INDUSTRY APPLICATIONS SERIES · 2019-01-04 · O ne hundred years ago, electric power was over 20 cents a kilowatt-hour— more than twenty times today’s cost. Back then electricity

A Guide to Level Instrumentation for Power Generating Plants

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

POLLUTION

CONTROL

SYSTEM

RAW COAL

TURBINES

STEAM

BOILER

CONDENSER

SO2REMOVAL

COAL STORAGE . . . . . . . . . . . . .6

NATURAL GAS SEPARATOR . . . .6

FUEL OIL STORAGE . . . . . . . . . .7

AMMONIA STORAGE . . . . . . . . . .7

CONDENSER HOTWELL . . . . . . .8

CONDENSATE STORAGE . . . . . .8

1 DEAERATOR . . . . . . . . . . . . . . . . .9

FEEDWATER HEATERS . . . . . . .10

STEAM DRUM . . . . . . . . . . . . . .10

CONDENSATE DRIP LEGS . . . .11

BOILER BLOWDOWN TANK . . .12

FLASH TANK . . . . . . . . . . . . . . . .12

Level Controls in a Coal-Fueled Plant

1

PU

LV

ER

IZE

R

COAL

SILO

COMBUSTION

FUEL

SYSTEM

POST

COMBUSTION

SYSTEM

2

3

4

5

5

6

6

7

8

9

10

11

78

KEY LEVEL APPLICATION PAGE

STEAM

GENERATING

SYSTEM

2

3

IGNITION

FUEL

STORAGE

9

1211

4

10

12

KEY LEVEL APPLICATION PAGE

2

WATER TREATMENT

GENERATOR

POWER

CONVERSION

SYSTEM

CIRCULATING

WATER

SYSTEM

SOURCE WATER . . . . . . . . . . . .13

DEMINERALIZATION . . . . . . . . .14

MAKE-UP WATER . . . . . . . . . . . .14

SERVICE WATER . . . . . . . . . . . .15

OPEN SUMPS . . . . . . . . . . . . . .16

COOLING TOWER . . . . . . . . . . .16

LUBRICATION OIL TANK . . . . . .17

WATER WASH TANK . . . . . . . . .17

COOLING TOWER

13

14

15

16

17

18

Please Note: The level instruments recommended inthis guide are based on field experience with similarapplications and are included as a general guide tolevel control selection. Because all applications differ,customers should determine suitability for their ownpurposes.

13

14

1516

17

18

KEY LEVEL APPLICATION PAGE KEY LEVEL APPLICATION PAGE

1920

19

20

3

GAS TURBINE

CONDENSER

Level Controls in a Combined-Cycle Plant

STEAM TURBINE

HRSG

HEAT RECOVERY

STEAM GENERATOR

FUEL

9

5

6

78


3

POST

COMBUSTION

SYSTEM

COMBUSTION

FUEL

SYSTEM

STEAM

GENERATING

SYSTEM

NATURAL GAS SEPARATOR . . . .6

FUEL OIL STORAGE . . . . . . . . . .7

AMMONIA STORAGE . . . . . . . . . .7

CONDENSER HOTWELL . . . . . . .8

CONDENSATE STORAGE . . . . . .8

DEAERATOR . . . . . . . . . . . . . . . . .9

FEEDWATER HEATERS . . . . . . .10

HRSG DRUM . . . . . . . . . . . . . . .10

CONDENSATE DRIP LEGS . . . .11

FLASH TANK . . . . . . . . . . . . . . . .12

2

3

4

5

6

7

8

9

10

11

2

41110

POLLUTION

CONTROL

SYSTEM

4

WATER TREATMENT

GENERATOR

POWER

CONVERSION

SYSTEM

CIRCULATING

WATER

SYSTEM

SOURCE WATER . . . . . . . . . . . .13

DEMINERALIZATION . . . . . . . . .14

MAKE-UP WATER . . . . . . . . . . . .14

SERVICE WATER . . . . . . . . . . . .15

OPEN SUMPS . . . . . . . . . . . . . .16

COOLING TOWER . . . . . . . . . . .16

LUBRICATION OIL TANK . . . . . .17

WATER WASH TANK . . . . . . . . .17

COOLING TOWER

13

14

15

16

17

18

Please Note: The level instruments recommended inthis guide are based on field experience with similarapplications and are included as a general guide tolevel control selection. Because all applications differ,customers should determine suitability for their ownpurposes.

