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Патент USA US2403545

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July 9, 1946.
A. NUTTING
2,403,545 _
DUST ARRESTER LIQUID LEVEL CONTROL
0
Filed June 5, 1943
Fig. 1.
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INVENTOR
ARTHUR Nun-mg
‘BY (blew W
ATTORNEY
Patented July‘ 9, 1946
~ 2,403,545
UNITED STATES PATENT OFFICE ~
I
_ DUST ARREsTERzljoQslflif LEVEL CONTItOL
‘Arthur Nutting, Louisville, Ky” assignor to Ameri
.
p
can'Air Filter Company, Inc.,ILouisville, Ky., a
corporation or Delaware
Application June 5, 1943, ,Serial No. 489,857
8 Claims.
(Cl. 183-24)
1 .
There are presently available a number of dif- I
ferent dust arresters of. the type wherein air
passes downwardly through the inlet air side of
thearrester and impinges against a water bath
as it turns to pass upwardlythrough a ba?le zone
into the clean air side thereof, the air propelling
a stream of water into the battle zone at a rate
depending upon the velocity of the air and the
"head" of water available in the impingement
2
Now when the make-up water is added to raise
the de?cient operating level to the normal low
level for the predetermined air ?ow, too much
water becomes available for the increased air flow.
As a result, the arrester is more or less ?ooded
and its resistance greatly increased. The in
creased resistance, of course, cuts down the. air
flow somewhat but an equilibrium will be estab
area. Dust arresters of this general type are de 10 lished with an excess flow of both air and water
at the normal low operating level.
signed for operation at a predetermined air ?ow
On the other hand, should the air ?ow rapidly
and provided with a predetermined static liquid
decrease from the excess ?ow to normal, the low
level. When operation is instituted, the static
operating level surges upwardly above the normal
level drops on the inlet side and rises on the out
let side, reaching the proper operating level when 15 level supplying excess water to the battle zone for
an interval depending upon the drainage rate of
the proper air ?ow is reached. At the proper air
the excess water.
flow, the proper operating level on the inlet side
Should the air flow rapidly decrease below nor
provides an available “head" of proper proportion
mal, the low operating level again surges above
and thus insures a proper water flow. Since some
water is lost during operation, it is customary to 20 normal but is ultimately returned to normal as ‘
the Water drains. When the normal low operat_
ing level is restored with a de?cient air flow, a
de?cient .water ?ow results.
'
level correspondingto the proper air ?ow.
A more important objection arises when the ar
Generally speaking, these controls are designed
install a water level control on the inlet side of
the arrester in order to maintain an operating
to add make-up water to the bath when the low
operating level falls below normal and to drain '
rester is installed and operated at a constant air
?ow above or below the predetermined ?ow for
water from the bath when it rises above normal.
They have not been entirely satisfactory for a
number of reasons. For example, the drains clog
which it was designed. This Often occurs in serv
prevent the Water from rising to the static level
will attempt to maintain the normal low opera“
ice due to various reasons. For example, it is not
uncommon to ?nd the user installing, with the
from time to time. Also the controls waste con 30 arrester, a fan or blower either larger or smaller
siderable water when the arrester is shut down
than the one recommended for the arrester.
due to the fact that the drainage outlet is set at
When this occurs the fan or blower will tend to
the low operating level and therefore tends to
maintain an abnormal air ?ow while the controls
unless the drain is closed at that time by a valve. 35 ing level. As a. result, too much or too little water
Since this valve should be operated automatical
is supplied rendering the operation of the arrester
ly, its provision increases the amount of control
unsatisfactory until the controls are readjusted.
equipment necessarygwhile dirt often prevents the
This usually necessitates one or more service calls
automatic closure of the drain.
_
by the manufacturer of the dust arresting equip
Another objection to this type of control arises 40 ment, although the fault was not occasioned by
his equipment.
In summary, it may be said that the foregoing
For example, should the air ?ow rapidly increase
water level controls permit satisfactory operation
to a value substantially above normal, the low 0p
of the dust arrester only when the air flow varia
' ‘crating level will rapidly drop to a value substan 45 tions are held within narrow limits, and, beyond
from its inability to cope with substantial varia
tions in the air ?ow from the predetermined ?ow.
