MXPA97002201A - System of filtration and automatic air drying for water paint and coatings industry - Google Patents

Abstract

The present invention relates to a method for drying a water-based paint that was applied on a substrate to a surface thickness from about 0.00254 mm to 0.381 mm (0.1 to 15 mils) to provide a substrate having a substantially free painted surface of tackiness, capable of resisting the formation of surface cracks, which method comprises: (1) making air flow substantially uniformly in an angular and / or parallel direction and at a surface velocity of at least 3048 m / min (10 feet / min. ) above the painted substrate surface, while the painted substrate is maintained in a dry environment having a relative humidity RH in the range of about 25 to about 95 percent, and a temperature in the range of about 7.22 ° C to about 51.67 ° C (45 ° F to 125 ° F), and (2) continue with the procedure of step (1) in a continuous or dosed mode until the Substrate surface painted free of stickiness and free of physical defects after normal handling procedures

Description

AUTOMATED AIR FILTRATION AND DRYING SYSTEM FOR WATER PAINT AND INDUSTRIAL COATINGS DESCRIPTION OF THE INVENTION. The present application is a continuation in part of the copending application Serial No. 08/423683, filed on April 18, 1995, which is a continuation in part of the abandoned application 08/126547, filed on September 24, 1993. present invention relates to industrial coating systems and more particularly to an automated air filtration and drying system that is adapted to drastically reduce drying / curing times, normally experienced in manufacturing coating processes by directing a continuously filtered and de-humidified flow of recycled air on a coated product. An air atomizing spray gun is typically used to quickly apply paints, industrial coatings and other finished products to a wide variety of industrial, commercial and consumer goods. Unfortunately, during the application process, a large number of airborne particles and associated fumes called generally overcompounded are produced; To reduce potentially serious health risks associated with inhalation and body contact with overproduction, clothing and other protective systems are used, which have been designed in accordance with multiple strict regulations established by Occupational Safety and Health Administration (OSHA), Environmental Protection Agency (EPA), National Fire Protestion Association (NFPA), and other government agencies, to collect and effectively treat discharged air and direct it away from spray equipment operators and other personnel in the vicinity. For this, high-volume fans have been used to bring uncontaminated ambient air through the work area, where the air mixes with the over-casting, and then, the air now contaminated with coating particles and gases is carried into a duct. harmful, to a treatment area before downloading it. A dry filtration system, using retaining pads, has been commonly used to remove over-casting from the contaminated air stream, when the contaminated air stream passes through a retention cushion, the larger coating particles collide with it. the surface of the pad and adhere; as is known in the art, the surfaces of the pad can be covered with an adhesive to facilitate the capture of the particles, thus increasing the efficiency of pad capture; The proper functioning of the pads to remove particles from a contaminated stream depends on frequent inspection and regular maintenance. If the required inspections and maintenance are not performed according to the specifications, a blow of the pad and an accidental discharge of contaminants into the environment may occur. A water-based over-casting collector system, called a water drop system, uses a water cascade to remove the particles from the overrun from a collector wall. Contaminated water is temporarily stored in a collection tank and then pumped through a filter to remove suspended particles. The filtered water can be reused in the system or it can be discharged to a water treatment system, or to the environment. Before any discharge, the water must normally go through an expensive and time-consuming neutralization process, where the remaining particles in the water are allowed to sink into the collecting tank forming a concentrated layer that must be removed and thrown regularly. The described spray collector systems are moderately effective in removing large particles from the collection area of the spray booth, but they are not effective in collecting submicron size particles, and gases that are eventually discharged to the outside environment, potentially creating an environmental hazard.

Solvent-based coatings have been used in the finishing processes due to their fast drying characteristics. When the solvents evaporate, the suspended coating solids flow together and form a continuous layer of dry solids. An important disadvantage of these coatings is the danger of explosion caused by the inherent capacity of inflammation of the solvent and of the sumos that are released during the evaporation process. Additionally, the high solvents discharged into the atmosphere establish an environmental hazard due to the interaction of solvents with the ozone layer. As such, alternative coating processes using solid dry powders, solids, and solids carried in water, have been developed to avoid the disadvantages associated with solvent based coatings. In a dry powder coating process, an electrostatic spray gun assembly having a positive polarity is used to apply dry powder solids to a product having a negative polarity. Due to the mutual attraction resulting from the positively charged paint particles, and the negatively charged product, overrooting is greatly reduced. After receiving the dried paint particles, the coated product is baked at an elevated temperature, until the dried paint particles melt and flow around the product, thus forming a continuous coating. Such systems require a substantial investment for the equipment and have a limited use due in part to the required baking stage. Solids coating systems use a high viscous paint emulsion that has a high proportion of solids to the solvent, as a result, the paint emulsion is generally applied to the product with a high pressure nozzle that naturally produces a significant increase in overrun. The coated product is subsequently cured in a separate drying area using a heat source such as an oven or heat lamps. As in the other systems, the system of coating with high solids requires an important investment for the equipment and has a limited use due to the necessary step of the heating. In a wet system of water borne solids, the coating solids are suspended in a fluid having a relatively high proportion of water to the solvent. Although the equipment required for this type of coating is generally less expensive and complex, due to the low temperature of curing, the drying and curing times are much longer than with coatings based on dry powder or solvent.

