visbreaking unit simulation model for the prediction of ......for kbc 2005 method, simulation model...

1

Visbreaking Unit Simulation Model for the Prediction of Process Performance and Visbreaker Residue Stability

Sara Sousaa, Filipa Ribeiroa, Ana Rita Costab

a Departamento de Engenharia Química, Técnico Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal b Galp, Rua Tomás da Fonseca - Torre C, 1600-209 Lisboa, Portugal

Sulfur content in bunker fuels has been reduced in order to decrease emissions of sulfur oxides into the atmosphere. In January 2020, the sulfur content in bunker fuels will be limited to 0.5%wt. The production of this fuel requires processing sweet crudes in Galp refineries. This is a challenging situation because these crudes have a higher tendency to instability.

In this work, a rigorous simulation model of the visbreaking unit was developed, using the Petro- -Sim™ software, which allows a good prediction of yields, product properties, including visbreaker residue stability. This is the main component of fuel.

The simulation model was solved through two methods for maximum visbreaker conversion calculation, KBC 1985 and KBC 2005. KBC method 1985 presents a good prediction of visbreaker residue stability. For KBC 2005 method, simulation model predictions are more dependent on feedstock quality and more representative of reality.

A delta-base vector structure was created and allows the implementation of the data generated by the simulation model in Galp linear programming model. This structure was validated using a linear representation model. The implementation in the linear programming model of the visbreaker unit simulation model will allow an efficient and optimized selection of crudes that will maximize the refining margin, ensuring the production of low sulfur fuel oil.

KEYWORDS: Visbreaker, Petro-Sim™, Delta-Base Vectors, Thermal Cracking, Visbreaker Residue

Stability, Refining

1 Introduction

Fuel oil, used as a bunker fuel, causes large emissions of SOx (Sulfur Oxides) into the atmosphere, which are harmful to human health and to the environment.

IMO (International Maritime Organization), a specialized agency of the United Nations, is the global standard-setting authority for the safety, security and environmental performance of international shipping. In order to reduce SOx emissions from ships, the sulfur content limit in fuel oil has been progressively reduced. As from January 2020, there will be a substantial cut in the sulfur content limit, from 3.5%wt (High Sulfur Fuel Oil – HSFO) to 0.5%wt (Very Low Sulfur Fuel Oil – VLSFO) [1].

In order to meet the new IMO regulations, ships can limit the air pollutants installing exhaust gas cleaning systems, also known as scrubbers.

The alternative that should be adopted by Galp to supply the VLSFO market consists in mixing residues produced from sweet crudes (sulfur content below 1%wt) with other components with very low sulfur content (cutter stocks). The production of VLSFO is a major challenge due to the fuel high tendency for instability as well as sediments and coke generation.

Fuel oil produced in Galp refineries can be composed by atmospheric, vacuum and visbreaker residues. The visbreaker residue (RVB) is the most commonly used in the production of fuel oil, since its use brings an economic advantage.

1.1 Objectives This work addresses the development of a

simulation model of Sines visbreaking unit in Petro-Sim™ software. This model will predict unit performance and RVB stability depending on the type of the unit feedstock. This model will be implemented in Galp linear programming (LP) model in order to select the crudes that maximize refining margin ensuring the production of VLSFO.

2 Visbreaking Unit

2.1 Process Description The refining process starts by feeding the

crude oil, or usually a mixture of crudes (crude mix), into an atmospheric distillation unit. Here crude are separated into several fractions (defined by cut point – the temperature on the whole crude TBP (true boiling point) curve that represents the upper and lower limits [2]).

In Sines refinery, atmospheric distillation has a top gas stream, a naphtha stream, a kerosene

https://goo.gl/maps/qsq7swg8HCM2

2

stream, two streams of gasoil (light gasoil and heavy gasoil) and a bottom stream – atmospheric residue (RAT). The RAT yield depends considerably on the crude mix fed to the atmospheric distillation unit. The heavier the crude oil mixture fed, the higher the RAT yield.

RAT is then fed to a vacuum distillation unit, where is produced a vacuum distillate stream, a vacuum gas oil (VGO) and a vacuum residue (RV) stream. RV has high viscosity, which decreases its commercial value. Therefore, RV is fed to a visbreaking unit.

