2. Reactor Models in Romeo
Abhay Sawant
Technical Support
October 2012

3. Agenda
Refinery Overview
Refinery Reactors Overview
Demonstration

4. Typical Refinery Overview
Romeo Reactor Model Portfolio
8 reactor models covering the entire refinery
ROMeo 5.3: HF and Sulfuric acid alkylation and FCC
ROMeo 5.3.1: Reformer
ROMeo 6.0: Delayed coker, Visbreaker, Isomerization
ROMeo 6.0.2: Hydrotreating/hydrocracking, same reactor model can be configured as hytrotreater or hydrocracker by changing catalyst type 4 4

5. Refinery Reactors Crack heavier gasoil to lighter more useful products
Fluidized Catalytic Cracker (FCC)
Hydrocracker
Delayed Coker
Visbreaker
Upgrade gasoline quality
Reformer: Convert straight run naphtha to high octane product
Alkylation: Add Isobutane to low molecular weight C5- alkenes
Hydrofluoric Acid and Sulfuric acid Alkylation models
Isomerization: Convert n-paraffins to iso-paraffins to increase octane values
Remove impurities from reactor feeds and products
Hydrotreater: Remove sulfur from petroleum products to reduce emissions
© Invensys

6. Reactor Models License Agreement between ExxonMobil and Invensys
Since 2004, ExxonMobil has used Invensys ROMeo™ software in multiple applications
ExxonMobil Research and Engineering Company (EMRE) and Invensys have entered into a licensing agreement that will allow Invensys to license EMRE process models to 3rd parties
ExxonMobil uses versions of these models in its business for optimization, process engineering, design, and operations monitoring
Invensys has full access to the code and will provide all support and maintenance services to its customers
Invensys is the exclusive supplier of EMRE technology

7. Refinery Reactors Overview
FCC
Can model any FCC unit with up to 20% vacuum bottom resid
Integrated in 5.3
Feed synthesis will be in 6.0.2
Reformer
Can model Semi-Regen, Cyclic, or CCR.
Integrated in 5.3.1
C8 Aromatics splitter and coke model will be in 6.0.2
Validated by GS Caltex and Thai Oil
HDP
Can model hydrotreating and hydrocracking of any feed type with a single reactor
Both reactor model and feed synthesis will be ROMeo 6.0.2
HF Alky
Can model both UOP and Phillips HF alkylation processes
Validated and implemented by ExxonMobil in RTO project
SF Alky
Can model both DuPont Stratco (Effluent refrigeration ) and ExxonMobil Auto refrigeration sulfuric acid alkylation processes
ISOM
Model light naphtha isomerization processes
Integrated in 6.0
DCU
Model delayed coker unit including coke drums and fractionator
VOM
Model visbreaking unit including furnace, fractionator and blending
ROMeo Refinery Reactor Model Portfolio
Most Comprehensive list of Refinery Reactor Models based on ExxonMobil operating experience

8. Key Features
Full suite of reactor modeling technology available for Refinery-wide Optimization
Based on years of operating experience by ExxonMobil
Rigorous kinetics based models allows accurate modeling over wider operating range
User-friendly GUI for tuning
Sim4ME Portal provides simple and user friendly Excel interface for offline simulation and what-if case studies 8 8

9. Benefits
ROMeo Open equation based modeling enables robust, broader scope modeling and optimization of a refinery
Offline simulation and engineering study capabilities
Planning with LP vector update from the reactor models
Performance monitoring of the reactor and catalyst

10. Reformer Reactor Purpose: Reform naphtha to increase octane value
Feedstock: Straight-run heavy naphtha from crude tower
Reactions:
Isomerization of normal paraffins to isoparafins
Dehydrogenation of naphthenes and dehydrocyclization of paraffins to aromatics
Some hydrocracking side reactions
Process:
Semi-regeneration: All reactors running and regenerated at the same time
Cyclic: One reactor is regenerated at a time and switches online and offline
Continuous Catalytic: Continuous regeneration
Reformer is another important reactor. It converts the low octane heavy naphtha (C6+) from crude tower to high octane gasoline .
In a reformer the straight chain paraffins become branched iso-paraffins through isomerization, or become naphthenes through dehydrocyclization. Naphthenes become aromatics, through dehydrogenation. Some side hydrocracking reactions also take place and produce coke which deposit onto the surface of the catalyst, causing degradation of activity. So the catalyst should be regenerated periodically. The catalytic reforming process can be catagorized into three different processes according to the way regeneration is conducted, Semi-regeneration, cyclic and continuous catalytic reforming (CCR). Semi-regen, all the reactors are running at the same time and all the reactors will be taken down for regeneration at the same time, For Cyclic process, there is a reactor offline for regeneration and other reactors are online. When the reactor regeneration completed, it will be back online, another reactor will be turned offline for regeneration. Unlike semi-regen, there will be no whole unit shut down due to reactor regeneration. The unit operation is is not interrupted by reactor regeneration. For a CCR, the reactors are stacked togethere and the reactor beds are no longer fixed. The regenerated catalyst comes in from the top of the first reactor and flows downward and exits at the bottom of the last reactor. Then the catalyt goes to the regeneration process and regenerated catalyst comes back to the top of the first reactor. Compared to cyclic process, the coke levels are maintained fairly constant, and there is no upset to the process due to reactor switch. The process mains at constant stable condition.
Reforming reactions are endothermic.

