Screw Press, Fiber Filter, Shredder

The VP Series Screw Presses were introduced in 1952.  Today they are larger, high torque machines, with relatively long screens.  They are commonly used in pulp & paper, corn wet milling, and spent coffee applications, where the press cake requires maximum dewatering.  They feature foot mounted gearboxes; screw diameters start at 16".  The Model VP-16 is popular, so several are built at a time.

The CP Series Screw Presses are also high torque machines.  They feature hollow shaft gearboxes, resulting in a compact machine.  Presses with screw sizes of 4", 6", 10", and 12" are kept in stock.  The Model CP-4, frequently used for laboratory trials, is always available.

The KP Series Screw Presses are our most popular, probably because of relatively low cost.  They are best suited for applications like produce waste, which requires less torque than offered by the VP and CP Presses.  The KP's with screws up to 16" diameter use hollow bore gearboxes, while units larger than that use foot mounted gearboxes.  The screens are not quite as long.  Units 16" and smaller use one air cylinder instead of two to actuate the discharge cone, and they include the rotating cone feature.

Introduced in 2014, the KP-L Series Screw Press features the tapered shaft design, longer screen, and additional compression stages of our aggressive VP Series combined with the lower horsepower requirement and price point of our standard KP Series. This hybrid design offers superior liquid separation capability for lower torque applications such as spent brewers' grain, pectin peel, and fruit juicing.

The TSP Series Screw Presses have two overlapping screws.  They are available with 6" and larger screw diameters.  They are best suited for applications involving very slippery material, those materials which require internal shredding, or installations requiring extraordinarily high throughput capacity.  Because of their cost and complexity, they are not used where a single screw press can do the job.

Vincent Shredders which mount over the inlet of screw presses are available where performance is improved by breaking up the material entering a press.

Similarly, static (sidehill or parabolic) screens are manufactured.  These are mounted over the inlet of a screw press when pre-thickening of the inbound flow is needed in order to optimize performance of the press.  Two designs are offered, with long and short screens.  They are available in widths from 18" to 72".  Wedgewire screens with various slot widths are used.

The Vincent Fiber Filter is a small footprint filter machine with strong non-blinding characteristics.  It achieves fine filtration by using filter sleeves made of woven fabric.  It was originally developed for filtering press liquor ahead of an evaporator.  In recent years its chief application has become filtration of wastewater.

Lime Dosers are used where adding hydrated lime (calcium hydroxide) causes a chemical reaction which releases water which can be separated by a screw press.  Orange peel, potato peel, and tomato waste are typical examples.

All of this equipment is available in the Vincent Rental Fleet.

Vincent started in 1931 by building a Drum Dryer.  These were discontinued in 2007.

For Pressing News application notes that discuss a number of our product applications, click on the links below.

 

AFS Fiber Filter Paper

May 1, 2001

Following three years of testing, the Fiber Filter is being introduced to food processing plants. The machine is a new patented wastewater filtration machine that fills a niche between traditional filtration equipment.

The Fiber Filter works by introducing a flow containing suspended solids into a cylindrical fabric sleeve. The sleeves offered have opening sizes ranging from 20 to 190 microns (0.001 to 0.007 inches). Normally a fabric with holes this small would rapidly become blinded by the solids being filtered from the liquid stream. This problem is overcome in the Fiber Filter by vibrating the fabric at high frequency. The vibration is induced by (a) tensioning the filter sleeves with springs and (b) spinning a high speed (800 rpm) rotor inside the sleeve to induce pulse waves in the fluid being filtered. The rotor has axial paddles that pulse the liquid so as to make the filter sleeve vibrate. The pulsing draws filtered liquid through the fabric; this action has been described as capillary suction.

Small 6" sleeve diameter machines feature a single sleeve, 27" in length. The larger 12" sleeve machines come with either three or four sleeves mounted in series, depending on the capacity and degree of filtration required.

The sleeves in the larger machine are mounted on holders that are free to slide on four tie rods. The holder at the inlet end of the machine is mounted rigid to the tie rods, while the holder at the discharge end is mounted to a sliding member. In this manner the sleeves are stretched taught by springs mounted on the sludge discharge head of the machine.

In addition to axial paddles, the whirling rotor inside the sleeves has helicoid flights. These ribbon flights push the solids toward the sludge discharge end of the machine.

Where heavy concentrations (over 2%) of suspended solids are present in the feed flow, a tight two thirds pitch ribbon flight is used. This rapidly pushes a heavy flow of sludge solids to the discharge. In contrast, thin concentrations (measured in parts per million) of feed solids require a long double pitch ribbon flight. This arrangement removes the solids at a lower rate, resulting in thicker sludge at the discharge and preventing liquid from being ejected from the solids port of the machine.

The fabric used in the Fiber Filter sleeves is a monofilament tweed woven polymer. It is calendared flat on one side, which results in a very smooth surface. This calendared surface is positioned on the inside. This design detail minimizes any tendency for solids to plug or blind the fabric.

If the flow to a Fiber Filter contains excessive solids, these will load up the fabric sleeves. This loading is normally addressed by using a rotor with a helicoid ribbon of tighter pitch. However, if inbound solids are in excess of 4% it is possible for a sleeve to load with solids to the point where machine vibration becomes excessive.

A key application for this machine is at food processing plants with excessive suspended solids in their wastewater. Typically these processors either face a sewer surcharge or have spray field problems. While the dissolved solids cannot be captured, the Fiber Filter does an excellent job of removing suspended fiber.

Fiber Filters have been tested where solids content is extremely low. In one series of tests, capture rates of 75% were measured with feed solids of 1,970 ppm; 50% capture was achieved with 620 ppm feed; and a 25% capture rate with a feed of 204 ppm. This testing was conducted on effluent at a recycle (secondary fiber) paper mill.

A ready market for Fiber Filter exists where the flow to be filtered blinds existing static or rotary drum screens. These traditional screening devices are very economical to acquire and operate. However often they have been put into applications where they are only marginal performers. The Fiber Filter not only features non-blinding characteristics but it also offers finer filtration.

Increased capacity is obtained from a Fiber Filter by using existing sidehill and rotary drum screens as scalpers. The scalping action reduces the tonnage of solids going into the Fiber Filter, thus allowing either greater capacity or finer filtration.

The Fiber Filter was originally developed as a juice finisher. These machines are used to remove pulp from fruit juices prior to concentration in an evaporator. Removing the pulp reduces evaporator fouling. The Fiber Filter has gained its best acceptance as a juice finisher where it is able to replace a centrifuge or decanter.

Vincent Corporation, the designer and manufacturer of the Fiber Filter, is predominantly a producer of dewatering screw presses. Their interest in developing the machine arose primarily from a need to filter press liquor from a screw press. In many cases the press liquor is concentrated in evaporators. The principal products of this process are molasses and juice concentrate. The Fiber Filter has proven superior by offering finer filtration, reduced blinding, and/or reduced operating (maintenance) expense. Notable reductions in evaporator fouling have been achieved with its use.

It is noteworthy that sometimes a screw press is used to further dewater the sludge that is produce by the Fiber Filter. Generally this occurs when the Fiber Filter is used to separate suspended solids from a wastewater flow.

The solids sludge separated by a Fiber Filter will have a consistency in the range of 4% to 10%. When the liquid being filtered is press liquor from a screw press, the Fiber Filter sludge is generally re-admitted to the feed going to the screw press.

The primary adjustment of the machine is made by changing the inclination angle of the sleeve assembly. To filter either low gpm flows or feed flows with higher concentrations of suspended solids, the angle is kept low over the horizontal. In extreme cases the assembly in angled downward.

In contrast, for high gpm flow of dilute solids the sleeve assembly is angled upward as much as 30º. Increasing the elevation angle generally reduces flow capacity and results in higher solids content of the discharge sludge.

In almost all cases a good operating condition can be established by adjusting the elevation angle. In some cases a VFD (Variable Frequency Drive) is used to change the rotor speed. Changing the rotor rpm produces performance changes similar to those achieved by changing the elevation angle.

The Fiber Filter works best with constant gpm feed flow with constant suspended solids content. If the feed or solids vary, the machine is generally set for the most difficult condition. That way satisfactory performance is achieved over a range of flows and consistencies.

The liquid feed need not be pumped under pressure into the Fiber Filter. Gravity feed of liquid from an overhead tank or screw press has proven very satisfactory.

The Fiber Filter is supplied with a backflush system. Backflush is sometimes required to remove deposits from the outside of the filter sleeves. The system is actuated when the solids sludge discharge starts to become watery.

The backflush system consists of spray rings that periodically spray water (or caustic solution or filtrate) against the outside of the sleeves. This is done with the machine in operation. An air cylinder is used to cause the spray ring(s) to travel the full length of the filter sleeves. A timer panel is supplied which allows adjustment of the frequency of backflush. Frequently a booster pump is used to increase flush water pressure to 200 to 250 psi. Such pumps are turned on and off by the timer panel.

Because of the uniqueness of this machine, on-site testing is required of new applications. Laboratory testing is not practical because of the large amounts of feed liquid that are required. A fleet of demonstrator machines is maintained for field trials.