The main purpose of visbreaking unit (VB) is to convert heavy, high viscosity feedstocks, like RV, to lower viscosity products suitable for use in fuel oil. This reduction is obtained by decomposing heavy molecules into lighter molecules through thermal cracking reactions. Since VB operates at low conversions (low extensions of thermal cracking reactions), its main product is visbreaker residue (RVB), with a yield of about 80-90%wt. Another benefit from the visbreaking operation is the production of gas, naphta and gas oil (GOVB) streams that usually have higher product values than RVB [3].

Sines refinery has a soaker visbreaker, where the bulk of the cracking reactions occurs not in the furnace but in a soaker drum downstream the furnace. In the soaker drum the heated feedstock is held at high temperature for a predetermined period of time allowing cracking to occur. Then soaker effluent goes to a fractionator column where RVB is separated from lighter fractions [3].

2.2 Process Reactions Thermal cracking is the decomposition of

hydrocarbons at elevated temperatures, resulting in the formation of lower molecular weight products and is a first-order reaction [4].

𝑣 = 𝑘 ∙ 𝑐 ( 1 )

− ln (𝑎

𝑎 − 𝑥) = 𝑘 ∙ 𝑡 ( 2 )

During thermal cracking, the saturated

(paraffinic) compounds are transformed into saturated compounds of lower molecular weight. In high severity conditions (high temperature) polymerization reactions are favored leading to resins and asphaltenes cracking and to coke formation.

2.3 Operating Conditions The extent of cracking reactions, i.e. GOVB

conversion, and RV visbreaking are controlled by the severity of the unit. The visbreaker

severity depends on the operating temperature and residence time.

Variations in feedstock quality will have impact in the conversion level obtained at a given severity [5]. Thus, the visbrekaer operations severity is generally limited by the visbroken product stability.

3 RVB Stability

A fuel is stable if there is no asphaltenes flocculation. On the other hand, instability may be irreversible, i.e. precipitated asphaltenes may not be re-dissolved [6]. To ensure fuel oil stability it is necessary that RVB is also stable. Generally, cutter stocks are paraffinic (gasoil and kerosene) and, therefore, RVB stability degree must be high enough to prevent asphaltene flocculation during blending with cutter stocks. RVB stability is controlled by performing a peptizing-value (p-value) test [7].

The p-value provides the peptization state of the asphaltenes in residues. A residue is then considered stable for a p-value greater than 1.2. The p-value is obtained by adding cetane (paraffinic compound, once paraffins flocculate the asphaltenes) to the sample under study until the asphaltenes begin to flocculate. This property is determined by equation (1), where Xmin is the critical dilution in cetane, i.e. the amount of cetane (ml) that can dilute 1g of the sample until asphaltenes flocculation begin. This method has a high repeatability, about 0.07 [7].

𝑉𝑎𝑙𝑜𝑟 − 𝑝 = 1 + 𝑋𝑚𝑖𝑛 ( 3 )

There are methods of evaluating the stability of fuel using other solvents. However, the p-value is a widely used stability indicator and is also used in Galp refineries.

3.1 Asphaltenes Asphaltenes are defined as the insoluble

fraction in n-heptane and soluble in toluene and represent the heavier and more complex fraction of crude oil [8] [9]. Asphaltenes are high polarity compounds composed by a very condensed aromatic and naphthenic structure. Asphaltenes present short paraffinic side chains and also heteroatoms, such as sulfur, nitrogen, oxygen and metals. The large number of aromatic rings gives to asphaltenes a flat structure [10].

3

4 Visbreaker Unit Simulation Model

In this work it was developed a rigorous simulation model of the VB unit in Petro-Sim ™ software, version 7.0.

The visbreaker simulation model currently used by Galp is a simple planning model that calculates yields and product properties according to the average reality of the unit's operating cycle. This model does not predict the RVB stability produced.

For the VB unit simulation model, Petro-Sim ™ has VIS-SIM ™ technology that simulates the thermal cracking, based on reaction kinetics.

4.1 Maximum Visbreaker Conversion Maximum Visbreaker Conversion (MVC), is

a feedstock characterization parameter and depends on the asphaltene content and the nature of the feedstock (aromatic or paraffinic). The MVC is defined as the conversion at which a visbroken residue is produced at the stability limit (ABN = 46, p-value = 1.15). Conversions above the MVC value do not guarantee a stable RVB. Petro-Sim™ allows the calculation of this property using two methods: KBC method 1985 (KBC 1985) and KBC method 2005 (KBC 2005).

