Refining: Outline Refinery Processes Refining Markets: Capacity, Cost, Investment Optimization of Refinery Operations
Refining: Outline Refinery Processes Refining Markets: Capacity, Cost, Investment Optimization of Refinery Operations
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Refining
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   Outline
    Refinery processes
    Refining Markets: Capacity, Cost, Investment
    Optimization of Refinery Operations
 Prof. Metin Çakanyıldırım used various resources to prepare this document for teaching/training.
   To use this in your own course/training, please obtain permission from Prof. Çakanyıldırım.
         If you find any inaccuracies, please contact metin@utdallas.edu for corrections.
                                        Updated in Spring 2019
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Crude Oil  Gasoline, Fuels, LPG, Chemicals
                                                                                                                          2
Molecules      Wght %
                          Crude Oils
Alkanes              30    Inputs:
(Paraffins)
Cycloalkanes         49
(Naphthenes)
Aromatics            15
                                                         Onsite Facilities
Asphaltics            6
                                                        Refinery Complex
                                                                                          Final Products
                                                                                       Gasoline
                                                                             Outputs
Offsite Facilities: Electric power distribution; Fuel oil and fuel gas
facilities; Water supply, treatment, disposal; Plant air systems; Fire                 Jet and Heating Fuels
protection systems; Flare, drain and waste containment systems; Plant                  Liquefied Petroleum Gas
communication systems; Roads and walks; Railroads; Buildings.
                                                                                       Chemicals
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Inland Refinery: Holly Frontier’s Tulsa
                                                                                                  3
                                                               Arkansas River
                                                                   105 miles
                                                                                  Interstate 44
                                                                  Northwest of
                                                                  Oklahoma City
2.Storage Tanks
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          Final Product Storage
                                                                                     Crude Oil Operations
 1. Railways or Pipeline                                                     Receive Crude Shipments
                                                                               Continuous or in Parcels
                                                          II.                Store Crude in Storage Tanks
                                                        Refining               Hedge against crude unavailability risk
                                                         Oper.                 15-day thruput storage often adequate
                                2. Storage
                                  Tanks                                      Use Staging Tanks
                                                                               Mix different crudes
                                                  Crude Distillation Unit      Remove Brine (Salts)
                             I.                                                Hedge against input unavailability
                           Crude                                                3-4 day thruput storage often adequate
                            Oil
                           Oper.                  Other Refinery Units       Pump Crude to the Distillation Unit
                                                                             Crude oil operations are discrete processes
                            3. Staging                                       if done in parcels
                              Tanks
                                                                                      Refining Operations
                                                                             4 processes, to be detailed later
                                                                             Refining is the process of converting crude
                                                                             to usable products.
                                                                             Refining operations are continuous processes
                                                             Final Product
                                                                                     Final Product Storage
                                                             Storage Tanks
                                                                             Until train, tanker truck, tanker ship pick
                                                                             up or pipeline shipments
                           Railways or Pipeline                                Capacity with 10 days of thruput
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                Crude Distillation Unit (CDU)
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   Hydrocarbons in crude have different boiling
    temperatures.
      – At 20 oC boiling are few-carbon alkanes:
           methane (1C), ethane (2C), propane
           (3C), butane (4C)
      – Around 70 oC boiling are cycloalkanes:
           pentane (5C), hexane (6C),
      – Around 120 oC boiling is heptane (7C).
         Liquids are octane (8C), nonane (9C)
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                                 1.A. Atmospheric towers & 1.B.Vacuum towers
                                                                                 Intermediate Products                                    Final Products
                                                                     1. Distillation
                                                                    150-230 oC                                                            Kerosene, Jet fuel,
                                                                                       Kerosene
                                                                                                                                           Diesel, Fuel oil
2. Conversion Processes:
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            Decompose (Crack), Unify, Reform
Intermediate                                                                                        Final Products
  Products
                                                    Vapor Recovery
 Butane and lighter                                 Capturing gasses                               Refinery fuel gas
                                                       physically
                                                                                                       Propane
Gasoline (low octane)      Isomerization                                                                 NGL
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                 2.A. Cracking
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   Cracking: Breaking down heavier and larger HCs into lighter and smaller HCs.