. tially below normal.
As it drops, there is a‘ mo
-mentary surge of excess water into the baille zone‘.
When it reaches the lower level, there is a‘ de
f ?cient water ?ow. Assuming the excess air flow
‘continues inde?nitely, the de?cient water ?ow 50
4‘ will: last for a period of time depending upon the
speed with which the control adds'make-up water
vand during that time the arrester will certainly
operate ine?iciently and may operate, more or less
such limits, cause de?cient and excess water ?ows
with de?cient and excess air flows. The present
invention relates to an improved water level con
trol.
-
The principal object is to provide a control
which not only avoids most, if not all, of the fore
going objections, but also maintains good operat
ing conditions generally, and good water ?ow
conditions speci?cally, over a wide range of air
'- -vdr_y. long enough to cause the arrester to clog up. 66 ?ows.
2,403,545
3
‘
arcuately downward into the bath on the clean
Another object is to provide an extremely simple
and relatively tool-proof control.
air side.
Under normal conditions of operation, with the
predetermined air flow passing through the ar
A further object is to provide, in a water-level
control having a drainage outlet communicating
rester, a substantially continuous stream 01 water
will flow from the low level side to the high level
with the liquid bath of an arrester, a make-up
water supply which is interposed between the
drain and bath whereby relatively little dirt or
sludge is carried into the drain and clogging of
side through the ba?le zone at a substantially
constant rate sui?cient to form continuous ?lms
and curtains. With prior low level controls, when
the drain is correspondingly prevented.
A further object is to provide openly-accessible, 10 the air either flows continuously at some other
readily - removable,
drain - protecting
rate or otherwise varies from the predetermined
rate, the water flow varies likewise occasioning
screens
whereby the incentive for maintenance is pro
meted.
the operating difficulties heretofore mentioned. '
‘
An embodiment of the invention is illustrated
in the accompanying drawing wherein:
Figures 1 is vertical section showing the rela
tion or the control to a suitable form of arrester;
Figure 2 is a side elevation of the control mech
anism taken at right angles of Figure 1;
Figure 3 is an exaggerated view illustrating 20
changes in water level on the low level side of
the arrester; and
I have discovered that these dl?iculties may be
substantially eliminated, and a wide range of air
flows accommodated, simply by controlling the
normal omrating level on the high side while
permitting the level on the low side to vary at
will. While this may be done in various ways, it
can be accomplished simply and effectively by
combining an over-?ow weir on the high side
with suitable means for maintaining a small and
continuous stream of make-up water preferably
supplied adjacent the weir. Furthermore, while
the weir may be positioned at one side of the
7 control in relation to the resistance correspond 25
bath. it preferably is arranged in a chamber
ingly of the same arrester equipped with a water
separate and apart from. but having liquid-sealed
level control on the dirty side and also indicating
communication with, the bath with the make-up
the wide air-flow limits of the arrester with my
water discharging into the chamber preferably
control.
some point between the bath and the weir.
The control is illustrated in connection with an 30 at Accordingly,
I provide a control box it which
arrester l of the type described and illustrated in
is divided by two vertical partitions into three
my co-pendlng application ?ied September 15,
vertical chambers comprising: a low level or
1942, and serially numbered 458,426, new Patent
screen chamber H, a high level or weir chamber
.No. 2,373,330, dated April 10, 1945. In this ar
l2, and a third compartment which is addition
rester, a stream or column of air flows down 35
ally divided by a horizontal partition into an
wardly through inlet chamber 2 and impinges
upper over?ow compartment l3 and lower drain
Figure 4 is a graph showing the resistance
characteristic of an arrester equipped with my
against the upper surface of water bath 3 as it
turns to enter the slot-like entrance of the baiile
zone formed by baiiies 4 and 5 which form part
of a structure dividing the upper portion of the
bath into high pressure and low pressure (or suc
tion) sides and dividing the air space overlying
the bath into an inlet chamber 2 and an outlet
chamber 6. The air passes upwardly through
the air cleaning conduit formed by bailles l and
6 in the ba?le zone and discharges into out
let chamber 8. The ba?les 4 and 5 constrain the
air column in the ba?le zone, to pass in the form
of a ribbon from the slot entrance upwardly along
a path of s-shape. The air moves along the
S-path at a velocity effective to subject the ribbon
of air to intensive centrifugal action in both the
upper and lower halves of the S-path.