By the KBC 1985 method the Petro-Sim™ model calculates the MVC taking into account RV asphaltenes content and unit feed BMCI (Bureau of Mines Correlation Index – fuel aromaticity indicator [11]).

KBC 2005 is a more accurate method that takes into account RV asphaltenes and wax contents.

4.2 Severity Petro-Sim™ calculates severity using the

equation ( 4 ).

𝑆𝑒𝑣𝑒𝑟𝑖𝑡𝑦 =𝐺𝑂𝑉𝐵 𝐶𝑜𝑛𝑣𝑒𝑟𝑠𝑖𝑜𝑛

𝑀𝑉𝐶 ( 4 )

The RVB stability is ensured if severity value is less than 100%.

4.3 P-Value Petro-Sim ™ calculates the p-value based

on the ABN (Aromatic Blending Number wich is a fuel aromaticity and stability indicator [12]) value. P-value is given through equation ( 5 ).

𝑉𝑎𝑙𝑜𝑟 − 𝑝 =𝐴𝐵𝑁

40 ( 5 )

4.4 Simulation Model Construction and Calibration

The construction of VB unit simulation model requires real unit design and operation data.

The objective of calibration is to ensure that model represents the real unit performance in terms of yields and product properties. In calibration the model automatically calculates a set of calibration factors to achieve the best match between the predicted properties values and the real properties values.

In order to ensure that the simulation model mimics reality, the data used for calibration should be representative of the visbreaking operation.

The data required for model calibration are real operating conditions, product yields and feed and products characterization in terms of density, viscosity, distillation curve, sulfur content, RVB p-value, wax and asphaltene content in the feed stream. These data are obtained through laboratory analyzes of samples collected directly from the unit running in a steady state.

The days selected were November 11, 2017 (calibration 11), March 1, 2018 (calibration 1), and March 8, 2018 (calibration 8). In calibration procedure it was used the three data sets corresponding to the three different operating days.

In order to choose the calibration that best represents the unit real performance, predictions of the three days were made using each one of the three calibrations.

5 Linear Programming Model

The LP model is a fundamental tool in planning refining activity. The LP model determines monthly the refineries production, the raw materials to be processed and the operating conditions of the process units that allow the optimization of the refining margin. The LP model is also used by Galp to carry out economic studies and to plan annual budgets. Galp’s LP model uses the software GRTPMS (Generalized Refining Transportation Marketing Planning System).

5.1 Delta-Base Structure The implementation of VB unit model

simulation data in the LP model is performed through a delta-base structure. The delta-base structure determines the impact that linear variations on feedstock properties have on a given product property or yield. Thus, linear variations (deltas) are applied to feedstock properties and operating conditions (vectors)

4

and the effect of these variations on the performance of the unit is observed.

It is required to do a sensitivity analysis in order to select the vectors, i.e. the feedstock properties and operation conditions, that affect the most the VB unit performance. In this analysis, deltas are defined to ensure that they represent linear impacts on products yields and properties.

A case, that corresponds to a feedstock and products yields and properties is then defined. This case has to be representative of the VB unit operation. Deltas are applied to each vector of this case, which produce a linear impact on the yields and properties of the products. The case chosen will serve as the basis for the implementation of the delta base structure.

The impacts that deltas caused in each vector on the properties and yields of the products of the process unit are generated in the simulation model in Petro-Sim™ using the Linear Programming Utility (LPU) tool and are exported to a delta-base template file which will be provided to LP.

5.2 MRL Predictions In order to evaluate the delta-base, that will

be implemented in LP, model a linear representation model (MRL) is developed in Excel using the data generated by LPU.

6 Results

6.1 KBC 1985 Method

6.1.1 Calibration Results Figure 1 to Figure 7 compare the real yields

and properties with predicted results for each model calibration corresponding to the three different days (November 11, March 1 and 8).

Figure 1 – Prediction of visbreaker residue yield with each of the three calibrations using the

maximum visbreaker conversion calculation method KBC 1985.

Figure 2 – Prediction of visbreaker gasoil yield

with each of the three calibrations using the maximum visbreaker conversion calculation method

KBC 1985.

Figure 3 – Prediction of visbreaker residue

specific gravity with each of the three calibrations using the maximum visbreaker conversion

calculation method KBC 1985.

