Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to incinerators and associated
apparatus, more specifically to incinerators for burning solid
wastes or garbage, discarded from households.
Municipal and household garbage or trash is normally
delivered to a central location, and the combustible portion
is disposed of by combustion in an incinerator. The type of
incinerator which is used should be simple to maintain and ~; ;
operate, consume relatively small amounts of fuel, and produce
ash or other residual waste products which are clean and readily
disposable. In addition~ however, it is important that the
incinerator and associated apparatus operate in a clean manner,
without producing from the aarbage being incinerated and
releasing into the atmosphere excessive amounts oE air borne
solid pollutants.
For simple and efficient operation of a solid gar-
bage incinerator, it is desirable that the burning of garbage
therein take place continuously over a substantial period of
time of several hours, with intermittent or continuous
addition o~ further ~uantities of solid garbage to the already
burning garbage in the incinerator. Loading the incinerator
in a simple manner, while the garbage therein is burning,
without allowing escape of excessive amounts of air borne
solid material, presents problems.
It is an object of the present invention to provide
a novel incinerator ~seful for burning solid garbage, which
reduces the aforementioned problems.
The invention provides a trash incinerator which can
be loaded at will with trash for incineration, through a
convenient top opening directly above the fire, but which is
arrangea substantially to prevent exhaust gases and solid air-
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borne combustion products from issuing through the top opening.
This is ~chieved by blowing a stream of air from side to side
across the comhustion chamber below the top opening but above the
fire. This creates an air curtain which suhstantially prevents
5 issue of exhaust gases and solid air-borne particles upwardly ;~
through it and hence through the top opening. The air introduced
into the chamber in this way serves as a source of over-fire
combustion air. The delivery of combustion air in this manner
and suitably arrangement of the exhaust outlet from the combustion ;
chamber into an after-burner chamber helps to establish
circulating air patterns which lead to efficient combustion and
reduced requirements for combustion air.
Thus, according to the present invention, there is
provided an incinerator for incineration therein of combustible
products, said incinerator comprising a combustion chamber and an
after-burner chamber;
the combustion chamber having a bottom surface for
receiving combustible material, a loading aperture located above
the bottom surface, through which combustible material may be
dropped onto the bottom surface for incineration, and air inlet
means located at a vertical level below the aperture and adapted
to blow comb~stion air at substantial velocity across the upper
interior of the combustion chamber below the loading aperture and
above the level of combustible material in a chamber, to create an
air curtain and control air flows across said aperture;
after-burner chamber communicating with the combustion
chamber at a level below that of the lowest extent of the air
curtain, and communicating with a gas exhaust means;
means for supplying air to the after-burner chamber to
mix with the hot exhaust gases received therein from the
combustion chamber~
The air inlet means preferably comprise air inlet nozzles,
jets or horizontal slotsl arranged along the top part of one side
wall of the combustion chamber, directed in a slight downward direc-
tion across the width of the combustion chamber, so as to provide an
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air curtain across the upper loading aperture and to establish ;~
satisfactory air circulation patterns within the chamber. Most
preferably, the means for blowing in air comprises a continuous ~ :~
slot air jet extending substantially the full width of a side
wall of the combustion chamber.
~ n a preferred embodiment, the combustion chamberis also provided, near its bottom wall, with under-fire air
inlet means, through which additional amounts of air, optionally -
in admixture with a fuel oil, can he admitted to assist in
obtaining complete combustion of garbage in the incinerator.
The velocity of the air blown across the upper
interior of the chamber should be substantial, and high enough
to create an effective air curtain and air circulation
within the chamber. To some extent, the velocity of air at the
air inlet means necessary to achieve these desirable results
depends upon the size and geometry of the combustion chamber, ;
and the amount of garbage and combustion temperature in the
combustion chamber. The velocity of thi~s air is preferably
from about 4,000 to about 16,000 feet per minute, most preferably
from about 8,000 to about 16,000 feet per minute, depending to
some extent upon the width of the chamber across which the air
is blown. In general , the smaller this width, the lower the
air velocity can be to form an effective air curtain.
