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INSTRUMENTATION
(Presented by G D Rathi)
WHAT IS INSTRUMENTATION?
WHAT IT CONSISTS?
INSTRUMENTATION
IT IS WINDOW TO PROCESS OF PLANT.
PROCESS IS SEEN BY FOLLOWING
PARAMETERS.
o Flow
o Level
o Temperature
o Pressure
o Density
INSTRUMENTATION
o Viscosity
o Speed
Analyzer (Analyzing following parameters)
• pH
• Conductivity
• O2
• Sulphur
• H2S and so on.
o Vibrations of Compressor, Pumps
(Equipments)
INSTRUMENTATION
MEASUREMENT OF ALL ABOVE PROCESS PARAMETERS & CONTROLLING OF THESE PARAMETERS IS INSTRUMENTATION.
INTERFACE OF INSTRUMENTATION IS WITH PROCESS, ELECTRICAL, PIPING, MECHANICAL EQUIPMENTS.
AUTOMATION IS PART OF INSTRUMENTATION.
INSTRUMENTION PERSON SHOULD KNOW THE PROCESS.
FIRE & GAS DETECTION SYSTEM
WHAT IT CONSISTS OF?
FOLLOWING ARE MAJOR COMPONENTS OF
INSTRUMENTATION CLOSED LOOP.
TRANSDUCER, SENSOR
TRANSMITTER
CONTROLLER
FINAL CONTROL ELEMENT
WHAT IT CONSISTS OF?
FUNCTION /LOCATION OF THESE COMPONENTS IN PROCESS PLANTS.
TRANSDUCER, SENSOR Which senses the process parameters, located on pipe or
vessel or at process equipment.
Can be combined with transmitter.
Process parameter sensed by sensor is converted in to electrical signal like millivolt or resistance or current.
TRANSMITTERWhich converts the signal from sensor to standard
electrical or pneumatic signal.
Standard electrical signal = 4 to 20 ma.
Standard pneumatic signal = 3 to 15 psig. (0.2 to 1 Kg/cm2g)
WHAT IT CONSISTS OF?
FUNCTION /LOCATION OF THESE COMPONENTS IN PROCESS PLANTS.
CONTROLLER : It is arithmetical block controls through PID function which
is proportional, integral, derivative action. (PID Tuning)
It can be single loop controller or multi loop controller.
Now days these controllers resides at DCS / PLC microprocessor based computer system.
DCS – Distributed Control system
PLC – Programmable Logic Controller
FINAL CONTROL ELEMENT :Controller output goes to Final control Element.
It can be Control Valve, VFD, Damper, MOV, On/Off Valve.
INSTRUMENTATTION
LOCAL INSTRUMENTS
o PRESSURE GAUGES
o TEMPERATURE GAUGES
o LEVEL GAUGES
o DP INDICATORS
o GLASS TUBE ROTAMETERS
INSTRUMENTATTION
General software used
o INtools for inst index, hook ups,
sizing of all types instruments
o InstCal for sizing control valves,
orifice plates, safety valves and so
on.
o PDS / PDMS for modeling.
Marshalling Rack Room
System Architecture:
DCS Operator Station
Snap Shot of Control Room
INSTRUMENTATTION
HAVE LOOK AT CONTROL LOOP
INSTRUMENTATTION
FEEDBACK CONTROL LOOP
INSTRUMENTATTION
FEEDFORWARD CONTROL LOOP
TYPES OF FLOW MEASUREMENTS
AND
THEIR APPLICATIONS
(Presented by G D Rathi)
TYPES OF FLOWMETERS
PRINCIPLE OF OPERATION
FEATURES OF FLOWMETERS
ADVANTAGES AND DISADVANTAGES
SELECTION/ APPLICATION OF A FLOWMETER
TYPES OF FLOWMETERS
VOLUMETRIC FLOWMETERS
Differential Head type
o Orifice plates
o Venturi meters
o Annubar
Differential Area type (Rotameters)
Electromagnetic flowmeters
Ultrasonic flowmeters
Turbine flowmeters
Vortex flowmeters
Positive Displacement Meters
MASS FLOWMETERS
Coriolis Mass flowmeter
Thermal Mass flowmeters
DIFFERENTIAL HEAD TYPE FLOWMETERS (ORIFICE)
Difference in pressure exists betweenthe upstream & downstream sides of arestriction in a confined fluid stream,which related to the square of fluidvelocity.
– Q α √ ▲P
where
– Q = Volume flow rate
– ▲P = Differential pressure between taps
DIFFERENTIAL HEAD TYPE FLOWMETERS (ORIFICE)
Types of Orifice plates
Concentric orifice plate:
Most commonly used
Segmental & Eccentric orifice plate
Used for fluids containing
suspended solids.
Tappings for the Orifice plates
Integral orifice plate (< = 1”)
Calibrated Meter run with
Corner Taps for 1.5”
Flange taps ( 2” to 12”)
D and D/2 taps ( <= 14”)
FEATURES OF ORIFICE PLATES
Design Pressure: No limitation. Limited by DP transmitter
Design Temperature: No limitation. Limited by DP transmitter
Sizes: Maximum size is pipe size
Flow range: limited only by pipe size.
Fluids/ Applications: Cryogenic(- Low Temp) / clean gases & liquids/
Steam (saturated/superheated)
MOC: No limitation (Steel/ monel/nickel/ haste alloy)
Accuracy : Totality It is from ±0.1% to ±1% of actual flow.
Rangeability is 3:1 to 5:1.
Upstream length/ Downstream straight length is 20D / 5D (D is pipe diameter)
ADVANTAGES OF ORIFICE PLATES
Easily installed between flanges.
Fabrication simple and inexpensive.
No limitations on the materials of construction, line size and flow rate
Cost relatively independent of pipe diameter since cost of DPT is fixed.
No process interruption for exchange of DP transmitter.
DISADVANTAGES OF ORIFICE PLATES
`
High permanent pressure loss & hence high energy consumption toovercome pressure loss.
Impractical for systems with low static pressure.
Measuring range to about 3:1 to 5:1. ``
VENTURI METERS
A venturi tube also measures flow rates by constricting fluids
and measuring a differential pressure drop.
In the upstream cone of the Venturi meter, velocity is increased,
pressure is decreased.