Figure 4 – Prediction of visbreaker gasoil

specific gravity with each of the three calibrations using the maximum visbreaker conversion



viscosity 100 with each of the three calibrations using the maximum visbreaker conversion


80

85

90

95

11-11-2018 01-03-2018 08-03-2018RV

B Y

ield

(%

wt)

Calib11 Calib1 Calib8 Real

4

6

8

10

12

11-11-2018 01-03-2018 08-03-2018GO

VB

Yie

ld (

%w

t)


0.96

0.98

1.00

1.02

1.04

11-11-2018 01-03-2018 08-03-2018R

VB

Sp

ecif

ic G

ravi

ty

(g/c

m3)


0.810

0.820

0.830

0.840

0.850

11-11-2018 01-03-2018 08-03-2018

GO

VB

Sp

ecif

ic

Gra

vity

(g/

cm3)


0

100

200

300

400

11-11-2018 01-03-2018 08-03-2018

RV

B V

isco

sity

100

oC

(cSt

)


5


p-value with each of the three calibrations using the

maximum visbreaker conversion calculation method KBC 1985.

Figure 7 – Prediction of isoconversion with each of the three calibrations using the maximum visbreaker conversion calculation method KBC

1985.

As can be seen from the results presented

above, calibration 8 presents prediction values with the greatest deviation from reality.

Calibrations 1 and 11 present good predictions with similar deviations, comparatively to the reality. However, on 11-11-2017 is processed a crude mix with Isthmus crude oil, which has a high asphaltenes content. Therefore, in order to produce a stable RVB, the VB unit has to operate with a severity lower than usual. As this is a less typical situation, the calibration factors selected correspond to calibration 1 since in this day it was processed a more common crude mix.

6.1.2 Crude Mix Predictions In order to validate the model, it is important

to check model performance, not only from real RV characterized in the lab, but also when processing VB unit feed obtained through simulation of the crude mix. These feedstocks are obtained simulating RAT and RV streams from crude assays fed to simulation models. The LP model works this way.

Figure 8 to Figure 14 present the real and predicted yields and product properties. All figures show the prediction using the actual

model and the rigorous simulation model developed in this work.

Figure 8 – Prediction of visbreaker residue yield

for different days of operation with the actual model and with the new model using the maximum

visbreaker conversion calculation method KBC 1985.


for different days of operation with the actual model and with the new model using the maximum



specific gravity for different days of operation with the actual model and with the new model using the maximum visbreaker conversion calculation method

KBC 1985.

1.0

1.2

1.4

1.6

1.8

11-11-2018 01-03-2018 08-03-2018

RV

B P

-Val

ue


0

10

20

30

11-11-2018 01-03-2018 08-03-2018

Iso

con

vers

ion

(%

wt)


82

84

86

88

90

92

RV

B Y

ield

(%

wt)

Actual Prediction Real

6

8

10

12G

OV

B Y

ield

(%

wt)


0.991.001.011.021.031.041.05

RV

B S

pec

ific

Gra

vity

(g

/cm

3)


6


specific gravity for different days of operation with the actual model and with the new model using the maximum visbreaker conversion calculation method

KBC 1985.


viscosity 100C for different days of operation with the actual model and with the new model using the maximum visbreaker conversion calculation method

KBC 1985.

Figure 13 – Prediction of visbreaker residue p-

value for different days of operation with the actual model and with the new model using the maximum


Figure 14 – Prediction of isoconversion for

different days of operation with the actual model and with the new model using the maximum


By analyzing the predictions from the crude mix it is possible to verify that the new simulation model built presents much more rigorous predictions than the current model, mainly for the yields and isoconversion, i.e. the new simulation model is sensitive to the feedstock load to the unit. The new model is also able to predict the stability of RVB, which is crucial for the production of VLSFO.

6.1.3 MRL predictions The implementation of Petro-Sim™

simulation model in LP model was validated using MRL.

Figure 15 to Figure 20 compare the MRL predictions with the simulation model predictions in Petro-Sim™. The figures present yields and product properties predictions and real values.


yield by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker

conversion calculation method KBC 1985.

0.81

0.82

0.83

0.84

0.85G

OV

B S

pec

ific

Gra

vity

(g

/cm

3)


0

200

400

600

RV

B V

isco

sity

100

oC

(c

St)


0.9

1.1

1.3

1.5

1.7

RV

B P

-Val

ue


15

17

19

21

23

25

Iso

con

vers

ion

(%

wt)


82

84

86

88

90

92

RV

B Y

ield

(%

wt)

PS Prediction MRL Real

7


by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker



specific gravity by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker conversion calculation method KBC

1985.



