Note: Descriptions are shown in the official language in which they were submitted.
1039776
This invention relates to a sys~em for ~neumat-
ically transferring a batch of particulate material from a
- first vessel to a remote location employing a vacuum-pressure
concept.
"Vacuum-pressure" transfer of particulate material
as used in the art generally refers to the development of a
`~ vacuum in a receiving vessel to induce the flow of particu-
late material into such vessel from a storage or other vessel.
Thereafter, the receiving vessel is nressurized to force the
particulate material out of the receiving vessel to a remote
location. U. S. Patent No~ 27~034 to Smith discloses an
early Yacuum-pressure transfer system. ~;~
The existing vacuum-pressure transfer systems are
limited in various ways. Some require reversible blowers;
others require separated suction and blower means. Certain
o the prior art systems are highly dependent upon the natural
flow characteristics of the particulate material hence are
~i limited as to the time in wl~ich a desired transfer can be made.
, . . . .
Con$equently there has been a persistant need in the art for -
an efficient and economical system for transferring batches
~ of particulate material between separated locations.
:, The present invention res.ides in a system for
;~ pneumatically transferring particulate material in batches
from a first location to a second and remote location, there
~ being provided a first vessel for containing a quantity of
J` the particulate material, the first vessel including a sub-
Stantially conical bottom section having its apex directed
. - downwardly and defining an opening therein. A porous ~ember ~ ;
covers the opening and defines a plurality of passageways
the~ethrough. A second vessel is chargeable with and dis-
chargeable of the particulate material and has a top section
and a substantially conical bottom section having its apex
103~776
directed downwardly. A first conduit means connec-ts tne bottom
section of the first vessel with the top section of the second
vessel, and the first conduit directs the flow of pneumatically
entrained particulate material therethrough from the first
vessel to the second vessel. First valve means is interposed
in the first conduit for regulating the flow of particulate
material through the first conduit means, and filter means is
~ounted on and in fluid communication with the top section of
the second vessel and substantially prohibiting the movement
of the particulate material therepast. There is provided gas
pump means having an input side and an output side with second
conduit means connecting the~input side of the pump means in
. ,
fluid communication with the filter means and including a por-
tion connecting the input side of the pump means in fluid
communication with ambient atmosphere. Second valve means is
interposed in the second conduit means for regulating the flow -
` of fluid between the input side of the pump means and the filter
j4~ ::
I means. Third valve means is interposed in the second conduit ~ -
~1 means at a location between the input side of the pump means
~ 20 and that portion of the second conduit means that opens to
;~ ambient atmosphere for regulating the flow of ambient atmosphere
to the input side of the pump means. Third conduit means
~i cohnect the output 5ide of the pump means in fluid communication
~ with the filter means, and fourth valve means is interposed-~ in the third conduit means for regulating the flow of fluid
through the third conduit means. Fourth conduit means connects
tlle output side of the pump means in fluid communication with
the porous member covering the bottom opening in the first
vessel, and fifth valve means is interposed in the fourth con-
duit means for regulating the flow of fluid through the fourth ~
, .,j .: . ''.
conduit means. Fifth conduit means connects the output side of
the pump means in fluid communication with one slde of the conical
,:
rw/ --
1039776
bottom section of the second vessel adjacen-t the lot~ermost
portion thereof for injecting pressurized fluid from the
output side of the pump means into the bottom section of the
second vessel for entraining particulate material from the
second vessel in the fluid and conveying the same to a location
remote from the second vessel. ~eans controls the functioning
of each of the valve means in a sequence providing cyclical
withdrawal of fluid from the second vessel by the pump means
with concomitant withdrawal of particulate material from the
first vessel into the second vessel with at least a substantial
portion of the withdrawn fluid being conveyed under pressure
through the fourth conduit means and the porous member into
the bottom section of the first vessel, and subsequent flow of
; . .. .
fluid under pressure from the output side of the pump means to
,, the top of the second vessel to provide a volume of pressurized
fluid above the level of particulate material within the second
vessel and flow of fluid under pressure through the fifth conduit
means into the bottom section of the second vessel to entrain
particulate material from the second vessel and transfer the
same out of the second vessel.
