Furnaces – Fuel feeders – Blower
Reexamination Certificate
1999-11-03
2001-05-22
Ferensic, Denise L. (Department: 3749)
Furnaces
Fuel feeders
Blower
C110S10400A, C110S218000
Reexamination Certificate
active
06234090
ABSTRACT:
FIELD OF THE INVENTION
The present invention is in the field of equipment for producing evenly distributed flows of dust-like coal fines from a coal mill to a power-plant type combustion chamber through one or more delivery pipes.
BACKGROUND OF THE INVENTION
Coal-fired combustion chambers of the type used in power-generating plants burn dust-like coal fines which are ground or pulverized by an on-site coal mill. It is critical to deliver even, distributed flows of coal fines to the multiple burners in the combustion chamber to prevent “rich” areas in the combustion chamber which produce LOI (loss on ignition) particles; “lean” areas which promote NOX formation; elliptical fireballs, which create uneven heating and fireball impingement on the boiler tube “water walls”; coal falling out of suspension in the delivery pipes, causing spontaneous combustion fires and risk of explosion; and, fireball backup in “light flow” burners, which can seriously damage them.
One prior art device which attempts to provide evenly distributed flows of coal among multiple pipe branches on the way to the burners is the “riffle box”, typically a series of alternately-angled plates or bars placed at each branching of the pipes in an attempt to redistribute the heavy and light coal flows or “ropes” which often develop across the delivery pipe. Schematic examples of riffles boxes are shown in FIG.
1
.
Riffle boxes have generally been found to be unsuccessful in creating evenly distributed flows of coal in the downstream pipe branches. A significant improvement over riffle box type devices is found in co-pending U.S. application Ser. No. 08/987,646, co-owned with the present application. That application discloses a device which causes heavy and light flows of coal distributed across a pipe to converge upon one another, preferably upstream of the riffle box, causing them to implode and be evenly distributed across the width of the pipe. This device has been found to be particularly useful for round, large-diameter delivery pipes. It is, however, somewhat difficult to fit to rectangular conduits because it requires upstream and downstream rectangular-to-round adapters.
SUMMARY OF THE INVENTION
The present invention is a device for diffusing coal flow into an even distribution across a delivery pipe, resulting in even flow through all downstream pipes and burners, generally comprising a plurality of toothed, linear diffuser elements mounted laterally across the width of a delivery pipe. The invention can be used in both round and rectangular pipes, but is considered to be particularly useful for rectangular-conduit pipe.
There are two basic embodiments of the invention: a set of linear static diffuser elements comprising fixed, toothed, laterally-placed elements mounted across the width and/or about the periphery of the delivery pipe; and, one or more linear, rotating diffuser elements placed laterally across the delivery pipe and rotatingly adjustable (either by hand to a fixed position or continuously rotating by motor).
The linear diffuser elements can be built directly into a section of existing delivery pipe or, in a preferred form, are built into a housing which mimics the cross section of the delivery pipe and can be placed in line with the pipe, either between two sections or by cutting out part of the existing pipe and inserting the housing.
The “teeth” of the diffuser elements may be pointed, square, or round, but are preferably of alternating height across the length of the diffuser element to break the segregated coal flow into a diffused, evenly distributed (random) pattern. In general larger “teeth” or protrusions are used for denser, heavier regions of flow within the conduit.
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Nardi John Anthony
Wark Rickey E.
Ferensic Denise L.
Rinehart Kenneth B.
Sure Alloy Steel Corporation
Young & Basile P.C.
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