided my specific research and development efforts for the last few years.

I have enclosed several copies of my technical paper entitled "Mobile Zone: Optimized Spray Booth Control System for Ultra-Efficient Surface Coating Operations" for your review and distribution. The paper describes a basic industrial process (surface coating) which I have redesigned to incorporate consideration of the environment, energy and worker safety. My redesign constitutes a 3 fold to 20 fold improvement over current designs. In this case, pollution prevention is attained through improved process containment. Since the improvement is so dramatic and the process so basic and pervasive, I believe the designs will eventually be widely considered a major technological achievement.

The path you describe is certainly better than the path our country is now on. To make your case more persuasive, examples of environmentally sound industrial processes would be most useful in illuminating the path you have laid out. These examples could also serve as beacons to guide others in redesigning industrial processes. I hope the Mobile Zone Designs will serve you as such an example.

In an effort to make cost effective, environmentally sound industrial processes available; both myself and my technical advisor Bill White have teamed with the Sverdrup Corporation. The Sverdrup Corporation which is the seventh largest U.S. design firm is convinced of the technical and economic value of these designs. Due to the great size and resources of Sverdrup as well as their industrial experience, incorporation of the

Mobile Zone Designs into industrial facilities can be almost routine; enclosed is a Sverdrup brochure.

I hope both of our efforts will prove synergistic. I look forward to the time when I may be of service to you.

Sincerely,

/La.-- =---_J /

Clyde Smith Box 150222 Nashville, Tennessee 37215 office 615-292-5568

Enclosures: Mobile Zone technical paper revision 2/28/89 with cost justification and resumes of Clyde Smith and Bill White

Mobile Zone Designs for Ultra-Efficient Surface Coating Operations revision 7/10/89

Contents

Summary . Introduction . VOC Emission Control Technology . " P A 3 3 . OHSA NFPA 33 and OHSA Variances. Spray Booth Design Mobile Zone Design Mobile Zone Design featuring Laminar Flow. Benefits Conclusion . References . Related Issues Illustrations .

Side Draft Booth Down Draft Booth

Cost Justification (optional) Resumes (optional)

Clyde Smith William White

Acknowledgements

This paper is the consolidation of presentations delivered at both the Air Pollution Control Associations 1988 Congress and the 1988 Aerospace Symposium sponsored by the U.S. EPA Region IX. I wish to thank Mr. James Berry of the U.S. EPA's Office of Air Quality and Standards, Research Triangle Park, North Carolina and Ms. Vickie Boothe of the U.S. EPA Region IX, San Francisco, Cali- fornia for their respective invitations.

I wish to thank the Technical Committee of the Society of Manufacturing Engineers for their invitation to present a Mobile Zone Design paper at their upcoming Finishing '89 national conference.

Copyright 1989, Clyde Smith

Mobile Zone Designs

Summary

Mobile Zone Designs are virtually closed loop, improved spray booth designs for manned su face coating operations. The d e s i p reduce capital and operating costs, increase production and reduce pollution, thereby saving time and money. These designs represent a mechanized, intermediate choice to the extremes presently available - manual or automated spray booths. These designs are characteristically simple, effective and inexpensive. Through these designs, industrial firms now have the opportunity to make signijicant progress toward the socially desirable goals of energy eficient and pollution pee industry.

Introduction

Mobile Zone Designs represent advanced, environmentally sound, manufacturing technology. The innovative concept is applicable to all ventilated work chambers where the ventilation is provided for the removal of noxious fumes and/or particles and the work chamber is provided for the benefit of worker and product. The most common ventilated work chambers in use are spray booths for painting, followed by booths for the lay up and spraying of fiberglass or composite products. The ventilated work chamber is improved by confining a zone (or path) of fresh ventilating air to just a portion of the cross section of the chamber, and providing means for shifting the location of the ventilating air zone from one place to another in the chamber, thereby serving the worker as he changes his location.

The Mobile Zone Design will reduce by 75 to 95+ percent the quantity of fresh air required to safely and efficiently ventilate the work chamber while complying with all NFPA 33l and OHSA2 standards. This means a spray booth using a conventional design will require 100,000 cfm while the same booth using a Mobile Zone Design may use as little as 4,000 cfm; this represents a 2,500 percent improvement. This will reduce the capital and operating cost of heating, cooling and VOC3 emission control equipment by the same percentage since these costs vary with the ventilation rate. This innovation will reduce the cost of temperature, humidity and pollution control normally associated with ventilated work chambers, thereby bringing these desirable features within the economic reach of everyone who desires such control.

The designs discussed in this paper represent a vanguard example of new

National Fire Protection Association Committee #33

Occupational Health and Safety Administration

Volatile Organic Compounds

- 1 -

Patents Pending on Mobile Zone Designs

thinking in advanced manufacturing technology. The designs represent a significant improvement in a basic manufacturing process common throughout the industrialized countries - surface coating operations. These designs reflect a concern for not only productivity, capital and operating cost but worker safety, environmental and energy concerns equally. This is a departure from current practice. Inclusion of safety, environmental and energy concerns as important element of redesigned industrial processes is a trend encouraged by leading U.S. scientists4. This paper focuses in detail on the energy and pollution aspects of surface coating; emphasizing how the Mobile Zone Designs can lead to reasonable cost, essentially pollution free surface coating operations through improved process design and containment. These designs are a direct result of a specific problem solving philosophy; a philosophy of proven efficiency and utility - minimize the magnitude of the problem before attempting to solve it.

The most effective and simple method of eliminating pollution from surface coating operations is to adopt essentially closed loop designs. The Mobile Zone Designs described in this paper represent the least costly, the most effective, broadly applicable, legal designs yet developed for manned operation meeting this criteria. The Mobile Zone Designs may be advantageously used in conjunction with VOC pollution control devices thereby allowing coatings chosen for their performance rather than VOC content. The specific Mobile Zone Design described in detail in this paper is but one of the related Mobile Zone Designs that can accommodate a wide variety of products and circumstances including small parts and small products (such as wood chairs), medium products (such as automobiles), large products (such as transport aircraft), side draft, down draft, continuous and batch operation. Illustrations of two such designs are at the end of this paper. The primary spray booth pollutants are Volatile Organic Compounds (VOC). VOCs are typically the solvent fumes from paints, thinners and cleaners ultimately exhausted from the spray booth stacks which photochemically react in the atmosphere of our environment creating ozone. The spray booth VOC emission problem has two major components: firstly, it requires effective VOC control; secondly, it requires an affordable price tag. The technological component of the problem has been solved by the vendors of regenerative incinerators and carbon adsorption units. The cost component of the problem has been solved by the essentially closed loop Mobile Zone Designs.

