Method and apparatus for bottom loading a pneumatic transport pressure vessel

The pneumatic conveying system according to the present invention includes a pneumatic transport pressure vessel having funnel-shaped sides and a closed domed top. The pneumatic transport presure vessel has a single inlet/outlet opening at the bottom of the funnel-shaped sides. The pneumatic transport pressure vessel is connected to a switch valve having a pipe section movable between first and second positions. In the first position, the switch valve connects the pneumatic transport pressure vessel to a positive displacement mechanical feeder to bottom load material from a storage hopper through the switch valve into the pneumatic transport pressure vessel. In the second position, the pipe section of the switch valve connects the pneumatic transport pressure vessel to discharge piping for conveying the material pneumatically to a desired discharge location.

FIELD OF THE INVENTION 
This invention relates to pneumatic conveyance of materials, and more 
particularly, to a method and apparatus for bottom loading a pneumatic 
transport pressure vessel. 
BACKGROUND OF THE INVENTION 
It is generally known in the art to use a top loading gravity flow 
apparatus for charging bulk materials to a pneumatic transport pressure 
vessel. Typically, these conventional top loading gravity flow devices 
require high headroom and a large amount of horizontal plant floor area. 
In many existing facilities, the required amount of headroom and plant 
floor space is limited and the conventional gravity flow top loading 
apparatus is not economical. In the conventional system, material chips, 
such as wet or dry metal chips (with or without coolant fluid), are 
conveyed to a vibrating storage hopper mounted above the transport 
pressure vessel which stores material for subsequent gravity feeding to 
the pneumatic transport pressure vessel. An inclined screw conveyor 
elevates the chip materials above the pneumatic transport pressure vessel 
for top loading by gravity feed from the discharge of the vibrating 
storage hopper. The top of the pneumatic transport pressure vessel is 
sealed by means of a dual valve configuration allowing pressurization of 
the pneumatic transport pressure vessel for conveying. 
It is generally known in the art to use switch valves for switching the 
connection from the discharge of the pneumatic transport pressure vessel 
between two alternate discharge pipes leading to different discharge 
collection points. Many of these switch valves use an inflatable pneumatic 
seal which is unacceptable for use in conveying metal chips, since the 
metal chips readily puncture the inflatable pneumatic seal. In addition, 
many of these switch valves are limited in use to applications where the 
switch valve is clear or empty of material when actuated or switched, and 
are typically used only for switching between two alternate discharge 
piping outlets. 
SUMMARY OF THE INVENTION 
The present invention includes a horizontally disposed screw feeder which 
has a material inlet at one end and discharges through a switch valve in a 
first position into the interior of a pneumatic transport pressure vessel. 
After the pneumatic transport pressure vessel has been filled to the 
desired level, the screw feeder stops and the switch valve is actuated to 
connect the pneumatic transport pressure vessel to the discharge pipe 
outlet. After the switch valve has connected the pressure vessel to the 
discharge pipe outlet, the pneumatic transport pressure vessel is 
pressurized forcing the chip materials through the switch valve and into 
the discharge piping. Upon completing the discharge of the chip materials, 
the switch valve is again actuated to return to the first position 
connecting the discharge of the screw feeder to the pneumatic transport 
pressure vessel for subsequent loading, and the above described cycle is 
repeated. The bottom loading configuration for the apparatus is desirable 
in that it eliminates the high headroom requirements necessary with 
gravity loading and also reduces the cost of the system by reducing the 
length of the screw feeder equipment and by eliminating the dual valve 
seal previously required at the top of the pneumatic transport pressure 
vessel to obtain the necessary seal required for pressurizing the 
pneumatic transport pressure vessel for pneumatic conveying or 
transporting. 
The switch valve assembly according the present invention replaces the 
inflatable pneumatic seals previously used with a plastic ring-shaped 
piston seal which is slidably disposed in an annular slot and sealed with 
a rubber O-ring seal on either side. An inlet allows pressurized air to 
engage one side of the plastic ring-shaped piston seal which forces the 
plastic ring outwardly into engagement with the side wall through which 
the pipe communicates with the flanged inlets and outlets. Air is released 
from the piston chamber to disengage the plastic seal prior to activation 
of the switch valve to move the bias cut pipe connection from the first 
position to the second position. The plastic ring-shaped piston seal 
allows pneumatic conveying of metal chips, since the plastic ring-shaped 
piston seal is resistant to damage from the metal chips. In addition, the 
switch valve operating mechanism and actuator have been modified to allow 
the present switch valve to be switched or moved from one position to the 
other position when full of material to be conveyed. Furthermore the 
present switch valve has been further modified to include means for 
closing the unused pipe opening when the switch valve pipe is 
communicating with the other pipe opening. 
