Abstract:
In order to decrease or eliminate environmental contaminants which are added to fluent particulate matter removed from bulk material carriers by vacuum conveyor systems, the bulk material carrier is moved into an enclosure which can be closed off from the environment after the carrier is within the enclosure. Clean air containing a prescribed maximum number of particles above a given size floods the entire enclosure and air of even greater cleanliness is fed to each hatch of the material carrier to entrain the particulate matter in the clean air streams which pass though the bulk material under the influence of the vacuum conveyor.

Description:
RELATED APPLICATION 
     This is a continuation-in-part of U.S. patent application Ser. No. 08/274,285 filed Jul. 13, 1994, and now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is directed to the movement of granular or fluent particulate matter from a shipping container to a point of use and more particularly to a clean air, vacuum operated bulk material handling system. 
     2. Description of the Prior Art 
     At present when it is desired to use a vacuum system unload a rail car or tank truck containing granular materials such as grain, corn kernels, beans, plastic pellets, or fluent particulate matter such as molding powders, carbon or lamp black, or coloring agents, the loading and discharge hatches of the rail car are opened to the surrounding environment and air is drawn into the rail car to entrain the granules or particles in the moving air stream. Unfortunately, since the fall car or tank truck is exposed to ambient environment, and often in a very industrial area, the air and grounds about the rail car or tank truck are highly contaminated and these contaminants can be drawn into the air stream as well as the granules and particulate matter and carried to the using station. These contaminants could alter the properties of the products being made at the using station. For example, if rubber is being molded, such contaminants could alter the physical or electrical properties of the resultant molded rubber product which could lead to its failure in the field. 
     SUMMARY OF THE INVENTION 
     The instant invention seeks to overcome the deficiencies noted with respect to the prior art by providing a clean air bulk material handling system which substantially reduces the introduction of any foreign matter and contaminants from the outside air into the air stream carrying the granular or particulate matter being unloaded from bulk carriers such as rail cars and tank trucks. This is accomplished by providing an enclosure for the bulk carrier which is extremely clean and which substantially reduces the contaminants entering such enclosure. The enclosure is supplied with outside air which has been filtered and heated and which is also extremely clean. Thus when the entraining of the granules or particles with the ambient air occurs, substantially no contaminants are added to the granules or particulate matter. It is an object of the instant invention to provide an improved bulk handling system for granular or particulate matter. 
     It is another object of the instant invention to provide an improved vacuum operated bulk handling system for granular or particulate matter. 
     It is another object of the instant invention to provide an improved bulk handling system for granular or particulate matter which prevents or minimizes the introduction of foreign or contaminant matter from outside of the system. 
     It is yet another object of the instant invention to provide an improved vacuum operated bulk handling system for granular or particulate matter which prevents or minimizes the introduction of foreign or contaminant matter from outside of the system. 
     It is still another object of the instant invention to provide an improved vacuum operated bulk handling system for granular or particulate matter which employs a contaminant-free enclosure for the bulk material carrying device and supply for entraining the granules and particulate matter in the system air stream. 
     Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principles of the invention, and the best mode which is presently contemplated for carrying it out. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings in which similar elements are given similar reference characters: 
     FIG. 1 is a top elevational view of a building constructed to facilitate practice of the method of the instant invention with the roof removed to reveal the details of the structures within. 
     FIG. 2 is a left end elevational view of the building of FIG. 1 with the walls and doors thereof removed to reveal the details of the structures within. 
     FIG. 3 is a front elevational view of the building of FIG. 1 with the wall removed to reveal the details of the structures within. 
     FIG. 4 is a schematic representation of the duct work of FIGS 1 to 3 to show the manner of supplying required air and removing spent air. 
     FIG. 5 is a fragmentary front elevational view of the building of FIG. 1 with the wall removed, a railway car in position and engaged by devices of the system and a roll-up door closed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning to FIGS 1 to 3 and 5 there is shown a building or enclosure 10 which can be used to enclose two railway cars RC 1  and RC 2  which contain granular or fluent particulate matter to be off-loaded by a vacuum conveyor system. To simplify the description, the term fluent matter will be used herein to refer to both granular and fluent particulate matter. It should be understood that although the description herein is made with reference to rail cars, the invention is equally applicable to tank trucks or other vehicles used to carry fluent matter and the building or enclosure employed would be a garage with similar features but without the rails or a building or enclosure which can handle both rail cars and tank trucks. 