VOC Emission Control Technology

Existing VOC emission control technology is quite good and is readily available

Dr. Joel S. Hirschorn / Congressional Office of Technology Assessment / "The Case for Pollution Prevention" March/April 1989 EPA Journal

Dr. Sheldon K Friedlander / Parsons Professor of Chemical Engineering - University of California, Los Angeles / Director of Hazardous Substances Control sponsored by National Science Foundation / "Pollution Prevention - Implications for Engineering Design, Research and Education" May 1989 Environment

- 2 -


commercially. Combustion Engineering’s Air Preheater Division regenerative incinerator is a good example although there are others, such as Met-Pro’s KPR system and Calgon Carbon’s Cadre system. The Air Preheater units with the trade name of Combu-Changer are 95 plus percent plus effective in the destruction of VOCs by means of thermal oxidation. With an optional purge cycle, these units are 99 plus percent effective in the destruction of VOCs. The units work well throughout a wide range of ambient temperature and humidity conditions. They work well regardless of VOC concentration and throughout a wide range of exhaust air flow rates. The units have a long service life; they are mechanically simple and are highly reliable. The units work unattended with little routine or preventative maintenance required. In short, the Combu-Changer units in their present form represent an effective, and desirable control. Therefore it can be safely said that effective VOC emission control for spray booth exists and is readily available.

However, as effective as the existing control technology is, it represents only a partial solution to the spray booth VOC problem. The remaining problem is the high price tag. In fact, this has insured that spray booth VOC emissions are presently controlled only at a handful of sites throughout the entire United States. Based on current evidence, it is fair to conclude that ‘end of pipe’ treatment of VOC emissions, without any change to the process itself, is not practical. Installed VOC emission control equipment can cost of upwards of $40 per cubic foot of treated exhaust air. This translates into an installed cost per VOC source of between $200,000 and 10 million dollars and is beyond the means of many industrial frims. The prospect of reducing the capital and operating cost for treating a cubic foot of exhaust air is promising but may never be cheap. C-E Air Preheater’s Combu-Changer does have promise. The Combu-Changer design includes a relatively compact, partially insulated mild steel box filled with stones. This box is the regenerative incinerator. Dependent upon the quantity of stones installed, the regenerative incinerator is 90, 95 or 98 percent thermally efficient. With this level of efficiency, the VOCs provide all the fuel requirements to operate the incinerator. Designs such as this which efficiently use low cost materials in modest quantities have the potential to be economically manufactured. However, we must reduce the quantity of exhaust air to be treated5. The recirculation method and the Mobile Zone are two such approaches. These approaches differ from conventional spray booth design, therefore the issues addressed by NFPA 33 and OHSA must be considered.

NFPA 33

NFPA 33 writes standards for the design and operation of spray booths as they

Mr. Frank Gruszynski / Manager of Environmental Controls / LTV Aircraft Products Group / paper presented at 1988 Aerospace Symposium

- 3 -


relate to workplace safety, specifically the fire and explosion issue. The principal objective of the NFPA 33 standards is that under no circumstances should there be a volatile concentration of over 25 percent of the Lower Explosive Limit (LEL) in the exhaust stream. To achieve this objective a number of design standards are suggested. NFPA 33 has no enforcement powers; however a number of organizations which do have coercive powers have adopted NFPA 33 standards. These organizations include the local fire department which enforces the fire codes, the factory insurance com- panies and OHSA.6

OHSA

OHSA is a governmental organization which has regulations for the design and operation of spray booths as they relate to workplace safety, specifically the worker toxic chemical issue. The OHSA regulations include some of the NFPA 33 standards in addition to its own. The principal objective of the OHSA regulations is that under no circumstances will a worker be exposed to a solvent concentration of over 100 parts per million (ppm) during an eight hour shift or solvent specific peak exposures. To achieve this objective a number of design standards are suggested.

NFPA 33 and OHSA Variances

Variances are granted to the spray booth owner upon petition to the appropriate authority to achieve the objective by a different means than is described in the standards or regulations. Variances are not granted for failure to meet the objectives of the NFPA 33 standards or OHSA regulations. It is up to the booth owner or his agent to convince the authorities to grant a variance; it is by no means automatic. In fact, a variance once granted can be revoked at any time. Should disaster strike, the booth owner is in a weaker position from the liability point of view if he is operating under a variance.

Spray Booth Design

To set the Mobile Zone Design in perspective, the following describes its place among the two contending operational methods - conventional and recirculation. At one extreme, a conventional spray booth utilizes fresh air across it entire cross section for the benefit of the worker and his work activity. The many improvements described in practice and disclosed in the patent literature illustrate means for dividing this cross section into fixed or rearrangable zones of varying velocities to minimize total air

Mr. William White / Secretary of National Fire Protection Association Committee #33 / June 1988 conversation with author

- 4 -


consumption. Unfortunately, in each case these methods reduce the air flow by only 10 to 30 percent and additionally they are limited by product, scale or industry. At the other extreme, a recirculation booth utilizes recirculated air across its entire cross section for the benefit of the work activity; separate fresh air must be supplied through a flexible hose to a "space suit" which the worker occupies. From the practical point of view, the worker is so encumbered the suit, suit hose, spray equipment and spray equipment hoses that he can barely do his job. However, the recirculation method is very efficient with broad application and air flow reduction of up to 95 percent. Unfortunately, the recirculation design does not meet OHSA standards and as a result a variance form OHSA is required to legally operate this type of booth. OHSA no longer provides variances for recirculation designs due to the heightened concern over the method's inherent dangers.' OHSA's reasoning is that intentionally placing a worker in a contaminated environment on a day by day basis with such insubstantial protection is too risky. It should be noted that the recirculation design is successfully and economically employed on an unmanned robotic basis by a number of the giant manufacturing corporations with a high volume of standardized products such as automobiles. However, the Mobile Zone Designs can be advantageously deployed in the manual touch up and detail station following the robot station. For the rest of industry, the Mobile Zone Design offers a simpler alternative to the inflexible operation and much higher capital and operational cost of robotic systems.

