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a sourcebook for industry

ImprovingSteam System

Performancea sourcebook for industry

Office of Industrial TechnologiesEnergy Efficiency and Renewable EnergyU.S. Department of Energy

One of aseries ofindustrialenergyefficiencysourcebooks

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AcknowledgementsTable of Contents

List of Figures and Tables

Quick Start Guide

Section 1: Steam System BasicsWhy Steam?

Steam System Operation

Generation

Distribution

End Use

Recovery

Section 2: Performance Improvement Opportunities

Overview

Systems Approach

Common Performance Improvement OpportunitiesBestPractices Steam System Improvement Tools

Overview of Financing Steam System Improvements

Section 3: Programs, Contacts, and Resources

OIT and BestPractices

Directory of Contacts

Resources and Tools

Appendices

Contents

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List of Figures

Figure 1. Steam System SchematicFigure 2. Firetube Boiler

Figure 3. Watertube Boiler

Figure 4. Thermostatic Steam Trap with a Bellows Element

Figure 5. Thermostatic Steam Trap with a Bimetallic Element

Figure 6. Inverted Bucket Steam Trap

Figure 7. Float and Thermostatic Steam Trap

Figure 8. Thermodynamic Disc Steam Trap

Figure 9. Shell and Tube Heat Exchanger

Figure 10. Components of a Plate and Frame Heat Exchanger

Figure 11. Configuration of a Jacketed Kettle Heat Exchanger

Figure 12. Thermocompressor Operation

Figure 13. Condensate Receiver Tank and Pump Combination

Figure 14. Flash Steam Recovery Vessel

List of Tables

Table 1. Key IOF Steam End-Use Equipment

Table 2. Common Performance Improvement Opportunitiesfor the Generation, Distribution, and Recovery Partsof Industrial Steam Systems

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This Sourcebook is designed to provide steam systemusers with a reference that describes the basicsteam system components, outlines opportunitiesfor energy and performance improvements, anddiscusses the benefits of a systems approach in

identifying and implementing these improvementopportunities. The Sourcebook is divided into threemain sections as outlined below.

This Sourcebook is not intended to be acomprehensive technical guide on improvingsteam systems, but rather a document that makesusers aware of potential performance improvements,provides some practical guidelines, and directsthe user to helpful resources. A systems approachanalyzes the supply and the demand sides of thesystem and how they interact, essentially shiftingthe focus from individual components to totalsystem performance. The cost-effective operationand maintenance of a steam system requireattention not only to the needs of individual piecesof equipment, but also to the system as a whole.

Often, operators are so focused on the immediatedemands of the equipment, they overlook thebroader question of how system parameters affectthe equipment.

Section 1: Steam System BasicsFor users unfamiliar with the basics of steamsystems, or for users seeking a refresher, a brief

discussion of the terms, relationships, and importantsystem design considerations is provided. Usersalready familiar with industrial steam systemoperation may want to skip this section. This sectiondescribes steam systems using four basic parts:generation, distribution, end use, and recovery.

overview of the finance considsteam system improvements. Asection discusses several resoudeveloped by the U. S. Depart(DOE) BestPractices Steam Pro

assess steam system improveme

Section 3: Programs, ContaThis section provides a directoand other organizations involvesystem marketplace. This sectiodescription of the BestPracticesdirectory of contacts, and a list

resources and tools, such as putraining courses, and videos.

AppendicesThe Sourcebook includes threeAppendix A is a glossary definisteam systems. Appendix B consteam system tip sheets. DeveloBestPractices Steam Program, tdiscuss common opportunities facilities can use to improve pereduce fuel use. Appendix C prfor submitting suggested changments to the Sourcebook.

Quick Start Guide

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Why Steam?

There are three principal forms of energy used inindustrial processes: electricity, direct-fired heat,and steam. Electricity is used in many differentways, including mechanical drive, heating, andelectrochemical reactions. Direct-fired energydirectly transfers the heat of fuel combustion to aprocess. Steam provides process heating, pressurecontrol, mechanical drive, component separation,and is a source of water for many process reactions.

Steam has many performance advantages that make

it an indispensable means of delivering energy.These advantages include low toxicity, ease oftransportability, high efficiency, high heat capacity,and low cost with respect to the other alternatives.Steam holds a significant amount of energy on aunit mass basis (between 1,000 and 1,250 Btu/lb)that can be extracted as mechanical work througha turbine or as heat for process use. Since most of

the heat content of steam is stored as latent heat,large quantities of heat can be transferred efficientlyat a constant temperature, which is a usefulattribute in many process heating applications.

Steam is also used in many direct contactapplications. For example, steam is used as asource of hydrogen in steam methane reforming,which is an important process for many chemical

and petroleum refining applications. Steam is alsoused to control the pressures and temperatures ofmany chemical processes. Other significantapplications of steam are to strip contaminants froma process fluid, to facilitate the fractionation ofhydrocarbon components, and to dry all types of

The many advantages that are asteam are reflected in the signifenergy that industry uses to genein 1994, industry used about 5,steam energy, which represents

of the total energy used in indufor product output1.

Steam use in the Industries of tespecially significant. For exampulp and paper industry used a2,197 trillion Btu of energy to gaccounting for about 83 percenused by this industry. The chemapproximately 1,855 trillion Btgenerate steam, which represenof the total energy used in this petroleum refining industry usedBtus of energy to generate steamabout 42 percent of this industry

Steam System O

This Sourcebook uses four catesteam system components and steam system performance: genend use, and recovery. These fopath of steam as it leaves the bthe condensate return system.

GenerationSteam is generated in a boiler osteam generator by transferringcombustion gases to water. Whenough heat, it changes phase fIn some boilers, a superheater f

Section 1: Steam System Basics

Ste

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DistributionThe distribution system carries steam from theboiler or generator to the points of end use. Manydistribution systems have several take-off lines thatoperate at different pressures. These distributionlines are separated by various types of isolationvalves, pressure regulating valves, and, sometimes,backpressure turbines. A properly performingdistribution system delivers sufficient quantities ofhigh quality steam at the right pressures andtemperatures to the end uses. Effective distributionsystem performance requires proper steam pressure

balance, good condensate drainage, adequateinsulation, and effective pressure regulation.

End Use

There are many different end uses of steam. Examplesof steams diverse uses include process heating,mechanical drive, moderation of chemical reactions,and fractionation of hydrocarbon components.

Common steam system end-use equipment includesheat exchangers, turbines, fractionating towers,strippers, and chemical reaction vessels.

In a heat exchanger, the steam transfers its latentheat to a process fluid. The steam is held in theheat exchanger by a steam trap until it condenses,

at which point the trap passes the cothe condensate return system. In a tusteam transforms its energy to mechadrive rotating machinery such as pump

or electric generators. In fractionatingfacilitates the separation of various coa process fluid. In stripping applicatiopulls contaminants out of a process falso used as a source of water for cerreactions. In steam methane reforminsource of hydrogen.

RecoveryThe condensate return system sends thback to the boiler. The condensate iscollection tank. Sometimes the makechemicals are added here while othedone in the deaerator. From the collecondensate is pumped to the deaeratooxygen and non-condensable gases. feed pumps increase the feedwater p

above boiler pressure and inject it into complete the cycle.

Figure 1 provides a general schematiof the four principal areas of a steamfollowing sections discuss the compoareas in greater detail.

Steam System Basics

CombustionGases

PressureReducing Valve

SteamTrap

Steam

SteamTrap

Economizer

Process Heater

Proce

Isolation Valve

Boiler

Combustion AirPreheater

Shell and TubeHeat Exchanger

Forced DraftFan

Distribution

End Use

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Generation

The generation part of a steam system uses a boiler

to add energy to a feedwater supply to generatesteam. The energy is released from the combustionof fossil fuels or from process waste heat. The boilerprovides a heat transfer surface (generally a set oftubes) between the combustion products and thewater. The most important parts of the generatingsystem include the boiler, the fuel supply,combustion air system, feedwater system, andexhaust gases venting system. These systems arerelated, since problems or changes in one generallyaffect the performance of the others.

Boilers

There are two basic types of boilers: firetube andwatertube. The fundamental difference betweenthese boiler types is which side of the boiler tubescontains the combustion gases or the boiler

water/steam.

Firetube Boilers. In firetube boigases pass inside boiler tubes, atransferred to water on the shell firetube boiler is shown in Figu

boilers are the most common tyfiretube boiler. The Scotch marindustry workhorse due to low advantages in efficiency and dumarine boilers are typically cylhorizontal tubes configured sucgases pass through these tubes,to boiler water on the shell side

Scotch marine boilers contain ramounts of water, which enablto load changes with relativelypressure. However, since the ba large water mass, it requires msteaming and more time to accin steam pressure. Also, Scotchgenerate steam on the shell sid

surface area, limiting the amou

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can generate. In general, Scotch marine boilers arenot used where pressures above 300 psig arerequired. Today, the biggest firetube boilers are over1,500 boiler horsepower (about 50,000 lbs/hr)5.