1985.


p-value by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker



viscosity 100C by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker conversion calculation method KBC

1985.

The developed MRL allows to obtain results

very similar to those obtained in the simulation model built in Petro-Sim™. As can be seen above, the predictions by the MRL and the Petro-Sim™ model are practically coincident. These results validate the vectors, bases and deltas chosen.

6.2 KBC 2005 Method According to KBC, the most recent method,

KBC 2005, is more accurate than KBC 1985 method. In order to evaluate if the KBC 2005 method leads to RVB stability with greater adherence to reality, a model was solved using this method.

6.2.1 Real Data Predictions Figure 21 compares the real RVB p-value

with RVB p-value predicted using KBC methods 1985 and 2005.

6

8

10

12

GO

VB

Yie

ld (

%w

t)


0.98

1.00

1.02

1.04

1.06

RV

B S

pec

ific

Gra

vity

(g

/cm

3)


0.82

0.83

0.84

0.85

GO

VB

Sp

ecif

ic G

ravi

ty

(g/c

m3)


0.9

1.1

1.3

1.5

1.7

RV

B P

-Val

ue


0100200300400500600

RV

B V

isco

sity

100

oC

(cS

t)


8


p-value using laboratory analysis data as input using the two maximum visbreaker conversion

calculation methods KBC 1985 and 2005.

This figure shows that predictions using KBC

2005 method present lower deviations from real values than predictions using KBC 1985 method. This shows that using KBC 2005 method the predictions are more accurate.

In what concerns to yields and other product properties the VB unit simulation model results with the two methods are very similar.

6.2.2 Crude Mix Predictions In order to verify the performance of the

model using the calculation method KBC 2005, predictions were made from the crude mix, using crude assays, as it was done for the model with the KBC 1985 method.

Figure 22 present the real and predicted yields and product properties. The figure shows the prediction using KBC 1985 and 2005 methods.


p-value from crude mix using the two maximum visbreaker conversion calculation methods KBC

1985 and 2005.

Like it was observed with real data

predictions, the crude mix predictions using the two MVC calculation methods are very similar too with respect to yields and properties.

Regarding the RVB p-value, the model solved using the KBC 2005 method, shows predictions with a greater amplitude of values that better mimic the real values trend. These predictions show a slight improvement compared to the predictions made with the KBC 1985 method.

6.2.3 MRL Predictions The implementation of the simulation model

using KBC 2005 method in LP model was studied using an MRL.

Figure 23 to Figure 28 compare the MRL predictions with the simulation model predictions in Petro-Sim™, when using KBC 2005 method. The figures present yields and product properties predictions and real values.


yield by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker



by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker

conversion calculation method KBC 2005..

0.8

1.0

1.2

1.4

1.6

1.8

11-11-2017 01-03-2018 08-03-2018

RV

B P

-Val

ue

KBC 2005 Prediction KBC 1985 Prediction Real

1.01.11.21.31.41.51.6

RV

B P

-Val

ue

KBC 2005 KBC 1985 Real

82

84

86

88

90

92

RV

B Y

ield

(%

wt)

PS KBC 2005 MRL KBC 2005

Real

6789

101112

GO

VB

Yie

ld (

%w

t)


Real

9



2005.



2005.

Figure 27 – Prediction of visbreaker residue p-

value by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker



viscosity 100C by Petro-Sim™ model and MRL for different days of operation using the maximum visbreaker conversion calculation method KBC

2005.

With the simulation model built with the KBC

2005 calculation method, the MRL developed can mimic the behavior of the model in Petro- -Sim™ when predicting the actual performance of the VB unit.

Therefore it is possible to state that the delta- -base structure developed using the KBC 2005 method would present good results when implemented in the LP model, achieving a good optimization in the crudes selection for the production of VLSFO.

7 Conclusions

The simulation model of the VB unit with the KBC method 1985 presents a very good prediction of the reality with respect to yields and product properties. The predicted performance is highly dependent on the feedstock quality. Regarding the RVB stability the p-value predictions present a good adherence to the real values meaning that the new simulation model is able to predict RVB stability which is crucial for VLSFO production. It should be noted that the stability prediction is not ensured by the simulation model that Galp currently use. The new simulation model corresponds to a great improvement in the Galp simulation models as a whole.

