Power plants – Combustion products used as motive fluid – With safety device
Reexamination Certificate
2003-01-08
2004-07-27
Kim, Ted (Department: 3746)
Power plants
Combustion products used as motive fluid
With safety device
C055S385300, C055S485000, C055S489000
Reexamination Certificate
active
06766636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas turbine intake air filter unit, more specifically to improving technique of a filter unit for efficiently collecting dust contained in outside air aspirated into a gas turbine.
2. Description of the Related Art
As is popular in the industry, a gas turbine is provided with an intake air filter unit at an upstream side end portion of an intake duct communicating with an internal area of the gas turbine, for collecting fine dust contained in outside air aspirated by an air compressor. Since it has been a conventional understanding that operation of the air compressor would not be seriously disturbed provided that the intake air filter unit is capable of collecting dust of a particle diameter of approx. 5 &mgr;m or larger, a two-stage intake air filter unit having two filter layers has conventionally been employed.
However, in such two-stage intake air filter unit, minute dust of a particle diameter of for instance less than 1 &mgr;m that can pass through the filter layers adheres to a vane of the air compressor, leading to lower performance of the air compressor and further to a substantial output loss of the gas turbine, and resultantly the gas turbine cannot satisfy current demand for a high output. Employing filter layers having a higher collecting efficiency in the two-stage intake air filter unit could be a solution of the problem, however such a simple measure only causes disadvantages such as a shorter life span of the filter layers and need for frequently replacing the filter layers in short intervals. Besides, when replacing the filter layers operation of the gas turbine must be suspended in order to prevent intrusion of dust into inside the gas turbine, therefore availability factor of the gas turbine inevitably becomes lower.
Accordingly, as disclosed in JP-A No.7-253028, recently a three-stage intake air filter unit having three filter layers has been proposed, and has come to be put to trial. The filter unit disclosed in this Publication comprises a primary filter layer constituted of a panel type demister and a rolled strap type or streamer type prefilter, a secondary filter layer constituted of medium performance filters and a tertiary filter layer constituted of high performance filters, sequentially aligned from an upstream side in a direction of intake air flow.
In this case the panel type demister comprises unitary demisters formed into a plate shape by coating and bonding with a binder a multitude of small elastic bodies made of animal and vegetable fibers curled into a spring shape, and four rows of four pieces each, totally 16 pieces of such unitary demisters are disposed inside a casing located at an upstream side end portion of the intake duct.
Also, the rolled strap type and the streamer type prefilter are unitary filters made of a glass fiber or organic fibers such as acrylic fiber etc. The rolled strap type prefilter comprises a strap-shaped fiber filter medium spanned between a pair of rolls on which the fiber filter medium can be rolled, while the streamer type prefilter comprises a multitude of bags disposed in parallel close to one another with the respective openings fixed to a frame, and four rows of four pieces each, totally 16 pieces of either of such prefilters disposed inside the casing constitute the primary filter layer.
Further, the medium performance filter and the high performance filter are unitary filters comprising a high efficiency filter medium and a low efficiency filter medium closely layered, bent in zigzags with the projections and recesses thereof aligned with a direction of intake air flow and then set in a box, and four rows of four pieces each, totally 16 pieces of such unitary filters disposed at two positions inside the casing respectively constitute the secondary filter layer and the tertiary filter layer.
With respect to the foregoing three-stage intake air filter unit, in all of the primary filter layer, secondary filter layer and tertiary filter layer, the prefilters, medium performance filters and high performance filters that are the unitary filters of the respective filter layers are disposed on a plane that is orthogonal to a direction of intake air flow inside the intake duct, as shown in
FIG. 1
of the aforementioned Publication.
More specifically, in the primary filter layer totally 16 pieces of the rolled strap type or streamer type prefilters are disposed on an identical plane, in the secondary filter layer totally 16 pieces of the medium performance filters are disposed on an identical plane, and in the tertiary filter layer totally 16 pieces of the high performance filters are disposed on an identical plane.
Under such configuration wherein the unitary filters are disposed on a plane in all of the filter layers, however, when the filter layers are increased from two stages to three stages, flow resistance hence pressure loss of the intake air passing through the tertiary filter layer may become unreasonably great because of insufficient intake air passing area of the tertiary filter layer, thereby disturbing smooth flow of the intake air and resultantly causing driving loss of an air compressor.
Accordingly a balance of collecting efficiency of the tertiary filter layer and intake air flow resistance becomes a critical issue to be explored, however at present development of an intake air filter unit focused on optimization of such balance has not yet been achieved, because of which such problems as adherence of minute dust to an air compressor and reduction of life span of filters and so forth have not been effectively solved.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is a technical object of the present invention to provide a gas turbine intake air filter unit, wherein flow resistance of intake air passing through a tertiary filter layer does not become unreasonably great despite the filter layers are increased from two stages to three stages, and a balance of collecting efficiency of the filter layers and the intake air flow resistance is optimized.
In order to solve the foregoing technical problem, the invention provides a gas turbine intake air filter unit, comprising a primary filter layer, a secondary filter layer, and a tertiary filter layer placed at an upstream side end portion of an intake duct that leads intake air into an internal area of a gas turbine and sequentially aligned from an upstream side; wherein the primary, secondary and tertiary filter layers respectively include a plurality of unitary filters; and the plurality of unitary filters of the tertiary filter layer are aligned in such a manner that at least a recess is formed toward a downstream side of the intake air flow.
Under such constitution, since the plurality of unitary filters in the tertiary filter layer are disposed so as to include at least a recess toward a downstream side of the intake air flow, intake air passing area is increased in proportion to the area of the recessed portion. Accordingly, increase of flow resistance, hence pressure loss of the intake air through the tertiary filter layer is properly restrained, therefore smooth flow of the intake air is secured and driving loss of the air compressor is prevented. Moreover, a balance of collecting efficiency of the three filter layers and the intake air flow resistance becomes extremely favorable, therefore adherence of minute dust to the air compressor and reduction of life span of filter layer can be effectively avoided. In addition, since the recess is formed in a direction of downstream side of the intake air flow, there is no likelihood of interference with the secondary filter layers located at an upstream side of the tertiary filter layer, and an optimum layout of the three filter layers can be maintained.
In this case, it is preferable that a downstream side end portion of the recess is located at an upstream side of a wind velocity reference line serving as an index of whether or not a turbulent flow of intake air causes noise and/or vibration. He
Dougahara Mitsuru
Shingu Noriya
Takashima Hidemasa
Yoshitake Shigeru
J.C. Patents
Kim Ted
The Kansai Electric Power Co. Inc.
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