As mentioned, the available collector systems are generally designed to discharge large amounts of air to the outside environment; this results in high energy costs, since extra must be spent to recondition the air inside the building. In addition, the residual pollutants in the discharged air are strictly regulated by the governmental agencies, frequently requiring the obtaining of a plurality of expensive permits or the payment of high fines; These energy requirements and regulations greatly increase the cost of the finished product. In the last decade, the use of solvent-based coatings has drastically decreased due to the growing number of restrictions on the emission levels of polluted air to the environment, as such, the popularity of dry powders, solids carried in water and other alternatives, They have increased a lot. Due to the high cost of the investment and the limitations of coatings with dry powder and high solids, water-based coatings seem to be the best alternative for economical use. As mentioned, one of the disadvantages of the system carried in water is the long drying cycle, which results in high production costs. In order to avoid the disadvantages of the prior art, the present invention provides an automated air filtration and drying system for products coated with a water-based coating. The present invention provides a cabin coupled to a drying and filtration module, through an interface wall. The drying and filtering module can be used to filter the overrun during a coating operation or to provide recycled air that is filtered and dried to accelerate the drying process, or both. Additionally, the present invention incorporates an environmental management system and the energy to control, regulate and supervise the operation and operation of the filtration and drying system, a capture apparatus for capturing and controlling iron phosphating particles, carried by air, coatings carried by water, garbage and other particles in the air, and a control, drying module to quickly dry a painted article, using a continuously filtered and dehumidified flow of recycled air.

Advantageously, the air filtration and drying system of the present invention is adapted to drastically reduce the drying time in coating processes, regulate and automatically control the application and emission of industrial coatings and waterborne paint, and basically reduce energy operating costs. The environmental management system and energy, is an automated management and control system that is adapted to bring the operation of the capture device and the drying module to an optimal state, but keeping the system's energy consumption to a minimum Filtration and air drying. In a typical application, the energy and environment management system includes a computer, a plurality of interference panels, peripherals, a plurality of input and output interfaces and a number of sensors to adjust and measure a wide variety of conditions. through the filtration and drying system, and in the spray booth. Examples of the above conditions are the following: a) velocity of the front of the collecting area b) static pressure of filtration in the first stage c) static pressure of the main filtration d) ambient temperature e) humidity of the environment f) humidity induced g ) actual elapsed time h) electrical service status (voltage, amperage, polarity) i) amperage taking by the motor j) counting of the prefiltration particles k) counting of the postfiltration particles 1) prefiltration gaseous phase m) gaseous phase postfiltration n) volatile organic compounds (presence, penetration) The capture apparatus of the present invention, is adapted to remove contaminants from overrooting from the air inside a spray booth, thereby eliminating virtually the release of harmful contaminants in the atmosphere and in the environment that surrounds the work. Preferably, the capture apparatus is designed to provide a minimum air flow of 100 feet per minute, through the collector cross-sectional area of the spray booth, and a capture wall capacity of 10,000 to 100,000 CFM a 1. 5 to 3. 0"WG The capture apparatus is equipped with a fan such as a fan with backward inclined blades to propel contaminated air from the collection area of the cabin to a multi-stage dry filtration system, in where the filtered air, or is expelled to adjacent work areas during a paint or regeneration cycle or is returned to the collection area during a drying cycle, under the control of a computer controlled derailleur system. and energy, includes a process control system to optimize the operation of the capture device by controlling the operation of the fan motor. process control, incorporates a feedback duct for the motor amps and a variable frequency drive system, such as an ACS 500 drive system, manufactured by ABB Industrial Systems, Inc., to regulate the speed in RPM, fan motor, compensating the static pressure increased by the filtering load. As a result, the present invention automatically provides constant regulation of the volume of air flow and the frontal velocity independently of the air load, thus reducing the time of drying and curing; any increase in current intensity of 5%, or higher than the pre-established conditions, is detected by the process control system, and results in initiation of a self-diagnostic subroutine, the production of a data input from registration, for future analysis and the generation of a pre-programmed service request. The multi-stage dry filtration system incorporates a plurality of filtering system arranged in parallel, each of the systems having a plurality of dry type filters, arranged in a row. This highly efficient series arrangement of filtering components includes retaining pads, primary and secondary pre-filters, a high-efficiency main filter, and a gas-phase filter that absorbs odor. Detailed descriptions of the filter components used in the preferred embodiment of the present invention are indicated in the following paragraph. The retaining pads are formed of a polyfiber synthetic material or have a multilayer construction, and have a cut and expanded water resistant layer with multiple lid damping openings, and two individual double density synthetic bakes. The secondary prefilters are constructed of a folded medium enclosed in a water-resistant cardboard structure, and have a nominal efficiency of 25 to 60% (retention), in an ASHRAE TEST 52-76 Dust Spot test, for the dust that is established by the American Society of Engineers for Heating, Refrigeration and Air Conditioning, which is a measure of the ability of a filter to reduce the grime of both the fabrics and the interior surface of the building. Similarly, the primary pre-filter is formed of a folding medium of ASHRAE, by 35 to 75%, enclosed in a water-resistant cardboard structure. The main filter includes a high deficiency folding medium or, a high efficiency particulate air filter, hereinafter referred to as HEPA, which has 90 to 99%, particle efficiency of 0. 3 microns, and an efficiency of penetration of no more than 10%, in particulate of 0. 3 microns, according to test B53928 / M 7605, of the ASHRAE sodium flame method.

Finally, the odor absorbing gas phase filter that provides gas control at 0.0003 microns in size employs coarse fiber substrates, with a porous retention structure of 80%, in a medium of cross-linked coal, where one foot Cubic substrate provides approximately 2 million square feet of surface area for adsorption. As is obvious, for any technician, many other filtering components may be used in place of those described without departing from the scope of the present invention.

