Cleaning apparatus for exhaust system and method

The present invention provides for a cleaning apparatus for a vertical exhaust pipe in an exhaust system, the cleaning apparatus comprising a cleaning liquid source, an enclosure receiving a cleaning liquid from the cleaning liquid source, and a fluid communication between the enclosure and an inner surface of the exhaust pipe so that the cleaning liquid supplied to the enclosure by the cleaning liquid source is gravity fed into the exhaust pipe through the fluid communication, thereby creating a cleaning liquid film flowing down along at least part of the inner surface of the exhaust pipe, whereby the cleaning liquid film washes the at least part of the inner surface of the exhaust pipe. The cleaning apparatus is thus efficient, has a low risk of failure and is easily accessible for maintenance. A method for cleaning a vertical exhaust pipe in an exhaust system is also provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to exhaust systems, and more particularly to cleaning apparatus for the exhaust pipes of such systems.

2. Background Art

Industrial exhaust systems usually include exhaust ducts used to vent gases from an environment. These gases, mostly composed of air, often contain particles which are susceptible to create deposits on the exhaust ducts. Such deposits can interfere with the efficiency of the exhaust system, damage the exhaust ducts if the deposits are corrosive, create a fire risk if the deposits are flammable or an explosion risk if the deposits are unstable. Accordingly, various cleaning apparatus have been set forth to either remove these particles from the exhaust gas or clean the deposits from the exhaust pipes.

U.S. Pat. No. 2,387,345 issued May 14, 1942 to Pearl discloses an apparatus for washing exhaust gas coming out of a stack. This apparatus comprises a cylindrical shell which is installed over the top end of the stack and includes a plurality of nozzles delivering water in various direction to wash the exhaust gas. However, this apparatus does not provide for washing of the interior surface of the stack, where deposits will tend to accumulate.

U.S. Pat. No. 5,860,412 issued Jan. 19, 1999 to Way presents a system for cleaning a kitchen ventilation duct. The system includes a length of piping disposed longitudinally within the duct and possessing a plurality of nozzles regularly spaced apart delivering cleaning fluid on the inner surface of the duct walls. However, such a system would require a large number of nozzles in the case of long ducts, which can be expensive. The length of piping and nozzles can obstruct the exhaust flow moving up the duct. In addition, the plurality of nozzles represent a large number or elements that can potentially fail in the system. Finally, maintenance or replacement of the various elements such as the nozzles can be difficult due to their location inside the duct.

Accordingly, there is a need for an efficient cleaning apparatus for an exhaust system which has a low risk of failure and is easily accessible for maintenance.

SUMMARY OF INVENTION

It is therefore an aim of the present invention to provide an improved cleaning apparatus for a vertical exhaust pipe of an exhaust system.

Therefore, in accordance with the present invention, there is provided a cleaning apparatus for a vertical exhaust pipe in an exhaust system, the cleaning apparatus comprising a cleaning liquid source, an enclosure receiving a cleaning liquid from the cleaning liquid source, and a fluid communication between the enclosure and an inner surface of the exhaust pipe so that the cleaning liquid supplied to the enclosure by the cleaning liquid source is gravity fed into the exhaust pipe through the fluid communication, thereby creating a cleaning liquid film flowing down along at least part of the inner surface of the exhaust pipe, whereby the cleaning liquid film washes the at least part of the inner surface of the exhaust pipe.

Further in accordance with the present invention, there is also provided a method for cleaning a vertical exhaust pipe in an exhaust system, the method comprising the steps of providing an enclosure in fluid communication with the exhaust pipe, the fluid communication being above a portion of an inner surface of the exhaust pipe to be cleaned, supplying a cleaning liquid to the enclosure, allowing the cleaning liquid to be gravity fed from the enclosure through the fluid communication into the exhaust pipe such as to create a cleaning liquid film flowing down along the portion of the inner surface, and removing deposits on the portion of the inner surface through the flowing of the cleaning liquid film.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now toFIG. 1, an exhaust system, generally indicated at10, is shown. The exhaust system10comprises a vertical exhaust pipe12which is connected at a bottom end thereof to a source of exhaust gas (not shown). The exhaust pipe12is surrounded by an outer duct16so as to create an annular space around the exhaust pipe12to receive insulation material18. The exhaust pipe12and outer duct16are preferably made of fiber reinforced plastic (FRP) while the insulation material is preferably composed of “R-12” fiberglass.