      Thermal Cracking: Using heat to crack.
             Steam-cracking: Using steam to crack; sound-like steam flooding in EOG.
             Coking: Using extreme heat to crack residue to obtain coke and heavy oil.
             Visbreaking: Using moderate heat to crack with the purpose of reducing viscosity
        Catalytic cracking: Using a catalyst (facilitator) under high temperature.
             Fluid catalytic cracking (FCC): Using zeolites (aluminium + silicates) powder as catalyst
             Hydro cracking: Using water (hydrogen) as catalyst
Fluid Hydro
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    2. B. Reform and 2.C. Combine (Unify)
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   Higher Octane Level ⇒ Better combustion under pressure.
                                                                                                                       7
     –   Level indicates the amount of pressure a HC can withstand before self-ignition.               3
     –   Octane levels are defined relative to iso-octane.                                             2       5       6 8
                                                                                               1
     –   As there can be more pressure resistant HCs, octane levels >100 ok for them.
                                                                                                           4
     –   E.g.: Methane has octane number 120.
                                                                                                   Iso-octane
                                                                                                                           C
   Isomerization is changing the geometry of the molecule.                      C    C    C   C
     – This increase the octane level.                                                                             C       C              C
                                                                                                                           C
                                                                                                                   C                      C
   Reforming is obtaining cyclic HCs from chains.                     C    C     C    C   C       C
                                                                                                                   C                      C
                                                                                                                           C
   Alkylation is obtaining alkanes (saturated) HCs from non-saturated ones.
     – This yields larger molecules with higher octane levels.
                                                                                           C                       C       C               C
                                                                        C    C
                                                                                       C   C       C               C       C               C
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                                 3. Treating
             1. Distillation     2. Conversion 
3. Treatment: Preparation of HCs and finished products by using chemical / physical separation.
     –   Removing unwanted substances: Salt, Suplhur, nitrogen, oxygen, metals (lead, mercury)
           » Desalting
           » Hydrodesulfurization: Sulfur removal yields elemental sulfur that is used in agriculture (as
             fertilizer) and in pharmaceuticals. Some sulfur can remain in fuel oil and coke.
     –   Dewaxing to avoid solidification under low temperature and to improve gasoline flow in winters.
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                                   4. Blending
1. Distillation  2. Conversion  3. Treating 
4. Blending: Mixing of HCs in certain fractions to obtain finished products with specific properties.
                Power                                                Compression
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         4. Blending for Specific Properties
Ignition Properties:
 RVP (Reid Vapor Pressure) specifies evaporation characteristic of gasoline.
     –   RVP measures the surface pressure that keeps a liquid from vaporizing.
           »   High RVP ⇒ Liquid vaporizes easily. Low RVP ⇒ Liquid does not vaporize easily
     –   Liquid gasoline does not burn easily. Spraying charcoal igniter liquid on your barbeque ok, if the liquid is cold.
     –   A fuel injector sprays gasoline & oxygen at the right mix and pressure into the engine block for combustion.
           »   Injector needs 6-12 psi RVP; Higher RVP for lower temperatures and lower RVP for higher temperatures
     –   Vapor vaporizes easily under high temperature
           »   RVP of 12 psi for Fargo, North Dakota in winters; less RVP, gasoline remains as liquid and does not burn.
           »   RVP of 6 psi for Dallas, TX in summers; more RVP, gasoline vaporizes while pumping or transferring to the injector
     –   EPA needs less RVP to reduce evaporative emissions. The limits are stricter during the summer ozone season.
   Octane level: Gasoline mostly has octane C8H18 and some heptane C7H16 & others.
     –   Gasoline with octane number 90 has the same combustion properties as 90% iso-octane and 10% heptane.
     –   Similarly octane number 80 indicates the same combustion properties as 80% octane and 20% heptane.
     –   Knocking: Ignition of gasoline in the engine block on its own before being ignited by a spark plug.