It is an object of this invention to provide a
system for pneumatically transferring a batch of particulate
~1 material from a first vessel to a remote depository, employing
;1 24 a single gas pump. It is another object of this invention
':~ ,''i;
`; l ',
" , . .:
, 1
''l .
';', ~, ` .
.~ . .si~
- 2a -
` ; rw/
., ~:, ,.. ,, . , , .. .~ . ..... .... ..
1039776
to provide an automated batch transfer system
for particulate material. Other objects will
become apparent from the following description
including the drawings in which:
FIGURE 1 is a schematic view, in
front elevation, of a system embodying various
features of the invention,
FIGURE 2 is a schematic flow diagram
of the system of FIGURE 1,
FIGURE 3 iS an exploded view of a
filter suitable for use in the system of FIGURE 1,
~ FIGURE 4 is a control circuit diagram
suitable for controlling the operation of the
. ,
system shown in FIGURE 1, and, ;
FIGURE 5 is an alternative switching
circuit diagram for circuitry for introducing
.
a time delay in the control circuit of FIGURE 4. `~
As disclosed herein, the transfer
, system includes a first vessel, e.g. a storage
bin, having a tapered, preferably conical,
, bottom portion, the apex of which is lowermost
''i ,
;~1 and defines an opening, a second vessel, e.g.
a batching vessel, connected to the interior
~1 bottom region of the storage bin by a conduit
`~ 25 suitable for pneumatically conveying particulate
c material from the bottom of the bin into the
top region of the batching vessel when a vacuum
~ is induced in the batching vessel, the batching
i~ vessel also having a downwardly tapered, prefer-
,j 30 ably conical, bottom portion provided with a
pneumatic material transfer device. A single
gas, i.e. air pump having a suction inlet and a
. ~ , .
1039776
blower outlet provides both the vacuum and
pressure required in the operation of the system.
To this end, the blower outlet of the pump is
connected by conduit means to the top region of
the batching vessel, to the material transfer
device and to the bottom portion of the storage
.
bin. The suction inlet of the pump is connected
by conduit means to the top portion of the batching -
vessel and is further selectively open to the
- 10 atmosphere. Filter means is interposed between
the batching vessel and the pump to prevent the -~,
transfer of particulate material to the pump.
Appropriate valves are interposed in the system
to selectively regulate the flow of air within
the system.
In a preferred embodiment, a control
circuit responsive to the quantity of the parti-
culate material in the batching vessel controls
sequencing of the valves to automatically regu-
late the flow of the particulate material.
... . .
~j Referring to FIGVRE 1, the illus-
-;! trated batch transfer system includes a first
-~ vessel, i.e. a storage bin 10, suitable for
receiving and storing particulate material 12.
In one embodiment, the top 14 of the bin 10 is
.~
provided with a removable cover 16 and vented
to the atmosphere through a filter 18. Legs
20, 22, 24 and 26 (24 and 26 not visible) are
~-1 provided for supporting the bin. In a preferred
~3
, 30 embodiment, the bin 10 includes a bottom section
~''t;.' '~
28 that is tapered downwardly, such section pre- -
~ ferably being substantially conical and truncated ~
: ,, ~ :' '
1039776
to define a bottom opening 30 in the bin. This
bottom opening is fitted with a porous plate 32
having its upper face 34 exposed to the interior
of the bin and its opposite and bottom face 36
exposed to a plenum 38 defined by a housing 40
~` to which there is connected a conduit 42 suitable
for introducing pressurized air into the plenum
~ 38, hence through the poxous plate 32 in a multi-
- plicity of streams to the interior of the bin 10 -
as will appear more fully hereinafter.
