TECHNICAL FIELD
[0001] Embodiments of the invention relate generally to firing systems
for use with pulverized solid fuel burners, and more specifically, to an adjustable
nozzle tip for use in such firing systems.
10
DISCUSSION OF ART
[0002] Systems for delivering pulverized solid fuel (e.g., coal) to steam
generators typically include a plurality of nozzle assemblies through which the
pulverized coal is delivered, using air, into a combustion chamber of the steam
15 generator. The nozzle assemblies are typically disposed within windboxes, which
may be located proximate to the corners of the steam generator. Each nozzle
assembly includes a nozzle tip, which protrudes into the combustion chamber.
Each nozzle tip delivers a single stream, or jet, of the pulverized coal and air into
the combustion chamber. After leaving the nozzle tip, the single pulverized
20 coal/air jet disperses in the combustion chamber.
[0003] Typically, the nozzle tips are arranged to tilt up and down to adjust
the location of the flame within the combustion chamber. The flames produced at
each pulverized solid fuel nozzle are stabilized through global heat-and masstransfer processes. Thus, a single rotating flame envelope (e.g., a “fireball”),
25 centrally located in the furnace, provides gradual but thorough and uniform
pulverized solid fuel-air mixing throughout the entire furnace.
[0004] Although the pulverized solid fuel nozzle tips of the prior art are
operative for their intended purposes, there has nevertheless been evidenced in the
prior art a need for such pulverized solid fuel nozzle tips to be further improved,
30 specifically in the pursuit of greater durability and service life. In particular,
existing nozzle tips are ceramic castings which can be damaged by extremely high
temperatures within the combustion chamber and/or by impacts from falling slag.
[0005] In view of the above, there is a need for a pulverized coal nozzle tip that is
more durable and has a longer service life than existing nozzle tips.
35
BRIEF DESCRIPTION
3
[0006] In an embodiment, a nozzle tip for a pulverized solid fuel pipe
nozzle of a pulverized solid fuel-fired furnace is provided. The nozzle tip
includes an inner nozzle portion and an outer nozzle portion that receives therein
the inner nozzle portion. The outer nozzle portion has a lower supporting surface
5 that is configured to support a lower surface of the inner nozzle portion. The
outer nozzle portion also includes a plurality of ribs that define therebetween a
plurality of flow passages for the passage of air. The ribs, in addition to define the
airflow passages, provide bolstering support for the lower supporting surface. The
outer nozzle portion is formed from stainless steel.
10
DRAWINGS
[0007] The present invention will be better understood from reading the
following description of non-limiting embodiments, with reference to the attached
drawings, wherein below:
15 [0008] FIG. 1 is a diagrammatic representation of a vertical sectional view
of a pulverized solid fuel-fired furnace embodying a firing system with which a
solid fuel nozzle tip construction in accordance with the invention may be
utilized;
[0009] FIG. 2 is an exploded, perspective view of a solid fuel nozzle tip
20 for use with the pulverized solid fuel-fired furnace of FIG. 1, according to an
embodiment of the invention.
[00010] FIG. 3 is a front perspective view of the nozzle tip of FIG. 2.
[00011] FIG. 4 is a rear perspective view of the nozzle tip of FIG. 2.
[00012] FIG. 5 is a front elevational view of the nozzle tip of FIG. 2.
25 [00013] FIG. 6 is a rear elevational view of the nozzle tip of FIG. 2.
DETAILED DESCRIPTION
[00014] Reference will be made below in detail to exemplary embodiments
of the invention, examples of which are illustrated in the accompanying drawings.
30 Wherever possible, the same reference characters used throughout the drawings
refer to the same or like parts. While embodiments of the invention are directed
to a nozzle tip for a solid fuel-fired furnace, embodiments of the invention may
also be used to control the velocity of fuel in any state (i.e., solid, liquid or gas).
[00015] Referring now to the drawing, and more particularly to FIG. 1
35 thereof, there is depicted therein a pulverized solid fuel-fired furnace, generally
designated by reference numeral 10. Inasmuch as the nature of the construction
and the mode of operation of pulverized solid fuel-fired furnaces known to those
skilled in the art, it is not deemed necessary, therefore, to set forth herein a
4
detailed description of the pulverized solid fuel-fired furnace 10 illustrated in FIG.
1. Rather, for purposes of obtaining an understanding of a pulverized solid fuelfired furnace 10 in the firing system of which a solid fuel nozzle tip constructed in
accordance with the invention is suited for employment, it is deemed to be
5 sufficient that there be presented herein merely a description of the nature of the
components of the pulverized solid fuel-fired furnace 10 and of the components of
the firing system with which the pulverized solid fuel-fired furnace 10 is suitably
provided and with which the solid fuel nozzle tip cooperates.