The drying and filtering module can be configured to include intake or exhaust ventilation and exhaust or return ventilation in a single interface wall. This configuration provides a simple means to attach the module to a drying cabinet; it also allows a regular recirculation of the air in the drying cabinet. In addition, with this configuration, the drying cabinet can maintain its temperature and humidity levels even with an opposite open wall of the interface wall, between the intake and outlet ventilation, there is an airflow recycling system that includes a step that it takes out the filtered air and takes it to the outside work during a painting cycle and the filtered dry air returns during the drying cycle. Various types of filtered drying modules can be incorporated into the present invention, as the case requires. A first type can incorporate a twin regenerative tower dryer, a continuous rotary air dryer, a continuous rotary air dryer or a multiple liquid separator or dryer unit. This type of curing drying module is adapted to direct a continuously heated and de-humid recycled flow through a coated product to absorb and remove moisture. A second type may incorporate a dehumidification system based on cooling, this type of system recirculates air that cools down from its dew point to give moisture that condenses on a nearby surface.

Advantageously, in any type of system, the pollutant concentration and the humidity of the recycled air fall continuously as it is cycled on the coated product, by the capture apparatus and by the drying and curing module. In applications that require continuous operation and drying agents, the regeneration of the medium occurs when the system is working weakly or is stopped, on the contrary, the refrigerant dryers are adapted to operate continuously and do not require a regenerative stage. In a first embodiment of the present invention, a twin tower dryer is used to heat and dehumidify the spray booth during the drying process. As is known, a recjenerative twin tower dryer uses a pair of adsorption columns in an alternative manner, allowing one column to be used while the other is regenerated. The geometry, size and configuration of the secant fact of that system is carefully adjusted according to specific application criteria, such as adsorption capacity, wet air velocity, retention time, operating cycle, drying efficiency, consumption of energy, cure rate and the like; In addition, the minimum and maximum operating parameters are specifically assigned to accommodate specific functional variables, such as the rate of generation of the medium, meteorological conditions and operation of the spraying equipment.

In a second embodiment of the present invention, a dehumidifying unit based on cooling cooling is used to cool and dehumidify the air in the spray booth during the drying process. As mentioned, the recirculated air that is cooled below its dew point, produces moisture that condenses on the closest surface it finds, thus the air in the system dehumidifies during the cooling and condensation cycle. The cooling and cooling unit may comprise, 1) an evaporator or cooling coil, 2) a compressor, 3) a superheat condenser or coil, 4) a liquid refrigerant and a receiver tank, 5) an expansion tank, 6) a remote condenser, 7) a Humidifier .. The superheat coil and a remote condenser, provide that the air temperature in the system, can be regulated exactly without turning the system off and on. The humidifier allows the system to regulate the relative humidity of the air. This method can be used to pretreat the surface of the product (for example, removing the moisture before applying a coating carried in water); and / or a post-treatment of the surface of the product (that is to remove the application after the application of coating carried in water). In addition, by providing a drying / curing module, which does not incorporate a heating system, this method has the advantage of being more easily adjusted to fire safety regulations; for example, both NFPA and OSHA have regulations regarding the use of heat or hot surfaces in or near a spray booth (see for example OSHA 1919. 107 and NFPA 33). This modality thus provides an effective means to dry offering a safe environment. BRIEF DESCRIPTION OF THE DRAWINGS. These and other features of the present invention will become more apparent from the following detailed description made with reference to the drawings, in which: FIGURE 1 illustrates the trajectory of the air flow in the painting cycle, through a automated air filtering and drying system, according to a second embodiment of the present invention; FIGURE 2 illustrates an automated air filtration and drying system for a spray booth according to a first embodiment of the invention; FIGURE 3 illustrates the trajectory of air flow in the painting cycle through the automated air filtration and drying system of Fig. 2; FIGURE 4 illustrates the trajectory of the air flow during the drying flow through the system of FIG. 2; FIGURE 5 illustrates the formation of an overrun impact template on the collector face of an overprocessing filtration system according to the prior art; FIGURE 6 is a top view of a quadrant diffusion system according to the present invention; FIGURE 7 is a front elevational view of the system of FIG. 6; FIGURE 8 is a front view of the quadrant diffusion system with the front and rear panels mutually centered; FIGURE 9 is a front view of the quadrant diffusion system with the rear panel displaced in a negative direction along the x, y axes; FIGURE 10 illustrates a specific application of the quadrant diffusion system in the automated system of Figs. 1, 2; FIGURE 11 is a block diagram of the energy and environmental management system; FIGURE 12 is a bar graph comparing the drying times for a product entering and leaving a cabin constructed in accordance with this invention; FIGURE 13 is a bar graph comparing drying times for a product entering and leaving a cab constructed in accordance with this invention; FIGURE 14 is a bar graph comparing the drying times for a product entering and leaving a cabin constructed in accordance with this invention; FIGURE 15 is a bar graph comparing the drying times for a product entering and leaving a cabin constructed in accordance with the invention; FIGURE 16 illustrates an automated air filtering and drying system for a drying and spray booth incorporating a horizontally mounted impeller fan according to the invention; FIGURE 17 illustrates an automated air filtration and drying system incorporating a remote condenser and a drying cabinet with an open wall according to this invention; FIGURE 18 illustrates the control components of the humidity temperature according to this invention. Referring now specifically to the drawings according to the present invention, there is illustrated a first embodiment and a second one, of an automated filtration and drying system generally designated as 10, wherein, the like reference numbers refer to equal parts in the drawings. As illustrated in FIG. 2, the automated filtration and drying system 10 is adapted to be used in conjunction with a spray booth 12, removing any overrun produced when coating a product 14, with a spray gun 16., or another suitable applicator. Referring to Figs. 1-4, the contaminated air is taken to a capture apparatus 19, within the system 10, as indicated by the directional arrows 18, by means of a fan 20, with tilted blades and a fan motor 22. computer-regulated current feedback conduit for the motor, including a pair of sensors 24, 26, of static first-stage pressure, a pair of static pressure sensors of the main filter 28, 30, a sensor 32, of the amperage / RPM , of the motor and a variable frequency driving or driving system 34, controlled by computer, is provided to regulate the speed of the motor 22, compensating the static pressure caused by the filtering load and also variations in the supplied voltage.

