Section IVSection IVFeeding Technology and Product Feeding Technology and Product

OverviewOverview

Lucas Frei

Regional Sales Manager Ukraine

Why are Feeders Necessary?To set the precise throughput to a downstream process

Continuous processes such as mixing or extrusion become “slaves” to the feeders

Provide an accurate blend of bulk solids and liquids for a formulation

Eliminate pre-mixing of solids/segregationUsing individual feeders for each component of the blend

Feeders are used to set the flow rates of both liquids and bulk solids.

Volumetric FeedingVolumetric Feeding

Volumetric Feeding I

Speed Regulated Volumetric Feeding:

Speed

Setpoint

Motor Drive

Gravimetric FeedingGravimetric Feeding

Gravimetric Control Principle

Weight signal

Controller

Speed

Setpoint

Gravimetric FeedingGravimetric FeedingLoss-in-Weight FeedingLoss-in-Weight Feeding

Loss-in-Weight Principle

G

G2

G1

t2 t1

t

G

t

G = G2 - G 1 t = t2 - t1

Refill Levels

Refillstarts

Refillstops

Important Refill Considerations

Choosing the Proper Refill Device

Reaction Time of the DeviceDevice must be LEAK FREEMaterial characteristics

Choosing the Proper Hopper Size for RefillChoosing the Refill TimesDefining importance of accuracy during refill, particularly when low rate feeding

Bellows

Venting

Ventingwith filter bag

Central venting

Feeding ModesThere are two basic feeding modes:

BatchGain-in-weight batch

Loss-in-weight batch

Continuous

GIW Batching via Volumetric Feeders

Volumetric feeders dose bulk material into a weigh hopper

Increase in collection hopper weight is measured

Scale’s weight info is used to control each feeder based upon setpoint or recipe

volumetric feeders

hopper on load cells

Gain-in-Weight Batch

Gain-in-weight batch operation in slow motion

Gain-in-Weight Batch SystemsAdvantages

Only one scale device for load hopper

Cost effective since feeders are volumetric

Well suited to large batches

DisadvantagesTotal batch time is dependent upon the number of individual batch times necessary

Combination of large single batches and very small batches not as versatile (due to large taring values of the collection hopper)

Loss-in-Weight Batch PrincipleLoss-in-weight feeders dose bulk material into a collection hopper

loss-in-weight feeders collection hopper

Click for LIW Batch video

Loss-in-Weight Batch SystemsAdvantages

Each ingredient is batched out in its own LIW feeder

Feeders can then operate simultaneously, making overall batching process shorter

Can also batch out variety of ingredients at different bulk densities and high variation in mix percentages with high accuracy

Used for minor and micro ingredient weighing where individual percentages and accuracies required are outside the realm of GIW or scaling applications (0.5% of full load )

DisadvantagesHigher initial investment for loss-in-weight feeders

Continuous Feeding

Benefits:

• Online recipe control

• No premix station required

• No product segregation

• Shorter residence time

• No waste of premix

Feeding TypesFeeding Types

Typical Feeders Used in Processing

Weigh belt feeders

Rotary Valves

Vibratory trayVolumetric

Gravimetric/Loss In Weight

Screw Types – twin and

single screwVolumetric

Gravimetric/Loss-in-Weight

Microfeeding

Belt Speed

Belt Tare Weight

Material & Belt Weight

DriveCommand

Operation:Material is conveyed along a belt

Belt is suspended on weigh bridges

Belt load is measured, belt speed then calculated by control unit

Weigh Belt Feeding

Weigh Belt Feeder Benefits

Low cost for high volumes of flow

Function easy to understand

Compact for high flow rates

Can be extended to use as a conveyor

Handle large particle size bulk material

Low power requirements

Works well in difficult environments

Rotary Valves Operation:

• Series of pockets delivers material volumetrically to process

Advantages:• Simple design – good for free

flowing materials• Can be designed for explosion

containmentDisadvantages:

• Not ideal for packing/cohesive materials• No good control on product delivery, i.e. pocket fill

may vary• Difficult to manage and clean• Pulsating Discharge • Limited turndown capabilities

Vibratory Feeders Operation:

Material is conveyed by vibration

Can be volumetric or gravimetric

Advantages:

Simple design – good for free flowing materials

Can also be good for difficult flow materials - high aspect ratio

Gentle on products where attrition may be an issue

Disadvantages:

Not ideal for packing/cohesive materials

No good control on product delivery, ie LUMPS IN TRAY

Limited turndown capabilities

Unique Drive Technology

Quick and precise control due to displacement feedback

Resonance tracking allows different configurations without adjustment

Strong vibration motor with four air gaps

Enhanced LWF Algorithm improves accuracy

N(S)

S(N)

N(S)

N S

Magnet

Coil

Tray

Shock mountsSpring

FeedbackSensor

Screw Feeders Operation:

Material conveyed by either single or double screwCan be volumetric or gravimetric

Advantages:Twin screws can be good for cohesive materials Accurate delivery of product

Disadvantages:Design options are critical with regards to overall cleanability

Single Screw vs Twin Screw

Single Screw ideal for free flowing materials, high volumes

Twin Screw ideal for more cohesive materials

Twin screws have a “self wiping” effect

Twin screws can also provide more even flow to the process

Microfeeding as defined by K-TronMicrofeeding is defined as the ability to feed powders consistently and in a dynamic method to a process, at rates as low as 20 gram/hour*

Can be provided in either volumetric or gravimetric design, with gravimetric resulting in highest accuracies at low rates

Can also be provided for batch or continuous feeding

• It has been used in limited cases as a doser, but it is not recommended for constant on/off operation

* Reminder: 20 g/h = 0.33 g/min

feedrate1% 2sigma dev. (60s) = 3.3

milligram/min

Gravimetric FeedingGravimetric FeedingWeigh Belt FeedingWeigh Belt Feeding

WBF Control Loop

Controller

Setpoint

Speed

Weight signal

WBF Control Principle I

Single scale version

q Q = q v*

speed p ick-up

Speed feedback (v)

W eigh bridge

M ass flow

Setpoint

Contro llerM otor driveDrive com m and

Contro ller

Belt load (q)

WBF Control Priniciple II

Twin scale version

Q = q v*q

speed p ick-up

Tare

Shiftreg iste r

B ru tto N etto

Speed feedback (v)

W eigh bridges

M ass flow

Setpo in t

C ontro lle r

M otor drive

Drive

com

man

d

C ontro lle r

Belt load (q)

Gravimetric FeedingGravimetric FeedingFlow MeteringFlow Metering

Smart Flow MeterUnique design features:• continually free path

• gentle handling of bulk material

• easy to clean

• no energy needed to transportbulk material

• practically maintenance free

• independent of bulk material

• integrated autotare system

• no moving parts

• simple, robust design

Measuring Force FR

The resulting force FR

is measured by the upper sensor station.

FR

Measuring Force FP

The resulting force FP is measured by the lower

sensor station

FP

Taring at the touch of a button

The K-SFM can easily be tared at any time by diverting the flow of material through the bypass.

SFM VIDEO

Bulk Solids Pump:a New Approach Bulk Solids Pump:a New Approach To Solids FeedingTo Solids Feeding

Feeding Concepts

Definition of a Bulk Solids FeederA method of bulk solid flow control based on the correlation between machine speed and discharge rate.

Typical conveying systems are:

Screw feeder

Belt feeder

Rotary feeder

Vibratory feeder

M

M

BSP Technology

Ideal Feeder Characteristics:Ideal Feeder Characteristics:• Gentle Product Handling• True Positive Displacement Action• Absolutely Linear Over Full Operating Range• Excellent Uniformity of Discharge• 100% Active Discharge (minimal residual material)• Able to Handle Differential Pressures• Low Maintenance Design• High Wear Resistance• Low Power Consumption• Quick and Easy to Clean

Feature Screw Feeder Belt FeederRotary Feeder

Vibratory Feeder BSP

True positive displacement action

No Dependent on material

No No Yes

Linear over full operating range

Poor(dep. on screw fill)

Dependent on material

Poor No yes

Uniformity of discharge Poor(pulses)

Dependent on material

Poor(pulses)

Good Good

Active discharge (no residual material)

limited(product build-up

in screw flight)

limited (product build-up on belt)

Bad(product build-up on the rotary wall)

Bad Good

Unaffected by differential pressures

Limited No Yes No Yes

Mechanical & maintenance simplicity

Yes No Yes Yes Yes

Wear Resistance Poor Poor Poor Good Very good

Power Consumption High Medium High Low Low

Product Degradation High Medium High Low Very low

Comparison of Feeding Concepts

Lock-Up Principle

The BSP principle provides continuous, positive The BSP principle provides continuous, positive displacement volumetric control by exploiting displacement volumetric control by exploiting the phenomenon known as lock-upthe phenomenon known as lock-up..