[00016] Referring further to FIG. 1, the pulverized solid fuel-fired furnace
10 10 includes a burner region 14. It is within the burner region 14 of the pulverized
solid fuel-fired furnace 10 that, in a manner known to those skilled in this art,
combustion of the pulverized solid fuel and air is initiated. The hot gases that are
produced from combustion of the pulverized solid fuel and air rise upwardly in the
pulverized solid fuel-fired furnace 10. During the upwardly movement thereof in
15 the pulverized solid fuel-fired furnace 10, the hot gases give up heat to the fluid
passing through the tubes (not shown) that in conventional fashion line all four of
the walls of the pulverized solid fuel-fired furnace 10. Then, the hot gases exit the
pulverized solid fuel-fired furnace 10 through the horizontal pass 16, which in
turn leads to the rear gas pass 18. Both the horizontal pass 16 and the rear gas
20 pass 18 commonly contain other heat exchanger surface (not shown) for
generating and superheating steam, in a manner known to those skilled in the art.
Thereafter, the steam commonly is made to flow to a turbine (not shown), which
forms one component of a turbine/generator set (not shown), such that the steam
provides the motive power to drive the turbine (not shown) and thereby also the
25 generator (not shown), which in known fashion is cooperatively associated with
the turbine, such that electricity is thus produced from the generator (not shown).
[00017] With the preceding by way of background, reference is once again
had to FIG. 1 for purposes of setting forth herein a description of the nature of the
construction and the mode of operation of the firing system with which the
30 pulverized solid fuel-fired furnace 10 is suitably provided. The subject firing
system as seen with reference to FIG. 1 includes a housing in the form of a main
windbox 20 that is provided with a plurality of air compartments (not shown)
through which air supplied from a suitable source thereof (not shown) is injected
into the burner region 14 of the pulverized solid fuel-fired furnace 10. In addition,
35 the windbox 20 is provided with a plurality of fuel compartments (not shown)
through which solid fuel is injected into the burner region 14. The solid fuel,
which is injected through the aforereferenced plurality of fuel compartments (not
shown), is supplied to this plurality of fuel compartments (not shown) by means
of a pulverized solid fuel supply means, denoted generally by the reference
5
numeral 22 in FIG 1. To this end, the pulverized solid fuel supply means 22
includes a pulverizer, denoted generally by the reference numeral 24 in FIG. 1,
and a plurality of pulverized solid fuel ducts 26. The pulverized solid fuel is
transported through the pulverized solid fuel ducts 26 from the pulverizer 24 to
5 which the pulverized solid fuel ducts 26 are connected in fluid flow relation to the
previously mentioned plurality of fuel compartments (not shown) to which the
pulverized solid fuel ducts 26 are also connected in fluid flow relation. Although
not shown in the interest of maintaining clarity of illustration in the drawing, the
pulverizer 24 is operatively connected to a fan (not shown), which in turn is
10 operatively connected in fluid flow relation with the previously mentioned
plurality of air compartments (not shown), such that air is supplied from the fan
(not shown) to not only the aforesaid plurality of air compartments (not shown)
but also to the pulverizer 24 whereby the pulverized solid fuel supplied from the
pulverizer 24 to the aforesaid plurality of fuel compartments (not shown) is
15 transported through the pulverized solid fuel ducts 26 in an air stream in a manner
known in the art.
[00018] In further regard to the nature of the firing system, two or more
discrete levels of separated overfire air are incorporated in each corner of the
pulverized solid fuel-fired furnace 10 so as to be located between the top of the
20 main windbox 20 and the furnace outlet plane 28. To this end, the firing system
with which the pulverized solid fuel-fired furnace 10 is suitably provided
embodies two or more discrete levels of separated overfire air, i.e., a low level of
separated overfire air denoted generally in FIG. 1 of the drawing by the reference
numeral 30 and a high level of separated overfire air denoted generally in FIG. 1
25 of the drawing by the reference numeral 32. The low level 30 of separated
overfire air is suitably supported through the use of any conventional form of
support means (not shown) suitable for use for such a purpose within the burner
region 14 of the pulverized solid fuel-fired furnace 10 so as to be suitably spaced
from the top of the windbox 20, and so as to be substantially aligned with the
30 longitudinal axis of the main windbox 20. Similarly, the high level 32 of
separated overfire air is suitably supported through the use of any conventional
form of support means (not shown) suitable for use for such a purpose within the
burner region 14 of the pulverized solid fuel-fired furnace 10 so as to be suitably
spaced from the low level 30 of separated overfire air, and so as to be
35 substantially aligned with the longitudinal axis of the main windbox 20. The low
level 30 of separated overfire air and the high level 32 of separated overfire air are
suitably located between the top of the main windbox 20 and the furnace outlet
plane 28 such that it will take the gases generated from the combustion of the
6
pulverized solid fuel a preestablished amount of time to travel from the top of the
main windbox 20 to the top of the high level 32 of separated overfire air.
[00019] While not illustrated in FIG. 1, pulverized solid fuel nozzles each
having a solid fuel nozzle tip are suitably supported in mounted relation within
5 each of the plurality of fuel compartments (not shown) to which reference has
been had hereinbefore. The nozzles, and nozzle tips thereof, are mounted so as to
direct pulverized solid fuel (e.g., a solid fuel such as coal and biomass, or coal)
and air into the burner region 14 of the furnace. As indicated below, according to
embodiments of the invention, the nozzle tip of one or more of the nozzles is
10 configured so as to allow for vertical and/or horizontal angular adjustment of the
nozzle tip, as well adjustment of the cross-sectional area of the nozzle tip outlet.