The simulation model predictions using KBC 2005 method are very similar to those obtained by the simulation model using the KBC method 1985. The MVC values obtained by the simulation model when using the KBC 2005 method are in a wider range than the values obtained by the KBC method 1985. This is also observed in p-value predictions of the simulation model with the KBC 2005 method. In

0.960.981.001.021.041.061.08

RV

B S

pec

ific

Gra

vity

(g/

cm3)


Real

0.820

0.830

0.840

0.850

GO

VB

Sp

ecif

ic G

ravi

ty (

g/cm

3)


Real

0.9

1.1

1.3

1.5

1.7

RV

B P

-Val

ue


Real

0

200

400

600

800

1000

RV

B V

isco

sity

100

oC

(cS

t)


Real

10

contrast to KBC 1985, the p-value predictions with the KBC 2005 method are more dependent on the feedstock quality. This method presents an improvement in the p-value prediction comparatively to the old method.

In this work it was carried out the development of a delta-base structure, in order to provide the simulation data to the LP model. The representation of the delta-base structure in the VB unit is pioneering in Galp.

To generate the delta-base representation, was used the Linear Programming Utility of the Petro-Sim™ software to obtain the impacts that variations in the feedstock properties have on given products properties. This is the information required to implement the simulation model in the LP model.

The delta-base structure was validated using the linear representation model that allows the evaluation of the new VB unit representation in the Galp LP model. Both linear representation models, constructed from the simulation model with the KBC1985 method and with KBC 2005, are robust and reproduce with very low deviations the simulation model predictions.

The delta-base structure constructed for the implementation of the simulation model in the LP model is validated and is representative of reality, being sufficiently robust to be implemented in the LP model. This allows to perform good optimizations in the selection of crudes for the production of VLSFO.

The simulation model of the VB unit with the KBC 2005 method makes good predictions of yields and product properties and its delta-base representation will be implemented in the PL model.

References

[1] IMO, "Sulphur 2020 – cutting sulphur

oxide emissions," [Online]. Available: http://www.imo.org. [Accessed Fev 2019].

[2] D. S. J. Jones and P. P. Pujadó, Handbook of Petroleum Processing, Springer, 2006.

[3] J. G. Speight, Handbook of Petroleum Refining, CRC Press, 2017.

[4] J. Singh, S. Kumar and M. O. Garg, "Kinetic Modelling of Thermal Cracking of Petroleum Residues: A Critique," Fuel Processing Technology, vol. 94, pp. 131-144, 2012.

[5] Encyclopaedia of Hydrocarbons, vol. II/Refining and Petrochemicals, Istituto della Enciclopedia Italiana, 2005.

[6] A. Breneol, "Marine Fuel Stability and Compatibility - Issues, Tests and Management".

[7] Shell Global Solutions International B.V., "SMS 1600-01 - Determination of State of Peptization of Asphaltenes in Heavy Oil Streams," 2001.

[8] E. Y. Sheu and D. A. Storm, Asphaltenes - Fundamentals ans Applications, New York: Plenum Press, 1995.

[9] A. Pina, P. Mougin and E. Behar, "Characterisation of Asphaltenes and Modelling of Flocculation – State of the Art," Oil & Gas Science and Technology – Rev. IFP, vol. 61, no. 3, pp. 319-343, 2006.

[10] H. Groenzin and O. C. Mullins, "Molecular Size and Structure of Asphaltenes," Petroleum Science nd Technology, vol. 19, no. 1-2, pp. 219-230, 2001.

[11] J. H. Gary, G. E. Handwerk and M. J. Kaiser, Petroleum Refining - Technology and Economics, CRC Press, 2007.

[12] KBC Andvanced Technologies Ltd, Petro-Sim Help.

1 Introduction1.1 Objectives

2 Visbreaking Unit2.1 Process Description2.2 Process Reactions2.3 Operating Conditions

3 RVB Stability3.1 Asphaltenes

4 Visbreaker Unit Simulation Model4.1 Maximum Visbreaker Conversion4.2 Severity4.3 P-Value4.4 Simulation Model Construction and Calibration

5 Linear Programming Model5.1 Delta-Base Structure5.2 MRL Predictions

6 Results6.1 KBC 1985 Method6.1.1 Calibration Results6.1.2 Crude Mix Predictions6.1.3 MRL predictions

6.2 KBC 2005 Method6.2.1 Real Data Predictions6.2.2 Crude Mix Predictions6.2.3 MRL Predictions

7 Conclusions

visbreaking unit simulation model for the prediction of ......for kbc 2005 method, simulation model...

Documents