U.S. patent number 3,656,440 [Application Number 05/083,711] was granted by the patent office on 1972-04-18 for incinerator having means for treating combustion gases.
This patent grant is currently assigned to Morse Boulger, Inc.. Invention is credited to Jerry Grey.
United States Patent |
3,656,440 |
Grey |
April 18, 1972 |
INCINERATOR HAVING MEANS FOR TREATING COMBUSTION GASES
Abstract
An incinerator generally including a combustion chamber, a flue,
means for conducting combustion gases emanating from the combustion
chamber to the flue, the conducting means including passage means
for imparting a curved motion to the combustion gases, means
disposed in the passage means for producing a plurality of
electrostatic fields including a plurality of sets of spaced
electrodes, each set of electrodes producing an electrostatic field
through which a portion of the gases traverse, and means disposed
either upstream relative to the means for producing a plurality of
electrostatic fields, or in conjunction therewith, for ionizing the
combustion gases, whereby contaminants including solids and gaseous
molecules entrained in the combustion gases will be ionized by the
ionizing means and subjected to cooperating centrifugal,
electrostatic and gravitational forces as the gases traverse
through the passage means to remove the contaminants from the
combustion gases.
Inventors: |
Grey; Jerry (New York, NY) |
Assignee: |
Morse Boulger, Inc. (Corona,
NY)
|
Family
ID: |
22180186 |
Appl.
No.: |
05/083,711 |
Filed: |
October 26, 1970 |
Current U.S.
Class: |
110/215; 110/216;
110/119; 96/48; 96/57; 96/65; 96/53 |
Current CPC
Class: |
F23J
15/02 (20130101); F23J 15/022 (20130101); B03C
3/15 (20130101) |
Current International
Class: |
B03C
3/15 (20060101); F23J 15/02 (20060101); B03C
3/04 (20060101); F23g 005/00 () |
Field of
Search: |
;110/7,8,18,119
;55/5,13,118,120,126,127,130,138,145 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sprague; Kenneth W.
Claims
I claim:
1. An incinerator comprising a combustion chamber, a flue, means
for conducting combustion gases emanating said combustion chamber
to said flue, said conducting means including passage means for
imparting a curved motion to said combustion gases, means disposed
in said passage means for producing a plurality of electrostatic
fields including a plurality of sets of spaced electrodes, each set
of electrodes producing an electrostatic field through which a
portion of said gases traverse, and means disposed upstream
relative to said means for producing a plurality of electrostatic
fields, for ionizing said combustion gases whereby solid and
gaseous contaminants entrained in said combustion gases will be
ionized by said ionizing means and subjected to cooperating
centrifugal, electrostatic and gravitational forces as said gases
traverse said passage means to remove said contaminants from said
combustion gases.
2. An incinerator according to claim 1 including a secondary
combustion chamber disposed between said first mentioned combustion
chamber and said gas conducting means.
3. An incinerator according to claim 1 including means disposed
between said combustion chamber and said gas conducting means for
removing contaminants larger than a predetermined size.
4. An incinerator according to claim 3 wherein said means for
removing contaminants larger than a predetermined size comprises a
gas washer.
5. An incinerator according to claim 1 including a settling chamber
disposed between said gas conducting means and said flue, having
means upon which contaminants diverted from the main stream of
combustion gases traversing through said gas conducting means, may
impinge thus losing their kinetic energy.
6. An incinerator according to claim 1 including means for removing
contaminants precipitated from said combustion gases and deposited
on said electrodes.
7. An incinerator according to claim 1 including a secondary
combustion chamber and means for removing contaminants larger than
a predetermined size from said combustion gases emanating from said
combustion chambers disposed between said first mentioned
combustion chamber and said gas conducting means, and a settling
chamber disposed between said gas conducting means and said flue,
having means upon which contaminants diverted from the main stream
of said combustion gases may impinge.
8. An incinerator according to claim 7 including means for removing
contaminants deposited on said electrodes.
9. An incinerator according to claim 1 wherein the electrodes of
each of said sets of electrodes comprise elongated plates disposed
sufficiently adjacent along the lengths thereof to provide an
electrostatic field having sufficient strength to precipitate
ionized contaminants traversing therethrough.
10. An incinerator according to claim 9 wherein said electrodes
consist of spaced rectilinear plates.
11. An incinerator according to claim 9 wherein said electrodes
consist of spaced, curved plates.
12. An incinerator according to claim 9 wherein said electrodes
consist of spaced, curved plates having substantially tangential
trailing end portions.
13. An incinerator comprising a combustion chamber, a flue, means
for conducting combustion gases emanating from said combustion
chamber to said flue, said conducting means including passage means
for imparting a curved motion to said combustion gases, means
disposed in said passage means for producing a plurality of
electrostatic fields including a plurality of sets of spaced
electrodes, each set of electrodes producing an electrostatic field
of sufficient strength to produce a corona discharge for ionizing
said combustion gases traversing therethrough whereby solid and
gaseous contaminants entrained in said combustion gases emanating
from said combustion chamber will be subjected to cooperating
centrifugal, electrostatic and gravitational forces as said gases
traverse said gas conducting means to remove said contaminants from
said combustion gases.
14. An incinerator according to claim 13 including a secondary
combustion chamber disposed between said first mentioned combustion
chamber and said gas conducting means.
15. An incinerator according to claim 13 including means disposed
between said combustion chamber and said gas conducting means for
removing contaminants larger than a predetermined size.
16. An incinerator according to claim 15 wherein said means for
removing contaminants larger than a predetermined size comprises a
gas washer.
17. An incinerator according to claim 1 including a settling
chamber disposed between said gas conducting means and said flue,
having means upon which contaminants diverted from the main stream
of combustion gases traversing through said gas conducting means
may impinge.
18. An incinerator according to claim 13 including means for
removing contaminants deposited on said electrodes.
19. An incinerator according to claim 13 including a secondary
combustion chamber and means for removing contaminants larger than
a predetermined size from said combustion gases emanating from said
combustion chambers, disposed between said first mentioned
combustion chamber and said gas conducting means, and a settling
chamber disposed between said gas conducting means and said flue,
having means upon which contaminants diverted from the main stream
of said combustion gases may impinge.
20. An incinerator according to claim 19 including means for
removing contaminants deposited on said electrodes.
21. An incinerator according to claim 13 wherein the electrodes of
each of said sets of electrodes comprise elongated plates, one of
which is provided with a projection extending toward the other of
said plates, for emitting a corona discharge between said
plates.
22. An incinerator according to claim 21 wherein said electrodes
consist of spaced, rectilinear plates.
23. An incinerator according to claim 21 wherein said electrodes
consist of spaced, curved plates.
24. An incinerator according to claim 21 wherein said electrodes
consist of spaced, curved plates having substantially tangential
trailing end portions.
