Abstract:
An apparatus for cleaning deposits from the interior surfaces of an industrial vessel, such as a kiln. The apparatus utilizes an air cannon manifold for selectively directing and venting a high volume of pressurized fluid to any one or more of a plurality of access ports defined in the vessel whereby the pressurized fluid is directed at the deposits to prevent them from adhering and accumulating on the walls of the vessel. A controller is provided to permit selection of a desired exhaust port for directing the pressurized fluid to the access ports and for sequencing an inlet valve in cooperation with a desired exhaust port.

Description:
FIELD OF THE INVENTION  
       [0001]     The instant invention relates to air cannons used for cleaning and preventing the buildup of deposits on the walls of industrial vessels, such as kilns used in the cement and paper industries. More particularly, the instant invention relates to a manifold for selectively directing the blast from an air cannon to any one of a plurality of ports of an industrial vessel for removing and preventing the build up of material deposits therein.  
       BACKGROUND OF THE INVENTION  
       [0002]     In industrial vessels, such as cement, wood or paper kilns, and their associated structures, the accumulation of particulate deposits on the inner linings of these vessels is a recurring problem. Buildup of deposits in areas such as preheater and riser ducts can choke off feed pipes and cyclones and greatly affect the efficiency and production performance of the vessel, even to the point of causing unscheduled shutdowns. If deposits are permitted to accumulate the high temperatures typically encountered in vessels, such as kilns, will cause the deposits to become encrusted on the kiln&#39;s interior surfaces. The precise characteristics of the buildup in these vessels may vary from plant to plant, the process employed, and can even vary from hour to hour within the same plant or process.  
         [0003]     Usually, the buildup begins sticking to the walls of the vessel lining with the consistency of talcum powder. Routine cleaning of the deposits is a preferred method of addressing the problem such that the deposits are removed before significant accumulation and encrustation occurs.  
         [0004]     Air cannons have long been an accepted method for routine cleaning of vessel walls and maintaining material flow in many industrial applications. While there are many different configurations of air cannons, the principle of operation for all air cannons is the same. A large volume of air is exhausted in a short period of time through a access port in the vessel wall, creating a powerful burst of air which dislodges particulate material that has adhered to the internal wall of the vessel. The various configurations of air cannons are generally differentiated based on their air discharge velocity and the design of the inlet seal for the associated air reservoir. However, each of the various air cannon configurations in use utilize a separate air reservoir as part of an air cannon attached to the particular vessel access port. This configuration poses many problems to those in the affected industries.  
         [0005]     The first concerns the installation costs associated with independently mounted air cannons. For each air cannon in the system, a separate air reservoir incurs the added cost of purchasing and maintaining the reservoir as well as installation costs associated with routing the necessary air lines to charge each reservoir and additional wiring activate the individual air cannons. In some instances, attempts to avoid these installation costs have been made whereby an air cannon assembly is moved from access port to access port to clean the respective areas of the vessel. While saving on installation costs, this practice incurs its own costs in that an employee is required to reposition the air cannon to a desired access port.  
         [0006]     A second concern is the space requirements for installing and operating individual air cannons with an integrated air reservoir. Traditional air cannons with their individual air reservoirs require a substantial amount of space to install and once installed they present an obstacle for the operators working around the particular vessel.  
         [0007]     Third, the typical air cannon is mounted in close proximity to the vessel, and most are mounted directly to the vessel. Usually the processes within the vessel generate a substantial amount of heat and considerable particulate debris. In these harsh environments, traditional air cannons frequently experience premature wear and failure of internal components, particularly in its valve assemblies.  
         [0008]     In many instances the valves used to control the flow of air from the reservoir require the maintenance of a pressure differential within the valve body. In order to maintain this pressure differential within acceptable tolerances, the rate at which the reservoir may be charged is restricted such that subsequent firing of the cannon is delayed considerably. Moreover, because the restriction in the reservoir&#39;s charging rate, exacerbates the deleterious effects of any leaks which may be present in the system.  
       SUMMARY OF THE INVENTION  
       [0009]     The air cannon manifold of the present invention addresses these problems in the industry by providing an air cannon manifold that permits a plurality of access ports to be serviced by a single air reservoir, providing a reliable cost effective solution to the aforementioned problems. First, it reduces installation costs by eliminating the requirement for a separate air reservoir at each air cannon portal. By eliminating the requirement for a separate air reservoir, additional savings are realized at initial installation by eliminating the requirement to install a separate air line to charge each separate air reservoir.  
         [0010]     Second, by eliminating the requirement for an individual air reservoir at each air access port, the initial space requirements may be reduced for new installations employing the air cannon manifold of the present invention. Similarly, modification of existing installations to incorporate the air cannon manifold will permit reclamation of valuable work space previously occupied by the individual air reservoirs servicing the existing air cannon ports. In both instances, obstructions in close proximity to the vessel are eliminated, permitting workers around the vessel a safer work environment.  
