Gas separation – Two or more separators
Reexamination Certificate
1999-12-20
2001-09-18
Simmons, David A. (Department: 1724)
Gas separation
Two or more separators
C055S502000, C055S508000, C055S523000
Reexamination Certificate
active
06290743
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates generally to hot-gas cleanup systems for feed gas to turbines; and more particularly, to a filter assembly for such systems that includes an all metal fail-safe/regenerator filter device, containing an array of individual small porous metal media tubes, or an alternating channel porous structure such as a honeycomb metal media means to trap particulates, eliminating the need for additional heat transfer surfaces as Raschig rings, and screen assemblies as a means of particulate removal. This metal fail-safe/regenerator filter device is attached to a metallic type filter element.
Background Information
Modern industrial methods have resulted in a need for an apparatus that is capable of efficiently filtering high temperature combustion or gasification gases containing particulate material. In combustion turbine applications, for example, a combustion turbine uses energy generated from hot pressurized combustion gases produced by burning natural or propane gas, petroleum distillates or low ash fuel oil. When coal and other solid fuels are burned, particulates carried over from the combustion of such solid fuels can cause turbine blade erosion and fouling. An efficient system for filtering of such hot combustion gases would permit the use of such solid fuels. As another example, in conventional boiler operations, the boilers undergo routine shutdown for cleaning the fireside surfaces and for inspection. An efficient hot gas filtering system would greatly extend the life and operational time for a boiler to operate between inspections. Fouling of the fireside surface due to ash deposition and corrosion would be eliminated or minimized.
Also, as a key component in advanced coal-or biomass-based power applications, hot gas filtration systems protect the downstream heat exchanger and gas turbine components from particle fouling and erosion, cleaning the process gas to meet emission requirements. When installed in either pressurized fluidized-bed combustion (PFBC) plants, pressurized circulating fluidized-bed combustion (PCFBC) plants, or integrated gasification combined cycle (IGCC) plants, lower downstream component costs are projected, in addition to improved energy efficiency, lower maintenance, and elimination of additional expensive fuel or flue gas treatment systems. As a critical component, long-term performance, durability, and life of the filter elements and associated high temperature gasket seals are essential to the successful operation of hot gas filtration systems in advanced combustion and gasification applications.
U.S. Patent Nos. 5,185,019; 5,433,771 and 5,876,471 (Haldipur et al.; Bachovchin et al. and Lippert et al., respectively), teach improved gasket assemblies that can be employed with conventional or thin-walled ceramic candle filters. All three show separate holders/chambers for fail-safe regenerator units. Bachovchin et al. teach a combination of four metal screens in combination with a bed of particles, such as stainless steel Raschig rings, as shown in FIG.
6
. Fine screens trap particulate matter within the unit and prevent the collected particulate matter from being liberated during reverse cleaning pulsation. The Raschig rings form a thermal regenerator which heats pulses of cold gas during reverse flow cleaning. Lippert et al. in their
FIG. 4
show another such fail-safe/regenerator device which is permanently mounted within a filter housing having associated gaskets, in contact with a ceramic candle filter. The fail-safe/regenerator similarly prevents particulate matter from traveling into the clean gas area of the pressure vessel if a ceramic filter element fails. Additionally, U.S. Ser. No. 09/263,436, filed on Mar. 4, 1999, now U.S. Pat. No. 6,123,746, provided an improved gasketing assembly, with an optional fail-safe/regenerator, and described possible use of metallic filter elements having the same connection and configuration as standard ceramic candle filters, and U.S. Ser. No. 09/393,561 filed on Sep. 10, 1999 teaches all metal filter configuration with reduced use of gaskets, and an integral filter fail-safe/regenerator device similar to Bachovchin et al.
While these inventions provide advances in the art, enhanced particulate capture capabilities beyond screens and Raschig rings are needed, as well as the ability of any new assembly to be retrofit into existing filter systems. Also, even more efficient heat transfer is needed during filter assembly cleaning operations.
Besides these specific type candle filters, others have provided honeycomb structures used as filters, as taught in U.S. Patent application Ser. Nos. 4,364,760; and 5,069,697 (Higuchi et al., and Hamaguchi et al., respectively). These structures have parallel channels through the body with half being sealed at one end and the other half sealed at the other end, for use to trap dust from gas on Diesel engines. These patents define the “honeycomb” structure in the filter art.
There is still a need to develop higher reliability filter configurations for use in advanced coal-fired operation applications. There is also a need for improved heat transfer from incoming cold gas flowing into the filter elements during back pressure cleaning of the filter elements. Finally, it would be desirable that any improved filter assembly be able to substitute into existing systems in the field.
SUMMARY OF THE INVENTION
Therefore, it is a main object of this invention to provide an improved fail-safe/regenerator filter device having improved filtering capability and which is resistant to sulfur, alkali, chlorides, steam and other contaminants found in coal gas streams.
It is a further object to improve heat transfer efficiency of the fail-safe/regenerator during cleaning operations and provide a design that can easily substitute into existing units.
These and other objects are accomplished by providing a filter assembly for filtering gas, comprising a fail-safe/regenerator filter device and an elongated filter element, within a hot gas cleanup system pressure vessel having a hot contaminated gas entry, said filter assembly comprising: a filter housing, said filter housing having a peripheral sidewall, said sidewall defining an interior chamber; a porous, elongated filter element body attached to the bottom end of the fail-safe/regenerator filter device; and a one-piece, all metal, fail-safe/regenerator filter device, having a top and bottom end, disposed within the interior chamber of the filter housing; said fail-safe/regenerator filter device containing a metal support attached to a plurality of, porous elongated passageway members selected from: 1) elongated tubes having a bottom end with openings, and 2) honeycomb members having a bottom end with openings and a plurality of parallel passageways with alternating passageways being sealed at the top end and the bottom end, with the open bottom ends facing the filter element. The passageways thus are either a tubular or honeycomb cartridge. This fail-safe/regenerator filter device preferably eliminates the use of Raschig rings, metal screens and the like, and the porous walls of the gas passageways provide high surface area not only to heat the incoming pulse gas, but also to trap minute particulate matter.
The invention also resides in a candle or tube filter holder and gasket assembly for holding a candle or tube filter element within a hot gas cleanup system pressure vessel, the filter element including a body having opposing ends, one defining a flange open end and the other defining a closed end; the filter element body having a smaller inner diameter surface and a larger outer diameter surface, said candle or tube filter holder and gasket assembly comprising: (a) a filter housing, said filter housing having a peripheral sidewall, said sidewall defining an interior chamber; (b) a filter element selected from the group consisting of a porous monolithic ceramic matrix, a filament wound ceramic matrix, a continuous fiber ceramic composite matrix, or a metal or interme
Alvin Mary Anne
Bruck Gerald J.
Lippert Thomas E.
Smeltzer Eugene E.
Hopkins Robert A.
Siemens Westinghouse Power Corporation
Simmons David A.
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