           »   Self-ignition is more likely if the pressure on the gasoline is high
           »   The pressure on the gasoline is high in engines with high compression ratio
           »   Compression ratio = Highest volume of an engine block / Lowest volume of the engine block
           »   Sport cars: high compression ratio engines to obtain more power ⇒ high risk of self-ignition
                    Sport cars need less combustible gasoline, which is high octane gasoline
     –   High octane rating ⇒ smooth & sustained combustion with less combustible gas to avoid knocking
Corrosion Properties:
 Sulphur level: Crude with > 0.5% Sulphur is corrosive (sour).
 TAN (Total Acid Number) is the concentration of potassium hydroxide (KOH, a base) needed to
    neutralize the acid in the crude. Crude with TAN > 1 mg KOH/g is corrosive.
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                        4. Blending Computations
4. Blending:
     Octane level:
             Gasoline with different octane levels can be blended
             50-50 Blending of 90 octane gasoline with 80 octane gasoline yields 85 octane gasoline.
             20-80 Blending of 90 octane gasoline with 80 octane gasoline yields 82 octane gasoline.
                   82=(0.2)90+(0.8)80
             Suppose we are selling mid-grade gasoline with 88 octane. In what proportions should we blend 90 octane
              gasoline and 80 octane gasoline to obtain 88 octane gasoline?
                    88=90x+80(1-x) gives x=0.8.
     These linear blending computations are assumed to be valid for sulfur content, TAN & RVP, i.e., for a
      characteristic 𝐶𝐶𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏, we obtain it from the characteristic 𝐶𝐶𝑖𝑖 of the ingredient 𝑖𝑖 by using volume (or weight) 𝑉𝑉𝑖𝑖 .
           Take a weighted average of characteristics where weights can be relative volumes (weights)
                                                                                      𝑉𝑉𝑖𝑖
                                             𝐶𝐶𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 =       �                                 𝐶𝐶𝑖𝑖
                                                                              ∑𝑗𝑗∈Ingredient 𝑉𝑉𝑗𝑗
                                                              𝑖𝑖∈Ingredient
                                                                                                                                     1
                                                                                                                                    1.25
                                                                                                           𝑉𝑉𝑖𝑖
              There also is a nonlinear but more exact formula for RVP: 𝑅𝑅𝑅𝑅𝑃𝑃𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 = ∑𝑖𝑖 ∑                    𝑅𝑅𝑅𝑅𝑃𝑃𝑖𝑖1.25
                                                                                                           𝑗𝑗 𝑉𝑉𝑗𝑗
              The nonlinear blending equation above is suggested by William Jackson, Merit 18.
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Preference for Alcohol over Lead in the Engines
                             Ethyl Cooperation (www.ethyl.com) founded in 1923 ran
                              ads like the one on left. This ad is from National
                              Geographic 1931 – 8 years after Ethyl’s founding.
                             The “Ethyl Fluid” mentioned in the ad is to
                               –   “deliver power … with a smoothly increasing pressure”
                               –   rather than “sharp, irregular bursts (that cause power-waste,
                                   harmful knock and overheating)”
                             Ethyl component CH3 CH2 − [?]
                                                                          C      C       ?
                         has an open bond to connect with [?]
                                                                          − Lead is toxic
                                                      Pb                  + But radiation shield
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                Refinery Operations and Yields
I.      Crude oil receipt and operations
        1.   Mix
        2.   Desalt
II.    Refining operations
        1.   Distillation                                           Refinery yields in US in 2003:
               a)    Atmospheric                                         – 46.9% Gasoline
               b)    Vacuum                                              – 23.7% Distillate fuel oil (inc. Diesel)
        2.   Conversion                                                  –    4.2% Residual fuel oil (heating & ship fuel)
               a)    Cracking                                            –    9.5% Jet Fuel
                       i.   Thermal Cracking: Steam-cracking,            –    5.1% Coke
                            Coking, Visbreaking                          –    3.2% Asphalt
                       ii.  Catalytic cracking: Fluid catalytic          –    4.2% Liquefied gas
                            cracking, Hydro cracking
               b)    Reforming                                      Refinery yields in Europe p.168 of GOGI:
                       i.   Isomerization                                – 21% Gasoline + 6% Naphta
                       ii.  Reforming                                    – 36% Distillate fuel oil
               c)    Combining (Alkylation)                              – 19% Residual fuel oil
        3.   Treating                                                    –    6% Kerosene used in Jet Fuel
               a)    Desalt                                              –    9% Residuals like Asphalt
               b)    Hydrodesulfurization                                –    3% Petroluem gas like Liquefied gas