As the air flow rises from zero to normal, when
operation is first instituted, the static level drops
on the inlet side, and rises on the outlet ‘side,
age chamber 94. The screen chamber ll openly
communicates at its lower end with the bath 3
40 and at its upper end with the atmosphere so that
its water level will rise and fall with the oper
ating level on the low side of the cleaner. When
the inlet chamber 2 is exposed to atmosphere,
the screen chamber level will be the same as the
45 low operating level, but when the inlet chamber
respectively to the normal low and high operat
ing levels indicated. the di?erence between which
is connected to a duct, these levels will be differ
cut by an amount corresponding to the resistance
of the duct.
'
The weir chamber l2 openly communicates at
50 its lower end with the lower end of the screen
compartment II and, through it, with the bath
3. This chamber could, of course, communicate
directly with the bath but an interposed screen
compartment II is preferred in order to provide
55 between the weir chamber and the bath, a con
venient space to accommodate a dewatering
louver l5 and a pair of screens I8, all of which
may be readily removed through the open top of
the screen chamber II. A weir I1 is interposed
is proportional to the resistance of the baille zone. 60 between (weir and over?ow): compartment 12 and
The ?ow of air further depresses the normal low 7
chamber l3, which openly communicate with each
operating level adjacent the entrance to the
other above the weir and which are not only
S-path, causing such level to assume a slope of
sealed, at the top, by a plate I! but placed in
communication with the outlet air space 8 on
the character indicated. The head h created by
this depression tends to maintain a continuous 65 the clean air side of the arrester by a pipe 19.
With this arrangement, the level in the weir
and relatively constant free ?ow of water into the
compartment l2 rises and falls with the level
entrance of the path. The air ?ow propels this
on the high side of the arrester, while the over
stream of water upwardly entirely through the
?ow passes over weir l1 into the over?ow cham
path and, in doing so, forces the stream to new
in the form of a water ?lm, along each concave 70 ber l3.
The bottom of over?ow chamber l3 communi
wall in each half of the path to the upper end
cates, through an over?ow standpipe 20, with the
or each half, and in the form of a water curtain,
bottom of drainage chamber ll, which contains
across the air column from the end of each half,
a liquid seal II, for the lower end of the stand
the ?rst curtain extending to the beginning or
75 pipe 20, and an over?ow outlet 2! leading from
the second film and the second curtain projecting
2,408,545
the upper levels of the liquid seal through a
three-way valve 23, in its "run" position, to the
is decreased to a subnormal value (see Fig. 3).
In fact, the decrease in the head It is greater with
high level control than it'would be without level
control. For example, without level control, the
sewer. The upper end of drainage chamber I I is
open to atmosphere. with this arrangement, the
liquid level in the standpipe 20 is a measure of
low level drops and the high level rises, to values
the total pressure of the system plus the air ?ow
such that their di?’erence is proportional to the
resistance encountered in the baffle zone.
The make-up water is supplied from a supply
pipe 24 through a strainer 25 and solenoid valve
26, the solenoid of which is electrically connected
(by means not shown) to open and close the
resistance of the battle zone. With high level
control, the high level cannot rise above normal;
hence the low level must continue to drop until
the difference between levels again becomes pro
portional to the baliie zone resistance.
valve automatically when the operation of the
arrester is started and stopped respectively. The
normally open solenoid valve 26 is adjusted to
permit a small continuous stream of make-up
water to ?ow. While the make-up water may
be introduced at any point, it is arranged to dis
charge through opening 21 at a point between
?ow. Consequently, there will normally be a
continuous flow of clean water from opening 21
to both the bath 3 and the weir l1.