The Mobile Zone occupies the operational method between these two extremes. It provides fresh air for the benefit of the worker and his work activity across only a portion of the work chamber cross section. In addition, the zone of fresh air shifts in location respective of the workpiece responsive to the shifting locational needs of the work activity. Additionally, the balance of the cross section may optionally be ventilated with recirculated air. Therefore the Mobile Zone Designs use features common to each extreme in a unique combination. It improves on the safety of a conventional spray booth while avoiding its extravagant waste. It is as efficient as the recirculation method without its inherent danger.

For most industrial production equipment, choice is available for degree of mechanization; there is a clear progression from manual, to mechanized, and finally to automated. However, for surface coating operations, there has been a gap in the middle between a conventional, manual booth and automated robot booth. Again, the Mobile Zone Design fills this gap between the two extremes by providing mechanized mobility to the worker.

To further delineate the fundamental differences in the conventional design, recirculation design and the Mobile Zone Design, one may consider how the exhaust rates are determined. For the convention design, the exhaust rate is set by the size of

' Mr. AI Tremblay / Office of Federal Agency Programs / Occupational Health and Safety Administration / Washington, D.C. / September 1988 conversation with author

- 5 -


the ventilated cross section of the work chamber. In such a design, the exhaust rate is essentially proportional to the size of the booth which is sized for the largest expected workpiece plus work space for the worker. For the recirculation design, the exhaust rate is set by the quantity of fresh air required to dilute the ventilation air below 25 percent of the LEL. In this design, the exhaust rate is essentially proportional to the level work activity (spray rate). For the Mobile Zone Design, the exhaust rate is set instead by size of the access area required by the worker. The exhaust rate is proportional to the number of workers who must work simultaneously.

Mobile Zone Design

For work activity which requires ventilation, the Mobile Zone Design provides a zone of fresh air within a work chamber for the benefit of a worker and his work activity. The work activity contemplated includes surface coating, surface stripping, surface cleaning as well as manufacturing and fabrication operations which require ventilation such as the spray and "lay-up" of fiberglass or composite products. This zone of fresh air shifts in response to shifting locational needs of the work activity. A moveable opening confines a zone of fresh air which flows over the worker and work activity. Additionally, the opening may be in a structure which serves as a conduit for the fresh air, a passageway for the ingress and egress of the worker and mobile work platform for the worker. In this way, the linkage between work chamber size and quantity of air exhausted to the atmosphere is broken. An alternative description is an improved work chamber combining a smaller mobile work chamber within a larger stationary work chamber. The smaller mobile work chamber provides additional zone definition. In the most beneficial embodiments, the smaller work chamber is occupied by the worker while the larger work chamber containing the product remains unoccupied. This differs substantially from conventional design, since the introduction of fresh mobile zone air into the booth is limited to the area of the spraying activity and the openings for the entrance and exit of product. Recirculation can be incorporated with the Mobile Zone Designs to promote laminar flow and provide additional overspray control. In this way, the cross section of the booth (work chamber) can be ventilated with fresh and recirculated air components.

The most efficient and advantageous embodiments of the Mobile Zone Designs include a manned mobile work chamber within a larger unmanned, stationary work chamber and incorporate recirculation. These designs represent as nearly a closed loop system as is currently practical.

Mobile Zone Design featuring Laminar Flow

Common surface coating operations utilize a side draft booth in which the workpieces hang from an overhead conveyor. The work pieces are coated by the

- 6 -


worker pacing back and forth as the work pieces are slowly conveyed through the booth. Illustrations of this improved design can be found on pages 18 and 19.

In addition to the feature where a zone of fresh air follows the worker as he paces back and forth in the work chamber, a further refinement includes the worker riding in this zone of fresh air. The motion of pacing back and forth can be replaced by a motorized platform which shuttles back and forth in the work chamber on tracks. The hoses normally dragged by the worker can also be attached to the work platform and their weight borne by a festoon system connecting the chamber and mobile work platform. This festoon will serve the control system wiring as well. This would free the worker from fatigue of pacing back and forth and the hinderance of dragging the hoses. Typically, efforts of this nature result in improved productivity.

To positively insure the safety of the worker, the application equipment may be tethered to the cab thereby allowing freedom to apply coatings while he is within the cab while prohibiting it outside the cab. Alternatively, a pressure switch mat or infrared sensor switch may monitor the cab on a "deadman" switch basis interlocked with application equipment. This would prohibit use of the application equipment while the cab is unoccupied.8

Control of the movement of this mobile work platform may be manual, automatic or a combination. Manual control may be accomplished by mounting a hand or foot operated joy stick on the mobile work platform. By deflecting the joy stick in one direction, motion of the work platform is established. The rate of motion may be proportional to the degree the joy stick is deflected. Automatic control may be accomplished by moving the work platform in a preprogrammed sequence with respect to direction and rate. Automatic control is most beneficial when the workpieces and work activity is regular and repetitive.

For the worker to ride in a zone of fresh air requires that the mobile work platform be in the form of an open cab with a floor, walls and ceiling also referred to as the "mobile work chamber". This cab defines the opening through which fresh air is delivered into the work chamber. In this example, the opening is an opening in a flexible curtain to which the cab is attached. This curtain accomplishes the required back and forth motion by alternately winding up and paying out from rollers. This assembly is configured as two vertically disposed rollers at each side of the work chamber with the curtain stretched between. To move the curtain and the cab attached to it; the curtain will wind up on one roller while paying out from the other. To change directions, the reverse procedure is applied.

To incorporate recirculation, a second duplicate curtain assembly must be located in the chamber, interior to the first curtain. Both curtains will move in unison.