13

14

1516

17

18


2019

19

20

5

One hundred years ago, electric power

was over 20 cents a kilowatt-hour—

more than twenty times today’s cost.

Back then electricity was used primarily

in cities for lighting streets and powering streetcars.

The cost of electric power was well beyond the

means of most families, and even rudimentary

appliances were absent from American homes.

But the 20th century brought Power to the

People through improved power-generating technol-

ogy. By century’s end, affordable electricity was

available to all Americans.

As the power industry matured, a Chicago

company that first marketed its level controls for

steam boilers in 1932 would grow along with it. The

young firm would become Magnetrol® International,

Incorporated, and its people would build a worldwide

reputation for durable controls that were able to

withstand the stresses that are routinely found in

modern coal-fired or combined-cycle operations.

The power industry is evolving still today—

from a highly regulated, monopolistic industry with

traditionally structured electric utilities to a less reg-

ulated, competitive industry where rates will

become more and more dynamic to reflect the cost

of providing electrical service. Deregulation will also

provide new impetus for improvements in power

generation and allied technologies.

With its introduction of Eclipse® Guided Wave

Radar in 1998, Magnetrol® has brought leading-

edge level control to the power industry at reduced

capital cost. Other recent innovations at MAGNETROL

have advanced the abilities of ultrasonic, thermal

dispersion and air sonar technologies to provide

more accurate and reliable controls while reducing

product operating costs by replacing electro-

mechanical systems with electronic ones. Where

application demands favor buoyancy level controls,

advanced Modulevel® transmitters lead the industry.

MAGNETROL has also re-invented visual indication

technology with its founding of Orion Instruments®

and the introduction of its Magnetic Level

Indicators, or MLIs, in 2001.

The pages ahead serve as an introduction to

MAGNETROL level sensing and control products for

Power Gen applications. To empower your process

with the leading edge, contact your MAGNETROL

representative. ■

Level Controls for Power Generation since 1932.

POWER PIONEER

Magnetrol® products

were selected for

Argonne National

Laboratory’s Boiling

Water Reactor in the

1950s—one of the

earliest experiments

in Nuclear Power

Generation.

Combustion Fuel • Circulating Water • Steam Generation • Particulate Removal • Power Generation

6

Application: Raw coal is delivered to a coalyard in aggregate pieces of approximately 6"that are later reduced in size by a crusher toapproximately 1.5". Enclosed storage ofcrushed coal is common in frigid climates andwhere containment of coal dust is controlled toprotect populated areas. Hoppers and silosstore active and reserve crushed coal prior toits pulverization into the powdered form suit-able for boiler combustion.

Challenges: Some severe power plant acci-dents in years past have been traced to coaldust ignition, and the atmospheres of con-tained coal storage areas are highly congestedwith explosive dust. For safe coal yard opera-tion, explosion proof, air tight level instrumen-tation is absolutely essential.

INS

TR

UM

EN

TA

TIO

N

Application: Natural gas separators removesolid particles and liquids from a continuousgas stream supply. Dust, dirt, sand and pipescale as well as water, natural gas liquids andlight hydrocarbons can be removed. In a typicalsystem, an inlet separator allows particles andliquids to settle out and the gas to rise. Thegas collects at the top of the separator where itis removed by means of a gas compressor. Thecollected particles and liquids are then dumped into a water tank.

Challenges: Liquid level control precisely mod-ulates the amount of water that is drawn off toensure that the level does not rise too high andenter the compressor inlet.