It is expected that the Fiber Filter will gain acceptance in many industries as its performance characteristics become better known and proven.
 

CP Series Presses

February 10, 1995
Rev.November 1997

It was in early 1994 that Vincent began work on the CP-4 Mini-Press. Since then the model has gone through a series of production releases, each incorporating a number of improvements.

This success led to larger scale versions, the CP-6, CP-10 and CP-12. These presses carry the same throughput capacity as the models on which they were based, the VP Series.

The CP Series screw presses are considerably less expensive than the VP's. The reason is that many of the features and options of the VP presses are not available in the CP Series. For example, the CP presses do not have dewatering screens either in the inlet hopper or on the discharge cone. Also, the CP presses are not available with the rotating cone option.

The main reason that the Series CP presses are less expensive to build is that they feature a unitized motor/gearbox that is bolted directly to the first vertical frame member. This eliminates belts, sheaves, a belt guard, a coupling with its guard, and even a pillow block bearing. It also shortens the overall length of the machine.

The Series CP presses have two especially attractive features. First of all, they come with wedgewire screens. These have narrow slots which allow finer filtration than what can be achieved with perforated metal screen. In addition the wedgewire is much stronger than perforated metal.

Secondly, the Series CP presses have a unitized collection pan and horizontal frame. This allows for a very rugged, all stainless steel, construction.

Because of the relatively low prices at which the Series CP presses can be sold, they are opening new markets for dewatering screw presses.

November 1997 note: The newer KP Series presses have taken some sales from the CP Series. The KP's have higher capacities and lower costs; however the CP's can press tighter.

Issue 21

Decanter Tank

July 20, 2003

When vegetable material is squeezed in a screw press, there will be particles of suspended solids in the press liquor. Commonly it is desirable to filter these solids from the liquid. Static screens, rotary drum screens, Fiber Filters, and a variety of other filter machines are employed.

Another devise for separating suspended solids is a decanter tank. This is a simple tank into which the press liquor is allowed to flow. Usually the tank is rectangular, with the flow being admitted to one end. The clarified liquid flows out an overflow connection at the top of the far end of the tank.

Because of the relative size of the tank, flow velocity is so low that solid particles settle to the bottom of the tank. Sometimes labyrinth panels are placed in the tank, sending the flow in a circuitous path. Alternatively, a series of three tanks are used, connected by overflow weirs, one flowing into the other, each at a slightly lower elevation than the previous.

Decanter tanks work best where the suspended solids are significantly heavier than water. A good example is to be seen at a Starbuck's soluble coffee plant. The spent grounds are dewatered in a Model CP-10 screw press. The press liquor goes to a decanter tank where fine particles settle out. This clarifies the press liquor to where it can be sewered. Once a week an operator shovels the solids out of the tank.

Other applications for decanter tanks include separating starch from the press liquor that results with potato peel is dewatered, and separating fines from the press liquor that results from dewatering chili pepper that has been dried, ground, and re-hydrated. Another use of decanter tanks is to allow oil to float to the top when whole limes are crushed and pressed in a screw press.

Dairy farmers that use sand bedding for their cows use a variation of the decanter tank. In order to dewater the manure in a screw press, it is necessary to first separate the sand from the manure. This is done in huge concrete troughs. Flow velocities are set so that the sand falls out of the flowing stream, while the manure particles remain suspended in the liquid. This liquid is pumped to the screw press. Periodically a front-end loader is used to remove the sand that fills the trough.

Issue 143

Dryer Description

Note:  VINCENT CORPORATION WITHDREW FROM THE DRYER BUSINESS IN 2007.

IT WAS A GOOD RUN, FROM 1931 TO 2007.  To fill your needs, you are referred to

 

Vincent drying systems convert waste foodstuffs from many industries into profitable by-products.

The Vincent Vacuo-Dehydrator removes moisture from a continuous flow of material. It is a direct fired dehydration system available in sizes ranging in capacity from 1,000 to 20,000 pounds per hour of water evaporation.

The Vincent Dehydrator is a three pass rotating drum machine with special lifting paddles on the inner and outer surface of each pass. The curtain formed by the material falling from these paddles as the drum rotates assures that all material being fed to the unit receives maximum exposure to the warm gas stream. The drum design and gradually reducing temperatures serve to form an operational balance between declining gas flow energy and declining material moisture content, thereby reducing the chances of burning the product or having it stick to the walls.

Upon leaving the Dehydrator, the material is separated from the air stream in a uniquely designed "low intake" Expansion Chamber. The dried material is drawn through this combination separation and drying chamber under vacuum stream conditions while being cascaded through the hot air stream.

A conventional "high inlet" Cyclone Separator can also be employed. This second devise can be installed in series with the Expansion Chamber when a natural grading of material size is desired.

The Vincent Dehydrator drum is available either in the rotating or stationary outer shell design. The stationary outer design allows the capability of re-cycling partially dried material. Many soupy or sticky materials, which are difficult to dry in most dehydrators, are effectively handled in the Vincent Dehydrator.

When specified with this recycling capability, the Dehydrator allows partially dried material to be mixed with incoming wet material, absorbing excess moisture. In this manner the moisture becomes distributed through a greater number of particles, allowing the mixture to dry easily and quickly. This mode of operation does not reduce the capacity of the Dehydrator.

Operation with the recycling feature is automatic and continuous, yielding high product quality with a minimum of operator attention. Extraction gates allow easy adjustment to compensate for changes in product consistency.

The Dehydrator is fed by a variable speed air lock screw conveyor. This can be easily adjusted through a wide range of speeds to match variations in required evaporation rates.

The Vincent Dehydrator drum is completely assembled and aligned for ease of installation. All parts subject to thermal expansion are provided with expansion joints, resulting in long trouble free operation. The unit is mounted on a rigid frame, which minimizes the cost of the concrete foundations and which keeps the machine in better alignment. The standard drive arrangement for the Vincent Dehydrator is a heavy duty gear reducer, mounted on a jackshaft with roller bearing pillow blocks.

All models are of fabricated design and are available in carbon steel, partial stainless, and all stainless construction. The drum assembly turns on machined steel tires at either end which are supported by roller bearing trunnions.

PRINCIPLES OF OPERATION
Material enters the Vincent Dehydrator drum at the furnace end through the throat, and removal of water begins immediately. The evaporation of water maintains the product temperature at the dew point condition where the highest efficiency of evaporation occurs.

A temperature monitor at the inlet to the third pass of the drum senses any variation in gas temperature. This correlates to the moisture in the product and automatically adjusts the fuel supply to the furnace. This controls the moisture content of the dried product. Moisture content of plus or minus 1/2% on overall product dryness at pre- determined levels can be attained.

Material is drawn through the concentric drums by the exhaust fan vacuum. As the material dries the density decreases so that it is drawn further through the Dehydrator until only particles of the required moisture content pass out of the drum. The possibility of damage to the product by high temperatures is avoided in the process.

EXPANSION CHAMBER AND CYCLONE SEPARATOR
The Expansion Chamber is fitted to the output end of the Vincent Dehydrator. It is a large tank in which the dried material is separated out of the hot air stream. Material collected in the chamber is then screw fed out of the base through an air lock.

 

MODEL FOOTPRINT SYSTEM
POWER
REQUIREMENT
HEAT INPUT
'000 BTU/HR
WATER
EVAPORATION
(LB/HR)
10 5'3" x 34' 10 hp 1,760 1,000
25 7'6" x 48' 20 hp 4,000 2,500
50 8'6" x 60' 37 hp 8,000 5,000
75 9'6" x 66' 50 hp 12,000 7,500
100 10'3" x 70' 63 hp 15,000 10,000
150 11'6" x 76' 84 hp 22,500 15,000
200 13'6" x 88' 125 hp 30,000 20,000

VINCENT DIRECT HEAT FURNACES
Vincent Furnaces are designed to form part of a complete Dehydrator system, which includes the Controls, Burner, Furnace, Dehydrator, Expansion Chamber, and Exhaust Fan. Each furnace is performance matched to supply direct heat to the product. Furnaces can be fired with heavy or light fuel oil, or natural gas, or they can be fitted with combination burners. In addition the furnaces are designed for either direct flow-through of the hot gases or they may be designed to recycle part of the heating gases. The selection depends on the type of material to be dehydrated.

The standard furnace configuration allows the products of combustion to pass directly through the drum, separation equipment and out the stack. In more demanding situations provision is made to recirculate a portion of the gasses from the discharge of the separation equipment back to the inlet of the furnace. This arrangement both reduces dryer temperatures and increases the combustion of noxious fumes and combustibles.

A final option available is an afterburner furnace. This is used where there is a severe need to oxidize fumes and particulates prior to discharge to the atmosphere.

Fiber Filter I

July 21 1998

Vincent Corporation is introducing an exciting new product, the Fiber Filter.  Featuring fine filtration of low consistency, high gpm throughputs, the Fiber Filter is a unique machine.  There is nothing quite like it available in the market.  It operates continuously with a fabric filter that is vibrated clean by the process flow, requiring only occasional back-flush cycles.