As indicated in Fig. 3, the outputs of the static pressure sensors 24, 26, 28, 30, and the output of the intensity and speed sensor 32, are brought to a computer system 36, through an assembly 38, peripheral interface panel. In response to this, the computer 36 provides the appropriate speed compensation signal to the variable frequency system 34, again through the peripheral interface panel assembly 38. More specifically, as the total differential static pressure between the pair of static pressure sensors of the first stage 24, 26, and the pair of static pressure sensors 28, 30, of the main filter increases due to the accumulation of the filtrate, which determines by the computer 36, the speed of the motor 22, increases by means of the variable frequency system 24, offering a constant volume of air flow, which is predetermined according to the specific case as well as the flow velocity through the capture apparatus 19. In a similar manner the speed of the motor 22 of the The fan is modified according to the variations in the voltage to provide again the volume and the required constant velocity of the air flow. The engine speed can be adjusted in a continuous manner or in response to predetermined variations in static pressure levels. The static pressure sensors 24, 26, 28, 30 preferably comprise a Pitot tube having a closed end and a plurality of radial holes disposed near a static pressure tip, where the holes are presented to a stream of air at a 90 degree angle, thus providing accurate reading of the static pressure. the tip of the static pressure is connected by means of a flexible tube to a transducer or other pressure indicating device that is adapted to provide a 4-20mA signal to a computer 36 through the peripheral interface panel assembly 38. Again referring to Figures 1-4, contaminants from the overrun are captured and removed from the inlet stream of contaminated air 19 as it passes through the capture apparatus 19. More specifically as indicated by the directional arrows, the fan impeller 20 is used to bringing contaminated air from the spray booth through a dry multi-stage filtration system, comprising an array of retaining pads 40, a secondary pre-filter arrangement 42, a primary pre-filter 44, a HEPA main filter, a 46 filter and a Gas separation filter 48. After passing through the multi-stage filtration system, the filtered air is expelled This is done at the workplace via a discharge port 50 of the paint cycle, or passes through a dehumidification module 52, and returns to the spray booth 12 through an air outlet of the drying cycle 54. As illustrated in Figures 1-4, a diverter 56 that preferably includes an electric motor and associated links, is used to regulate the position of the diverter or damper 58 by the control of the computer 36, selecting the direction of the filtered air through the discharge port 50 of the paint cycle or dehumidification system 52. As said, the dehumidification system 52 may comprise either a heat-based system (Figures 2-4) or a refrigeration-based system (Fig. ) The invention as shown in Figures 1-4 and 16, has the further advantage of providing automated filtration and drying 10 which are easily mounted to a drying cabinet 12. These modalities only require a single wall of interface between the drying cabinet 12 and the system 10. Thus, the design, manufacture and use of the drying cabinet improve greatly. In addition, the interface wall can be composed of filtering devices 40, 42 and 64 and of a return duct 54. Therefore, unlike other systems, these modes do not require underground equipment or equipment on the roof. Referring now to figures 2-4, the first modality, which incorporates a system based on heat, is illustrated. This system preferably uses a regenerative twin tower dryer including hydro absorber banks 60, a regenerator assembly 62 and a computer controlled heating element 63, which may be separate or integrated with the regenerator assembly 62. The air flow path of the paint cycle of the present invention is illustrated in FIG. 3. According to the directional arrows 18, the air, which has been contaminated by the over-casting, is brought to the system 10 for drying and filtering atomized air, by the fan 20 and it then passes through the pad retention arrangement 40, the secondary prefilter array 42 and a quadrant diffusion system 64. After advancing beyond a sensor array area 66, the partially filtered air passes through the primary prefilter 44, the high efficiency main filter (HEPA) 46, the gas separation filter 48 and the drive fan 20. during and In the painting cycle, the diverter door 58 is fixed on the outlet 68 of the dehumidifier system 52, and the filtered air is directed to the workplace by the discharge port of the paint cycle. Referring to FIG. 16, an additional embodiment is shown, this embodiment is essentially the same as that shown in FIGS. 1-4, except that the fan 200 (20 of FIGS. 1-4) is mounted horizontally on the rear wall in FIG. vertically in the ceiling. It is considered that a drying / curing system is used, either refrigerant or heat-based. As is evident from the comparison of the figures 3 and 4, the initial portions of the drying cycle and the air flow in the painting cycle are identical in their trajectories properly referring specifically to FIG. 4, the air in the spray booth is carried by the fan 20 through the arrangement of retaining pads 40, second prefilter array 42, diffusion system 64, sensor area 66, primary prefilter 44, HEPA main filter 46 and gas separation filter 48. Unlike path of paint, the filtered air is directed to the drying and curing module 52, during the drying cycle after passing through the fan 20. more specifically during the drying cycle, the diverter door 58 is fixed on the discharge port of the paint cycle 50, and the filtered air is conducted to the dehumidification system 52 through the inlet 68. After flowing through the hydroabsorbent banks 60, the regenerative assembly or assembly 6 2 and the computer controlled heating element 63 of the dehumidifying system, the already filtered, hot and dehumidified air leaves the dehumidifying system through the outlet 54 of the drying cycle and passes to the spray booth. Then the filtered, hot and dehumidified air passes over a coated product that is dried inside the spray booth to absorb more and remove its moisture, before being taken back to the filtration and drying system 10 by the fan 20. Advantageously , the air in the spray booth is filtered, dehumidified and heated continuously as it is recycled through the multi-stage system 52, drastically reducing the drying time required by water-based coatings. Referring now to FIG. 1, a second embodiment with a cooling-based system is illustrated. The system is functionally e? Juivalent to the first modality with the exception of the components located within the dehumidifying system 52. The air filtering mechanisms are equivalent in both modalities. Thus, the two modes will only work differently when the diverter door 58 is closed and the air is flowed into the dehumidification system 52. (See Figures 1 and 4). in this second embodiment the hydroabsorber bank 60, the regenerative assembly and the computer controlled heating element 63 of the first embodiment (Fig 2-4) have been removed. Instead, the present system uses components that may include a compressor 71 a liquid cooler or receiver tank 73, an expansion valve 75 a reheat condenser or coil 77, an evaporator or cooling coil 79 and a drain 81. As it has been noted, when the door of the damper 58 is closed, the air is forced into the dehumidification system 52. The air that is subjected to the cooling system is cooled down from its dew point to give moisture in the form of condensate in The closest surface you find, the drier air is passed back to the spray booth by way of outlet 54, where it acts like a sponge absorbing the moisture produced. The components forming the cooling system are typical of the present technique. Referring now to fig 17. a drying / filtration system including a remote condenser 83 and a humidifier 91 is presented. The remote condenser 83 includes a condenser coil 87 and a cooling fan 85. The operation of the remote condenser 83 and of the humifier is further detailed in Figure 18, it presents a dehumidification system 52 for maintaining a predetermined temperature and humidity that can be located within the drying / filtration module, the humid air 212 enters the enclosed passage 220 and is cooled by the evaporator 79. In addition to cooling the evaporator removes moisture from the air to produce dry cold air 214. the humidity of the evaporator 79 is then drained, what is not shown. After the air is cooled, it passes through a reheating