               c)    Dewax
        4.   Blending                                           More gasoline in US. More Diesel & Fuel oil in Europe.
III.   Final product storage and shipment
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Refinery Markets:
Capacity, Cost, Investment
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Refinery Characteristics: Types and Products
                                                 Atmospheric distillation               Vacuum distillation
                    Cracking
                                  Topping
                                  refinery
     refinery
                    refinery
     Coking
      Simple refineries have low margins and are owned by small & niche companies.
      Complex refineries have higher margins.
         –      Their margins ↑ when the spread (light sweet crude price − heavy sour crude price) ↑
      Refinery outputs are commodities
         –      Gasoline (aviation, car and light distillates); Middle distillates (diesel fuel, jet fuel, heating oil); Other
                products (lubricants, wax, solvents, machine oils)
         –      Output markets are more segmented by location, regulation, season, quality.
         –      Product prices are related to crude prices whose prices are volatile.
         –      Product prices are volatile as demand is inelastic in the short-term.
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           Refining Characteristics: Margins
   Refineries, capital-intensive, long lifetime, very specific physical assets
     –   Cost of a refinery.
     –   High initial investment and exposure to financial risk: interest rate, investment cycle, crude cost.
     –   Gross margin = Revenues from product sales – Cost of crude was $8.68 per barrel in 2004.
     –   Net Margin = Gross margin – Cost of (marketing + internal energy + operating) was $3 per barrel in 2004.
     –   Booms and Busts: Profitability of refinery peaked in 1988 and 2001: 15%. It plunged to -1.7% in 2002.
                           Complexity          US           Gross Margin       Net Margin
                                             Capacity         $/barrel          $/barrel
                           Topping                 5.6%           0.5 to 1.5      -0.5 to 1.5
                           Cracking               28.7%             3 to 4.5         0 to 2.5
                           Coking                 65.7%               5 to 7         0.5 to 4
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           Refining Characteristics: Pollution
   Refineries create pollution
     – Pollution gases emitted during refining operations: Particle matter (dust, dirt, smoke, soot), Sulfur dioxide, Carbon
         monoxide, Nitric oxides, Volatile organic compounds (paints, adhesives). All of these are created by catalytic
         cracking and coking units.
     – Pollution created by refinery products such as gasoline. Reducing the pollution from burning gasoline?
     – Refineries are subject to several regulations.
            »   Air Acts: Clean Air 1963, amendments 1967, 1970, 1975, 1977, 1990. Motor Vehicle Air Pollution 1965. Air Quality 1967.
            »   Water Act: River and Harbor, Refuse, Federal Water Pollution Control, Clean Water, Water Quality, Safe Drinking Water.
     –   ConocoPhillips’ Sweeney Refinery located in Old Ocean, TX, 65 miles southwest of Houston, has a crude oil
         processing capacity of 247 MBD. It processes mainly heavy, high-sulfur crude oil, but also processes light, low-
         sulfur crude oil.
            » Facilities: fluid catalytic cracking, delayed coking, alkylation, a continuous regeneration reformer and
              hydrodesulfurization units.
            » Input: Domestic and foreign crude oil, received primarily through wholly and jointly owned terminals on the Gulf
              Coast, including a deepwater terminal at Freeport, TX.
            » Output: A high percentage of transportation fuels (such as gasoline, diesel fuel and jet fuel). Other products include
              petrochemical feedstocks, home heating oil and coke.
