Hydraulics of Kettle-Reboiler Circuit on Distillation Columns

Transcription

1 Fractionation Research, Inc. RESEARCH KEY TO BETTER DESIGN Hydraulics of Kettle-Reboiler Circuit on Distillation Columns Tony Cai, Mike Resetarits, and Ahmad Shariat Fractionation Research, Inc. Distillation Honors Session: Professor Michael Schultes 2010 AIChE Annual Meeting, Salt Lake City, UT November 9, 2010

2 Slide 2 Dr. Schultes at FRI Experimental Unit in 1998

3 Slide 3 Dr. Schultes at FRI Experimental Unit in 2010

4 Slide 4 Dr. Schultes at FRI Experimental Unit in 2010

5 Captain Dr. Schultes Slide 5

6 Fractionation Research, Inc. RESEARCH KEY TO BETTER DESIGN Hydraulics of Kettle-Reboiler Circuit on Distillation Columns Tony Cai, Mike Resetarits, and Ahmad Shariat Fractionation Research, Inc. Distillation Honors Session: Professor Michael Schultes 2010 AIChE Annual Meeting, Salt Lake City, UT November 9, 2010

7 Introduction 7 Reboilers are commonly used heat exchangers on distillation columns, supplying most of the energy required for the column It is very important to properly design and operate the overall reboiler circuit o If too much heat is supplied, the tower will flood; too little heat is available, separation performance decreases Significant ifi number of fractionator t problems can be attributed to either improper bottom circuit design or poor reboiler circuit layout Reboiler problems are thought to be the second-most common cause of tower problems

8 Typical Kettle Slide 8

9 Problems & Objectives 9 Tower bottom hydraulics is not generally investigated as mush much as mass transfer is This paper focus on the hydraulics of kettle reboiler circuits Experimental results are compared to analytical predictions

10 Approaches 10 Pressure drops of vapor phase between the reboiler and the column were measured using differential pressure transmitter The liquid level at the bottom of the column was measured using a bubbler Pressure drops of liquid and vapor phases across the reboiler circuit were calculated/estimated using basic fundamental fluid dynamics

11 FRI Experimental Unit Slide 11 LP Reboiler HP Reboiler

12 Kettle Slide 12 Return Line Reboiler

13 Locations of Pressure Drop Measurements 13 DP Line

14 Location of Bubbler 14 Bubbler Line DP Line

15 Pressure Transmitter 15 DP Transmitter

16 Results Slide 16

17 Standard Kettle Slide 17 P Vapor P Liquid

18 Slide 18 Reboiler Pressure Drop (Vapor Phase) ic 4 /nc psia (11.4 bar) Capacity Factor C S, m/s inch H 2 O Capacity Factor C S, ft/s Measured Reboiler DP

19 Slide 19 Reboiler Pressure Drop (Vapor Phase) ic 4 /nc psia (11.4 bar) 5.0 inch H 2 O Return Line Velocity, ft/s Measured Reboiler DP

20 Slide 20 Reboiler Pressure Drop (Vapor Phase) ic 4 /nc psia (11.4 bar) inch H 2 O Capacity Factor C S, ft/s Measured Reboiler DP Calculated Reboiler DP

21 Slide 21 Reboiler Pressure Drop (Vapor Phase) ic 4 /nc psia (11.4 bar) inch H 2 O Return Line Velocity, ft/s Measured Reboiler DP Calculated Reboiler DP

22 Slide 22 Column Bottom Liquid Levels ic 4 /nc psia (11.4 bar) inch Hot Liqui id Capacity Factor C S, ft/s Measured Column Bottom Level

23 Slide 23 Column Bottom Liquid Levels ic 4 /nc psia (11.4 bar) inch Hot Liqui id Return Line Velocity, ft/s Measured Column Bottom Level

24 Slide 24 Rise of Column Bottom Liquid Level ic 4 /nc psia (11.4 bar) inc ch Hot liqui id Capacity Factor C S, ft/s Rise of Column Bottom Level

25 Slide 25 Rise of Column Bottom Liquid Level ic 4 /nc psia (11.4 bar) inc ch Hot liqui id Return Line Velocity, ft/s Rise of Column Bottom Level

26 Slide 26 Rise of Liquid Level and Reboiler Pressure Drop ic 4 /nc psia (11.4 bar) inc ch Hot liqui id Capacity Factor C S, ft/s Measured Reboiler DP Rise of Column Bottom Level

27 Slide 27 Rise of Liquid Level and Reboiler Pressure Drop ic 4 /nc psia (11.4 bar) inc ch Hot liqui id Capacity Factor C S, ft/s Measured Reboiler DP Rise of Column Bottom Level Caculated Total Pressure Drops

28 Slide Reboiler Pressure Drop (Vapor Phase) C 6 /C 7 5 psia (1.65 bar) 20.0 in H 2 O Pres ssure Drop, Capacity Factor Cs, ft/s Calculated Measured

29 Slide Reboiler Pressure Drops (Vapor Phase) C 6 /C 7 5 psia (1.65 bar) Pres ssure Drop, in H 2 O Capacity Factor Cs, ft/s Calculated Measured Calculated (with estimated entrainment)

30 Conclusions 30 Pressure drops across the reboiler circuit and liquid levels can be measured and monitored using differential pressure transmitters Measured pressure drops and liquid levels agree reasonably well with the calculated/estimated l ti t d values Pressure drop of fliquid idphase can be significant ifi portion of total pressure drops, which needs to be considered and included in the reboiler circuit designs

31 Acknowledgements 31 Authors would like to extend their great appreciations to: o FRI memberships for their continuous support to FRI research programs o Professor Michael Schultes for his excellent work and guidance to FRI research program as FRI Technical lcommittee member o Professor Olujic and Mr. Urbanski for their great work on this session

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