Mr. Dennis O'Brien / National Institute of Occupational Safety and Health / Cincinnati, Ohio / November 1988 conversation with author - Mr. O'Brien suggested positive safety features be included on the mobile work platform

- 7 -


The chamber formed between these two curtains will receive the recirculated air from a duct and fan connected to the exhaust chamber. The inner curtain will be perforated to function as a diffuser to uniformly distribute the recirculated air. With careful sizing of the recirculating fan means, perforation size and spacing, the perforated curtain wall can distribute the recirculated air uniformly regardless of the cab position within the work chamber.

In this design, the entire cross section of the work chamber will be ventilated. The ventilation will be comprised of a fresh component and a recirculated component. The fresh air will enter the work chamber through the cab and other openings in the work chamber such as those for the entrance and exit of workpieces. If the ratio of recirculated air to fresh air is high, the overspray filter will commonly be a high efficiency, multi-stage, dry filter. High particdate removal efficiency is important to prevent the overspray from becoming a dust source in the recirculated air as it repeatedly passes over the workpiece. A dry filter, rather than a wet filter, is desirable to prevent an excessive increase in humidity in the recirculated air as it repeatedly passes through the filter.

As an example, for a side draft booth with a cross section of 10 feet high by 15 feet wide, the total air flow would be 22,500 cubic feet per minute based on 150 square feet of cross section at 150 feet per minute ventilating velocity. Assuming only one painter at a time used this booth, then only one cab would be required. If the cab dimensions were 4 feet wide and 7 feet tall, then the fresh mobile zone air flow would be 4,200 cubic feet per minute based on 28 square feet of cross section at 150 feet per minute ventilating velocity. Thus for the total air flow of 22,500 cubic feet per minute, the recirculated component will be 18,300 cubic feet per minute with a fresh component of 4,200 cubic feet per minute. As a result, with the Mobile Zone Design, every minute 4,200 cubic feet of fresh air is introduced into the booth and the same amount of spent exhaust air is discharged to the atmosphere. This compares to 22,500 cubic feet per minute of air which is required in a conventional booth. This represents an 81 percent reduction in the ventilating air required to safely and legally operate the booth under current regulations and standards.

Benefits

Production quality may be maintained or improved. Since the Mobile Zone Design provides air over the spray gun in a direction predominately parallel to the spray gun’s operating direction, both paint transfer efficiency and accuracy should improve due to less distortion of the spray pattern. Quality is again improved by the essentially, laminar flow of the mobile zone air which is free of workpiece induced turbulence such as is found on the lee side of workpieces in a conventional booth. Productivity will improve since the Mobile Zone Design provides mechanized mobility to the operator to speed access to the product’s surface and reduce fatigue. Additional-

-

- a -


ly, by programming the sequence of movement, management can gain greater control over the scope of the worker’s activity and his pace, thereby increasing quality and productivity while maintaining a schedule.

The cost of owning and operating a spray booth will be substantially reduced since the Mobile Zone Designs will reduce the ventilating air required by between 75 and 95+ percent. In turn, this will reduce the capital and operating cost of heating, air conditioning and pollution control equipment by a like amount. These costs represent a major portion of the costs of a surface coating facility and a principal area of energy consumption in a manufacturing plant. Over a period of years the energy costs saved by the Mobile Zone Design alone will be several times greater than the initial capital cost of the surface coating facility. Many industrial firms presently must choose between either products with inferior surface coatings or production schedules subject to the whims of the weather because they can not afford humidity and temperature control such as air conditioning. The Mobile Zone Design will make this climate control affordable, again improving productivity and quality.

The Mobile Zone Designs break the linkage between booth size and exhaust air rate, thereby allowing larger booths without penalty. No longer is it necessary to have a group of different sized spray booths for different sized parts. Consolidation of booths is possible; again, reducing the cost of owning and operating a spray booth.

The objectives and regulations of the EPA are met by making abatement practical and affordable. This is accomplished by reducing the quantity of polluted air requiring treatment and by concentrating the VOC stream for use as incinerator fuel. The objectives and standards of NFPA 33 are met by introducing the required fresh air to keep volatile concentrations below 25 percent LEL. In fact, fire and explosion danger is greatly reduced since the spray booth work chamber is contained and isolated from the rest of the facility to a much greater degree than is possible with a conventional design.

The objectives and regulations of OHSA are met by providing both fresh air over the worker and his spraying activity as well as a physical barrier between the worker and contamination. In fact, worker safety is greatly enhanced compared to a conventional design since the worker is provided with a smoke and fire free path from the booth. Additionally, by design the fresh mobile zone air always passes first over the worker’s breathing zone and then to the work area providing positive protection to his breathing zone. This is in sharp contrast to conventional design where by common practice the worker often is downstream of his spraying activity and the overspray is blown back over him thereby contaminating him and his breathing zone.

Something Old - Something New

The important features of the Mobile Zone Designs include recirculation, dry filtration, mobile work platform and fresh ventilating air delivered to the mobile work

- 9 -


platform typically through an articulated corridor. Individually, most of these features are included in new and upgraded conventional surface coating facilities every day. For instance, recirculation is widely employed in robotic and automatic coating installations. These installations include the most demanding, high quality applications. Dry filtration is commonly specified with new booths and often retrofitted into existing booths to replace wet filtration. Mobile work platforms are also commonly used in applications requiring speedy access for the operator. As one example out of hundreds, mobile work platforms in the form of stacker cranes are used to paint the McDonnell Douglas transport aircraft and the stacker crane system is given much credit for the finish on these planes which is considered to be among the best in the industry. The delivery of fresh ventilating air to the mobile work platform and the means of moving the mobile work platform are new. Yet this newness is well within the accepted limits of engineering art. The Mobile Zone Designs are more familiar than unfamiliar and qualify as mainstream design.

Conclusion

Mobile Zone Designs are improved spray booth designs for surface coating operations. The designs reduce capital and operating costs, increase production and reduce pollution, thereby saving time and money. These designs represent a mechanized, intermediate choice to the extremes presently available - manual or automated spray booths. These designs are characteristically simple, effective and inexpensive. For the industrial firm, high pollution control costs are no longer a barrier to cleaning up VOC emissions and VOC emissions are no longer a barrier to economic growth. Creating wealth means doing more with fewer resources; industry can benefit from the "waste not - want not" result of waste reduction. By significantly reducing pollution and energy usage, the Mobile Zone Designs provide industry with a positive step toward future prosperity.