Pressure drop in the upstream cone is utilized to measure the
rate of flow through the instrument
FEATURES OF VENTURI METERS
Design Pressure: No limitation. Limited by DP transmitter/ pipe press.ratings.
Design Temperature: No limitation. Limited by DP transmitter/ pipe pressure ratings
Sizes: 25 mm to 3000 mm
Fluids/ Applications: Clean Liquids/ clean gases
: Limited applications: Dirty /corrosive/viscous Liquids & Dirty gases
MOC: No limitation (cast iron/ carbon steel/ SS/Monel, Titanium, Teflon, Hastelloy, Naval Bronze / haste alloy)
Rangeability is 3:1 to 5:1.
Upstream length/ Downstream straight length is 20D / 5D ( D is pipe diameter)
ADVANTAGES OF VENTURI METERS
Lower head losses than orifice plates reducing the capitalexpenditure on pumping eqpt. / save pump energy costs
No process interruption for exchange of DP transmitter.
Can be used for temperature extremes
– Cryogenics or High Temperatures
DISADVANTAGES OF VENTURI METERS
Highly expensive
Larger and heavier to handle.
ANNUBAR FLOWMETER
The probe is installed in the media line as apressure sensor.
With the flow, the probe records both the staticand the dynamic pressure via the probeopenings .
In the minus chamber of the annubar, lying onthe opposite side, only the static pressure hasany effect
The differential pressure corresponds to thedynamic pressure in the pipeline & the flow canis calculated directly.
ANNUBAR FLOWMETER
ANNUBAR FLOWMETER
FEATURES OF ANNUBAR
Sizes: 50 mm to 3000 mm
Fluids : Clean Liquids, gases and steam
MOC: Brass / steel/ stainless steel/ Hastelloy
Rangeability is 3:1 to 5:1.
Upstream length/ Downstream straight length is 20D / 5D
ADVANTAGES OF ANNUBAR
Integral manifold head allows direct mounting of DPtransmitters
Hot tapping: Insertion/ installation without system shutdown
Very low pressure drop
DISADVANTAGES OF ANNUBAR
Not suitable for viscous and slurry applications
Can be used for only for clean fluids
VARIABLE AREA FLOWMETER
o A free moving
float is balanced
inside a vertical
tapered tube
o As the fluid flows
upward the float
remains steady
when the dynamic
forces acting on it
are zero.
o The flow rate
indicated by the
position of the
float relative to a
calibrated scale.`
VARIABLE AREA FLOWMETER
FEATURES OF ROTAMETERS
Sizes: upto 75 mm
Fluids/ Applications : Clean liquids, gases and vapours
Flow range: upto 920 cub.m/hr for liquids & 2210 cub.m/hr for gases
MOC: Borosilicate glass/ brass / steel/ stainless steel/ Hastelloy
Accuracy : It varies from ±1% to ±2% of actual flow.
Rangeability is 10:1
Upstream length/ Downstream straight length is 10D / 5D
ADVANTAGES OF ROTAMETERS
Simple, robust and linear output
Does not require external impulse or lead lines.
Pressure drop is minimal and fairly constant.
DISADVANTAGES OF ROTAMETERS
Vertical installation only.
Glass tubes limit pressure & temperature and subject to breakage from hydraulic & thermal shock
Metal tube meters more expensive.
Foreign particles can accumulate around the float & block the flow
MAGNETIC FLOWMETERS
Operate on Faraday’s Law
of magnetic induction.
When a conductive fluid
moves in a magnetic field,
a voltage is generated
between two electrodes at
right angles to the fluid
velocity and field
orientation.
The flow tube has a fixed
area & field intensity so
the developed voltage is
linearly proportional to the
volumetric flow rate.
MAGNETIC FLOWMETERS
FEATURES OF MAGNETIC FLOWMETERS
Design Pressure: 20 BARS to 172 BARS
Design Temperature: Upto 120 deg.C with teflon liners /
180 Deg.C with ceramic liners
Sizes: 2.5 mm to 3000 mm
Fluids : Liquids (clean/ corrosive/dirty/viscous/ slurry)
Velocity range: 0.1 to 10 m/s
MOC: Liners: ceramic/ teflon/rubber
: Electrodes: Platinum/ hastelloy/SS
Accuracy : It varies from ±0.5% to ±1% of actual flow.
Rangeability is 10:1
Upstream length/ Downstream straight length is 10 / 5
ADVANTAGES OF MAGNETIC FLOWMETER
Flow rate unaffected by fluid density, consistency, viscosity, turbulence, or pipingconfiguration.
Highly accurate due to absence of moving parts/ external sensing lines
Corrosion-resistant using Teflon liner and platinum electrodes
Wide flow measuring ranges & no pressure drop.
No Moving Parts. No Wear & Tear on components.
DISADVANTAGES OF MAGNETIC FLOWMETER
Costly, relative to other flowmeter types.
Temperature of the fluids being metered limited by the liner material rating.
Cannot be used for gas flow measurements
VORTEX FLOWMETERS
Vortex meters make use of a natural phenomenon
that occurs when a liquid flows around a bluff object.
Eddies or vortices are shed alternately downstream of
the object. The frequency of the vortex shedding is
directly proportional to the velocity of the liquid flowing
through the meter
VORTEX FLOWMETERS
An obstruction is placed across the
pipe bore at right angle to fluid flow.
As fluid flows, vortices are shed
from alternating sides of the body &
this shedding frequency is directly
proportional to fluid velocity.
Detection of the vortices by means
of pressure changes in the vortex
stream.
Rate of creation of vortices directly
proportional to the flow rate.
VORTEX FLOWMETERS
VORTEX FLOWMETERS
FEATURES OF VORTEX FLOWMETERS
Design Pressure: 138 bars
Design Temperature: -200 Deg. C to 400 Deg.C
Sizes: 15 mm to 300 mm
Fluids : Gases (clean/ dirty) and clean liquids
Velocity range: 0.3 to 10 m/s (liquids) and 6 to 80 m/s (gases)
MOC: mostly in stainless steel, some in plastic
Accuracy : It varies from ±0.5% to ±1% of actual flow for liquids and
±1% to ±1.5% for gases
Rangeability is 20: 1
Upstream length/ Downstream straight length is 20 / 5
ADVANTAGES OF VORTEX FLOWMETERS:
Minimal maintenance, no moving parts.