INS

TR

UM

EN

TA

TIO

N

7

COAL YARD STORAGE PLANT AREA:Combustion Fuel

▲ Point Level:

Solitel® Vibrating Rod Level Switchavailable with an Extended RigidProbe up to 100 inches (254 cm) oran Extended Flexible Probe up to65 feet (20 meters)

NATURAL GAS SEPARATOR PLANT AREA: Combustion Fuel

▲ Continuous Level:

ECLIPSE Model 706Guided Wave RadarTransmitter,E3 MODULEVEL orMODULEVEL PneumaticTransmitters

▲ Point Level:

Model B35 ExternalCage Float-ActuatedSwitch, ASME B31.1Construction

▲ Visual Indication:

Atlas™ or Aurora®

Magnetic LevelIndicators can besupplied withswitches or transmitters

Application: Fuel-fed ignitors initiate the boilerflame in coal-fed plants using natural gas oratomized fuel oils such as light grade #2 orheavy grade #6. Natural gas and propane canalso be used. In combined-cycle plants, gas tur-bines often use natural gas and liquid fuel oils asignition fuel. Large gas turbines are designed tooperate alternately or simultaneously with bothgas and liquid fuels. In dual-fuel plants, a FalseStart Tank will temporarily hold diesel fuel afteran unsuccessful attempt to fire the turbine.

Challenges: Crude oils with lower flash pointsrepresent a greater fire hazard and require moreextensive fire protection systems. Switches andtransmitters should be safety certified.

INS

TR

UM

EN

TA

TIO

N

Application: Vaporized ammonia is used incatalytic and noncatalytic reduction systemsfor emissions control. Ammonia is injected intothe flue gas stream and acts as a reducingagent. It is also used to enhance precipitatorefficiency for particulate control. Pure ammoniais stored in a pressure vessel rated for 250 to300 psig. Aqueous ammonia (70 to 80% water)is stored in a tank rated for 25 to 30 psig.Storage requirements for aqueous ammoniaare three to four times that of pure ammonia.

Challenges: Accidental atmospheric release ofpure ammonia vapor can be hazardous, sosafety and environmental measures may berequired which affect the level control selected.

INS

TR

UM

EN

TA

TIO

NFUEL OIL STORAGE PLANT AREA:

Combustion Fuel

▲ Point Level:

Models B10 orB15 Displacer-ActuatedSwitches


ECLIPSE Model 706Guided Wave RadarTransmitter or Pulsar™

Model R86 Pulse BurstRadar Transmitter

AMMONIA STORAGE PLANT AREA:Particulate Removal


ECLIPSE Model 706Guided Wave RadarTransmitter with 7YPCoaxial Probe


ATLAS or AURORAMagnetic Level Indicatorscan be supplied withswitches or transmitters

▲ Point Level:

Model A15Displacer-Actuated Switch


Echotel® Model 300 or 335 Non-ContactUltrasonic Transmitters

8

Application: Steam enters the condenserwhere it cools and condenses into water beforebeing sent to the low-pressure feed-waterheater. The condenser hotwell serves as awater reservoir for the turbine cycle. Whenhotwell level reaches the low point, a valveopens to supply make-up water to the cycle.When hotwell level reaches the high end of thelevel range, a dump valve opens to move thecondensate from the hotwell to a condensate

storage tank.

Challenges: Water loss in the turbine cycledue to leakage, steam venting or other usagedepletes make-up water. Level control in thehotwell ensures adequate make-up water issupplied to the cycle or diverted to storage.

INS

TR

UM

EN

TA

TIO

N

Application: When the condenser hotwell levelreaches the high point, a dump valve opens todrain excess condensate from the hotwell to acondensate storage tank. When loss of con-densate from the turbine cycle is reflected in alow level in the hotwell, a make-up valve opensin the storage tank to supply make-up water to the condenser hotwell.

Challenges: Proper functioning of the liquidlevel control in the condensate storage tankensures the proper supply of make-up water.