Firetube boilers are often characterized by theirnumber of passes, referring to the number of timesthe combustion (or flue) gases flow the length ofthe pressure vessel as they transfer heat to the water.Each pass sends the flue gases through the tubes inthe opposite direction. To make another pass, thegases turn 180 degrees and pass back through the

shell. The turnaround zones can be either drybackor water-back. In dryback designs, the turnaroundarea is refractory-lined. In water-back designs, thisturnaround zone is water-cooled, eliminating theneed for the refractory lining.

Watertube Boilers. In watertube boilerspasses through the tubes while the exremain in the shell side, passing oversurfaces. A representative watertube b

in Figure 3. Since tubes can typicallyhigher internal pressure than the largshell in a firetube, watertube boilers ahigh steam pressures (3,000 psi, somare required. Watertube boilers are ahigh efficiencies and can generate sasuperheated steam. In fact, the abilityboilers to generate superheated steam

boilers particularly attractive in applirequire dry, high-pressure, high-energincluding steam turbine power gener

The performance characteristics of wboilers make them highly favorable iindustries, including chemical manufand paper manufacturing, and refinin

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firetube boilers account for the majority of boilersales in terms of units, watertube boilers accountfor the majority of boiler capacity7.

Waste Heat Recovery Boiler (WHRB). These boilersmay be either firetube or watertube design and useheat that would otherwise be discarded to generatesteam. Typical sources of heat for WHRBs includeexhaust gases or high temperature products froman external manufacturing process in refineries andchemical manufacturing facilities or combustion ofa waste fuel in the boiler furnace.

Heat Recovery Steam Generators (HRSGs). HRSGstransfer energy from the exhaust of a gas turbine toan unfired or supplementary fired heat-recoverysteam generator to produce steam. Exhaust gasesleave the gas turbine at temperatures of 1000F(538C) or higher and can represent more than75 percent of the total fuel energy input. This energycan be recovered by passing the gases through a

heat exchanger (steam generator) to produce hotwater or steam for process needs. If the amount ofsteam needed by the process exceeds the amountproduced by simple heat recovery, thensupplementary fuel can be burned in the ductingbetween the gas turbine and the HRSG.

Superheaters. Superheaters add energy to steam,

resulting in a steam temperature that exceeds thesaturation temperature at a specific pressure.Superheaters can be convective or radiant.Radiative superheaters rely on the energytransferred directly from the combustion flame toincrease the energy level of the steam whileconvective superheaters rely on the transfer ofadditional energy from the flue gases to the steam.

Economizers. In many boilers, the flue gases stillhave useful amounts of energy even after theyhave passed through the boiler. In many of theseapplications, economizers provide effectivemethods of increasing boiler efficiency bytransferring the heat of the flue gases to incoming

designed to handle flue gas concondensing economizers must btemperatures that are reasonablypoints of the flue gas compone

of the flue gases depends largewater in the gas, which, in turnamount of hydrogen in the fuelavoid condensation in the exhaby burning natural gas, the exhshould typically be kept above economizers are designed to alof the exhaust gas components.

recovery, these economizers tyenergy than do non-condensingOften, special materials are req

For more information on econoSteam Tip Sheet Number 3 titleEconomizers for Waste Heat Rec

Combustion Air Preheaters. Com

preheaters are similar to econotransfer energy from the flue gasystem. In these devices, howetransferred to the incoming comefficiency benefit is roughly 1 p40F increase in the combustio

Boiler Insulation

The walls and combustion regitypically lined with insulating menergy loss and to prevent leakseveral types of boiler insulatingbrick, refractory, insulation andselection and design of boiler idepend largely on the age and Since the insulating lining is ex

temperatures and is subject to dbe periodically inspected and rnecessary.

Boiler Control SystemBoiler control systems are desigb il d t b i

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Combustion Control System. The combustion controlsystem regulates the fuel air mixture to achievesafe and efficient combustion and maintains steamsystem pressure. Control systems have varying

levels of sophistication. Simple systems use a fixedlinkage between the fuel-regulating valve and thecombustion air damper. This is called single pointpositioning. A change in steam pressure makes aproportional change in the combustion air andfuel. Advanced systems rely on signals fromtransmitters to determine independent fuel valveand air damper positions. This is called a full mon-

itoring system.

For more information see the Steam Tip SheetNumber 4 titled Improve Your Boilers CombustionEfficiencyin Appendix B.

Burner Flame Safeguard System. A flame safeguardsystem is an arrangement of flame detectionsystems, interlocks, and relays which will sense

the presence of a proper flame in a furnace andcause fuel to be shut off if a hazardous conditiondevelops. Modern combustion systems are closelyinterlocked with flame safeguard systems and alsopressure-limit switches, low-water level cutoffs,and other safety controls that will stop the energyinput to a boiler when an unsafe condition develops.The flame safeguard system senses the presence of a

good flame or proper combustion and programs theoperation of a burner system so that motors, blowers,ignition, and fuel valves are energized only whenthey are needed and then in proper sequence.

Safety Shutoff Valve. Safety shutoff valves isolatethe fuel supply to the boiler in response to certainconditions such as low or high gas pressure orsatisfied load demand. The type of safety shutoffvalves and the settings are often determined bycode or insurance requirements.

Water Level Control. The boiler water level controlsystem ensures a safe water level in the boiler.Typically, the control system provides a signal to

Safety Valve. The safety valve is the mvalve on the boiler and keeps the boexceeding its maximum allowable wpressure (MAWP).

Steam Pressure Control. Steam pressuregulate the combustion equipment tconstant pressure in the steam headepressure rises above or falls below thsetting, the control adjusts the burnerbring the pressure back to the setpoin

Nonreturn Valve. The nonreturn valvecombination shutoff and check valvesteam out of the boiler, but prevents the steam header in the event the bodrops below that of the header. The vaonly when the pressure inside the boslightly above the steam header press

Steam Flow Meter. Steam flow meters

in evaluating the performance of the can provide useful data in assessing bperformance, calculating boiler efficitracking the amount of steam required In some systems, steam flow meters pmeasurement signal for the boiler coAdditionally, steam flow meters can bbenchmarking efforts.

There are three basic types of steam fdifferential pressure (DP), vortex, andDifferential pressure flowmeters rely in pressure as steam flows by an elemnozzle, orifice, or venturi. This pressprovides an indication of flow velociin turn, can be used to determine theVortex flowmeters rely on the princippast an element creates vortices that hathat correspond to the flow velocity. flowmeters rely on tubes placed in thpath that twist according to the veloci

Boiler Feedwater System

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Feedwater Flow Control Valve. A modulatingfeedwater flow control valve moves up or downin response to the water level transmitter(s). Onsmaller firetube boilers, it is not uncommon for the

feedwater valve to operate in a closed or openposition, depending on the water level transmittersignal.

Softener. Softeners remove hardness minerals, suchas calcium, magnesium, and iron, from a watersupply. The presence of hardness in boiler waterleads to many problems, including scale buildup

and foaming, which reduce boiler efficiency andcan cause tube failure. Softeners reduce this prob-lem through an ion exchange process. As the hardwater passes through a chamber filled with resin,an exchange occurs that removes hardness miner-als from the water. The sodium that replaces thehardness minerals has a higher solubility in waterand generally will not form scale.

Pretreatment Equipment. Pretreatment equipmentimproves the quality of the incoming water so thatit may be used in the boiler without excessivescaling or foaming, which can reduce boilerefficiency and cause tube failure. Pretreatmentequipment includes, but is not limited to, clarifiers,filters, softeners, dealkalizers, decarbonators, reverseosmosis (RO) units, and demineralizers.

Deaerator, Deaerating Heater, and AtmosphericDeaerator. The presence of oxygen in the boilersystem can be a significant problem due to itscorrosivity at high temperatures. Deaerators anddeaerating heaters use heat, typically steam, toreduce the oxygen content in water. Deaeratorsand deaerating heaters are typically pressurizedtanks that raise the water temperature to the pointof saturation. They also break the incoming waterinto either fine droplets or thin sheets to facilitatethe removal of oxygen and other noncondensiblegases. Depending on the design, the feedwateroxygen content can be reduced to levels rangingfrom 7 to 40 parts per billion (ppb).

removal as deaerators and deaetypically providing water with o0.5 to 1 parts per million (ppm

In applications that require loweachievable with a deaerator, deopen feedwater heater, a cheman oxygen scavenger, can be uoxygen. In most systems, an oxpart of the systems water treatm

For more information on these d

Tip Sheet Number 18 titled DeSteam Systems, provided in Ap

Feedwater Pump. Feedwater pufrom the deaerator to the boileare driven by electric motors oIn a modulating feedwater systepumps run constantly as opposoperation in relatively small bo

Collecting/Storage Tank. The retoften erratic due to changing stby the end uses. The condensatto a condensate receiver or direif the system does not have a rewater may also be stored in a tThis provides the boiler system

water capacity in case the pretmalfunctions. The condensate aor makeup, are transferred fromto the deaerator prior to being

Boiler Combustion Air SysThe combustion air system supnecessary for the combustion re

enough air for the amount of fuboilers, fans are typically requivalves, or variable speed drivesthe amount of air allowed into

Forced Draft Fan. A forced draftinlet of a boiler and pushes am

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Induced Draft Fan. Induced draft fans are locatedon the outlet gas side of the boiler and pull fluegases out. The induced draft fan creates a slightlynegative furnace pressure that is controlled by

outlet dampers on the boiler. In some systems wherea bag house, mechanical collector, or precipitatoris involved, special considerations should be givenin sizing and selection of this fan.