Calibration using fluid flow not required & unaffected by viscosity, density, pressure, and temperature within operating specification.
Digital or analog output.
DISADVANTAGES OF VORTEX FLOWMETERS
At low flows, pulses are not generated and the flowmeter can read low or even zero.
Reynolds number should be greater than 10000
Vibration can cause errors in accuracy.
Correct installation is critical as a protruding gasket or weld beads can cause vortices to form, leading to inaccuracy.
Long, clear lengths of upstream pipework must be provided, as for orifice plate flowmeters.
ULTRASONIC FLOWMETERS
A pair (or pairs) of transducers, each having its own transmitter and
receiver, are placed on the pipe wall, one (set) on the upstream and
the other (set) on the downstream.
The time for acoustic waves to travel from the upstream transducer
to the downstream transducer td is shorter than the time it requires for
the same waves to travel from the downstream to the upstream tu.
The larger the difference, the higher the flow velocity.
FEATURES OF ULTRASONIC FLOWMETERS
Design Pressure: 207 bars (insertion type)/ unlimited (clamp on type)
Design Temperature: -180 Deg. C to 260 Deg.C
Sizes: 3 mm to 3000 mm
Fluids : clean gases, clean/corrosive liquids (with little/no solids/ bubbles)
Velocity range: 0.3 to 15 m/s
MOC: mostly in stainless steel/ alloyic
Accuracy is
+0.5% of flowrate for insertion type
+1% to +3% of flowrate for clamp on type
Range ability is 10 : 1 to 300 : 1
Upstream length/ Downstream straight length is 10 / 5
Bidirectional flow measurement
For insertion type, hot tapping in pressurised pipelines possible
ADVANTAGES OF ULTRASONIC FLOWMETERS
¤ No obstruction/ moving parts in the flow path
¤ No pressure drop
¤ Low maintenance cost
¤ Multi-path models have higher accuracy for wider ranges of Reynolds number
¤ Can be used in corrosive fluid flow
¤ Portable models available for field analysis and diagnosis
DISADVANTAGES OF ULTRASONIC FLOWMETERS
Only clean liquids and gases can be measured
Higher initial set up cost
Limited Acceptance in water & chemical industries.
TURBINE FLOWMETERS
Consists of a multi-bladed rotor
mounted at right angles to the flow &
suspended in the fluid stream on a
free-running bearing.
The diameter of the rotor is slightly
less than the inside diameter of the flow
metering chamber.
Speed of rotation of rotor
proportional to the volumetric flow
rate.
FEATURES OF TURBINE FLOWMETERS
Design Pressure: 1500 PSIG
Design Temperature: 150 Deg. C
Sizes: 5 mm to 600 mm (Full bore type)/ > 75 mm for insertion type
Fluids : Clean liquids/ gases and vapours
Velocity range: 0.3 to 15 m/s
MOC: mostly in stainless steel/ hastelloy
Accuracy is
+0.25% to + 0.5% of flowrate for full bore type
+1% to +3% of flowrate for insertion type
Range ability is 10 : 1
Upstream length/ Downstream straight length is 15/ 5
Bidirectional flow measurement
For insertion type, hot tapping in pressurized pipelines possible
ADVANTAGES OF TURBINE FLOWMETERS
Very accurate. Commonly used to prove other meters.
Digital output provides for direct totalizing, batching, or digital blending without reducing accuracy.
There is less tendency to read high in pulsating flow than in head or variable-area type meters.
DISADVANTAGES OF TURBINE FLOWMETERS
Not usable in dirty streams or with corrosive materials.
Subject to fouling by foreign materials -fibers, tars etc.
Bearings subject to wear or damage. Shift in calibration if bearings replaced
Can be damaged by overspeeding (over 150 percent) or by hydraulic shock.
Pressure loss at rated flow varies & can be high.
TURBINE FLOWMETERS
This meter repeatedly entraps the
fluid into a known quantity and than
passes it out.
The quantity of the fluid that has
passed is based on the number of
entrapments.
The volume flow rate can be
calculated from the revolution rate of
the mechanical device.
POSITIVE DISPLACEMENT METERS
FEATURES OF PD FLOWMETERS
Design Pressure: 1500 PSIG (liquids)
: 100 psig (gases)
Design Temperature : 293 Deg. C (liquids)
: -34 to 60 Deg. C (gases)
Sizes: 6 mm to 400 mm
Fluids : Clean Liquids/ gases
Flow range: 0 - 20000 GPM (liquids)
: 0 - 3000 cub.m/hr (gases)
MOC: mostly in aluminum,stainless steel, plastics, hastelloy
Accuracy is + 0.5% to + 1% of flowrate
Range ability is 15 : 1
ADVANTAGES OF PD FLOWMETERS
¤ Good accuracy and high range ability
¤ Can be used in viscous liquid flow
¤ Low to medium initial set up cost
¤ Require no power supply and available in wide variety of read out devices
DISADVANTAGES OF PD FLOWMETERS
¤ Maintenance required at frequent intervals because of the `moving parts.
¤ High pressure drop due to obstruction
¤ Not suitable for low flow rate
¤ Not suitable for fluids with suspended solids
¤ Gas (bubbles) in liquid could significantly decrease the accuracy
Operates by monitoring the cooling effect of a gas
stream as it passes over a heated transducer.
Gas flows passes over two PT100 RTD
transducers.
The temperature transducer monitors the actual
gas process temperature, whilst the self-heated
transducer is maintained at a constant differential
temperature by varying the current through it.
The greater the mass flow passing over the
heated transducer, the greater current required to
keep a constant differential temperature.
The measured heater current is therefore a
measure of the gas mass flowrate.