coil 77 that produces hot dry air 216. It can return to the drying cabinet to collect moisture from a wet coated surface. The compressor 271 moves the system by pumping a cooling fluid 210 to the evaporator 79. Due to the process the refrigerant is heated, the heating coil can be used to reheat the cold air to a suitable temperature. However if the refrigerant becomes too hot a solenoid valve 22 can be used to redirect the refrigerant to the remote condenser 87, which cools and condenses the refrigerant, the remote condenser 87 is located on the outside of the drying / filtering system so that Any undesirable heat can be removed from the system and expelled to the work environment. A fan 85 can be used to further improve the cooling effect of the remote condenser 87. The air temperature can be regulated by a PLC thermostat or a similar device, which is not shown. Based on a pre-set temperature, the solenoid 222 will decide whether or not to send the refrigerant to the heating coil 77 or the remote condenser 87. Since the air is constantly being circulated in the system, the humidity is continuously decreasing. A humidifier 91 can be used to introduce moisture back into the system when it is needed to control the humidity in the system, any moisture detection device can be used to set the humidity level. Thus, these components allow the user to control the environmental drying by selecting the exact temperature and humidity. Since different types of paint require different drying conditions, such control is critical to obtain a general drying efficiency. With the components presented, this system can easily provide a temperature within the range of 45 to 125 ° F or 6 to 54 ° C and a relative humidity (RH) in the range of 25 to 95%. Selecting a particular system establishment for example 50"F = 10 ° C 45% RH) will depend on several factors including the thickness of the paint and the type of paint, although this system is supposed to accelerate drying for almost any paint based on water with a coating thickness of 0. 1 to 15 millimeters, the invention is not limited to such applications.It is also assumed that operation outside the mentioned ranges can be achieved with relatively simple modifications of the drying / filtering system. Figures 1-4 and 11, a volatile organic compound (VOC) passes through the sensor 70 and is used to detect the presence of vapors of organic solvent or other volatile or dangerous vapors.The passage of the VOV by the sensor 70 includes a sensor element, preferably one having steam-sensitive conductivity or the like, which is adapted to transmit a 4-20 mA signal to computer 36 by means of assembly e peripheral interface panel 38. If the computer 36 determines that there are dangerous vapors in the system during painting or drying, in response to the output of the sensor with VOC step 70. will trigger the appropriate visual or auditory alarms to warn personnel that a dangerous compound is in the system and that immediate service is required, perhaps due to malfunction or improper installation of the gas separation filter 48. The output of the VOV 70 passage sensor is further used to control the operation of the diverter actuator 56 and the dehumidifier system 52, and the associated position of the door 58. More specifically in response to a positive reading of the sensor 70 (VOC present) the host computer 36 sends a signal to remove the drying cycle by means of the interphase panel assembly peripheral 38 to an interlock of the drying system 72, comprising an electromechanical relay or something similar, which results in the quenching of the dehumidifier system 52 and the fixing of the door 58 on the inlet or intake 68 of the dehumidifying system 52 by the diverter or damper actuator 56. Likewise, when a VOC is not detected, the sensor 70 sends a negative reading to the interlock 72, thereby enabling the door of the diverter 58 and allowing the initiation or continuation of a drying cycle. Advantageously, the duration of operation of the secant within the hydro absorber banks 60 (Figures 2-4) greatly increases by preventing the contaminated air VOC from entering the dehumidifier system 52. A humidity outlet sensor 74 and the ambient humidity sensor 76 are used to direct and control the operation of the dehumidifier system 52. The humidity and humidity outlet sensors in the environment 74, 76 preferably include a moisture sensitive element, having an AC resistance that responds to moisture, and a thermistor that is adapted to compensate for the temperature dependence of the temperature sensing element. Each humidity sensor provides a 4-20mA signal that is supplied to the host computer 36 through the peripheral interface panel assembly 38. During the drying cycle, the outputs of the sensors 74, 76, provide the host computer 36 with the data corresponding to the humidity of the air that is flowing out of the dehumidifying system 52 and enters the capture apparatus 19, respectively. When the humidity level measured by one or both of the sensors falls below a predetermined limit value, indicating that the coated product inside the spray booth 12 (Fig 2) has dried / cured to a sufficient degree, the cycle of drying is suspended by the interlocking system 72, and the door 58 is then fixed on the inlet or outlet 68 of the dehumidifying system 52. Correspondingly the drying cycle is enabled as long as the measured humidity level remains above the humidity limit default during the drying cycle. Similarly, if the moisture level fails to reach the moisture limit of the drying cycle after a certain time, which would indicate a malfunction of the system, the drying cycle is disabled. The present invention incorporates the ambient temperature and outlet sensors 78, 80 to provide the computer 36 with outward and ambient flow temperature measurements, respectively. Preferably each temperature sensor includes a thermistor and a respective circuit for supplying 4-20mA signal to the host computer 36 through the peripheral interface panel assembly 38. If the outward and / or environmental temperature measurements deviate sufficiently from an optimum drying temperature, predetermined for the specific application during the drying cycle, the computer 36 transmits the necessary signal of temperature adjustment to a temperature controller 82, which subsequently provides the appropriate temperature adjustment signal to the heating element 63 controlled by the computer (Fig 2-4) or the cooling system (Fig 1) located within the dehumidifying system 52. The sensor area 66 includes an Air Flow Sensor 84, for measuring the inflow of air into feet Cubic per minute (-CFM) and an air velocity sensor 86 to measure the velocity of the air entering feet per minute (FPM), where the s sensor outputs are supplied to the host computer 36 by means of the peripheral interface panel assembly 38. Preferably the airflow sensor 84 and the air speed sensor 86 include a self-sensing tube assembly similar in construction to the static pressure sensors already described 24, 26, 28 and 30, although any appropriate sensor technology can be used. The data obtained by sensors 84 and 86 are used mainly for guidance purposes. However, since the air flow and the velocity of the air are directly related to the degree of charge in the filter, the outputs of the sensors 84, 86 can be used by the host computer 36 instead of or in conjunction with the outputs of the static pressure sensors 24, 26, 28 30 to thereby control the speed of the fan motor 22 by means of the variable frequency drive system 24. The particle sensors 88, 90 of the type known in the art are used to provide the computer 36 with measurements of the upstream (unfiltered) and downstream (filtrate) particle concentrations, respectively. If the particle concentrations deviate from the expected values, or if the decontamination efficiency of the capture apparatus 19 falls below a predetermined minimum level value, the computer 36 is adapted to send the necessary status information to the operating system. Referring to Fig 11 (and 2), it is illustrated, in a partial block form of the environment and energy management system according to the present invention. As said before the environmental and energy management system includes a host computer 36 for directing and controlling the operation of the automated air drying and filtration system 10, a peripheral interface panel assembly or assembly 38 is used to direct the system information received from the numerous sensors arranged within the spray booth 12, the capture apparatus 19 and the dehumidifier system 52 to the computer 36 and for issuing any control information required for the system components properly operated / controlled by the computer.