Particulate material is transferred
.:
in batch quantities from the storage bin 10 to
a second vessel, e.g. a batching vessel 44. -
:.; .
The illustrated batching vessel 44 includes a
downwardly tapered bottom section 46, preferably
conical in geometry with the apex 47 thereof
being truncated, a central cylindrical section
48, and an upwardly tapered top section 50 that
defines a cover 52 having a generally centrally
?~ 20 located opening 54. Legs 56 and 58, and 60 and
i;i 62 (not visible) are secured to the wall of the
central section 48 for supporting the vessel. A
conduit 53 suitable to convey particulate material
' entrained in air connects the top section 50 of
j 25 the batching vessel to a location within and
.~
~ adjacent the bottom of the bin 10. A valve 55 ;
.,.~J ~ .
interposed within the conduit 53 serves to regu-
late the flow of material through this conduit.
The cover 50 in the illustrated
batching vessel 44 is provided with a filter
~, assembly 64 comprising annular base section 66 ~
'~; secured to the cover 50 about the circumference ~;
, ~'" " ~
.,~ :.:.
~ 5
` 10397~6
of the opening 54. The upper edge 68 of the base :
. section 66 is provided with an annular flange 70 ~:
having spaced apart holes 72 through the thick- :
.- ness thereof and is adapted to receive a like :-
annular flange 74 on the bottom edge 76 of a
generally cylindrical housing 78 whose top end : ,
80 is closed so that the housing 78 and base
section 66 collectively define a filter chamber ~;
:~ 82. :~ ;
: 10 A primary filter sub-assembly 83 is
provided within the filter chamber as by inter-
posing between the flanges 70 and 74, a sub- :
assembly comprising at least one filter fabric :
sheet 84 sandwiched between two screen discs 86 :.
!, .
~ 15 and 88 whose perimetral margins are overlaid by -.-: ~
. ,,;~: , . .
annular seals 90 and 92 and clamped between the : ~.
~ annular flanges 74 and 70 of the housing 78 and
;~ base 66, respectively, as by bolts 94 extending
through registered openings in the flanges.
In the illustrated embodiment, a
~:~ secondary filter sub-assembly 96 is provided
within the filter chamber 82 and includes a
manifold 98 mounted at one of its ends 100 in
~ the wall 102 of the housing 78. This manifold
.~ 25 98 extends in cantilevered fashion into the
interior of the filter chamber 82 and above the
:~ primary filter 83. The manifold is provided : .
. ~
with a plurality of porous caps 104 whose
~ respective open ends 106 are threadably mounted
;~ 30 in appropriately threaded lugs 108 provided at
~ spaced apart locations along the length of the :
:~. manifold so that the interior of the manifold
.~ -6
~ , '
~L039776 ; -is in fluid communication wi~h the interior of
the filter chamber. A conduit 110 is attached
to that end 100 of the manifold which is mounted
in the housing wall 102 so that there is fluid
communication between the conduit 110 and the
interior of the manifold 98.
In order to discharge particulate
material from the batching vessel 44, an inlet -
conduit 112 is connected to one side of the wall
114 of the conical bottom section 46 so that
pressurized fluid can be injected into the lower-
most interior portion of this bottom section 46
i. .
by way of the conduit 112. Diametrically oppo-
~ site the location of the inlet conduit 112, there ~
... . . ' . . :.