INS

TR

UM

EN

TA

TIO

N

CONDENSATE STORAGE PLANT AREA:Steam Generation

CONDENSER HOTWELL PLANT AREA: Steam Generation

▲ Point Level:

Model B40Float-ActuatedSwitch


ECLIPSE Model 706Guided Wave RadarTransmitter,E3 MODULEVELor MODULEVELPneumatic Transmitter




ECHOTEL Models300 or 335Non-ContactUltrasonicTransmitters

▲ Point Level:

Models B10 orB15 Displacer-ActuatedSwitches


ECLIPSE Model 706Guided Wave RadarTransmitter or PULSARModel R86 PulseBurst RadarTransmitter

9

Application: The deaerator is an open-facedwater heater which removes non-condensablegases from the feedwater. In addition to thecondenser hotwell, the deaerator's storagetank is the remaining reservoir in the turbinecycle. Positioned below the deaerator andbefore the boiler feed pumps, the deaeratorstorage tank serves as a surge tank for theboiler feedwater. Tank level is often controlledby a control valve on the condensate supplyline to the deaerator.

Challenges: Pressure fluctuations are exten-sive in the deaerator storage tank and result inflashing. Level controls must contend with thetank's fluctuating temperatures and pressures.

INS

TR

UM

EN

TA

TIO

N

Application: Placed along super heated steamlines, condensate drip legs (or drip traps) collectparticles of moisture and drain off the accumu-lated condensate. Employed as a preventativemeasure against turbine water induction, driplegs can be placed along main steam lines, hotand cold reheats and steam extraction lines.When a level switch senses the upper level in adrip leg it opens a dump valve to remove theaccumulated condensate.

Challenges: If particles of moisture escape condensate collection systems and enter theturbines, significant damage can result. Levelcontrols used in condensate drip legs must con-tend with the high temperatures and pressuresassociated with these devices.

INS

TR

UM

EN

TA

TIO

NDEAERATOR


ECLIPSE Model 706Guided Wave RadarTransmitter with a7YS Steam Probe

PLANT AREA:Steam Generation


ATLAS or AURORAMagnetic LevelIndicators can be sup-plied with switches ortransmitters

▲ Point Level:


CONDENSATE DRIP LEGS

▲ Point Level:

Model B40Float-ActuatedSwitch


▲ Point Level:


10

Application: Feedwater heaters use extractionsteam from the turbine to raise the temperature ofwater destined for the boiler. Water first passesthrough low-pressure heaters and into the deaer-ator where excess oxygen is removed. The feed-water then passes into the high-pressure heaterswhere it is further heated and pressurized. Twoseparate level control loops should manage eachfeedwater heater—according to ASME standards.

Challenges: Feedwater heater level is controlledto (1) prevent level from rising into the extractionline; (2) keep the tube surfaces in the condensingzone immersed; and (3) keep the drain coolerflooded. Level instrumentation must withstandmoderate to high temperatures and pressuresand turbulent conditions.

INS

TR

UM

EN

TA

TIO

N

Application: The steam drum is the primaryinterface between water and steam. In a coal-fired plant, boiler feedwater passes through theeconomizer and into the drum where the steamseparates from the feedwater and is drawn off tothe superheater. In combined-cycle operations, aHeat Recovery Steam Generator (HRSG) servesthe same purpose as a boiler. It is a gas-to-waterheat exchanger that extracts energy from the gasturbine exhaust gases and uses it to createsteam for the steam generator. HRSG Drums canbe high or low pressure varieties.

Challenges: Maintaining constant liquid level inthe upper part of the drum is necessary to pro-vide the proper quality of steam. Instrumentationmust withstand high temperatures and pressures.

INS

TR

UM

EN

TA

TIO

N

STEAM DRUMS PLANT AREA:Steam Generation

▲ Point Level:

Model B40Float-Actuatedor Series 3External CageSwitches


ECLIPSE Model 706Guided Wave RadarTransmitter with a7YS Steam Probe



Drums atop a HRSG

FEEDWATER HEATERS PLANT AREA:Steam Generation

▲ Point Level:

Model B40Float-Actuatedor Series 3External CageSwitches


E3 MODULEVEL orMODULEVEL PneumaticTransmitters; or ECLIPSEModel 706 GuidedWave Radar Transmitterwith 7YS Steam Probe



11

Application: The concentration of undesirablesolids in boiler water can be reduced throughthe use of a continuous purge or blowdownsystem. A blowdown tank receives continuousblowdown from the steam drum and blow-downs of variable temperatures and pressuresfrom the steam generator. A blowdown tankcan also function as a gravity feed drain for thesteam generator when the generator is drainedfor maintenance.