Other objects and features of the invention will become apparent by 
reference to the following specification and to the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention of an apparatus for bottom loading a pneumatic 
transport pressure vessel includes a horizontally disposed screw feeder 10 
having a material inlet 12 at one end and a material discharge outlet 14 
at another end. The screw feeder 10 discharges through a switch valve 16. 
The switch valve 16 includes three pipe connections designated 18, 20 and 
22. A movable bias cut pipe section 24 is disposed within the switch valve 
16. The bais cut pipe section 24 is movable between a first position 24a 
and a second position 24b by fluid pressure actuated motor means 26. In 
the first position 24a, the pipe section 24 is in communication with the 
pipe connections designated 18 and 20. The pipe connection 18 connects the 
switch valve 18 to the horizontally disposed screw feeder 10, while the 
pipe connection 20 connects the switch valve 16 to the bottom of the 
pneumatic transport vessel 28. In the second position 24b, the pipe 
section 24 is in communication with the pipe connections 20 and 22. Pipe 
connection 22 connects the pneumatic transport pressure vessel 28 through 
the pipe section 24 to discharge piping 30 for pneumatic conveying or 
transporting of the material to a desired location. The fluid pressure 
actuator means 26 is controlled by valve means 32 for switching 
pressurized fluid between first and second fluid chambers, wherein the 
fluid pressure actuated means 26 includes an operatively moveable piston 
reciprocally disposed within a cylinder for movement between first and 
second end limits of movement, thereby moving the pipe section 24 of the 
switch valve 16 between the first and second positions 24a and 24b, 
respectively. 
The pneumatic transport pressure vessel 28 includes an inverted truncated 
conical vessel side wall with a domed top, and a reducing elbow pipe 
connection connecting the pneumatic transport pressure vessel 28 to the 
pipe connection 20 of the switch valve 16. The reducing elbow connection 
36 acts as the single inlet/outlet for material to be transported into and 
out of the pneumatic transport pressure vessel 28. Material level sensing 
means 34 is provided within the pneumatic transport pressure vessel 28 for 
indicating that material has reached a desired level within the pneumatic 
transport pressure vessel 28 during loading. The sensing means 34 is 
connected through appropriate circuitry to stop the screw feeder 10 upon 
sensing that the material level within the vessel 28 is at the desired 
level. The control valve means 32 is then activated to operate the fluid 
pressure actuated means 26, thereby moving the pipe section 24 from the 
first position 24a to the second position 24b. Upon completion of the 
movement of the pipe section 24 to the second position 24b, second control 
valve means are actuated to introduce pressurized fluid, such as 
compressed air, into the vessel 28 adjacent the top. The compressed air 
enters the vessel 28 above the material level within the vessel 28. 
Compressed air enters the funnel shaped transport pressure vessel 28 to 
partially fluidize the static load of material contained therein. The air 
pressure then squeezes the load of material into a cylinder entering the 
conveying pipeline for transportation to the desired discharge point. 
In the present invention, an air header pipe valve assembly controls the 
compressed air supply to the funnel-shaped pressure vessel which, when 
pressurized, initiates the material conveying cycle. The transition elbow 
36 attached to the bottom of the vessel 28 completes the reforming of the 
partially fluidized wet or dry materials into a cylinder for pneumatic 
conveying through the pipeline. The funnelization of material into a 
cylinder during partial fluidization permits the material to be reshaped 
for delivery to and through four-inch diameter pipelines. The cylinder of 
material is accelerated by the compressed air entering the pressure vessel 
which provides the propelling force to complete the conveying distance 
through the pipeline to the discharge point. As soon as the conveying 
distance is accomplished, the air pressure drops to near atmospheric, and 
the compressed air supply is terminated by the second control valve means 
38. 
The pneumatic conveying system is then ready for the next batch of material 
to be loaded. The control valve means 32 is then activated to operate 
fluid pressure actuated means 26 to move the pipe section 24 of the switch 
valve 16 from the second position 24b to the first position 24a. After 
reaching the first position 24a, the screw feeder 10 is activated to load 
the next batch of material into the pneumatic transport pressure vessel 
28. 
Referring now to FIGS. 3 and 4, the switch valve 16 used in the present 
invention is shown in greater detail. FIG. 3 shows a plan view of the 
switch valve 16 with a door removed for clarity. FIG. 4 is a sectional 
view of the switch valve 16 taken as shown in FIG. 3 with the pipe section 
24 shown rotated between the first and second positions. The switch valve 
16 includes the pipe section 24 having first and second sealing ring 
housings 40 and 42, respectively, at opposite ends thereof. A plurality of 
cam followers 44 are disposed around the first sealing ring housing 40 
adjacent the end of the switch valve 16 where the pipe section 24 connects 
to the pipe connection 20. The cam followers 44 maintain the first sealing 
ring housing 40 in position while allowing rotary movement of the pipe 
section 24 within the switch valve housing between the first and second 
positions 24a and 24b, respectively. 