Liquid flows with fiber contents ranging from 100 ppm to 2.0% are thickened to a range of 2% to 10% solids with the Fiber Filter.  The filtrate liquid is remarkably free of suspended solids.  The Fiber Filter can replace equipment ranging from pre-thickening screens to centrifuges.  Fiber Filters can be used both to thicken flow ahead of a screw press and to remove fiber from press liquor.

Mechanically the Fiber Filter consists of a rotating paddle impeller that whirls and pulses the incoming fluid against the inside of a cylindrical filter screen.  The filter screen, held taught in a frame, is made of woven polymer fabric.  The fabric is available in meshes ranging from 600 (25 microns or .001") to 70 (200 microns or .008").  The angle of inclination of the machine is adjusted to optimize flow rate and solids concentration.

External Fabric Tensioning is an important innovation.  The springs that hold the fabric sleeves tight are tensioned at the discharge of the machine.  This allows adjustment of the fabric tension with the machine in operation, an important operator convenience.  Also, it eliminates springs, turnbuckles and threaded rod from the inside.  This is important where the application involves products for human consumption because the machine becomes much more sanitary.  There is a patent pending on this feature.

To date, only the engineering prototype and a short production run of FF-12's have been produced.  These units are being placed in the rental fleet so that they can be used for field testing.  Our key target applications for testing are: press liquor in food processing plants, breweries, and citrus feedmills; whey in the cheese industry; residual fiber in wet corn milling ethanol plants; screen rejects, black liquor and clarifier underflow in the pulp and paper industry; press water in manure dewatering operations; and juices.

Rental units are available on a first come, first served basis.  The machines are all-stainless.

 

Issue 80

Fiber Filter II

February 5, 1999                                                                                                                                                                                                    ISSUE #90

After a year of testing, Vincent Corporation has gained a great deal of confidence in the Fiber Filter. It is a unique filtering machine that has broader market application than our traditional screw presses, dryers, and shredders. Once the newness is overcome, it is easier to sell.

The best place to test a Fiber Filter is where a centrifuge is being used. If the Fiber Filter works, it is a sure sale because its total cost is less than the routine maintenance of a centrifuge. There are applications in both fruits and meats where the performance of the Fiber Filter beats that of a centrifuge.

Another ready market for Fiber Filter is where the flow to be filtered tends to blind existing static or rotary drum screens. These traditional screens are very economical to acquire and operate. However they have been put into many applications where they are only marginal performers. The Fiber Filter not only features non-blinding characteristics but it also offers finer filtration.

Here is how a Fiber Filter works. A flow containing suspended solids is pumped into a fabric sleeve. The sleeves offered have hole sizes ranging from 0.001 to 0.006", which is finer than is available in metal screens. Normally a fabric with holes this small would rapidly become blinded by the solids being filtered from the liquid stream. This problem is overcome in the Fiber Filter by vibrating the fabric at high frequency. The vibration is induced by (a) tensioning the filter sleeves with a pair of springs and (b) a high speed rotor inside the sleeve induces pulse waves in the fluid being filtered. These pulses of liquid make the filter sleeve vibrate.

The whirling rotor also has flights to push the solids toward the sludge discharge end of the machine. At the same time the pulsing forces filtered liquid through the fabric.

Applications which promise success include:

Because of the newness of this technology, we do not expect a firm to buy a Fiber Filter without first testing it. For that purpose a rental fleet is available. The small FF-6 rents for $200/week; the FF-12 for $350. The customer must also pay the freight to and from the test site.
 

KP-16 Improvements

May 20th, 2008

When Ford Motor Company introduced their 1950 Ford, at the start of a new decade, they were very proud. Every dealership had a big poster with a banner headline, "FIFTY IMPROVEMENTS IN 1950". Fifty different items, including carburetor and generator changes, were listed.

Today the most popular screw press offered by Vincent is the Model KP-16. A recent production run included the following ten improvements:

    • Resistor Bar: The resistor bar has been modified to allow the screen to face either direction. This means that the screen can be reversed for double the previous life expectancy. A handle on the resistor bar prevents it from being inserted incorrectly.
    • Tailstock: The tailstock assembly has been altered to allow adequate space for using a magnetic drill in the shop. During assembly the tailstock is tapped and shimmed where screw-to-screen alignment is best. Then it is clamped in place, and the mag drill is used to bore the holes for the bolts connecting the tailstock to the bed frame. Also, a plate which provided axial support for the tailstock has been removed because it was deemed no longer necessary.
    • Bed Frame: As the result of the tailstock modifications the bed frame has been shortened three inches. Also, one of the channels which support the tailstock has been turned to face the C-plate. The tailstock should be much easier to remove.
    • Drive Wheels: The drive wheels for the rotating cone feature are 1" thick by 8" diameter, with a bronze bushing and steel axle. This is a new drive design implemented on all Series KP presses. The machined bushings and axles ensure the wheels turn straight. The larger diameter reduces the number of turns the wheels make.
    • Rocker Arm: The yoke has been widened from 12" to 15". This puts the drive wheels farther out on the cone's racing ring. The farther the wheels are from the center, the smaller the angle of rotation the wheels are forced to bear.
    • Screw Shaft: The OD of the screw shaft will be 6" instead of the previous 4". This may decrease capacity of the press slightly in some cases, but it should increase dewatering capability. That is, there is less distance for water to travel to get to the screen, so press cake should be drier.
    • Catch Pan/Covers: The covers fit into the press liquor catch pan 3" lower than before. This allows more access to the screen and the discharge flange, making cleaning and repairs easier.
    • B-plate Screen Centering Ring: The screen positioning ring at the B-plate is now a single piece, with a 1" gap to serve as a cord cutter.
    • Cone Bushing: The cone bushings will be made of UHMW instead of green nylon. UHMW will be less prone to seize to the shaft as it expands less due to water absorption.
    • Racing ring: The racing ring, on which the wheels track, is now made of glass-filled UHMW. Increased life is expected.

Issue 199

Model KP-24

May 24, 2002, Revised 2008                                                                                                                                                                                   ISSUE #124

Our Model KP-24 screw press has gained acceptance since its introduction in 2002. With a 24" diameter screw, this is the now the second largest of the Series KP "soft squeeze" screw presses. The first machine was produced for rental to Lakeside Packaging, where it is currently used to dewater cornhusk and cob waste at a sweet corn cannery.

Design of the press reversed the normal procedure. It started by selecting the largest helical gear speed reducer offered by SEW-Eurodrive, the Model 157. A reduction ratio was selected that would allow an ample service ("safety") factor. At the same time the possibility of switching to a larger motor, should it be required, was left open. Once this was done, the largest acceptable screw diameter was selected, which happened to be 24".

Since then Vincent has standardized on Nord gearboxes, which allowed the development of the even larger Model KP-30.

The first KP-24 had a 40 hp motor, with a screw speed of 22 rpm. If necessary, the motor can be changed to 50 hp, still leaving adequate service factor. For applications requiring more residence time in the press, such as dewatering pectin peel between wash tanks, lower screw speeds and 20 hp motors are specified.

Vincent prefers to use standard American NEMA motors. On request we supply a European IEC motor instead. This eliminates the need for an adapter between the motor and the gearbox, significantly shortening the overall length of the unit.

At the time, other Series KP screw presses used a flat door at the cake discharge, actuated by a 4-bar mechanism. This proved disproportionately large in the KP-24, so a new design, using a conical door and a single air cylinder, was developed. The design worked out so well that it is now standard on all of the smaller Series KP screw presses.

The KP-24 screen was made of 3/32" perforated stainless. This was a one-piece assembly which proved difficult to handle in the field. Today the screen is split in two halves, removable from the sides of the press. This has greatly facilitated maintenance.

All smaller Series KP presses have had a single resistor bar. However the relatively large diameter of the KP-24 has resulted in the use of two resistor bars. At the same time, the KP-24, as with the other KP's, has three stages of compression. This, along with the high screw rpm, gave the high capacity, soft squeeze characteristic to the KP presses.

(Today low speed versions of the Series KP presses are finding increasing popularity because, in some applications, they can achieve the same performance as our longer, more expensive presses.)

CP-4 Laboratory Press

January 16, 2002
June 2010 Revision

First introduced in 1994, the little Model CP-4 screw press has proven a steady seller. The largest single market is laboratories, although most sales fall in a wide range of miscellaneous. Until the advent of the Model KP-6, the press was a popular in the plastics recycling industry for dewatering wash tank sludge. Recent applications include pressing cranberries, egg shells, nutraceuticals, crumb rubber, sludge from sidehill screens, fish waste, alfalfa, and orange juice pulp.

With each production run a review is made for possible improvements. We are now in our 29th production release! Looking back we see that the press has gradually become more powerful, safer, and more reliable. Just like automobiles.

The CP-4 is extremely handy to use because it can be plugged into any 110-volt wall outlet. Also, the capacity is such that it can be conveniently fed from 5-gallon pails. We have over thirty of these in our rental fleet, so there is almost always something available.

