Training - Level

L ev el 1 - Fu n d am en t al Tr ai n i n g

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Level 1 Fundamental Fundamental Traini Training ng

1

Level Level 1 - Level Level

Contents

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To p i c s :

Sl i d e No :

• Wh y m eas u r e l ev el ?

3-5

• L ev el t er m i n o l o g y

6 - 19

• Tec h n o l o g y s el ec t i o n

20 - 29

• Tec h n o l o g y (Pr es s u r e

30 - 55

Transmitter, HTG & Hybrid System • Other ther Te Technolo chnology gy (Float, loat, Capacita pacitance nce,,

56 - 75

Displacer, Servo, Nucleonic, Laser & Ultrasound) • Ex er c i s e

76 - 80


Power Point Presentation Presentation Handou Handou ts


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Why measure level? 5 Commo C ommo n Reason Rea son s Common Reasons

3

Inventory •

keep track track of amount amount of of material material of of material material availabl available e for a process process

Custody Transfer Transfer •

amount amount of materia materiall that is is bought bought & sold sold in terms terms of volume volume or or weight weight

Effieciency •

maxi maximi mise se stor storag age e tank tank capa capacit city y

•

preventing preventing unnecessar unnecessary y expense expense of purcha purchasing sing additio additional nal vessels vessels

Safety •

prev preven entt spil spillag lage e in open open ves vesse sels ls

•

prevent prevent overpres overpressure sure conditions conditions in closed vessels vessels that that may result in rupture

Consistent Supply •

to maint maintain ain produc productt quali quality ty in a proce process ss » blending, pulp & paper Level Level 1 - Level Level

Why measure level? Inventory vs. Process Inventory

4

Inventory • Accu Ac cu racy rac y is i s pri p ri mary mar y dif d iffer ferenc enc e » better better than than 3 mm precisio precision n needed needed • Appl Ap pl icati ic ation on s need n eed prec p rec ise is e measur meas ur ement emen t becau b ecau se of o f $$$$$ $$$$$ » Transf Transfer er of of owner ownershi ship p » Exact Exact quanti quantity ty must must be known known » Prod Produc uctt cost cost » Tend Tend to be large largerr vesse vessels ls

Process • Appl Ap pl icati ic ation on s are ar e more mo re con c on cer ned with wi th : » Control Control of a product product level level within within a range range

You can have a mixture of process and inventory applications in a plant

» Safety Safety (prevent (prevent overflow overflow// pump shutof shutoff) f) » Monitor Monitor inputs inputs of component components s of a process process » Accuracy Accuracy require requirement ments s vary vary widely widely Level Level 1 - Level Level



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Why measure level? Indication vs. Control

5

Indication • on-site level check • operator in terpret measurement measurement  Indicators

– open loop control system – help calibrate automatic control system Control • closed loop system  process ;

point of measure ; transmitter ; controller ; control valve ; process


Level Level terminolog y Level Control Loo Loopp Level Control

6

(Inflow) I/P

L IC

• Level Loop Issues: – Control At Inflow Inflow or Outflow – Non-Self Regulating

LT




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Level Level terminolog y Level Control Loo Loopp Level Control

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(Outflow)

LIC

I/P

LT


Level Level terminolog y Parameters

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Interface Level

Volume Density

Mass Level Level 1 - Level Level



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Interface • Interface Interface measurement measurement find s the boun dary between between two liqu ids sto red in the same tank tank » each liquid has different different density

Liquid Liquid A to air/vapor air/vapor interface interface Liquid A Liquid A to B interface Liquid B



10

Density Density is a measure measure of th e mass per volume • Density Example: – grams / cc – pounds / cu ft • Specific Specific Gravity Gravity is a ratio of the density of a Density fluid to the density of water, water, thus density of fluid

= SG

density of water Density of fluid = density of water * SG

Mass Mass = Density / Volume Level Level 1 - Level Level



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Volume relates directly to level level when: • Volume only cor relates » Tank is is an uprigh uprightt cylinde cylinder r » Density Density is constant constant Volume