25. An incinerator comprising a combustion chamber, a settling
chamber, a flue, said settling chamber having an upwardly extending
inlet passageway communicating with said combustion chamber and an
upwardly extending outlet passageway communicating with said flue
wherein said inlet passageway, said settling chamber, and said
outlet passageway provide a continuous passageway for combustion
gases emanating from said combustion chamber and exhausted through
said flue, said inlet and outlet passageways being spaced
sufficiently apart whereby combustion gases passing through said
settling chamber follow a curved path about a center of curvature
disposed between said passageways, said outlet passageway having an
inlet disposed sufficiently adjacent to said center of curvature
whereby contaminants entrained in said combustion gases passing
through said settling chamber are caused to be diverted from the
main stream of said gases by centrifugal forces, means disposed in
said inlet passageway for ionizing combustion gases introduced into
said settling chamber, and means disposed in said settling chamber
between said inlet and outlet passageways for producing a plurality
of electrostatic fields including a plurality of sets of spaced
electrodes, each set of electrodes producing an electrostatic field
through which a portion of said gases traverse whereby solid and
gaseous contaminants entrained in said combustion gases will be
ionized by said ionizing means and subjected to cooperating
centrifugal, electrostatic and gravitational forces as said gases
traverse said settling chamber to remove said contaminants from
said combustion gases.
26. An incinerator comprising a combustion chamber, a settling
chamber, a flue, said settling chamber having an upwardly extending
inlet passageway communicating with said combustion chamber and an
upwardly extending outlet passageway communicating with said flue
wherein said inlet passageway, said settling chamber, and said
outlet passageway provide a continous passageway for combustion
gases emanating from said combustion chamber and exhausted through
said flue, said inlet and outlet passageways being spaced
sufficiently apart whereby combustion gases passing through said
settling chamber follow a curved path about a center of curvature
disposed between said passageways, said outlet passageway having an
inlet disposed sufficiently adjacent to said center of curvature
whereby solid and gaseous contaminants entrained in said combustion
gases passing through said settling chamber are caused to be
diverted from the main stream of said gases by centrifugal forces,
and means disposed in said settling chamber between said inlet and
outlet passageways for producing a plurality of electrostatic
fields including a plurality of sets of spaced electrodes, each set
of electrodes producing an electrostatic field of sufficient
strength to produce a corona discharge for ionizing said combustion
gases traversing therethrough whereby contaminants entrained in
said combustion gases will be subjected to cooperating centrifugal,
electrostatic and gravitational forces as said gases traverse said
settling chamber to remove said contaminants from said combustion
gases.
Description
This invention relates to a novel incinerator and more particularly
to an incinerator capable of producing a low particulate content
and reduced concentrations of gaseous contaminants in the effluent
emitted therefrom. This invention further contemplates a novel
apparatus for removing solid and gaseous contaminants from a stream
of gases, suitable for use in incinerators and other effluent
emitting devices wherein it is desired to remove solid and gaseous
contaminants from the effluent.
In the past, the most practical and economical method of solid
waste disposal has been incineration. In view of this, many
municipal, industrial, commercial and residential types of
incinerators have been designed, erected and operated over a period
of decades. With the increased use of such incinerators and other
sources of effluent emissions into the atmosphere, such as
automotive exhaust emissions and industrial and power plant
emissions, the pollution of the atmosphere has approached critical
levels potentially hazardous to human and animal life.
As a result of the increased pollution of the atmosphere, federal,
state, county and municipal governments have enacted legislation
establishing more stringent code requirements with respect to
effluent emissions of municipal, industrial and residential
incinerators. Many government codes require the particulate loading
of effluent emission not to exceed 0.10 to 0.20 grains per standard
cubic foot. It has been found, however, that most existing
incinerators and other installations emitting effluent into the
atmosphere, are incapable of complying with such code requirements.
Furthermore, it has been found that most new incinerator designs
which have been proposed, perhaps may be capable of complying with
such code requirements but are economically unfeasible to erect and
operate.
Accordingly, it is the principal object of the present invention to
provide a novel apparatus for removing particulate entrained in a
stream of gas.
Another object of the present invention is to provide a novel
apparatus suitable for use with a device emitting effluent into the
atmosphere to remove particulate entrained in such effluent.
A further object of the present invention is to provide a novel
apparatus suitable for use with a device emitting particulate laden
effluent into the atmosphere, for removing said particulate so that
the particulate loading of the effluent will approach the
particulate loading of the ambient atmosphere.
A still further object of the present invention is to provide a
novel apparatus for removing particulate entrained in a stream of
gas which is relatively simple in construction and comparatively
inexpensive to operate.
Another object of the present invention is to provide a novel
incinerator.
A further object of the present invention is to provide a novel
incinerator operable to produce an effluent emission having a low
particulate content.
A still further object of the present invention is to provide a
novel incinerator capable of producing an effluent emission having
a particulate loading approaching the particulate loading of the
ambient atmosphere.
Another object of the present invention is to provide a novel
incinerator capable of producing an effluent emission of low
particulate loading, thus minimizing the particulate pollution of
the atmosphere in the operation of the incinerator.
Another object of the present invention is to provide a novel
incinerator capable of meeting governmental code requirements
pertaining to pollution of the atmosphere.
A further object of the present invention is to provide a novel
incinerator capable of producing an effluent emission having a
particulate loading approaching the particulate loading of the
ambient atmosphere, which is simple in construction and
comparatively inexpensive to erect, operate and service.
Another object of the invention is to provide a novel apparatus and
method for reducing the concentration of gaseous contaminant of a
stream of gas.
A further object of the invention is to provide a novel apparatus
and method for reducing both the solid and gaseous contaminant of a
stream of gas, and particularly a stream of combustion gases.
Other objects and advantages of the present invention will become
more apparent to those persons having ordinary skill in the art to
which the invention pertains, from the following description taken
in conjunction with the accompanying drawings wherein:
FIG. 1 is a vertical cross-sectional view of an embodiment of the
invention;
FIG. 2 is an enlarged cross-sectional view taken along line 2--2 in
FIG. 1;
FIG. 3 is a vertical cross-sectional view of another embodiment of
the invention;
FIG. 4 is an enlarged cross-sectional view taken along line 4--4 in
FIG. 3;
FIG. 5 is a vertical cross-sectional view of a third embodiment of
the invention; and
FIG. 6 is a cross-sectional view taken along line 6--6 in FIG.
5.
Briefly described, according to one embodiment, the present
invention relates to an incinerator generally including a
combustion chamber, a flue, means for conducting combustion gases
emanating from the combustion chamber to the flue, the conducting
means including passage means for imparting a curved motion to the
combustion gases, means disposed in the passage means for producing
a plurality of electrostatic fields including a plurality of sets
of spaced electrodes, each set of electrodes producing an
electrostatic field through which a portion of the combustion gases
traverse, and means disposed upstream relative to the means for
producing the plurality of electrostatic fields, for ionizing the
combustion gases whereby particulate entrained in the combustion
gases will be ionized by the ionizing means and subjected to
cooperating centrifugal, electrostatic and gravitational forces as
the combustion gases traverse through the passage means to remove
the particulate from the combustion gases. Preferably, the
incinerator further includes a secondary combustion chamber and
means for removing particulate larger than a predetermined size, in
the order of 3 to 5 microns, from the combustion gases emanating
from the combustion chambers, disposed between the primary chamber
and the gas conducting means, and a settling chamber disposed
between the gas conducting means and the flue, having means upon
which particulate diverted from the main stream of gases and not
previously collected, may impinge.
In the embodiment as described, the ionization and electrostatic
precipitation of the particulate entrained in the stream of
combustion gases occur in separate stages. The combustion gases are
first ionized and then subsequently caused to pass through a
plurality of electrostatic fields which function to precipitate the
ionized particles. In another embodiment of the invention, the
electrostatic precipitation of the particulate in the gas stream is
accomplished in a single stage wherein the plurality of
electrostatic fields are of sufficient strength to produce corona
discharges which function to ionize particulate entrained in the
gas stream, which are precipitated by the same electrostatic fields
producing the corona discharges.