The 4" screw of the press is driven by a hollow shaft gearbox. Motors ranging from 0.5 to 7.5 hp can be supplied, although 1-1/2 hp is most common. As with the original prototype, the screen is profile bar with 0.015" slot width, with four stationary resistor teeth.

To regulate the moisture content of the press cake, an air cylinder actuator is used to position the discharge cone. This replaces the weight arm and spring actuators used in some earlier versions.

The latest CP-4 looks quite different from predecessors. Previously either a side yoke or an overhung arm supported the tail bushing. The new units have an outboard pedestal support. The advantage is better visibility of the pressing operation, with less opportunity for the press cake to hang-up at the discharge.

The inlet hopper features a vertical wall on one side and a sloped wall on the other. The vertical wall is used to minimize bridging of material in the inlet hopper, while the sloped wall is employed to maximize hopper capacity.

Units are frequently customized. Stands with wheels are available. Three phase motors are provided for variable speed operation. Gearboxes can be changed for different screw speeds; and the pan can be modified for a bottom (instead of side) drain. Various screw options, including hardsurfaced, notched, and step-shaft, are offered. On occasion the press is made vapor-tight, with an explosion proof motor.

 

  

MODEL CP-4 SCREW PRESS SHOWN WITH SCREEN COVER REMOVED.

 

Issue 124

 

 

 

 

New KP-6 Press

March 13, 2002, Rev. November 2010                                                                                                                                                                      ISSUE #126

 

First introduced in 1996, the economical Model KP-6 screw press gained rapid popularity. Initially the largest markets were plastics recyclers and small dairies and hog farms. Today, the most popular application is albumen recovery from egg shells. Other industries now using the machine include canneries, meat processors, medical waste disposal, and a range of food processors.

With each production run, value analysis is conducted to add improvements. Already in its twenty-ninth production release, the machine exhibits many changes over the original prototype. The principal improvements are (a) the addition of an outboard pedestal and bushing so that the screw shaft is supported at both ends, (b) gearbox and screen mounting which assure rigid screw/screen alignment, and (c) the use of a split clamshell screen assembly. This change to the screen facilitated both manufacture and maintenance.

Originally the Series KP presses were designed for "soft squeeze", high capacity applications. However, supporting the screw at both ends assures that the screw will not drift into the screen even under high torque applications. This modification has allowed the optional use of lower speed gearboxes to meet tighter squeezing applications.

After poor experience with Sumitomo, SEW Eurodrive, and Radicon hollow shaft gearboxes, Vincent found the Nord gearbox. These all come with input bearings rated for 4000 rpm. In addition, Vincent specifies heavy-duty output shaft bearings. These, being roller bearings rather than ball bearings, carry extra axial loading. The best Nord feature has been their simple keyed drive, which allows easy removal of the screw even after years of service.

A major improvement is the rotating cone feature, which is now standard. This construction offers advantages in about half our applications.

Current KP-6 presses still use the original screen length and inside diameter (6"). The flat discharge door has taken a modified cone shape. The cone actuator now provides axial movement, which is a significant improvement over the original pivoting action. A version with a 4-bar mechanism eliminates the cone bushing in highly abrasive applications.

A number of options are available: 1, 2, and 3 hp drives; screw hardsurfacing and notching; weights (instead of an air cylinder actuator for the discharge door); and a choice of perforated metal screen or slotted wedgewire. Even a short model, with no screw interruptions or resistor teeth, has found applications. Versions with long inlet hoppers, used where the press is being fed directly from a belt conveyor, have been sold. All in all, the press has proven a remarkable success in the market place.

 

Press and Shredder Combination

March 13, 2007                                                                                                                                                                                                    ISSUE #185

An unusual feature of the Vincent Series TSP twin screw presses has come to have important application possibilities. The screws of the Vincent twin screw presses, like all Vincent press screws, feature the interrupted flight design. This means that there are places on the shaft of the screw where there is no helicoid flighting. The flights after each of these gaps constitute an additional compression stage in the press.

Stationary resistor teeth project through the screen of the press into the gaps where the flights are missing. The screws used in the twin screw presses have seven such compression stages, so there are fourteen teeth, seven on the top and seven on the bottom. However, since there are two screws in each press, a total of twenty-eight teeth are employed in Series TSP machines.

There is a tendency for the teeth to shred material that is being dewatered in the press. This effect is multiplied in twin screw presses because the two screws overlap each other. This creates especially aggressive tearing action within the press.

The shredding effect of the twin screw presses was noted with the initial prototype. Any time material, even previously shredded material, was admitted to the press, the cake was noted to consist of smaller sized particles.

This characteristic was put to test with material from the Del Monte sweet corn cannery in Sleepy Eye, Minnesota. Corn husks and cobs were fed, un-shredded, into a Model TSP-6 press. It was readily apparent that the final press cake was made up of smaller particles than the same material that was shredded in 75 hp shredders (prior to being dewatered in the Model KP-30 press at the same location).

Following this success, a Model TSP-12 was installed at the Birds Eye sweet corn cannery in Waseca, Minnesota. The drive was changed to obtain more than triple the brochure screw rpm (52 rpm); the motor horsepower was doubled from 30 to 60 hp. The results were huge throughput capacity. More importantly, the resulting press cake was shredded to acceptable particle sizes without the use of a hammer mill.

Since then additional testing has been conducted. Notable success was found feeding un-shredded produce waste and salmon fish waste into twin screw presses. In both cases, excellent shredding was achieved inside the press.

The potential to eliminate the need for a shredder is exciting. Eliminating the shredder obviously reduces capital investment and future maintenance needs. In addition, the high decibel level associated with the shredder is eliminated, as is a significant motor electrical energy requirement.

The improved feeding characteristics of twin screw presses over single screw presses are one more plus in the equation. Large items like whole melons and cabbage heads feed through the press without difficulty.

Frozen Pulp Fluidizer

SPECIAL DESIGN: Low speed, double drum type, pulp fluidizer.

The Pulp Fluidizer was developed to enable pumping frozen blocks or chubs of fruit pulp while maintaining the highest level of flavor characteristics. The machine has found acceptance in fluidizing frozen pulp and pomace from both deciduous and tropical fruits. It is also used, as convenient, to liquify frozen juices in blending and not- from-concentrate operations.

The unit is a premium machine in that blocks are fluidized with a very minimum of damage to cell and fiber structure. It is a double drum type fluidizer that turns at a relatively low speed (520 rpm). These two features assure minimum disturbance to the materials being fluidized. In the machine, product is reduced to a fluid state by mechanical means. No heat is added, and, with the addition of some water (or heat from another source), the product becomes pumpable.

Specifications include:

 


Option: 3" Tri-Clamp sprayball connection and sprayball for CIP service.

Capacity is 30 to 40 frozen blocks of approximately 5 gallons each, per hour.

Ref: Drawing A-91424.

Pulp Fluidizer

October 2, 2001

In citrus juice operations there frequently is a need to handle frozen pulp. This pulp is filtered from juice in either Brown or FMC finishers, and then frozen. It is most commonly added back in orange juice blending operations. It can also be used in preparation of juice flavored soft drinks.

Originally developed for Minute Maid juice blending operations, today the Vincent Pulp Fluidizer is used by almost all of their co-packers.

The machine enables pumping frozen blocks of citrus pulp. Blocks in up to a five gallon size are fluidized with a very minimum of damage to cell and fiber structure. Since the operation is performed at low speed and without the application of heat, the highest level of flavor characteristics is maintained.

The original machine has found acceptance in fluidizing frozen pulp and pomace from both deciduous and tropical fruits. It is also used, as convenient, to liquefy frozen juices in blending and not-from-concentrate operations.

Designated The Model PF-1416-K7.5, the machine is described as a low speed, double drum pulp fluidizer.

The pulp is reduced to a fluid state by mechanical means. With the addition of some water (or heat from another source), the product becomes pumpable.

Features:

Screen Flush Systems

September 2, 2008                                                                                                                                                                                               ISSUE #202

Once or twice a year Vincent supplies a screw press with a spray system for cleaning the outside of the screens. This is usually either in food grade applications where USDA regulations require wash down, or in vapor-tight presses where alcohol solutions foul the outside of the screens. The need can also arise on spent grain, where starch cakes on the screens.

These systems usually use high pressure water. Vincent supplies a 5 hp pump to boost the pressure of the plant water to about 225 psi. This makes the cleaning more effective. We mount the pump on a stand with a filter (to keep scale and such out of the nozzles), plus a timer to turn on the pump and open the solenoid valve in the water line, plus another solenoid to send air to the air cylinder that runs the spray rings back and forth. This is shown in the photo.

We did one job where the customer hooked up piping for three fluids: water, caustic and acid. That way they wash with three different liquids, in a sequence that washes off the chemical solutions at the end of the cycle, with water.

We supply these systems either with fixed spray nozzles or with traveling spray rings. With the fixed nozzles, we have four manifolds running the length of the screens, one each at the top right hand, top left hand, bottom right hand, and bottom left hand. These nozzles use a conical spray pattern.