Challenges: Good boiler blowdown practicescan greatly reduce a boiler's water treatmentneeds and operation costs. Combustible mix-tures left in a boiler due to improper purges,however, have been known to cause cata-strophic explosions. Proper tank level controlsare essential to ensure a safe and effectiveboiler blowdown system.

INS

TR

UM

EN

TA

TIO

N

Application: A flash tank serves as a collectionsystem for a variety of condensate drain lines.Flash tanks receive high pressure condensatewhich is then exposed to a low pressure steamsource. When this occurs, a certain percentageof condensate will “flash” to steam at the lowerpressure. This steam can be “recycled” onother low pressure steam heat transfer devices.Smaller in size than traditional flash tanks, flashseparators utilize cyclonic action to instantlyseparate steam and condensate.

Challenges: Level measurement is necessaryto control flash tank level. The challenges areelevated temperatures and pressures.

INS

TR

UM

EN

TA

TIO

N

FLASH TANK

▲ Point Level:

Model B40Float-ActuatedSealed CageSwitch



ECLIPSE Model 706 Guided Wave RadarTransmitter with a7YS Steam Probe



BOILER BLOWDOWN TANK


ECLIPSE Model 706 Guided WaveRadar Transmitter with 7YSSteam Probe or E3 MODULEVELDisplacer-Actuated Transmitter


12

Application: Because modern high-pressureboilers evaporate several million pounds ofwater every working hour, the purity of feed-water circulating inside the boiler is essential.Chemical treatment reduces scale-formingmaterials and corrosive oxygen content. AFeedwater Evaporator can be used as an alter-native method to chemicals by removing impu-rities through evaporating raw water withextraction steam. Most often, the purity offeedwater is achieved by chemical treatment.

Challenges: Because support chemicals forwater treatment can include caustics, sodiumhypochloride, sulfuric acid or other additives,individual chemistry and storage requirementswill dictate the level instrumentation selected.

INS

TR

UM

EN

TA

TIO

N

Application: Service water is utilized for general plant services that include pump andinstrument seal water, fire water, demineraliza-tion, cooling and make-up water supply.Storage tanks with a capacity to support threedays to one week of operation, allow continuedplant operations in the event the supply ofwater is interrupted. Collectors and storagetanks are typically fixed roof, vertical cylindricalsteel tanks.

Challenges: Level measurement and flow detection devices are crucial for effectivewater source management. Typical measure-ment ranges are from 24 to 50 feet.

INS

TR

UM

EN

TA

TIO

NDEMINERALIZATION TANKS PLANT AREA:

Circulating Water

▲ Point Level:

Models T52or T62 Float-ActuatedSwitches


ECLIPSE Model 706Guided Wave RadarTransmitter


E3 MODULEVEL Displacer-ActuatedTransmitter

WATER SERVICES PLANT AREA:Circulating Water


ECLIPSE Model 706Guided Wave RadarTransmitter or PULSARModel R86 Pulse BurstRadar Transmitter

▲ Point Level:

Models B10or B15Displacer-ActuatedSwitches


ECHOTEL Models300 or 335Non-ContactUltrasonic Transmitters

13

Application: Power generating facilities havelarge, open atmosphere collection basinsknown as sumps that are usually found inwastewater treatment areas. Often constructedof concrete with depths ranging from four toten feet, sumps function as collection andtreatment sites for waste liquids ranging fromstorm water runoff to excess make-up water.With many possible uses for sumps, chemicalcomposition and temperatures will vary.

Challenges: Proper level control will helpensure the continuous operation of collectionand processing basins. Level controls in theseareas must often tolerate corrosive media,harsh chemicals, liquids with high solids con-tent and punishing weather conditions.