A display 92 is used to provide the operator with a visual indication of some or all of the data read by the sensors and received by the computer 36, allowing the operator to direct the operational status of the automated air filtration and drying system of this invention. Preferably a datalog of the received sensor readings is stored for future analysis on a memory system 93 such as a hard disk or the like. The environmental and energy management system includes an operator control panel for controlling the basic operation of the air filtration and drying system, wherein the fan motor 22 and the system controls are activated or deactivated by a manual action on the buttons 96 and 98, respectively, and the drying cycle is activated or deactivated by the buttons 100 and 102 of drying and painting, respectively. The operator control panel 94 further includes a plurality of highly visible, multi-color status lights 104 which are adapted to provide the operator of the system with information about the state of the static pressure, the number of engine revolutions, the air flow, air velocity, outlet temperature, ambient temperature, exit humidity, ambient humidity, presence of VOC, concentration of particles and the like. Preferably, a green light is used to indicate normal operation of the system within the set margins, a yellow light is used to indicate that the system is approaching states that need diagnosis or maintenance, and a flashing red light is used to indicate poorly operation and shutdown of the system or the need for immediate maintenance or repair of the system. A keypad 106 is provided on panel 94 of the operator control for data analysis, record keeping and specific functional or application program with aggregates or modifications, such as the outlet temperature and humidity requirements, motor speeds of the fan and the like.

