industry applications series -...

I N D U S T R Y A P P L I C A T I O N S S E R I E S

APPLICATION PAGE

Separation

1. Crude Storage 4

2. Crude Dewatering 4

3. Crude Desalting 5

4. Preflash Drum 5

5. Distillation Column 6

6. Reflux Accumulator 6

7. Column Reboiler 7

8. Solvent Extraction 7

Conversion

9. Catalytic Cracker 8

10. Catalytic Stripper 8

11. Hydrocracking 9

12. Acid Settling Tanks 9

13. Alkylation Tanks 10

14. Catalytic Reformer 10

15. Coking Operations 11

16. Isomerization 11

Treatment

17. Hydrodesulfurization12

18. Chemical Storage 12

Blending

19. Blending Unit 13

20. Finished Products 13

See page 14 for information onrefinery flow controls and leveland flow control applications forrefinery power generation.

20 Leading

Petroleum

RefineryLevel ControlApplications

2

SEPARATION

BLENDINGTREATMENT

An Industry Guide To Level Measurement and Control from Magnetrol®

CONVERSION

3

Application: All unrefined crude oil stored intanks has a percentage of water entrained withinit, and while stored in tanks, separation naturallyoccurs with water collecting at the bottom ofthe tank beneath the oil. The two fluids are verydistinct except for a "black water" or "rag" inter-face layer which is an emulsion of mixed oil andwater. To dewater the tank, water is drawn off ofthe bottom of the tank and is then sent off towater treatment.

Challenges: Level controls designed for inter-face detection will sense the beginning of theoil/water interface during dewatering proceduresand provide feedback to a control system whichwill terminate water draw-off when appropriate.

Application: Upon arrival at the refinery termi-nal, crude oil is pumped into above-ground stor-age tanks with capacities of thousands to mil-

lions of gallons. Raw crude is stored in floating-or fixed-roof tanks field-built to API standards.Tank level measurement by noncontact radarhas gained share over mechanical float typeand servo gauges due to its accuracy, lowmaintenance, no moving parts and fast set-up.

Challenges: Tank level is maintained by valveactuation. By triggering an emergency cutoff,level controls prevent overflows and shut downpumps when level falls below low level. Safety-certified controls may be necessary due tocrude’s low flash point.

1

2

Crude Tanks

CRUDE DEWATERING

CRUDE STORAGE

Crude Tanks

INSTRUMENTATIO

NIN

STRUMENTATIO

N

s Point Level:

Model A15Displacer-Actuated LevelSwitch

s Continuous Level:

Pulsar™ Model R86Pulse Burst RadarTransmitter

s Continuous Level:

Eclipse® Model 706Guided Wave RadarTransmitter with 7y1Single Flexible CableProbe

s Point Level:


s Continuous Level:

ECLIPSE Model 706Guided Wave RadarTransmitter

s Continuous Level:

E3 Modulevel®

Displacer-ActuatedTransmitter or Kotron®

Model 805 Smart RFCapacitanceTransmitter

4

PREFLASH DRUM

CRUDE DESALTING

Application: Located in the preheat train of thedistillation column, a preflash drum system sep-arates the vapors generated by preheatingbefore entering the heater or main column. Thisprevents higher heater firing or pressure dropsand reduces vapor loading of the column toavoid flooding.

Challenges: Preflash drums create moderatefoam that can affect measurement accuracy ofliquid levels and decrease distillate productionin the atmospheric column. Too low of a pre-flash drum level will cause pump cavitation ofthe flashed crude. Too high of a level will causeliquid carryover to the distillation column.

Application: Inorganic chlorides, suspendedsolids, and trace metals found in untreated crudemust be removed by chemical or electrostaticdesalting. This reduces the risk of acid corrosion,plugging, fouling and catalyst poisoning indownstream units. Measurement of the oil/waterinterface in the desalter is crucial in separatingthe cleansed crude from contaminants.

Challenges: Coating and build-up on probesmay create interface measurement errors.Instruments susceptible to electrostatic gridinterference may require special filters. Interface-dedicated level transmitters fitted with quick-dis-connect probes provide optimum performancewhile reducing cleaning and maintenance time.