THERMAL MASS FLOWMETER
FEATURES OF THERMAL MASS FLOWMETERS
Design Pressure: 1200 PSIG
Design Temperature: 176 Deg. C
Sizes: 15 mm to 1000 mm
Fluids : Clean gases
Flow range: 0 – 2500 SCFM
MOC: mostly in stainless steel/ glass, teflon, monel
Accuracy is +1% to + 2% of flowrate
Range ability is 10 : 1 to 100:1
Upstream length/ Downstream straight length is 5/ 3
ADVANTAGES OF THERMAL MASS FLOWMETER
No temperature or pressure compensation required
Linear output (as temperature differential is proportional to mass flow)
Can be used on corrosive process streams if proper materials are specified
DC voltage or 4 to 20 mA dc outputs available
DISADVANTAGES OF THERMAL MASS FLOWMETER
Practical for gas flows only
Subject to blockage by foreign particles or precipitated deposits due tosmall openings in flowmeter
Power requirements excessive in larger pipe sizes
Has to taken out of process line for servicing
Accurate field calibration is difficult
When a moving mass is subjected to anoscillation perpendicular to its direction ofmovement, Coriolis forces occur depending onthe mass flow.
When the tube is moving upward during the
first half of a cycle, the fluid flowing into the
meter resists being forced up by pushing down
on the tube.
On the opposite side, the liquid flowing out
of the meter resists having its vertical motion
decreased by pushing up on the tube. This
action causes the tube to twist.
This twisting movement is sensed by a pick
up and is directly related to mass flow rate
CORIOLIS MASS FLOWMETER
When fluid is moving through the sensor's tubes, Coriolis
forces are induced in both the inlet and outlet legs of both
flow tubes. These forces cause the flow tubes to twist in
opposition to each other.
The mass flow moving through the inlet legs of the flow
tubes generate a Coriolis force that resists the vibration of
the flow tubes. As the mass flow moves through the outlet
legs, the Coriolis force adds to the vibration of the flow
tubes.
It is the opposite direction of the Coriolis force between
the inlet and outlet legs that result in the twisting motion that
is used to measure mass flow rate.
CORIOLIS MASS FLOWMETER
CORIOLIS MASS FLOWMETER
Coriolis Mass Flow meters also measures density. Natural Frequency is basis ofmeasurement of density in coriolis mass flow meter.
Drive coil causes the tube to oscillate at natural frequency. As the mass in
process fluid increases, natural frequency decreases. As the mass of process fluid
decreases, natural frequency of tube increases.
Frequency is measured in cycles per second and Tube period is the reciprocal
of natural frequency. Coriolis Mass Flow meter measures density by measuring
tube period in microsecond per cycles.
Fluid Density is directly related to measure tube period.
CORIOLIS MASS FLOWMETER (DENSITY)
Coriolis Mass Flow meter
FEATURES OF CORIOLIS MASS FLOWMETERS
Design Pressure: 345 bar
Design Temperature: 200 to 426 Deg. C
Sizes: 1.5 mm to 150 mm
Fluids/ Applications : Liquids (clean/ dirty/viscous/ slurries) clean /liquified gases
Flow range: 0 – 25000 lb/m
MOC: mostly in stainless steel, hastelloy/titanium
Accuracy is + 0.15% to + 0.5% of flowrate
Range ability is 20 : 1
Bidirectional flow measurement
ADVANTAGES OF CORIOLIS MASS FLOWMETERS
¤ Capable of measuring difficult handling fluids
¤ Independent of density changes, flow profile and flow turbulence.Hence straight lengths are not required.
¤ No routine maintenance required since no moving parts
¤ High accuracy
DISADVANTAGES OF CORIOLIS MASS FLOWMETERS
¤ Not available for large pipes (upto 150 mm only)
¤ High flow velocities required for detection resulting in high pressure drop
¤ Expensive compared to other flowmeters
¤ Difficulty in measuring low pressure gases.
APPLICATIONS OF FLOWMETERS
• CLEAN LIQUIDS/ GASES
• Orifices
• Venturi
• Annubar
• Variable Area
• Magnetic (only liquids)
• Ultrasonic
• Vortex
• Coriolis Mass Flowmeters
• Thermal mass flowmeter (only gases)
• PD meters
APPLICATIONS OF FLOWMETERS
• DIRTY LIQUIDS
Most suited
• Magnetic
• Coriolis Mass Flowmeters
Limited applications
• Venturi meters
• DIRTY GASES
Most suited
• Vortex meters
Limited applications
• Venturi meters
• Thermal mass flowmeter
• Variable area flowmeter
APPLICATIONS OF FLOWMETERS
CORROSIVE LIQUIDS
• Magneticflowmeters
• Ultrasonic flowmeters
VISCUOUS LIQUIDS
• Coriolis
• Magnetic
• Positive Displacement Meters
APPLICATIONS OF FLOWMETERS
ABRASIVE SLURRIES
• Magnetic flowmeters
• Coriolis Mass Flowmeters
FIBROUS SLURRIES
• Magnetic flowmeters
• Coriolis Mass Flowmeters (limited applications)
SATURATED STEAM
Most suited
• Orifice DP meters
• Vortex flowmeters
Limited applications
• Venturi meters
• Variable area meters
SUPERHEATED STEAM
Most suited
• Orifice DP meters
Limited applications
• Venturi meters
CRYOGENIC ( Low Temperatures)
• Venturi meters
• Orifice plates
APPLICATIONS OF FLOWMETERS
LEVEL INSTRUMENTATION
(Presented by G D Rathi)
TYPES OF LEVEL INSTRUMENTS
• LEVEL GAUGEMAGNETIC LEVEL GAUGE
RELEX GLASS TYPE LEVEL GAUGE
FLOAT & TAPE TYPE LEVEL INDICATOR
• LEVEL TRANSMITTERDISPLACER TYPE
RADR LEVEL TRANSMITTER
SERVO GAUGE TYPE LT
DP TYPE LT
NUCLEONIC TYPE LT
ULTRASONIC TYPE LT
LEVEL INSTRUMENTATION
LEVEL INSTRUMENTATION
• LEVEL SWITCHES VIBRATION FORK TYPE LEVEL SWITCHES
CAPACITANCE TYPE LEVEL SWITCHES
FLOAT TYPE LEVEL SWITCHES
REED TYPE LEVEL SWITCHES
LOOK AT HOOK UP OF LEVEL INSTRUMENTS
LEVEL INSTRUMENTATION
RADAR LEVEL
INSTRUMENTS:-
- Used for Continuous Non-
contact Level
measurement of Liquids,
Paste and Slurries.
-For High Pressure and
Temperature.