     Building 10 is divided into two bays with a set of tracks 12 extending from a main track line (not shown) into Bay 1 to permit railway car RC 1  to be moved fully within enclosure 10 up to the end barrier or bumper 13. A second set of tracks 14 extending from the same main track line permits a railway car RC 2  to be moved fully into Bay 2 of the enclosure 10, up to the barrier or bumper 15. A set of roll-up doors RD 1  shown in FIG. 3 and RD 2  shown in FIG. 5 can now be moved from their open positions to close entrance 16 to Bay 1 and entrance 18 to Bay 2 as shown on FIG. 5. If desired to remove any environmental contaminants from the outside of the railway cars RC 1 , RC 2 , a car washing system (not shown) similar to a car wash could be employed before the railway cars RC 1  and RC 2  are moved into enclosure 10 or while in enclosure 10. 
     Building 10 has two substantially parallel walls, front wall 22 and rear wall 20, and two substantially parallel end walls, a left end wall 26 and a right end wall 24 when building 10 is viewed as it appears in FIG. 1. Left end wall 26 has, as stated above, two entrances 16 and 18 which are fitted with roll-up doors RD  1  and RD 2 , respectively, to close entrances 16 and 18. The floor 28 is raised as shown in FIGS. 2 and 3 but could also be placed directly upon the ground. Tracks 12 and 14 are contained in floor 28. Two roof support columns 32, 34 extend from floor 28 to the roof 30. Although roof 30 is shown as a centrally peaked roof, it could also be flat or inclined from one end to the other dependant upon local weather conditions. 
     FIG. 5 shows railway car RC 2  in building 10 with the roll-up door RD 2  in the closed position to close entrance 18 to Bay 2. A first hatch cover HC 1  is shown in the open position while the remaining hatch covers HC are shown in the closed position. The end of duct 73b is moved into position in the open hatch H 1  to supply clean air. As a result of the application of air to the fluent matter F in the railway car compartment C and the effects of the vacuum system drawing matter from railway car RC 2 , the fluent matter F at or near the surface S of the fluent matter is lifted and entrained in the air stream forming a cloud-like formation E which is drawn by the vacuum source 40 through collection fitting 36 attached to the bottom discharge hopper 38 of the railway car RC 2  and available at output pipe 42. 
     Turning to FIG. 4 the concept of the instant invention can be described. As stated above, the concept broadly stated is to provide fluent matter, which has substantially no on- site environmental contaminants, from a bulk material carrier to a vacuum conveyor system, wherein the bulk carrier is moved entirely into an enclosure which is then sealed with respect to the environment about the enclosure. Clean outside air, from which substantially all of the environmental contaminants have been removed, is provided to fill the bays of the enclosure about the carriers and still cleaner air, from which substantially all of any remaining environmental contaminants present in the clean air in the enclosure are removed, is provided to the carrier interior to provide a clean air stream to entrain the fluent matter and permit the fluent matter to be drawn into the vacuum conveyor. 