In both embodiments as broadly described, it is contemplated that a
combination of centrifugal, electrostatic and gravitational forces
will be applied to particulate entrained in the stream of
combustion gases emanating from the combustion chamber and flowing
to the flue of the incinerator, to remove such particulate from the
main stream of the gases. Simultaneously, electrostatic forces are
applied to ionize molecules of gaseous contaminants, to further
remove such contaminants from the gas stream. To increase the
overall efficiency of the incinerator, it further is contemplated
to utilize a secondary combustion chamber disposed upstream of the
combined separator, to prolong combustion, thus reducing the
particulate content of the combustion gases, and also to utilize an
upstream scrubber chamber which is effective in removing
particulate of 5 microns or larger in size, and cooling the gases,
thus reducing the power requirements and increasing the
effectiveness of the electrostatic precipitators.
Referring to FIGS. 1 and 2 of the drawings, there is illustrated
the first embodiment of the invention utilizing a two stage
electrostatic precipitator. The embodiment includes a housing
structure 10 having an upper wall 11, a lower wall 12, a front end
wall 13, a rear end wall 14, and a pair of side walls 15,15. The
various walls of the housing structure are either constructed of or
lined on the interior sides thereof with a fire resistent material
such as firebrick and the like. Disposed within the housing
structure is a partition wall 16 consisting of firebrick, which is
spaced from the front end wall 13, and a partition wall 17 spaced
from the rear end wall 14, providing a combustion chamber 18, a gas
washer or scrubber chamber 19 and a settling chamber 20. The upper
end of the partition wall 16 terminates below the upper wall 11 to
provide a horizontal passageway 21. The front end wall 13 is
provided with a charging opening 22 communicating with the
combustion chamber 18 through which refuse may be charged into the
combustion chamber onto a grate 23 mounted in the lower end of the
combustion chamber and spaced from the lower wall 12. Conventional
openings are provided in at least one of the side walls below the
grate 23 for removing ash deposited in the bottom of the combustion
chamber below the grate 23. Although a simple combustion chamber
having a grate for supporting refuse and an opening for charging
refuse into the combustion chamber are shown in FIG. 1, it is to be
understood that any suitable type of combustion chamber utilizing
any type of charging system and grate assembly or stoker may be
used within the scope of the invention.
Depending from the upper wall 11 and extending into the scrubber
chamber 19, is a curtain wall 24. The lower end of the curtain wall
projects below the upper level of the partition walls 16 and 17,
and is spaced from the lower wall 12. In addition, the curtain wall
24 is spaced from the partition walls 16 and 17, to provide
vertical passageways 25 and 26 on opposite sides of the curtain
wall. The vertical passageway 25 intercommunicates the horizontal
passageway 21 and the scrubber chamber 19, and the vertical
passageway 26 intercommunicates the settling chamber 20 with a
horizontal passageway 27 formed by the termination of the upper end
of the partition wall 17 below the upper wall 11.
Supported on the side walls 15,15 and disposed in the vertical
passageway 26 is a horizontal baffle 28 having the front end 29
spaced from the curtain wall 24 to provide a restricted passageway
between the front end of the baffle and the curtain wall.
Preferably, the lower end of the baffle 28 is elevated relative to
the lower end of the curtain wall 26, and the cross-sectional areas
of the vertical passageway 25 and the restricted passageway between
the baffle and the curtain wall are substantially equal. In
addition, the rear end of the baffle wall 28 is provided with a
relief passageway 30 which functions to eliminate any high pressure
zone produced in the scrubber chamber below the baffle.
In the particular construction of the settling chamber 19 as
described, it will be seen that combustion gases emanating from the
combustion chamber will rise and pass through the horizontal
passage 21, downwardly through the vertical passageway 25, around
the lower end of the curtain wall 24 in the scrubber chamber,
describing a curved path, upwardly through the restricted portion
of the vertical passageway 26 and horizontally through the
passageway 27 into the settling chamber. As the stream of gases
flows along such a path through the scrubber chamber, fly ash
particulate having a particle size in the order of five microns and
larger will be removed from the stream of combustion gases
primarily by sprinklers 31 mounted on the lower end of curtain wall
24, which direct a spray of water downwardly across the path of
gases flowing through the scrubber chamber. The sprinklers may be
of any suitable type capable of removing large particulate from the
stream of combustion gases flowing through the scrubber chamber. It
will be appreciated that either the contact of the water spray with
the particulate or the combination of the force of the water spray
and the centrifugal forces acting on the particulate, will cause
the particulate either to precipitate and fall to the bottom of the
scrubber chamber, or to be diverted tangentially from the main
stream of gases flowing through the scrubber chamber and impinge
upon either the partition wall 17 or the baffle 28 which causes
them to lose their kinetic energy and fall to the bottom of the
scrubber chamber. The sprinklers further function to reduce the
temperature of the gas from the order of 1,600.degree. F. to the
order of 600.degree. F. The relief passageway 30 in the baffle 28
is provided to prevent the formation of a high pressure zone below
the baffle 28 which would function to deter fly ash particulate
from being diverted from the main stream of the combustion gases
flowing through the scrubber chamber.
Depending from the upper wall 11 and extending into the settling
chamber 20 is a curtain wall 32. The lower end of the curtain wall
32 projects below the upper level of the partition wall 17 and is
space above the lower wall 12. The curtain wall is spaced from the
partition wall 17 and the rear end wall 14, to provide vertical
passageways 33 and 34 on opposite sides thereof. The vertical
passageway 33 intercommunicates the horizontal passageway 27 and
the settling chamber 20, and the vertical passageway 34
intercommunicates the settling chamber 20, and a flue opening 35
provided in the upper end of the rear end wall 14. With such an
arrangement of components, a stream of combustion gases introduced
through the horizontal passageway 27 will be caused to flow
downwardly through vertical passageway 33, around the lower end of
the curtain wall 32, and upwardly through the vertical passageway
28, describing a curved path having the center of curvature thereof
disposed in the lower end of the curtain wall 32, and horizontally
through the flue opening 35 to be discharged into the
atmosphere.
Extending across the passageway 33 and supported on the end walls
15,15 is a plurality of ionizing electrodes consisting of one or
more electrically conducting wires disposed transversely to the
flow of gases, inside of passageway 33 provided by a plurality of
short grounded plates 36a disposed transversely in passageway 33
and extending in the direction of the flow of gases. A high direct
current voltage in the order of 4 to 10 kv is applied to the
electrodes 36 to produce electrostatic fields of sufficient
strength to provide corona discharges in passageways 33a, which
function to produce an ionizing zone through which combustion gases
introduced through the horizontal passageway 27 are caused to flow.
Disposed downstream from the ionization zone provided by the
electrode 36, is a plurality of curved, electrode supporting plates
37 which are spaced between the lower end of the curtain wall 32
and a curved wall 38 merging at the extremities thereof with the
interior wall surfaces of the partition wall 17 and a portion of
lower wall 17 and a portion of lower wall 12 defining the settling
chamber, thus providing a plurality of curved passageways 39.