4

3

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Desalting Tanks

Preflash Drum

s Point Level:


s Continuous Level:

ECLIPSE Model 706Guided Wave RadarTransmitter

s Continuous Level:

E3 MODULEVELDisplacer-ActuatedTransmitter

s Point Level:

Series 3Float-ActuatedExternal CageLevel Switch

s Continuous Level:

E3 MODULEVELDisplacer-ActuatedTransmitter; or ECLIPSEModel 706 GuidedWave Radar Transmitter

s Visual Indication:

Atlas™ or Aurora®

Magnetic Level Indicatorscan be supplied withswitches or transmitters

5

Application: A heat exchanger removes vaporfrom the upper parts of the fractionator, cools itto a liquid, and pumps it into an accumulator(reflux drum). Reflux pumps then draw liquidfrom the bottom of the accumulator and pumppart of it back (reflux) where it is reintroduced at a lower point in the column. This refluxingprocess improves separation in the column byassuring sufficient downward liquid flow meet-

ing the rising vapor.

Challenges: Accurate and reliable level monitor-ing and control is necessary for the refluxaccumulator to serve as a distribution point forreflux and distillate, and prevent excessivereflux from returning back to the tower.

Application: Following desalination, crude oilenters the distillation column where fractionaldistillation separates hydrocarbons into sepa-rate streams, cuts or fractions. For optimumoperation of the distillation column, level con-trols must contend with occurances of foaming,bubbling and moderate-to-high temperatures.

Challenges: Sight glasses and displacer sys-tems mounted in external chambers have tradi-tionally provided distillation level measurement.Today, radar retrofitted in these existing cham-bers is gaining popularity due to radar’s lessdemanding maintenance schedule and ease ofretrofit. High product temperatures necessitatetemperature-tolerant level sensors.

5

6 REFLUX ACCUMULATOR

DISTILLATION COLUMN

Fractional Distillation

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Reflux Accumulator

s Continuous Level:

E3 MODULEVELDisplacer-ActuatedTransmitter orECLIPSE Model 706Guided Wave RadarTransmitter

s Continuous Level:



ATLAS or AURORAMLIs can be suppliedwith switches or trans-mitters


ATLAS or AURORAMLIs can be suppliedwith switches or trans-mitters

s Point Level:


s Point Level:


6

SOLVENT EXTRACTION

COLUMN REBOILER

Application: The heavy fraction remainingfollowing the distillation of crudes is calledpetroleum resids. A variety of solvent-extractionprocesses yield deasphalted oil (DAO) fromthese resids. These oils serve as downstreamfeedstocks for catalytic crackers and hydro-crackers. Depending upon the system configu-ration, level monitoring of the separator, pre-flash, stripper and hot oil phases may includesurge and flash drums, separators and strippers.

Challenges: Level control is critical becauseinterface level control of the separator feeds theflash drum, whose level feeds the stripper, etc.Application extremes include high temperatures,high pressures, and the presence of steam.

Application: A heat exchanger positioned nearthe bottom of the distillation column re-heatsand vaporizes liquid and reintroduces the vaporseveral trays higher. This improves separationby introducing more heat into the column. Foreffective functioning of the reboiling process,

level monitoring of the reboiler is required.

Challenges: In some steam reboilers, the levelmust be controlled so that only a percentage oftubes are covered. This allows a control schemeto regulate the heat transfer in the reboiler bycontrolling the percentage of the reboiler tubescovered by liquid. This is a critical control loopas heat transfer into the liquid is a strong func-tion of the percentage of tubes covered.

8

7

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Reboiler

s Continuous Level:



ATLAS or AURORAMLIs can be suppliedwith switches ortransmitters

Flash Tank

s Point Level:

Series 3 Float-Actuated ExternalCage Level Switchor Tuffy® II Float-Actuated Switch

s Continuous Level:




s Point Level:

Series 3 Float-Actuated ExternalCage Level Switch

7

Application: Variations in cat cracking includeSelective Component Cracking (SCC) forpolypropylene production, a two-vessel andexternal-reactor design for processing heavyresidue feeds, and a UOP process for convertinggas oils and resid feedstocks. All crackersemploy a steam stripper to remove hydrocar-bons entrained in the spent catalyst.

Challenges: Stripper level control allows suffi-cient residence time for stripping steam to dis-place hydrocarbons for recovery. It also main-tains sufficient pressure to keep air in the regen-erator from reverse flow into the reaction system,thereby causing a hazard. A waste heat recoverysteam drum would also require monitoring.

Application: The Fluid Catalytic Cracking Unit(FCCU) cracks heavy, low-value feedstocks intohigh-value, lighter molecular weight hydrocar-bons which are blended to finished products. Acracker can produce a wide variety of yield pat-terns by operating in either Gasoline, Distillateor LPG modes.

Challenges: Catalytic crackers utilize a reactorand a catalyst regenerator with connecting ris-ers where the reactions take place. Level con-trollers are often positioned on the first stageregenerator and at the top of the reactor. Levelmeasurements involve fluidized solids levels athigh temperatures. Conventional measurementtechniques can be subject to plugging.