            »   The refinery operates nearby terminals and storage facilities in Freeport, Jones Creek and on the San Bernard River, along with pipelines that connect
                these facilities to the refinery.
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           Major Equipment Estimates
   Onsite facilities of a refinery cost: $ 82,976 K:                                                   360,00 gallons in 150 x 150 m2
     –      Desalter $1,800 K for 30,000 BPSD (=barrels per stream day)
                                                                                                                                            150 m
                                                                                                      25 m
         Barrel per stream day BPSD = max # of barrels of input a distillation unit can process)              9m
     –      Atmospheric distillation unit $27,000 K for 30,000 BPSD
     –      Vacuum distillation unit $14,500 K for 18,000 BPSD
     –      Naphtane desulfurization unit $6,600 K for 4,000 BPSD
     –      Reforming unit $11,000 K for 3,000 BPSD
     –      Catalytic reformation unit $600 K.
     –      Cold water system $824 K for 8,240 gallons per minute.
     –      Steam system $2,472 K for 30,900 pound per hour.                                       2290 m3 =Volume of tank height 9 m, radius 9 m
                                                                                                      57,143 m3 = 25 tanks each with 2,290 m3
     –      Storage $18,000 K for 12 days thruput                                                       57,143 m3 ≤ 3 tanks with 20,000 m3
          Storing 360,000=12*30,000 barrels at the cost of $50/bbl storage capacity                1 m3 = 6.3 barrels, 360,000 barrels = 57,143 m3
   Offsite facilities: Electric power distribution; Fuel oil and fuel gas facilities; Water supply, treatment,
    disposal; Plant air systems; Fire protection systems; Flare, drain and waste containment systems; Plant
    communication systems; Roads and walks; Railroads; Buildings.
     –      For a midsize refinery offsite costs are 30% of onsite facility cost.
     –      Offsite facilities cost: $ 24,839 K.
   Location factor: Location determines climate (affects design & construction costs), local rules & taxes.
     –      US Gulf coast refineries are relatively cheaper and have location factor of 1.0.
     –      St. Louis has a factor of 1.4. Alaska North Slope has a factor of 3.0.
   Contingencies: 15% allowance for major loopholes and inaccuracies.
   Cost of a midsize refinery in St. Louis in 1994 was about $174 million.
     –      (82,976) (1.3) (1.4) (1.15)=173,582
      Source: Cost Estimation. Chapter 17. Petroleum Refining: Technology and Economics, 3rd ed. by J.H. Gary, and G.E. Handwerk 1994.
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        Take Inflation Factor into Account
   We have found the cost of a simple refinery to be $174 million in 1994. To bring it to 2010 use:
   Cost in year (t) = [Cost in year (s)] * [Index in year (t) / Index in year (s)]
   Cost in year 2010 = [Cost in year 1994] * [2,337.6 / 1,349.7] = 174 * 1.732 = $ 301.36 Million.
   If this refinery were to be built in Alaska North Slope, the cost would be
     = 301.36*[(Location factor in North Slope)/(Location factor in St. Louise)]
     = 301.36*(3/1.4)
     = $ 646 Million.
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              Cost of Capacity and Complexity
   Cost of a 𝑞𝑞 =30,000 BPSD refinery in Alaska in 2010 has been found to be $ 646 Million.
   The cost increases but does not double if we double the capacity. In particular,
           Cost of capacity 𝑄𝑄 = Cost of capacity 𝑞𝑞 ∗ (𝑄𝑄/𝑞𝑞)0.6.
   Doubling the capacity in Alaska, the cost of refinery increases to 646 (2) 0.6 = $ 979 Million.
   A rough estimate of refinery cost is $15,000 for each BPSD.
     – Using this, the cost of a 60,000 BPSD refinery turns out to be $900 Million, similar to the detailed estimate
         obtained for the same size refinery in Alaska.
     – However, this rough estimate becomes $450 Million for a 30,000 BPSD refinery whose detailed cost estimate is
         $ 646 Million. The rough cost estimate can be inaccurate by about 50%.