- Accuracy +/- 1 to 10 mm
- Dielectric Constants shall
be > 1.4
LEVEL INSTRUMENTATION
Radar Level Transmitter (Antena Type)
LEVEL INSTRUMENTATION
RADAR LEVEL INSTRUMENTS:-
Radar Level measurement using the Time-of-Flight principle.
Radar works with high-frequency radar pulses which are emitted by an antenna and reflected from the product surface. The time of flight of the reflected radar pulse is directly proportionate to the distance traveled. If the tank geometry is known, the level can be calculated from this variable.
LEVEL INSTRUMENTATION
GUIDED WAVE RADAR LEVEL INSTRUMENTS:-
Guided Wave radar works with high-frequency radar pulses which are guided
along a probe. As the pluses impact the medium surface, the characteristic
impedance changes and part of the emitted pulse is reflected.
The time between pulse launching and receiving is measured and analyzed by
the instrument and constitutes a direct measure for the distance between the
process connection and the product surface.
Reliable and maintenance-free measurement in liquids, also in turbulent media
and foam. Unaffected by density, temperature, conductibility and humidity.
No impairment by outgassing media (steam pressure).
Process temperatures up to +400 °C
Process pressures up to 400 bar
LEVEL INSTRUMENTATION
GUIDED WAVE RADAR
LEVEL INSTRUMENTS:-
Up to 45 meter tank.
Used for Interface Level,
continuous Liquid Level
and solid level
measurement.
Accuracy +/- 2 mm to 10
mm.
LEVEL INSTRUMENTATION
DP TYPE LEVEL
INSTRUMENTS:-
Used for Liquid Level
Measurement.
Accuracy +/- 0.5 to +/-
0.075% of FS
LEVEL INSTRUMENTATION
DP TYPE LEVEL INSTRUMENTS:-
The pressure difference which acts on both sides of the sensor leads to a deflection of the diaphragm. This deflection is converted into a pressure-proportionate output signal.
Unaffected by dielectric constant, foam, turbulence and baffles. High overload resistance.
– Process temperatures up to +350 °C
– Process pressures up to 40 bar
LEVEL INSTRUMENTATION
Servo Gauge Level Instruments:-
Servo Tank Gauging measurement is based on the liquid displacement principle. A displacer is suspended in a liquid by a wire. The weight of the displacer is measured, compared to a target value, and the result of this comparison is output as level or density data.
For continuous contact level measurement of liquids and liquefied gases, including liquid surface level, the interface between 2 liquids, and tank bottom. It is also applicable for density measurement.
LEVEL INSTRUMENTATION
Servo Gauge Level Instruments:-
Accuracy +/- 0.7 mm
Measures two clear interface levels and specific
gravity of up to three liquid phases
Tank mounted intelligence makes ideal for single or
multi-task installation, converting a wide range of
measurement functions including:
Liquid level Interface level, Spot density, Density
profile, Tank bottom, Water dip
Typical areas of apllication includes - Oil (fules),
LPG/LNG, Chemicals, Water /chemical interface
measurement, Foods, Liquid Food
LEVEL INSTRUMENTATION
Capacitance Type Level Instruments:-
A capacitance probe may be compared to an electric condenser. As the tank is filled, the probe capacity increases. This change is electrically analyzed.
Available with active build-up compensation for highly viscous media.
High temperature probe or applications involving extremely high temperatures.
Process temperatures up to +400 ° c, Process pressures up to 500 bar
LEVEL INSTRUMENTATION
Capacitance Type Level Instruments:-
Used for continuous measurement of liquid .
Used for point detection level in solids, liquids.
LEVEL INSTRUMENTATION
Capacitance Type Level Instruments:-
LEVEL INSTRUMENTATION
NUECLONIC LEVEL INSTRUMENTS:-The gamma source, a cesium or cobalt isotope, emits radiation
which is attenuated as it passes through materials. The measuring
effect results from the absorption of radiation by the product to be
measured which is caused by level changes
Non-invasive measurement from outside for all extreme
applications, e.g. very corrosive, aggressive and abrasive media.
Any process temperature
Any process pressure
LEVEL INSTRUMENTATION
NUECLONIC OR RADIOMETRIC LEVEL
INSTRUMENTS:-
LEVEL INSTRUMENTATION
NUECLONIC OR RADIOMETRIC LEVEL LIMIT DETECTION:-
LEVEL INSTRUMENTATION
NUECLONIC OR RADIOMETRIC LEVEL LIMIT
DETECTION:-
The gamma source, a cesium or cobalt isotope, emits radiation which is
attenuated as it passes through matter.
The measuring effect results from the absorption of the radiation by the
product.
Non-contact from outside.
For all extreme applications like toxic or highly aggressive media or rocks.
Any process temperature
any process pressure
LEVEL INSTRUMENTATION
Vibrating Level Switch
A sensor in form of a tuning fork is excited at its resonant frequency. The
drive works piezoelectrically. The oscillating frequency or the amplitude
changes as the fork enters the medium.
The change is analyzed and translated into a switching signal.
Free of calibration and maintenance. For all liquids, also if build-up,
turbulence or air bubbles occur, unaffected by the electric properties of
the medium.
Process temperatures up to +280 °C
Process pressures up to 100 bar
LEVEL INSTRUMENTATION
Vibrating Level Switch
LEVEL INSTRUMENTATION
Magnetic Level Gauge
LEVEL INSTRUMENTATION
Float Type Level Switch:-
As the switch floats up and down on the surface of a liquid, an
installed sensor detects its position and triggers the switching operation.
Simple and price-effective. For liquids like water, waste water, acids.
Process temperatures up to +80 °C
Process pressures up to 3 bar
LEVEL INSTRUMENTATION
Float Type Level Switch:-
LEVEL INSTRUMENTATION
Reflex Type Level Gauges:-
INSTRUMENTATION
(Presented by G D Rathi)
Pressure Instruments
Temperature Instruments
Level Instruments
PRESSURE INSTRUMENTATION
Diaphragm Type Pressure Gauges :- Used
• Bourdon Tube type Gauges
• Diaphragm Type Gauges
• Diaphragm Seal Type Gauges
• Bellows
Material:- .
• All wetted parts shall be minimum SS 316.
• Movement – SS304 minimum
PRESSURE INSTRUMENTATION
Bourdon Tube PG:
• Used normally up to 60 DegC.
• Range Min. -1 to 1600 Kg/cm2g.