Damper. Dampers control the amount of airallowed into and out of a combustion chamber.Dampers, in combination with fuel regulating

devices, are positioned by the combustion controlsystem to achieve certain fuel:air ratios. Damperson the boiler outlet are used to regulate thenegative furnace draft.

Boiler Fuel SystemThere are many different types of fuels used inboilers, requiring several different types of fuelhandling systems. Fossil fuels such as coal, oil, andgas are most commonly used. Waste fuels are usedin many industries, particularly the forest products,petroleum refining, and chemical manufacturingindustries where there is an available supply ofwaste products such as bark, wood chips, blackliquor, and refinery gas.

Fuel Regulating Valve. In gaseous and liquid fuels,

regulating valves control the fuel delivered to theboiler. In many systems these valves can be quicklyshut in response to an operating problem.

Fuel. The fuel types that are commonly used inboilers include natural gas, coal, propane, fueloils, and waste fuels (for example, black liquor,bark, and refinery gas). Fuel type significantly

affects boiler operation, including efficiency,emissions, and operating cost. Natural gas accountsfor about 36 percent of the total U.S. industry boilercapacity. Coal accounts for about 14 percent ofthe boiler capacity. Fuel oils account for about21 percent. Other fuels, which include waste fuels,account for about 29 percent of the boiler capacity9

fuel, it is important to know the enerthe fuel when determining boiler effi

For more information see the Steam T

Number 15 titled Benchmark the FueSteam Generationin Appendix B.

Burner. Burners combine the fuel and combustion. There are many differenburners due to the many different typAdditionally, burners have different pcharacteristics and control requireme

burners are on/off while others allowsetting of the fuel:air mixture over a rconditions. Some burners can fire diffuel, allowing boiler operation to conthe loss of one fuel supply.

Boiler Blowdown SystemThe boiler blowdown system includeand the controls for the continuous bbottom blowdown services. Continuoremoves a specific amount of boiler wmeasured in terms of percentage of fein order to maintain a desired level odissolved solids in the boiler. Setting the continuous blowdown is typicallyconjunction with the water treatmentSome continuous blowdown systems

input of sensors that detect the level solids in the boiler water.

The bottom blowdown is performed particulates and sludge from the bottboiler. Bottom blowdowns are periodtypically performed a certain numbeshift or according to a set schedule. I

systems, bottom blowdowns are contautomatic timer. Bottom blowdown sbe permitted unless it is recommendeboiler manufacturer. This is because pressure boilers, especially those abobottom blowdown may cause water ssome portions of the boiler circuit

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and flash tank. Flash tanks permit the recovery oflow-pressure flash steam, which can be used indeaeration or process heating. They also permit theuse of a smaller heat exchanger than would be

required without the flash tank. Blowdown heatexchangers are most often used to preheat boilermakeup water.

For more information on boiler blowdowns, see theSteam Tip Sheets Numbers 9 and 10 titled MinimizeBoiler Blowdown, and Recover Heat from BoilerBlowdownin Appendix B.

Distribution

The distribution system transports steam from theboiler to the various end uses. Although distributionsystems may appear to be passive, in reality, thesesystems regulate the delivery of steam and respondto changing temperature and pressure requirements.

Consequently, proper performance of the distributionsystem requires careful design practices and effectivemaintenance. The piping should be properly sized,supported, insulated, and configured with adequateflexibility. Pressure regulating devices such aspressure reducing valves and backpressure turbinesshould be configured to provide proper steambalance among the different steam headers.Additionally, the distribution system should beconfigured to allow adequate condensate drainage,which requires adequate drip leg capacity andproper steam trap selection. Steam distributionsystems can be broken down into three differentcategories: buried pipe, above-ground, and buildingsections, and selection of distribution components(piping, insulation, etc.) can vary depending on thecategory.

PipingSteam piping transports steam from the boiler tothe end-use services. Important characteristics ofwell-designed steam system piping are that it isadequately sized, configured, and supported.

Important configuration issues drainage. With respect to flexibespecially at equipment connecaccommodate thermal reaction

startups and shutdowns. Additishould be equipped with a suffappropriately sized drip legs tocondensate drainage. Additionalbe pitched properly to promotecondensate to these drip lines. drainage points experience twooperating conditions: normal o

up; both load conditions shoulthe initial design.

InsulationThermal insulation provides imenergy savings, and performancof safety, insulation reduces thetemperature of the steam pipinrisk of burns. A well-insulated heat loss to ambient workspacethe work environment more coConsequently, the energy savinreduced energy losses from thereduced burden on the cooling heat from workspaces. In additenergy benefits, insulation incrsteam energy available for end

the amount of heat lost from the

Important insulation propertiesconductivity, strength, abrasionworkability, and resistance to wThermal conductivity is the meper unit thickness. Thermal coninsulation varies with temperat

is important to know the right twhen selecting insulation. Strenof the insulations ability to maunder mechanical loads. Abrasability to withstand shearing foa measure of the ease with whiinstalled Water absorption refe

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Some common insulating materials used in steamsystems include calcium silicate, mineral fiber,fiberglass, perlite, and cellular glass. The AmericanSociety for Testing and Materials (ASTM) provides

standards for the required properties of these andother insulation materials.

Additionally, the North American InsulationManufacturers Association (NAIMA) has developeda software program titled 3E Plus that allows usersto determine the energy losses associated withvarious types and thicknesses of insulation. The

3E Plus program facilitates the assessment of variousinsulation systems to determine the most cost-effectivesolution for a given installation. See Section 2, page 27for more about 3E Plus Insulation software, whichcan help steam users assess insulation opportunities.

For more information on insulation, refer to Steam TipSheets Numbers 2 and 17 titled Insulate SteamDistribution and Condensate Return Lines and

Install Removable Insulation on Uninsulated Valvesand Fittings. Both can be found in Appendix B.

ValvesIn steam systems, the principal functions of valves areto isolate equipment or system branches, to regulatesteam flow, and to prevent overpressurization. Theprincipal types of valves used in steam systems

include gate, globe, swing check, pressure reducing,and pressure relief valves. Gate, globe, and swingcheck valves typically isolate steam from a systembranch or a component. Pressure reducing valves(PRV) typically maintain certain downstream steampressure conditions by controlling the amount ofsteam that is passed. These reducing valves areoften controlled by transmitters that monitor down-stream conditions. Pressure relief valves releasesteam to prevent overpressurization of a systemheader or equipment.

Steam SeparatorsIn some steam systems, wet steam is generated. This

t t t i t d l t th t d

exchange components as well as resuhammer. Removing water droplets bereach end-use equipment is necessar

Steam separators remove water droplrelying on controlled centrifugal flowforces the entrained moisture to the ouit is removed from the separator. The mture removal could be a steam trap ormanufacturers include the trap as an of the unit. Additional accessories incgage connections, thermometer conn

vent connections.

Steam separators can be installed in ehorizontal or vertical line. They are cremoving 99% of particulate entrainmand larger over a wide range of flowsare often designed in accordance withSection VIII, Division 1 with pressure

Steam AccumulatorsA steam accumulator is a large insulavessel, partially filled with hot water (saWhen steam supply exceeds demandhigh-pressure steam is charged into ththrough special charging nozzles. Thcondensed, giving up its latent heat, pressure, temperature, and heat conte

body. When the steam demand exceethe pressure in the accumulator dropadditional required steam flashes fromtaking back the heat previously storesystem of control valves and check vathe charging and discharging. The excharged quietly and smoothly, and wneeded, it is available with the speedvalve operation. There is also an accuthat stores hot water for use as boiler

Steam TrapsSteam traps are essential for proper dsystem performance. During system sll i d l titi f d

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Thermostatic Traps

Thermostatic traps use temperature differential todistinguish between condensate and live steam.This differential is used to open or close a valve.