Surface coating operations are a good example of a pervasive industrial problem - a production activity of modest daily impact yet one of enormous long term, cumulative impact. Daily, surface coating operations decrease our fossil fuel inventory while increasing our toxic chemical inventory. As a matter of civic responsibility, one would think that industry would voluntarily address and solve this problem. Yet, improvement in this area typically occurs reluctantly and as a result of regulatory action. Certainly, no one wishes to leave as our legacy for future generations - a world which is out of fuel and poisoned.

- 10 -


References:

Clyde Smith - DesignManufacturing Engineer & Mobile Zone Designs inventor

Mailing : Box 150222 Nashville, Tennessee 37215

Telephone: Office (615)-292-5567 Home (615)-385-4048

Patent:

The designs of the present invention are broadly claimed in the pending application and operationally include the area between conventional design and recirculation design. The inventor’s patent attorney is Mr. John Behringer of Sutherland, Asbill & Brennan of 1275 Pennsylvania Avenue, Washington, D.C..

License:

License for the manufacture, sale and/or use is available under reasonable terms to interested parties with proven ability. This includes both the job by job and the continual basis. License arrangements will be made in a simplified and expeditious manner.

Design Consultants:

In the absence of any specific arrangements, design services for the Mobile Zone as well as other finishing issues are available on a consulting basis at a rate of $100 per hour plus approved expenses at cost - contact Clyde Smith.

Partial List of Major Paint Booth Manufacturers:

Air Industries Systems Corp. Binks Manufacturing Cincinnati Industrial Machinery Haden Schweitzer DeVilbiss Company J.B.I. Incorporated DURR Industries Protectaire Systems Flakt Inc., Alpha Division

A.B. Myr Industries George Koch & Sons, Inc.

TKS Industrial Company

- 11 -


Partial List of VOC Emission Control Equipment Manufacturers:

Amcec REECO C-E Air Preheater Calgon Carbon Vara International Flakt Inc., Alpha Division Ross-Waldron Hirt Combustion Engineers Nobel Chematur Met-Pro DURR Industries Thermal Precision-Quincy Haden Schweitzer

Smith Environmental Corp.

Related Issues

The spray booth and its ventilation system provides for the containment and capture of the VOCs. The spray booth is the device that actually causes the contamination of huge quantities of air. Although the "scene of the crime" is the spray booth, other factors enter into the total environment impact. A number of ameliorative steps have been proposed.

Use Less Paint:

Less VOCs are emitted into the air if less paint is used; this is accomplished by several means. One option is to apply thinner coatings consistent with expected service life of the product. A second option is to use higher quality paint that can do the same job with a thinner film thickness. A third option is to use a higher performance paint which lasts longer between maintenance coatings. A fourth option is to use higher efficiency application equipment which applies more of the paint that is used to the product e.g. transfer efficiency. Common application equipment includes the following in their approximate order of increasing efficiency: air, air assisted airless, high volume- low pressure and electrostatic. Transfer efficiency commonly cited range from 40 to 90 percent. Less commonly cited is the role the product and worker plays. A difficultly shaped product or poor worker technique can cut transfer efficiency in half or worse.g Although the relative transfer efficiencies for application equipment can be approximately calculated, the absolute transfer efficiency can typically only be determined by actual field trial. Alternative application equipment can be used which has almost 100

Mr. Jan Piker / Marketing Manager / Electrostatic Finishing Division / Gram Inc. / paper presented at 1988 Aerospace Symposium

- 12 -


percent transfer efficiency, product shape independence and worker technique independence. This equipment includes dip tank, brush and roller.

Use Less Toxic Paint:

Less VOCs are emitted into the air if less VOCs are in the paint. Powder coatings or reformulated coatings, e.g., high solids and water borne which meet EPA specifications are typically called "compliant coatings". The specifications as to VOC content are likely to call for less as time goes by, necessitating repeated reformulations. Reformulated compliant coatings do not contain the staggering amount of VOCs that conventional coatings do; however, they still contain a substantial amount of VOCs. The question becomes whether the ozone standards can be met through substantial improvement via compliant coatings or whether it will require the near zero emissions attained through control device abatement. There is little question that compliant coatings are method of choice for the low volume, occasional or intermittent applicator of surface coatings. For production applications, the method of choice is not so clear. For instance, in the long run, will the EPA accept a situation in which one manufacturer using compliant coatings emits nearly 2,200 percent more VOCs than another manufacturer of equal production capacity using conventional coatings coupled with an abatement device?1° Additionally, there are increased costs associated with compliant coatings which diminish their attractiveness. Such increased costs cited to date include; shorter service life, less corrosion protection, degraded surface appearance, increased paint cost, increased surface preparation and more difficult application.ll

Use Abatement Equipment:

VOC contaminated air can be treated by an abatement device before release into the atmosphere. As a result, VOC abatement equipment renders surface coating operations essentially pollution free. Additionally, abatement equipment allows the freedom to use any coating - compliant or not. In this way, the coating may be chosen on the basis of its performance rather than its VOC content. Typically, the abatement equipment destroys rather than recycles the VOCs and this destruction is by thermal oxidation methods although biological conversion has been attempted. Oxidation of VOCs occurs at temperature between 1400 and 1800 degrees F. If a catalyst is used, the temperature can be reduced to approximately 600 degrees F. In both cases heat recovery is often used to reduce fuel consumption of the oxidizer. One method of heat

lo Mr. Neil Moyer / South Coast Air Quality Management District - California / panel discussion at 1988 Aerospace Symposium / this agency may adopt Best Available Control Technology standards ( B A T which is presently control equipment

l1 Mr. G. W. Parker / Account Executive / DeSoto Inc. / paper presented at 1988 Aerospace Symposium

- 13 -


recovery uses recuperative, shell and tube or plate and fin, heat exchangers. Another method uses a regenerative, mineral media, heat exchanger. As an alternative to subjecting all the contaminated air to oxidation temperatures, carbon adsorption is used. The contaminated air is passed through an activated carbon bed filter which adsorbs the VOCs; periodically the bed is desorbed and the concentrated VOC stream is processed by an oxidizer.

