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The Big Choice:

Steam Generator or Steam Boiler ?

A very important question to ask yourself. Are you in doubt about the exsactdifference in these two kind of steam producing plants, then it isrecommended that you read the below introduction. There is a difference, andit can gives you substantial advantages to choose right, both economical andtechnical.

Go directly to

CLASSICSTEAM BOILERS

Go directly to

STEAMGENERATORS

Go directly to EXHAUST GAS BOILERS

The theory of producing steam

Water and steam are typically used as heatcarriers in heating systems. It is well knownthat water boils and evaporates at 100Cunder atmospheric pressure.By higherpressure, water evaporates at highertemperature- e.g. a pressure of 10 barequals an evaporation temperature of184C. During the evaporation process,pressure and temperature are constant, anda substantial amount of heat are use forbringing the water from liquid to vapourphase. When all the water is evaporated,the steam is called dry saturated. In thiscondition the steam contains a largeamount of latent heat, corresponding theheat that was led to the process under

Steam generator versus steam boiler

Opposite the principle of the steam boilers,the water in the steam generatorsevaporates inside the tube winded up intoserial connected tube coils. The feed wateris heated up to the evaporationtemperature and then evaporated. Theintensity of the heat, the feed water flowand the size/length of the tube are adapted,so that the water is exactly fully evaporatedat the exit of the tube. This ensures a verysmall water and steam volume (content ofthe pressure vessel). Thus there are nobuffer in a steam generator, and is ittemporary overloaded i.e. beyond itsnominal steam capacity - a separate buffertank should be provided (accessories). The

The steam generators heaters are madewith coils made of seamless tubes, wherethe feed water is preheated and evaporatedduring the flow through these. The heat istransferred to the water/steam mixture asradiant heat in the combustion chamber,where the inner cylindrical tube coil and aflat tube coil forms the chamber wall and thebottom respectively. Consequentlyrefractory concrete is avoided. Thecombustion gasses are hereafter cooled inthe outer convection part, as the gassespass the space between the two tube coils.The thermal design ensures a modestvolume of steam relative to the size of theheater, and allows unlimited thermalexpansion due to the high temperatures. AllTT Boilers steam generators and steam

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constant pressure and temperature.

So despite temperature and pressure is the

same for the liquid and the vapour, theamount of heat is much higher in vapourcompare to the liquid. This latent heat in thedry saturated steam can efficiently beutilised to different processes requiringheat.

The steam boiler or steam generator isconnected to the consumers through thesteam and condensate piping. When thesteam is provided to the consumers, itcondensate. It can then be returned to the

feed water tank, from where it again ispumped to the steam boiler / steamgenerator. It often happens that thecondensate is not fully or partly recycled,and then a make-up of fresh and pre-treated feed water is established.

advantages using a steam generatorcompare to conventional steam boilers:

Easy to operate - normally no

requirement for boiler authorisation

Rapid start-up and establishing full

steam pressure Compact and easy to adapt in the

existing machinery arrangement Price attractive - especially at low

steam rates.

Steam Generator Design

Steam generators can be delivered inhorizontal execution (with low height), or invertical execution (occupying limited floorspace). Like the steam boilers they aredelivered insulated with stainless steelcover sheets and complete with burner,armatures, instrumentation, safeties and acontrol panel - and with full documentationincluding necessary certificates.

boilers are designed and equippedaccording to German TRD boiler regulationsand Danish AT boiler regulations (and

corresponding ratified EN-norms).

Beside the standard execution the steamgenerators can be delivered in e.g. followingvariations:

Electrical heated, including EX-

design if required Material in stainless steel Complete skid-mounted with tanks

and pretreatment equipment. Build in a container.

Exhaust Gas Boilers Economizers

Steam can be produced not only by oil orgas-fired burners, but also by utilizing thesubstantial amount of waste heat in hot fluegasses or exhaust air. The steamevaporation is done like the steam

generators, and are gives therefore a rapidacting and compact unit.