Under normal operating conditions, the conden-sate must cool below the steam temperature beforethe valve will open. Common types of thermostatictraps include bellows and bimetallic traps.

Bellows Traps. Bellows traps include a valveelement that expands and contracts in response totemperature changes. Often a volatile chemical

such as alcohol or water is inside the element.Evaporation provides the necessary force to changethe position of the valve. At start up, the bellowstrap is open due to the relative cold condition. Thisoperating condition allows air to escape andprovides maximum condensate removal when theload is the highest. Bellows traps can fail eitheropen or closed. The configuration of a bellowssteam trap is shown in Figure 4.

Bimetallic Traps. Bimetallic traps rely on the bend-ing of a composite strip of two dissimilar metals toopen and close a valve. Air and condensate passfreely through the valve until the temperature of the

bimetallic strip approaches the steam temperature.After steam or relatively hot condensate heats thebimetallic strip and causes it to close the valve,the trap remains shut until the temperature of thecondensate cools sufficiently to allow the bimetallicstrip to return to its original shape and therebyopen the valve Bimetallic traps can fail in either

movement causes a valve to opare a number of mechanical trabased on this principle. They infloat and lever, inverted bucketfloat and thermostatic traps.

Ball Float Traps. Ball float trapsment of a spherical ball to ope

outlet opening in the trap bodycondensate is present, the ball opening, thereby keeping air anescaping. As condensate accumtrap, the ball floats and uncoveopening. This movement allowflow continuously from the trapequipped with a separate air vecannot vent air on start up.

Float and Lever Traps. Float ansimilar in operation to ball floaball is connected to a lever. Wupward due to accumulation othe trap body, the attached levea valve to open. This action allcontinuously flow from the trap

load decreases and steam reachward ball movement causes thethereby keeping steam from escare equipped with a separate alever traps cannot vent air on sdiscussion on float and thermo

Steam System B

Figure 4. Thermostatic Steam Trap with a BellowsElement

Steam &Condensate

In

LiquidCondensate& Flash Out

Bellows Element

Valve

Seat

Steam and/orHot condensateDepending on

Trap

Steam orCondensate

In

Hot orSubcooled Liquid

Condensate

Figure 5. Thermostatic Steam TrElement

Valve Se

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Steam System Basics: Distribution

As steam enters the trap and is captured inside thebucket, it causes the bucket to move upward.This upward movement closes the valve and keepssteam from escaping. When the condensate

collects and cools the steam, the bucket movesdownward. This movement causes the valve toopen thereby allowing the condensate to escape.Unlike closed float traps, inverted bucket trapshave intermittent discharge. These traps can bedepleted of their condensate seal when appliedin superheated steam service. If this occurs, the trapwill continuously discharge live steam. This traptype is not recommended for superheated steamservice, unless special installation conditions aremet. The configuration of an inverted bucket steamtrap is shown in Figure 6.

Open Bucket Traps. Open bucket traps consist of anupright bucket that is attached to a valve. At start up,the bucket rests on the bottom of the trap body. Inthis position, the valve is wide open. As condensateaccumulates in the trap body on the outside of thebucket, the bucket floats upward causing the valveto close. When sufficient condensate accumulatesoutside the bucket, it spills over the top and fills theinside of the bucket. At this time, the bucket sinks

causing the valve to open. This trap is also prone tofailure when applied in superheated steam servicebecause of the loss of the condensate seal. Likeinverted bucket traps, open bucket traps haveintermittent discharge.

Thermodynamic Traps

Thermodynamic traps use the differeenergy (velocity) between condensatesteam to operate a valve. The disc tracommon type of thermodynamic trapor impulse traps are sometimes used.

Disc Traps. Disc traps use the positioto control steam and condensate flowcondensate flows through the trap, thethereby causing the trap to open. As pass through the trap the disc moves The force that causes the disc to movis generated by the difference in presthe low-velocity steam above the dishigh-velocity steam that flows throug

gap beneath the disc. Disc traps coman intermittent discharge and, when normally fail open. The configurationsteam trap is shown in Figure 8. Gen

Figure 6. Inverted Bucket Steam Trap

Inverted Bucket

Seat Steam SpacesCondensate Level

Steam BubblesVent Hole

Valve

Lever

LiquidCondensate& Flash Out

Figure 7. Float and Thermostatic Steam

SeatFloat Lever

SteamSpace

Steam &Condensate In

CondensateLevel

Li&

Figure 8. Thermodynamic Disc Steam

Steam &Condensate

In

V

Outlet Port

Seating Surface Inlet Port

B

FlaVa

Steam &Condensate

In

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disc traps, piston traps are phase detectors thatsense the difference between a liquid and gas orvapor. They continuously discharge any air andcondensate. Their primary failure mode is open.

Lever Traps. Lever traps are a variation of thethermodynamic piston trap. They operate on thesame principal as a piston trap but with a leveraction to pass large amounts of condensate and airon a continuous basis. Their primary failure modeis open.

Orifice Traps. Orifice traps are of two basic types:orifice plate and short tube. Both trap typesoperate under the exact same principles. A simpleorifice plate steam trap consists of a thin metalplate with a small-diameter hole (orifice) drilledthrough the plate. When installed, condensate thataccumulates is continuously removed as the steampressure forces the condensate through the orifice.During conditions when no condensate is present,

a limited amount of steam flows through the orifice.The report Review of Orifice Plate Steam Traps inResources: Reports and Technical Papers on page51 of the Programs, Contacts, and ResourcesSection, provides information for making informeddecisions about when orifice plate steam trapsshould be considered for use in new or existingsteam systems.

Additional information regarding steam traps isavailable in the Steam Tip Sheet Number 1 titledInspect and Repair Steam Traps, found inAppendix B.

Steam MetersThe use of flowmeters within the distribution sys-

tem can provide important data for monitoring theefficiency of a process or an end use. Tracking theamount of steam required can be particularlyuseful in benchmarking efforts. The types of steamflowmeters are discussed in the Generation Section.

End Use

end-use equipment includes heto transfer thermal energy and tmechanical energy. In manufacsteam end uses often directly su

making their performance and to plant productivity. Improvemefficiency and effectiveness alsbetter performance and increasis a wide range of end-use equto the advantages of steam thatthe Introduction. Some of the mcomponents are discussed in th

For the purposes of this discussequipment is grouped into thre

Industries of the Future11 (IOequipment;

Conditioning and control eq

Additional equipment.

The key IOF equipment categolargest uses of steam in those inIOF facilities use steam for othethe key end uses account for thsteam use. The conditioning eqincludes equipment that facilitaof steam. The additional equipincludes equipment that is used

and, though significant, does nof the steam use in IOF industr

Industries of the Future Ke

EquipmentIn the three IOF industries of fopetroleum refining, and chemicfor the largest amount of end-us

IOF industry, steel production, significant amount of end-use eto generate most of that industrpower. Table 1 provides a list ofend-use equipment for IOF ind

C d

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They remove energy from the exhaust steam allowingit to be recovered as condensate. In steam ejectorapplications, condensers increase the effectiveness

of the ejectors by condensing both the motivesteam and condensables pulled from the process,reducing the amount of motive steam required.

Condensers can be surface type or barometric.Surface condensers are supplied with cooling water

applications, condensers are also usecomponents from gaseous mixtures. applications, the condensers use a co

to extract energy from the gases and condensed components.

Distillation Towers

The petroleum refining and chemical industries use large amounts of steam

Steam System Basics: End Use

Equipment Process Application IndustryCondenser Steam turbine operation Aluminum, Chemical Manufacturin

Products, Glass, Metal Casting, PeRefining, and Steel

Distillation tower Distillation, fractionation Chemical Manufacturing, Petroleu

Dryer Drying Forest Products

Evaporator Evaporation/concentration Chemical Manufacturing, Forest PPetroleum Refining

Process heat Alkylation, Process air heating, Process water Aluminum, Chemical Manufacturinexchanger heating, Gas recovery/Light ends distil lation, Products, Glass, Metal Casting, Pe

Isomerization, Storage tank heating Refining, and SteelVisbreaking/Coking

Reboiler Fractionation Petroleum Refining

Reformer Hydrogen generation Chemical Manufacturing, Petroleu

Separator Component separation Chemical Manufacturing, Forest PPetroleum Refining

Steam ejector Condenser operation, Vacuum distil lation Aluminum, Chemical ManufacturinProducts, Glass, Metal Casting, PeRefining, and Steel

Steam injector Agitation/blending, Heating Chemical Manufacturing, Forest PPetroleum Refining

Steam turbine Power generation, Compressor mechanical Aluminum, Chemical Manufacturindrive, Hydrocracking, Naphtha reforming, Products, Glass, Metal Casting, PePump mechanical drive, Feed pump Refining, and Steelmechanical drive

Stripper Distillation (crude and vacuum units), Chemical Manufacturing, PetroleuCatalytic cracking, Asphalt processing,

Catalytic reforming, Component removal,Component separation, Fractionation,Hydrogen treatment, Lube oil processing

Thermocompressor Drying, Steam pressure amplification Forest Products

Table 1. Key IOF Steam End-Use Equipment

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into the bottom of these towers to reduce thepartial pressures of the hydrocarbons, whichfacilitates their separation, and to reduce cokeformation on tray and tower surfaces.