» Temperat Temperature ure is is constan constantt

» There is no change in tank wall wall position after filling • Volume measurements measurements are in units such as: » gallons gallons,, liters, liters, barrels. barrels... .. • Level Level measurements are in units such as: » inches, feet, millimeters, millimeters, centimeters centimeters,, meters... meters... • Correlation Correlation o f volu me to level level varies with geometry of tank and may be expressed expressed in t erms such as: » gal/inch gal/inch,, liters/m liters/meter eter,, barrels barrels/inc /inch... h... Level Level 1 - Level Level


12

r

Volume • Vertical Cylindrical Tank » v=

h

l

2 πr l

h

• Horizontal Horizontal Cylindrical

r l

» v = πr 2atan[l ½/(2r-l)½]+h(l-r)[l(2r-l)]½

• Sphere Tank » v = πl2(3r-l)/3

r l




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Volume • Horizontal Bullet Tank » v = πr 2/3 * (3r-l) + 2r 2(h-2r) *atan[l ½/(2r-l)½] + (h-r)[l( (h-r)[l(2r 2r - l)]½

h r l r h

Vertic al Bullet Tank • Vertic

l

» v = πr 2/3(3r-l)

if l ≤ r

» v = πr 2/3(3r-l)

if r < l < (h - r)

» v = πr 2(h-2r) + [ π(l+2r-h) 2]/3 * [3r-(l+2r-h)] if (h - r) ≤ l Level Level 1 - Level Level


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Volume • Tanks with Dished Ends » no standard standard shape shape – use strapping tables to determine volume 10

9 7 5 3 1

Point

Level Volume (inches) (inches) (gallons) (gallons)

1 2 3 4 5 6 7 8 9 10

0 5 10 15 20 25 30 35 40 100

0 10 32 68 115 173 230 313 394 957

Bulging A look-up table that relates level to volume for several discrete points in a tank. Commonly used to eliminate Bulging Error.




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Level Level terminolog y Measurement Characteristics

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...a ...and nd th e techno technologies the logies may have to handle a number of application application conditions. conditions. 0

-14.7

PSIG

Steam, Stea Steam, Steam, m,vapors vapors,, dust dust

Ab Abras rasivivee fluids fluids

Foam Foam

Density Changes

High High vacuum vacuum

Corrosive Corrosive processes processes

Viscous Viscous or or sticky stickyfluids fluids

Temperature Temperature extremes extremes

Ag Agititati ation on


Level Level terminolog y Measurement Characteristics Bottom-Up vs. Top-Down Measurement

16

Top-down

Top-Down Measurement • Poses less potential for leakage • devices installed or removed without emptying tank  e.g.,

dipstick, radar gauge

Bottom-Up Measurement • Typically contacts the process fluid e.g.,  e.g.,

pressure tr ansmitter, weigh scale

Bottom-up Level Level 1 - Level Level



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Inferred vs. Direct Measurement • An Inferred Inferred measur measuremen ementt is derived derived from from another another measurement Ex: Ex: pressu pressure re trans transmi mitt tter er

Head Pr es s u r e = L ev el

,

Mas s

Den s i t y

= L ev el

Den s i t y

Stability of variables is critical to get a good inferred measurement. If variables are not stable, compensation needs to be made.

• A Direct measurement measurement looks looks only only at the desired desired variable Ex: floats, dipstick Level Level 1 - Level Level


18

Continuous vs. Point Measurement Measurement

Continuous Measurement • Constant detection of

product height • Concerned with amount of product • May May be used to cont rol addition of other compon ents to the vessel vessel

Point measurement • Has the level reached • • • •

this point? High or low level detection Often Often u sed for alarm alarm control May May start or stop pumps May May open or clo se valves




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Non-Contact vs. Non-Invasive vs. Non-Intrusive Non -Contact Contact implies that the device does not touch the fluid, but it could be invasive

Non -invasive implies that the device does not pass the walls of the tank nor touch the process directly

Intrusive Non -intrusive implies that the device may come in contact with the fluid, but does not protrud e into the fluid or interfere with flui d movement Level Level 1 - Level Level

