BRULEURS POUR CHAUDIERES

FURNACE BURNERS

Abrégé anglais

ABSTRACT

The invention provides a furnace burner that
operates with pulverized fuel. Heated combustion
air flows with a rotational movement along a burner
tube (9,119) and a slurry of pulverized fuel in
water is discharged into the air from nozzles (14,114).
The effect of the air, and the extended residence
time resulting from the rotation of the air, will
effect drying of the fuel before it reaches the
furnace opening (2,102).

Revendications

- 5 -

The embodiment of the invention in which an exclusive
property or privilege is claimed are defined as follows:-


1. In the operation of a furnace burner, introducing
combustion air into a burner tube to flow with a
rotational movement along the burner tube into the
furnace, and discharging a slurry of pulverized fuel
and water into the air to move along the tube entrained
in the air.

2. In an operation as claimed in claim 1, the air
flows rotationally along a path that converges, in
the direction of flow of the air, and the slurry is
discharged into the wider part of the path.

3. In an operation as claimed in claim 2, the con-
vergence of the path along which the air flows points
away from the furnace, and the converging path is
succeeded by a path in which the air flows back through
the convergence into the furnace chamber.

4. In an operation as claimed in claim 1, the slurry
is discharged radially outwardly in-to the air from a
plurality of nozzles disposed concentrically about the
axis of rotation o-P the air.

5. A furnace burner having a burner -tube, means by
which combustion air may be introduced into the tube
to flow along the tube with a rotational movement, and
means by which a slurry of pulverized fuel and water
may be discharged into the air to move along the tube
entrained in the air.

6. A -furnace burner as claimed in claim 5, in which
the burner tube is convergent and means is provided -for
introducing the combustion air into the wider end of
the burner -tube.




- 6 -

7. A furnace burner as claimed in claim 6, in which
the wider end of the convergent tube is nearer the
furnace than the narrower end and encircles an opening
through which the air escapes towards the furnace, and
the narrower end is closed by a wall opposite the open-
ing.

8. A furnace burner as claimed in claim 7, in which
the opening is defined by a cylinder co-axial with
the burner tube and of which the inlet end projects
towards the wall beyond the means by which combustion
air may be introduced into the burner tube.

9. A furnace chamber as claimed in claim 8 in which
a plurality of nozzles is distributed round, and mounted
on, the cylinder, the nozzles discharge radially out-
wardly and serve as the means by which the slurry may be
discharged.

10. A furnace burner as claimed in claim 5 in which
the means for discharging the slurry includes a plurality
of nozzles disposed concentrically within the burner tube
and discharging radially outwardly.

Description

37


~Improvements in or rel~ing to Furnacs ~urners"

DESCRIPTION

This invention relates to burnsrs by which fuel may
bs burnt in a furnace and is conc~rned to facilitate the
USB of pulverized fuel supplied from a source in the
form af a slurry comprising pulverised fuel mixed with
water.

The invention may bs sesn in, in the operation of a
furnace burner, inkroduoing warm combustion air into
a burnsr tube to flow with a rotational movement along
the burner tube into the furnace, and discharging a
slurry o~f pulverised fus~ and watsr into ths air to
movs along the tube entrai~s~ in ths air.

The ;nvsntion also providss a furnace burner having
a burner tube, ~eans by which combustion air may b8
introduced into the tube to flow along the tube with
a rotational movemsnt, and m~ans by whioh a slurry
of pulverized fuel and water may bs discharged into
the air to move along ths tube entrained in the air.

By way o~ example, emhodiments of the invention
; will now bs ds~cribed with rsfzrence to the accompanying
drawings in which:
Figure 1 shows in vertical axial cross s~ction
: a burnsr, arrangsd for the combustion of pulveri~sd
: fuel, mountzd at the wall o~ a furnace~ and
Figure 2 shows in v~rtical axial cross section a
modiflcation o~ what i~ shown in Figurs 1.