9

10

CATALYTIC CRACKER

CATALYTIC STRIPPER

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Regenerator

Stripper

s Continuous Level:

E3 MODULEVELDisplacer-ActuatedTransmitter

s Continuous Level:

E3 MODULEVELDisplacerTransmitter orECLIPSE Model 706Guided Wave RadarTransmitter


ATLAS or AURORAMLIs can be suppliedwith switches or transmitters

s Point Level:

Series 3 Float-Actuated ExternalCage LevelSwitch or B40Float-ActuatedLevel Switch

8

HYDROCRACKING

ACID SETTLING TANKS

Application: Heavier feedstock difficult toprocess by cat cracking or reforming can beconverted by hydrocracking. By combiningcatalytic cracking and hydrogenation to crackfeedstock in the presence of hydrogen, hydro-cracking produces gasoline and distillate blendingstreams. About a dozen different hydro-crackingprocess schemes are in current use.

Challenges: Level controls for the catalyststripper, separator liquid and flash drum liquidmust contend with severe process conditions tomaintain optimum operation of the hydrocracker.These conditions include elevated temperaturesand pressures, the presence of steam and highpressure hydrogen, and aggressive corrosives.

11

12

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Application: Alkylation is a combining processthat creates alkylate, a premium, high-octaneblending stock. A large acid settler tank withinthe unit allows for separation of the acid/hydro-carbon emulsion created in the reactor. Sightglasses have traditionally measured settler level,but these are susceptible to plugging and requirediligent flushing at regular intervals.

Challenges: Interface level control of the settleris required. Product/acid cross-contaminationcauses overall efficiency problems and can resultin hazardous conditions. Inaccurate settler levelindication is a frequent cause of physical acidcarryover in the reactor effluent. Release of acidcan cause extreme hazards to both process andpersonnel.

Hydrocracking Unit

Settling Tank

s Continuous Level:


s Point Level:


s Continuous Level:

E3 MODULEVELDisplacer-ActuatedTransmitter or ECLIPSEModel 706 GuidedWave Radar Transmitter




ATLAS or AURORAMLIs can be supplied with switches or transmitters

s Point Level:

Series 3 Float-Actuated ExternalCage Level Switchor B40 Float-Actuated LevelSwitch

9

Application: Catalytic reforming upgrades low-octane naphthas into high-octane gasolineblending components called reformates. Usingheat and pressure with platinum catalysts torearrange hydrocarbon molecules, this processconverts low-octane gasoline fractions intopetrochemical feedstocks and higher octanestocks suitable for finished gasoline blending.

Challenges: A hydrogen-rich gas stream isremoved from the separator for recycling. Liquidproduct monitored for level at the bottom of theseparator is sent to a stabilizer. Where stabilizerfouling has occurred due to the formation ofammonium chloride and iron salts, a monitoredwater wash system should also be included.

Application: Storage and wash vessels in thealkylation unit include those for fresh anddepleted acid and water, an acid analyzer set-tling pot, and a number of wash tanks. Causticwashes neutralize free acid carried over fromthe reaction zone and neutralize alkyl sulfates inthe net effluent. Water washes decomposeremaining esters and remove caustic and saltthat might have carried over from the causticwash.

Challenges: Interface level control in causticand water washes prevents corrosion and foul-ing of the deisobutanizer and other downstreamunits. Levels rising above high set points cancause carryover of caustic or water, while toolow levels can cause hydrocarbon carryunder.

CATALYTIC REFORMER

ALKYLATION TANKS 13

14

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Wash Tanks

s Continuous Level:

E3 MODULEVELDisplacer-Actuated Transmitter orECLIPSE Model 706Guided Wave RadarTransmitter or PULSARR86 Radar Transmitter

s Point Level:

Echotel® Models910, 961 or 962Ultrasonic LevelSwitches or ModelA15 Displacer-Actuated Switch


ATLAS or AURORA MLIscan be supplied withswitches or transmitters

s Continuous Level:

E3 MODULEVEL Displacer-Actuated Transmitter orECLIPSE Model 706 GuidedWave Radar Transmitter orPULSAR Model R86 RadarTransmitter


ATLAS or AURORAMLIs can be supplied withswitches or transmitters

Photo of Catalytic Reformer courtesy of CB&I

s Point Level:

Series 3 Float-Actuated ExternalCage LevelSwitch

10

ISOMERIZATIONApplication: Isomerization in a variety ofprocess configurations alters the arrangementof atoms to convert normal butane into isobu-tane, and normal pentane and hexane into high-octane gasoline components. Isomerization issimilar to catalytic reforming in that the hydro-carbon molecules are rearranged, though iso-merization only converts normal paraffins toisoparaffins.