. 15 is connected to the vessel wall 114 a discharge
, conduit 116 suitable to convey pneumatically
~, entrained particulate material from the lower-
most region of the bottom section 46 to a desired
.,
~ remote location. A valve 118 interposed in the
'','',J, 20 discharge conduit 116 serves in regulating the
flow of gas and particulate material through this
conduit. Desirably, the lower end of the batching
vessel 44 is truncated to eliminate any substan-
tial portion of the vessel below the position of
entry of the conduit 112 into the vessel so that
each discharge operation fully evacuates the
~;~j vessel 44. A further suitable discharge connec- ~ ;~
tion is one of the type shown in FIGURE 4 of
U. S. Patent No. 3,671,079 to W~ D. Huffaker.
The illustrated system anticipa~es
alternately evacuating and pressurizing the batching
` ~ vessel 44 for purposes of accumulating a
',~. ''J
, ~, . .
i~ ', ~': -'
--~ :
~ ;
1039776 -
batch of particulate material in the vessel by ~- -
means of a vacuum transfer and thereafter dis-. :
charging the batch with the aid of pressurization :
::: of the vessel. In the present disclosure, evacu- ::
~' 5ation of the batching vessel and at least initial :~
~ pressurization of the vessel is accomplished in
`~ part by a single gas pump 120 whose input side : ~
122 is connected through the filter assembly 64 : ~:
to the interior of the batching vessel. In the :~ .:
.10 illustrated embodiment, this connection is by
.~.. : . . .: .
`~ means of a conduit 124 and further conduit 110
connected to the end 100 of the manifold 98 of
~1 the filter sub-assembly 96 provided atop the : -
batching vessel 44. The output side 128 of the
pump 120 is also connected to the end 100 of the
manifold 98 as by a conduit 130 and the conduit
110. Valve means 132 interposed in the conduit
` ~ 124 and valve means 134 interposed in the conduit
: 130 function to regulate the flow of air through
. : 20 each conduit. The input side of the pump 120 .
::
: may be opened to atmosphere by means of a valve
136 connected by a conduit 138 into the conduit .
:~ 124. Accordingly/ by selective control of the : .
, ~ flow of air in the conduits 124, 130 and 126,
the single gas pump 120 serves both to evacuate .
~:~ . '.`
. ~ the vessel 44 and to aid in pressurization of
the vessel through the filter assembly 64. It
~¦; will be recognized that equivalent connection :
: : and regulation of the gas flow between the pump :::~
120 and the filter assembly is accomplished by
~, the use of a 3-way valve disposed in conduit 124 :
in lieu of the valve 136 and the conduit 138.
- 8 .
: .~ - .
~- . . .
1039776 ~:
Similarly, one skilled in the art, given the
present disclosure will recognize equivalent
alternative arrangements of the several conduits
and valves to achieve equivalent functioning of
the system. For example, the conduits 124 and
130 could be combined with appropriate and
relatively slight changes in the illustrated
control means. -
- Referring to FIGURE l/ the output
- 10 side 128 of the pump 120 is further connected
by the conduit 112 whose end 142 is connected
in fluid communication with the bottom section
46 of the batching vessel 44. A valve 144
; interposed in the conduit 112 functions to
regulate the flow of air from the pump to the
batching vessel for discharging particulate
material from the vessel and pressurization of
-~ the vessel as will be further described herein-
~ after.
:,
j 20 Further, the output side 128 of the
;l pump 120 is connected by a conduit 146 to the
plenum 38 at the bottom of the storage bin 10.
By means of a valve 148 interposed in the conduit
146, during the transfer of particulate material
1 25 from the bin to the batching vessel, air is
supplied from the output side of the pump 120 to
' provide at least partial fluidization of the
.j
~ particulate material within the bin 10 and thereby
-~ enhance the ~low of particulate material to the
] 30 batching vessel 44. ~ ~
¦ One or more of the valves 132, 134, --
136, 144, 148, 55 and 118 may be manually operable
''~' ." .:.
9-
.
, ~ ' - ..
1039776
between their open and closed positions. Preferably, ~;
each of these valves is of a type which can be
operated from a remote location. This may be
achieved employing conventional hydraulically
operable valves whose operation is controlled
through suitable electrical circuitry means.