Preferably, the support members 37 are constructed of a
nonelectrically conducting material, extend across the entire
length of the settling chamber, are provided with a center of
curvature similar or in the vicinity of the center of curvature of
the path of gases traversing through the settling chamber and are
provided with an airfoil configuration to (a) minimize the
resistance of the support members to the streams of gases flowing
through the settling chamber, (b) maintain an unbroken water film
for the removal of collected particles and gaseous contaminants,
and (c) vary the passage area so as to reduce the gas velocity at
the exit, thereby reducing the probability for re-entrainment of
collected particles. Mounted on the lower end of the curtain wall
32 and the undersides of the support members 37 are curved,
negatively charged plates 40. Spaced from the negatively charged
plates 40 and mounted on the support members 37 and the curved wall
38 of the housing structure is a plurality of grounded collector
plates 41 which cooperate with the negatively charged plates 40
when a high direct current voltage is applied, to produce
electrostatic fields between the sets of electrodes in the
passageways 39.
In the operation of the embodiment illustrated in FIGS. 1 and 2,
when refuse is burned in the combustion chamber 18, a certain
amount of fly ash particulate and gaseous contaminants such as
sulfur oxides, nitrogen oxides, and combined and uncombined
halogens including fluorines, chlorines, etc., will be entrained in
the combustion gases emanating from the combustion chamber and will
flow through passageways 21 and 25, around the lower end of the
curtain wall 24 in the scrubber chamber, and upwardly through the
restricted portion of the passageway 26 into the horizontal
passageway 27. As the stream of combustion gases flows around the
lower end of the curtain wall 24, most of the fly ash particulate
having a particle size in the order of 5 microns and larger will be
removed from the stream of gases flowing upwardly through the
restricted portion of the passageway 26 either by means of the
water spray provided by the sprinklers 31 or a combination of the
force applied by the water spray and the centrifugal forces
produced by the curved motion of the stream of gases, whereby the
large fly ash particulate will either be precipitated or caused to
divert and impinge upon the horizontal baffle 28 or the partition
wall 17 causing the particulate to lose its kinetic energy and fall
to the bottom of the scrubber chamber. The relief passageway 30 in
the rear end of the horizontal baffle eliminates the formation of
any high pressure zone below the baffle which would tend to inhibit
the removal of large fly ash particulate so that the stream of
combustion gases flowing through the horizontal passageway 27 and
introduced into the settling chamber substantially will contain
particulate having a particle size of less than 5 microns.
As the stream of combustion gases continues to flow downwardly
through the ionization zone of passageway 33, particulate entrained
in the stream of gases will be ionized by the corona discharges
produced between the electrodes 36 and 36a. The ionized particulate
is then caused to flow through arcuate passageways 39 and upwardly
through passageway 34 into the flue opening 35. In doing so, the
ionized particulate will be caused to be diverted from the main
stream of gases flowing through the settling chamber by centrifugal
forces produced by the motion of the gas stream, electrostatic
forces produced by the electrostatic fields in the curved
passageways 39, and gravitational forces. The combination of such
forces functions to remove the residual particles entrained in the
stream of gases flowing through the settling chamber.
The electrostatic fields provided between the plates 40 and 41 in
the passageways 39, will cause a substantial portion of the ionized
particles passing through such passageways to be collected on the
collector plates 41. Particulate deposited on the plates 41 is
removed and deposited at the bottom of the settling chamber by
means of washer units 42 which spray a film of water on the
collector plates 41 to wash precipitated particulate from the
surfaces thereof.
Gas molecules which also have been ionized will be forced to the
collector plates 41 whereby those molecules which either dissolve
in or react with the water flowing along the collector plates,
effectively will be removed from the gas stream. Since many of the
undesirable contaminants, particularly sulfur oxides, nitrogen
oxides and combined and uncombined halogens such as chlorine,
fluorine, etc. behave in this manner, the device constitutes an
effective means for the removal of such undesirable gaseous
contaminants from the effluent emitted into the atmosphere by the
incinerator.
It further is contemplated, that certain additives be introduced
into the water used for washing the collector plates, which will
adsorb or chemically react with the contaminants to render the
contaminants harmless and, preferably, produce a form of the
contaminants which would facilitate their removal from the liquid
medium. In addition, it is contemplated that any suitable liquid
medium such as water, with or without an adsorbing or chemically
reactive additive, may be used to wash the collector plates of
precipitated contaminant. Alternatively, the additive may be
introduced into the liquid medium subsequent to the washing of the
collector plates, depending on the nature of the contaminants and
the product of the physical or chemical combination of the
contaminants with the liquid medium.
Since many of the contaminants would chemically react with water
used as a washing medium, it specifically is contemplated that an
additive be introduced into the water which will neutralize any
acid that may be formed by the reaction of the contaminants with
the water, thereby preventing corrosion of the collector plates.
Under such circumstances, an alkaline solution including an alkali
metal hydroxide such as sodium hydroxide or potassium hydroxide or
an alkaline earth metal hydroxide such as calcium hydroxide or
magnesium hydroxide, in solutions ranging from 0.05 percent to 50
percent by weight, would be added to the water utilized as a liquid
washing medium to neutralize the acids formed by the
contaminants.
It is to be understood that the invention contemplates the use of
any suitable liquid washing medium either alone or in physical or
chemical combination with a contaminant treating agent introduced
into the liquid medium either prior or subsequent to the washing
operation, which in any manner, either physically or chemically,
will react with the precipitated molecules of gaseous contaminants
and possibly even with the precipitated particulate, to render the
discharge fluid from the collector plates harmless, thus enhancing
the contaminant removal and protecting the various components of
the incinerator and auxiliary equipment from any corrosive or
deteriorative effects of the discharge liquid.
The curved motion of the various stream of gases flowing through
passageways 39 will cause particulate which has not been deposited
on the plates 41 to be diverted from the recombined stream of gases
flowing upwardly through vertical passageway 34 by means of the
centrifugal, electrostatic and gravitational forces acting on such
particulate. Such particulate along with water droplets entrained
in the recombined gas streams will move along tangential or
involute paths at diminishing velocities until they either fall to
the bottom of the settling chamber or impinge upon the rear end
wall 14 or a horizontal baffle 43 provided in the vertical
passageway 34, causing them to lose their kinetic energy, fall to
the bottom of the settling chamber, and be entrapped in the water
basin provided therein. The front end of the horizontal baffle 43
is spaced from the curtain wall 32 to provide a restricted portion
of the passageway 34 through which the clean gases flow, to be
discharged through the flue into the atmosphere. The formation of a
high pressure zone below the horizontal baffle 43, tending to deter
the separation of particulate from the main stream of gases flowing
upwardly through the restricted portion of passageway 34, is
prevented by means of a relief passageway 44.
Although the settling chamber with its particular configuration and
the electrostatic precipitator, providing a combination of
centrifugal, electrostatic and gravitational forces for removing
solid and gaseous contaminants from the stream of combustion gases
flowing through the settling chamber, would be sufficient to reduce
materially the amount of contaminants emitted into the atmosphere,
it is preferred that fly ash particulate having a particle size in
the order of 5 microns and larger be removed from the combustion
gases prior to introducing the gases into the settling chamber. The
removal of larger particulate enhances the effectiveness of the
settling chamber as described. Furthermore, it is preferred that
primary and secondary combustion chambers be utilized so as to
prolong the resident time of the gases, thus providing maximum
incineration of the refuse and the production of a smaller amount
of fly ash particulate entrained in the combustion gases introduced
into either the scrubber chamber or directly into the settling
chamber. Such an embodiment subsequently will be described.