Dryers

Dryers reduce the water content of a solid. Dryersaccount for the largest end use of steam in the pulpand paper industry12. The chemical manufacturing,textiles, and food processing industries also uselarge amounts of steam for drying. Dryers can beindirect or direct. Indirect dryers remove moisture

thermally as energy is transferred from condensingsteam, flue gases, or high temperature processfluid to the product being dried. Common indirectdryer types are coil and rotating drum. Direct dryersuse hot gases that have been heated with steam orflue gases to directly contact and dry a product.

Dryers, like evaporators, can be arranged in multiple-stage configurations. Multiple-stage steam dryersuse a cascading set of steam pressures, allowingsteam released from an upstream stage to supplysteam to the next stage. In many multiple-stagedryers, thermocompressors are used to increase thesteam pressure of downstream-effect stages.

Evaporators

Evaporators reduce the water content of a liquid,

generally by heating it with steam in order toconcentrate the product. Evaporators are usedextensively in industries such as food processing,chemical manufacturing, steel, forest products, andtextiles.

In most cases, evaporators are shell and tube heatexchangers with the steam on the shell side and

the product being concentrated in the tubes.Evaporators can be single effect or multiple effect.A single effect evaporator uses steam at one set ofpressure and temperature conditions to boil off thevapor from a product. Multiple-effect evaporatorstake the vapor produced from one evaporator and use

h h d l

Heat Exchangers

Heat exchangers transfer thermfluid to another. In manufacturis a common source of heat for

of which are discussed in the Ina wide range of heat exchangesteam, largely due to the wide raare heated with steam. Many pconsiderations must be incorporaof a heat exchanger. Some basitypes are discussed below, incl

Tubular; Plate and frame;

Jacketed; and

Coil.

Tubular Heat Exchanger. Tubularare tube bundles that are surrouor heating medium. This type oincludes finned tube and shell shown in Figure 9. Finned tube often used to heat air for dryingapplications. Shell and tube heoften used for liquid heating anSince the tube side of shell and can be designed to withstand hsometimes exceeding 1,500 psof this type are often used in hi

high-pressure applications.

Plate and Frame Heat Exchangerheat exchangers, the two heat eseparated by plates. The plates ridged, as shown in Figure 10, surface area available for heat frame heat exchangers are ofte

viscosity applications, where thless severe. The plate ends are gasketed covers that can be remdisassembly and cleaning. Thistype is used when temperaturemoderately low, typically belowPl t d f h t h

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Jacketed Heat Exchangers.Jacketed heat exchangersuse an enclosure to surround the vessel thatcontains the heated product. A common exampleof a jacketed heat exchanger is the jacketed kettle.A representation of a jacketed heat exchanger isshown in Figure 11. Jacketed heat exchangers are

practical for batch processes and for product typesthat tend to foul or clog tube bundles or coils.

Coil Heat Exchangers. Coil heat exchangerscharacteristically use a set of coils immersed in themedium that is being heated. Coil heat exchangersare generally compact, offering a large heat transferarea for the size of the heat exchanger.

Reboilers

Reboilers are typically used in distilling processesto increase component separation. Reboilers useheat, often provided by steam, to evaporate thevolatile components of a product that has been

drawn from a fracttower. These volatnents are sent dowfurther processing.

components are sethe fractionating toon to a vacuum diprocess. There areof reboilers, includkettle, kettle, internand thermosyphonThese designs diffeanother in the wayis heated with stea

Reformers

Steam reformers are used to generatetypically from a hydrocarbon feedstomethane (the largest component of nturn, hydrogen is used in many petroand chemical manufacturing process

use steam for both energy and as a sohydrogen. Steam is injected with the feedstock to initiate the following rea

Reformers often have secondary stagused to convert the carbon monoxidedioxide and additional hydrogen. Altamounts of steam are used throughoureforming processes, steam is also genreformers and is sometimes exported f

Steam System Basics: End Use

Figure 9. Shell and Tube Heat Exchanger

Tube Side Fluid

Tube BundleTubesheet

Shell Side Fluid

Baffles

PlatesFrame

Kettle

Steam

CH4 + H2O CO +

Methane Steam Carbonmonoxide

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Steam Ejectors

Steam ejectors use steam flow through a nozzle tocreate a vacuum (similar in operation to thermo-compressors). They are used in several different

types of system applications and process equipment.Low-pressure conditions promote the evaporationof liquids at reduced temperatures. Consequently,many chemical manufacturing processes use steamejectors to increase the concentration of a product.In petroleum refining, steam ejectors are commonlyused in the vacuum distillation of heavy hydrocarbonproducts. Steam ejectors are also used to initiate

and maintain vacuum conditions in the condensersof condensing turbines.

Steam Injectors

Steam injectors are used to inject steam directlyinto a tank or a pipe containing a process fluid,generally for heating purposes. Many injector typesuse a nozzle and a diffuser to pull process fluid into

the steam before the mixture is injected into theprocess fluid to promote an even distribution of heat.Important performance characteristics of injectorsinclude accurate control of the amount of steaminjected and effective mixing of the steam and process.

Steam Turbines

Steam turbines are used to drive electric generatorsor other rotating machinery such as compressors,pumps, and fans. Steam turbines are used in manydifferent system designs, depending on the relativerequirements for steam, electricity, or othermechanical loads. Steam turbines provide aneffective means of stepping down steam pressurewhile extracting mechanical work.

Additional information regarding steam turbines is

available in Steam Tip Sheets Numbers 15 and 21titled Benchmark the Fuel Costs of Steam Generationand Consider Steam Turbine Drives for RotatingEquipment, found in Appendix B.

Some turbines have interstage take-offs that allow

amount of extracted steam canelectric power to be generatedrespectively less or more steamplant.

Backpressure Turbines. Backpreexhaust steam at pressures thatatmospheric, and the exhaust sfor other services. By extractingfrom steam, backpressure turbiefficient means of supplying lofrom a high-pressure header.

Condensing Turbines. Condensinsteam to vacuum (sub-atmosphThis steam is condensed in a hreferred to as a condenser, andcondensate return system. Contypically require a source of cocondense the steam.

StrippersSteam strippers are used to remfrom a solution. Strippers are cpetroleum refining and chemicapplications, where process socomponents that have differentremoval of one or more of the necessary. Injecting steam into

lowers the partial pressure of vallowing some of them to vapotransported away with the stearaise the temperature of the misolubility of the objectionable mit to strip off with the steam. Othe contaminants are condenseallowing recovery of the condenor further processing of the con

Thermocompressors

Thermocompressors combine hlow-pressure steam to form an pressure steam supply. (See Figu

y

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Conditioning and Control EquipmentConditioning equipment is generally used toimprove the performance of, or to protect the end-use equipment. For example, desuperheaters areoften used to control the energy of a steam supply

to end-use equipment to reduce the risk of damageto the equipment or to effectively improvetemperature control of the process.

Desuperheaters

The purpose of a desuperheater is to remove thesuperheat from steam. The majority of heating andprocess equipment performs more efficiently using

saturated rather than superheated steam. Desuper-heaters inject a very fine mist of high-purity water,such as condensate, into the steam flow. Thesuperheated vapor gives up heat to the water mist,and by doing so, reduces its temperature.

Vacuum Breakers

Vacuum conditions can develop in a steam system

when steam flow into a component or a branch isthrottled or shut off. If the rate of downstreamsteam use exceeds the steam supply, the pressuredecreases and vacuum conditions can form.Vacuum conditions also result when the load onthe heat exchanger is significantly less than theh t h it If th i th h t

increasing the risk by condensate. Vacare pressure-controthat essentially ven

exchanger or systewhich a vacuum hallowing in air whvacuum breakers rand allow the condedrain.

Air Vents

Before startup, the contains air that mremoved. The pres

a steam system reduces heat transfer and promotes condensate corrosion. remove this air. Air vents are often thdevices, similar to thermostatic steamon the temperature difference betweesteam. When exposed to the lower te

in the system side, the vent opens. Astemperature steam reaches the vent, preventing the escape of steam.