• Argon Arc Welded 316 SS Bourdon Tube.
• Dial Size – 40, 50, 63, 100, 150, 250 mm.
• Normally used 150 mm.
• Connection – 3/8”, ½”, ¾” up to 1.5” NPT,
BSP threads.
• Connection – Bottom, Back as specified.
Bourdon Tube Pressure Gauge
PRESSURE INSTRUMENTATION
Bourdon Tube PG:
• Mounting – Field or Panel.
• Connection – ½” NPT (M) normally used.
PRESSURE INSTRUMENTATION
Bourdon Tube PG:
• Over range protection :– 130% of FSD.
• Accuracy: - +/- 1 % of FSD
• Zero point adjustment.
• Blow out disc for safety.
• Glycerin filled used for vibration, shocks.
PRESSURE INSTRUMENTATION
Diaphragm seal type PG:-
• Used where fluid is corrosive, viscous,
sediments, tendency to freeze, hazardous
fluid.
• To isolate Bourdon tube from process fluid.
• Seal Fluid – inert Liquid, Silicon – DC200,
DC750 based on Temperature.
• Direct mounted or else capillary to be used for
remote mounting.
PRESSURE INSTRUMENTATION
Diaphragm seal type PG:-
• Connection – Bottom, ½” to 3” flanged, 150#
to 2500#, RF, RTJ, FF available.
• Diaphragm Material – SS316, Hastelloy C,
SS316+PTFE, Inconel, Nickel based on
application.
• Std. Capillary length – 3 mtr.
• Diaphragm sensing are also used without seal
for low pressure sensing, where 0 – 10000
mmWC.
PRESSURE INSTRUMENTATION
Diaphragm seal PG Construction-
PRESSURE INSTRUMENTATION
Diaphragm seal PG-
PRESSURE INSTRUMENTATION
Diaphragm seal PG-
PRESSURE INSTRUMENTATION
Diaphragm seal remote PG (with Capillary):-
PRESSURE INSTRUMENTATION
Pressure Switches:-
• Pressure switches are used detect high or low,
normally it is blind pressure switches.
• Differential pressure switches are used to detect lo or
hi Differential pressure.
• Indicating switches are also available.
PRESSURE INSTRUMENTATION
Pressure & DP Transmitters:-
PRESSURE INSTRUMENTATION
Diaphragm Seal type Direct Mounted Pressure
Transmitters:-
PRESSURE INSTRUMENTATION
Diaphragm Seal type Remote Pressure
Transmitters:-
PRESSURE INSTRUMENTATION
Diaphragm Seal type Remote & Inline Pressure
Gauges / :-
PRESSURE INSTRUMENTATION
Differential Pressure Gauge
PRESSURE INSTRUMENTATION
Accessories:-
• Syphon :- Used in steam service to reduce temp.
• Snubber:- Used at Pump Discharge to reduce fluctuation, provides dampening effect.
• Gauge Saver:- Used where maximum pressure exceeds the over range pressure of gauge.
• 2-Valve manifold for PG
• 3-Valve Manifold for Differential Pressure Indicators.
PRESSURE INSTRUMENTATION
3-way valve Manifold
PRESSURE INSTRUMENTATION
5-way Manifold
PRESSURE INSTRUMENTATION
Accessories:-
PRESSURE INSTRUMENTATION
Accessoris:- 2 Valve Manifold
TEMPERATURE INSTRUMENTATION
Bimetal Dial Thermometers
• Bottom , Back entry
• Every angle type
• Range -50 to 600 DegC
• Protection – 125% of FSD.
• ½” NPT (M) standard.
• Thermo well Required
• Accuracy - +/- 1% of FSD
• Micro pointer adjustment for zero.
TEMPERATURE INSTRUMENTATION
Mercury filled, Gas Filled Thermometer or
Temp. Gauge :
• For Remote Mounted Temp. Gauge.
• Inert Gases are used.
• Range -200 to 800 DegC
• Thermo well Required
• Accuracy - +/- 1% of FSD and above
TEMPERATURE INSTRUMENTATION
Bimetal Temp. Gauge :
TEMPERATURE INSTRUMENTATION
Gas Filled Capillary Temp. Gauge :
TEMPERATURE INSTRUMENTATION
Different Types of Temp. Gauge :
TEMPERATURE INSTRUMENTATION
Bimetal Temp. Gauge :
TEMPERATURE INSTRUMENTATION
Thermo well :
TEMPERATURE INSTRUMENTATION
Flanged Thermo well :
TEMPERATURE INSTRUMENTATION
Different Thermo well :
TEMPERATURE INSTRUMENTATION
Temperature switches are also available
Thermo well material shall be min. SS316, can
be available in SS316L, Hastelloy.
Connection shall be 1.5” 300#RF ANSI Flange
standard.
Can be available in Threaded, welded also.
Based on requirement & application.
TEMPERATURE INSTRUMENTATION
Temperature Element :- RTD, Thermocouple
RTD :- Resistance Temperature Detector
• PT-100, PT-1000, CU-2000
Principle :- Change in Resistance is directly
proportional to Temperature.
3 wire RTD
4 wire RTD
RTD Assembly
Thermocouple
Thermocouple :
• K-type normally used.
• E Type, J type, R Type, S Type, T type.
• Principle : Works on Seebeck Effect, which is
when two dissimilar metal junction heated, a
potential difference is developed at other end.
Thermocouple
Thermocouples Types
• E Type , Chromel (+ve) – Constantan(-ve),
Recommended Range -184 to 982 DegC
• J Type , Iron (+ve) – Constantan(-ve),
Recommended Range 0 to 815 DegC
• K Type , Chromel (+ve) – Alumel (-ve),
Recommended Range -184 to 1260 DegC
Thermocouples Types
• R Type , Pt87-Rh13(+ve) – Platinum(-ve),
Recommended Range 0 to 1648 DegC
• S Type , Pt90-Rh10 (+ve) – Platinum(-ve),
Recommended Range 0 to 1760 DegC
• T Type , Copper (+ve) – Constantan (-ve),
Recommended Range -184 to 398 DegC
TEMPERATURE INSTRUMENTATION
RTD/TC:-
TEMPERATURE INSTRUMENTATION
Thermo well with Temp. Element
TEMPERATURE INSTRUMENTATION
Installed thermo well in pipe line :-
TEMPERATURE INSTRUMENTATION
Installed thermo well in pipe line :-
TEMPERATURE INSTRUMENTATION
Temperature Transmitter:-
CONTROL VALVE
(Presented by G D Rathi)
Section 1
50
PSIG
TANK
PCSupply
Supply
Steam
P1 = 75-100 psig
Positioner
3-15 PSIG
What is a control valve?