Referring to FIGS. 3 and 4 of the drawings, there is illustrated a
second embodiment of the invention utilizing a one stage
electrostatic precipitator. The embodiment includes a housing
structure 50 having an upper wall 51, a lower wall 52, a front end
wall 53, a rear end wall 54, and a pair of side walls 55,55. The
walls of the housing structure are either constructed of or lined
on the interior sides thereof with a fire resistant material such
as firebrick and the like. Disposed within the housing structure is
a partition wall 56 consisting of firebrick which is spaced from
the front end wall 53, and a partition wall 57 which is spaced
between the partition wall 56 and the rear end wall 54 to provide a
combustion chamber 58, a gas washer or a scrubber chamber 59 and a
settling chamber 60. The upper end of the partition wall 56
terminates below the upper wall 51 to provide a horizontal
passageway 61.
The front end wall 53, is provided with an opening 62 through which
refuse may be charged into the combustion chamber onto a grate 63
mounted in the lower end of the combustion chamber and spaced from
the lower wall 52. Conventional access openings are provided in the
side walls below the grate 63 for removing ash deposited in the
bottom of the combustion chamber. Although a simple combustion
chamber having a grate for supporting refuse and an opening for
charging refuse in the combustion chamber are shown in FIG. 3, it
is to be understood that any suitable type of combustion chamber
utilizing any type of charging system and grate assembly or stoker
may be used within the scope of the present invention.
Depending from the upper wall 51 and extending into the scrubber
chamber 59, is a curtain wall 64. The lower end of the curtain wall
64 projects below the upper level of the partition walls 56 and 57,
and is spaced from the lower wall 52 to provide vertical
passageways 65 and 66 on opposite sides thereof. The vertical
passageway 65 intercommunicates the horizontal passageway 61 and
the scrubber chamber 59, and the vertical passageway 66
intercommunicates the settling chamber 59 with a horizontal
passageway 67 provided by the termination of the upper end of the
partition wall 57 below the upper wall 51.
Disposed in the vertical passageway 66 and supported on the side
walls 55,55 is a horizontal baffle 68 having the front end 69
thereof spaced from the curtain wall 64 to provide a restricted
passageway between the front end of the baffle and the curtain wall
64. Preferably, the lower end of the baffle 68 is elevated relative
to the lower end of the curtain wall 64, and the cross-sectional
areas of the vertical passageway 65 and the restricted passageway
between the baffle and the curtain wall are substantially equal. In
addition, the rear end of the baffle wall 68 is provided with a
relief passageway 70 to eliminate any high pressure zone produced
in the scrubber chamber below the baffle.
Combustion gases emanating from the burning refuse on the grate 63
in the combustion chamber, will be caused to rise and pass through
the horizontal passageway 61, downwardly through the vertical
passageway 65, around the lower end of the curtain wall 64,
describing a curved path, upwardly through the restricted portion
of the vertical passageway 66, and horizontally through the
passageway 67 into the settling chamber. As the stream of gases
flows along such a curved path through the scrubber chamber, fly
ash particulate having a particle size in the order of 5 microns
and larger will be removed from the stream of combustion gases
primarily by sprinklers 71 mounted on the lower end of the curtain
wall 64 or in the vicinity thereof which direct a spray or curtain
of water downwardly across the path of gases flowing through the
scrubber chamber. The sprinklers may be of any suitable type
capable of removing large particulate from the stream of combustion
gases flowing through the scrubber chamber. It will be noted that
either the force of the water spray or a combination of the force
of the water spray and the centrifugal forces acting on the
particulate as it traverses through the scrubber chamber, will
cause the particulate either to precipitate and fall to the bottom
of the scrubber chamber as it passes around the lower end of the
curtain wall, or impinge upon either the partition wall 57 or the
lower side of the baffle 68. The sprinklers also function to reduce
the temperature of the gases from the order of 1500.degree. F. to
1,700.degree. F. to the order of 400.degree. F. to 600.degree. F.
The relief passageway 70 in the baffle 68 is provided to prevent
the formation of a high pressure zone below the baffle 68 which
otherwise would function to deter fly ash particulate from being
diverted from the main stream of the combustion gases flowing
through the scrubber chamber.
Depending from the upper wall 51 and extending into the settling
chamber 60 is a curtain wall 72. The lower end of the curtain wall
72 projects below the upper level of the partition wall 57 and is
spaced above the lower wall 52. The curtain wall 72 also is spaced
from the partition wall 57 and the rear end wall 54, providing
vertical passageways 73 and 74 on opposite sides thereof. The
vertical passageway 73 intercommunicates the horizontal passageway
67 and the settling chamber 60, and the vertical passageway 74
intercommunicates the settling chamber 60 and a flue opening 75
provided in the upper end of the rear end wall 54. It will be
appreciated that with such an arrangement of components, a stream
of combustion gases introduced through horizontal passageway 67
will be caused to flow downwardly through vertical passageway 73,
around the lower end of the curtain wall 72, and upwardly through
the vertical passageway 74, describing a curved path having a
center of curvature disposed in the lower end of the curtain wall
72, and horizontally through the flue opening 75 to be discharged
into the atmosphere.
Disposed in the lower end of the vertical passageway 73 and in the
main body of the settling chamber 60 is a plurality of curved
support members 76 which are spaced between the lower end of the
curtain wall 72 and a curved wall 77 which merges at the
extremities thereof with the partition wall 57 and a portion of
lower wall 52, thus providing a plurality of curved passageways 78.
Preferably, the support members 76 are constructed of a
nonelectrically conducting material, extend across the entire width
of the settling chamber, are provided with a center of curvature
similar or adjacent to the center of curvature of the path of gases
traversing through the settling chamber, and are provided with an
airfoil configuration to minimize resistance to the gases flowing
through the settling chamber. Mounted on the lower end of the
curtain wall 72 and the undersides of the support members 76, are
curved, negatively charged plates 79. Spaced from the negatively
charged plates 79 and mounted on the upper sides of the support
members 76 and on the curved surface 77, is a plurality of grounded
collector plates 80 which cooperate with the negatively charged
plates 79 when a high direct current voltage is applied to each of
the sets of plates, to produce electrostatic fields between the
sets of electrodes in the passageways 78.
Each of the negatively charged plates 79 is provided with a
plurality of transversely spaced, longitudinally disposed
projecting portions 79a which extend toward the adjacent collector
plate 80. As best illustrated in FIG. 4, each of the projecting
portions 79a has a tapered cross-sectional configuration and a
terminal portion of a relatively small diameter. When a sufficient
voltage is applied to a set of plates 79 and 80, an electrostatic
field of sufficient strength is produced in the passageway 78
between the plates to produce a corona discharge between the
tapered projecting portions 79a of the plate 79 and the collector
plate 80. As hereinafter will be described, the corona discharges
produced across the passageways 78 function to ionize the
combustion gases traversing therethrough, whereupon the ionized
solid contaminants entrained in the gases along with some molecules
of gaseous contaminants will be caused to be precipitated by the
electrostatic fields and deposited on the collector plates 80.