Illustrations

Perhaps this Mobile Zone Design can be understood better through the use of the accompanying illustrations on pages 18, 19 and 20. The Mobile Zone Designs illustrated include a typical small, side draft booth and a typical large, down draft booth. Specifically, Figures 1 through 4 illustrate a side draft booth suitable for small to medium sized workpieces. Figure 5 illustrates a booth suitable for large workpieces.

Mobile Zone Side Draft with Laminar Flow

Figures 1 through 4 illustrate a small, side draft booth of a Mobile Zone Design with recirculation. This size booth is typically used for small to medium size workpieces. These workpieces may be parts, assemblies or finished products which range in size from inches to several feet. Tool boxes, chairs, auto engines, lamps, lawn mowers and motorcycles are typical examples. The illustrated design utilizes only one degree of freedom or, in other words, a back and forth motion. Utilizing only one degree of freedom limits the working depth to the arm’s reach of the worker. As a result, this specific design is limited to workpieces which are shallow in depth. Of course, there is no problem in adding additional degrees of freedom to accommodate workpieces with greater depth.

Figure 1 illustrates schematically a side draft booth. Fresh air is drawn into the booth from the atmosphere by fan 17. At the face of the booth, two curtain walls 55 and 56 are located. An opening through both curtain walls is defined by a cab 57. In response to manual control input by the worker, the cab 57 moves at the rate and in the direction selected by the worker to provide proper access to the workpieces in the work chamber 53. In conjunction with the movement of the cab, each curtain wall 55 and 56 winds up on one drum and pays out on the other drum. Curtain wall 56 forms the upstream boundary and curtain wall 55 forms the downstream boundary of recirculation chamber 70. Exhaust air enters each side of the recirculation chamber 70 by means of conduit 54.

The volume of air entering each recirculation chamber is controlled by flow control damper 60 in response to the proportion of each curtain surface area exposed in curtain wall 55. The recirculation air 59 exits the recirculation chamber 70 into the

- 14 -


work chamber 53 through perforations in the curtain surface of curtain wall 55. Fresh mobile zone ventilating air 57 enters the work chamber 53 from the atmosphere through the cab 57. The entire work chamber is uniformly ventilated throughout its cross section by a combination of recirculated air 59 and fresh air 58. This ventilating air is pulled from the work chamber through the exhaust chamber 13 and through filter 15 by fan 17. The filter 15 removes the overspray. A small portion of the ventilating air is exhausted to the atmosphere through exhaust stack 19. The volume of exhaust air may be controlled by flow control damper 18 in the exhaust stack 19. The remaining portion of the ventilating air is returned to the recirculation chamber 70 though conduit 54. The ratio of air exhausted to air recirculated is proportional to the ratio of opening area as defined by the cab 57 in the curtain walls 55 and 56 to the total area of perforated curtain surface in curtain wall 55 in the booth cross section.

The pictorial representation of Figure 2 illustrates the Mobile Zone mechanism alone; separated from the conventional booth.

Figures 3 & 4 illustrate pictorially the schematic design of Figure 1 to show the physical interrelation and operation of the Mobile Zone Design. Figure 3 is a frontal isometric view and Figure 4 is a sectional side view. Referring to Figure 3, suspended from the ceiling 183 is a monorail conveyor 184 with trays 185 that slowly transport the workpieces to be sprayed (not shown) through the booth. Monorail 184 extends through the booth. Booth end walls 186 have openings 187 for the passage of the conveyor trays 185. The operator 188 (shown only in Figure 4) rides back and forth the full cross section of the booth in a motorized cab which is comprised of floor 189, walls 190 and ceiling 191. The worker sprays the workpiece from his vantage point in the cab. Like partitions, the cab further defines the opening in the curtain walls. In this instance, the cab has the dimensions of four feet wide and eight feet high. The walls 190 of the cab have windows 194. The cab is equipped with manual operator control input (not shown) such as a foot switch to signal the controller 195 which will in turn cause the cab to stop or move it in a particular direction and speed.

The curtain walls are comprised of curtain surfaces 192 and 193 which are fabricated from narrow interlocking steel slats. These curtains surfaces 192 and 193 spool in and out from drums inside housing 196. Tension is maintained on these curtain surfaces 192 and 193 by tensioning devices 197 connected to the drums. The curtain surfaces and the cab operate in tracks 198. A recirculation chamber 199 is formed and bounded peripherally by the floor, walls, ceiling and the two curtain walls. The downstream curtain wall 192 is perforated to permit exit of the recirculated air supplied by recirculation duct 200 from exhaust fan 201. By careful sizing and spacing of the holes in the perforated curtain wall 192, the curtain wall will act as diffuser to evenly distribute the recirculated air across the booth cross section thereby eliminating turbulence and the possibility of fugitive overspray.

- 15 -


Referring to Figure 4, the overspray laden air is drawn through the exhaust chamber 202 by an exhaust fan 201 to exit to the atmosphere through the exhaust stack 203. The exhaust chamber 202 is separated from the work chamber 204 by the lower wall portion 205. A pool of scrubbing water 206 stands in the exhaust chamber 202. The water is recirculated by pump 207 to spray header 208. The spray constantly wets baffles 209 and 210 which along with the spray constitute a water wash filter, which extends the entire length of exhaust chamber 202. Openings (not shown) near the bottom of baffle 209 allow water 206 to stand at the same level throughout exhaust chamber 202.

Mobile Zone Down Draft with Laminar Flow

Figure 5 illustrates a large, down draft booth of a Mobile Zone Design with recirculation. This size booth is typically used for medium to large size workpieces. These workpieces may be parts, assemblies or finished products which range in size from several feet to several hundred feet. Automobiles, tables, tractors, artillery, desks, trucks, aircraft, tanks, missiles and airliners are typical examples. The illustrated design utilizes three degrees of freedom or, in other words, a back and forth, up and down, in and out motion. Utilizing three degrees of freedom allows access to the top, bottom, sides, front and back of the workpiece. The most prominent feature of this Mobile Zone Design is the articulated corridor and cab. As shown, the articulated corridor resembles in form and movement the human arm. Note the joints in the articulated corridor which correspond to the shoulder, elbow and wrist joints of an arm.