One customer has only two manifolds, at the top of the press. They use a caustic solution that starts at the top and flows by gravity to clean the bottom half of the screens.

With traveling spray rings we use an air cylinder to run the spray back and forth. These nozzles have a fan spray pattern, and they do a more effective job of washing. In presses with long screens, we use three spray rings, each traveling 30", driven by an air cylinder with a 30" stroke.

We recently retrofitted wash systems to a pair of 16" presses in a citrus plant. They did not need the booster pump because they already had high pressure water in the area. The system is not on a timer; they run manually when washing is needed.

A major design consideration is allowing for the screens to be removed from the press without interference from the spray piping.

 

Screw Press Description

The Vincent horizontal continuous press is a dewatering machine with a conveying screw rotating inside a perforated cylinder. Incoming material is forced the length of the machine, liquid "press liquor") is expelled through the cylinder wall. The remaining solids ("press cake") are discharged at the far end.

The press is available in sizes with screws ranging from 4" to 30" in diameter. The screw has a graduated pitch, interrupted flight design. This screw interacts with stationary resistor teeth. These teeth assure that the material to be pressed (1) does not turn (co-rotate) with the screw and (2) is intermixed during passage through the press. Because of this, more material is exposed to the screening surface.

The graduated pitch screw gradually compresses the material as it passes through the main screen cylinder of the press. The press liquor is forced through the perforations in the screen.

The press cake encounters resistance at the discharge of the cylinder in the form of a cone mounted on a ram. As the material reaches the discharge point, the cone exerts final pressing action to achieve maximum dewatering. The cone system allows easy adjustment of the resistance to cake discharge.

This cone assembly may incorporate a unique discharge pinch point, described in a patent as a frustum, the converging angle formed by the cone face and main screen section. The change in direction as the press cake enters this area assures fresh material contact with screen surface. This converging pinch area has proven to give excellent final pressing action.

Air cylinders, springs, or counterweights actuate the cone assembly, depending on the model. It is available in both rotating and non-rotating versions. The standard, non-rotating cone is used for pulpy, fibrous and less slippery materials, while the revolving cone model is required to permit pressing of slippery, low fiber content materials that tend to "channel" in a standard screw press.

The design features of the Vincent Series VP Presses give greater screen areas than found in conventional presses. The hopper section has a screen area covering 180º of the periphery of the screw to allow drainage of free water. The main screen section has a full 360° screen area, approximately four screw diameters in length. The cone assembly also has a screen area with a separate drain pan.

The standard drive arrangement for the Vincent Press is a gear reducer directly coupled to the screw shaft. Variable speed drive arrangements, although rarely used, are available to allow maximizing capacity as feed characteristics change. This type of drive is recommended either when different products are to be processed or when major seasonal variations occur.

The press is fed from the top at the drive end through a rectangular flanged hopper. The press cake discharges at the far end, between the bedframe beams below the cone section. Press liquor drainage is through standard or sanitary pipe connections; these are attached to the pan under the screen section.

CAPACITY: The rated capacity of the Vincent Continuous Screw Press is proportional to the bulk density of the material to be pressed, as well as the slippage characteristic of the material. The ability of the material to give up its moisture, its particle size, and its fibrous content are factors to be considered. The high capacity of this machine, its low head room requirement, as well as low horsepower factor, are some of its many advantages.

The capacity and the water removed during pressing can be varied by adjusting the cone pressure. Adjusting this pressure assures maximum dewatering over a wide range of feed rates, permitting good turndown from rated capacity.

SCREENS:The screen frames can be readily opened or removed for ease of cleaning and screen maintenance. The screens of the Vincent Press are available in a variety of arrangements and screen perforation sizes, commonly in the 0.023" to 0.095" diameter range. With wedge wire screens, 0.012" to 0.030" slots are commonly used. Selection is determined by the material being pressed and the desired pressing results.

MAINTENANCE: The Vincent press has been recognized for the exceptionally low maintenance costs associated with it. Easy access to all component parts keeps maintenance time to a minimum. Use of off-the-shelf components (gearbox, bearings, air cylinder, etc.) reduces maintenance costs and assures trouble-free operation. The all-fabricated design facilitates in-plant repairs should they become necessary.

MATERIALS OF CONSTRUCTION: All press models are of fabricated steel design. They are available in all stainless construction, partial stainless, and carbon steel, as follows:

H style presses are carbon steel construction, except for the perforated screening, covers, and drain pans, which are made of Type 304 stainless steel.
P style construction has (in addition to stainless steel covers, drain pans and perforated screening) a Type 304 stainless steel screw-spindle assembly.
K style construction has all contact parts, i.e. screw-spindle assembly, resistor-stop bars, screen frames, hopper and cone sections, of Type 304 stainless steel.
Special construction of Type 316 stainless steel is available. The bedframe is of carbon steel.
SERIES: There are four Series of Vincent presses available: the TSP, VP, CP, and KP.

The newest Vincent Press is the TSP Series. These have two overlapping screws. This design offers positive feeding of even very slippery materials. The best dewatering performance over the widest operating range is available in this press. The capacity and performance of the press is sensitive to changes in screw rpm, so the use of a VFD is recommended.

The traditional Vincent Press is the VP. These are differentiated by having screens in the inlet hoppers; a flared section in the main screen just ahead of the discharge cone; a single air cylinder cone actuator; and (usually) a belt drive between the motor and gearbox.

The Series CP (Compact Press) features a hollow shaft gearbox and a simplified cone drive, both of which shorten the frame of the machine. There is no screen in the inlet hopper, and profile bars screens are almost always used. These presses are available only in stainless steel construction.

The Series KP presses are designed for a "soft" squeeze. They dewater high throughputs of easily dewatered materials. Instead of a discharge cone, they use a lever actuated stopper plate. Perforated screens are used in almost all cases. Only stainless steel construction is available.

TEST FACILITIES: To conduct tests Vincent Corporation maintains laboratory and pilot equipment. Feed rates, moisture contents, percent solids, effluent characteristics, and horsepower requirements can be determined from test data.

A large fleet of rental machines are available for in-plant trials.
 

Series CP Press Options

February 25, 2005                                                                                                                                                                                                 ISSUE #158

An e-mail recently received, via our web site, read as follows: "I am building a proposal for a client and have a need to know the cost and delivery for a Model CP-4 horizontal press." Not revealing what material is to be pressed, why, how much per hour, or any other similar specification can lead to trouble later on. One way to address this is to be aware of the options that can be built into these small screw presses:

 

 

 

 

 

 

 

There is no change in pricing for these last two options. However, the factory obviously needs to know about it.

 

Shredders

May 29, 2012
 

Frequently a screw press performs better if material is shredded before being admitted into the press. For that purpose Vincent Corporation offers a line of shredders. These are sized to bolt directly onto the inlet of Vincent screw presses.

The Vincent shredder is a horizontal machine with a 180 degree discharge area on the underside. It is ideally suited to bulky materials, such as citrus peel, whole fruit, and produce waste.

The blades rotate about a horizontal shaft. They are fixed; they do not swivel. The blades are made of hardened 410 stainless, and they are keyed to the rotor. The blades are sharpened at a 45 degree angle when slicing, as opposed to mashing, is required.

The material being shredded is forced through the discharge of the machine. The material can be thrown through a screen, a comb, or a free opening, depending on the machine configuration. The VS models have a screen mounted in the discharge, while the VCS models have a comb (or grille) in the discharge. A tooth from the comb fits between each pair of rotor blades.

The VCS models are very susceptible to serious damage if rigid tramp material, such as tools or rocks, fall into shredder. Also they are susceptible to jamming on start-up if material is left in the machine. For this reason they are commonly used without the comb in service.

A variety of screen sizes are available for those models which use screens. Typically these are in the range of 3/4" to 2", generally in the form of square-round holes. Screens are made of either 304 stainless or carbon steel.

Large shredders are typically fed with a screw conveyor. Since the shredder throws material upward as well as downward, it is important to have a cover over the screw conveyor trough at the shredder.

8" and 12" shredders are frequently used for laboratory and pilot operations. Where these machines are batch fed, a dogleg inlet chute should be used to prevent throw-back material from making a mess or causing injury.

Shredder housings can be either split or hinged, so as to allow ease of clearing jams, changing rotors, or replacing screens. In operation the upper part of the housing fits folded around the inlet chute, or it is bolted to the bottom flange of an inlet chute.

Vincent shredders are powered by premium efficiency electric motors. These are direct coupled to the rotor shaft. Some models, with two bearings, use Dodge Para-Flex couplings. Other models, with one outboard bearing, use rigid couplings.

Vincent shredders use 304 stainless for parts that are in contact with the material being shredded. Base frames are made of mild steel.

MODEL ROTOR
DIAMETER
MAXIMUM
CAPACITY
LB/HR
INLET &
OUTLET
DIMENSIONS
WEIGHT DIMENSIONS
BASE BY
HEIGHT
MOTOR
HP
VS-8 & VCS-8 8" 5000 8" x 8" 300# 12" x 36" x 16" 5-15
VS-12 & VCS-12 12" 10000 12" x 12" 800# 16" x 48" x 20" 10-20
VS-18 & VCS-18 18" 40000 18" x 18" 1600# 24" x 60" x 30" 30-50

DIMENSIONS AND WEIGHTS ARE ONLY APPROXIMATE.

