FiredHeaters
BY
Hampa Energy
Engineering & Design Company
(HEDCO)
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In the Name of God
Introduction
Combustion Radiation Convection Conduction Mechanical design
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IntroductionVERTICAL‐CYLINDRICAL FIRED HEATERS The most common type Duties up to about 45 MW
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IntroductionHORIZONTAL TUBE CABIN FIRED HEATERS Not economical under about 35 MW Duties up to about 145 MW Rather large footprint Only for special services
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IntroductionVERTICAL TUBE BOX FIRED HEATERS Two‐side fired tubes Suited for the large forced‐draft burners Steam reformer fired heaters
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Introduction
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IntroductionHeat balance:
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Introduction
Heat balance:
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BurnersTypes: Premix Raw‐gas Staged (low NOx)
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BurnersFlame: Luminous Non‐luminous
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Radiant sectionRadiant heat transfer: Thermal equilibrium, Kirchoff ’s law:
Emissivity:
1
4 2, ( / )blackblack
E E T W mE
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Radiant sectionHottel’s well‐stirred modelSimplifications: Single temperature Combustion gas is grey Surface of heat sink is grey Negligible convection Speckled wall assumption
BW gT T
gT
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Radiant sectionRefractory:
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Radiant sectionRefractory: Internal insulation Re‐radiation
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Convection sectionCross flow H.E.
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Convection sectionShield and bare tubes: 2 rows shield tubes At least 3 bare rows
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Convection sectionExtended surface tubes: Increase H.E. area
Up to 12 times
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DraughtCompensate for pressure drops: Natural draft Forced draft
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Tube design
Tube metal temperature
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Tube designElastic design: Elastic allowable stress Thermal stress
Creep rupture: Rupture strength for a design life
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Tube supportsRadiant section
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Tube supports
Convection section
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Sketch - A relatively small heater
8 MW start‐up heater All radiant heater Vertical tubes
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Sketch-A relatively large heater
25 MW crude oil heater Horizontal tubes
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www.hedcoint.comWeb site: [email protected]: -E
Tel: (+98) 71- 32136000Fax: (+98) 71- 32136527
Thank You
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