The supply pipe 24 is also connected through
a normally closed manually operable valve 28 to
discharge through opening 29 into the weir cham
.
sively increases through the supernormal range,
the water ?ow progressively decreases until an
upper air ?ow limit is reached at which the water.
?ow becomes de?cient. The decrease in water
the screens l6 and the weir IT. The make-up
water is supplied at a rate, su?icient, under nor 20
mal operating conditions, to compensate for evap
oration and to provide a small continuous over
.
The net effect is that, as the air ?ow progres
?ow, however, proceeds at a slow rate so that.
the upper air ?ow limit is substantially above the
normal air flow.
_
When the air ?ow falls below the predeter
mined rate, the low level rises above and the high
level falls below the normal operating levels. The
over?ow now ceases until the make-up water
restores the high level. When the high level is
restored, the low level is slightly increased over
what it would otherwise be. Here again the same
?actors affect the rate at which water ?ows
through the battle-zone. For example: the sub
ber l2. This latter supply provides a rapid ?ow
normal air?ow propels the "available” water at
of water for the purpose of ?lling the arrester
when it is empty. The arrester may be emptied 30 a slower rate; while the rise in the low level _
caused by the subnormal air ?ow and the addi
in any suitable way as through drainage outlet 30
tional rise in that level, caused by the restora
leading from the weir compartment l2 through
tion of the deficient high level to normal, in
the three-way valve 23. The valve 23 in its
creases the head h, rendering more water "avail
“drain” position connects the drainage outlet 30
able.” The net effect is that, as the air ?ow
to the sewer and in its “run” position connects
the over?ow outlet 22 to sewer.
I
progressively decreases through the subnormal
. range, the water ?ow progressively decreases un
_
When the arrester is ?rst installed, the valve
til a lower limit is reached at which the water
23 is placed in the “run" position, connecting the
flow again becomes de?cient. Here again, how
over?ow to the sewer, and the valve 28 opened to
supply bath water. When the water reaches the .40 ever, the decrease in water ?ow proceeds at a
slow rate so that the lower air ?ow limit is sub
static level, the valve 28 is closed and thereafter
remains closed except for bath water supply pur- ' stantially below the normal flow.
The effect of a high level control may be illus
poses. When the fan '(not shown) is started,
air will be drawn through the arrester and, as 45 trated by reference to the curves shown in Figure
suming
4. Here curve N indicates the resistance char
that the air flows at the predetermined
acteristic of an arrester of the type shown in
value for which the arrester was designed, the
bath water level will fall on the inlet or low side
and rise on the outlet or high side to the normal
Figure 1 equipped with the aforesaid high level
control, while graph W indicates the rate of wa
low and high operating levels indicated in the 50 ter ?ow. The predetermined air ?ow for this
C. F. M. At this ?ow, maxi
drawing. The solenoid valve 26 opens, simul
mum water ?ow conditions were obtained while
taneously with the institution of fan operation,
the resistance, in inches of water, was 4.65. Good
to supply small continuous streams of water to
Water ?ow conditions were still maintained when
the bath 3 and the weir chamber l2 and, so long
the ?ow varied over a range of 800 C. F. M. ex
as the high level coincides with the upper edge
of the weir I1, the weir portion of the make-up
water will simply pass upwardly through the weir
water ?ow conditions were maintained over this
chamber l2 and over?ow continuously into the
wide range is indicated by the resistance which
over?ow chamber l3.
.
increased .85" from 4.25” at 600 C. F. M. to 5.1"
Should the air ?ow rise above the predeter
mined value, the operating level on the low side 60 at 1400 C. F. M. As indicated by the dotted curve
L, this same variation of .85" in resistance
will fall below normal, while that on the high
was obtained, in the same arrester equipped with
side will tend to rise above normal creating ex
a low level control, over a range of 60 C. F. M.
cess water which quickly drains overthe weir I1.