Technolog Technolog y selection selection Level Measurement Measurement Technol ogi es ogies

20

Bubbler Dipstick Capacitance Tuning Fork

Float

Ultrasonic

Radar Sight glass Nuclear

Displacer

Gage Glass

Differential Pressure

Ultrasonic Gap Hydrostatic Weight Level Level 1 - Level Level



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Technolog Technolog y selection selection Classification of Level Measurement Technologies C o nt nt ac ac t in in g N o n co co n ta ta ct ct in in g P o in in t

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C o nt nt in in u o us us L iq iq u id id s S ol ol id id s

Bubblers Capacitance Conductivity Displacers Floats HT G Hydrostatic Laser Magnetostricti Magnet ost ric tive ve Nucleonic Optical Phase Differenc Difference e Radar Resistance Resistance T ape Rotation Rotation Suppres Suppress s ion Serv Servo o Tape Level Thermal Ultrasonic Vibration Weighing Level Level 1 - Level Level

Technolog Technolog y selection selection Classification of Level Measurement Technologies D en en s it it y In te t e rf r f a ce c e L ev e v el el Bubblers Capacitance Displacers Floats HT G Hydrostatic Laser Magnetostrictive Nucleonic Phase Differenc Differenc e Radar Resistanc Resistanc e Tape Servo Tape Level Ultrasonic Weighing

22

M as s

Note: Only continuous devices included




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Technolog Technolog y selection selection Factors To Consider Factors

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• Why is the level measurement needed?  What are are you tr y to measure?  What are you trying to achieve? – Indication – Indication of fluid level – Al Al arm set po in t to t o p rev ent sp il l o ver – Transfer – Transfer (Sale) (Sale) of produc t – Contol – Contol of Product Product Mix Mix – Leak – Leak Detection – Interface – Interface detection

• What What are the condit ions wi thin o r on the vessel?  Product

turbulence  Obstructions  Mounting constraints  An gle gl e of repos rep os e for fo r sol s olid id s  Temperature Temperature and pressure limits Level Level 1 - Level Level


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• What What are the enviro enviro nmental condi tions ?  Ambi Am bi ent

Temperat Temp eratur ur e

 Humidity  Vibration  Electro

Magnetic Interf erence(EMI erence(EMI))  Transient Transient protectio n

• What What are the product c haracterist haracterist ics?  Corrosive  Viscous  Dusty,

Foam  Variable Densit Densit y  Variable Dielectric constant  Tendency to Coat  Interfaces, Interfaces, gradients, suspended solids  Steam Steam or oth er vapors Level Level 1 - Level Level



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Common Density/ Temperature Changes



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Typical Dielectric/ Temperature Changes




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• What What are the instru ment requirements?  Performance

requirements  Location approvals  Power requirements  Output requirements  Number, location, and size of taps  Total costs

– Product – Installation Installation – Maintenance Maintenance


Technolog Technolog y selection selection Performance Performance Consideration

Environmental Factors

Device

28

Temp changes Vibration Noise

Process Density changes Conditions temperature changes

Direct vs inferred Measurement capabilities Rangeability

static pressure agitation aeration foam dielectric changes Level Level 1 - Level Level



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Technolog Technolog y selection selection Working Ca Capabilities pabilities Vary Vary with Te Technolog chnolog ies Technolo chnolo gies 10000+

29

Nucleonic Capacitance

3626 Pressure w/ seals

I S P , e r u 1000 s s e r P

Pressure/HTG

Displacer

Ultrasonic Point

Ultrasonic 73 atm -240

Radar -100 -40

32

195

320

600

400

800

900+

Temperature, o F Approximate values are shown. Pressure and temperature limits are shown independently of each other.


Technologies Pressure Tra Pressure Transmitters nsmitters

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Open Vessel Vessel Level Measur Measur ement In open vessel a pressure transmitter mounted near the bottom of the tank will measure the pressure corresponding to the height of the fluid above it.

Phigh = Phead + Patm Plow = Patm

Patm

Phead Patm

XMTR L

What happen to Atmo At mosp sp her heric ic pr press essur ur e?

