Cleaning station for cleaning parts of an exhaust gas processing apparatus

A cleaning station for cleaning parts from apparatus that itself uses a water spray to clean a toxic gas. The cleaning station has a tray and a sink for holding a part to be spray cleaned and the sink is connected to drain the spray water into the drain system of the gas cleaning apparatus.

FIELD OF THE INVENTION 
This invention relates generally to apparatus for cleaning parts of a gas 
cleaning apparatus. More specifically, this invention relates to apparatus 
for cleaning the parts of a CDO (controlled decomposition and oxidation) 
apparatus. 
Introduction 
CDO apparatus is well known, but it will be helpful to review the features 
of apparatus of this type that particularly apply to this invention. 
The apparatus receives an exhaust gas and vapors at one end and releases 
processed gas at its other end. For describing the process, the apparatus 
can be divided into several sections. In a thermal reaction section, the 
exhaust gas and vapors are heated and their combustible components are 
burned or otherwise undergo a thermal reaction. The thermal process 
creates a powder (or ash) that for the most part is carried by the gas. 
The next two sections of the apparatus are cooling and scrubbing sections 
where water is sprayed into the gas to remove the powder. 
The apparatus is formed in a U shape with the two cooling and scrubbing 
sections at the bottom, one on each side of the U shape, and connected by 
a liquid drain. The apparatus is commonly used for processing the exhaust 
gas from a semiconductor manufacturing process, and the drain water can 
contain acid and other toxic materials. In this case, the drain water is 
lead to a system for preventing these materials from polluting the 
environment. 
The apparatus has the problem that some of the power is left as a residue 
on the internal components of the apparatus. The apparatus must be partly 
disassembled and the parts must be cleaned to remove the powder deposits. 
More specific features of the apparatus will be described as part of the 
description of a preferred embodiment of the invention. 
SUMMARY OF THE INVENTION 
One object of this invention is to improve and simplify the cleaning of the 
internal parts of the gas processing apparatus. According to our 
invention, a cleaning station is located near the gas processing apparatus 
and preferably is attached to a side wall of the apparatus at a convenient 
height for a person to work at the station while standing. 
The cleaning station includes a water spray for washing the parts, a work 
surface for supporting the parts that are to be cleaned, and an adjoining 
sink that includes a drain that leads to the drain of the gas processing 
apparatus. The cleaning station is mounted on a wall of the enclosure of 
the apparatus in a location where drain connections can be made 
conveniently to the drain system for removing toxic and acid water from 
the cleaning apparatus. The work surface has a side wall that is high 
enough to hold water collected from the spray without interfering with 
manual cleaning of the parts. 
Thus, the invention provides a convenient means for cleaning the parts of a 
gas processing apparatus and it is environmentally safe. Other features of 
the invention will be explained in the description of the preferred 
embodiment.

THE PREFERRED EMBODIMENT 
Introduction--The CDO Apparatus 
As the CDO apparatus is shown in FIG. 1, an exhaust gas enters a system of 
pipes 12 at top left, flows down the left side 13 of the U shape, through 
a connection 14 to the right side 15 of the U shape, and up to an outlet 
16 at top right. In a preferred application for the invention, the exhaust 
comes from a semiconductor manufacturing process (not shown). 
The first section 18 is an oxygenator section (not broken away) where dry 
air is mixed with the exhaust gas. The next section, the thermal reaction 
section 19, has an inner cylindrical part 20 that carries the gas and an 
outer cylindrical part 21 that contains a heater element for heating the 
mixture of gas and oxygen. 
The contaminants in the gas decompose in a thermal process produced by the 
heat and the oxygen. This process produces a powder that is removed from 
the gas in the primary cooling and scrubbing section 24 and the lower 
secondary cooling and scrubbing section 26. The gas then flows upward 
through an upper secondary cooling and demister section, 27. 
Water is sprayed into the primary cooling and scrubbing section 24. A pipe 
28 carries recirculated water to a system of nozzles 29 that spray the 
water into the heated gas. 
Most of the particles of the powder in the gas are trapped by the water 
droplets and is carried to the bottom of the left side 13 where the water 
drains through connection 14 to a drain pipe 31. However, the sudden 
cooling of the powder causes some of it to condense on the walls of the 
cooling section and around nozzles 29. 
Parts of FIG. 1 are broken away to show representative components of the 
primary cooling and scrubbing section 24 that can be removed and then 
cleaned by personnel using the cleaning station of this invention. 
Section 24 also has a helical shaped part 33, called the wiper coil, which 
is one of the parts that is to be cleaned. Part 33 is automatically moved 
up and down to wipe off the powder deposited on the walls. This powder 
drops into the drain 31. 
The secondary scrubbing section 26, shown in a simplified form, also has 
parts that are removable for cleaning. The oxygenator section 18 and the 
upper secondary cooling and demister section 27, also shown in a 
simplified form do not contain parts that are ordinarily removable for 
cleaning. 
Introduction--FIG. 2 
FIG. 2 shows an enclosure 39 for the apparatus of FIG. 1. The exhaust gas 
inlet pipes 12 and the air outlet pipe 16 will be familiar from FIG. 1. 
The enclosure has a base part 40 with rectangular vertical walls (41, 42 
are visible) that enclose the lower part of the apparatus, and it has an 
upper part 44 with rectangular vertical walls (45, 46 are visible). Upper 
part 44 is narrower than base part 40 and the base has a horizontal top 
surface 47. A drip pan 48 surrounds base part 40 for catching any leaking 
water. 
Side wall 45 has an access panel 50 that can be opened to remove parts that 
are to be cleaned and side wall 41 has a removable panel 49 for access to 
other components of the cleaning apparatus. 
A pipe 64 carries water from drain 31 to a drain tank or to a waste 
treatment facility. The base also encloses a drain pump (not shown) that 
pumps waste water into pipe 64. 
The Cleaning Station--FIGS. 2 and 3 
The cleaning station is located near enough to the cleaning process 
apparatus of FIG. 1 that waste water from the cleaning station, which may 
be toxic, can use the drain system of the cleaning process apparatus. 
Preferably, parts of the cleaning station are attached to enclosure 39. 
The cleaning station includes a tray 53 and a sink 54 that are preferably 
mounted on wall 46 of the gas processing apparatus. The tray and sink are 
located at a convenient height for a person to work at the station while 
standing. 
Tray 53 and sink 54 are located over top 47 of the base, and an opening 56 
in top 47 provides an access for a drain pipe 57 from the sink to a tank 
58 that is located in the base 40. 
FIG. 3 shows a typical part 60 located on the tray for cleaning. The 
cleaning station also includes a water spray (conventional and shown as a 
functional box) for washing the parts. 
In FIG. 3 the sink is partly broken away to show a filter 61 with a small 
mesh that is located in the path of water flowing through the sink. (The 
filter is represented schematically.) In summary, the path of wash waste 
water begins at tray 53 and/or sink 54, passes through filter 61 and pipe 
57 to drain tank 58, then to the pump, and then to pipe 64. 
OTHER EMBODIMENTS 
From the description of a preferred embodiment of the invention, those 
skilled in the art will recognize suitable modifications to adapt the 
cleaning station to other apparatus that produces a toxic residue and has 
a system for collecting and processing water containing the type of 
residue that is to be removed at the cleaning station.