LOCK-UP

BSP Video Clip

click on the graphic to start the video

Liquid FeedersLiquid Feeders

Feeding Liquids

Depending on the application and accuracy required, two feeding modes are possible:

Volumetric Loss-in-weight

M

PID Control Principle

controller

setpoint

motor drivecurrent

thoughput feedback

DCmotor

pump flow meter

drivecommand

Design

The liquid tank is mounted on either 3 SFT‘s or a scale

Flexible connections to the pump which is independent of the weigh system

The controls are standard K-Tron loss-in-weight controls

K-TRONK-TRONWeighing TechnologyWeighing Technology

The Principle

The K-SFT supplies a fully compensated true weigh signal.

* ASIC: Application Specific Integrated Circuit

Fo rc e

vib ra ting wire

te m p e ra turese nso r

p o we r sup p ly

RS 485se ria linte rfa c e

e le c tro nice xc ite r

te m p e ra turec o nve rte r

we ig ht p ro c e sso rm ic ro p ro c e sso rc a lib ra tio n EEPRO M

SFT FeaturesOne-time only calibration by manufacturer

Integrated linearization and temperature compensation

High accuracy and reliability in any environment

Fast sampling time- 112 samples per second

1: 4`000`000 resolution in 80ms

Improved filtering techniques- real time calculation- not just sample averaging

Simultaneous sampling/processing

Improved Performance

10 20 30 40 50 60 70 80 90 100

10 20 30 40 50 60 70 80 90 100

5040302010

0-10-20-30-40-50

We

ight

(g

)

100

-10

We

ight

(g

) 2030

-20-30

Frequency (Hz)0

Conventional Weighing Technology

Frequency (Hz)0

K-Tron SFT II Output With Digital Filtering

Accuracy

ActiFlowActiFlow

Prevention of bridge building with difficult flowing materials

Hoppers & Agitation

AC Agitator Drive

Vertical Agitator

Horizontal Agitator

Vertical Agitation

Requires additional headroom above the feeder

Heavy motor on lid can make servicing difficult

Needs a separate motor starter (DOL)

Causes clean-ability issues.

Expensive

Poor Flow in Hoppers = Poor consistent feeding

Difficult powders:May get compacted

Form ratholes & bridges

Result in operation:Production interruption

Quality problems

Screw feeder accuracy is a function of consistent screw fill

Ratholes or bridges

Alternative Solutions for Improved Hopper Flow

Design Options

Vertical Agitation

Flexible Elastomer Liners

(eg FlexWall, Shear Hoppers)

Bin Vibrators

Air Injectors (eg Magic Mushrooms)

Elastomer Coatings

Hopper Flow Aids – Pros and ConsOPTION PROS CONS

Vertical Agitators

May be better suited for Large Hoppers

Require additional headroom for operation and maintenanceCan cause weight disturbances in gravimetric feedersCleanability and accessability are concerns

Flexible Liners Keeps material fluid in hopper

Can cause additional packing and densification of cohesive materialsLiners can stain =cleanability concernCan cause weight disturbances

Bin Vibrators External to process Can cause additional packing of materialCan cause weight disturbances depending onfrequencies

Flow Aid for LIW feeders - ActiFlow

KCM

CA UTION - Disconnec t po wer be fore opening.115/230VAC 50/60 HZ, 2000Watts (M ax)

ActiFlowCONTROL

CAUTION - Disconnec t po wer bef ore opening.115/230VAC 50/60 HZ, 2000Watts (M ax)

Serial Weight Channel

Motor Power / Speed Pickup

Coil Power / Position Feedback

ActiFlowControl Unit

ActiFlowDevice

KCM

ExtensionHopper

WeighingSystem

Feeder

Click for Actiflow video

ActiFlow Design

The ActiFlow Device is bolted to the outside of the hopper wall, with no product contact. It is ideal for applications which require a stainless steel hopper.

The special design ensures material activation has a minimal effect on the weighing system.

Questions?