H

Cancelled Off Level Level 1 - Level Level



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Transmit Transmit ter mount ed above the tap tap in an open vessel

What happens when the liquid l eve What evell dro p below the sensor ? 100% XMTR 0% L

h

g

H

0%

The sensor will not be able to sense any pressure change !! The 0% has to b e at least least at the same level as the transm itter sensor or below the tapping tapping poin t.. Level Level 1 - Level Level


32

“ Zero Zero Suppression” Suppression” is often applied to compress the range of the transmitter OR to cancel the effects of the liquid head in the pipe connecting the transmitter to a tank when the transmitter is mounted below the vessel connection. At min. level the High side

pressure is high than the low side pressure 20mA

Max. Level

4mA

Min. Level

Ac tu al Zero Suppressed XMTR L

20mA

Max. Level

e g n a R

e g n a R

Ac tu al Zero4mA Suppressed XMTR

H

L

Min. Level

H Level Level 1 - Level Level



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“ Zero Zero Elevation” is often applied to cancel the effects of the head caused by the seal fluid in the reference leg (low side) of a transmitter measuring level in a pressurized vessel.

Max. Level

20mA

4mA Ac tu al Zero Elevated

XMTR

L

e g n a R

Min. Level

At min. level the low side pressure is high than the high side pressure

H



34

Closed Tank Level Measur Measur ement ( Dry Leg ) Dry leg: no fluid in low side impulse piping, or leg

Ulla llage ge or Vapor

If the gas above the fluid does not condense, the piping for the low side of the transmitter will remain empty.

Phigh Plow

= Pto p+Phead = Pto p

Phead XMTR L

H

Phigh - Plow = Phead Level Level 1 - Level Level



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Closed Tank Level Measur Measur ement ( Wet Leg ) Wet leg pressure is additive to pressure on low side of the transmitter. If the gas above the liquid condenses, the piping for the low side of transmitter will slowly fill with liquid. To eliminate this potential error, the pipe is filled with a convenient reference liquid.

Phigh =Phead+Pto p Plo w =Pwe wett le leg g +Pto p

Pto p = Ullage

Pwet

Phead

L H XMTR

Phigh - Plow = Phead head - Pwet wet leg leg Level Level 1 - Level Level


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Limitations • Bottom-mount technology: potential leakage leakage • Often requir es 2 taps taps

Variable densit y creates error s • Variable • Temperatur Temperatur es beyond 600 600 F • High vacuum applications are tricky • Highly corrosiv e processes limit life • Ab ras iv e pr oc ess es c an dam age d iap hr agm s • Liquids Only




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Bubbler System Consists of air supply, pressure regulator, flow meter, transmitter & extended tube.

TXR Pin(flow=const)

Can be used for very corrosive applications. Tank vented.

Pressure to maintain flow = P head Air is bubbled through the tube at a constant flow rate. The pressure required to maintain flow is determined by the vertical height of the liquid above the tube opening times the specific gravity.

H S.Gf

Phead = H * S.Gf Level Level 1 - Level Level


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Gauge Pressure Transmitter

Appl Ap pl icati ic ati on of Bubb Bu bbler ler syst sy stem: em: • Allo Allows ws dp to be a top top down measurement

Valve Air Ai r Supply

• No proc proces ess s cont contac actt with with transmitter • Open Open or low low pre press ssur ure e • Cont Contro roll of of Air Air supp supply ly is important for accuracy




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Remote Seals Reliable, Simple, Easy to Use, Well Understood, Flexible Uses: Diaphragm Seals Diaphragm Seals extend l imit ations due to process conditions such as: high temperatures corrosion viscous materials

Differential Pressure Transmitter

suspended solids plugging sanitary needs



40

Typical Pressure Pressure Applic ations •CPI / HPI Batch reactors

•Pulp & Paper Headbox



digesters fractionators

Stock

distillation

Evaporators

Chemical

column bottoms and reflux drums

concentration liquor tanks... tanks...

surge drums

•Food and Beverage



reservoirs  intermediate storage...