In the operation of the embodiment as illustrated in FIGS. 3 and 4,
when refuse is burned in the combustion chamber 38, a certain
amount of fly ash particulate will be entrained in the combustion
gases emanating from the combustion chamber and will flow through
the passageways 61 and 65, around the lower end of the curtain wall
64 in the scrubber chamber, and upwardly through the restricted
portion of passageway 66 into the horizontal passageway 67. As the
stream of gases flows around the lower end of the curtain wall 64,
large fly ash particulate having a particle size in the order of
five microns and larger will be precipitated from the main stream
of gases flowing upwardly through the restricted portion of
passageway 66 either by means of the force of the water spray
provided by the sprinklers 71, or a combination of the force of the
water spray and the centrifugal force created by the curved motion
of the stream of gases flowing through the scrubber chamber,
whereby large fly ash particulate will either be precipitated or
caused to be diverted and impinge upon the baffle 68 or the
partition wall 57. The relief passageway 70 in the rear end of the
baffle 68 functions to eliminate the formation of any high pressure
zone below the baffle which would tend to inhibit the removal of
large fly ash particulate, so that the stream of combustion gases
flowing through the horizontal passageway 67 and introduced into
the settling chamber, substantially will contain particulate having
a particle size of less than five microns.
The stream of combustion gases entering the vertical passageway 73
is caused to flow downwardly through the curved passageways 78 and
then upwardly through the passageway 74 into the flue opening 75.
In doing so, the particulate entrained in the stream of gases
passing through the passageways 78 will be ionized by the corona
discharges, and will be caused to be diverted from the main stream
of gases flowing through the settling chamber by centrifugal forces
created by the motion of the gas stream, electrostatic forces
produced by the electrostatic fields in the curved passageways 78,
and gravitational forces. The combination of such forces functions
to remove the residual particles entrained in the stream of gases
flowing through the settling chamber and discharged into the flue
opening.
The electrostatic forces provided between the plates 79 and 80 and
the centrifugal forces produced by the motion of the gas stream
will cause a substantial portion of the ionized particles passing
through the passageways 78 to be collected on the collector plates
80. Particulate deposited on the collector plates is removed
therefrom and deposited at the bottom of the settling chamber by
means of washer units 81 which spray a film of water on the
collector plates to wash precipitated particulate from the surfaces
thereof. The washer units 81 are supported by the side walls 55,55,
and are disposed in the leading ends of the curved passageways 78
adjacent to the collector plates 80. Ordinarily, the washer units
will consist of water pipes having discharge openings or nozzles
directed toward the collector plates 80. It is to be understood,
however, that any suitable device may be utilized for washing
particulate deposited on the collector plates.
In addition to solid contaminants being ionized and
electrostatically precipitated from the gas stream as it flows
through passageways 78, molecules of gaseous contaminants also will
be ionized by the corona discharge produced in the passageways 78,
which are electrostatically precipitated. Similar to the action of
the electrostatically precipitated gaseous molecules described in
connection with the embodiment illustrated in FIGS. 1 and 2 of the
drawings, such gaseous molecules will be collected by the liquid
washing medium and carried off therewith. In this embodiment of the
invention, as in the aforementioned embodiment, it is contemplated
to utilize a liquid-washing medium with or without an appropriate
additive which will render nonreactive the collected gaseous and/or
solid contaminants or the product of the gaseous and/or solid
contaminants either physically or chemically combined with the
liquid-washing medium.
The curved motion of the various streams of gases flowing through
the passageways 78 will cause particulate which has not been
electrostatically precipitated, to be diverted from the recombined
main stream of gases flowing upwardly through the vertical
passageway 74, by means of centrifugal, electrostatic and
gravitational forces acting on the particulate. Such particulate
along with droplets of the washing medium will be caused to move
along tangential or involute paths at diminishing velocities until
the particles either fall to the bottom of the settling chamber or
impinge upon the rear end wall 54 or a horizontal baffle 82
provided in a vertical passageway 74, causing them to lose their
kinetic energy and fall to the bottom of the settling chamber. The
front end of the horizontal baffle 82 is spaced from the curtain
wall 72 to provide a restricted portion in the passageway 74
through which the clean gases flow to be discharged through the
flue into the atmosphere. The formation of a high pressure zone
below the baffle 82, tending to inhibit the separation of
particulate from the main stream of gases flowing through the
restricted portion of passageway 74, is prevented by means of a
relief passageway 83 provided in the rear end of the baffle.
As previously mentioned in connection with the embodiment
illustrated in FIGS. 1 and 2, although the settling chamber with
its particular configuration and the electrostatic precipitator,
providing a combination of centrifugal, electrostatic, and
gravitational forces for removing solid and gaseous contaminants
from the stream of combustion gases flowing through the settling
chamber, would be sufficient in the embodiment illustrated in FIGS.
3 and 4 to materially reduce the solid and gaseous contaminant
loading of gases emitted into the atmosphere, it is preferred that
fly ash particulate having a particle size in the order of 5
microns and larger be removed from the combustion gases prior to
introducing such gases into the settling chamber. The removal of
larger particulate enhances the effectiveness of the settling
chamber as previously described. Furthermore, it is preferred that
primary and secondary combustion chambers be utilized so as to
prolong the residence time and thus provide maximum incineration of
the refuse and the production of a smaller amount of fly ash
particulate entrained in the combustion gases introduced into
either the scrubber chamber or directly into the settling
chamber.
Referring to FIGS. 5 and 6, there is illustrated a third embodiment
of the invention. Such embodiment consists of an incinerator
including a housing structure 90 having an upper wall 91, a lower
wall 92, a front end wall 93, a rear end wall 94 and a pair of side
walls 95,95. Similar to the aforementioned embodiments, the various
walls of the housing structure 90 are either constructed of or
lined on the interior side thereof with a fire resistant material
such as firebrick and the like. Disposed within the housing
structure are partition walls 96, 97 and 98 consisting of
firebrick, providing a primary combustion chamber 99, a secondary
combustion chamber 100, a gas washer or scrubber chamber 101 and a
settling chamber 102. The upper wall of the primary combustion
chamber 99 is provided with an opening 103 through which refuse may
be charged into the primary combustion chamber onto a grate 104
mounted in the lower end of the chamber and spaced from the lower
wall thereof. Conventional openings are provided in at least one of
the side walls below the grate 104 for removing ash deposited in
the bottom of the primary combustion chamber below the grate.
Although a simple primary combustion chamber having a grate for
supporting refuse and an opening for charging refuse into the
chamber are shown in FIG. 5, it is to be understood that any
suitable type of combustion chamber utilizing any type of charging
system and grate assembly or stoker may be used within the scope of
the invention.
The partition walls 96 and 97 defining the front and rear walls of
the secondary combustion chamber, terminate below the upper wall 91
to provide horizontal passageways 105 and 106 communicating with
the primary combustion chamber and the scrubber chamber,
respectively. Depending from the upper wall 91 and extending into
the secondary combustion chamber, is a curtain wall 107, the lower
end of which projects below the upper levels of the partition walls
96 and 97. In addition, the curtain wall 107 is spaced from the
partition walls 96 and 97 to provide vertical passageways 108 and
109 on opposite sides thereof communicating with the horizontal
passageways 105 and 106, respectively.