11. Reformer Reactor Model
Can model Semi-regen, Cyclic and CCR by changing catalyst types
Very flexible configuration, can be configured to have 1 or more reactors (beds), to include pre-heater, intermediate heaters and product flash
Product RON & MON (with the octane model), total aromatics, total C5+ Yield predicted
ExxonMobil has 10+ successful implementations. Invensys has validated the model with 2 sites and 3 units

12. FCC Reactor
Purpose: Crack heavy gas oil to produce lighter more valuable products
Feedstock: Mainly heavy gasoil from crude and vacuum towers
Products:
Light gases: Fuel gas LPG: To Alkylation Gasoline: Fuel
LCO: Fuel oil or diesel HCO: Fuel oil Slurry/Decant oil: Fuel
Different designs available from ExxonMobil, Shell, Shaw Stone Webster, CBI Lummus, UOP, and Kellogg
Reactor: Riser, Reactor, and Regenerator form a closed circuit
Catalyst: Circulated and regenerated in the circuit
FCC reactor is one of the most important reactors in a refinery, espeically for the refinery with gasoline as its major product. FCC contributes about 30% of a refinery’s gasoline pool. The LPG product can be further alkylated to formulate high octane gasoline too.
FCC from its first commercialization in the 1940s, has evolved greatly. The activity of the catalyst has been improved greatly. Now most of the cracking reactions have moved from the reactor vessel to the riser. Now the reactor vessel has little reactions, it is mainly a separation vessel now.
Although there are 6 different vendors/licensors the basic structure of the FCC reactor is very similar. It is composed of riser, reactor and regenerator, which constitute a closed circuit for the catalyst circulation.
FCC reactor model is the most complex reactor in the refinery due to its complex catalyst circulation and delicate pressure and energy balances. The catalyst circulates in the reactor like a fluid. Its circulation rate is determined by the pressure difference between the reactor vessel and regeneration vessel. A higher pressure difference causes a higher catalyst circulation rate, thus a higher catalyst to oil ratio. A higher cat/oil ratio increases the severity of the cracking reactions, and produces more coke. More coke means more energy is released in the regenerator and hotter regenerated catalyst. When the hotter regenerated catalyst mixes with the fresh feed, the mixture will have higher temperatures in the riser, causing more cracking. Thus the correct pressure balance must be maintained to yield optimal riser temperatures.

13. FCC Reactor Model Rigorous Kinetic Model
Energy and pressure balances rigorously modeled
Can model different designs, ExxonMobil has more than 20 successful implementations
More detailed than KBC FCC-SIM model
Feed synthesis/characterization included
The cracking reactions in the riser and the combustion reactions in the regenerator are kinetically modeled. The energy balance is maintained through thermo. The densities of dilute and dense phases of the reactor and regenerator are computed and pressures calculated.
The reactor model contains 4 subflowsheets: riser, reactor, regenerator and recycle. The riser subflowsheet contains the riser , divided into sections. It contains a minimum of 4 sections with different phases, single (vapor or liquid) or double. Reactor subsystem contains the dense phase disengage and stripping, the delumper and mapping from kinetic component slate to the fractionator slate. Regenerator subflowsheet contains the regenerator module for mass/enegery balance, the module that pass coke and catalyst property between regenerator and riser, and the modules for dilute and dense phases. Recycle subflowsheet is a mapping of component slate of the recycle stream from the fractionator slate to the kinetic slate used by the riser. Each subflowsheet has a manager, the manager passes information among subflowsheets. The FCC also has a overall manager.
The kinetic component slate used by the riser has 26 petro components and 14 real components for light ends (C4-). The fractionator component slate has 26 real components for light ends (C6-) and 67 petro component (C7+  NBP 632C).
The FCC reactor model can be configured to represent any of the 6 designs and different models for each design.
A separate Feed synthesis/characterization module is required to map the feed into the kinetic component slate.

