Heat Exchanger Presentation

Shell and Tube Heat Exchanger October 7, 2003 Cycle 2 Group 1A Frank Fadenholz Jennifer Fadenholz Christian Woods Angel Taylor

Outline • Objectives • Background • Experimental Strategy • Results • Error Analysis • Conclusions • Recommendations • References

Objectives and Background

Objectives • Operate shell and tube heat exchanger varying steam flow

• Determine the outside overall heat transfer coefficient (Uo)

• Determine shellside heat transfer (QSS ) • Determine tubeside heat transfer (QTS )

Heat Exchanger Background • Exchange heat between fluids • Latent heat and sensible heat transfer • Common to chemical process industry • Types of heat exchangers – – – –

Air Cooled Double Pipe Spiral Plate and Tube Shell and Tube

Heat Exchanger Background Shell and Tube Heat Exchangers

• Account for 60% of heat exchangers in use today • Can handle large flows, low temperatures and pressures, high temperatures and pressures

• Our shell and tube heat exchanger – Basco Type 500 U-tube Water Heater – 1 Shell Pass – 16 Tubes

Experimental Strategy

Cold Water Inlet

Compressed Air

Steam

ST-V4

Emergency Shutdown Valve

ST-V1

ST-V3

ST-V2

Emergency Shutdown Vavle

TV-04

Should make Labels Larger

FT-01

PRV-05 TT-04

Hot Water Outlet

TT-03

PG-07

Condensate

E-01

T ST-V5

PG-06

FT-02

FV-02

Figure 1. Unit Operations Lab: Shell and Tube Heat Exchanger (Group 1A)

Experimental Strategy • 5 Runs Total • Varied Steam Valve (TV-04) Position – – – – –

105% open 75% open 65% open 60% open 52% open

• Cooling water flow rate constant

Experimental Strategy • Measured Variables – – – – –

Condensate flow Condensate temperature Cooling water flow Cooling water inlet temperature Cooling water outlet temperature

Heat Exchanger Calculations • Heat transfer rate

• QTS = mCp∆ T • QSS = m∆ H + mCp∆ T

• Overall heat transfer coefficient • Uo = QSS /(Ao*∆ TLM )

• Log mean temperature • ∆ TLM =

((Thi -Tco ) – (Tho – Tci )) / ln[(Thi – Tco ) – (Tho – Tci )]

Simplified Process Flow Diagram Thi

Qin, SS Tci

Qin, TS

Qout, TS Qout, SS

Tho

Tco

Results

Experimental Results Steam Valve Heat Transfer Heat Transfer % Open Rate (QTS ) Rate (QSS ) (btu/hr) (btu/hr)

Overall Heat Transfer Coefficient (Uo) (btu/lb*F*hr)

105%

276489

275350

211

75%

250275

254588

201

65%

183357

181872

148

60%

134200

133777

112

52%

98289

93757

78

Shellside vs. Tubeside Heat Transfer He at Tr anfe r Rate (Q) Q-tube s ide vs . Q-s he lls ide

Q tubeside (btu/hr)

290000 240000 190000 140000 90000 75000

125000

175000

Qsh ellsid e (btu/hr)

225000

275000

Hate Transfer Rate (btu/hr)

Steam vs. Heat Transfer Rate (QTS , QSS ) 290000 240000 190000 140000 90000 75

125 175 225 Condensate Mass Out (lb/hr) Q-Shellside

Q-Tubeside

275

Steam vs. Overall Heat Transfer Coefficient Heat Transfer Coefficient (btu/lb*F*hr)

300 250 200 150 100 50 50

100

150

200

250

Condensate Mass Out (lb/hr) U inside

U outside

300

Error Analysis

Propagation of Error • Determine the accuracy of measured

variables • Apply the propagation of error equation to each function

 k  ∂y   ∆y = ∑  ∆xi    i =1  ∂xi   2

1

2

Variable Measurement Accuracy

• Flow rate of the steam +/- 5 lb/hr • Flow rate of the cooling water +/- 50 lb/hr • Temperature readings +/- 2 °F • Largest sources of error

– Mass flow rate of the steam – Mass flow rate of the cooling water

Calculated Error Values • ∆QTS ≈ +/- 1,000 btu/hr • ∆QSS ≈ +/- 50,000 btu/hr • ∆Uo ≈ +/- 4 btu/lb °F hr • ∆Ui ≈ +/- 4 to +/- 1.6 btu/lb °F hr

Heat Transfer Rate (btu/hr)

Propagation of Error Heat Transfer 340000 290000 240000 190000 140000 90000 75

125

175

225

Condensate Mass Out (lb/hr) Q-tubeside

Q-shellside

275

Propagation of Error Heat Transfer Coefficient Heat Transfer Coefficient (btu/lb*F*hr)

300 250 200 150 100 50 50

100

150

200

250

Condensate Mass Out (lb/hr) U inside

U outside

300

Conclusions and Recommendations

Conclusions • QTS , QSS , Uo all increase as the steam flow rate increases

• QTS , QSS , Uo all have a linear relationship with the mass flow rate of the steam

• Heat transfer rate of the tube side is equal to the heat transfer rate of the shell side

Recommendations • Operation Recommendation – Operate the shell and tube heat exchanger at approximately 75% for sufficient heat transfer and economic efficiency

• Experiment Recommendations – Monitor pressure gauge (PG-07) at low steam rates to prevent a vacuum

References • API Heat Transfer. Shell and Tube Heat Exchanger Picture • • • •

www.apiheattransfer.com/en/Products/HeatExchangers/She llAndTube/ Georgia Tech. Propagation of Error. www.swiki.che.gatech.edu/CHE4200. August 2002. Geankoplis, Christie J. Transport Processes and Unit Operations, 3rd ed. Englewood Cliffs, NJ. Prentice-Hall Publishing, Inc. 1993. Heald, C. C. Cameron Hydraulic Data. Liberty Corner, NJ. Ingersoll-Dresser Pump Co. 1998. Peters, Timmerhaus, West. Plant Design and Economics for Chemical Engineers, 5th ed. New York, NY. McGaw-Hill Co. Inc., 2003.