THROUGHPUT CAPACITIES VARY CONSIDERABLY. THEY ARE SUBJECT TO ON SITE TESTING.

VINCENT CORPORATION, TAMPA, FLORIDA, USA

TEL: 813-248-2650 WWW.VINCENTCORP.COM

Shredders History

September 23, 2010                                                                                                                                                                                             ISSUE #226

HISTORY of VINCENT SHREDDERS

Vincent started making shredders in the 1930's, to improve the capacity of the dryers we operated (making cattle feed out of orange peel).  Today we still offer shredders, but generally for the limited applications with which we are familiar:  citrus waste, pineapple juice, and produce waste.

Vincent made shredders with vertical shafts, but these had severe maintenance problems.  The main difficulty related to the lower bearing being in liquid from the shredded material.

In 1968 the Rietz company merged with Vincent.  They took our screw press designs, and we dropped our vertical shredder in place of their Rietz RD-18, which is a much better vertical shaft shredder.

That deal soon fell apart, and Vincent resumed making their own shredders (or hammer mills).  These shredders had a horizontal shaft with a screen surrounding the lower 180 degrees below the rotor.

These shredders were designated Series VS, for Vincent Shredder.  We have two versions of these shredders:  thin blades and thick blades.  The thin blades were used to slice lime and lemon peel in pectin peel washing operations.  The thin blades were susceptible to damage from tramp metal.  Thick blades hold up better to tramp material and are used in shredding orange peel to make cattle feed.

A few years ago we came out with the Series VCS shredders:  Vincent Comb Shredder.  The blades of the rotor fit between fixed teeth.  These fixed teeth form a grill or comb.  They run from one side of the housing to the other.  As the blades of the rotor spin, there is a scissors action, slicing the material.  (There is no screen.)  Most of these operate without using the comb, just doing a rough pre-breaking.

Vincent offers shredders primarily as an accessory machine to go with our screw presses.  We keep a few in the rental fleet.

8" LABORATORY SHREDDER - MODEL VCS-8

VINCENT PRODUCT LINE OVERVIEW

Having evolved from a builder of turn-key citrus feedmills, Vincent today has become the leading designer and manufacturer of screw presses.

We offer four Series of Screw Press designs, each with half a dozen different screw diameters. 

We also build machines which may be required for use in conjunction with screw presses.  These machines are primarily pre-thickening screens, shredders, the Fiber Filter, as well as lime dosers. 

In addition we keep available rental equipment such as pumps, tanks, agitators, and rotary drum screens.  These machines are available for pilot testing involving screw presses.

The Series VP Screw Presses were introduced in 1952.  Today they are larger, high torque machines, with relatively long screens.  They are commonly used in pulp & paper, corn wet milling, and spent coffee applications, where the press cake requires maximum dewatering.  They feature foot mounted gearboxes; screw diameters start at 16".  The Model VP-16 is popular, so several are built at a time.

The Series CP Screw Presses are also high torque machines.  They feature hollow shaft gearboxes, resulting in a compact machine.  Presses with screw sizes of 4", 6", 10", and 12" are kept in stock.  The Model CP-4, frequently used for laboratory trials, is always available.

The Series KP Presses are our most popular, probably because of relatively low cost.  They are best suited for applications like produce waste, which requires less torque than offered by the VP and CP Presses.  The KP's with screws up to 16" diameter use hollow bore gearboxes, while units larger than that use foot mounted gearboxes.  The screens are not quite as long.  Units 16" and smaller use one air cylinder instead of two to actuate the discharge cone, and they include the rotating cone feature.

The Series TSP Presses have two overlapping screws.  They are available with 6" and larger screw diameters.  They are best suited for applications involving very slippery material, those materials which require internal shredding, or installations requiring extraordinarily high throughput capacity.  Because of their cost and complexity, they are not used where a single screw press can do the job.

Vincent Shredders which mount over the inlet of screw presses are available where performance is improved by breaking up the material entering a press.

Similarly, static (sidehill or parabolic) screens are manufactured.  These are mounted over the inlet of a screw press when pre-thickening of the inbound flow is needed in order to optimize performance of the press.  Two designs are offered, with long and short screens.  They are available in widths from 18" to 72".  Wedgewire screens with various slot widths are used.

The Vincent Fiber Filter is a small footprint filter machine with strong non-blinding characteristics.  It achieves fine filtration by using filter sleeves made of woven fabric.  It was originally developed for filtering press liquor ahead of an evaporator.  In recent years its chief application has become filtration of wastewater.

Lime Dosers are used where adding hydrated lime (calcium hydroxide) causes a chemical reaction which releases water which can be separated by a screw press.  Orange peel, potato peel, and tomato waste are typical examples.

All of this equipment is available in the Vincent Rental Fleet.

Vincent started in 1931 by building a Drum Dryer.  These were discontinued in 2007.

December 2, 2013      

Series KP Presses

October 7, 1996, Revised October 2002                                                                                                                                                                    ISSUE #51

Vincent Corporation has introduced a new series of screw presses. These have been designed to serve two applications where light dewatering is required. In both applications free water is removed more thoroughly than can be achieved with conventional screening devices.

The broadest market for the KP presses is waste from canneries and food processing plants. In these facilities waste is normally sluiced to a collection pit from which it is pumped with a chopper pump. Static and vibratory screens are generally used to strain the waste water from the solids. The solids are then transported to landfills, or given to farmers for animal feed or landspreading.

The problem with this system is that water continues to drain from the solids after the screening. This results in dripping in the parking lot, citations for leaking wastewater on the highway, and loads that are rejected at the landfill because of excessive moisture content.

A conventional screw press is not suitable for dewatering this waste both because the cost of the press is excessive and because the press loses capacity and forces excessive solids into the wastewater stream.

The KP press, with three stages of compression instead of five, addresses these problems. It dewaters far better than a screen, yet it drives less suspended solids into the press liquor than a conventional press. Waste streams that have been successfully tested to date include: cull tomatoes, potato peel from peelers, egg shells at an egg breaker, spent brewers grain, trim material at a facility producing TV dinners, and out-of-date produce at a vegetable and fruit warehouse. One unusual application in this category involves pressing dairy manure to reduce load on the waste treatment lagoon.

The second market for the KP presses is in place of a screen ahead of a conventional screw press. This screening allows conventional presses to press tighter, with higher throughput capacities. It is expected that the KP press will be a significant improvement in this process.

Two applications where the KP press is used ahead of conventional presses are being tested: (1) thickening pumped corn waste materials at wet corn milling plants, and (2) thickening shredded citrus peel in plants that pump the peel to the feedmill. In describing the application we are referring to the KP as a pre-press, suitable for pre-thickening. In essence we are offering double pressing at a bargain capital cost.

The cost of manufacturing a KP press is approximately half of that of a comparable Model VP or CP press. Costs were reduced through a combination of several unique features:

The inlet hopper was simplified, eliminating the inlet screen.

The thrust bearing was eliminated by selecting gearboxes with suitable thrust carrying capacity.

The discharge cone was replaced with a simple discharge plate actuated by a 4-bar mechanism.

The screen covers, spreader bar, and collection pan were replaced with either a single piece of pipe or a pan and cover.

The press does not have a base frame; prior to operating the press the customer must anchor it to steelwork or other suitable foundation.

The value of the KP presses must not be underestimated. The construction is entirely of stainless steel; drive motors have half again the anticipated horsepower requirement, and the gearboxes have been selected for a twenty-year life expectancy.

Shredders Design

June 7, 2012
 

Vincent offers two series of shredders, the traditional Series VS (Vincent Shredder) and the newer Series VCS (Vincent Comb Shredder).

Not many years ago we found that the shredders work better if the blades are 180 degrees apart instead of 90 degrees.  We made them 90 degrees for decades, thinking they would be better balanced.  However, it turns out that balance is not affected.  What does happen is that capacity goes up because there is a longer interval between blades swinging past the inlet, so material falls deeper into the shredder before it is hit by an oncoming blade. 

Today we make all our shredders with blades 180 degrees apart.  Discussion with Corenco, a shredder specialist company, gave us the confidence to make this change.

On the larger 18" models we use one expansion pillow block bearing and one non-expansion pillow block bearing to support the rotor.  The non-expansion bearing goes in the inboard position, closest to the coupling.    The rotor does not expand from heat, but it can move from shock and distortion.  So we lock one end of the rotor and let the other float.

The 18" shredders use Dodge ParaFlex couplings between the motor and rotor.  This keeps shock from the rotor from being transmitted to the motor.  The ParaFlex is like the tire of a small car.  One rim is clamped to the rotor shaft and the other rim is clamped to the motor shaft.  These are rather expensive, but they are the best coupling for the application.

