U.S. patent application number 10/288099 was filed with the patent office on 2004-05-06 for sintered metal fiber liner for gas burners.
Invention is credited to Kendall, Robert M., Sullivan, John D..
Application Number | 20040083734 10/288099 |
Document ID | / |
Family ID | 32175831 |
Filed Date | 2004-05-06 |
United States Patent
Application |
20040083734 |
Kind Code |
A1 |
Kendall, Robert M. ; et
al. |
May 6, 2004 |
Sintered metal fiber liner for gas burners
Abstract
An improved liner for gas burners used to confine combustion in
a compact zone adjacent the burner face is formed of a porous sheet
of sintered metal fibers. The novel liner features uniform flow
therethrough of air and provides improved insulation in that the
escape of heat from the combustion zone through the liner is
curtailed. Structural simplicity is another advantage of the new
liner.
Inventors: |
Kendall, Robert M.;
(Sunnyvale, CA) ; Sullivan, John D.; (Fremont,
CA) |
Correspondence
Address: |
PAUL W. GARBO
48 Lester Avenue
Freeport
NY
11520
US
|
Family ID: |
32175831 |
Appl. No.: |
10/288099 |
Filed: |
November 5, 2002 |
Current U.S.
Class: |
60/752 |
Current CPC
Class: |
F23R 2900/03041
20130101; F23M 2900/05004 20130101; F23R 3/002 20130101 |
Class at
Publication: |
060/752 |
International
Class: |
F23R 003/42 |
Claims
What is claimed is:
1. A combustor liner comprising a porous sheet of sintered metal
fibers which faces and confines combustion from a combustor.
2. The combustor liner of claim 1 wherein the porous sheet of
sintered metal fibers is bonded to a perforated metal sheet, the
perforations of which cover at least 80% of the area of said
sheet.
3. The combustor liner of claim 1 wherein the metal fibers are
fibers of an alloy selected from the group consisting of iron-based
or nickel-based alloys containing chromium, and alloys containing
iron, chromium and aluminum.
4. The combustor liner of claim 1 wherein the portion of the liner
near its exit end is perforated.
5. The combustor liner of claim 1 wherein the porous sheet of
sintered metal fibers is formed of two layers of fibers of
different metal compositions.
6. The combustor liner of claim 5 wherein one layer of fibers have
a metal composition selected from the group consisting of
iron-based or nickel-based alloys containing chromium, and alloys
containing iron, chromium and aluminum.
7. The combustor liner of claim 3 wherein the porous sheet of
sintered metal fibers is bonded to a perforated metal sheet, the
perforations of which cover about 95% of the area of said
sheet.
8. The combustor liner of claim 4 wherein the porous sheet of
sintered metal fibers is about 2 millimeters thick.
9. The combustor liner of claim 8 wherein the portion of the liner
near its exit end is perforated.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a liner for gas burners. More
particularly, the invention provides a liner for gas burners used
to maintain combustion in a compact zone while permitting the flow
of air along the outer side of the liner as well as through the
liner into the combustion zone. Liners are especially used with gas
burners of gas turbines.
[0002] Metal liners for gas burners have long been used
particularly in the operation of gas turbines. For example, U.S.
Pat. No. 4,311,447 to Rackley et al shows a metal liner surrounding
a radiant surface combustor, the term commonly used in lieu of gas
burner by the gas turbine industry. U.S. Pat. No. 6,199,364 to
Kendall et al discloses not only several burners with individual
metal liners but also several burners within a pair of liners.
Metal liners frequently have multiple openings so that air flowing
along the outer surface also enters the combustion zone confined by
the liner. U.S. Pat. No. 6,453,672 of Kendall et al illustrates two
types of metal liners: a louvered liner and a backside-cooled
liner. The prior art indicates that a consensus has not been
reached regarding the best metal liner.
[0003] A principal object of this invention is to provide an
entirely new type of liner for gas burners (combustors).
[0004] Another important object is to provide liners of simple form
that permit the flow of air substantially uniformally through all
of the surface of the liners.
SUMMARY OF THE INVENTION
[0005] Basically, the liner of the invention is formed of a porous
sheet of sintered metal fibers that are resistant to the
temperature and oxidizing conditions of the combustion zone
confined by the liner.
[0006] U.S. Pat. No. 5,326,631 to Carswell discloses that fibers
made of an iron-based or nickel-based alloy containing chromium are
suitable for exposure to the conditions of the combustion zone.
U.S. Pat. No. 4,597,734 to McCausland et al mentions an alloy
containing iron chromium and aluminum.
[0007] The porous sheet of sintered metal fibers is formed by
initially laying a fiber pad from an air or liquid dispersion of
the fibers. The fiber pad is then mechanically compressed, usually
by rolling, into a dense but porous sheet that is finally
sintered.
[0008] If greater porosity is desired in some portions of the liner
of this invention, the porous sheet of sintered metal fibers used
to form the liner may have perforated areas. U.S. Pat. No.
5,439,372 to Duret et al teaches such porous sheets of sintered
metal fibers having dual porosities.
[0009] The porous sintered metal fiber liner of this invention may
be provided with a reinforcing metal backing in the form of a
perforated metal sheet. Such reinforcement makes it possible to
minimize the thickness of the porous sintered metal fiber liner and
thus replace costly alloy fibers with common sheet metal.
Preferably, the porous metal fiber liner is sintered to the
perforated sheet metal used as reinforcement. Preferably, the
perforations in the reinforcing metal sheet occupy at least 80% of
the area of the sheet. Most preferably, the perforations of the
reinforcing metal sheet occupy about 95% of the area of the sheet.
The reinforced liner of the invention is used with the metal fiber
side directly exposed to the combustion confined by the liner.
[0010] Another way of economizing on the alloy fibers that are
exposed to combustion involves forming the porous fiber liner as
two layers: one layer of inexpensive metal fibers and another layer
of metal fibers selected for resistance to combustion conditions.
The latter layer would face the combustion zone. The two fiber
layers would be compressed into a unitary sheet and sintered to
yield the porous fiber liner of this invention.
[0011] The porous sheet of sintered metal fibers used to form a
liner for combustors achieves a uniformity of air flow therethrough
into the combustion zone not attained by any prior liner. In
addition to this advantage, the sintered metal fiber liner provides
a better insulating effect against heat flow from the combustion
zone. A metal sheet of the same thickness as a porous sheet of
sintered metal fibers is a much better heat conductor; in short,
the porosity of sintered metal fibers acts as insulation.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0012] As an example of the invention, a 2 millimeter thick porous
sheet of sintered metal fibers purchased from N.V. Acotech S.A. of
Zwevegem, Belgium, is bent and shaped as a liner. The edges of the
porous sheet that are abutted to close the liner are spot-welded
together to complete the simple formation of the novel liner. The
portion of this liner near the exit end of the combustion zone is
preferably perforated, similar to the manner shown in the
aforementioned Duret et al patent, to increase the flow of air into
the hot gases leaving the combustion zone. Perforations with
diameters of about 0.050 to 0.075 inch are generally preferred.
[0013] Those skilled in the art will visualize variations and
modifications of the invention in light of the foregoing teachings
without departing from the spirit or scope of the invention.
Accordingly, only such limitations should be imposed on the
invention as are set forth in the appended claims.
* * * * *