Typical Pressure Control Loop
Pneumatic
50
PSIG
TANK
PIT
Supply
Steam
P1 = 75-100 psig
Positioner
Analog
Electro-Pneumatic
Control Signal4-20mA
Process Variable4-20mA
50
PSIG
TANK
PIT
Supply
Steam
P1 = 75-100 psig
Positioner
Digital
Control Signal
Process Variable
Bi-directional Digital communication
What is control valve?
• It is one of the final control elements
– Controls/Regulates flow rate of fluid
– Controls compressable(gas) and non-
compressable(liquid) fluids
– The other final control elements are ID fan/FD fan
dampers, VFD(for pump sped control), over head
water tank float valve
– Based on the application control loops are
functionally termed as Flow control valve(FV), Level
control valve(LV),Pressure control valve(PV),
Temperature control valve(TV )
CONTROL VALVE
CONTROL VALVE
• What are the various types of control
valves
- Globe: very widely used for most of
applications
- Butterfly: low pressure drop and for sizes
more than 4” generally
- Ball: tight shut off and on/off applications
- Diaphragm: corrosive and slurry services
CONTROL VALVE
• What are various parts of control valve?
- Body : consists of trim (closure member)
- Bonnet: The portion of the valve which encloses the pressure retaining parts such as packing rings, stem
- Yoke: the connecting part between body and Actuator
- Actuator: where Instrument air acts for operating the valve
- Positioner: the component which positions the valve stem at required position based on the control signal
- Travel limit switches: which gives feed back signal of valve travel
The device that positions the throttling
element inside the valve body
Lever
Yoke
Stem (Piston Rod)
Travel Indicator
Body Subassembly
Throttling Element
Stem Connector
Diaphragm
Piston
CONTROL VALVE
DIAPHRAGM
CASINGS
LOCK NUT
STEM CONNECTOR
SPRING ADJUSTER
ACTUATOR STEM
ACTUATOR
SPRING
BONET FLANGE
VENT
SCALE
STUFFING BOX
YOKE
DIAPHRAGM
GLAND STUDS
SPRING SEAT
DIAPHRAGM
PLATE
INPUT SIGNAL
INDICATOR
Pneumatic single spring diaphragm actuator
CONTROL VALVE
• Linear motion control valves
- Globe
- Gate
- Diaphragm
- Pinch
• Rotary motion control valves
- Ball
- Butterfly
- Plug
CONTROL VALVE
• Basic relation of Flow rate & Pressure drop
- Flow rate is proportional to square root of pressure drop
- The proportionality between flow rate and square root of pressure drop holds true only for fully turbulent fluid behavior
CONTROL VALVE
• Steps for sizing of control valve
• Inputs
- Fluid status(liquid/gas/steam)
- Flow rate maximum/normal/minimum
- Pressure drop
- Density /specific gravity of fluid
- Temperature of fluid
- Pipe line size
CONTROL VALVE
• Valve flow coefficient, Cv
- Number of U.S gallons per minute of water
that will pass through a given flow
restriction with a pressure drop of one psi
- a Cv of 12 means the control valve at full
open position passes 12 US gallons of
water per minute with one psi pressure
drop across it. It is a capacity index.
CONTROL VALVE
• Calculating Cv for liquid flows
- Cv = (q/N1*Fp)*√Gf/p1-p2
• For gas flow
- Cv = q/N7*Fp*p1*γ*√GgT1Z/x
Cv= valve flow coefficient
q= volumetric flow rate
N= numerical constant
Gg= gas specific gravity
Gf=specific gravity at flowing temp
T1=absolute inlet temperature
Fp=piping geometry
factor
p1=upstream pressure
p2=downstream pressure
γ = gas expansion factor
x = pressure drop ratio dp/p1
Z = gas compressibility factor
CONTROL VALVE
• Control valve size should typically not be less than half size of the line size where it is installed i.e in a 6” line CV should not be 2”. It can be 6” or 4” or 3” based on Cv calculated.
• Using line size valve with reduced trims following advantages
- saves cost on reducers( However, the cost of reducers vs CV cost to be evaluated before making this conclusion)
- permits increasing future throughput
- permits the design of piping system before final CV selection
SIZING CONTROL VALVESFactors to be considered
–Liquid sizing
– Understanding Bernoulli’s equation
– Choked Flow
– Pressure recovery coefficient
– Cavitation
– Flashing
– Noise
– Gas sizing
– Trim characteristics
– Material selection
– Stelleting
– Pipe velocity limitations
– Trim exit velocity limitations
SIZING CONTROL VALVESLiquid service – pressure recovery curve
P1 Inlet Pressure
P2 Outlet Pressure
V1 Inlet Velocity
PVc
VVc
Valve inlet Valve outlet
Pv Vapour Pressure
Single Stage LetdownP1 Inlet Pressure
SIZING CONTROL VALVES
Flashing service
P1
P2
V2V1
PVc
VVc
Outlet Velocity
Outlet Pressure
Valve inlet Valve outlet
Pv Vapour Pressure
Inlet Velocity
Inlet Pressure
PVc
SIZING CONTROL VALVESCavitating service
P1
P2
V2V1
PVc
VVc
Outlet Pressure
Valve inlet Valve outlet
Pv Vapour Pressure
Inlet Velocity
Inlet Pressure
SIZING CONTROL VALVESCavitation and Flashing
→ Cavitation & Flashing are liquid phenomena
→ There is bubble formation when the static pressure of the fluid falls below
the vapour pressure.
→The bubbles formed collapse when the static pressure increases above the
vapour pressure. This is cavitation.
→The bubbles formed are carried downstream if the outlet pressure is less
than vapour pressure. This phenomena is flashing.
→Both Cavitation and Flashing can cause excessive erosion on Trim parts,
body and downstream pipe.
→Cavitation can be fully eliminated by offering suitable trim but not flashing.
