equipment heat loss · 2019-12-08 · equipment heat loss ford, bacon & davis, llc 5 ......

1Ford, Bacon & Davis, LLC

Equipment Heat Loss

• Review Examples Of Process Heat Transfer To Equipment Not Classified As Heat Exchangers (Fired Or Non‐fired)

• Look At Ways To Input Heat To Equipment For Process Heat Transfer

• Identify Heat Transfer Formulas For Equipment Process Heat Transfer

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• Prevent Condensing (Gas/Vapor Service)– Condensed Liquid May Cause Corrosion– Condensed Liquid May Create Downstream Operating Problems

• Prevent Solidification (Liquid Service)– Prevent Mechanical Damage To Pipe And Equipment Due To 

Freezing (Water Services)– Maintain Liquid State To Ensure Hydraulic Transfer

• Viscosity Control

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• Heat Transfer To Change – Fluid Temperature – Fluid State (Phase Change)– Fluid Properties

• Heat Transfer To Process (Heating)

• Heat Transfer From Process (Cooling)

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EquipmentHeat Loss

5Ford, Bacon & Davis, LLC

• CONDUCTION – Heat Loss Directly Through Equipment Materials And Materials In Contact With Equipment

• CONVECTION – Heat Loss Indirectly Through Fluid Boundary Layer at Equipment Or Insulation Surface

• RADIATION – Heat Loss Through Energy Wave Emission At Surface Exposed To Atmosphere

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Wet Wall

Dry Wall

Tp

TaRadiation

Convection

Conduction

Vw

Tw

tw

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Wet Wall

Dry Wall

Tp

TaRadiation

Convection

ConductionVw

Tw

tw

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Qc = Conduction Heat Transfer (Insulation)

Qv = Convection Heat Transfer (Jacket To Atmosphere)

Qr = Radiation Heat Transfer(Jacket To Atmosphere)

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1/hc = Insulation Thickness/ Insulation Thermal Conductivity

ha = hv + hr= Convection Coefficient + Radiation Coefficient

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Insulation Saves Energy – Chemical Engineering, 05/27/74

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Convection Coefficient Radiation Coefficient

Atmospheric Coefficient

Wind Speedmph

SurfaceTemperature

°F

AmbientTemperature

°F

hacBtu/hr/ft2/⁰F

0 100 20 0.890 200 20 1.1

10 100 20 3.310 200 20 4.020 100 20 4.620 200 20 5.630 150 20 6.340 150 20 7.2

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Emissivity SurfaceTemperature

°F

AmbientTemperature

°F

harBtu/hr/ft2/⁰F

0.50 100 20 0.490.50 200 20 0.660.70 100 20 0.690.70 200 20 0.920.90 100 20 0.890.90 200 20 1.21.0 100 20 0.981.0 200 20 1.3

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EquipmentHeat Gain

19Ford, Bacon & Davis, LLC

• CONDUCTION – Heat Transfer To Equipment Through Equipment Materials And Materials In Contact With Equipment

• CONVECTION – Heat Transfer At Fluid Boundary Layers Inside And Outside Of Equipment And Heat Exchange Attachments In Contact With Equipment

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• Temperature Maintenance

Heat Gain = Heat Loss

• Process Heat Transfer

Heat Gain > Heat Loss

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EquipmentHeat Transfer Attachments

26Ford, Bacon & Davis, LLC

Option Internal External Attached Integral

Heat Exchange Insert

Bayonet ExchangerPipe CoilMixing EductorSparger

X X

Jacket FullHalf Pipe

X X

Tracers ElectricPipeTubingControTrace

X X

Plate Coil X X

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Spiral Serpentine

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Koch TF Armstrong BHC/BHS

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OUTLET

INLET

Liquid Service Steam Service

INLET

OUTLET

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Spiral Baffle

OUTLET

INLET

INLET

OUTLET

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INLET

OUTLET

Spiral Baffle

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Pfaudler Agitating Nozzle

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Pfaudler RS‐48

HT Fluid:  Water

Nozzles Required:  2

Nozzle Size:  1.5 in.

dP:  20 psi

Total Flow: 68 gpm

hj =  548 Btu/hr‐ft2‐⁰F

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Thermon BSX

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Thermon RT Flexipanel

• Heat Duty In Watts Per Foot For Cable Or Watts Per Square Inch For Panels

• Self‐Regulating Feature Available

• For Offsite Location, Electricity May Be More Available Than Other Energy Sources

• Remote Monitoring And Control Possible

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• Tubing Is Easier To Bend To Follow Equipment Contours Particularly Heads and Nozzles

• Selection of Pitch (Distance Between Runs) Is Critical To Ensure Wall Temperature Stays Above Minimum Maintain Temperature

• Design Of Tubing Heat Tracing Is Typically The Engineering Contractor Responsibility

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Tranter

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Clamp‐On Jacket

• Manufactured Assembly Takes Less Labor To Install Than Pipe Or Tubing Tracers

• Tubing Tracer Installed At Fabricator May Be Damaged During Shipping – Coil Assembly Is Typically More Rugged Design

• Heat Transfer Design Is Typically Coil Assembly Vendor Responsibility

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• Understand Process Objective:– Temperature Maintenance– Process Heat Transfer

• Selection Of Heat Transfer Components For Equipment Should Be Based On:– Level Of Heat Transfer Requirement – Process Considerations– Cost

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