Traps

Steam traps are important to the perfoend-use equipment. Traps provide foremoval with little or no steam loss. If th

function properly, excess steam will floend-use device or the condensate will Excess steam loss will lead to costly opcondensate backup will promote poorand may lead to water hammer. Trapremove noncondensible gases that reexchanger effectiveness. There are setypes of steam traps, which are discu

Distribution section of this Sourceboo

Insulation

End-use equipment, such as heat excturbines, should generally be insulatesignificant heat loss that the surface a

y

Figure 12. Thermocompressor Operation

Discharge(intermediate

pressure)

Motive Steam(high pressure)

Suction (low pressure)

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Additional EquipmentThe additional equipment category refers to end usesthroughout industry, which, though still significantusers of steam, generally account for less steam

energy than the key IOF end uses.

Absorption Chillers

Absorption chillers provide cooling using aninteresting variation of the vapor compression cycle.Instead of a compressor, which is generally used inchillers, absorption chillers exploit the ability ofone substance to absorb a refrigerant at one

temperature and then release it at another. Inammonia-based systems, water is the absorbentand ammonia is the refrigerant. In lithium bromide-based systems, lithium bromide is the absorbent,while water is the refrigerant.

An absorption chiller uses a pump instead of acompressor to increase refrigerant pressure. Once itis at the higher pressure, the absorbent/refrigerantsolution is heated, often with steam, whichreleases the refrigerant. Although absorption chillersgenerally have lower coefficients of performance(COP) (indicating lower thermodynamic efficiency)than traditional chillers, they use less electricpower per ton of cooling and are well suited foruse with steam systems.

HumidifiersHumidifiers inject steam into an air or other gassource to increase its water vapor content. Inhumidification, steam is used as a source of bothwater and energy. Humidification applications arefound in the chemical manufacturing industrywhere control of ambient temperature and moisturecontent are critical for product quality.

Preheat/Reheat Air Handling Coils

Steam is often used in space heating applicationsto preheat and reheat air. In many HVAC systems,the conditioned air must have both its temperatureand humidity adjusted. In preheat applications,

workspaces, steam coils must rair stream up to the proper temreheat and preheat applicationexchangers are generally used.

Tracing

In tracing applications, steam ithe temperature of a fluid in a application of tracing lines is to of a process fluid in piping thattemperature controlled area. Siexposed to freezing conditions

steam flow, and condensate drato prevent freezing of the tracinthe process piping.

Meters

Steam meters are used to measand are important for tracking tparticular part of a steam systemend use. Discussion of differenprovided in the Steam GeneratSourcebook.

Recover

The recovery components of a sand return condensate back to

of the system. Condensate recothermal and water treatment bethat is not returned must be comthe addition of makeup water, wmuch cooler than condensate. temperature often exceeds 200water temperature is typically b80F. As a result, the enthalpy dcondensate and makeup water

120 Btu/lb, an amount of energthan 10 percent of the energy igenerated steam.

Additionally, makeup water is gchemicals that remove minerals

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Industrial steam plants often extend across largeareas. Recovering condensate from steam systemsrequires piping, collecting tanks, pumping equip-ment, and, in many cases, flash steam separators,

meters, and filtration/cleanup equipment.However, the cost savings available from avoidingthe purchase, treatment, and heating of makeupwater often make investments in condensaterecovery systems highly feasible.

For more information on condensate recovery, seethe Steam Tip Sheet Number 8 titled ReturnCondensate to the Boiler, provided in Appendix B.

Condensate Return PipingCondensate return piping transports condensate asit drains from distribution and end-use equipmentpiping back to the boiler. Condensate piping shouldbe adequately sized and insulated. Although theinstallation of larger pipe diameters is moreexpensive, larger pipes create less pressure drop

for a given flow rate; this reduces the load on thecondensate pumps. Larger pipe diameters alsoreduce the noise associated with condensate flowand are more suitable for carrying flash steam.Insulating the condensate piping helps to retain thethermal energy that provides much of the benefitsof a condensate recovery system.

InsulationInsulation provides energy savings and safety benefits.In terms of energy savings, insulation reduces heatloss from the condensate piping and recovery equip-ment surfaces, which can make the surroundingwork environment more comfortable. Reducingthis heat loss can also reduce the burden on thecooling systems that support surrounding workspaces.

In terms of safety, insulation reduces the outer surfacetemperature of the piping, which lessens the riskof burns. Important insulation properties andcharacteristics of piping insulation are discussedin the Distribution section of this Sourcebook.

Condensate Recei er Tanks

especially during system startups. Recminimize the effects of this flow variacondensate pumps by providing storamaintains a minimum water level thadownstream condensate pumps fromSince many condensate pumps are ce

it is important to keep a certain suctioprevent cavitation damage. By maintminimum condensate level, receiver enough static pressure to avoid cavita

Most systems also contain a large conreceiver tank that collects all the conreturned from the system. This tank m

used to store pretreated water.

Condensate PumpsCondensate pumps move condensatetanks back to the boiler room. Condecan be driven by electric motors, steacompressed air, depending on the avthese sources. Motor-driven condensausually centrifugal type pumps. In mareceiver tanks and motor driven pumpackaged together and equipped witsystem that de-energizes the pump uwater level conditions. Steam or compowered condensate pumps are usedelectrical pumps would not be suitab

Figure 13. Condensate Receiver Tank Combination

CondensateReceiver

Tank

Inlet

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control and reducing potential equipment problemsfrom condensate acidification and water hammer.

Flash Steam VesselsFlash steam vessels allow the recovery of steamfrom condensate lines as illustrated in Figure 14.By removing steam from the condensate system,flash steam vessels provide an efficient source of

steam to low-pressure end uses. For example,250F condensate has a saturation pressure ofabout 15 psig. Consequently, steam that isseparated by flash steam vessels can be used inlow-pressure steam applications such as spaceheating and preheating.

For more information on flash steam vessels, seethe Steam Tip Sheet Number 12 titled Flash High-

Pressure Condensate to Regenerate Low-PressureSteam provided in Appendix B.

Condensate MetersCondensate meters measure the flow rate ofcondensate in the return system Knowing the

Filtration/Cleanup EquipmIn many systems, the flow of stepicks up rust, scale, and trace care either carried over from thein carbon steel piping and on cexchange surfaces. Although stare used to catch the particulatcontaminants are dissolved in t

can cause problems if returnedsystems that require a high levecondensate polishers are used. Cuse ion exchange to remove thpreventing the redeposition of ton boiler surfaces.

Figure 14. Flash Steam Recovery Vessel

SaturatedVapor Supply

Steam Trap

High-PressureCondensate

LevelController

Low-PressureFlash Vessel

SaturatedVapor

Saturated

Liquid

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Performance Improvem

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Overview

This section of the Sourcebook discusses importantfactors that should be considered when industrialfacilities seek to improve steam system performanceand to lower operating costs. Improving steam

system performance requires assessing the entiresystem, identifying opportunities, and selectingand implementing the most feasible projects. Inturn, this requires a systems approach. Similarly,proper selection of the best projects requiresquantifying the benefits and costs of each project.Successful implementation of these projectsrequires the participation of all system stakeholders

including production, maintenance, and manage-ment. Generally, obtaining managementparticipation requires communication of the analysesin economic terms. To address these considerations,this section of the Sourcebook discusses:

The systems approach;

Common performance improvementopportunities;

Resources that can assist to identify and assessopportunities; and

The economics related to steam systemimprovements.

Systems Approach

Because of the many industrial uses for steam,there are wide ranges of steam system sizes,configurations, end-use applications, and operatingpractices. As a result, there are many different waysto improve steam system performance and toidentify improvement opportunities. In general,

operators are so focused on the of the equipment that they oveissue of how system parameterment. Similarly, a common engis to break a system down into ior modules, optimize the selec

these components, and then ascomponents to form the systemthis approach is that it simplifieHowever, a disadvantage is thatthe interaction of these componesystems approach evaluates the determine how the end-use reqmost effectively and efficiently

A systems approach also recogefficiency, system reliability, anclosely related. For example, asuch as heat loss across uninsureduces energy available to therequires boilers to work harderdemand. Often, energy losses csystem stresses that accelerate w

create loads for which the systedesigned.

Common PerfoImprovement Opp

Several steam system improvemare common to many industriaopportunities can be categorizepart of the system in which theCommon performance opportugeneration, distribution, and resteam system are listed in Table

Section 2: Performance Improvement

Opportunities

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installed to make the process more efficient; forexample, multiple-stage dryers are often moreefficient than single-stage dryers. However, ingeneral, optimizing the efficiency of steam-suppliedend uses requires a case-by-case assessment.

B tP ti St S t

and tools are described in this section Sourcebook. Additional steam improvresources and tools are identified in tsection of the Sourcebook.