' In an operational cycle, the disclosed
system includes evacuation of the batching vessel
44 to develop a low pressure, e.g. a vacuum,
therein relative ~to the pressure in the storage
bin 10, conveying particulate material from the
' bin to the batching vessel while introducing
.. , ~
~' pressurized air to the bottom of the storage ' '
' vessel to aid in entrainment and flow of the
''~ 15 particulate material to the batching vessel,
~i stopping the flow of particulate material to the
batching vessel, pressurizing the batching ves'sel
with the particulate material therein, introducing
pressurized air to the bottom section of the
batching vessel to entrain particulate material
'~ and convey it from the batching vessel through
the discharge conduit to a remote location and
to aid in pressurizing the batahing vessel while
at least partially fluidizing the particulate
'~i' 25 material as air flows from the bottom of the
vessel to the region within the vessel above the
- level of particulate material.
' In operation, the disclosed system may
function in a continuously cycling mode, i.e.
the batching vesseI may be charged and discharged
.. ~ ;
1f without a significant time'lag betwee'n the phases'
within a cycle or between successive cycles.
, ~ ~
;: j : .
,. . ,1, --10--
. ~, .
1039776 :
Alternatively, the system may be provided with
dwell time between charging and discharging or -
between discharging and charging as is compatible
or desired in a given application of the system.
For example, in a bakery, it may be desirable
.: :
to continuously cycle the system with successive
batches being conveyed to individual ones of a
member of dough mixing vessels. In a cement
plant, however, it may be required that there be - -
a waiting time following charging of the batching
:. :
vessel before it is discharged. In the continuous
cycling operation, preferably each of the several
valves in the system is automatically opened or ;~
closed so that minimum operator attention need
3 15 be given to the system while it is functioning.
Automatic regulation of the operation of the
system with built-in dwell time or times is ob-
tained such as through the use of time reIays
in an electrical control circuit.
In either event, in an operation of
the illustrated system, commencing with parti-
~ culate material 12 in the storage bi.n 10 and the
;~ batching vessel 44 discharged, the pump 120 is ~
turned on and valve 132 is opened to cause air ~;
to be withdrawn from the interior of the batching
vessel through the input side of the pump 120
and reduce the pressure therein relative to the
pressure within the storage bin. Valve 136 is
~: closed during this operation. Val~e 55 is opened
,~ 30 to start the flow of particulate material from
the bin lnto the batching vesseI. Valve 148 is
~-~ opened to admit pressurized air from the output
.- . - - , .
. .. ~ ~ ~ , . :, .
: : . -
` . -11- . ~ -.
~039776 ~
side 128 of the pump 120 to the plenum 38, thence
through the porous plate 32 in a multiplicity of
' flow streams to the interior of the bin to at
least partially fluidize the particulate material
~' 5 in the bin and enhance its entrainment and trans-
fer through the conduit 53 into the batching
~ vessel. When the desired quantity of particulate
; material has been transferred into the batching
~"~ vessel, valves 132, 148 and 55 are closed, stopping '
;, :
; 10 the transfer of material into the batching vessel. '~
'' If desired, at this point in the cycle a dwell '
'' time is convèniently provided. -
~; To discharge the batching ves'sel, the
'~ pump is in the "on" mode and valve 136 is opened ~ '
to open the input side 122 of the pump to ambient
:,:.:, , . :.,,:
~ atmosphere. Valve 134 is opened to admit pres~
;'~ surized air from the output side 128 of the pump ;~
~ through'the filter assembly 64 into the batchi'ng "
:^ . . .
~ vessel to at least substantially increase the
;~ ~' 20 pressure in the region of the batching vessel
`~ above the level of the particulate material
~ therein. 'Valves 118 and 144 are opened so that
'i pres9urized air from the output side'of the pump
is introduced through the conduit 112 into the
lowermost portion of the bottom conical section '
`" of the batching vessel in a direction toward the
discharge'conduit 116 and particulate material
is entrained by the flowing air and conveyed out '
of the batching vessel through the discharge
conduit 116. Simultaneously, a portion of the
air introduced into the batching vessel through ~ ;
the input conduit 112 flows upwardly through the
. , ~ . . .