         [0011]     Third, the air cannon manifold of the present invention further permits the working components of the system, such as its valves and sensors, to be positioned away from the high temperatures and debris generated by the vessel, resulting in improved reliability and extending the service life of the components and the system.  
         [0012]     Finally, the air cannon manifold of the present invention enables rapid charging of the reservoir to permit a single reservoir to service a plurality of cleaning ports or to permit successive firing into any selected cleaning port. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The system and methodology of the present invention are depicted in the accompanying drawings which form a portion of this disclosure and wherein:  
         [0014]      FIG. 1  is a perspective view of an air cannon manifold and an air reservoir;  
         [0015]      FIG. 2  is a side view of an air cannon manifold;  
         [0016]      FIG. 3  is a perspective view of the air cannon manifold from an input side, with an actuator removed to show an exhaust actuator bore;  
         [0017]      FIG. 4  is a partial sectional view of an exhaust valve;  
         [0018]      FIG. 5  is a partial sectional view of an inlet valve;  
         [0019]      FIG. 6  is a partial sectional view of an inlet valve and exhaust valve in their open position;  
         [0020]      FIG. 7  is a schematic diagram for sequentially selecting an exhaust port to be serviced by the air cannon manifold; and  
         [0021]      FIG. 8  is a schematic diagram for monitoring and signaling alarm conditions of the air cannon manifold.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]     Referring to the drawings for a clearer understanding of the invention, it may be seen that a preferred embodiment of the invention contemplates a single air reservoir  11 , providing a high volume pressurized air source for an air cannon system, connected to the air cannon manifold  10  via an inlet duct  12  attached to an inlet port  20 . A plurality of exhaust ducts  13  interconnect exhaust ports  30  of the air cannon manifold  10  with the access ports of an industrial vessel, such as a kiln and its associated structures.  
         [0023]     The air cannon manifold  10  may be seen in greater detail in  FIGS. 2-6 . As depicted, air cannon manifold  10  comprises a housing  14 , defining a plenum therein. An inlet port  20  extends through a first wall  15  in housing  14  and receives high volume pressurized air from a source such as a pressurized air reservoir  11  via an inlet duct  12 , such as the elbow connector shown in the drawings. Inlet duct  12  may be a pipe or similar conduit and may be bolted to manifold  10  through a flange  17 , or any suitable attachment means. An inlet valve  21  is provided to control the flow of air from reservoir  11  to manifold housing  14  by selectively opening and closing inlet port  20 .  
         [0024]     In the embodiment shown, inlet valve  21  is best seen in  FIGS. 5 and 6 , and comprises an inlet valve actuator  22 , such as a pneumatic cylinder or the like attached to second wall  16  of manifold housing  14  an adapter plate  18  and opposing inlet port  20 . An inlet actuator shaft  23 , is extensible through an inlet actuator bore  24  defined in the second wall  16  of manifold housing  14  and closed by plate  18 . An inlet valve seal  25  is attached to a distal end of inlet actuator shaft  23 , and is selectively positioned by inlet valve actuator  22  for sealing engagement with an inlet seat  26 , defined on an interior face of first wall  15 . Preferably inlet actuator bore  24  will be dimensioned to be larger than inlet valve seal  25 , to facilitate removal of inlet valve  21  for servicing or replacing this component.  
         [0025]     Air cannon manifold  10  further defines a plurality of exhaust ports  30  in a second wall  16  of housing  14 . Exhaust ducts  13  are connected to exhaust ports  30  to communicate the high volume air released into the manifold  10  to a corresponding access port in vessel. Exhaust ducts  13  may be a pipe or similar conduit and may be bolted to manifold  10  through an exhaust flange  18 , or any suitable attachment means. An exhaust valve  31  is provided for each exhaust port  30  to control the flow of air delivered by manifold  10  to a desired access port in vessel serviced by the air cannon. Exhaust valves  31  are selectively positionable to open and close their associated exhaust ports  30 . As best depicted in  FIGS. 4 and 6 , exhaust valves  31  comprise an exhaust valve actuator  32 , such as a pneumatic cylinder, attached to housing first wall  15  and opposing their respective exhaust ports  30 . An exhaust actuator shaft  33 , is extensible through an exhaust actuator bore  34  defined through first wall  15 . Exhaust valve seals  35  are attached to the distal ends of exhaust actuator shafts  33  and are selectively urged against exhaust port seats  36  by exhaust valve actuators  32 . As with the inlet valve  21 , exhaust actuator bore  34  is preferably dimensioned to be larger than exhaust valve seal  35  to facilitate removal of exhaust valves  31  for servicing or removal of these components. A protective ring  43  may also be attached to an inner surface of first wall  15  coaxial with actuator bore  34 , and extending inwardly therefrom, such that upon opening of exhaust valve  31 , exhaust valve seal  35  may be retracted into ring  43  to avoid exposure to the high velocity air experienced within housing  14  upon opening inlet valve  21 . Each exhaust valve  31  is independently controllable to permit selective routing of the air blast to a desired access port in the vessel to clean the respective areas of the vessel walls based on the vessel&#39;s operating conditions.  
