VINCENT VP-16 Handbuch
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Contents
Overview 5
Safety 5
Rigging 6
Installation 6
Press Components
A/B/C/D-plates
Air Regulator / Filter and Cone Positioning Valve
Discharge Cone 8
Cone Bushings 10
Screw / Screw Configurations 11
Wing Feeders 12
Notches 12
Resistor Teeth 13
Screens 13
Cord Cutter and Stripper Pins 15
Motor / Gearbox 15
A-plate Shaft Seal 16
Variable Frequency Drives (VFDs) 16
Vincent Cone Timers (VCTs) 1
Start up 1
Screw Speed (RPM) 18
Feeding the Press / Pre-Thickeners 18
Building a Plug 19
Additional Hints 19
Vacuum Effect 19
Instruments 20
Stopping the Press 20
Double Pressing 20
Moisture Content 21
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Compression 21
Measuring Throughput 22
Screw Life 22
Pie Cutting 23
Jamming / Plugging 24
Screen Blinding 25
Channeling 25
Purging 26
Bridging 26
Fluid Injection 26
Polymer Usage 2
Press Aid 2
Hydrated Lime, Gypsum, and Alum 28
Cleaning 28
Maintenance 29
Checking Screw to Screen Clearance 29
Screen Removal and Replacement 30
Screw Removal and Replacement 30
Lubrication 32
Maintenance Checklist 33
Nomenclature Drawing 34
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Overview
The Vincent KP Press consists of a screw rotating within a screen housing, a flanged inlet
hopper, and a discharge opening. At the discharge end, the mouth of the screen housing is
closed by a pneumatically actuated cone which moves back and forth on the screw shaft in
proportion to the internal pressure in the screen frame. This motion is opposed by the cone
cylinder thrust, thereby regulating the discharge of solids. An air regulator is provided to adjust
the pressure on the cone. The liquids, which are squeezed from the wet product, escape through
the screen housing and are caught in a built-in pan under the screen.
The screw is driven by a fixed speed electric motor that is C-face mounted to a gearbox. The
gearbox reduces the RPM from the typical 1 50 RPM output of the motor to an appropriate
speed for the application, 5 - 50 RPM. The hollow bore gearbox mounts directly on the screw
shaft and is flange mounted to the machine.
The numbers in the model designation stand for the nominal diameter of the screw in inches.
As the press has been adapted to many different applications, options have been added to the
press. These include interrupted or continuous flighted screws, conical screws where the shaft
increases in diameter, different shape inlet hoppers, different style cones, etc. As a result, not all
the information contained in this manual will apply to your press.
Safety
A screw press, like any screw conveyor, is totally unforgiving. If clothing or a limb gets
caught in a rotating screw, the screw will not stop.
Wear safety glasses around the press.
Avoid loose-fitting jewelry or clothing, including high-visibility safety vests. If vests
are required, the Velcro, tear-away type are recommended.
Always lock out electric and compressed air before working on the press.
Dewatering presses squirt liquid out, particularly if screen covers are removed. If
material is hot, acidic, or caustic, do not remove screen covers while operating.
Wear gloves when performing maintenance.
When removing the tailstock and discharge mechanism, watch for pinch points and
hinged assemblies. Be careful when removing or installing the screw and screen when
they are fed through the C-plate as this is a particular pinch point.
Never stand near a press being suspended during installation.
Provide an E-stop button near the press.
Keep hands out of the press inlet and press cake discharge area.
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Rigging
Be sure to properly support the press when lifting it from the truck. Usually a sling
positioned under the inlet hopper, on the side closest to the gearbox, finds the center of
gravity. On bigger presses, do not lift just one corner of the press, as it is possible for the
frame to deflect, shifting the screw within the press.
Installation
These presses are typically called horizontal screw presses. This doesn't mean that the
presses must be installed exactly level from inlet to discharge. Presses are often installed at
an upward angle. Consult the factory if you need to install the press at an angle above 15° as
an adjustment to the gearbox may be required.
Be careful not to rack the press when tightening the mounting bolts. In the case of large
presses, do not just bolt or weld the press down to a level foundation! Instead, first place the
press where it is to be installed. Next, place shims between the press frame and the steelwork
(or floor, concrete pedestal or foundation) to fill any gap where the press is to be anchored.
Only after shimming (or grouting) should the press be pulled down tight. Doing otherwise
can rack the frame of the press, and this can cause screw-to-screen interference.
A large press must be mounted solidly, preferably to a foundation or structural steel. If a
press draws its full rated horsepower without the press being anchored to the floor, the frame
of the press can twist.
For maintenance, the screw is removed through the cake discharge end of the press. Allow
the space required.