-12-
-
1039776
particulate material in the batching vessel to
at least partially fluidize the particulate
material and to aid in pressurizing the region
within the batching vessel above the changing
level of the particulate material therein.
In one embodiment, the quantity of
particulate material transferred into the batching
vessel during the charging thereof is determined
by weight. This is accomplished by mounting the ~;
batching vessel on a set of scales 160 whose
balance arm 161 or other member (FIGURE 4) serves
to close a switch 162 in an electrical control
circuit that functions to regulate the operation
of the system. To this end, the conduits 53, 124
and 130 are each provided with flexible couplings,
157, 158 and 159, respectively, to allow for
vertical movement of the vessel 44. Various
equivalent modifications of such arrangement will
be apparent, given the present disclosure.
With reference to FIGURE 1, 2 and 4,
in one embodiment of the disclosed system, valves
136, 148, 55, 118 and 144 are each normally-
closed two-way valves and valves 132 and 134 are
normally-open two~way valves, each of whose
respective opening or closing is accomplished
by solenoids 146 (opens valves 136 and closes
valve 132), 166 (opens valves 118 and 144), 168
(closes valves 134 and opens valve 148) and 170
(opens valve 55). These valves suitably are
hydraulically operated and the hydraulic flow
thereto is regulated by the solenoids acting
through appropriate other valves as is known -~
'' ' ~
1039776
in the art. Alternatively, the several valves
may be operated directly by the solenoids. The
solenoids 168 and 170 are connected with a first
thermal delay relay 172 and a lamp 174 in a charging
circuit "A" that is energized by an appropriate
signal from a switching circuit 176. Solenoids
164 and 166 are connected with a second thermal
delay relay 178 and a lamp 180 in a discharging
circuit "B" that also is energized by an appro-
priate signal from the switching circuit 176 whose
function is to select which, if either, of cir-
cuits "A" and "B" is energized at a given time.
i This circuit 176 suitably comprises the switch
162 and a lead 175 connecting one terminal 177
of the switch 162 to circuit "A" and a lead 181
connecting the other terminal 179 to circuit "B",
thereby selectively energizing these circuits
by connecting each at the appropriate time to
the lead 184 from the electrical power source.
A main switch 182, when closed,
supplies power to the pump 120 and to the
sWitching circuit 176 through leads 184 and
186, one of which has interposed therein a
a manual switch 190 that serves at a "start" - ;
"stop" switch for the overall operation of the
~ control circuit.
;~ Upon the closing of switch 162 by
reason of the weight of particulate material in
the batching vessel being of the required amount
~; 30 to activate the scales 160 to close switch 162,
, the switching circuit 176 sends a signal to
circuit "A", activating only the thermal delay
::
~:
- -14-
~ '
. ,., . .. . . ... ., . , , . ~
1039776
relay 172. After a brief delay, sufficient to
ensure that the discharging circuit "B" has been
deenergized and valves 136, 118 and 144 have
closed and valve 132 has opened, 168 and 170 are
substantially simultaneously energized to open
valve 55, hence open the conduit 53 leading be-
tween the bin 10 and the batching vessel 44 for
the flow of particulate material therethrough,
to open valve 148 and commence the flow of air ^~ -
into the bottom of the bin 10, and to close valve
134 to stop the flow of pressurized air into the ;~
top of the batching vessel. At this point in
time, circuit "B", the discharging circuit, is -~
not energized so that valves 136, 118 and 144
x 15 are closed, thereby closing off the input side
of the pump from ambient atmosphere, and closing
off the flow of air into the bottom of the
. i . ,
~',! batching vessel and through the discharge con- - !'
duit 116. During the time the solenoids 168
and 170 are energized and the batching vessel
is being charged, the lamp 174 is lighted.