As noted, the incinerator of the invention
includes an after-burner chamber communicating with the
combustion chamber at a location below the air curtain. Combustion
gases from the combustion chamber exhaust into the after-burner
chamber. Preferably, the combustion chamber is generally
rectangular as viewed in plan, with the air inlet slot extending
continuously along one side wall and the communication between
the combustion chamber and the after burner chamber is at one
end of the combustion chamber.
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The after burner chamber is supplied with means for
supplying air thereto, to mix with the hot exhaust gases from the
combustion chamber and to ensure complete combustion thereof.
Some of the air needed for complete combustion is added to the
5 exhaust gases in the after-burner. This reduces the amount of ~-
solid material carried over into the subsequent exhaust stages of
the incinerator system. It also assists in providing control of
the amount of air added. The total amount of air ~hich is
added, both to the combustion chamber and to the after-burner
chamber is such as to maintain the necessary high temperatures for
complete combustion. The provision of some of the necessary air
to the after-burner chamber allows the amount of air necessary to
be adjusted by monitoring the temperature in the after-burner
chamber. In the most preferred embodiment according to the
inventionl the after-burner chamber is designed so that the hot
exhaust gases have a cyclonic flow path therein. By these means,
better mixing of the exhaust gases with incoming air, to achieve
complete combustion, is achieved. Also, suspended solid matter
tends to be removed from the gases by such a flow pattern, by
certrifugal action, to drop into the after-burner chamber.
The incinerator of the present invention is suitably
associated with other components of standard type, for suitably `
processing and treating the exhaust gases before they are
discharged into the environment. A fluid propelling means such
as a fan is preferably provided, downstream of the after-burner
chamber, to assist in drawing the exhaust gases through the
incinerator and establish the air and gas flow patterns in the
combustion chamber. The incinerator is suitably also associated
with the heat exchanger or cooling chamber in which hot gases
issuing from the after-burner chamber may be cooled, a cleaning
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means such as a cyclone air cleaner which will extract suspended
particles from the exhaust gas streams, and a discharge chimney
stack, all of generally standard form. Such items of equipment
may be associated with a single combustion and after burner :
chamber according to the invention, or alternatively and -~
preferably, two or more combustion and after burner chambers
according to the invention may be associated with a single
common heat exchanger or cooling chamber~ gas cleaner~ draw fan
and chimney stack.
The amount of air or oxygen theoretically required~
to cause complete combustion of a given amount of garhage can be
; calculated, and such figures are readily available to those
working in this field. It is however normal to supply two and
three times the theoretical, stoichiometric amount of air in
conventional garbage incineration, to ensure substantially
complete incineration of the garbage. However, in the incinerator
according to the present invention, such large excesses of
combustion air have been found to be unnecessary. The
combustion air is supplied, in the preferred embodiment, both to
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the c~b~it~n chamber as over-fire and under-fire alr and to the
after burner chamber. Complete incineration of the garbage can
be achieved, in many instances, with close to the stoichiometric,
or by using only small excess, amounts of air in the incinerator
of the present invention, largely due to the air flow patterns
and circulations established in the combustion chamber. The
amounts are substantially lower than conventionally used in
incinerators for this purpose. In addition, the provision of the -
air supply in a manner to create an air curtain across the top - ;
inlet, as well as these air flow patterns, means that a top
loading aperture, direstly above the fire, can be used, without
substantial risk of escape of air-borne particles into the
environment thèrefrom. For ease and simplicity of loading, ~
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'and rapid incineration, the provision of a loading aperturedirectly above the fire, so that garbage can be simply tipped or
thrown in as incineration proceeds, is much to be preferred.
The incinerator according to the present invention allows this
feature to be used, without top cover, gates, grilles or the
like, whilst at the same time preserving simplicity of
structural features and substantial absence of moving parts.
Further, the incinerator according to the
preferred form of the present invention does not involve any
mechanical agitation of the garbage during combustion. Grates
or the like, which case the solid burning garbage to fall during
incineration, are not necessary. The air and gases flow around
and through the burning garbage, but no substantial disturbance `~
of it is caused. Consequently the amount of ash and the like
which is carried over in the exhaust gas stream, into and
through the after burner chamber, is low. This means that the
gas purifying equipment employed downstream of the after burner
chamber can be of a lower cost, simpler type, e.g. of the
cyclone type instead of an electrostatic precipitator, to
reduce emissions to acceptable levels.