Fermentors storage

•Power

aging

drum

level level  dearators...

Storage tanks

Low

separators 

Tanks



tanks

tanks

brew kettles...

And An d many m any mo re! Level Level 1 - Level Level



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Technologies Radar Gauge

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Frequency Electromagnetic Wavelength, Meters Cycles/second

Spectrum

10 22

gamma rays

10 20

10 -11 x-rays

10 18

ultra violet

10 16

visible light

10 14 10 12 10 10 10 8 10 6

10 -13

10 -9

Radar Radar i s an Electrom Electrom agnetic agnetic Wave Wave Radi Ra di o Detection A etection And nd Ranging

10 -7 10 -5

Radar, 3-30 GHz

10 -3

Microwave oven,

--------super high freq--------------ultra ------ultra high freq-------------------TV broadcasting-----------------FM Radio-------------

10 -1

2 - 10 GHz GHz 10 1 10 3

Cellular, pager,

10 4

10 5

300-3000 MHz

10 2

10 7

-------low frequency------------



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Radar Radar Techniq ues • Pulse » Measures range ( distance ) » Transmits a pulse and measure time until echo is received » Accuracy depends depends on on ability to measure time time – Radar Radar signals tr avel at at the sp eed eed of light. – Must measure in picoseconds ( x10-12 ) ! – Cost-effective Cost-effective electronic electronic s do no t exist to do th is

accurately !




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Radar Radar Techniq ues FMCW:: Frequency Modu Modu lated Continu ous Wave Wave • FMCW » Does NOT calculate time-of-flight time-of-flight » Evaluates the phase difference between the transmitted and return signal » Plotting these phase differences against the transmitted signal yields a result proportional to distance



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Advan Ad vantag tages es of o f Radar Rad ar Gauge Gau ge • Non Contact, Non Non Intrusive

Wide Range Range of Proc ess Condit ions • Tolerates Wide » Corrosive Processes » High Temperatures » Changes in Vapor Space » Variable Density » Variable Dielectric » Viscous or Sticky Products • Low Maintenance • No Special Licenses Required • Can measure long distances • Liquids , pastes, pastes, solids Level Level 1 - Level Level



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Radar Radar Appli cation Considerations • Sensors Sensors can can be complete completely ly remove removed d from from proces process s by use of a window made out of a nonmetallic material, such as Teflon, Ryton, Ceramic • Sensors Sensors can can be removed removed from from the the proce process ss withou withoutt opening the vessel Radar Radar Limit ations • Cost • May not not work with with proces processes ses with with low diele dielectri ctric c constan constantt • May not not work work in applic applicatio ations ns with with large large amoun amounts ts of turbulence • Process Process conne connectio ctions ns tend tend to be large large (>4” (>4” flang flanges) es) Level Level 1 - Level Level


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Possible Applications •Pulp & Paper »High Density Storage

•Chemical »Polymers

»Color tanks »Bleach tanks

»Latex

»Hydropulpers

»LPG tanks

»Retention Retention tanks »Black liquor tanks

»Butane sphere

»High temp

»Batch reactors »Two-phase Two-phase sludg e

•Pharmaceutical »Batch reactor »Chemical Chemical s torage

»Cyclohexane •Minerals

•Power

»Steel Scale Scale Holdin g Tanks

»Slurries

And An d More! Mo re! Level Level 1 - Level Level



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Radar vs. Ultrasonic Gauge

Similarities: Both technologies Top down, non contact Easy to install Good for abrasive materials, slurries Not affected by changing fluid properties: density, conductivity, dielectric

Differences: Radar Full vacuum to several hundred psi Wide temperature limits Can handle steam, fog, vapors Can handle some foams and agitation Can be used with windows

Ultrasonic Very slight vacuum to about 100 psi Narrow temp band (<200 F) Is greatly affected by changes in vapor space Signal is lost in foam and agitation Level Level 1 - Level Level


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Radar vs. Ultrasonic Gauge Gas

Tem p (oC)