Steam System Scoping Tool

Opportunity Description

Generation

Minimize excess air Reduces the amount of heat lost up the stack, allowing more of thto be transferred to the steam

Clean boiler heat transfer surfaces Promotes effective heat transfer from the combustion gases to th

Install heat recovery equipment Recovers available heat from exhaust gases and transfers it back (feedwater economizers and/or system by preheating feedwater or combustion aircombustion air preheaters)

Improve water treatment to minimize Reduces the amount of total dissolved solids in the boiler water, w

boiler blowdown less blowdown and therefore less energy loss

Recover energy from boiler Transfers the available energy in a blowdown stream back into theblowdown thereby reducing energy loss

Add/restore boiler refractory Reduces heat loss from the boiler and retores boiler efficiency

Optimize deaerator vent rate Minimizes avoidable loss of steam

Distribution

Repair steam leaks Minimizes avoidable loss of steam

Minimize vented steam Minimizes avoidable loss of steamEnsure that steam system piping, Reduces energy loss from piping and equipment surfacesvalves, fittings, and vessels are wellinsulated

Implement an effective steam-trap Reduces passage of live steam into condensate system and prommaintenance program operation of end-use heat transfer equipment

Isolate steam from unused lines Minimizes avoidable loss of steam and reduces energy loss from equipment surfaces

Utilize backpressure turbines instead Provides a more efficient method of reducing steam pressure for of PRVs services

Recovery

Optimize condensate recovery Recovers the thermal energy in the condensate and reduces the amakeup water added to the system, saving energy and chemicals

Use high-pressure condensate to Exploits the available energy in the returning condensatemake low-pressure steam

Table 2. Common Performance Improvement Opportunities for theGeneration, Distribution, and Recovery Parts of Industrial Steam Systems

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The Steam System Scoping Tool contains sevenworksheets:

1. Introductionprovides instructions on how to

use the guide and what is indicated by theresults.2. Basic dataprompts the user to answer general

questions such as the amount of fuel used,amount of steam generated, and other generalsystem data.

3. System profilingassesses how the user trackssteam costs, benchmarks steam use, andmeasures important general operating parameters.

4. Operating practices of the total systemqueriesthe user regarding practices such as trapmaintenance, water treatment, insulationcondition, leak repair, and general equipmentinspection.

5. Operating practices of the boiler plantqueriesthe user on boiler efficiency, heat recoveryequipment, steam quality, and general boiler

operation.6. Operating practices of the distribution, end-use,

and recovery portions of the steam systemqueries the user about the use of pressurereducing valves, condensate recovery, and theuse of condensate to generate low-pressuresteam.

7. Summary sheetprovides scores based on userresponses.

Steam System Survey GuideThe Steam System Survey Guideis a referencedocument that is intended for use by plant energymanagers and system operations personnel. TheSurvey Guide provides a technical basis foridentifying and assessing many potential steamsystem improvement opportunities. Although

several of these opportunities can be identifieddirectly with the survey guide, others require moresophisticated measurements and data gatheringmethods.

The Scoping Tool and the Survey Guide are

system improvement opportuniare available from DOEs OfficTechnologies (OIT) BestPracticewww.oit.doe.gov/bestpractices.

offers links to other resources thusers in improving the performefficiency of their energy-inten

3E Plus Insulation AppraisBecause insulation is used in evits restoration, replacement, or common improvement opportuawareness regarding the energyassociated costs often results inof restoring or properly installinsteam system surfaces. As a resprogram known as 3E Plus wasNorth American Insulation Manu(NAIMA). The program increasamong steam system operationpersonnel of the benefits of ins

these stakeholders in assessing opportunities.

3E Plus assists the user in assesinsulation project factors such installation cost, and payback pinsulation materials and thickn3E Plus can estimate energy loss

surfaces as well as potential savinsulation options.

The program has general data fby type and can analyze insulathat use several different insulaaccounts for labor rates and proestimating how difficult the inswill be based on general piping

Users can quickly determine thfeasibility of various insulation tprogram also allows the user tocombinations of insulation typethe user optimize the material tan insulation system Downloa

Performance Improvement Opportunities: BestPractices Steam Tools, Financing Steam System I

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that offers certification to professionals whoconduct insulation appraisals or specify insulationrequirements. This program is intended to providecredibility to insulation professionals and to

increase consistency of the message that ispresented to clients. This program has four keycomponents:

Awareness Buildingan important way toincrease awareness of the potential cost savingsfrom insulation projects is to effectively promoteinsulation appraisal as a professional service.

Information Gatheringdetermining the parts of

the system that have the most attractive insulationimprovement opportunities usually requiresinput from the plant personnel. Improving theinterview techniques of insulation professionalscan increase the usefulness of these assessments.

3E Plusthe 3E Plus program is an importanttool for insulation professionals and specifyingengineers. Learning to effectively use this tool

can improve the quality of the assessmentfindings, presentation of recommendations, andcost-effective specification of new insulation.

Reportingaccurately and effectively reportingthe results of an insulation assessment cansignificantly increase the probability that therecommendations will be implemented.

Information regarding the Insulation Energy AppraisalProgram (IEAP) can be obtained from the NIA,99 Canal Center Plaza, Suite 222, Alexandria, VA22314, or from their Web site at www.insulation.org.

Steam Tip SheetsSome improvement opportunities are available tomany different systems. To increase industryawareness of several fundamental improvementopportunities, OIT has developed steam tip sheetsthrough its BestPractices Program.

These steam tip sheets provide concise descriptionsof common improvement opportunities. BecauseBestPractices continues to develop and identify

Overview of FinancSteam System Improve

Very often, industrial facility manageconvince upper management that an in steam efficiency is worth the effortcommunication of this message can odifficult than the actual engineering bconcept. The corporate audience wilmore readily to an economic impact discussion of Btu, pounds of steam, aratios. By adopting a financial approafacility manager relates steam efficiencorporate goals. Collaboration with fcan yield the kind of proposal that is convince corporate officers who havword about capital investments such system upgrades.

Before laying out some recommenda

to justify steam improvement projectsto understand the world as the corpousually sees it.

Understanding Corporate PrioriCorporate officers are held accountabexecutive, a board of directors, and ashareholders, if the firm is publicly h

job of these officers to create and grovalue of the firm. The corporations ifacilities do so by generating revenuethe cost of owning and operating thePlant equipmentincluding steam synentsare assets that must generate return. The annual earnings attributabof goods produced by these assets, dvalue of the plant assets themselves, deof return on assets. This is a key meacorporate decision-makers are held a

Financial officers seek investments thcertain to demonstrate a favorable reWhen faced with multiple investment

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surprises by sticking with familiar technology andpractices, and contribute to cost control today bycutting a few corners in maintenance and upkeep.This may result in industrial decision-makers

concluding that steam efficiency is a luxury thatcannot be afforded.

Fortunately, our story does not end here. Whatfollows is a discussion of ways that industrial steamefficiency can save money and contribute tocorporate goals while effectively reducing energyconsumption and cutting noxious combustionemissions.

Measuring the Dollar Impact of Steam

EfficiencySteam efficiency improvements can move to thetop of the list of corporate priorities if the proposalsrespond to distinct corporate needs. Corporatechallenges are many and varied, which in turnopens up more opportunities to sell steam

efficiency as a solution. Steam systems offer manyopportunities for improvement; the particulars areshared elsewhere in this Sourcebook. Once theselections are made, the task is one of communi-cating the proposals in corporate financiallanguage.

The first step is to identify and enumerate the total

dollar impact of a steam efficiency measure. Oneframework for this is known as life-cycle costanalysis. These analyses capture the sum totalof expenses and benefits associated with an invest-ment. The resulta net gain or loss on balancecan be compared to other investment options or tothe anticipated outcome if no investment is made.As a comprehensive accounting of an investmentoption, the life-cycle cost analysis for a steam

efficiency measure would include projections of:

Search and selection costs for seeking anengineering implementation firm;

Initial capital costs, including asset purchase,i t ll ti d t f b i

Scrap value or cost of disposequipments economic life;

Impacts on production suchand downtime.

One revelation that typically emexercise is that fuel costs may ras 96 percent of life-cycle costscapital outlay is only 3 percenta mere one percent. These findboilers with a 20-year life operof capacity utilization. Clearly, reduces fuel consumption (whil

reliability and productivity) wilpositive financial impacts for th

Financing Steam EfficiencAs with any corporate investmeways to measure the financial iefficiency investments. Some mcomplex than others are, and p

several analytical methods sidechoice of analyses used will desophistication of the presenter

A simple and widely used meaeconomics is the payback perioas the period of time required fbreak even. It is the time neebenefits of an investment to accwhere they equal the cost of thFor a project that returns benefannual increments, the simple initial investment divided by thSimple payback does not take time value of money; in other wdistinction between a dollar eadollar of future (and therefore u

Still, the measure is easy to useand many companies use simpquick go/no-go decision on aimportant factors to remember simple payback:

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Payback calculations will not always find thebest solution (for the two reasons immediatelyabove) when choosing among several projectoptions; and

Payback does not consider the time value ofmoney or tax consequences.

