section iv feeding technology and product overview lucas frei regional sales manager ukraine
Post on 26-Mar-2015
225 Views
Preview:
TRANSCRIPT
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?
top related