Figure 5 is a partially broken away sectional isometric of a Mobile Zone booth with recirculation. This is a typical batch type down draft booth. Doors (not shown) are opened to allow entrance of the workpiece. With the product in the work chamber, the doors are shut and work commences and is continued until completion. Upon completion the doors may be opened and the workpiece removed, thereby readying the booth for a repeat of this production cycle.

While work activity is taking place in the work chamber, fresh mobile zone air 245 enters the articulated corridor 246 through an opening in the spooling type panel comprised of opening frame 247, curtain surfaces and track-drum housing 249. The spooling type panel is mounted in the booth wall 250. The frame 247 moves up and down in this spooling type panel. Curtain surfaces 248 provide the seal for this movement. Attached to frame 247 is a pedestrian platform 251 and attached to this platform 251 is a hinged and wheeled pedestrian ramp 252. The ramp and platform provide the workers with convenient access to the articulated corridor regardless of the elevation of the opening in the spooling type panel. "he articulated corridor is attached to the frame 247. The frame both provides support to the articulated corridor and raises and lowers it by means of an actuator (not shown).

The articulated corridor is comprised of multiple corridor segments 246 with

- 16 -


floor, walls and ceiling, multiple swivel joints with their actuators 254 and cab 255. The worker will ride in the work platform cab 255 with window 256. The cab’s vertical movement is provided by the frame 247 which raises and lowers the cantilevered, articulated corridor along with the cab 255. In this embodiment, the entire articulated corridor and cab always remain horizonal. The actuator powering the vertical movement of frame 247 is not shown. The cab’s horizonal movement through the cross section of the work chamber is provided by the extension, retraction and rotation resulting from the combined action of the corridor segments 246 and their swivel joints 253 under the power of actuators 254.

The work platform cab 255 will be brought into working positions by either the manual control input of the worker or by means of an automatic control input which follows a preprogrammed sequence. The mobile zone air 257 will exit the cab 255 horizontally; however it will soon be deflected downward by the overwhelming mass of recirculated booth air moving vertically from ceiling to floor. Throughout the entire cross section of the work chamber, the recirculated air travels downward finally exiting through the floor grating 258 and into the exhaust chamber 259. Contained in exhaust chamber 259 is the overspray filter where particulates are removed. Filtered exhaust air is drawn up by the recirculation fans 260 and discharged into the recirculation chamber 261. The recirculation chamber 261 is formed by the booth ceiling 262, booth walls 250 and the diffuser assembly 263. The diffuser assembly is made up of a lattice support grid fitted with either diffusers or filters.

The recirculation air is evenly distributed throughout the work chamber cross section into the work chamber in a downward direction. Part of the contaminated air from exhaust chamber 259 is drawn off by exhaust fan 264. This exhaust air 265 is discharged to pollution control equipment or to the atmosphere through stack 266. The quantity of exhaust air 265 exhausted is equal to the quantity of fresh air 245 introduced into the work chamber by means of the Mobile Zone mechanism comprised of a spooling type panel, an articulated corridor and work platform cab 255.

-

-

- 17 -


I 19

18

/ 5-

- 57

Fig. 1 9

recirculation duct

unperforated curtain perforated curtain recirculation chamber

motorized cab

- 18 -

Patents Pending

200, fi 203

- 19 -

Patents Pending

- 20 -

Patents Pending

I

Cost Justification - Mobile Zone Designs

Summary

Cost justification is a mathematical procedure used to objectively select capital equipment based on its financial value to the buying company. The appropriate equipment is that which has the lowest combined capital and operating cost. By this measure, the Mobile Zone Designs represents the prudent choice and best value in virtually all cases.

Cost Basis

A surface coating facility or finishing line will always be comprised of a ventilated booth and may optionally contain heating, cooling and pollution control equipment either singly or in combination. The design of the spray booth typically determines the ventilation rate and therefore the size of the heating, cooling and pollution control equipment. The heating, cooling and pollution control equipment has substantial operating costs in addition to its capital costs. As a result, both capital and operating cost can and typically are express in terms of ventilating rate; i.e. dollars per cubic foot per minute ($/cfm) of ventilating air. This serves as a common basis upon which to make mathematical calculations and comparisons.

The Mobile Zone Designs represent an additional effort and expense beyond the cost of the spray booth alone. The cost justification question is whether this addition expense can be recouped from the saving in capital and operating costs for heating, cooling and pollution control. The following table illustrates typical installed capital costs per CFM and operating costs per CFM per year based on 4000 hours of operation per year.

Table #1 Typical Capital and Operating Costs

Capital per CFM 1. Heating $1.00 $0.60 2. Cooling $5.00 $1.40 3. Pollution Control $35.00 $2.00

Operating per CFM per Year

Mobile Zone Costs

Presently, the typical installed cost of a Mobile Zone Design may range from $1.00 per CFM to $2.50 per CFM. In time, the Mobile Zone Designs will be available as a standard catalog items with the lower cost that standardization brings; then the Mobile Zone will always be the best choice. There are no operating costs associated with the Mobile Zone mechanism. The Mobile Zone Design will typically reduce the ventilating air consumption by 85 percent; thereby reducing the capital and operating costs for heating, cooling and pollution control by 85 percent.

Calculations

Cost justification of the Mobile Zone Designs requires that either of two cases are true. First, the capital costs with the Mobile Zone Design must be less than the capital cost without the Mobile Zone Design, i.e. conventional. Second, if the capital cost with the Mobile Zone Design is higher, then the difference must recouped from lower operating costs within a reasonable time which is typically three years, i.e. three year payback.

Since cost justification is almost always comparative, the following illustration of cost justifications will be comparative. The comparison is between a two equally sized booths using heating only. One of these is of conventional design and one is of Mobile Zone Design. As an example, a conventional design will use 20,000 CFM while the Mobile Zone Design uses 3,000 CFM using the assumed 85% reduction and using an assumed Mobile Zone cost of $2.00 per CFM. The following table illustrates the installed capital and three year operating costs and indicates selection of the Mobile Zone Design.

