Gas separation: processes – Deflecting – And filtering
Reexamination Certificate
2000-07-10
2002-04-09
Spitzer, Robert H. (Department: 1724)
Gas separation: processes
Deflecting
And filtering
C095S287000, C055S324000, C055S327000, C055S332000, C055S350100, C055S497000, C055S501000, C055S521000, C055S528000
Reexamination Certificate
active
06368386
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to air filter systems. In certain applications it concerns air filters for use in the air intake stream of gas turbine systems. In specific applications, it concerns filter constructions applied in gas turbine systems which are constructed to resist passage of moisture and/or salt therethrough. Methods of filtering to achieve such effect are also provided.
BACKGROUND OF THE INVENTION
Although the present invention may be applied in a variety of applications, it was developed for use with gas turbine filter systems. Single stage, self cleaning air filter systems are known. One such system, commercially available, is the Donaldson GDX™ Pulse Cleaning Filter System available from Donaldson Company, Inc., Minneapolis, Minn. In
FIG. 1
, a schematic, cross-sectional, depiction of a Donaldson GDX™ Pulse Cleaning Filter System
20
is presented.
Referring to
FIG. 1
, the system
20
includes a chamber
21
having an air inlet side
22
and an air outlet side
23
. Air enters the chamber
21
through a plurality of vertically spaced inlet hoods
26
positioned along the air inlet side
22
. The inlet hoods
26
function to protect internal filters of the system
20
from the effects of rain, snow and sun. Also, the inlet hoods
26
are configured such that air entering the inlet hoods
26
is first directed in an upward direction indicated by arrow
27
, and then deflected by deflector plates
28
in a downward direction indicated by arrow
29
. The initial upward movement of air causes some particulate material and moisture from the air stream to settle or accumulate on lower regions
30
of the inlet hoods
26
. The subsequent downward movement of air forces dust within the chamber
21
downward toward a dust collection hopper
32
located at the bottom of the chamber
21
.
The chamber
21
of the system
20
is divided into upstream and downstream volumes
34
and
36
by a partition
38
. The upstream volume
34
generally represents the “dirty air section” of the air cleaner system
20
, while the downstream volume generally represents the “clean air section” of the system
20
. The partition
38
defines a plurality of apertures
40
for allowing air to flow from the upstream volume
34
to the downstream volume
36
. Each aperture
40
is covered by an air filter
42
or filter cartridge located in the upstream volume
34
of the chamber. The filters
42
are arranged and configured such that air flowing from the upstream volume
34
to the downstream volume
36
passes through the filters
42
prior to passing through the apertures
40
.
For the particular filter arrangement shown, each air filter
42
includes a pair of filter elements. For example, each air filter
42
includes a cylindrical element
44
and, a somewhat truncated, conical, element
46
. Each truncated, conical element
46
includes one end having a major diameter and another end having a minor diameter. The cylindrical element
44
and the truncated, conical element
46
of each filter
42
are co-axially aligned and connected end-to-end with the minor diameter end of each conical element
46
being secured to one of the cylindrical elements
44
in a sealed manner. The major diameter end of each truncated, conical element
46
is secured to the partition
38
such that an annular seal is formed around its corresponding aperture
40
. Each filter
42
is generally co-axially aligned with respect to its corresponding aperture
40
and has a longitudinal axis that is generally horizontal.
In general, during filtering, air is directed from the upstream volume
34
radially through the air filters
42
into interior volumes
48
of the filters
42
. After being filtered, the air flows from the interior volumes
48
through the partition
38
, via apertures
40
, into the downstream clean air volume
36
. The clean air is then drawn out from the downstream volume
36
, through apertures
50
, into a gas turbine intake, not shown.
Each aperture
40
of the partition
38
includes a pulse jet air cleaner
52
mounted in the downstream volume
36
. Periodically, the pulse jet air cleaner
52
is operated to direct a pulse jet of air backwardly through the associated air filter
42
, i.e. from the interior volume
48
of the filter element outwardly to shake or otherwise dislodge particular material trapped in or on the filter media of the air filter
42
. The pulse jet air cleaners
52
can be sequentially operated from the top to the bottom of the chamber
21
to eventually direct the dust particulate material blown from the filters into the lower hopper
32
, for removal.
Arrangements such as those shown in
FIG. 1
may be rather large. Filter pairs used in such arrangements commonly include cylindrical filters that are about 26 inches long and about 12.75 inches in diameter, and truncated conical filters that are about 26 inches long, about 12.75 inches in minor diameter, and about 17.5 inches in major diameter. Such arrangements might be used, for example, for filtering intake air to a gas turbine system having an air flow demand on the order of 8000 to 1.2 million cubic feet per minute (cfm).
A variety of types of filter elements have been used in arrangements such as that described above with respect to FIG.
1
. Donaldson Company, Inc., for example, markets filter elements under the designation “GDX filter elements” for such systems which comprise pleated paper having a web of submicron diameter fibers applied to a surface thereof, using proprietary, trade secret, Donaldson method, under the designation Spider-Web®.
SUMMARY OF THE INVENTION
One aspect of the present invention relates methods and systems that use hydrophobic media to reduce the concentration or amount of water soluble material such as salt present in the intake air of a gas turbine engine or other type of environment that is sensitive to water soluble materials such as salt.
Another aspect of the present invention relates to a gas turbine intake air filter system including a first stage air cleaner for reducing the concentration of particulate material in the turbine intake air, and a second stage filter arrangement located downstream from the first stage air cleaner. The second stage filter arrangement includes a hydrophobic medium arranged and configured to reduce the concentration of moisture/salt solution in the intake air.
A further aspect of the present invention relates to a barrier arrangement for filtering water soluble material such as salt from an air stream such that the concentration of water soluble material is reduced. The barrier arrangement includes a plurality of vertically spaced-apart hydrophobic filter elements. The barrier arrangement also includes a plurality of inclined baffles arranged and configured to direct the air stream upward through the hydrophobic filter elements. Each of the baffles is positioned beneath a corresponding one of the hydrophobic filter elements. In operation, salt solution accumulates on lower surfaces of the filter elements. The accumulated salt solution drips from the filter elements onto the inclined baffles. The inclination of the baffles causes the salt solution to run downward and drip off upstream edges of the baffles.
An additional aspect of the present invention relates to a gas turbine system including a gas turbine adapted to draw intake air. The system also includes a hydrophobic medium through which the intake air is filtered prior to entering the gas turbine.
Still another aspect of the present invention relates to a method for filtering intake air of a gas turbine. The method includes the steps of filtering particulate material from the intake air at a first stage air cleaner, and directing the intake air downstream from the first stage air cleaner through an air flow gap to a second stage salt barrier. The method also includes the steps of reducing the concentration or level of salt in the intake air at the second stage salt barrier, and directing the intake air downstream from the second stage salt barrier to the gas turbine.
Gogins Mark Alan
Nelson Benny Kevin
Donaldson & Company, Inc.
Merchant & Gould P.C.
Spitzer Robert H.
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