Gas separation: processes – Filtering – With cleaning of filter
Reexamination Certificate
2001-04-20
2003-08-05
Smith, Duane (Department: 1724)
Gas separation: processes
Filtering
With cleaning of filter
C095S281000, C095S282000, C096S231000, C096S233000, C055S292000, C055S304000, C055S495000, C055S497000, C055S500000, C055S521000, C055S528000
Reexamination Certificate
active
06602328
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas turbine suction air filter, a gas turbine using this filter and a method for using this filter.
2. Description of the Prior Art
A gas turbine generally comprises an air suction portion, a compressor, a combustor and a turbine portion. Air is taken from the air suction portion and is supplied into the compressor to be compressed. The compressed air is sent to the combustor. In the combustor, the compressed air and fuel are mixed together to be burned continuously. By the combustion, a high temperature, high pressure combustion gas is generated to be supplied into the turbine portion. By expansion of the combustion gas, moving blades of the turbine portion are driven to rotate a rotor and thereby to generate an electric power.
If foreign matters, such as dust, is included in the air to be supplied into the compressor, the foreign matters attaches to the blades of the compressor to thereby reduce the compression efficiency. Thus, in order to remove the foreign matters, the air is filtered at the air suction portion. Usually, the air suction portion is provided with a first filter portion, which is constructed by a multiplicity of juxtaposed coarse dust filters, a second filter potion, which is constructed by a multiplicity of juxtaposed medium and high performance filters, and a third filter portion which is constructed by a multiplicity of juxtaposed ultra-high performance filters. With these filter portions, dust is removed. It is to be noted that, in some gas turbines, the third filter portion is ommitted.
As clogging occurs in each of the filters after long term use, the filter must be replaced. It is the present situation that the coarse dust filter is replaced at an interval of about three months, the medium and high performance filter at an interval of about 6 to 12 months and the ultra-high performance filter at an interval of about 12 months. The filter, after use, is disposed as industrial waste.
As the gas turbine consumes a large volume of air, a multiplicity of filters are needed. For example, in a usual gas turbine, the first filter portion, the second filter portion and the third filter portion, have some hundreds of filters therein, and each of the filters has an opening area of about 0.35 m
2
. Therefore, in every case of the replacement, a large quantity of industrial waste is discharged. This causes a problem from the viewpoint of the environment preservation. Also, it is not preferable, from the point of view of resource savings, to use such a large quantity of filters This invites an increase in the running cost of the gas turbine.
In view of the above mentioned problems, trials are been done recently to wash the filter after used for reuse thereof. For the washing, an ultrasonic washer is most appropriate. In the ultrasonic washer, cavitations are generated by an ultrasonic wave. When these cavitations disappear, impulse forces are generated and the dust attached to the filter cloth is thereby removed.
FIG. 5
is a partial cross sectional view of one prior art example of a medium and high performance filter
51
which is used in the air suction portion. In
FIG. 5
, air comes from the direction of arrow A and passes through the filter
51
. The filter
51
comprises a multiplicity of separators
53
which are made of aluminum or the like. Each of the separators
53
is formed in a corrugated shape and extends perpendicularly to the plane of
FIG. 5. A
filter cloth
55
, which is made of a glass fiber non-woven fabric or the like, is provided between each of the separators
53
. The filter cloth
55
is arranged in a serpentine form so as to alternately pass right hand ends and left hand ends of the separator
53
. By this arrangement, area of the filter cloth
55
, which is also an air passing area, becomes larger and the dust collection efficiency is enhanced.
As the gas turbine consumes a large volume of air, as described above, the multiplicity of filters
51
are used in the air suction portion. For this reason, the air suction portion becomes extremely large. Thus, the gas turbine needs a wide installation space and construction costs becomes high. In order to mitigate this problem, in the filter
51
for the gas turbine, as compared with general filters, such as those for air conditioning in a building, a pitch P, as shown in
FIG. 5
, between each of the separators
53
is made smaller. Hence, the air passing area becomes large, the number of filters
51
to be used for the air suction portion is reduced, and a smaller size of the air suction portion is thereby attained.
For example, while the separator pitch in the general filter is 10 to 15 mm, the separator pitch P in the filter
51
for the gas turbine air suction portion is about 5 mm. By this arrangement, while the capacity, or the air passing volume per filter, of the general filter is 35 to 50 m
3
/minute, that of the gas turbine air suction portion attained is as high as about 50 to 70 m
3
/minute.
However, even though the filter
51
in which the separator pitch P is made smaller is washed by an ultrasonic washer, transmission of the ultrasonic wave is obstructed by the separator
53
, so that the ultrasonic wave hardly reaches the entire portion of the filter cloth
55
, and there is a problem in that the dust is not sufficiently removed. This problem makes the reuse of the filter
51
for the gas turbine air suction portion difficult as compared with a general filter.
Also, as mentioned above, the prior art filter
51
for use in the gas turbine suction air portion, after use, is disposed as industrial waste, not to be reused. This increases the running cost of the gas turbine having the air suction portion mounted with the filter
51
.
SUMMARY OF THE INVENTION
In view of the mentioned problems in the prior art, it is an object of the present invention to provide a gas turbine suction air filter and a method for using the same by which a large capacity is realized and dust can be still be easily removed by an ultrasonic washer. Also, it is another object of the present invention to provide a gas turbine in which the filter of the present invention is used.
In order to achieve the mentioned objects, the present invention provides a gas turbine suction air filter comprising a frame member having an air passing cross section formed in a rectangular shape and a filter cloth contained in the frame member. The filter cloth is folded so that a multiplicity of folded faces may be formed along an air passing direction and adjacent ones of the folded faces directly confront each other with only a space being arranged therebetween.
In the mentioned filter, as the filter cloth is folded so that the multiplicity of the folded faces may be formed along the air passing direction, the air passing area is large and hence the capacity is large. Also, in this filter, as the adjacent ones of the folded faces directly confront each other with only a space being arranged between them, and no intervening member, such as a separator, is provided between adjacent ones of the folded faces, the ultrasonic wave reaches to the entire filter cloth. Thus, sufficient dust removal can be attained by the ultrasonic washer.
It is preferable that the frame member constituting the mentioned filter of the present invention is made of a metal material.
In the metal material, the ultrasonic wave transmission is damped less. Also, as the metal material is excellent in the strength and rigidity, the thickness of the frame member can be made smaller as compared with a frame member constructed of a wooden material, a synthetic resin or the like. That is, in the frame member of the filter of the present invention, less damping of the ultrasonic wave is effected not only for the reason of the material, but also because of the thickness of the member. Thus, in this filter, even though the air passing area is large, the ultrasonic wave easily reaches to the entire filter cloth. This metal frame member is appropriate for use in the filter of a
Adachi Tatsuo
Aota Toyosei
Doi Yoshiyuki
Hara Satosi
Isohasi Kenji
Greene Jason M.
Mitsubishi Heavy Industries Ltd.
Smith Duane
Wenderoth , Lind & Ponack, L.L.P.
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