Supported on the side walls 95,95 and disposed in the vertical
passageway 109 is a horizontal baffle 110 having the front end
thereof spaced from the curtain wall 107 to provide a restricted
passageway between the front end of the baffle and the curtain
wall. Preferably, the lower end of the baffle 110 is elevated
relative to the lower end of the curtain wall 107, and the
cross-sectional areas of the vertical passageway 108 and the
restricted passageway between the baffle and the curtain wall are
substantially equal. In addition, the rear end of the baffle wall
110 is provided with a relief passageway 111 which functions to
eliminate any high pressure zone produced in the secondary
combustion chamber below the baffle.
Mounted within the scrubber chamber 101 is a plurality of vertical
cylindrical conduits disposed in side-by-side relation across the
width of the scrubber chamber, as best illustrated in FIG. 6. The
conduits 112 may be secured to the upper wall 91 of the incinerator
housing and extend downwardly into the scrubber chamber, having the
lower ends thereof spaced from the lower wall 92 of the incinerator
housing. The upper ends of each of the conduits 112 are provided
with vertical, elongated openings 113 which are offset relative to
the vertical axes of the conduits, communicate with the secondary
combustion chamber through a duct 114 disposed in horizontal
passageway 106 and the vertical passageway 109, and permit the
entry of combustion gases tangentially into the cylindrical
chambers of the conduits. The lower ends of the conduits 112 are
provided with outlet openings 115 which are axially spaced relative
to the inlet openings 113, and which communicate with the scrubber
chamber. In addition to being located at the lower ends of the
conduits 112, the outlet openings 115 also may be disposed on the
lower sides of the conduits. It will be noted that gases introduced
into the conduits 112 tangentially, will be caused to traverse the
lengths of the conduits in a helical or swirling motion, and be
ejected through the outlet openings 115 into the lower end of the
scrubber chamber 101.
Disposed in the upper end of each conduit 112 is a sprinkler or
spray unit 116 which functions to spray or sprinkle water
downwardly along the interior sides of the conduits 112. Each of
the spray units 116 is connected to a fluid supply line, and is
provided with a shut-off valve so that selected spray units may be
placed into or removed from service as desired. Water discharged
through the lower ends of the conduits 112 is collected at the
lower end of the scrubber chamber which functions as a trough,
which may be returned to the sprinkler units for recirculation
through the system. Additional means may be provided for adding
fresh make-up water to the sprinkler system and to drain the lower
end of the settling chamber for repairs or routine maintenance.
The partition wall 98 and the rear end wall 94 form the front and
rear walls of the settling chamber 102. The upper end of the
partition wall 98 terminates below the upper wall 91 to provide a
horizontal passageway 117 communicating with the scrubber chamber
101. The rear end wall 94 is provided with an opening 118
communicating with the flue of the incinerator.
Depending from the upper wall 91 and extending into the settling
chamber 102 is a curtain wall 119. The lower end of the curtain
wall projects below the upper level of the partition wall 98 and is
spaced above the lower wall 92 of the incinerator. The curtain wall
119 is spaced from the partition wall 98 and the rear end wall 94
to provide vertical passageways 120 and 121 on opposite sides
thereof. The vertical passageway intercommunicates the horizontal
passageway 117 and the settling chamber 102 and the vertical
passageway 121 intercommunicates the settling chamber with the flue
opening 118. With such an arrangement of components, a stream of
combustion gases introduced through the horizontal passageway 117
will be caused to flow downwardly through vertical passageway 120,
around the lower end of the curtain wall 119, and upwardly through
the vertical passageway 120, describing a curved path having the
center of curvature thereof disposed in the lower end of the
curtain wall 119, and horizontally through the flue opening 118 to
be discharged into the atmosphere.
Disposed in the lower end of the vertical passageway 118 and in the
main body of the settling chamber 102 is a plurality of curved
support members 122 which are spaced between the lower end of the
curtain wall 119 and a curved wall 123 which merges at the
extremities thereof with the partition wall 98 and a portion of the
lower wall 92, thus providing a plurality of curved passageways
124. Preferably, the support members 122 are constructed of a
nonelectrically conducting material, extend across the entire width
of the settling chamber, are provided with a center of curvature
similar or adjacent to the center of curvature of the path of gases
traversing through the settling chamber, and are provided with an
airfoil configuration to minimize resistance to the gases flowing
through the settling chamber. Mounted on the lower end of the
curtain wall and the undersides of the support members 122, are
curved, negatively charged plates 125. Spaced from the negatively
charged plates 125 and mounted on the upper sides of the support
members 122 and on the curved surface 123, is a plurality of
grounded collector plates 126 which cooperate with the negatively
charged plates 125 when a high direct current voltage is applied to
each of the sets of plates, to produce electrostatic fields between
the sets of electrodes and the passageways 124.
Similar to the construction of the negatively charged plates 79
described in connection with the embodiment illustrated in FIGS. 3
and 4, each of the negatively charged plates 125 is provided with a
plurality of transversely spaced, longitudinally disposed
projecting portions which extend toward the adjacent collector
plate. The projecting portions have tapered cross-sectional
configurations and terminal portions of a relatively small
diameter. As previously described in connection with the embodiment
illustrated in FIGS. 3 and 4, when a sufficient voltage is applied
to a set of plates 125 and 126, an electrostatic field of
sufficient strength is produced in each passageway 124 between the
plates to produce a corona discharge between the tapered projecting
portions of the negatively charged plates 125 and the collector
plates 126. The corona discharges produced across the passageways
124 function to ionize the combustion gases traversing
therethrough, whereupon ionized fly ash particles entrained in the
gases along with some molecules of gaseous contaminants will be
caused to be precipitated by the electrostatic fields and deposited
on the collector plates 126.
In the operation of the embodiment illustrated in FIGS. 5 and 6,
when refuse is burned in the primary combustion chamber 99, the
gaseous products of combustion at least to some extent will
continue to burn as they flow through horizontal passageway 105,
and downwardly through vertical passageway 108 and around the lower
end of the curtain wall 107 in the secondary combustion chamber. As
the burning gases flow around the lower end of the curtain wall 107
and through the restricted passageway between the front end of the
baffle 110 and the curtain wall 107, centrifugal forces acting on
fly ash particles entrained in the gases will cause the fly ash
particles to be diverted from the main stream of gases, and follow
tangential or involute paths toward either the partition wall 97 or
the horizontal baffle 110. Fly ash particles thus diverted from the
main stream of the combustion gases and impinging upon the
partition wall 97 or the baffle 110 will be caused to lose their
kinetic energy and fall to the bottom of the secondary combustion
chamber to be removed by conventional means. The relief passageway
111 in the rear end of the horizontal baffle 110 prevents the
formation of any high pressure zone in the secondary combustion
chamber below the baffle 110 which possibly would result in
re-entrainment of fly ash particles previously diverted from the
main stream of gases traversing through the secondary combustion
chamber. The secondary combustion chamber thus functions to prolong
the burning of fly ash particles and, through the use of
centrifugal and gravitational forces, to remove fly ash particles
having a size in the order of 50 microns and greater, prior to
introducing the combustion gases into the scrubber chamber.
The gases tangentially entering the conduits 112 through inlet
openings 113 will be caused to traverse through the conduits in a
helical or swirling motion. As the gases traverse through the
conduits 112 with such a motion, to be ejected through the outlet
opening 115, they will contact the stream of water injected into
the conduits by the spray units 116. The contact of such gases with
the film of water flowing downwardly along the inner sides of the
conduits will cause fly ash particles having a size in the order of
5 microns and greater to become separated from the combustion gases
and be carried by the water downwardly into the trough at the lower
end of the scrubber chamber. The conduits 112 further function to
reduce the temperature of the gases from the order of 1,600.degree.
