Gas separation – Deflector – Plural deflectors overlapped and spaced serially in gas flow
Reexamination Certificate
1999-12-23
2001-09-18
Spitzer, Robert H. (Department: 1723)
Gas separation
Deflector
Plural deflectors overlapped and spaced serially in gas flow
C055S465000, C055SDIG007
Reexamination Certificate
active
06290742
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an improved baffle system for separating entrained liquids from a gas stream having improved efficiency.
BACKGROUND OF THE INVENTION
Baffle systems for separating liquid entrained in a gas stream have been used for many years. For example, baffle systems are conventionally used for separating water from an air stream in a paint application system. The paint overspray is washed from the paint application booth with water or a water emulsion. The water and paint overspray is then received through scrubbers generally located in the floor below the paint application booth. The gas scrubber removes paint particles from the air in the paint booth, entraining the paint particles in the liquid. The air stream is then passed through baffles, removing the entrained liquid from the air stream.
A common form of baffle used by the automotive industry in paint application systems, for example, comprise at least two columns of U-shaped rectangular vertical baffles. The baffles each include a web portion and perpendicular flange portions, such that the web portions of the first column of baffles faces the direction of the air flow and the second column of baffles overlaps the baffles in the first column with the flanges extending toward the direction of air flow. The baffle system thus requires the gas stream to flow around the web portions of the first column of baffles into the rectangular U-shaped baffles of the second column of baffles and around the flange portions of the second column of baffles, depositing the liquid on the baffles which flows downwardly and out of the system. The particle size of the liquid droplets or particles is generally greater than one micron (1 &mgr;m). In a conventional baffle system of this type, the width of the web portion is eight inches, the length of the flange portions are four inches and the flange portions overlap 0.25 inches. The average face velocity measured parallel to the duct in a baffle system for a paint application system of this type is generally between one hundred fifty to three hundred fifty feet per minute (fpm). The problem with baffle systems of this type is poor efficiency. That is, less than about fifteen percent of the entrained liquid is removed from the gas stream.
Various attempts have been made to improve the efficiency of baffle systems for removing entrained liquid from a gas stream. For example, the velocity of the gas stream through the baffle system may be increased by overlapping the ends of the flange portions, thereby improving the efficiency of the baffle system. However, a liquid having entrained paint particles will collect between the overlapping flanges requiring more frequent maintenance. It is also more difficult to clean between the overlapping flanges. More importantly, overlapping flanges provide only a very limited improvement in efficiency, generally not exceeding two or three percent. Other proposed attempts to improve the efficiency of baffle systems for removing entrained liquid from a gas stream include complex baffle systems including, for example, spiral baffles, baffles having hook-shapes which further increase the velocity of the gas stream through the baffles to improve efficiency, etc. However, such complex baffle systems are relatively expensive to manufacture and require frequent maintenance particularly where a tacky substance, such as paint, is entrained in the liquid droplets or particles. Such complex baffle systems have not been found suitable for removing liquid entrained in a gas stream in a paint application system.
Thus, there remains a long-felt need for an improved baffle system which is relatively simple in construction, low in cost and having improved efficiency. Further, there is a need to reduce the maintenance costs of conventional baffle systems which reduces the collection of liquid and entrained tacky particles and which is easily cleaned, if necessary. As described below, the improved baffle system of this invention is relatively simple in construction, having reduced costs, particularly when compared to the complex baffle systems described above, and the baffle system of this invention has reduced maintenance costs when compared to baffle systems having overlapping elements.
SUMMARY OF THE INVENTION
The baffle system of this invention is generally conventional in construction. However, it has been discovered that it is possible to significantly improve the efficiency of the baffle system by modifying the proportions and size of the baffle elements as set forth below. The baffle system of this invention includes a plurality of generally coplanar columns of baffle members, wherein the web portions of the baffle members of the first column overlap the web portions of the baffle members of the second column. The baffles are generally U-shaped, wherein the flange portions extend generally perpendicular to the web portions. Although the preferred embodiment of the baffles are generally rectangular having planar web portions and perpendicular planar flange portions for simplicity of construction and low cost, it will be understood that the web and flange portions may take various shapes and the flange portions may extend from the web portion at an angle other than ninety degrees. Conventionally, the web portion of the first column of baffles face the gas stream and the baffles of the second column open toward the gas stream with the flange portions extending toward the web portions of the adjacent first column of baffles. Further, the web portions of the first and second column of baffles overlap, such that the gas stream flows over the web portions of the first column of baffles into the open baffles of the second column and around the flange portions of the second column as described above.
As set forth above, the applicants have discovered that the liquid removal efficiency of baffle systems of this type may be increased by simply increasing the width of the web portions relative to the length of the flange portions and/or decreasing the overall size of the baffles. It is also possible to further increase the efficiency of the baffle system of this invention by including small opposed lips at the free end of the flange portions, although this improvement may result in increased maintenance over a rectangular U-shaped baffle. The width of the web portion is at least three times greater than the length of the flange portions or preferably three to ten times the length of the flange portions. In a more preferred embodiment, the width of the web portions of the baffle members is four to eight times the length of the flange portions or most preferably four to six times the length of the flange portions wherein the web portion is two to six inches. As described above, in a conventional baffle system of this type, the width of the web portion is eight inches and the length of the flange portion is four inches with an overlap between the opposed flange portions of approximately 0.25 inches. The efficiency of the baffle system of this invention is further improved by reducing the width of the web portion to six inches or less, more preferably five inches or less and most preferably four inches or less. In certain applications the opposed flange portions of the adjacent columns of baffles may overlap. However, in the preferred embodiment for applications wherein the entrained liquid includes a tacky substance such as paint particles, the flange portions do not overlap, significantly reducing maintenance costs. In the preferred embodiment of the baffle system of this invention, the distance between the web portions of the adjacent columns of baffle members is between about 0.3 to 0.7 of the width of the web portions or more preferably about one half the width. Further, the angle defined between the web portions and the direction of flow of the gas stream is between ninety degrees and one hundred thirty-five degrees.
Surprisingly, the efficiency of the baffle system of this invention may approach one hundred percent or four to five fold over a
Pakkala James L.
Still Gregory M.
Yu Guang
Durr Industries, Inc.
Howard & Howard
Spitzer Robert H.
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