The inlet hopper of the shredders used to be the width of the rotor by one half of the diameter of the rotor.  That is, it was a rectangle located over one half of the rotor.  The idea was that the rotor would turn so that the material, which all fell on one side of the rotor, would be thrown down toward the discharge of the shredder.

Ironically, we had some models where we ran the rotor in reverse, so that the tendency was to throw most of the material up and out of the shredder.  This arrangement suited certain applications.

About ten years ago we found out that it works fine if there is a square inlet to the shredder, measuring the width of the rotor by the diameter of the rotor.  This design does tend to throw material up and out of the shredder, so we always expect that there will be something to stop this material from flying out.  This "something" would be the cover over a screw conveyor which carries material to the shredder, or a dog-leg chute over the inlet to the shredder.

This square inlet is less expensive to manufacture.  Also, it eliminates the job of removing a worn rotor from the shredder and turning it 180 degrees around.  People used to do this in order to use the other (non-worn) edges of the rotor hammers.  Now, when the teeth are worn on one side, it is necessary only to switch two of the electrical leads going to the motor, reversing the direction of rotation.  A Florida engineer, David Tegreene, was the first to come up with this.

It was common practice to put metal traps on the side of the shredder housing.  These would fill up with the material being shredded, which was soft material.  When a piece of tramp metal or a rock came along, the idea was that it would be thrown into the trap or pocket on the side of the housing.  This tramp material would imbed itself there, to be removed periodically.  Today we generally do not bother putting these traps on our shredders.

Note that with the original rectangular inlet, there was need for a trap on only one side.  With the square inlet, two traps were needed since the machine could be operated with the shredder going in either direction of rotation.

The 18" diameter shredders with direct coupled motors run at 1800 or 1500 rpm.  The smaller 12" and 8" shredders run at 3600 or 3000 rpm.  We have also built a lot of shredders with belt drives between the motor and the rotor.  Today we use the direct coupled motor since it is less expensive to build.  An advantage of the belt drive was that it provided a safety factor in the event that the rotor jammed while the shredder was in operation.

Most VCS comb shredders operate without the comb being used.  This is because the main trouble with the comb shredder occurs when a piece of heavy tramp metal enters the machine.  The rotor will jam and stop so suddenly that inertia of the rotor will break the cast iron housings of the pillow block support bearings.  We have found that the VCS shredders work well, in many applications, without the comb.  They do an adequate job of breaking up material so that it will effectively pass into a screw press.

There are some shredders or hammer mills built where the hammers are held by a single pin between two plates.  These hammers can pivot when they hit the material being shredded.  Vincent never did this.  All of our shredders have had hammers or blades that are rigidly mounted to the shaft.  This rigidity was achieved by either using two pins between parallel plates to hold the blades or by welding or keying the blades to a shaft.  Today we almost always use keyways to hold the blades to the shaft. 

Where the blades were welded to the shaft, the construction consists of a tube which is slipped over the shaft.  The blades are welded to this tube.  The tube shrinks from the welding operation, firmly gripping the shaft.  In this manner stress risers, from the welding, are avoided in the shaft.

Vincent makes blades or hammers out of a 410 series stainless.  This alloy is used because it can be hardened by heat treating.

Issue 246

Static Screens

May 2, 1997; Update: August 2013

We cannot name another industrial product that goes by so many different names.  Static Screens are known as Sidehill Screens in the pulp and paper industry and on the dairy farm.  The same devises are commonly referred to as Gravity Screens, Slope Screens, and Inclined Screens.  Sometimes they go by trade names:  Hydrasieves, DSM’s, and Hydradensers.  Dr. Ashley Vincent called them Catenary Screens, after the shape that a chain takes when it is hung from two points (although the screens generally have either a flat or a circular profile).

The device we are referring to consists of liquid reservoir at the top, a weir (or dam) over which liquid flows, and a sloped screen which allows filtered liquid to flow through while suspended solids are being separated.  The solids, known as tailings, fall off the lower end of the screen.  A chief advantage of these screens is that they have no moving parts.

Vincent Corporation builds static screens because they can be used to thicken a dilute flow ahead of our screw presses.  For example, if a facility has a dilute flow with only 1% to 2% solids, it may take a large press to handle the volume of liquid involved.  If instead the facility thickens the flow to 4% or 6% solids by running it over a static screen, then a press one or two sizes smaller than otherwise required will be able to handle the job.  The combination of the static screen along with the smaller press will cost less than the single larger press.  In addition, the press with a sidehill is better prepared to handle upsets, start-ups, and other abnormal conditions.

A second use for a static screen is to filter the press liquor produced by the press.  In all press applications there is some fiber forced through the screen into the press liquor.  If the presence of this fiber is objectionable, the press liquor can be filtered with a static screen which is mounted over the inlet to the screw press.  That way the fiber that made it through the screen is fed back into the press, to be captured in the press cake on its second pass.  This arrangement does create a circulating load of fiber in the press liquor; however, it is only very rarely a problem.

Static screens are sold in standard widths: 1-1/2', 3', 4', 5', and 6'.  We generally think of them as having capacities of 50 to 150 gpm per foot of width.  This figure works on press liquor flows found in citrus processing plants.  In paper mill applications, figures of 300 to 600 gpm per foot can be used with low concentration "high freeness" flows.                                       

Another option available in static screens is the slot width of the wedgewire.  The most common specifications are 0.020” and 0.030”.  The finer the slot, the finer the filtration. This is offset by capacity reduction and a propensity to blind with the finer slot width.

When the solids in the liquid flow have a tendency to blind the screen, a spray bar accessory can be supplied.  The spray bar is a network of pipes and nozzles.  It is used to periodically spray the face of the screen with water.  Sometimes a timer is used to automate the process.

Traditionally static screens have a long surface, 6' being typical.  Vincent also offers an economy line of statics screens.  These have screen panels which are only 30" long.

Issue 60

 

 

 

 

Steam Injection

July 5, 2002                                                                                                                                                                                                         ISSUE #129

Up until the Oil Embargo of the early 1970's it was common practice to inject steam into screw presses. The steam was injected directly, through hollow resistor teeth, into the material being pressed. This was done to reduce the moisture content of orange peel that was being made into cattle feed. The practice seems to have been abandoned for two reasons: the high cost of steam energy, and the fact that most citrus feedmills lacked the Waste Heat Evaporator capacity to dispose of all the press liquor being produced.

Driven by the need to reduce VOC (Volatile Organic Compound) emissions, interest has resumed in pressing as much liquid as possible from citrus waste. One solution has been to use high pressure, high horsepower screw presses. To evaluate an alternative, Vincent Corporation acquired a boiler and conducted tests with live steam injection.

Initially we were cool to the idea of using steam. We reasoned that it would be more efficient to evaporate moisture with a direct fired rotary drum dryer. However a California research firm, Altex Technologies, brought to our attention that steam addition in a press will drive out liquid water, whereas a drum dryer removes the moisture in the form of water vapor.

The difference is very important: by pressing out liquid water, there is a savings of about 1,000 BTU's per pound of water. This is because the drum dryer requires this energy to convert the water from the liquid to vapor state.

To prove the concept, a basic test was conducted. Drums of peel were brought to the Tampa works from two local feedmills. This peel had been reacted with lime and single pressed. The peel was collected at the inlets to rotary drum dryers. The samples from both feedmills had a respectable 18º Brix. However the moisture contents of both samples were high, 71% to 73%, because of special conditions existing when the peel was collected.

This cake was second pressed in a laboratory screw press in Tampa. Probably because of a delay of a few hours that occurred after the samples were collected, the resulting press cake was reduced (consistently) to about 59% moisture. Part of this moisture reduction was due to using the press electrical drive to heat the peel: cake temperature increased by 10° F to 15° F while passing though the press.

Addition of steam, at various flow rates and at pressures up to 45 psi, significantly improved the press cake moisture that could be achieved. Final moisture contents of 55% to 57% resulted. In the process the temperature of the discharge cake and liquor was increased to about 160° F.

Most importantly, the extra moisture separated by the screw press came out as a liquid, not as vapor. Therefore the old steam injection technology appears worthy of further investigation. We hope to participate in full scale testing during the next citrus season.

Twin Screw Citrosuco Report

March 15, 2001                                                                                                                                                                                                     ISSUE #101

Last season a series of citrus feedmill tests were run with the Twin Screw Press prototype. Both limed and unlimed peel were pressed. The report, updated with reference to more recent non-citrus testing, follows:

The test goal was to determine the operating characteristics of the Vincent twin screw design. This was needed in order to establish the design specifications and performance capacities of larger machines.

The performance of the prototype machine met our designers' highest expectations. The areas studied were:

Feeding Characteristics 
Without any qualification, the way material feeds into the twin screw press is the best ever observed in any screw press. Feeding is normally not a problem with limed peel. However, a great deal of slippage occurs with materials like un-limed (fresh) peel. Normally Vincent de-rates press capacity by 70% with un-limed peel. When raw FMC peel straight from the peel bin was run, it was found that a de-rating of only 25% was necessary. This strong feeding characteristic has been confirmed on raw fish and spent brewers grain, both of which are also slippery materials.