F. to the order of 600.degree. F.
The stream of combustion gases flowing upwardly in the scrubber
chamber 101, through horizontal passageway 117 and downwardly
through vertical passageway 120, is caused to flow downwardly
through the curved passageways 124 and then upwardly through the
passageway 121 into the flue opening 118. In so doing, particulate
and some of the gaseous contaminants entrained in the stream of
gases passing through the passageways 124 will be ionized by the
corona discharges, and will be caused to be diverted from the main
stream of gases flowing through the settling chamber by the
centrifugal forces created by the motion of the gas stream,
electrostatic forces produced by the electrostatic fields in the
curved passageway 124, and gravitational forces. The combination of
such forces functions to remove the residual particles and some of
the gaseous contaminants entrained in the stream of gases flowing
through the settling chamber and discharged into the flue
opening.
The electrostatic forces acting in passageways 124 and the
centrifugal forces produced by the motion of the gas stream, will
cause a substantial portion of the ionized particles passing
through the passageways 124 to be collected on the collector plates
126. Particulate deposited on the collector plates is removed
therefrom and deposited at the bottom of the settling chamber by
means of washer units 127 which spray or sprinkle a film of water
on the collector plates to wash precipitated particulate and
molecules of gaseous contaminants from the surfaces thereof. The
washer units 127 are supported by the side walls 95,95 and are
disposed in the leading ends of the curved passageways 124 adjacent
the collector plates 126.
In addition to particulate being ionized and electrostatically
precipitated from the gas stream as it flows through the
passageways 124, molecules of gaseous contaminants also will be
ionized by the corona discharge produced in the passageways 124,
which will be electrostatically precipitated. As described with the
aforementioned embodiments, such gaseous molecules will be
collected by liquid washing medium and carried off therewith. It
further is contemplated to utilize a liquid medium with or without
an appropriate additive which will render nonreactive the collected
solid and/or gaseous contaminants or the product of the solid
and/or gaseous contaminants either physically or chemically
combined with the liquid washing medium.
The curved motion of the various streams of gases flowing through
the passageways 124 will cause particulate which has not been
electrostatically precipitated, to be diverted from the recombined
main stream of gases flowing upwardly through the vertical
passageway 121 by means of centrifugal, electrostatic and
gravitational forces acting on such particulate. Such particulate
along with droplets of the washing medium, will be caused to move
along tangential or involute paths at diminishing velocities until
the particles and droplets either fall to the bottom of the
settling chamber or impinge upon the rear end wall 94 or a
horizontal baffle 128 provided in the vertical passageway 121,
causing them to lose their kinetic energy and fall or flow to the
bottom of the settling chamber. The front end of the horizontal
baffle 128 is spaced from the curtain wall 119 to provide a
restricted portion of the passageway 121 through which the clean
gases flow, to be discharged through the flue into the atmosphere.
The formation of a high pressure zone below the baffle 128, tending
to cause diverted particulate to become re-entrained in the main
stream of gases flowing through the restricted portion of the
passageway 121, is prevented by means of a relief passageway 129
provided in the rear end of the baffle.
In the embodiment illustrated in FIGS. 5 and 6 of the drawings, it
will be noted that a series of combinations of forces are applied
to the solid and gaseous contaminants entrained in the products of
combustion emanating from the primary combustion chamber to reduce
the solid and gaseous contaminant loading of the effluent emitted
into the atmosphere to a loading approaching that of the ambient
atmosphere. It specifically is to be noted that the secondary
combustion chamber functions to increase the resident time of the
gases to produce complete combustion and apply a combination of
centrifugal and gravitational forces to remove solid particles
having a particle size of 50 microns and greater, the scrubber
chamber utilizes centrifugal and gravitational forces in
conjunction with the physical and chemical combination of a film of
water with the contaminants to remove particulate having a particle
size of 5 microns and greater and to reduce the concentration of
gaseous contaminants of the gas, and the settling chamber applies a
combination of centrifugal, electrostatic and gravitational forces
to reduce the solid and gaseous contaminants of the effluent
emitted into the atmosphere.
In the various embodiments of the invention as described, it has
been mentioned that particulate deposited on the collector plates
of the electrostatic precipitator may be removed by washing the
collector plates with a film of water. In this respect, it is
contemplated that the particulate deposited on the collector plates
also may be removed by other suitable means including vibrating the
collector plates. It further is contemplated that alternate
configurations of the electrodes of the electrostatic precipitator
may be utilized including a plurality of rectilinear plates and a
plurality of curved plates having tangential trailing ends which in
either instance would still cooperate with other designed features
of the housing structure to impart a curved motion on the stream of
combustion gases passing through the settling chamber. Although in
the aforementioned embodiments the electrodes have been described
as being negatively charged, it is within the scope of this
invention to utilize either negatively or positively charged
electrodes. It further is contemplated that each of the chambers
wherein contaminants are precipitated, optionally be provided with
wet bottom basins for entrapping precipitated contaminants.
There are several advantages which accrue from the plurality of
curved passageways utilized in each of the aforementioned
embodiments, wherein solid and gaseous contaminants are subjected
to combined centrifugal, electrostatic and gravitational forces.
The centrifugal force produced by the curved motion of the gases
traversing the passageways positively maintains the films of liquid
washing medium on the collector plates. This considerably reduces
the tendency of the various films of liquid washing medium to break
up due to both electrostatic forces resulting from high collecting
fields and air flow shear forces caused by high gas stream
velocities. This feature alone offers the possibility of exceeding
by a significant degree the usual 20 to 25 feet/seconds maximum gas
velocities used in conventional electrostatic precipitator systems,
thereby enhancing the liklihood for eliminating the necessity of
any mechanical cleaning of the electrodes. Further, since the
centrifugal field maintains smooth films of liquid washing medium
over the curved collector plates and also keeps larger particles
off the repeller plates, it is likely that considerably high
collector-section fields can be maintained; e.g., possibly as high
as 7 kv/cm.
A further advantage of the plurality of curved passageways is that
the variable flow passageway area through which the gases are
conducted permits a substantial reduction in gas velocity near the
trailing ends of the passageways thus reducing the tendency for
re-entrainment of the water dripping off of the collector plates.
Pressure drop through the system also is improved by the
aerodynamic shaping which produces favorable boundry-layer pressure
gradients over half the plate area, as well as low-loss inlet and
exit flow configurations and smooth surfaces on the collector
plates, i.e., the films of liquid washing medium, to reduce
friction-factor losses.
In the reduction of solid wastes by incineration, ideally it has
been sought to provide an incinerator design which is effective in
reducing solid wastes to a minimum volume with minimum power
consumption and without unduly impairing the structural integrity
of the incinerator, and emitting an effluent into the atmosphere
having a solid and gaseous contaminant loading approaching the
loading of the ambient atmosphere. It is contemplated that the
aforementioned invention is operable to both economically reduce
refuse to a minimum volume and, to produce an effluent emission of
a sufficient quality to minimize both solid and gaseous
contamination of the atmosphere.
From the foregoing detailed description, it will be evident that
there are a number of changes, adaptations and modifications of the
present invention which come within the province of those skilled
in the art. However, it is intended that all such variations not
departing from the spirit of the invention be considered as within
the scope thereof as limited solely by the dependent claims.
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