Table #2 Worst Case Justification - Heating Only

Conventional - 20,000 CFM Mobile Zone - 3,000 CFM

1. Heating - Capital 2. Heating - Operating 3. Mobile Zone - Capital

4. Total

$20,000 $36,000

$56.000

3,000 $5,400

$40,000

$48.400

For completeness, a furtrler comment is approprde on the issue of cost justification. Rigorous cost justification calls for consideration of the time-value of money, rate of return, maintenance cost, service life and salvage value in addition to capital cost and operating cost. Rigorous justification is appropriate for selections which are close in value and can benefit from the extra discrimination provided by rigorous justification. In the case of the Mobile Zone Designs, the superiority of the Mobile Zone Designs is so overwhelming that rigorous justification will not change the outcome and therefore is unnecessary.

Conclusion

On the basis of cost justification, the Mobile Zone Designs are always the correct choice whenever cooling or pollution control are involved singly or in combination. When heating alone is involved, the Mobile Zone Designs are the correct choice except when the yearly operating costs for heating are extremely low. Low yearly operating costs may be the result of low energy prices or few operating hours per year such as caused by intermittent use or a short heating season.

Mobile Zone and VOC Abatement - Cost Guide 3/89

The following example represents estimated costs for VOC abatement; the Mobile Zone clearly makes abatement practical, affordable and cost competitive. In this example, the Mobile Zone Design saves $1,475,000 on initial capital cost. Whereas a conventional design will have a capital cost of $1,750,000; the Mobile Zone Design will have a capital cost of $275,000 which is an 84% cost reduction. Over a ten year period, the Mobile Zone Design will save $1,350,000 in operating costs. Whereas a conventional design will incur operating costs of $1,500,000; the Mobile Zone Design will incur operating costs of $150,000 which is an 90% cost reduction. 4

Estimated Cost Ranges:

1. Figure 2000 to 3000 CFM which must be treated per painter working

2. Figure $25 to $45 per treated CFM for installed VOC control devices. 3. Figure $1.50 to $2.50 per CFM of original ventilation for Mobile Zone

simultaneously.

mechanism.

Example:

Consider a manufacturer who operates one spray booth. The booth exhausts 50,000 CFM. At any time, 2 painter may work in the booth. The booth is operated 3 shifts per day 5 days per week employing a total of 6 painters.

Using the median of the estimated cost ranges, the abatement option is calculated as f0lloWs:

$175,000

$100,000

$275,000

1. Since 2 painters can work simultaneously, then 5,000 CFM of ventilating air is contaminated and must be treated. This is the result of 2 painters times the median 2,500 CFM per painter.

2. Using the median cost of $35 per treated CFM times 5,000 CFM of treated CFM yields a result of $175,000 for installed VOC abatement equipment.

3. Using a median cost of $2 per CFM of original ventilation times 50,000 CFM of original flow yields a result of $100,000 for installed Mobile Zone mechanism.

Total Cost for Mobile Zone and VOC Abatement (without the Mobile Zone, VOC Abatement will cost $1,750,000)

Clyde M. Smith

Professional Background

0

0

0

0 General Contractor License (unrestricted) 0

0

BS, Industrial Engineer, Georgia Institute of Technology, 1974 Member of Society of Manufacturing Engineers - Finishing Processes Member of Air and Waste Management Association

Invented and patented Mobile Zone control system for VOC Emissions Technical Papers presented at national conferences to nationally recognized associations:

6/24/88 Air Pollution Control Association’s 1989 Congress 11/14/88 Aerospace Symposium sponsored by EPA Region IX 9/10/89 Society of Manufacturing Engineers’ Finishing ’89

Environmental Protection Agency Department of Energy

0 Pending Grant Applications with

Experience

15 years as a Design and Manufacturing Engineer which includes the product, the manufacturing processes and the manufacturing facilities for Textron, Alcoa and Union Carbide.

Specialized Professional Comnetence

Familiar with the safety, risk and liability aspects of products, manufacturing processes and manufacturing facilities as well as EPA and OSHA regulations.

Advanced engineering of industrial W A C systems particularly the energy and environmental aspects of ventilated work chambers. Engineering of all types of air pollution systems.

Engineering of all types of material handling and storage systems both bulk and unit. Designer of special purpose production machines. Design of process tank systems, spray booths, plastic bead stripping booths, wing and spar aluminum chip pneumatic collection systems and clean rooms.

Designer of hazardous waste reduction systems for solid, liquid and gaseous wastes and hazardous waste containment.

Management: Activities including problem or project definition, assumption verification, stating scope, setting success/failure criteria, subdividing project into tasks, assigning tasks, budgeting and scheduling.

William H. White

Professional Background

BS, Industrial Design, Syracuse University, 195 1 Paint Technology - Corrosion of Metals, Newark College of Engineering Professional Engineer - New Jersey, New York & Ohio Secretary of Committee #33 on Finishing Processes with the National Fire Protection Association Member of National Society of Professional Engineers Member of Ohio Society of Professional Engineers Member of Toledo Society of Professional Engineers Member of Society of Manufacturing Engineers - Association for Finishing Processes

Experience

35 years of experience in paint finishing systems which encompasses tens of thousands of paint booth, oven and spray equipment installations with the DeVilbiss Company, a leading supplier of finishing systems. These were new and renovation installations with values from $3,000 to $5,000,000.

Specialized - Professional Competence

Expert forensic engineer

Development and maintenance of finishing system standards, procedures and codes including the coating and coating application.

Management, supervision, design, specifications, fabrication, installation and code compliance of all aspects of manual and automatic finishing systems for general industry and the aircraft and automotive industries.

Conduct seminars on finishing systems and finishing system issues for govern- ment agencies, universities, trade associations and specific industrial firms.

Design of combination facilities which alternate functions cyclically from spray booth to oven and back again.

Conducted Paint Hanger design survey in 1987 along with 5 other technical specialists. This survey included 6 on-site evaluations at sites thoughout the U.S. and telephone surveys of the design parameters of 15 other Paint Hangers. This work was done on behalf the Air Force for a proposed Paint Hanger.

Documents

Mobile Zone - Optimized Spray Booth Control System For ... · Mobile Zone Designs into industrial facilities can be almost routine; enclosed is a Sverdrup brochure. I hope both of