(A consequence of this is that the press Supercharger, so many years in development, has been obsoleted.)

Throughput Capacity 
A goal was to measure the capacity of the twin screw press against a known machine. Since the test machine has twin 6" screws, it was compared it to the single screw Model VP-6. Vincent has almost 40 years of experience with the VP-6, and the VP-6 screw configuration was used in the twin screw prototype. It was found that, in seven tests with the Model TSP-6, the capacity averaged 254% of that of the single screw VP-6. (At half speed, 30 Hz, this was 174%.) This allows Vincent to guarantee that the throughput capacity of a twin screw press will be double that of a single screw press with the same screw diameter.

Press Cake Moisture 
It was found that the twin screw press has excellent dewatering characteristics. In all moisture tests it was found that the twin screw press removed as much, or a little more, water than the other presses in the feedmill.

The press cake moisture data from four tests follow:

  Test #1 Test #3 Test #2A Test #4
Twin Screw Press 66.5% 64.5% 64.9% 67.0%
Gulf Press #2 67.1% 68.5% 68.6% 67.1%
Vincent VP-22
(with cone withdrawn)
67.9%   71.1% 70.0%

Final press cake moisture is determined by considerations beyond the screw press: the Brix and quantity of molasses added, the amount of waste water present, and the completeness of the lime reaction.

Based on June testing in Mexico on a special VP-22, it has been concluded that it will be best to have seven stages of compression in the press. (The test machine has five.) This will extend the slightly better 30 Hz performance to a 60 Hz machine. It also will give latitude for achieving maximum moisture removal over a wider range of operating conditions (wet peel, underlimed peel, old peel, a worn press, etc.).

It should be noted that the twin screw press is bound by the same laws of chemistry as other presses. A mechanical machine can remove only the free and interstitial water from vegetable material. To remove the hydrogen bound water and the chemically bound water it is necessary to apply heat. This is normally done with combustion energy in a dryer. It also can be done in a screw press by using the drive motor to cause friction heating of material being pressed. The Vincent Twin Screw Press stops short of dewatering by this inefficient use of electrical energy.

Horsepower Requirement 
It was noted that the twin screw press does not draw as much power as was anticipated. The prototype drew under five horsepower in all citrus testing. This has held true for spent brewers grain, raw fish, and carrot pulp. Only with shrimp shells has there been a need for the full power of the 7-1/2 motor used on the test machine. The lower than expected horsepower requirement is attributed to the slicing action of the overlapping interrupted screw flights.

Susceptibility to Damage from Tramp Iron 
During testing and operating four serious incidents of tramp material entering the prototype press have been recorded to date. The items found were a piece of a pump impeller, two valves (one brass, one steel), and a piece of screw conveyor flighting. These were large pieces of metal compared to the diameter and flight thickness of the screw.

The extent of screw and resistor bar damage that occurred was comparable to what is normally experienced in a single screw press, and the damage was very easily repaired in all four cases. It is notable that no appreciable damage to the profile bar screen occurred in any of the four cases.

However it was apparent that a large piece of tramp material will damage more parts inside the twin screw press because of the overlapping screws and the larger number of resistor teeth. For this reason special attention is being given to electrical and mechanical overload conditions.

During the testing observations were made of a number of other areas. Among these were vibration, rigidity, sufficiency of the screen open area, screen deflection and abrasive wear. The prototype design proved quite adequate in all of these.

Overall, Vincent is delighted with the Twin Screw Press. It marks a significant advance in screw press design because the performance is equal or better to anything achieved in the past. In financial terms, it is possible to produce a machine with double the capacity of a single screw press, but at less cost than two single screw presses.

 

 

Twin Screw Press Patent

May 27, 2003                                                                                                                                                                                                       ISSUE #138

Here at Vincent we are proud of the award on April 22, 2003 of United States Patent number 6,550,376. It describes a TWIN SCREW PRESS WITH INTERRUPTED FLIGHTS. The screw press described in this patent was first introduced in the early months of 2000.

Most machinery patents describe minor modifications of existing technology. This is especially true in the case of screw presses because they are extremely mature machines in the historical sense. These patents are referred to as extension patents because, by covering a minor change, they can extend the life of an older, more important, patent.

What is unusual about the new Vincent patent is that it describes an altogether new class of screw presses. The patent starts by describing how Valerius Anderson invented the interrupted flight screw press in the year 1900. At the time, this technology was a major departure from the then traditional continuous flight screw presses. The patent goes on to describe how screw press technology took another step forward with the introduction of the twin screw, continuous flight, screw presses. Both of these classes of screw presses have unique advantages and weaknesses.

The just-issued patent describes a new class of screw presses that combines the advantages of the two earlier classes. Technically, the invention features (1) the high capacity and low horsepower (relative to size) of the interrupted screw press, and (2) the strong, positive throughput and dewatering features of the twin screw, continuous flight, press.

The patent makes reference to a number of earlier patents. Among these is US Patent number 647,354, the original 1900 Anderson patent. The number assigned to the new patent, 6,550,376, indicates that almost 6,000,000 patents have been issued in the intervening 103 years.

Vincent Corporation is enjoying technical success with the Series TSP Twin Screw Press machines. Small models have been supplied to shrimp waste processors in four different countries. Other units have proven successful in dewatering both limed and washed citrus peel, juicing pineapples, dewatering spent brewers grain, separating oil and water from raw fish, and, most recently, extracting starch from raw potatoes.

A copy of the patent is available upon request.

Vapor Tight Model VP-24 Press

February 7th, 2006

The Series VP ("Vincent Press") screw presses came out in 1952. The latest addition to this series is the Model VP-24. This machine is for applications were the Model VP-22 is borderline in capacity. The VP-22, introduced in 1973, was to have double the capacity of a Model VP-16. Over the years we have found that it generally falls short of this mark. In contrast, the VP-24 is expected to easily double the capacity of a VP-16.

The attached photo shows the first VP-24 that we have produced. This machine was done in vapor tight construction because it will be used to expel aqueous alcohol solution from citrus pectin. The machine is being installed in the Danisco plant in Mexico.

A second VP-24 is expected to ship to China later this month. It, too, has the vapor-tight design as it will be used to separate alcohol solution from apple pectin. The drives of these two machines differ because the applications are different: the Danisco machine is 40 horsepower, while Yantai Andre Pectin requires only 20 hp.

Both presses will be driven by VFD's. The Baldor explosion-proof motors that were selected are rated for operation from 9 to 90 Hertz.

The discharge cone of the VP-24 is actuated by dual air cylinders. This simplification is now appearing in almost all Series VP presses. It is especially good in vapor-tight applications as it puts the air cylinders and thrust bearing outside of the vapor-tight compartment.

The design of the covers on these presses has been improved as a result of work with CP Kelco in Denmark. There is a 1/2" O-ring of solid Silicone mounted in a pocket that follows the perimeter of the cover. The cover itself is a thick honey-comb structure that minimizes warpage. This simple design provides reliable sealing while greatly reducing the number of clamps required.

Vapor-tight presses must use direct coupled drives to avoid the fire hazard associated with belt drives. Direct-coupling is used in many other applications where the length of the machine is not an issue. A belt drive allows shortening the machine by approximately the length of the motor.

A much-simplified mechanism is being used to drive the discharge cone when the rotating cone feature is specified. This has greatly reduced the cost of this option.

Issue 170

Vapor Tight Screw Presses

February 18, 2002                                                                                                                                                                                                ISSUE #125

Recently a very successful start-up of two Model VP-22 screw presses was accomplished. These machines are unusual in that they were made in vapor tight construction. The presses are being used to separate aqueous alcohol solution from pectin.

The customer is CP Kelco, formerly Copenhagen Pectin. Their factory in Denmark is the world's largest producer of pectin, a food ingredient which is extracted from dried citrus peel. The raw material, dried lime, lemon, grapefruit, and orange peel, is purchased from citrus processors around the world.

The pectin is extracted from the peel with acid followed by isopropyl alcohol (IPA) precipitation. The product goes through various wash stages before final pressing ahead of drying. Vapor tight covers contain the IPA fumes, which can be explosive.

Currently Vincent has another vapor tight press under construction. It is a VP-16 that will be used in the production of Soybean Protein Concentrate (SPC). This is a traditional application for Vincent screw presses. In the process aqueous ethanol is pressed from the soybean protein ahead of a steam dryer. The installation will be in Haifa, Israel, with start-up scheduled for later this year. (See Pressing News #24, Solvent Extraction.)

Another machine, a CP-6, is being designed for Crown Iron Works of Minneapolis. This press is proposed to be used to separate methanol solution from a material similar to pine needles. This installation will be on Prince Eduard Island, Canada.

The machines reflect safety concerns because of the alcohols that are present. Explosion proof motors are supplied. Another feature is the use of bronze fasteners to prevent sparking. Because of the potential for fire, V-belt drives cannot be used, so in-line drives are necessary. Bolted vapor tight covers are used throughout, usually with Pyrex portholes that include manually operated wipers. These design features assure compliance with safety codes.