         [0026]     We have found a preferred configuration for inlet seal  25  and exhaust seals  35 . According to our preferred embodiment, shown in  FIGS. 4 and 6 , seals  25  and  35  comprise a disk portion  41 , extending from and coaxial with a chamfered disk portion  42 . Cylindrical disk portion  41  has a diameter smaller than that of the inner diameter of the respective inlet port  20  or exhaust port  30  to facilitate positive alignment of the seals  25 ,  35  in the respective ports  20 ,  30 . The chamfered disk portion  42  has a diameter greater than disk portion  41 , and provides for sealing engagement with the respective valve seat  26 ,  36 . More preferably, chamfered portion  42  is made of a resilient material to improve its sealing engagement as it is urged against the valve seat  26 , 36 .  
         [0027]     Our preferred embodiment inlet actuator  22  and exhaust actuator  32  are mounted with their operative mechanisms external to manifold housing  14 . This arrangement provides the advantage of permitting ready access to the actuators  22 ,  32  for routine inspection, maintenance and servicing. This arrangement also provides an advantage in that the positioning of the operative mechanisms avoids exposure to the large pressure differentials encountered within manifold housing  14  during cannon firing sequences.  
         [0028]     Having thus described an exemplar of our air cannon manifold, its preferred method of operation will be described. A typical single duty cycle, for the air cannon manifold comprises the steps of sealing inlet port  20 , charging the air reservoir  11  with air from a pressurized air source, opening a desired exhaust port  30 , and opening inlet port  20  to permit venting of the pressurized air form reservoir  11  to the desired access port on the vessel to be cleaned. This process may be controlled either manually or automatically. A schematic diagram for a controller  50  directing sequential firing of a three port air cannon manifold is shown in  FIG. 7 .  
         [0029]     As may be seen in  FIG. 7 , the sequential firing cycle is initiated at II, which initiates an air reservoir  11  charging cycle, B 02  through Q 6 , and exhaust port  1  activation cycle, B 09  through Q 2 . The exhaust port  1  activation cycle delays opening of a first exhaust valve  30  (normally closed) for sufficient time to permit completion of the air reservoir  11  charging cycle. It should be noted that by maintaining the exhaust valves  30  in the normally closed position we can significantly reduce the deleterious effects of any back draft from the vessel that may carry particulates or high temperature air into manifold housing  14 . Once sufficient time has elapsed to charge air reservoir  11 , the first exhaust valve  30  is activated and is held open for a sufficient duration to permit completion of the inlet valve firing sequence, B 04  through Q 1 . Upon activation of the inlet valve firing sequence, inlet valve  20  is opened, permitting the rapid venting of the pressurized air in air reservoir  11  through air cannon manifold  10 , first exhaust port  30  and its associated exhaust duct  13 , to the desired access port on the vessel to be cleaned. Completion of the first exhaust valve  30  activation sequence Q 2 , resets the air reservoir charging sequence and initiates activation of the cycle for a second exhaust port  30 , which proceeds in like manner to that described for the first exhaust port cycle. It varies from the first exhaust port cycle in that signal Q 3  resets the first exhaust port cycle so that first exhaust valve  30  is maintained in a closed position. A third exhaust port  30  is activated in like manner and restarts the sequenced firing cycle.  
         [0030]     We have found that when a pneumatic actuator is used for the inlet valve actuator  22  and that actuator is reliant on the same air source that is used to charge reservoir  11  it is desirable that the charging of reservoir  11  be delayed while inlet valve  21  is being closed to ensure that sufficient pressure is available to reliably activate inlet valve actuator  22  for sealing inlet port  20 . This may be accomplished by temporarily closing a valve to block the communication of the pressurized air source to reservoir  11  for sufficient time to permit the closure of inlet valve  21 . The temporary interruption of airflow to reservoir  11  also facilitates alignment of inlet valve seal  25  as residual air flow through inlet port may cause misalignment of inlet valve seal  25 .  
         [0031]     Automatic control of the air cannon manifold  10  may also be provided by monitoring process specific variables, such as temperature, oxygen content, or the like, that would indicate particulate accumulation at any particular location within the process vessel. In this circumstance, the blast cannon manifold controller  50  would be specifically targeted to remedy particulate accumulations based on the indications of the particular process specific variable, thereby improving the efficiency and efficacy of the blast cannon system in maintaining the cleanliness of the process vessel.  
         [0032]     In addition, as shown in  FIG. 8 , the blast manifold controller  50  may also provide notification of user determined alarm conditions within the air cannon manifold  10  or air cannon system or vessel process that may potentially impact the safety or efficiency of the process for which the air cannon is employed.  
         [0033]     It is to be understood that the form of the invention as shown herein is a preferred embodiment thereof and that various changes and that modifications may be made therein without departing from the spirit of the invention&#39;s scope as defined in the following claims.