     Fresh outside air is drawn into the system at the entrance 52 to duct 50 by a blower 54. The fresh outside air is combined with the recirculated return air in duct 60 from registers 62 in Bay 1 and registers 64 in Bay 2. The amount of outside air which enters duct 50 is controlled by the motorized air damper 57 adjacent entrance 52 and the amount of recirculated return air which enters duct 50 is controlled by the relative settings of the motorized air damper 59 in the exhaust air duct 55. The motorized dampers, show by a rectangle enclosing the letters DM and coupled to a member with short diagonal lines, such as 57, 59, and 61, as well as the other motorized dampers shown, are coupled to and controlled by a computer system (not shown) which, among its other tasks yet to be described, controls the entire ventilation system and provides static pressure control employing a number pressure drop indicators, shown by the circles enclosing the letters PS and connected across medium efficiency filter 58 and supplies and input to the computer system as do all of the other pressure drop indicators shown. Using the various pressure drop indicator signals and other pressure indicators the computer can control the air stream flow to insure proper air flow. Temperature sensors, such as 63 connected to the return air duct 60, and shown by the circle enclosing the letters TC, sense the temperature of the return air and supply signals to the discharge temperature control system 65, shown in dashed lines, which in turn is connected to gas burner and heat exchanger section 68, as shown by the dashed lines, to control the heat applied to the air in duct 70. The combined fresh outside air and return air is passed through a medium efficiency filter 58 to duct 70. By controlling the amount of return air in duct 60 and the fresh outside air in duct 50 it is possible to produce the desired air flow within the enclosure 10. This flow may be in the order of 10,000 cubic feet per minute for an enclosure of the size of enclosure 10. The air flow can be increased or decreased for the specific enclosure or the material being handled, or the carrier, etc. 
     The air in duct 70 is passed through a second medium efficiency filter 66, and then through a HEPA (High Efficiency Particulate Air) filter 72 and then through a gas burner and heat exchanger section 68. The filtered and heated air is then provided to the bay air supply ducts 74 and 76 for Bay 1 and Bay 2 respectively via duct 70. This air is class 10,000 air. Federal Standard 209 D is the accepted method for measuring the degree of cleanliness and requires an actual count of the cumulative total number of particles of a particular size (diameter) or larger per unit volume of air. For the 10,000 class air, the air sample contains a maximum of 10,000 particles of 0.5 microns (0.0000005 meters) or larger, where 0.5 microns is the customary representative size. The air is also at a temperature of 65° to 95° F. and at a pressure of 2.50&#34; WC. 
     The air is supplied to the openable hatches of the railway cars via ducts 73a and 73b. The air supplied to ducts 73a and 73b is passed through HEPA filters 80 and 82. The air supplied by filters 80 and 82 is class 100 air which means that an air sample contains a maximum of 100 particles of 0.5 microns or larger. In the system described the particle size has been reduced to 0.3 microns rather than the standard 0.5 microns particle diameter permitted by the Federal Standard. 
     Returning now to FIGS. 1, 2, 3 and 4, the physical structure for collecting and distributing the air is shown. Fresh outside air enters entrance 52 of duct 50 and is advanced along duct 50 to where the recirculated return air duct 60 joins duct 50. The combined air is passed through duct 70 and the filters 58, 66, and 72 and on to the gas burner and heat exchanger 68 to raise the air temperature to a minimum 65° F. The gas required for the gas burner is supplied via gas line 51 through regulator 53. Part of the air which exits duct 70 is directed to duct 74 along the top of wall 22 which provides the air supply for Bay 1. Another portion of the air from duct 70 goes to duct 76 adjacent the top of wall 20 to provide the air supply for Bay 2. 
     The remainder of the air in duct 70 is divided between two additional ducts 73a and 73b. In passing from ducts 70 and 76 to each of the further ducts 73a and 73b the air goes through HEPA filters 80 and 82 respectively. The air in duct 73a is released next to the railway car RC 1  through a number of vent ports. Similarly, the air in duct 73b is released next to the railway car RC 2  through a number of vent ports. The vent ports should be aligned with the hatches available in each railway car and whose hatch covers are open and those not used may be suitably closed by their respective hatch covers to maintain 1.0&#34; WC of pressure in the system. 
     The air not employed in the air stream of the vacuum conveyor is removed by the ducts 60 near the floor 28 of enclosure 10 through registers 64 in Bay 2 and 62 in Bay 1 to be used as recirculated return air as above described. Excess air is exhausted via vent 55 in side wall 22 and building 10 is maintained at 0.1&#34; WC. 
     While there have been shown and described and pointed out the fundamental novel features of the invention as applied to the preferred embodiment, it will be understood that various omissions and substitutions and changes of the form, and details of the devices illustrated and in their operation may be made by those skilled in the art, without departing from the spirit of the invention.