As a result of the foregoing action, the rate, at 65 extending from a low limit of 970 C. F. M. to a
high limit of 1030 C. F. M. The curve L also
which water ?ows from the low level through
shows the resistance varying from 3.0" at 855 /
the baiiic zone to the high level, is affected by
C. F. M. to 6.5" at 1090 C. F. M., a resistance vari
changes in the ?ow of air and the head h.
Since the flow of air has increased to a super
ation of 3.5" with an air ?ow variation of 235
C. F. M. All of the foregoing values are, of course,
normal value, the water ?ow “tends” to increase 70 approximate.
'
because the air propels the “available” water
The high level control illustrated has the fur
through the ba?ie zone at a faster rate.
ther advantage of supplying make-up water be
On the other hand, since the low operating
tween the bath 3 and the weir I1. This/normally
level has dropped to a subnormal value, the wa
ter ?ow “tends” to decrease because the head h 75 maintains a ?ow of water into the bath, substan
tially minimizes the reverse ?ow of bath water
2,408,545
8
7
,
‘
liquid from the high level side of the bath when
the high level tends to exceed the predetermined
into the drainage end of the control and corre
spondingly avoids the clogging of the drains.
Furthermore, when bath water does ?ow into the
weir compartment, the louver reduces the dis
turbance oi the sludge and settled material in the
value; and make-up means for supplying make
up water to raise the high level side of the bath ,
to said predetermined value.
.
2. The combination of claim 1 wherein the
bath proper while the screens operate to strain
the water and thus minimize the amount of dirt
drainage 'means comprises an over?ow weir ar
ranged to over?ow at said predetermined level.
carried over to the sewer. The maintenance of
3. The combination of claim 1 wherein: the
the screens and louvers is promoted by the ease
make-up meansis arranged to supply a continu
10
with which they may be removed from and re
ous stream of make-up liquid during the operation
placed in the screen chamber.
'
of the arrester; and means are provided opera
For the sake of ‘clarity in the claims, the high
pressure or low level side of the bath is desig
tively to connect and disconnect said make-up
means at the beginning and end of each operative
nated as either or both the pressure side and the
period of said arrester.
15
low level side while the low pressure or high level
4. The combination with a dust arrester of the
side is designated as either or both the suction
type comprising: a casing wherein an air stream
side and the high level side.
or column is adapted to move downwardly
Having described my invention, I claim:
through an air inlet chamber to impinge against
1. The combination with a dust arrester of the
a bottom liquid bath as it turns to enter and pass
type comprising: a casing wherein an air stream 20 upwardly through a ba?ie zone and thence into
or column is adapted to move downwardly
an outlet chamber; an element and member
through an air inlet chamber to impinge against
mounted on the casing and constructed and ar
a bottom liquid bath as it turns to enter and pass
ranged to de?ne, in said zone, the opposite sides
' upwardly through a baiiie zone and thence into an
of an upright S-shaped air-cleaning conduit oi
outlet chamber; an element and member mounted 25 slot-like cross-sectional area constraining the air
on the casing and constructedand arranged to
to pass through said zone in the form of a shal
low sinuous ribbon from a slot-like air inlet at
de?ne, in said zone, the opposite sides of an up
right sinuously-curved air-cleaning conduit of
the bottom of the zone which communicates hori
zontally with the air inlet chamber to an air
to pass through said zone in the form of a shal 30 outlet slot at the top of the zone which discharges
low sinuous ribbon from a slot-like \air inlet at
the air laterally into the outlet chamber at an
the bottom of the zone which communicates
angle to the vertical, said element extending up
horizontally with the air inlet chamber to an air
wardly in position to divide the upper portion of
outlet slot at the top of the zone which dis
the bath into pressure and suction sides having
slot-like cross-sectional area constraining the air
charges the air laterally into the outlet chamber 35 operating levels respectively below and above the
at an angle to the vertical, said element extend
static level of the bath and being arranged to
ing upwardly in position to divide the upper por
present a concavely-curved air-directing wall
tion of the bath into pressure and suction sides
having operating levels respectively below and
above the static level of the bath and being ar
ranged to present a concavely-curved air-direct
which defines the convex side of the lower half
of said conduit and which slopes, at its lower
40 end, downwardly into the bath to form the lower
ing wall which de?nes the convex side of ‘the
lowermost curved portion of said conduit and
