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Boiler Construction, Pressure

Parts & Drum Internals

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Mittwoch, 4. September

2013

Fußzeilentext 2

Objectives and other details of modules

Duration – 75 minutes

Training aids

Power point Presentations

Reading Material

Objective

 At the end of the session par ticipants wi ll be able to :

Describe essential parts of boi ler and their functions

List out design cri teria of various pressure parts and furnace, materialof construction

Detail out of steam separation principles drum and its funct ion

contraction details of boiler drum

Distinguish between boilers for subcri tical and supercritical units

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Boiler Construction

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Pressure Parts arrangement

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Furnace design aspects

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This closeness in size reflects the fact that acoal-fired unit has to be designed to preventexcessive slagging, whereas an oil-fired unit has

to take into account, as a primary sizing factor,its furnace tube-wall integrity

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Furnace Design Considerations

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Important design considerations for the proper sizing of the furnace include

Net-heat-input-to-plan-area (NHI/PA) release rate. As the rank of coal decreases, furnacesincrease in plan area and vertical height from the top fuel nozzle to the furnace arch.The NHI/PAs range from (1.6 x 109 J/hr-929 cm2) for severe slagging coals,through (2.2 x 109 J/hr-929 cm2) for low slagging coals

Distance from the upper fuel nozzle level to the furnace exit. Sufficient furnace dimensions,

including adequate height between the top row of burners and the furnace exit, must beused to obtain the proper retention time for the combustion.

Furnace exit gas temperature (FEGT). Sufficient waterwall heat transfer surface is necessaryto allow sufficient cooling of the combustion gas so that the fly ash is solidified before itenters the first pendant tube bank.

This will minimize deposition and fouling of the pendant tube banks.

The velocity of the flue gas must not exceed specified limits in order to control erosion fromthe ash in the coal. Depending on the ash analysis and quantity, the velocity is generallylimited to (18.3 to 21.3 m/s).

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Furnace Sizing

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500MW construction details

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Boiler materials Consideration

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The primary consideration in material choice is a function of expected tube temperatureof operation.

Economizers and water wall sections are usually constructed with a mild or mediumcarbon steel, whereas

low alloy ferritic steels are used for most super heater and re heater sections,with austenitic stainless steels specified for the highest-temperature circuits or corrosionperformance.

Alloys for use as boiler tube materials in the United States are identified by an ASMEdesignation (SA-xxx) or an essentially equivalent

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Materials for Boiler 

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Boiler drum and steam separation

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Steam Generation

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Steam Generation

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Steam Separation

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Boiler steam water schemes

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Heat Transfer in a pipe

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Common Circulation systems

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Boiler Drum and internals

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Drum design cri teria

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Steam Drum

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Steam Drum and separators

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