Cleaning and liquid contact with solids – Processes – Including application of electrical radiant or wave energy...
Reexamination Certificate
2001-06-11
2003-10-07
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Including application of electrical radiant or wave energy...
C134S016000, C134S017000, C134S022100, C134S022180, C134S024000, C015S104030, C015S104050, C015S240000, C015S304000, C015S312100, C015S316100, C015S318000, C015S404000, C015S405000, C015S406000, C015S408000
Reexamination Certificate
active
06630032
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates, generally, to a method and apparatus for dislodging deposits from a vessel and, more specifically, to as method for dislodging deposits from a vessel using a gas impulse device.
BACKGROUND OF THE INVENTION
In the handling and storage of particulate solids, problems are encountered in various items of equipment. Most common of these items of equipment is the silo, generally a large, vertical, cylindrical vessel with a conical base fitted with an outlet valve mechanism. The term silo is, however, often used interchangeably with any of the terms bin, tank and bunker. Shapes vary, including those having square or rectangular cross-section and those with flat, pyramidal or dished bases.
A common problem occurring in silos as well as in other solid handling equipment is the accretion of particulate solids which eventually gives rise to reduced flow through the vessel or, in extreme cases, to complete blockage of the vessel.
In more serious cases of agglomeration, the flow from a vessel is partially or totally restricted by bridging of solids across the vessel outlet. Another, similar, problem is referred to as “rat-holing,” which also results in restricted flow from a vessel. When there occurs a severe build up of accumulated solids, specialized apparatus is generally required to remove the build-up. There are known in the art, mechanical methods for solving problems of undesired accumulation of solids. By way of example, where an undesirable accumulation of particulate matter is easily accessible, a hammer and chisel (manual or pneumatic) may be used to fracture and remove the agglomerated particles.
In the case of closed vessels with restricted manual access, such as a large silo, there are several known cleaning methods available. One method utilizes a device commonly referred to in the art as a “whip.” This device is pneumatically or hydraulically driven, and consists of a cutting head supported from the roof opening of a silo. The cutting head rotates rapidly so that flail chains attached to the head repeatedly strike the layer of accumulated material while the head is progressively translated upward or downward within the silo. This process is generally slow and rather cumbersome, and often poses a risk of damage to the silo being treated.
Other devices well known in the art for preventing or removing build-up of solids in flow through systems are air cannons and vibrators. Air cannons are, however, only moderately efficient for breaking up bridging and ineffective for overcoming rat-holing. Vibrators are only minimally effective for overcoming both bridging and rat-holing.
Apart from being time consuming and wasteful of resources, the implementation of such mechanical methods is generally known to be problematic. Furthermore, such mechanical processes are often known to create risk of dust explosion or fire, particularly when carried out in dusty environments. Where food or medicinal environments are concerned, such mechanical cleaning methods also give rise to considerations of hygiene. There also exists the possibility of emission of undesirable or harmful gases.
Referring to U.S. Pat. No. 4,571,138 to Farajun, entitled “Apparatus For Silo Clean Out,” there is described apparatus for cleaning solids that have accumulated in places of restricted access such as silos, hoppers and the like. This cleaning apparatus includes a power driven device for impacting the accumulated material and allowing it to fall away. The device for impacting the solids is suspended from and powered by a cable and hose combination, which is reeled onto a drum supported above the material in the silo. The drum is rotatable to reel-out or reel-in the cable and hose to position the impacting device in the vicinity of the material to be removed. The apparatus includes provision for automatically reversing the impacting device along the material face and, in the event of a material avalanche, for releasing the drum to allow the impacting device to fall downwardly with the flowing material in the silo.
Referring now to U.S. Pat. No. 4,881,856 to Greig, entitled “Chip Snake,” there is described a cleaning device for loosening and removing accumulated material, such as wood chips, in silos, using a raking action of regularly spaced spikes and a flailing action of a hose with a jet stream nozzle. The device includes a hose, connected to a compressed air supply, and a nozzle at the end of the hose. Compressed air is passed through the hose and exits the nozzle causing the nozzle and hose to move under the influence of the expelled compressed air. Spikes are attached along the hose to provide regularly spaced raking elements. Anti-kink mechanisms maintain the hose in a straight alignment. The operation involves lowering the nozzle into a silo in the vicinity of agglomerated material. Then compressed air is introduced into the hose and expelled out of the nozzle in a jet stream, thereby causing the hose and nozzle to move about in the silo, so that the spikes strike and dislodge the impacted material.
Further, referring to U.S. Pat. No. 4,942,982 to Hartwigsen, et al., entitled “Silo Cleaning Apparatus,” there is described apparatus for cleaning a silo which has a mass of agglomerated particles. Dislodging the accumulated mass is achieved by extending at least one flexible tube connected to a bludgeon into the silo near to the accumulated mass and introducing gas through the tube and bludgeon at a rate and pressure that causes swinging and writhing movements by the bludgeon and tube.
Referring also to U.S. Pat. No. 5,649,338 to Kato, entitled “Automatic Interior Cleaning System For A Powdered Material Processing Device,” there is described an automatic interior cleaning system for processing equipment for handling finely divided material. The equipment requiring cleaning includes interior surfaces of, for example, silos, mixers, and dust collectors. A compressor and a gas storage tank supply gas, preferably air, at a sufficient pressure to dislodge residues of materials that collect on interior surfaces. A valve connecting the gas tank to a cleaning-nozzle tube opens and closes, supplying pulses of air to the cleaning nozzle tube. The cleaning nozzle tube delivers the pulses through slots in the tube to the inner surface of the equipment requiring cleaning. The pressurized air pulses produce shock waves, which dislodge any residues from the interior surface. Automatic removal of residues during processing prevents contamination of subsequently processed materials.
Other known processes for the cleaning of closed vessels utilize liquid carbon dioxide for effecting cavitation erosion of accumulated solids. Such processes are employed where mechanical methods pose a risk of flammability.
Referring to U.S. Pat. No. 5,316,591 to Chao, et al., entitled “Cleaning By Cavitation In Liquefied Gas,” there is described the removal of undesired material from a chosen substrate by a process comprising placing the substrate containing the undesired material in a cleaning chamber provided with means for causing cavitation. The process involves introducing a liquefied gas, such as liquid carbon dioxide, into the cleaning chamber in contact with the substrate containing the undesired material, with the liquid carbon dioxide at a temperature below its critical temperature. Exposing the liquid carbon dioxide to the cavitation-producing means for a period of time is sufficient to remove the undesired material from the substrate. The substrate containing the undesired material may optionally be contacted with carbon dioxide in the dense phase prior to and/or after the cavitation treatment to aid in removal of the undesired material. Further, spent liquid carbon dioxide may be treated to regenerate fresh liquid carbon dioxide, which is recycled to the cleaning chamber. Other gases besides carbon dioxide, which may be used, include nitrous oxide, sulfur hexafluoride, and xenon.
In a similar manner to that described in U.S. Pat. No. 5,316,591 quoted above, carbon dioxide, at a temp
Ass Yuri
Carmi Gennady
Gulakowski Randy
Kornakov M.
Lilling & Lilling P.C.
ProWell Technologies, Ltd.
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