The second sealing ring housing 42 is connected to a pivot shaft 46 passing 
through a wall of the enclosure housing the pipe section 24 adjacent the 
pipe connections 18 and 20, respectively. The pivot shaft 46 is operably 
connected to the fluid pressure actuator means 26 through pivot linkage 
arm 48. As the fluid pressure actuated means 26 is reciprocated between 
the first and second end limits of movement, the reciprocal motion is 
transformed into rotary motion through the linkage arm, thereby driving 
the pivot shaft 46 and second sealing ring housing 42 in pivotal movement 
about the longitudinal axis of the pivot shaft 46. The rotary motion of 
the pivot shaft 46 and second sealing ring housing 42 causes the pipe 
section 24 to move between the first and second positions 24a and 24b to 
switch to the desired pipe connection. 
Each sealing ring housing is connected to the pipe section 24 and includes 
an annular groove formed in a face of the sealing ring housing facing 
outwardly toward the immediately adjacent wall of the enclosure of the 
switch valve 16. A sealing ring 50, preferably made of a plastic material, 
is slidably disposed within each annular groove. The sealing ring 50 is 
sealed with an inner diameter O-ring seal 52 and an outer diameter O-ring 
seal 54. A chamber is formed between the sealing ring housing and the 
sealing ring by means of the inner and outer diameter O-ring seals 52 and 
54, respectively. Pressurized fluid, such as compressed air, is in fluid 
communication with the chamber through pipe connection 56 for operatively 
engaging the sealing ring against the enclosure wall when the pipe section 
24 has reached the first or second position 24a and 24b. The sealing ring 
50 is preferably selected from a plastic material which is resistant to 
the material being transported, such as abrasive metal chips, while 
allowing sealing engagement of the plastic seal ring against the wall of 
the enclosure. Control valve means 60 are provided to pressurize and 
depressurize the chamber which seats the seal ring against the wall of the 
enclosure. Preferably, the chamber is depressurized before moving the pipe 
section 24 between the first and second positions. 
In operation, the present pneumatic conveying system begins a cycle with 
the pipe section 24 in the first position 24a and with sealing rings 50 
engaged against the wall of the enclosure by applying pressurized fluid 
through valve control means 60 and pipe connection 56. The screw feeder 10 
is operated to draw material from a storage hopper (not shown) through 
material inlet 12 and is discharged through discharge outlet 14. The 
material discharged passes through pipe connection 18 of switch valve 16, 
through pipe section 24 and out through pipe connection 20. The material 
is then forced by continued operation of the screw feeder 10 through 
transition elbow 36 and into the pneumatic transport pressure vessel 28. 
After a sufficient quantity of material has been transferred by the screw 
feeder 10 into the pneumatic transport pressure vessel 28, the sensing 
means 34 is activated by the level of material. On activation of the 
sensing means 34, the screw feeder 10 is deactivated, control valve means 
60 depressurizes the seal rings 50, control valve means 32 operates fluid 
pressure actuated means 26 to switch the pipe section 24 from the first 
position 24a to the second position 24b, control valve means 60 
repressurizes sealing rings 50 and second control valve means 38 opens to 
partially fluidize the static load of material contained within the 
pneumatic transport pressure vessel 28. The air pressure then squeezes the 
load of material, such as metal chips, into a cylinder as it passes out of 
the pneumatic transport pressure vessel 28 through transition elbow 36, 
pipe connection 20, pipe section 24, pipe connection 22 and thereafter 
entering the discharge piping 30 for transporting to the terminal point 
for final discharge into a receiving hopper (not shown). After discharge, 
the air pressure within the pneumatic transport pressure vessel 28 drops 
to near atmospheric and the second control valve means 38 is deactivated 
by control logic pressure sensor P. The control valve means 60 then 
depressurizes the seal rings 50 and the control valve means 32 is 
activated to operate the fluid pressure actuated means 26 to move the pipe 
section 24 from the second position 24b to the first position 24a. On 
reaching the first position 24a, the control valve means 60 repressurizes 
the chamber within the sealing ring housings to drive the sealing rings in 
sealing engagement against the wall of the switch valve enclosure. The 
screw feeder 10 is then activated to load the pneumatic transport pressure 
vessel with another batch of material. 
While one embodiment of the invention has been described in detail, it will 
be apparent to those skilled in the art that the disclosed embodiment may 
be modified. Therefore, the foregoing description is to be considered 
exemplary, rather than limiting, and the true scope of the invention is 
that defined in the following claims.