INS

TR

UM

EN

TA

TIO

N

Application: Open-system cooling towers rejectwaste heat from the steam cycle by exposing thecooling water directly to the atmosphere. Themajority of heat removed is due to evaporationand the remaining cooled water drops into a col-lection basin. Level control applications include ahigh level switch to avoid overflow conditions inthe cooling tower basin. In a once-through cool-ing system, the water intake structure is often avertical wet pit pump which requires high andlow level sensing and possible pump control.

Challenges: Water infeed and basin levels of thecooling tower require level sensing and control.In frigid climates, a level switch can work in tan-dem with a resistance heater to protect standingwater in the cooling tower basin against freezing.

INS

TR

UM

EN

TA

TIO

N

COOLING TOWER BASIN

▲ Point Level:

Models A15 orB10 Displacer-ActuatedSwitches

PLANT AREA:Circulating Water


ECLIPSE Model 706or Guided WaveRadar Transmitters


Kotron® Models82CE or 805RF CapacitanceTransmitters

OPEN ATMOSPHERE SUMPS PLANT AREA:Circulating Water

14

▲ Point Level:

Models A10 orB10 Displacer-ActuatedSwitches




ECLIPSE Model 706or Guided WaveRadar Transmitter

Lime slurry runoff

Application: Generators and gas turbines willhave integral lubricating systems to preventdamage caused by excessive friction. Often aportion of the lubricating oil is used in thehydraulic oil systems for hydraulic controldevices. Lubricating oil is typically stored inintegral stainless steel and carbon steel tanksthat are monitored for level. A generator gear-box lube oil system may have a reservoir with acapacity of 3,000 gallons and a turbine oil sys-tem may have a reservoir with a capacity of150 gallons.

Challenges: Adequate level monitoring of lubeoil reservoirs will ensure the proper functioningof turbines, electrical generators and otherequipment with integral lubrication systems.

INS

TR

UM

EN

TA

TIO

N

Application: The compressor of a gas turbineingests a large amount of air containing partic-ulate matter, aerosols of hydrocarbons andother organic compounds and gases. Althoughthe larger particulate matter is filtered out, theother compounds are deposited on the com-pressor blades. Compressor washing removesthis deposited fouling and restores the aerody-namic profile and compressor efficiency. Alsoused for cleaning generator or other machineryand equipment components, water wash isperiodically discharged as waste water.

Challenges: Water wash is collected in a dedi-cated collection tank monitored for level withtypical capacities of 50 to 100 gallons.

INS

TR

UM

EN

TA

TIO

NLUBRICATION OIL TANKS PLANT AREA:

Power Generation


ECLIPSE Model 706,Guided Wave RadarTransmitter, or PULSARModel R86 Pulse BurstRadar Transmitter

WATER WASH TANKS PLANT AREA: Power Generation

▲ Point Level:

Top MountFloat-ActuatedSwitches

▲ Point Level:

Tuffy® II Float-ActuatedSwitches


ECHOTEL Models 300or 335 Non-ContactUltrasonic Transmittersor ECLIPSE Model 706Guided Wave RadarTransmitter




Top Mount ATLASMagnetic LevelIndicator

15

AN INDUSTRY GUIDE TO LEVEL MEASUREMENT AND CONTROL FROM MAGNETROL

Other industry and special application brochures from MAGNETROL include:

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

• Crude Oil Processing

• Ethylene Applications

• Flue Gas Desulfurization

• Food & Beverage

• Interface Level Measurement

• Life Science

• Mass Flow Measurement

• Modular Skid Systems

• Natural Gas Processing

• Nuclear Power

• Petroleum Refining

• 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, Orion Instruments & Orion Instruments logotype, Echotel, Eclipse, Modulevel,Pulsar, Tuffy and Aurora are registered trademarks of Magnetrol International, Incorporated.

Copyright © 2018 Magnetrol International, Incorporated.

Bulletin: 41-175.4 • Effective: February 2018

Documents

INDUSTRY APPLICATIONS SERIES · 2019-01-04 · O ne hundred years ago, electric power was over 20 cents a kilowatt-hour— more than twenty times today’s cost. Back then electricity