RADAR million m/s

ULTRASOUND m/s

Dry Air

0 100

299.91 299.94

331.8 386

Water vapor

100

299.10

404.8

299.85 299.87

250.0 279.0

Carbon Dioxide 0 50 Ammonia

0

299.93

415.0

Acetone

0

297.64

223.0

Source: Instrument Engineer’s Handbook, Liptak Level Level 1 - Level Level



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Technologies Float Mechanis Mechanis m

49

Internal Still pipe to guide the float

External Still pipe to guide the float

Indicator

Float

Float e v l a V

Tank

g n i t a l o s I

Drain Valves

Indicator

Float-operated gauge level-indicator, indicates liquid level in cone or flat roof unpressurise roof unpressurised d tanks. tanks. Recommended for use on tanks storing water, water, fuel, oil, chemicals or other liquid products where operations do not require extreme accuracy. Level Level 1 - Level Level

Other Other technologies Capacitanc e Prob Capacitanc Prob e

50

• A capaci capacitanc tance e instru instrument ment measures measures amount of capacitance between two plates of a capacitor. • The capacitance capacitance of a capacitor capacitor increases if a dielectric dielectric is placed between the plates • Circuit Circuit applies applies high high freque frequency ncy signal signal to probe probe C = KE oAd

k

w h er e K = d i e le le c t r i c c o n s t a n t o f m a t e r i a l Eo = p e r m i t i v i t y o f v a c u u m

A = A r e a o f p la t e s ( p r o b e ) C = c a p a c it it a n c e ( p F ) d = d i st a n c e b et w e e n p la t e s d




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How Capacitance varies with process fluid?

d

Nonconductive Nonconductive Coating

Level is proportional to dielectric change

Level is proportional to plate area change

Nonconduc tive Fluid Fluid

Conductive Fluid

• Proces Process s fluid fluid is is the the dielec dielectr tric ic barrier

• Proces Process s fluid fluid is is the the secon second d plate plate

• Tank Wall forms forms second second plate plate • The vari variati ation on of of dielec dielectri tric c is the the measurement

• Insula Insulation tion on prob probe e is diele dielectr ctric ic • The vari variati ation on of of the the plate plate size size is is the measurement



52

• Limitation

Dielectri c cr eates eates error – Change in Dielectri Coating on p robe by produ ct creates creates errors – Coating metallic tanks or tanks witho ut – With non metallic vertical walls, addition of reference reference probe is required – Calibration Calibration can be diffic ult especially since one cannot “ bench calibrate” calibrate” – Changing Changing vapor space can affect affect ou tput




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Potential Applications

Paper •Pulp & Paper

•Oil & Gas Gas

Sewage level

Water

bottom

Liquor

Water

cut

Bulk

tanks

solids

•Chemical Interface:

fatty acid/water, oil/water Carbon

black

Separators

•Food & Beverage Storage

silos Level Level 1 - Level Level

Other Other technologies Displacers Based Base d on Buoyance Buoyance Force The displacer displacer is buoyed up by a force proportional to the weight of the liquid it displaces

54

0

pounds

0

pounds

Vertical Vertical moveme movement nt of the displacer is converted to angular movement by mechanical linkages

Angular movement movement is then converted to electrical or pneumatic output.

Buoyant force increases as level rise Level Level 1 - Level Level



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Other Other technologies Displacers

55

Good for sh ort sp an measurement measurement

Liquid Level Measurement

Interface Measurement

Density Measurement Level Level 1 - Level Level


56

Benefits: • Simp Simple le,, Reli Reliab able le.. • Good for Interfac Interface e measu measureme rements. nts. • Good for Density Density measurem measurement ents. s. • Unaff Unaffec ected ted by by Agitat Agitation ion.. • Tolerate Tolerates s High Tempera Temperature tures s and pressur pressures. es. • Point Point or Contin Continuo uous us . Limitations: – Does not tolerate viscous, viscous, dirty, dirty, or sticky sticky fluids fluids – Variable density density causes causes errors errors in level measurement measurement – Typically used for smaller spans spans (cost effective) effective) – Must be installed installed carefully carefully – Intrusive & Contact Level Level 1 - Level Level



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• Typical Applications:  Oil

and Water interface  Oil and Gas Separator Separator s  Stripper Reflux Drum Level Dehydration Units  Dehydration  Effluent Separators  Ab so r pt io n To wer s Condensate Discharge Accum ulators  Condensate  Densi Densi ty and Interface Measurements Measurements


Other Other technologies Servo Gauging

58

Uses a combinatio combination n of a displacer displacer and a spring balance The servo motor motor strives strives to obtain an equilibrium between the displacer and the balance. Any change in level will cause a change in equilibrium.