To suit individual conditions, a hollow bore gearbox can be rotated 180o, 90o either way.
Consult the gearbox manual or Vincent factory in these situations as it is likely that the oil
level in the gearbox will have to be adjusted.
Material can be fed into the press many ways. You may need to allow for return feed of
overflow material if more is fed to the press than it can take. When material is piped to a
press in a closed piping system, it is important to have a 2" vent line open to the atmosphere,
along with an overflow return line. The vent is necessary to prevent a siphon effect which
can induce a vacuum in the inlet hopper and reduce press capacity. The return line should
empty above the surface of the return pit. The overflow should fill less than half of the cross
section of the return line.
Spill containment is a consideration which should be considered, because it may be possible
for un-pressed material to purge from the cake discharge of a press.
We recommend that a manual disconnect, for killing power to the motor, be installed close to
the press.
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A variable frequency drive (VFD) programmed for either variable speed or auto-reversing
may be required, depending on the application. If not, the use of a reversing starter switch is
recommended; they cost only a little extra. Such a switch is handy for clearing a jammed
press.
It is possible that, when operating intermittently with very wet material left in the press
between runs, the liquid may loosen the cake plug at the discharge. This might cause the
plug to blow out upon start-up. To minimize this condition, the press can be installed with
the discharge tilted upwards.
Press Components
A/B/C/D-plates
There are four vertical plates making up the frame of the press, called out in the
Nomenclature drawing at the end of this manual. The motor is connected to the gearbox with
a stub shaft protruding toward the press. The stub shaft is connected to the screw with a
coupling. Going into the inlet hopper is the inlet hopper seal assembly attached to the A-
plate. This A-plate forms one wall of the inlet hopper.
The next plate is the B-plate. It forms the downstream wall of the inlet hopper. The screen
starts at the B-plate. There may be a notch (or pair of notches), called a Cord Cutter, in the
B-plate. Also, there may be a bar called Brian's Stripper welded to the B-plate, inside the
inlet hopper; it is designed to kiss the edge of the screw flight as it passes. These two
features prevent long fiber pieces from balling up at the exit of the inlet hopper. See the
“Cord Cutter and Stripper Pins” section ahead.
The next plate, the C-plate, supports the discharge end of the screen. The discharge cone
touches the C-plate when the cone is in the closed position.
The final plate, the D-plate, has the twin air cylinders mounted on it. The screw shaft
terminates at the D-plate via the attached flange bearing.
Air Regulator and Cone-Positioning Valve
To regulate the air pressure of the discharge air cylinder, presses are supplied with an air
pressure regulator along with a Parker 4-way cone positioning valve. These are typically
installed near the cone end of the press. [Until recently FRL (Filter, Regulator, Lubricator)
sets were provided to regulate air pressure. Most air cylinder manufacturers now recommend
against the use of lubricators.]
The Parker valve allows manual selection of the shut, open, or "neutral" position. This valve
connects air supply from the regulator to one end of the air cylinder, while simultaneously
opening the other end to atmosphere. The vent line on the 4-way valve allows air to escape
when pressure is switched from one end of the air cylinder to the other.
Continuous air flow from the Parker vent line indicates a leak inside the air cylinder, or
possibly a faulty 4-way valve.
The neutral position of the Parker valve is used only in testing. If left in the neutral position,
the cone will not move unless it is pushed open by press cake. If, later, the flow of press
cake is diminished, the cone will remain in the position to which it was pushed, and purging
can occur.
Dis harge Cone
The principal adjustment of the press is made with the discharge cone. The cone is the
component at the cake discharge end of the press that acts as a door or stopper plug to restrict
material from leaving the press. The more pressure exerted by the discharge cone, the drier
the cake material will be leaving the press. Also, the motor amps can be expected to increase
with added pressure, and throughput may decrease.
The discharge cone is moved in (actuated) either by an air cylinder or, rarely, by weights.
Typical air cylinder pressures are in the range of 30 to 60 psi. Some materials will press only
in a low range, say 10 to 20 psi. Other materials may press best with a pressure of 60 to 100
psi. Air consumption is minimal in all models, 1 to 2 cfm.
During initial, first-time start up, presses with air cylinder actuators are generally started up
with the discharge cone in the withdrawn position. This will avoid an unnecessary jam.
With the air cylinder models, the discharge cone mechanism can readily be positioned in the
"open" (withdrawn or "out") position.