A
,.~

3'~



In Figure 1, a furnace wall is denoted by 1O The
wall has a burner opening 2 leading from windbnx 3
that is supplied through an opening 4 in the bottom
with heated air..

A burner mouth 5 is formed around the burn~r
opening 2 and a ligh~-up and stabilization oil tube B,
having impellors ~a at its outle~ end, disGharga~
concentrically through the mouth 5O Concentrically
around the tub2 8 is the burner tube 9O This com-
1û prises an inlet part 9a, that is convergent towards
the ~urnace. The wider znd is separated by a gap
from the end wall 3a of a windbox 3, and the narrower
znd opens to an outlet part 9b of constant cross-
section~ Surrounding the part 9b is a secondary
swirl register 10. ThQ gap between the wider end of
the tube 9 and the end wall 3a of the windbox 3 is
occupied by inlet vanes 11, cont.rolled by a sleeve
d~mper 12, that permits air to ~low from the windbox 3
into the tube 9 and impart rotational movement to the
air flowing into thQ tube 9.

An array of atomizing nozzles 14 is distributed
araund the oil tube B and arranged to dischargs radially
outwardly into air 3dmittsd between the vanes 11. The
nozzles 14 ars supplied through pipe 1S from a source
lnot shown) of a slurry of pulverizsd fual mixed with
water.

3~

3 -

In operation of the burner that has been
described, with air admitted between the vanes 11
and slurry discharged From the nozzles 14, ths
dischargad slurry i~ entrained in the incoming air
5 and is therefore taken along a spiralli~g path that
converges towards the furnace. The residence time
in khe burner tube is therefore extended 50 that
whilsk the slurry may be in the optimum condition
~or supply to the nozzles 14, but too moist for the
10 most efficient combustion of the fuel9 its axtended
psriod in the heated air will effect drying. The
fuel will khsrefore be more readily combustible and
flame stability will be enhanced~ The residence time
in the burner tube is promoted by its conical form.
15 The dryin~ action of ths heat will be re-in~orced by
a sort of scrubbing e~ect resulting from the dis-
charge of the atomized slurry at one velocity into
the rotationally moving pre-heated air at anothar.

The parts of the burner illustrated in Figure
20 2 that are similar to parts of the burner illustrated
in Figure 1 are denoted by the 6ame reference numbers,
to which 100 has been added. The essential diPference
lies in the form cf the ~urnsr tube, of which the
outlet part 109~ leads through the swirl register 110.
25 The inlet part~ 119, however, whilst being o~ conical
form, tapers towards the rear wall 103a of the wind-
box, Tha inlet vanes 111 through which air passes into
the part 119 lie between the wider end of the part 119
and the secondary sw;rl register 110~ No~zles 114
30 through which akomi~ed slurry may be discharged into
the heated air swirling in the part 119 are disposed
around the part 109b.

3~7


In use of the apparatus shown in Figure 2,
the swirling air first flows away from the furnacs
along a pa~h that, by change af direction, lsads then
to the furnace~ Thus, the swirling occurs in the air
5 flowing to the furnace but in a direction away from
the ~urnace, At the rear wall 103a, the direction
of flow reverses and air, and the entrained slurry,
flow thence into the furnace. By embodying this
changY o~ direction, the residsnce time of the slurry
in hsated air is fur~her increased~

It will be noted that in each of the embodi-
ments described, th~ entire burner can be introduced
into the windbox through an openin~ that is oP a
diameter suf~icien~ly large to accept the swirl
register ~0 ~or 110). Whilst the drying air
admitted by ths vanes 11 ~or 111) and the secondary
air admitted through the swirl register 10 ~or 110)
como from a common windbox~ it is 2nvisagsd that
the drying air could be supplied fro~ a separate
source. Burners such as have been described may
be produced by the ready modification of burners
that have previously been installed for the combustion
o~ heavy ~uel oilO