Referring now to FIG. 5, the air flow through the collector face 108, of the normally available dew point filtration systems, frequently produces an unbalanced impact template 110, on the collector face 108, when the dew envelope it is taken to the filtration system after passing around passing through, from the collecting layer 108, it begins to cover itself, preventing the air from passing through, the periphery of the impact template 110, migrating outwards as indicated by the directional arrows 114. To prevent the formation of such an unbalanced dew impact template, the present invention provides a new quadrant diffusion system 64, to produce a balanced flow of air through the collecting face of the drying and filtration system of automated air 10. As previously described with respect to Figs 1 and 3-4, the diffusion system 64 is preferably arranged behind the arrangement of tension pad 40, and a secondary prefilter arrangement 42. As illustrated in Figs. 6, 10, system 64, includes at least one pair of overlapping parallel panels 116, 118, each including a patterned series of openings where the template or pattern of openings in each panel offers minimal restriction to airflow , although the front panel 116, and 118 includes the same number of openings, the openings in the rear panel incorporate a slightly larger center in the center template. As such, the center of nominal air flow through the panels 116, 118 ,. it can be altered by moving the panels 116, 118, slightly away from the center of the one with respect to another, as illustrated in Fig. 7. Preferably, the front panel 116, remains stationary and the rear panel 118, is displaced as necessary as along the X, Y axes, to provide the required center of air flow. For example, as shown in Fig. 8, the nominal air flow center, is presented in the opening 120, when the panels 116, 118, are mutually centered. If the rear panel 118 moves in a negative direction along the X, Y axes, as shown in Fig. 9, the nominal air flow center moves to the upper right region of the panel arrangement. As evidently seen, the nominal flow center through the parallel panels can be moved as necessary according to the specific application requirements by altering the relative orientation of the front and rear panels 116, 118. An application of the diffusion system quadrant 64, incorporates nine pairs of overlapping parallel panels to balance the flow on the collector face (retention pad arrangement 40), of system 10, as illustrated in Fig. 10. More specifically, nine pairs of parallel panels 116, 118, are arranged in a three-by-three array, behind the retention pad arrangement 40, and the secondary pre-filtering array 42, with the nominal air flow center through each pair of panels 116, 118, adjusted for provide the airflow template indicated by the directional arrows 124. Advantageously, the resulting template produced as the coating product 14 , it is evenly distributed over the entire collecting area, of the arrangement 40, due to the balanced air flow provided by the quadrant diffusion system 64. Referring now to Figs. 12, 15, various bar graphs are shown comparing the drying times of a product inside and outside a cabin constructed in accordance with this invention. In each of the graphs represented in these figures, the clear bars represent the drying time, where the cabin is used and the crossed bars represent the drying times when the cabin is not used. Fig. 12, which shows the drying time of a round cast with a humidity of 4-5 MILS, shows that only 12. 5 minutes are needed for a casting to dry completely when placed in the cabin in opposite position at 69 minutes of when it is not put in the cabin. Fig. 13, which shows the drying time of a round casting of 4-6MILLS, with a fan blowing on the casting, shows that it only takes 11.5 minutes for a cast to dry completely when placed in the cabin, against position at 69 minutes of when it is not put in the cabin. Fig. 14, which shows the drying time for an assembled pump (2, 800 pounds), with 6-8 MILLS, shows that only 42. 5 minutes are needed, for the pump to dry completely when placed in the cabin in against position to 123 minutes of when it is not placed in the cabin. Fig. 15, showing the drying time for an assembled pump, 2, 800 pounds with 3. 5-5 MILLS, shows that only 16 minutes is needed for the pump to dry completely in the cabin as opposed to the 90 minutes of when it is not placed in the cabin. As a result of the improvements described above in the temperature and humidity control system using a separate condenser and a humidifier component, means are provided to achieve more control over the drying by having the capacity to establish the required temperature and RH. These characteristics of temperature control and RH, (relative humidity), have been found to be particularly important in affecting the drying of substrates treated with an aqueous paint in a wide range of drying and coarse characteristics. Based on these modifications, a method is provided for drying an aqueous paint, which is applied on a substrate in a surface thickness of about 0.0025cm to 0. 0375cm, to provide a substrate that has a painted surface essentially free of accumulations or plates and capable of resisting the formation of surface imperfections, which method comprises: (1) making the air flow substantially uniformly in an angular or parallel direction and with a surface speed of at least 3 meters. per minute, on the painted substrate surface, keeping it in a drying environment that has a relative humidity (RH), in the range of approximately 25 to 95%, and a temperature in the range of approximately 7 to 51 degrees , (2) continuing the procedure of step (1), in a continuous mode until the surface of the substrate is free of spots and plaques after normal treatment procedures. It should be recognized that the system and methods described are particularly effective in accelerating the drying of most waterborne paints, when the temperature is set between 65 and 80 degrees F, or 19 to 27 C, and the RH is established. from 25 to 45%. The above description of the preferred embodiments of the invention, has been presented for the purpose of facilitating illustration and description, is not intended to be limiting, because there are many variations and changes, obvious to the technician without leaving the spirit and scope of the present invention.

