Use of Yield Charts & Equations
Volume
Mass
Density
Ave BPT
Watson K
Hydrogen
For cracking
∆
Sulfur
2 mol/mol S
Dissolved in
product
1 lb/bbl feed
H2S
Sulfur in Feed
C3-
1.0+0.09*(YLN)
IC4
0.377*(YLN)
Calculate
Pure
NC4
0.186*(YLN)
Calculate
Pure
C5 to 180°F
Fig. 7.3 (YLN)
Calculate
Calculate
131°F
Fig. 7.5
180 to 400°F
Fig. 7.4
Calculate
Calculate
281°F
Fig. 7.5
∆
Calculate
460°F
Fig. 7.5
400 to 520°F
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Trends
• Figure 7.3
 The lighter the feedstock the more
readily it cracks
 The curves for the 10.9 Watson K factor
feed are 10% lower than the curves for
the 12.1 Watson K factor feed.
• Suggests the calculation procedure:

 K − 12.1  
=
Y YKW =12.1 1 − 0.1  W

 10.9 − 12.1  

Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Trends
• Figure 7.4
 Start over-cracking the heavy naphtha
fraction when the light naphtha yields
gets above 25 vol%.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield – Makeup Hydrogen
• Make up hydrogen must be added to compensate for that chemically consumed
& any dissolved in the liquid products
 Primary hydrogen consumed will be to saturate aromatics & olefin structures and break
C-C bonds
 Additional hydrogen needed for the removal of sulfur
• Breaking of the C-S-C and C-SH bonds
• Assume the more conservative 2 mol H2 per mol S
 Liquid products leave with dissolved H2
• Text book recommends 1 lb H2 per bbl liquid product
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
4
Hydrocracker Yield Example
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Estimate the Watson K factors
for the liquid products
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Calculate other values based on
the physical property
information & flow data.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine amount H2S
produced & amount of H2
required to remove
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine Vol% Light Naphtha
Yield (based on 12.1 Watson K
factor feed).
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Correct to actual Watson K
factor of feed. Calculate
associated mass values.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine Vol% Heavy Naphtha
(180 to 400oF) Yield. Calculate
associated mass values.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine Vol% Butane Yield.
Calculate associated mass
values.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine Wt% C3- Yield. Split
between C1, C2, & C3.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine mass amount of
Distillate (400 to 520°F) based
on total mass balance.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine all other yield
amounts.
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Determine the amount of
dissolved H2 in the liquid
products (C3 & heavier)
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)
Hydrocracker Yield Example
Updated: January 26, 2016
Copyright © 2016 John Jechura (jjechura@mines.edu)