More sophisticated analyses take into accountfactors such as discount rates, tax impacts, the costof capital, etc. One approach involves calculatingthe net present value of a project, which is definedin the equation below:

Net present value = Present worth of benefits Present worth of costs

Another commonly used calculation for determiningeconomic feasibility of a project is internal rate ofreturn, which is defined as the discount rate thatequates future net benefits (cash) to an initialinvestment outlay. This discount rate can be

compared to the interest rate at which a corporationborrows capital.

Many companies set a threshold (or hurdle) rate forprojects, which is the minimum required internalrate of return for a project to be considered viable.Future benefits are discounted at the thresholdrate, and the net present worth of the project mustbe positive in order for the project to be a go.

Relating Steam Efficiency to Corporate

PrioritiesSaving money, in and of itself, should be a strongincentive for adopting steam efficiency. Still, thatmay not be enough for some corporate observers.The facility managers case can be strengthenedby relating a positive life-cycle cost outcome tospecific corporate needs. Some suggestions forinterpreting the benefits of fuel cost savingsinclude the following (finance staff can suggestwhich of these approaches are best for the currentcorporate climate):

the steam efficiency investment is borrowing, retained earnings, or thfinancingthe annual savings wilpermanent source of funds as long

efficiency savings are maintained obasis.

Added shareholder value. Publiclycorporations usually embrace oppenhance shareholder value. Steamcan be an effective way to captureShareholder value is the product ovariables: annual earnings and theearnings (P/E) ratio. The P/E ratio dthe corporations stock value as thstock price divided by the most reearnings per share. To take advantmeasure, the steam efficiency propfirst identify annual savings (or ratto earnings) that the proposal will Multiplying that earnings incremeratio yields the total new sharehol

attributable to the steam efficiency im Reduced cost of environmental co

Facility managers can proactively the corporations exposure to penato environmental emissions compefficiency, as total-system disciplinbetter monitoring and control of fuCombustion emissions are directly

fuel consumption: they rise and faBy implementing steam efficiency, tenjoys two benefits: decreased fuelper unit of production, and fewer emission-related penalties.

Improved worker comfort and safsystem optimization requires ongoiand maintenance that yields safetybenefits in addition to fuel savingsinvolved in system monitoring will uoperational abnormalities before tdanger to plant personnel. Containdangers precludes threats to life, hproperty.

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promise more reliable plant operations. The flipside, from the corporate perspective, is a greaterrate of return on assets employed in the plant.

Call to ActionA proposal for steam efficiency implementation

can be made attractive to corporate decision-makersif the facility manager:

Identifies opportunities for achieving steamefficiency;

Determines the life-cycle cost of attaining eachoption;

Identifies the option(s) with the greatest netbenefits;

Collaborates with financial staff to identifycurrent corporate priorities (for example, addedshareholder value, reduction of environmentalcompliance costs, and improved capacityutilization); and

Generates a proposal that demonstrates how thesteam efficiency projects benefits will directlyrespond to current corporate needs.

SummaryIncreased awareness of the potential improvementsin steam system efficiency and performance is animportant step toward increasing the competitivecapabilities of energy-intensive industries. Some

of the useful steam resources and tools developedby BestPractices have been described in this section.Additional steam resources and tools and where toobtain them are described in the Resources andTools section of this Sourcebook.

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Programs, Contacts, and Resources: OIT

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This portion of the Sourcebook lists resources thatcan help end users increase the cost-effectiveperformance of steam systems. The section isorganized into three sections, described below:

Programs

This section describes the U.S. Department ofEnergys Office of Industrial Technologies (OIT)BestPractices Program, a national effort aimed atimproving the performance of industrial steamsystems. This section provides a list of associationsand other organizations involved in the steamsystem marketplace.

ContactsThis section provides a list of associations andother organizations involved in the steam systemmarketplace.

ResourcesThis section provides information on books andreports, other publications, government and

commercial statistics and market forecasts,software, training courses, and others sources ofinformation that can help end users make informedsteam system equipment purchase and systemdesign decisions.

OIT and BestPractices

OverviewIndustrial manufacturing consumes 36 percent ofall energy used in the United States. OIT hasprograms to assist industry in achieving significantenergy and process efficiencies. OIT develops anddelivers advanced energy efficiency renewable

a vision of their future and roadachieve these visions over a 20This collaborative process alignwith federal resources to acceledevelopment of advanced techas priorities by industry.

The advancement of energy- antechnologies is complemented management best practices for results. OITs BestPractices assiIndustries of the Futureagricuchemicals, forest products, glasmining, petroleum, and steel

realize their best energy efficieprevention options from a systecost perspective. Through activplant-wide energy assessments,emerging technologies, and enindustrial systems, BestPracticesolutions for industry that result and cost savings, waste reductiprevention, and enhanced envi

performance.

Plant AssessmentsDepending on the industry, ene10 percent or more of total opeassessments identify opportunitnew technologies and system imrecommendations from energy

payback periods of less than 18result in significant energy savi

Plant-wide assessments helpdevelop comprehensive planincrease efficiency reduce e

Section 3: Programs, Contacts, and Resour

E i T h l i P h f ll l

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Emerging TechnologiesEmerging technologies are those that result fromresearch and development and are ready for full-scale demonstration in real-use applications. OIT

recognizes that companies may be reluctant toinvest capital in these new technologies, eventhough they can provide significant energy andprocess improvements. However, through technologyimplementation solicitations, OIT helps mitigatethe risk associated with using new technologiesthat are supported by IOF partnerships. By sharingimplementation and providing third-partyvalidation and verification of performance data,

the energy, economic, and environmental benefitscan be assessed to accelerate new technology toacceptance.

Energy ManagementOIT encourages manufacturers to adopt acomprehensive approach to energy use thatincludes assessing industrial systems and evaluating

potential improvement opportunities. Efficiencygains in compressed air, motor, process heating,pumping, and steam systems can be significantand usually result in immediate energy and costsavings. OIT offers software tools and training in avariety of system areas to help industry becomemore energy and process efficient, reduce waste,and improve environmental performance.

Allied PartnershipsAllied Partners are manufacturers, associations,industrial service and equipment providers,utilities, and other organizations that voluntarilywork with OIT. Allied Partners seek to increaseenergy efficiency and productivity for thoseindustries that participate in OITs Industries of theFuture strategy by participating in, endorsing, andpromoting OIT programs, products, and services.Allied Partnerships help OIT achieve industrialenergy efficiency goals by extending deliverychannels through the partners existing networks.In turn, partners realize benefits, such as achieving

Partners who successfully complete tqualifying exam on the use of OIT soprograms are recognized as QualifiedFor more on Allied Partnerships, conClearinghouse at 800-862-2086.

Technical ResourcesOIT offers a variety of resources to heachieve increased energy and procesimproved productivity, and greater co

OIT Clearinghouse. The OIT Clearinghquestions on OIT products and servic

those focused on the Industries of theThey can also answer questions abousystems such as compressed air, motoheating, and steam. The OIT Clearingthe first stop in finding out whats avaOIT. Contact the Clearinghouse at 80or clearinghouse@ee.doe.gov.

OIT and BestPractices Web Sites. The BestPractices Web sites offer a large information, products, and resources manufacturers who are interested in efficiency of their industrial operationgain access to Web pages for the ninthe Future, learn about upcoming evesolicitations and much more throughVisit the OIT site at www.oit.doe.gov

The BestPractices site offers case studiesthat have successfully implemented entechnologies and practices, software sheets, training events, and solicitatioassessments. You can see these and oat www.oit.doe.gov/bestpractices.

Software Tools and Training. OIT and have developed several software toolimprovements to help you make decimplementing efficient practices in yomanufacturing facilities. Tools for assefficienc of fan and process heating

d l i i d ff i f Di t f C

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and evaluating savings and effectiveness ofenergy efficiency measures.

An energy-efficient motor selection and management tool, MotorMaster+ 3.0 software includes

a catalog of over 20,000 AC motors. Version 3.0features motor inventory management tools,maintenance log tracking, efficiency analysis,savings evaluation, energy accounting, andenvironmental reporting capabilities.

The Pumping System Assessment Tool (PSAT)helps industrial users assess the efficiency ofpumping system operations. PSAT uses achievablepump performance data from Hydraulic Institutestandards and motor performance data from theMotorMaster+ database to calculate potentialenergy and associated cost savings.

The Steam System Scoping Tool is designed tohelp steam system energy managers andoperations personnel for large industrial plants.

This spreadsheet program will profile and gradesteam system operations and management. Thistool will help you to evaluate your steam systemoperations against identified best practices.

With 3E Plus software you can easily determinewhether boiler systems can be optimized throughthe insulation of boiler steam lines. The program

calculates the most economical thickness ofindustrial insulation for a variety of operatingconditions. You can make calculations using thebuilt-in thermal performance relationships ofgeneric insulation materials or supply conductivitydata for other materials.

Training session