Note that with many materials it is necessary to start the press with the discharge cone in the
closed position at low air pressure. Thin or soupy materials, like pumped manure or clarifier
underflow, can tend to purge right through the press if the press is operated with the
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discharge cone open [in the withdrawn ("out") position]. However, with materials that are
dry to begin with, such as sawdust or plastic wash tank sludge, it becomes more important to
start with the discharge cone in the open position. This is because these materials may tend
to jam or overload the press. Similarly, high freeness materials, from which the water falls
away freely, will tend to jam in a press. Start the press with the cone open, then close it with
low air pressure initially, when running such materials for the first time.
Most presses are operated 24/ . Once you are through the initial startup, it will be unlikely
that your press should have the cone opened before starting. Most operators rarely open or
shut the cone once it is set. However, it is recommended to cycle the cone in and out once
per shift. This ensures that grease for the bushings is spread across the screw shaft.
As the pressure on the discharge cone is increased, not only will the cake become drier, but
the flow through the press may also be reduced. With very slippery or slimy feed material it
may be possible to apply enough discharge cone pressure to stop the flow altogether.
High discharge cone pressures can result in increased quantities of suspended solids in the
press liquor.
Care must be taken if a press is to be left running at a very low pressure like 10 psi. If some
fiber enters between the cone bushing and the screw shaft, it will take more than that much
pressure to close a cone which has been pushed open by a heavy flow of cake. The result
will be either high moisture content in the cake or, worse, purging.
With some feed materials, the press can be operated with the discharge cone in the
withdrawn position. The screw alone may do enough compressing and dewatering to
produce a cake at the discharge.
It is acceptable to open the discharge cone, in most cases, during normal operating
conditions. This allows inspection, while in operation, of the discharge end of the screw and
screen. This will give the operator a chance to observe operation with minimum dewatering
and maximum throughput. It is also a good technique for purging bad material, i.e. either
jammed or spoiled material, from the press. (Do not try this trick if you are pressing hot or
chemically aggressive materials.)
Where very low air pressure is required for proper operation, it may be practical to put the
cone positioning valve in a neutral position, halfway between open and closed. A press
cannot be left permanently in this condition: keep in mind that a slug of cake will push the
cone open, and it will not re-close on its own afterwards.
An unusual technique is to set the air pressure so that the cone normally stays completely
shut. A timer is used to periodically open the cone. The closed period is determined by the
amount of time required for press cake to accumulate in the press. This type of operation is
used with slippery or slimy press cake that cannot be dewatered to sufficient firmness to
force the cone open. The duration of the "cone open" period is long enough to dump much
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of the press cake that has been formed. Vincent Cone Timer panels are available at a
minimal cost.
Once through start-up, the cone is almost always left in the closed position at whatever air
pressure has been found to be effective. A plug of cake will be left around the cone
whenever the press is turned off; this will normally clear on its own accord on restarting the
press. To prevent a potential jam upon restarting, it is a good idea to open the cone for a few
minutes prior to shutting down the press, after flow to the press has been stopped. Although
there will be solids left in the press, they won't be highly compacted.
There are a few applications where the air cylinder is removed and replaced with a jacking
bolt. This is used if the cone pushes completely closed even with the lowest air pressure. It
results in operating the press with a fixed discharge annulus, or air cylinders with linear
actuators are available.
Cone Bushings
The cone rides on the shaft of the screw. "Cone Sleeve" is the name given to the portion of
the screw on which the cone rides. There are dual bronze or UHMW bushings in the cone to
support and guide it, and to protect the Cone Sleeve journal surface of the screw shaft.
Sometimes the bushings are lubricated with liquid from the material being pressed, such as
the juice from apples or water from pectin peel. Sometimes there is a grease fitting provided
for lubricating the bushings or to minimize leakage of press liquor through the cone
bushings. And sometimes, an AutoLube is included for automated lubrication of the cone
bushing.
Bushing lubrication is extremely important when materials that are dry (like paper mill
screen rejects) are being pressed. By the time such materials reach the discharge of the press,
they do not have enough free moisture left in them to adequately lubricate the cone bushings.
In these applications the operator should, at the start of each shift, pump grease in until it
comes out between the cone bushing and the screw shaft. Then he should open and shut the
cone three times in order to spread the grease.
Rarely, presses are supplied with additional lubrication fittings so that water, in addition to
grease, can be metered to the bushings as a lubricant.
Automatic grease systems are available but only usable for fixed (non-rotating) cones. These
should be the high pressure (900 psi) electric or battery variety. Vincent provides these for
critical applications, especially pulp & paper.
Liquid leaking past the cone bushings drains out the back of the cone (at the air cylinder end
of the press). Almost always it is minimal compared to the flow of press cake. However, a
pan can be provided to collect this liquid and drain it into the main flow of press liquor.
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