which slopes, at its lower end, downwardly into
side of said inlet slot at a level providing, at the
slot entrance, a head of liquid which progressively
decreases as the air flow through the conduit
progressively increases through its operating
the bath to form the lower side of said inlet slot 45 range, said member extending upwardly in posi
at a level providing; at the slot entrance, a head
tion to divide the air space above the bath into
oi‘ liquid which progressively decreases as the air
said air inlet and outlet chambers and being ar
?ow through the conduit progressively increases
through its operating range, said member extend
irig upwardly in position to divide the air space
above the bath into said air inlet and outlet cham
ranged to present an air-directing wall having
a convexly-curved section forming the concave
bers and being arranged to present a lower con
vexly-curved air-directing wall forming the con
the upper half of said conduit; the arrester being '
cave side of said lowermost curved portion of said
conduit, and an upper concavely-curved air-di
recting wall forming the convex side of the up
permost curved portion of said conduit; the ar
rester being designed to receive an operating
range of air ilows which tend to lower the bath
level on the pressure side and raise it on the suc
side of said lower half of said conduit and a con
cavely-curved section forming the convex side of
designed to receive an operating range of air
55 ?ows which tend to lower the bath level on the
pressure side and raise it on the suction side in
proportion to the air ?ow resistance of conduit
and which operate to' propel a stream of liquid
from the lower level or pressure side of the bath
through the conduit into the outlet chamber;
of control means for maintaining the suction side
of the bath at a predetermined high level during
such operating air ?ows while permitting the low
tion side in proportion to the air flow resistance
of conduit and which operate to propel a stream
of liquid from the low level or pressure side of
level on the pressure side or the bath to vary at
the bath through the conduit into the outlet
will, said control means being operative to cause
65
chamber; of control means for maintaining the
the volume of the liquid stream in the conduit to
suction side of the bath at a predetermined high
increase progressively to a maximum and then
level during such operating air ?ows while per
decrease progressively from the maximum as the
mitting the low level on the pressure Side of the
air flows increase progressively through its op
bath to vary at will, said control means being
erating range, said control means including:
70
operative to cause the volume of the liquid stream
means providing a high level compartment sepa
in the conduit to increase progressively to a maxi
rate from the bath but having a liquid column
mum and\then decrease progressively from the
which joins the bath liquid and an overlying air
maximum as the air ?ow increases progressively
space which is connected to said air outlet cham
through its operating range, said control means
75 ber and subject to the air pressure thereof so
including: drainage means for draining excess
2,403, 545
that said liquid column, while separate from the a
bath, rises and falls with the high level side of
the bath‘, the high level compartment being ar
'7. The combination of claim 4 wherein the
drainage means comprises: means forming an
over?ow chamber within the high level compart
ment, the over?ow chamber being separated from
ranged to over?ow when the high level side of the
bath tends to rise above ‘the predetermined level;
drainage means for draining the over?ow; and
the liquid column in said compartment by a parti
tion forming an over?ow weir and the air space
make-up means for supplying make-up liquid to
of the compartment above the column and the
the bath to raise its high‘ level when such level
over?ow chamber being sealed except for its com
tends to fall below the predetermined value.
munieation with the air outlet chamber; and
5. The combination of claim 4 wherein: the 10 means providing a liquid sealed drainage outlet
make-up means is arranged to supply make-up
liquid directly to said liquid column.
for the over?ow chamber.
'
8. The combination of claim'4 wherein: means
6. The combination of claim 4 wherein: the
are provided to form a screen chamber which is
make-up means is arranged to supply, during
interposed between the bath and the high level
the operation of said arrester, a continuous 15 compartment and arranged to communicate at
stream of make-up liquid directly to said liquid
its upper end with the atmosphere and, adjacent
column; and means are provided operatively to
its lower end, with both the bath‘ and the high
connect and disconnect said make-up means at
level compartment.
the beginning and end of each‘ operative period
ARTHUR NUTTING.
of said arrester.
20
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