The exhaust system10is similar to that described in U.S. Pat. No. 3,134,345 issued May 26, 1964 to King, which is incorporated herein by reference, and as such will only be briefly explained. A venturi20, i.e. a constricted section designed to create a pressure drop in a fluid flow, is included in the exhaust pipe12. A curved pipe22, comprising a vertical portion24connected to an horizontal portion26, penetrates the exhaust pipe12such that the vertical portion is centered in the pipe12and aligned with the bottom part of the venturi20. The horizontal portion26is connected to a centrifugal fan34through a flexible connector28, a reducer30and a damper32. In operation, the centrifugal fan34provides a flow of air through the curved pipe22and up the venturi20. In the venturi20, the pressure of the forced air flow drops, creating a vacuum that “pulls” the exhaust gas from the bottom of the exhaust pipe12.

The exhaust pipe12is connected along a top end thereof to a washing ring50, which is detailed inFIGS. 2-3. Like the exhaust pipe12, the washing ring50is preferably made of FRP. The washing ring50comprises an annular enclosure59which is defined by a bottom wall52, an outer wall54, a top wall56and part of a wall58of the exhaust pipe12. The exhaust pipe wall58is connected along a top edge thereof to a flange60extending inside the enclosure59. An annular gap between the flange60and the top wall56of the enclosure59creates an annular opening62which provides fluid communication between the enclosure59and the interior of the exhaust pipe12. A water pipe64(also shown inFIG. 1) is connected to the bottom wall52of the enclosure59. The water pipe64is connected to a pressurized water source (not shown), preferably through a three-way valve (not shown) so as to allow emptying of the enclosure59and the water pipe64when the washing ring50is not in use. A deflecting block66is provided in the enclosure59over the connection of the water pipe64to help deflect incoming water around the perimeter of the enclosure59.

In operation, water from the water source is delivered through the water pipe64to the enclosure59, filling it then overflowing through the annular opening62. The flow of water is adjusted so that the overflowing water will create a thin film flowing down along the entire perimeter of the inner surface of the exhaust pipe wall58. This water film will wash away deposits left on the inner surface of the pipe wall58by the exhaust gas. The adjustment of the water flow is critical, since a high flow tends to push the water film away from the inner surface of the pipe wall, while a low flow tends to produce an insufficient water film to efficiently wash away the deposits. The water containing the deposits is disposed of at the bottom of the exhaust pipe12through any adequate means, such as a reservoir, a drain pipe, etc.

In the case of tall exhaust pipes, the water film can become saturated in deposits before reaching the bottom of the pipe and thus losses its cleaning efficiency. Additional washing rings150, such as shown inFIGS. 4-5, can be regularly disposed along the height of the pipe112such as to provide a fresh water film, for example one every ten (10) feet. In this embodiment, the washing ring150is used to connect exhaust pipe sections114forming the tall exhaust pipe112(in broken lines in the figures).

The washing ring150comprises an annular enclosure159which is defined by a bottom wall152, an outer wall154, a top wall156and an inner wall158. The inner wall158, aligned with the walls of the exhaust pipe sections114, also acts as an exhaust pipe wall within the height of the ring150. The inner wall158includes an annular opening162, preferably located just below the top wall156of the enclosure159. As in the previous embodiment, the bottom of the annular opening162is preferably bordered by a flange160extending in the enclosure and connected to the inner wall158. A water pipe164is connected to the bottom wall152of the enclosure159and to a pressurized water source, preferably through a three-way valve. A deflecting block166is provided in the enclosure159over the connection of the water pipe164to help deflect incoming water around the perimeter of the enclosure159.

The inner wall158ends by an annular connecting flange168both at the bottom and top end of the washing ring150. Both connecting flanges include regularly angularly spaced apart bolt holes170. The exhaust pipe sections114also each include a connecting flange115with similar bolt holes117. Each exhaust pipe section114is connected to the washing ring by attaching the connecting flanges115,168together with a series of bolts (not shown) through the bolt holes117,170.

As in the previous embodiment, water from the water source is delivered through the water pipe164to the enclosure159and overflows through the annular opening162, creating a thin film flowing down along the entire perimeter of the inner surface of the inner wall158and continuing along the inner surface of the wall of the pipe section114under the ring150. The water film washes the deposits on the inner surface of the pipe wall.

Although the washing rings50,150have been described as using water to clean the exhaust pipe12, another appropriate cleaning solvent could also be used together with or instead of water. Also, the washing rings50,150can be used with other types of exhaust pipes not including a venturi system.

The embodiments of the invention described above are intended to be exemplary. Those skilled in the art will therefore appreciate that the forgoing description is illustrative only, and that various alternatives and modifications can be devised without departing from the spirit of the present invention. Accordingly, the present is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.