Storage Drum

 Ad van tag es:

– Very precise (1 mm accuracy)

Cable

Balance Detector

Servo Motor

– Can measure level, interface – relatively low cost Limitations:

– Intrusive – Mechanical linkages Displacer




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Other Other technologies Nucleonic Gauging

59

Single Point System Gamma rays are emitted from the source. The presence or absence of the gamma rays is measured by the detector . Gamma Source Nucleonic level switches use radioisotope sources sized to provide measurable radiation at the detector when no product material is present between source and detector.

Detector


Other Other technologies Nucleonic Gauging

60

Continuous System Nucleonic level transmitters use the same radioisotope sources, but respond to the total absorption of gamma rays as they pass from the source to detector.

Source

The amount of radiation reaching the detector is inversely proportional to the amount of material in the vessel. Detector




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Other Other technologies Nucleonic Gauging Advan Ad vantag tages: es: – Unaffected Unaffected by: • High temperatures • High Pressures • Corrosive Materials • Ab ras iv e Material Mater ial s • Viscous Materials • Ag it ati on • Clogging/Plugging

61

Limitations: – Large density density changes changes can create errors – Layer of coating on on vessel walls create errors – Licensing Required – Leak Checks Checks required required – Cost

– Point and Continuous Continuous – Liquids and and Solids – Interface Interface (based on H 2 density) Level Level 1 - Level Level

Other Other technologies Nucleonic Gauging Typical Applications •Chemical

62

•Refining Fractionator or Fractionat

Distillation Tower

Surge

Batch

Coke

Reactor

Storage

Tanks

Resin

Bed level Hydrocracker reactor reactor Hydrocracker •Pulp & Paper Digester Level Wood

Chip Bins

Bleach

Tower

Consistency Effluent

Waste

Slurries Liquor

concentrates

Tower Tower

Tanks

Drum Interface

Desalter

•Food and Beverage Hopper

Level

Blending

Vats Vats

•Mining Crusher

Level

Storage

silos

Slurries

•Utilities SO2

/ Lime scrubber Fly ash Slurries Level Level 1 - Level Level



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Other Other technologies Laser

63

• Function: Uses infrared infrared light light to send a focused beam towards surface. Time of travel travel and reflection reflection is measur measured. ed. • Narrow, focused beam: good for applications with space restrictions. • Non contacting: uses a window • Ac cu rac y: +/+/- 1 cm cm • Works Works best best in clou cloudy, dy, shiny shiny liquids liquids or solids • May pass through through surfaces surfaces of clear, still fluids • Cannot Cannot tolerat tolerate e dust, dust, fog, fog, steam or vapors vapors • High cost • Align Alignme ment nt is is cri criti tica call

glass window

laser device


Other Other technologies Ultrasonic Ultrasonic Gauging Gauging

64

A sou nd p uls e(9 to 160 kHz) kHz) is transmitted and reflects off the surface back to the transceiver. The true reflected echo pulse is extracted and the time interval between transmission and reception is evaluated electronically.