A specific embodiment of an incinerator according
to the invention, with associated parts, is illustrated in the
accompanying drawings, in which:
FIG.1 is a top plan view, partly cut away and
somewhat diagrammatic, of an incinerator assembly according to
the present invention; ~ `
YIG.2 is a cross sectional side elevatio~ of the
combustion and after burner chambers of the incinerator assembly
of Fig. 1, taken along the line 2-2 of Fig. l;
FIG.3 is a cross sectional view of the combus~ion
chamker along the line 3-3 of Fig. 2;
FIG. 4 is a diagrammatic side view, partly in
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section of the incinerator assembly of Fig. l;
FIG. S is a vertical cross sectional view of the
quench tower of the incinerator assembly of Fig.s 1-4, along the
line 5-S of Fig~ 4.
In the drawings, lile reference numerals indicate
like parts.
With reference to Fig. 1, the incinerator assembly
according to the invention includes two combustion chambers 10,
11, each communicating with an associated after-burner chamber
12, 13. The combustion chambers 10 and 11 are rectangular as -~
viewed in plan and the respective upper walls 14, 15 thereof
are provided with top rectangular apertures 16, 17 respectively,
through which garbage for combustion can be dropped into the
combustion chambers. The after-burner chambers 12, 13 are
provided with respective fuel oil burners 18, 19 in side walls
thereof, ~hich can be operated to assist in complete combustion
of any combustible material carried over from the combustion
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chambers 10, 11.
The after-burner chambers 12, 13 are both in
communication with the lower end of a single generally vertically
disposed quenching tower 20. Exhaust gases from the combustion
chambers 10, 11 thus pass through the after-burner chambers 12,
13 and then upwardly through ~uench tower 20. A removable top
cover plate 21 is provided at the top of the quench tower 20. ;~
The quench tower is also provided with a pair of air inlets 22,
23 through which cooling air can be drawn in from outside as
gases flow upwardly through the tower 20. The upper part of the
tower 20 communicates by suitable ducting 24, 25 to other `
associated parts of standard form, omitted from Fig. 1. A gas
cleaner 26 of the cyclone type is provided below ducting 24 and
communicating therewith/ to remove suspended air borne particles
from the gases flowing through ducting 24.
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~ ith reference to Fig. 2 and 3, the combustion
chamber 10 and after-burner chamber 12 are in communication at
27 at a level below that of the air curtain. The combustion
chamber 10 i5 generally rectangular as viewed in plan, and the
communication 27 with the after-burner chamber is at one end 28
of the combustion chamber.
As shown in Fig. 3 the combustion chamber 10 is
provided with an over-fire air inlet means 29, in the form of a
horizontally disposed slot jet extending along the length of one
side wall of the chamber 10. The slot jet 29 is formed as the ~ .
outlet from a triangular cross-section air chamber 30 extending the
length of the chamber 10, and defined between a downwardly inclined
upper plate 31 and a horizontal projection 32 extending from the
side wall inwardly of the chamber 10. A correspondlng downwardly
inclined upper plate 33 and horizontal projection 34 are pro~ided
on the opposed side wall of the chamber 10. The do~Jnwardly inclined
plates 31, 33 comprise theupper wall 14 of the chamber 10 and `~
provide a loading chute for garbage entering the chamber 10 for
incineration. The lower, inner edges of the plates 31, 33 define
the aperture 16 in the upper wall of the chamber 10. Air
supplied through slot jet 29 thus provides over-fire combustion
air, and forms an air curtain below aperture 16.