Challenges: Near the end of the process, reactoreffluent is cooled and separated into the liquid-product isomerate and a recycle hydrogen-gasstream. Isomerate is caustic-washed and water-washed, acid stripped, and stabilized beforegoing to storage. Stabilizer bottoms and washtanks require level monitoring.

COKING OPERATIONSApplication: Coking is the final means of con-verting the heaviest products of atmosphericand vacuum distillation. Feed is heated andcracked into light gases, gasoline blendstocks,distillates, and gas oil. Level applications fordelayed and continuous (contact or fluid) cokinginclude the fractionator, light gas oil stripper,steam, condensate, blowdown and settlingdrums, and vent gas knockout drums.

Challenges: Process conditions that levelinstrumentation must contend with include hightemperatures, high pressures, foaming, andsteam. An interface level gauge in drums thatare susceptible to foaming will help avoid foam-over and increase coke drum output.

15

16

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Coking Unit

Isomerization Unit

s Continuous Level:



ATLAS or AURORAMLIs can be suppliedwith switches or transmitters



s Continuous Level:


s Point Level:


s Point Level:

Series 3 Float-Actuated ExternalCage Level Switchor B40 Float-Actuated LevelSwitch

11

Application: From acids to water treatmentadditives, a wide array of chemicals are storedat a refinery in vessels that range in size fromplastic totes to large steel tanks. Chemicalssuch as sulfuric and hydrochloric acid, sodiumhydroxide, liquid catalysts, blending additivesand water treatment chemicals are essential toa refinery’s day-to-day operation.

Challenges: Liquid solution storage and daytanks require stringent level monitoring toensure ongoing chemical processing. The natureof the chemical, the geometry of the holdingvessel, and the presence of mixers or otherhardware will determine the most suitable leveltechnology for the storage or feed application.

Application: Catalytic Hydrotreating treatshydrocarbon liquids in the presence of hydro-gen. This process removes 90% of the sulfur,nitrogen, oxygen, and metals from feedstocks.Hydrotreating can also provide hydrodearomati-zation (HDAr), heavy diesel hydrocracking(HDHDC), dewaxing, and performance enhance-ments of pyrolysis gasoline and diesel.

Challenges: Hydrotreatment will necessitatelevel indication of liquid/gas separators andwater wash tanks. Level devices suited for hightemperatures and pressures are essential inremoving contaminants that can have detrimen-tal effects on equipment, catalysts, and thequality of the finished product.

CHEMICAL STORAGE & FEED

HYDRODESULFURIZATION

Chemical Storage

17

18

INSTRUMENTATIO

NIN

STRUMENTATIO

N

Hydrodesulfurization Unit

s Continuous Level:


s Point Level:

ECHOTEL Models910, 961 or 962Ultrasonic Switchesor TUFFY II Float-Actuated Switch

s Continuous Level:

PULSAR Model R86Radar Transmitter orECLIPSE Model 706Guided Wave RadarTransmitter with InsulatedSingle Rod Probe


ATLAS or AURORAMLIs can be supplied with switches ortransmitters


ATLAS or AURORAMLIs can be supplied with switches ortransmitters

s Point Level:

Series 3 Float-Actuated ExternalCage LevelSwitch or B40Float-ActuatedLevel Switch

12

Application: Finished refinery products storedin tanks with capacities that often exceed100,000 gallons are motor gasoline, jet fuel,diesel fuel, fuel oils, and LPG. Marketed prod-ucts also include feedstocks for textiles, tires,pharmaceuticals and plastics.

Challenges: Tank monitoring uses buoyancy,pressure, servo-driven, and radar. Tanks may beprovided with automatic overflow control andalarm systems. Automated tank gauging net-works with proprietary protocols are a vital partof tank farm architecture. Today, thousands oftanks can be linked in a network offeringenhanced data acquisition, field calibration and remote diagnostics.

FINISHED PRODUCT STORAGE

Application: Mixing finished gasoline requireslevel monitoring of blending stocks, in-lineblending, additive storage, dilution systems andinjection systems. Blend stocks are straight-rungasoline, alkylate, reformate, benzene, tolueneand xylene. Additives include octane boosters,metal deactivators, anti-oxidant and knockagents, gum and rust inhibitors, and detergents.

Challenges: Level is normally measured only forinventory control and, in some cases, custodytransfer. The precision of level indication that isrequired varies. If level is used only for internalinventory control, a less accurate measurementcan be used. If level is used for custody transfer,highly accurate measurements are required.

