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Frontiers of Engineering Management

Front. Eng    2018, Vol. 5 Issue (2) : 195-201     https://doi.org/10.15302/J-FEM-2017052
RESEARCH ARTICLE |
Impact of crude distillation unit model accuracy on refinery production planning
Gang FU, Pedro A. Castillo CASTILLO, Vladimir MAHALEC()
Department of Chemical Engineering, McMaster University, ON L8S 4A7, Canada
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Abstract

In this work, we examine the impact of crude distillation unit (CDU) model errors on the results of refinery-wide optimization for production planning or feedstock selection. We compare the swing cut+ bias CDU model with a recently developed hybrid CDU model (Fu et al., 2016). The hybrid CDU model computes material and energy balances, as well as product true boiling point (TBP) curves and bulk properties (e.g., sulfur % and cetane index, and other properties). Product TBP curves are predicted with an average error of 0.5% against rigorous simulation curves. Case studies of optimal operation computed using a planning model that is based on the swing cut+ bias CDU model and using a planning model that incorporates the hybrid CDU model are presented. Our results show that significant economic benefits can be obtained using accurate CDU models in refinery production planning.

Keywords impact of model accuracy on production planning      swing cut+ bias CDU model      hybrid CDU model      refinery feedstock selection optimization      optimization of refinery operation     
Corresponding Authors: Vladimir MAHALEC   
Just Accepted Date: 25 August 2017   Online First Date: 30 October 2017    Issue Date: 28 June 2018
 Cite this article:   
Gang FU,Pedro A. Castillo CASTILLO,Vladimir MAHALEC. Impact of crude distillation unit model accuracy on refinery production planning[J]. Front. Eng, 2018, 5(2): 195-201.
 URL:  
http://journal.hep.com.cn/fem/EN/10.15302/J-FEM-2017052
http://journal.hep.com.cn/fem/EN/Y2018/V5/I2/195
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Gang FU
Pedro A. Castillo CASTILLO
Vladimir MAHALEC
Fig.1  Actual yield vs. yield from equidistance assumption
Fig.2  Sample CDU
Fig.3  Predicting the kerosene TBP curve
TBP Unit Crude oil 1 Crude oil 2
1 F -32.0 -17.5
5 F 96.9 94.9
10 F 196.0 183.4
30 F 402.8 413.4
50 F 567.0 626.9
70 F 771.8 865.9
90 F 1143.2 1232.7
95 F 1331.7 1396.4
99 F 1531.9 1545.6
API 34.2 32.0
Sulfur wt% 2.4 2.3
Tab.1  Properties of crude oil 1 and crude oil 2
Op. mode HNaphtha 95 Kero 95 Diesel 95 Kero 05 Diesel 05 AGO 05
F F F F F F
Base case 360 520 640 350 460 540
Max HNaphtha 380 520 640 360 460 540
Max kerosene 340 540 640 330 470 540
Max Diesel 360 520 660 350 460 560
Tab.2  Product TBP specifications for different operating modes
CDU feed Op. mode HNaphtha Kerosene Diesel AGO
/% /% /% /%
Crude oil 1 Base case 6.08 13.55 8.50 17.62
Max HNaphtha 6.96 12.68 8.49 17.62
Max kerosene 4.74 16.06 7.31 17.64
Max Diesel 6.08 13.39 10.64 15.64
Crude oil 2 Base case 4.74 10.06 7.65 12.86
Max HNaphtha 5.64 9.19 7.63 12.86
Max kerosene 3.68 12.05 6.70 12.88
Max Diesel 4.74 9.89 9.74 10.93
Tab.3  Product yields (% of CDU feed) based on equidistance assumption
CDU feed HN Naphtha/Kero Kero Kero/Diesel Diesel D-A AGO
Crude oil 1 4.74 2.23 12.68 1.15 7.31 2.18 15.46
Crude oil 2 3.68 1.95 9.19 0.92 6.70 2.12 10.75
Tab.4  Swing cut sizes (% of CDU feed) using the volumetric transfer ratio method
CDU feed Op. mode HNaphtha/% Kerosene/% Diesel/% AGO/%
Crude oil 1 Base case 5.62 16.95 10.72 12.47
Max HNaphtha 6.71 15.74 10.86 12.45
Max Kerosene 4.32 20.80 7.61 13.02
Max Diesel 5.62 16.83 13.12 10.18
Crude oil 2 Base case 4.35 12.76 9.51 8.69
Max HNaphtha 5.30 11.70 9.64 8.67
Max Kerosene 3.25 15.92 7.02 9.12
Max Diesel 4.35 12.65 11.60 6.71
Tab.5  Product yields (% of CDU feed) from rigorous simulation
CDU feed Op. mode Heavy naphtha Kerosene Diesel AGO
Crude oil 1 Base case -0.46 3.40 2.21 -5.15
Max HNaphtha -0.25 3.06 2.37 -5.17
Max Kerosene -0.42 4.74 0.30 -4.62
Max Diesel -0.46 3.44 2.48 -5.46
Average -0.40 3.66 1.84 -5.10
Crude oil 2 Basic -0.39 2.71 1.86 -4.17
Max HNaphtha -0.33 2.51 2.02 -4.19
Max Kerosene -0.43 3.87 0.32 -3.76
Max Diesel -0.39 2.75 1.86 -4.22
Average -0.39 2.96 1.51 -4.09
Tab.6  Yield biases (% of CDU feed): swing cut vs. rigorous model
Fig.4  Sample refinery flowchart
Mix #1 Mix #2 Mix #3
Crude oil 1 0.2 0.2 0.5 0.5 0.8 0.8
Crude oil 2 0.8 0.8 0.5 0.5 0.2 0.2
CDU model Swing cut+ bias Hybrid Swing cut+ bias Hybrid Swing cut+ bias Hybrid
Regular gasoline 42 42 42 42 42 42
Premium gasoline 48 48 48 48 48 48
Kerosene 25 25 25 25 25 25
Diesel 0 0 0 0 0 0 0
Diesel 1 14 14 14 14 14 14
Cost, 103 $/day 8032.1 7237.1 7224.7 7475.7 6411.2 7711.6
Tab.7  Total cost using different CDU models
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