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RVP Control FCCU Debutanizer
This table shows actual plant survey data from an FCCU Debutanizer, compared with design and simulation data. Based on this data, Ascent was able to determine  equipment fouling was a major contributor to the bottom's RVP issues:

FCCU Debutanizer Data

         

Plant

     
 

Design

 

Survey

Simulation

         
FCCU charge, MBPSD

25

 

30.5

30.5

Debutanizer charge, MBPSD

31.1

 

29.5

29.5

Debutanizer reflux, MBPSD

14.6

 

11.2

11.0

Debutanizer OH prod, MBPSD

9.5

 

7.7

7.7

Debutanizer OH pressure, psig

165

 

155

155

         
Overhead C5+ purity, LV%

0.5

 

1.7

1.7

Bottom C4- purity, LV%

0.05

 

0.7

0.7

Bottom RVP    

7.0

7.7

Bottom API gravity    

58.5

58.3

         
Estimated flooding percentage

77

 

57

57

         
Condenser inlet temp, ° F

148

 

146

152

Condenser outlet temp, ° F

100

 

111

113

Amount of subcooling, ° F

19

 

8

8

Cooling water supply temp, ° F

80

 

65

65

Cooling water return temp, ° F

105

 

102

102

Condenser D Q, MMBTU/hr

29.1

 

23.8

23.8

LMTDc, ° F

36.5

 

50.8

50.8

Overall heat transfer coef., U

124

(1)

44.3

44.3

Cooling water flow rate, gpm

2,292

 

1,279

1,279

Cooling water D P, psi

8

 

22

3

 
(1) The unit was over-surfaced so that the U required was only 76.3.