Finished Storage

BLENDING OPERATIONS 19

20

INSTRUMENTATIO

N

Blending Stocks

s Point Level:

ECHOTEL Models910, 961 or 962Ultrasonic LevelSwitches

s Continuous Level:

ECLIPSE Model 706Guided Wave RadarTransmitter or PULSARModel R86 RadarTransmitter



s Point Level:


s Continuous Level:

PULSAR Model R86Radar Transmitter orECLIPSE Model 706Guided Wave RadarTransmitter



INSTRUMENTATIO

N

13

Application: The vast piping systems withintoday’s refineries transport hydrocarbongas/vapor streams, light liquid gas/liquidstreams, heavier liquid streams, water, andsteam throughout the refinery. Certified, reliableand accurate flow measurement is essential fora refinery’s safe and efficient operation.

Challenges: Flow alarms and continuous flowcontrols monitor product streams, signal no-flowconditions caused by plugging or valve closure,and provide a defense against pump cavitation.Pumps operating in a reduced or no-flow condi-tion can overheat and rupture the pump’s sealand cause a dangerous deviation in processpressure and temperature.

REFINERY FLOW APPLICATIONSIN

STRUMENTATIO

N

POWER GENERATIONPower Generation: Many petroleum refineries incorporate powergenerating plants into their refinery operations. These include powerstations with coal-fired boilers and gas-fired co-generation plants.

Because a thorough discussion of power generation applications isbeyond the scope of this brochure, we invite you to log onto

Visit www.magnetrol.com and download the pdf of the MAGNETROLPower Generation brochure. This 16-page brochure describes 20essential level control applications in power generation—most ofwhich are applicable to today’srefinery operations.

s Continuous Air or Gas Flow:

THERMATEL Model TA2Thermal Dispersion MassFlow Transmitters

s Flow Alarm:

Thermatel® Model TD2Thermal DispersionFlow Switch

s Pump Protection:

THERMATEL Model TD2Thermal DispersionFlow Switch

14

efinery professionals know that great gasoline can

only originate within a great process scheme. And

that especially means process controls that deliver reliable

service in the most demanding applications. Acquiring level

and flow controls of this high calibre is why so many instru-

ment professionals turn to MAGNETROL.

Our buoyancy products were introduced to refinery

service in 1932. Later we were among the first to apply

thermal dispersion, ultrasound, capacitance and other elec-

tronic technologies to refinery challenges. More recently we

pioneered ECLIPSE Guided Wave Radar and PULSAR Pulse

Burst Radar to bring customers the leading-edge in level

transmitters—the kind that balance sophisticated sensing

technology with simplified ease-of-installation and operation.

MAGNETROL also offers a wealth of application engi-

neering know-how and a worldwide service network that’s

second to none. And that’s the difference between just

buying an instrument and partnering with a world-class

level and flow specialist.

Contact your MAGNETROL sales representative today

to learn how our products can not only help you create

great gasoline, but will actually increase the profitability of

your refinery’s operation. n

15

Worldwide Level and Flow Solutions

R

SM

Where Great FuelGets Its Start.

AN INDUSTRY GUIDE TO LEVEL MEASUREMENT AND CONTROL FROM MAGNETROL

Other industry and special application brochures from MAGNETROL include:

• Chemical

• Crude Oil Processing

• Flue Gas Desulfurization

• Food & Beverage

• Interface Level Measurement

• Life Science

• Mass Flow Measurement

• Modular Skid Systems

• Natural Gas Processing

• Nuclear Power

• Power Generation

• Pulp & Paper Mills

• Renewable Energy

• Steam Generation

• Tank Bridle Level Measurement

• Tank Overfill Prevention

• Understanding Safety Integrity Level (SIL)

• Water & Wastewater

PLEASE NOTE: The instruments recommended in these brochures are based on field experience withsimilar applications and are included as a general guide to level and flow control selection. Becauseall applications differ, however, customers should determine suitability for their own purposes.

Magnetrol & Magnetrol logotype, Aurora, Echotel, Eclipse, Modulevel,

Pulsar, Thermatel, and Tuffy are registered trademarks of Magnetrol International, Incorporated.

Copyright © 2018 Magnetrol International, Incorporated

Bulletin: 41-176.3 • Effective: April 2018

CORPORATE HEADQUARTERS705 Enterprise Street • Aurora, Illinois 60504-8149 USA

Phone: 630.969.4000magnetrol.com • [email protected]

EUROPEAN HEADQUARTERSHeikensstraat 6 • 9240 Zele, Belgium

Phone: 052 45.11.11

Find your local representative at magnetrol.com

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