14. Hydroprocessing (HDP) Reactor Model
Rigorous kinetic model of four major reaction types, coke effect can be modeled through reducing catalyst activity
Can model both hydrotreating and hydrocracking reactors by switching catalyst type
Has its own feed synthesis and analyzer (for sulfur and nitrogen prediction) to produce correct feed compositions from reference feed
ExxonMobil has more than 20 successful implementations

15. HF Alkylation (HFAlky) Reactor
Purpose: Convert light naphtha (C6- olefins) to high octane alkylate for gasoline blend
Feedstock: Light naphtha from FCC and Isobutane from hydrocracker
Reactions: Rapid exothermic reactions with HF as the catalyst
C3, C4, C5 olefins + iC4  Alkylate
Side reactions product high boiling point acid soluble oils (ASOs)
Technology from Phillips and UOP
Reactors: Water-cooled exchangers (UOP) and Differential Gravity Reactor (Phillips)
iC4 Recycle
iC4
C3=
C4=
C5=
Reactor
Acid Settler
Separation
Alkylate
HF Catalyst
LPG, nC4

16. HF Alkylation (HFAlky) Reactor Model
Can model both Phillips and UOP processes
Model includes both reactor and acid settler
Correlative model
Model predicts Isobutane conversion, alkylate, ASO rates, RON and MON
ExxonMobil has been implementing the reactor model with success
Key optimization variables
Optimize Isobutane recycle rate to maximize profit

17. Sulfuric Acid Alkylation (SFAlky) Reactor
Can model both DuPont Stratco (Effluent Refrigeration) and ExxonMobil Auto-Refrigeration processes
Both reactor and settler are modeled
Can be used to model entire reactor, or individual zones
Model predicts alkylate yields, RON, MON, acid consumption and spent acid composition
Key optimization variables
Optimize Isobutane recycle rate to maximize profit
Similar to the HFAlky model SFAlky is also a correlative model. The reactions are not affected by the pressure of the reactor. So both Dupont Stratco and Exxon Auto-Refrigeration process can be modeled. The pressure only determines the reactor temperature and vapor liquid equilibrium. For both processes, the vapor and liquid should have same pressure and temperature. So the model should be able to represent both processes.
The reactor model can be used to model a single reactor or zone, or lumps entire reactor into a single reactor module.
Unlike the HFAlky reactor model, the acid stream is modeled in the SFAlky model.
The alkylate is represented by 6 petro components. Unlike the HFAlky model, ASO modeled andrepresented by 9 components. A custom library is needed and is installed with ROMeo. But user has to put the SFAlky cumstor databank on the bank search list.???
The model assume no hydrocarbons other than ASOs are entrained in the acid.

18. Delayed Coker
Purpose: Thermal cracking of residual oil to gasoil and coke
Feedstock: residual oil from vacuum tower bottom
Products:
Offgas: Fuel gas LPG: To Alkylation Naphtha: feedstock to reformer
LCGO and HCGO: Feed to hydrotreating for diesel and other fuels
Coke: needle ,anode and fuel grades
Batch-continuous process for coke production (coke drum switch cycle), main distillation tower does not have steady state, swings with cycle
Delayed coker cracks the resid (residual oil) from bottom of vacuum tower into light ends, gasoil and coke. Coke is a intended product for the delayed coker, not like FCC, coke is undesirable and has to be burned off. A delayed coker

19. Delayed Coker Reactor (DCU)
Models the unit including coke drum and fractionator and blends the fractionator liquid products into one liquid product
Take three feed types: residual oil, FCC fractionator bottoms/slurry oil, and tar/rock
Three products: gas (H2S, C1-C4), liquid (C5-302F, F, F, 650F+) and coke
ExxonMobil is implementing the reactor model in RTO
Key optimization variable
Optimizing coke drum temperature for maximum profit

20. Visbreaker Reactor (VOM)
Model the visbreaking unit including furnace/reactor, fractionator and fuel oil blend
Feeds: Resid, VGO (optional), cutter stocks. Cutters stocks bypasses reactor and do not crack.
Products:
Gas: H2S, C1-C4; Liquid: naphtha, gasoil (can go to both liquid and fuel);
Fuel: gasoil, residue, cutter stocks
Key optimization
Optimize residence time for max profitability

21. Isomerization Reactor
Purpose: Convert n-paraffins to iso-paraffins to increase octane values
Feedstock: Light (C5-) straight-run naphtha
Reactor: Chloride promoted fixed bed
Reactions: Moderately exothermic reactions
UOP Butamer, Pentax for C4 and C5
Product: isomerate sent to gasoline pool
Similar to the Catalyst Reforming reactor, an Isomerization reactor converts straight –run naphtha from the crude tower to high octane gasoline. The difference is the feedstock for Isomerization is from the top of the naphtha splitter, while the feedstock for a reformer is from the bottom of naphtha splitter.
Usually normal straight chain paraffins have lower octane numbers than branched iso-paraffins. For instance, N-pentane has RON of 62 while i-pentane has RON of 92.
The reactor is also a fixed bed. Usually there is a hydrotreater before the reactor to remove sulfur and other impurities and saturate any olefins. The isomerization reactions are moderately exothermic reactions.
UOP has different processes for C4 and C5 using similar catalysts and technology.

22. Isomerization Reactor Model (ISOM)
Rigorous Kinetic Model
Model based on pilot plant data of UOP I-8 catalyst for Butamer and Penex processes
Feed and products are all real components
No special property prediction or modification in the model
Easy to implement because of usage of real components
Key optimization
Manipulate recycle compositions to maximize product octane numbers

23. Refinery Reactor Demo