The chamber 10 is lined àlong its side walls
with linings of a refractory material 35, 36. The upper ends of
linings 35, 36 are inwardly inclined formations 37, 38
respectively. These formations assist in the establishment
of circular flow patterns around the chamber 10, of air from
the jets 29, this circulation being generally clockwise, as
viewed in Fig. 3, through the burning trash 39 therein. As
shown in Fig. 3, the jet 29 is arranged to blow primary
combustion air into the chamber 10 across the width of the
chamber 10 below the level of upper aperture 16 and above the
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level of the burning trash 39, at a slight downward angle. ;~
The combustion chamber 10 is also provided ~ -
with a pair of sets of air/oil inlets 40, 41, one set extending
along the bottom of each side wall of the chamber 10. The
inlets 40, 41 can be used to feed into the chamber 10 under-fire
combustion air during the burning of garbage 39 in the chamber
10. Supplying air through these inlets can assist in establishing
the desirable flow patterns in the chamber 10, and serve to burn off
c~-~on deposits forming in the lower portion of the chamber 10.
These same inlets 40, 41 can also be used if desired, to supply
fuel into the chamber 10, to assist in the incinerator operation ;~
e.g. when starting up the incinerator or when a difficultly
combustible garbage item is present in the chamber 10. The sets
of inlets 40, 41 extend the length of the side walls of the
chamber 10, being defined between the bottom of the side wall
refractory linings 35, 36 and a refractory bottom wall 42 of the
chamber 10. ~ - ~
The end of chamber 10 remote from its communication ~ ~ -
with after-burner chamber 12 is provided with doors 43 openable ~
20 to remove ash periodically as desired, from the bottom of ~ `
combustion chamber 10. `~
The after-burner chamber 12, as shown in Fig. 2,
has a series of air inlet jets 44 near the bottom thereof,
through which further combustion air is supplied to mix with
the hot gases issuing from chamber 10 into after-burner chamber ;
12, and to assist, in conj`unction with burner 18, in completing
combustion of any combustible products carried over into after-
burner chamber 12. The jets 4d are provided along the length of the ;
side wall o~ the after-burner chamber. The front wall of after-
burner chamber 12 is comprised of a baffle 45 of refractory
material, extending upwardly from the bottom wall of chamber 12,
around which the hot exhaust gases pass in entering after-burner
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~chamber 12. The top wall 45a of after-burner chamber 12 has
rounded corners and is generally in the shape of an arch. ThiS
promotes cyclonic flow of the exhaust gases in chamber 12, to
assist in mixing with air from inlet 44 and to assist in
centrifuging out particulate matter from the exhaust gas stream. .
The hot exhaust gases issue from the after-burner
ch~mbers 12, 13 via respective apertures 46, 47 into the quench
tower 20, in which the gases move upwardly. The quench tower
20 is provided, at each side, with air inlets 48, 49 (Fig.5).
Air is drawn in through inlets 48, 49 by the combustion gases
moving upwardly through tower 20, to mingle with these gases
and assist in their cooling and treatment. The cooling tower
20 is also provided with water jets 50, 51 (Fig.4), through
which water is introduced to quench the hot gases flowing up
the tower 20. The amount of water supplied is sufficient to
cause quenching by evaporation of the water, but insufficient
to cause substantial condensation of the water in the tower
20. A clean-out door 52 is provided at the foot of tower 20. `;
The hot gases exit from near the top of the
quench tower 20 via a duct 24. A cyclone type gas cleaner 26
of Xnown type, is connected to the underside of duct 24, to
assist in removing suspended solids from gases passing through
duct 24. From duct 24, the gases are drawn downwardly through
downwardly inclined duct 25 by induction draw fan 53, and vent
via duct 5a to chimney stack 55, from the upper end of whlch
the gases are discharged.
As shown in Fig. 4, the combustion chamber 10
is provided, above its upper aperture 16, with a screen arrange~
ment 56, to assist in loading the trash to be burned into the
chamber, and to prevent dispersal of the trash by wind, during
loading of the combustion chamber.
The incinerator of the invention is simple in
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construction and operation, being substantially free from
moving parts and structural complexities in the combustion zone.
It provides efficient incineration of normal items of trash of
the type collected by municipal authorities, with simple and
economical operation and loading.
It will be appreciated that changes in structural
items and operational details can be made in the incinerator
according to the-invention, without departure from the scope
of the present invention, which is limited only by the scope
10 of the appended claims. ~`
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