• Advan Ad vantag tages: es:

Sound Waves

Non

Contact No element element c ontamination Can Can be used for liquids and solid s Tolerates Many Many Proc ess Conditions: 9 9 9 9 9

Varying De Varying Density nsity Corrosive Processes Viscous Product Varying Dielectric Sludge Buildup

The higher the level the faster echo reflected Level Level 1 - Level Level



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Appl Ap pl ic ation ati on Consi Con si derati der ati ons on s • Conditions of the vapor space impact speed of signal travel and thus, the measurement • Changes could be due to: – temperature

Sound Waves

– dust – vapor composition – stratification of the vapor

• Some units have temperature compensation • Gas blankets can be used to provide uniform vapor space condition Level Level 1 - Level Level


66

Appl Ap pl ic ation ati on Consi Con si derati der ati ons on s • Proces Process s surfa surface ce con condit ditio ions ns can can affect signal return . Surface must have ability to reflect signal. • Heavy Heavy agita agitatio tion n and and foam foam may may cause signal to be absorbed • Vortex Vortex in in fluid fluid can can misd misdire irect ct sign signal al • In open open,, outdo outdoor or insta installa llatio tions, ns, wind wind can blow signal off coarse • Stilli Stilling ng well wells s can can be use used d to isol isolate ate the surface and contain signal.




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Limitations – not suitable for vacuum service – Canno Canno t to lerate high temperatures (>20 (>200 0 F) – Foam Foam in terferes terferes with signal

na l – Ag it ati on may di st or t s ig nal – Internal obst acles can create false false echoes – Nearby equipment could generate frequencies that will cause errors

Vapor pressure limited to 50 psi – Vapor


Other Other technologies Ultrasonic Ultrasonic Gauging Gauging Typical Applications •Chemical Distillation

68

•Waste water Clarifier

chamber

Corrosives Slurries Latex

Settling Settling

tanks Reservoirs Flood control Sludge levels

PVC Waxes

•Pulp & Paper

•Food and Beverage

Black

Dearating ting Deara

vessel vessel fermenter alcohol fermenter baking batter chocolate dairy products grain storage •Cryogenic systems (point level)

liquor w/ solids

•Pharmaceutical Emulsions Lotions

•Marine Fuel or ballast water indication Bilge alarm Level Level 1 - Level Level



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Exercise

69

1. Which has the the best accuracy accuracy on 6 meter meter High Water Water tank? A. Hollow or glass fill float with mechanical gauge (1 inch) B. “Ser Servo” vo” Gaug Gauge e (1 (1 mm) mm) C. Pressure Transmitter ±0.1% of F.S [ ] 2. An inground inground reservoir reservoir is 5 meters meters deep. Which of of the followin following g method(s) will be suitable to measure and transmit the level without having to dig a hole to reach reach the bottom of the reservoir or the scour main. (Answer Yes [Y] or No [N]) A. B. C. D. E. F. G.

Differential Pressure Servo Level Gauge Capacitive Probe Nucleonic Gauging Ultrasonic Gauging Radar Gauging Bubbler System

[ [ [ [ [ [ [

] ] ] ] ] ] ] Level Level 1 - Level Level

Exercise

70

3. For HTG, HTG, why is a 2nd Pressure Pressure Transmitt Transmitter er added to tank tank in the middle ?

4. Which one of the the following following tank gauging gauging system system is based on Mass? Mass? (A) Radar (B) Nucleonic nic (C) (C) Serv Servo o Bala Balanc nce e (D) HTG [ ]

5. Which of the the following following statement statement about about Radar Gauge Gauge is NOT True True ? (A) (A) TopTop-do down wn moun mounti ting ng (B) Can hand handle le agitat agitated ed & stick sticky y proces process s fluid fluid (C) Can be used on on a tank tank with with non-metal non-metallic lic internal internal surface. surface. (D) Can handle process with deep vacuum [ ]




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Exercise

71

6.

5’

Assuming SG is is = 1.1 What is the volume?____________ft3 What is the density of this this fluid?___________#/ft3

10’

What is the mass?__________pounds What is the pressure level reading? ________in H2O

water = 62.4 # / ft 3


Exercise

72

7. Now, suppose the SG changes to 1.05 and the

5’

level does not change What is the volume?____________ft3 What is the density of this fluid?___________#/ft3

10’

What is the mass?__________pounds What is the pressure level reading? reading? _______in

H2O

water = 62.4 # / ft 3




Exercise

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8. Pmeasured = 150 inH2O s.g.

Pin(flow=const)

= 1.5

What is the fluid level in the tank?



Training - Level

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