   Complexity of a refinery can be defined in terms of complexity of its units.
     – Complexity of atmospheric distillation unit ← 1. This unit gives the most output (BPCD) per $ invested.
                                                                        Cost of 𝑡𝑡𝑡𝑡𝑡𝑡𝑡 𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢 𝑝𝑝𝑝𝑝𝑝𝑝 𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵
                     𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑜𝑜𝑜𝑜 𝑎𝑎 𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢 =
                                                               Cost of 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 𝑝𝑝𝑝𝑝𝑝𝑝 𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵
           » If a 100,000 BPCD       distillation unit  costs $10 Million, the cost per BPCD is $100.
           » If a 20,000 BPCD catalytic reforming unit costs $10 Million, the cost per BPCD is $500.
           » Catalytic reforming is 500/100=5 times more complex than atmospheric distillation.
     – Some example complexities: Catalytic Hydrocracking 6; Alkylation 10; Isomerisation 15; Lubricants 60.
     – This complexity definition dates back to 1960s and was developed by W. Nelson.
   US Refinery complexity by company in 2003:
     – Valero 13.4; Exxon 12.8; ChevronTexaco 12.3; BP 11.6; Citgo 11.4; Shell 11; Marathon 10.6; ConocoPhillips
        10.3; Premcor 9.4; Sunoce 8.7; Tesore 8.5.
     – “Higher complexity allows Valero to process cheaper higher sulfur crudes while maintaining a highly desirable
        product slate. Higher complexity usually means more energy input per barrel of crude.”
                    Source: Valero Energy Strategy. G. Faagau, Director, Energy Optimization, Valero Energy Corporation.
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                                When to Invest?
          350
          150
                         Refining capacity in 100,000 BPCD
          100
50
               0
                1979              1984               1989               1994               1999               2004               2009
                                                                        Investment
                                                                          Window
                                                                      Higher margin
                                                                      Lower uncertainty
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      US Refining Capacity and Structure
   US refining capacity (of Atmospheric Oil Distillation column)
     – was 19.4 million BPCD (Barrels per calendar day) in 1981.
     – is 17.7 million BPCD in 2011.
   Vacuum distillation capacity is 8.6 million BPCD. Thermal cracking capacity is 2.7 million BPCD.
    Catalytic hydro-cracking capacity is 1.9 million BPCD.
   Although the number of refineries significantly dropped from 324 in 1981 to 148 in 2011, the capacity
    did not.
     – Existing refineries expanded their capacities.
     – Expansion is more economic than a brand-new facility.
          » Economies of scale
          » Regulatory requirements are easier to overcome.
     – Top 3 US refineries process 36% of the crude oil; top 10 process 77%.
     – Concentrated ownership: There are fewer companies owning refineries now than before.
     – Diverse ownership: Vertically integrated major companies used to own most of refining capacity.
       Now midsize and independents are also involved in refining. Various ownership structures exist:
          »   Holly Frontier (2828 N Harwood St, Dallas, TX 75201) is on its own and public.
          »   Motiva enterprises (of Houston) 50-50 joint venture between Royal Dutch Shell & Saudi Refining.
          »   Koch industries is privately owned.
          »   ConocoPhillips is separating its production (upstream) from refining (downstream). Separation is
              expected to be completed in the second quarter of 2012. Downstream company will be called Phillips 66.
     – Regardless of ownership structure, refineries tend to be run as separate profit centers.
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         US Refineries and PAD Districts
                                                              From\To      I        II        III       IV     V
                                                              I                      123            2
II 27 81 20
IV 23 52 12
                                                              V
                                                                   Shipments in Million Barrels in 2004
                                                                   of petroleum products among PADDs
   PADDs (Petroleum Administration for Defense Districts) were established during WW II.
