Patent Application
20060070722
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.
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'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.
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.
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.
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.
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.
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.
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's charging rate, exacerbates the deleterious effects of any leaks which may be present in the system.
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.
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.
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.
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.
The system and methodology of the present invention are depicted in the accompanying drawings which form a portion of this disclosure and wherein:
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.
The air cannon manifold 10 may be seen in greater detail in
In the embodiment shown, inlet valve 21 is best seen in
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
We have found a preferred configuration for inlet seal 25 and exhaust seals 35. According to our preferred embodiment, shown in
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.
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
As may be seen in
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.
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.
In addition, as shown in
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's scope as defined in the following claims.
