Cleaning and liquid contact with solids – Apparatus – For work having hollows or passages
Reexamination Certificate
1998-07-30
2001-03-27
Stinson, Frankie L. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
For work having hollows or passages
C134S16700R, C134S198000, C239S743000
Reexamination Certificate
active
06206016
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for cleaning the interior surface of a pipe and more specifically for cleaning the interior surface of a sewer pipe.
BACKGROUND OF THE INVENTION
Pipes used to carry liquids and gases commonly transport all types of materials including water, natural gas, solid and liquid sewage, as well as various other accumulations from the pipe. Over time, these pipes require servicing and cleaning. Taylor et al. disclose automated systems for cleaning the outside of a pipeline in U.S. Pat. No. 5,520,734. Taylor et al. excavate under subterranean pipe and restore it by first cleaning the pipe and then applying a protective coating to the outer surface. As yet, however, nobody has automated a process for cleaning or restoring the inside of a pipe.
The interior surface of a pipeline carrying solids, liquids and gases generally degrades over time as the pipe walls interact chemically and physically with the substances flowing through them. In particular, a sewer system's interior walls corrode and deteriorate because corrosive materials contaminate the surface degrading the metal and concrete used to build the sewer. The corrosive material arises from both the sewage and waste water itself, and also from the digestive by-products of bacteria found in the sewage which proliferate in the anaerobic environment. The corrosion causes the walls of the sewer pipe to physically decay, eventually reducing their overall thickness.
The principal source of corrosion is sulfuric acid, which arises as a product of the materials transported in a sewer pipe and the sewer environment itself. Various metal sulfates found in the sewage quickly convert into hydrogen sulfide by: reducing to sulfide ions in the waste water, combining with hydrogen in the water and outgassing above the liquid as hydrogen sulfide gas. Additional hydrogen sulfide originates from bacteria containing contaminants which accumulate on the relatively rough concrete below the maximum liquid level. Bacteria found in these accumulations thrive in the anaerobic sewer environment producing hydrogen sulfide gas as a respiratory bi-product. Oxygen from the liquid below and oxygen condensing from the water in the air react with the hydrogen sulfide on the pipeline walls creating the highly corrosive sulfuric acid. The sulfuric acid attacks the calcium hydroxide in the concrete sewer walls leaving calcium sulfates which ultimately crumble and fall off of the interior of the wall substantially reducing its thickness.
The waste water level varies over the course of a 24 hour period. The flow is at its lowest level between 1:00 AM and 6:00 AM in the morning but it rises distinctly in the daytime and the pipe may operate near capacity. Because of the gaseous nature of the hydrogen sulfide, the pipe walls are predominately corroded in the portions of the wall above the minimum liquid level. Portions of the walls which are always below the water level are not subjected to such high concentrations of hydrogen sulfide gas or sulfuric acid and consequently do not experience the same levels of decay.
Eventually the sewer walls must be restored or they can suffer permanent damage leading to great expense. The restoration process is a two step operation that consists of first cleaning all of the contaminants (including any possibly existing outer layers of corrupted concrete) from the surface of the pipe, i.e. a process herein defined as scarifying, and then applying a protective coating over the newly cleaned (scarified pipe surface. Attempting to apply a protective coating without as aforesaid first cleaning the pipe surface is futile because it does not stop the decay that has already began underneath the coating. Furthermore, the protective coating itself does not adhere well to the contaminated surface. Thus, cleaning is an essential element of the restoration process.
As previously mentioned, a sewer system typically operates at high capacity during the day with decreasing flow overnight. In order to restore the sewer pipes without diverting the flow (a costly and sometimes impossible alternative), a bulk of the work must be done at night during the brief period when the flow is at a minimum. As previously outlined, the restoration process involves both cleaning the pipe surface and applying a protective coat. In practice, the rate of restoration is impaired because manual cleaning takes a proportionally greater amount of time than does the application of the protective coat. Consequently, a need exists for an automated cleaning process. Such a process will improve the rate of cleaning of the pipeline's interior walls making restoration without diversion a cost-effective possibility. Further, automation of the process can help to ensure that the same intensity of cleaning is applied to the entire surface without the quality variation that is inherent in manual execution.
Several patents such as Taylor et al. (U.S. Pat. No. 5,520,734), describe automated processes for cleaning the outside surface of pipelines using spray nozzle jets; however, none have attempted to automate the cleaning of the interior surface of a pipeline.
SUMMARY OF THE INVENTION
The following is a brief description of the invention, its parts and its functionality.
The present invention is a two part system for cleaning the interior surface of a pipe which includes a “vehicle” which can move along the interior of the pipe and a “cleaning system” attached to that vehicle. As the vehicle moves, the cleaning system cleans a selected region of the interior surface of the pipe.
At its most basic level, the cleaning system may include a fluid coupler with a flow control valve which is coupled between a source of pressurized fluid and a spray nozzle. The spray nozzle may direct a jet of pressurized fluid against the interior surface of said pipe.
The cleaning system may be further described in terms of an “arm” mounted at one end to the vehicle chassis, a “spray nozzle assembly” rotatably mounted to the arm, and an “exchanger” coupled between the fluid coupler with the flow control valve and the spray nozzle assembly. The cleaning system arm and/or spray nozzle assembly may be adjustable so as to position said spray nozzle assembly in proximity to the interior surface of the pipe. The exchangers may distribute fluid from the fluid coupler with the flow control valve to the parts of the spray nozzle assembly.
The spray nozzle assembly may further comprise a plurality of branches which may be rotatably attached to said exchanger. The branches may be rotatable about a common axis and may conduct fluid from the exchanger. Each of the branches may be equipped with at least one spray nozzle. The spray nozzles may be operative to receive pressurized fluid from the branches and expel it against the interior surface of the pipe.
The apparatus is adaptable to clean the interior surface of the pipe in many different fashions. A first cleaning system is adjustable so that one of the arm and/or the spray nozzle assembly is positionable so as to locate the nozzles adjacent to the interior surface of the pipe and to clean a longitudinal swath of the pipe in a direction of travel of the vehicle. Alternatively, the cleaning system arm and/or spray nozzle assembly may be configured so as to rotate about an axis substantially parallel to the longitudinal axis of the pipe, so that the pressurized fluid expelled from the nozzles impacts an entire circumferential swath of the pipe's interior surface. The arm and/or spray nozzle assembly may also be positionable so as to locate the nozzles adjacent to a bottom surface of the pipe. The pressurized fluid expelled by the nozzles may then clean a longitudinal swath along the bottom surface of the pipe.
The vehicle may comprise a chassis which may be adjustable to fit various pipe sizes an may support the apparatus, a track assembly which may propel the vehicle along a longitudinal direction of the pipe as it rotates, a motor mounted on the apparatus and coupled so as to drive the track as
Bose Vernon
MacNeil David
MacNeil Gerard
MacNeil Gordon
Hall Priddy Myers & Vande Sande
Mac & Mac Hydrodemolition Inc.
Stinson Frankie L.
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