~ When the weight of particulate material
4~ in the batching vessel reaches a predetermined
~l amount, the scales 160 are satisfied and the
¦25 switch 162 opens. This results in deenergizing
of the charging circuit "A" and energizing the
discharging circuit "B". Immediately upon ener-
gization of this circuit "B", 164 is activated
to close valve 132 and stop the suction of air
~ , :.:,
from the batching vessel and to open valve 136
to ambient a*mosphere. After a time delay suffi- -
, cient for valves 144 and 55 to close and valve
:~ . . "'~: ' '
i -15-
'x ''' ''' . ''' ' ' ''' ''"' ~; ' `'. ~ ; "''; '
~039776
134 to open ~ollowing deenergization of charging
circuit "A", and to stop the transfer of material
into the batching vessel, the relay 178 closes
to activate solenoid 166 for opening valves 118
and 144 to commence the discharge of particulate
material out of the batching vessel. Lamp 180
is energized and remains lighted during the times
the solenoid 166 is activated. Notably, during
the time interval between initial energization
of the discharge circuit "s'! and the opening of
valves 118 and 144 to commence the discharge,
valve 134 is open to admit pressurized air into
the top of the batching vessel to commence the
build-up of pressure above the level of the parti~
culate material in the vessel for assisting in
the discharging of the particulate material out
of the vessel and to provide a flow of air in a
"reverse" direction through the filters.
A further suitable switching circuit
191 that does not require scales, but rather pro-
vides a time-dependent operational control over
the operation of the system, is shown in FIGURE 5
and includes a timing motor 192 connected to the
leads 184 and 186. This motor 192 serves to opexate
a switch 194 of a type having three positions,
namely a first position 196 which connects the
electrical power source to circuit "B", a second -
position 198 which is neutral, and a third position
. .
~ 200 which connects the electrical power to cir-
.
cuit "A". Through selection of the time that the
switch remains in the neutral second position 198,
there is provided a time delay between the charging
. .
.
-16-
~ ~ ,''~''."
- 1039776
and discharging of particulate material in and
from the batching vessel 44. Selection of the
time operation of the timing motor provides for
timed charging of the batching vessel and/or timed -
discharging of the vessel.
In FIGURE 6 there is illustrated a -
means for providing a time delay between charging
and discharging of the batching vessel, employing
a modification of the control circuit of FIGURE 4.
This means includes a thermal delay relay 201
and a switch 202 interposed in the lead 181 be-
tween the switching circuit 176 and circuit "B"
so that by manual operation of the switch 202,
there is interjected a time delay between the
time of deenergization of circuit "A" and the
` time of energization of circuit "B". Other equi-
valent modifications of the control circuitry
will be apparent to one skilled in the art when
given a particular set of desired operation
parameters.
Notably, in the illustrated apparatus
the filter assembly is mounted directly onto the
top of the batching vessel. This has been found
useful in minimizing maintenance of the filter
assembly in that when the batching vessel has ~ -
been charged and pressurization of the batching
vessel commences, the "reverse" flow of air through
.~ i ~ ,.
the filters cleans the filters, particularly the
primary filter sub-assembly 83, by dislodging
therefrom the particulate material collected on
the filters during the withdrawal of air during
.
the charging operation. This dislodged material ~ ;
either falls or is carried by the air directly
. ~ , .
1039776
into the batching vessel thereby not requiring
frequent dismantling of the filter assembly or
other work normally associated with filter main-
tenance and/or recovery of material from the
filter.
While a preferred embodiment of the
present invention has been illustrated and des-
cribed, it will be obvious to those skilled in
the art that changes and modifications may be
made therein without departing from the invention
in its broader aspects. Various features of the
invention are set forth in the following claims.
; .", :
, .' :'
.
'`'
. ' . ' .
: '
.:
', ',, :,
~: :
::
.::..
~ -18- ~
- " '