→Low recovery valves are less prone for cavitation
SIZING CONTROL VALVE
Cavitation service: solution
• Reduction of operating temperature
• Reduction in differential pressure drop
• Location of the valve
• Selecting Valve with low recovery
• Selecting multistep valve
• Cascading
SIZING CONTROL VALVECavitation service: solution
CONTROL VALVE
• Control valve basic characteristics
The relation between flow rate through a
valve and the valve travel
- Equal %
- Linear
- On/off
CONTROL VALVE - Characterstics
SIZING CONTROL VALVES
Trim characteristics100
80
60
40
20
020 40 60 80 100
Flo
w r
ate
Quick opening
Linear
Equal percentage
CONTROL VALVE
• How to select required valve characteristic
- select =% if the system decreases with
increasing valve load
- if the pressure drop is varying i.e not
constant pressure drop
- Typical applications with above conditions
are Pressure control and nonlinearised
flow control
CONTROL VALVE
• Linear characteristic selected for following
applications
- pressure drop is constant
Typical applications are:
- level control
- pump minimum flow bypass control
- split range
CONTROL VALVE
• Quick opening characteristic
- typically selected for On/off valve
applications
- Depressurising applications
CONTROL VALVE
• Input data for selecting proper MOC
- Design pressure & temperature
- Piping specifications
CONTROL VALVE
• Some special applications
- Coker valves used in DCU plant
- As the coke is very turbid / tendency to solidify at
low temperature valves need special
attention/design to work in these harsh
conditions
- Due to high pressures Motorised actuators are
used instead of conventional pneumatic
- Knife edge valves are used in slurry/pulp
services
SIZING CONTROL VALVE
• Control Valve Leakage
ANSI/FCI 70-2 Test Medium Pressure and temperature
Class II
Class III
Class IV
Class V Water Service DP at 10 to 52deg C
Port dia.Bubbles per
Min.mL per Min.
1 1 0.15
1 - 1/2 2 0.30
2 3 0.45
2 - 1/2 4 0.60
3 6 0.90
4 11 1.70
6 27 4.00
8 45 6.75
Maximum Leakage
0.5% valve capacity at full travel
0.1% valve capacity at full travel
0.01% valve capacity at full travel
0.0005ml/min/psid/in. port dia
Class VI
Service DP or 50 PSID
whichever is lower at 10 to
52deg C
Water / Air
Service DP or 50 PSID
whichever is lower at 10 to
52deg C
Air
FF LOOP (DCS)
Control Valve
Globe Control ValveRotary Control Valve
Control Valve
CONTROL VALVE
COMPONENTS
• Control Valve Accessories- Positioners
- Position Transmitters
- Limit Switches
- Solenoid Valves
- Air Filter Regulators
- Lock-up relays
- Volume Tanks
• Positioners
- Pneumatic
- Electro pneumatic
- SMART / HART Type
- Foundation Fieldbus Digital Positioners
CONTROL VALVE ACTUATORS
Actuator Types
Piston Diaphragm
Linear Rotary
Pneumatic Hydraulic Electric
Actuators
CONTROL VALVE
CONTROL VALVE
COMPONENTS
DIFFERENT TYPES OF CONTROL VALVE
Globe valve
Angle valve
3-way valve
Ball valve
Butterfly valve
V-ball valve
CONTROL VALVE
CONTROL VALVE
CONTROL VALVE
INSTALLATION PRACTICESPERFORMANCE
• Max straight run in inlet pipe – A good thumb rule -10 to 20 D
• Allow straight run in outlet pipe – 3 to 5 D
straight run in inlet pipe – steady inlet flow – steady & repeatable
flow
• Location of PG &
Location of CV with respect to indicator of controlled parameter
4
2
5
4
5
21
3
AVOID AVOID
INSTRUMENTATION
(Presented by G D Rathi)
Boiler Controls
Distillation Column Controls
Boiler Control Loops
Boiler Control Loops
Boiler Control Loops
Boiler Control Loops (3 – Element)
Distillation Column
• Distillation is very common and widely
used for process of separation.
• Used to isolate & purify volatile materials.
• Separates a mixture on the basis of
difference in the composition of liquid and
that of the vapor formed from the liquid.
Distillation Column
• Distillation column is energy separating
agent equilibrium process that uses the
difference is relative volatilities or
difference in relative boiling points of
components to be separated out.
• Most commonly used in oil & Gas
Refinery, Petrochemical & Chemical
plants etc.
Distillation Column Objective
• Column Operating objectives :-
– Operating objectives includes the composition
specification for the top and the bottom product
streams.
– Other Objectives can include increasing throughput,
enhancing column stability, and operating equipment
constraints.
Distillation Column
• Proper instrumentation for distillation
column operation is vital to achieve
maximum product of satisfactory purity.
• Instrumentation is used to solve equations
necessary for proper control of distillation
column.
Distillation Column
• Primary application of instrument & control
in column is to control product purity.
• Secondary application is to minimize
upsets to unit caused by change in
process inputs.
Distillation Column Flow Sheet
Distillation Column Equipments
• Column
• Pre heater
• Condenser
• Accumulator
• Reflux pump
• Re-boiler
Distillation Column Equipments
Distillation Column Equipments
• Reflux System :-
– The overhead vapor leaving column is sent to a
cooler or condenser and is collected as a liquid in
accumulator or receiver.
– A part of accumulated liquid is returned to column
as a reflux.
– The remainder is withdrawn as overhead product
or distillate.
Distillation Column Equipments
• Re-boiler System :-
– The liquid leaving the column bottom is heated in
a re-boiler (A re-boiler is a special type of heat
exchanger used to provide the heat necessary for
distillation).
– Part of this liquid is vaporized and returned into
the column as a boil up.
– The remaining liquid is withdrawn as a bottom
product or residue.
Column Re-Boiler
Variables for Distillation Operation
Distillation Column Controlled
variables• Column Controlled variables :-
– As we know controlled variables can be affected by
several manipulated variables, only one
manipulated variables used to directly affect the
value of controlled variable.
– Minimum following controlled variables for a column
need to be considered.
Distillation Column Control
Configuration
Distillation Column Control
Configuration
Distillation Column Control
Configuration
Distillation Column Control
Configuration
Internals of Column