Claims (22)

1. CLAIMS 1. - A filtering and drying apparatus for drying a coated surface with a water borne coating, comprising: an interface wall having an exhaust vent and a return vent, the interface wall is connectable to a cabinet drying; an airflow recycling system that has an enclosed air passage that flows between the exhaust ventilation and the return ventilation; an air filtration system that includes at least one filter of the dry type, the filtration system is located within the air passage next to the exhaust ventilation; a dehumidifying system located inside the enclosed air passage.
2. 2. Apparatus according to claim 1, characterized in that the dehumidifying system includes an air cooling system.
3. 3. Apparatus according to claim 2, characterized in that the dehumidifying system includes a refrigerant fluid, a compressor, an evaporator and a reheat coil.
4. 4. The apparatus according to claim 3, characterized in that it comprises a remote condenser, which is located outside the enclosed air passage.
5. 5. Apparatus according to claim 4, characterized in that it comprises a humidifier, which is located within the enclosed air passage.
6. 6. - Apparatus according to claim 1, characterized in that, the dehumidifier system includes means for preselecting a temperature in a range between 7 ° and 51 ° C.
7. 7. Apparatus according to claim 1, characterized in that the dehumidifier system includes means for pre-selecting a relative humidity between 10 and 95%.
8. 8. - The apparatus according to claim 1, characterized in that, the filtration system includes a series of multiple stages of dry type filters.
9. 9. Apparatus according to claim 1, characterized in that, the air flow recycling system includes a fan mounted horizontally to move the air.
10. 10. - The apparatus according to claim 1, characterized in that, the air flow recycling system comprises a fan mounted vertically to move the air.
11. 11. A drying and filtering system for drying a coated surface with a water borne coating comprising: a drying cabinet, which includes an interface wall, adjacent side walls, and an open wall opposite the interface wall; and a drying / filtering module having: a first outer wall with a intake vent and an exhaust vent, being coupled to the interface wall of the drying cabinet; an air flow recycling system that has an enclosed air passage, where it flows between the intake ventilation and the exhaust ventilation; an air filtration system that includes a plurality of filters of the dry type, the filtration system is located within the enclosed air passage close to the intake ventilation; A dehumidifying system that includes an apparatus that varies the air temperature, the dehumidifying system, is located within the air passage enclosed near the exhaust ventilation.
12. 12. - The drying / filtration system, according to claim 11, characterized in that the dehumidifier system includes a refrigerant fluid, an evaporator, a compressor and a reheat coil.
13. 13. - The drying / filtration system, according to claim 12, characterized in that it comprises a remote condenser, being located outside the enclosed air passage and being connectable to operate in the dehumidifying system.
14. 14. System according to claim 11, characterized in that the dehumidifier system includes means for selecting the air temperature in the range between 7 ° and 51 ° C, in the drying cabinet.
15. 15. - The system according to claim 11, characterized in that the dehumidifier system includes means for selecting a relative humidity between 10 and 95% for the air in the drying cabinet.
16. 16. - A drying / filtering module comprising: a first outer wall having a intake ventilation and an exhaust ventilation; an air flow recycling system that has an enclosed air passage where it flows between the intake and outlet ventilation; an air filtration system located next to the intake vent where, the filtration system includes a plurality of filter systems arranged in parallel, each filtering system having a plurality of dry type filters, arranged in series; a dehumidifying system that includes an apparatus for varying the temperature of the air, the dehumidifying system being located within the enclosed air passage close to the exhaust ventilation.
17. 17. - A method for using recycled air to dry a coated product with a coating carried in water, the method comprises the steps of: enclosing the product in a drying cabinet; remove polluted damp air from the drying cabinet; filter the humid air contaminated by a series of filters of the dry type to produce a filtered humid air; dehumidify the filtered moist air to obtain filtered dry air; return the filtered dry air to the drying cabinet, where the filtered dry air can absorb moisture and contaminants from the coated product, with a coating or paint carried in water; repeat the previous steps, until the coated product, with the coating carried in water, is dry.
18. 18. - The method according to claim 17, characterized in that, the dehumidifying step has the steps of: cooling the filtered moist air with an evaporator thus removing the moisture to produce a filtered and cold dry air; as needed reheat the filtered and cold dry air by a reheat coil, to obtain hot filtered dry air; depending on whether it is necessary to cool the hot filtered dry air by means of a remote condenser.
19. 19. - Method according to claim 18, characterized in that the dehumidifying step further includes the step of controlling the humidity of the filtered dry air with a humidifier.
20. 20. - A method for drying an aqueous paint that is applied to a substrate, in a surface thickness of approximately 0.0025cm, at 0. 0375cm, to provide a substrate that has a substantially stain-free surface, capable of resisting the formation of surface imperfections, method comprising: (1) making the air flow basically uniformly in an angular or parallel direction and with a surface velocity of at least 3 meters. per minute, on the painted substrate surface, keeping it in a drying environment that has a relative humidity (RH), in the range of approximately 25 to 95%, and a temperature in the range of approximately 7 to 51 degrees , (2) continuing the procedure of step (1), in a continuous mode until the surface of the substrate is free of spots and plaques after normal treatment procedures.
21. 21. Method according to claim 20, characterized in that, the step of maintaining the painted substrate in a drying environment having a relative humidity in the range of about 25 to 95%, and a temperature in the range of about 7 ° to 51 °, it is carried out with a dehumidifying system that circulates recycled air and includes an evaporator, a reheating coil, a compressor, a remote condenser and a humidifier.
22. 22. - Method according to claim 20, characterized in that the dehumidifier system includes an air filtration system.