     –   PADD I: East: CT, ME, MA, NH, RI, VT, DE, DC, MD, NJ, NY, PA, FL, GA, NC, SC, VA, WV
     –   PADD II: Midwest: IL, IN, IA, KS, KY, MI, MN, MO, NE, ND, SD, OH, OK, TN, WI
     –   PADD III: South: AL, AR, LA, MS, NM, TX
     –   PADD IV: Rockies: CO, ID, MT, UT, WY
     –   PADD V: West: AK, AZ, CA, HI, NV, OR, WA
   US Capacities. PADD I 1.7; II 3.6; III 8.1; IV 0.6; V 3.2 million BPCD in 2005.
   Global Capacities. Africa 3.2; Asia 22.2; Eastern Europe 10.2; Middle East 7.0; North America 20.6;
    South America 6.6; Western Europe 14.9 million BPCD in 2005.
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Optimization of Refinery Operations
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                        Optimization of a Refinery
   A simple refinery receives 20,000 barrels of crude A and 30,000 barrels of crude B.
   Crudes have 4 processes: Distillation (light & middle), reforming, cracking (regular & coking), blending.
   Distillation separates crudes into
                                          Cycloalkanes
                         Output/        Light         Medium        Heavy        Light          Heavy        Residuum
                         Input         Naphta         Naphta        Naphta        Oil            Oil
                         Crude A            0.10          0.20          0.20            0.12         0.20           0.13
                         Crude B            0.15          0.25          0.18            0.08         0.19           0.12
   Light, medium and heavy naphtas have octane numbers 70, 80, 90. Light ignites faster.
   Naphtas can be blended to produce refined products or can go to reforming.
      Reforming’s output is reformed gasoline with octane number 115. Yield of each barrel of naphta:
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             Processes Map and Yields Partial
Crude A     Crude B
                                                                                      Premium
   Distillation
                                                                         Blending
                                                                         Distillate
                                                                                      Gasoline
                                                                          Light
 Numbers not shown
                                                                                      Regular
Light Naphtha
                                       0.60                                           Gasoline
                         Reforming
                                     0.52      Reformed
Medium Naphtha
                                               Gasoline
                                        0.45
Heavy Naphtha                         1 barrel of heavy naphta yields
                                      0.45 barrel of reformed gasoline
                                             0.20 Gasoline
                                             0.68 Cracked
Heavy Oil                                           Oil                               Jet Fuel
                                          0.75
                        1 barrel of heavy oil yields
                                                                         Blending
                                                                         Distillate
                                                                          Middle
                        0.20 barrel of cracked gasoline
                        0.75 barrel of cracked oil                                    Fuel oil
                          Coking
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                    Optimization of a Refinery
   Residuum can be used for producing lube oil or middle distillate blending in to jet fuel and fuel oil.
    Yield of each barrel of residuum is below.
                                                          Residuum
   Regular and premium are two types of gasolines obtained by light distillate blending naphtas,
    reformed gasoline and cracked gasoline. Their octane numbers must be at least
                                                Regular gasoline       Premium gasoline
Octane number ≥ 84 94
   Jet fuel is obtained by blending light, heavy, cracked oils and residuum. Its RVP (Reid Vapor
    Pressure) must be less than 1 kg/cm2. The pressures of the inputs are as follows.
                                    Light oil       Heavy oil        Cracked oil    Residuum
   Fuel oil is obtained by blending cracked, light, heavy oil and residuum in the ratios of 3:10:4:1.
      E.g., blending 3 barrels of cracked oil, 10 barrels of light oil, 4 barrels of heavy oil and 1 barrel
         of residuum results in 18 barrels of fuel oil.
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      Processes Map and Yields Completed
Crude A     Crude B
                                                                               Premium
                                                                               Gasoline
                                                         Blending
                                                         Distillate
   Distillation
                                                          Light
                                                                               Octane≥ 94
Light Naphtha
                                    0.60                                       Regular
                      Reforming
                                  0.52     Reformed                            Gasoline
Medium Naphtha                                                                 Octane≥ 84
                                           Gasoline
Heavy Naphtha                       0.45
                                        0.20 Gasoline
                                        0.68 Cracked
Heavy Oil                                      Oil                             Jet Fuel
                                     0.75
                                                                               RVP≤ 1
                                                         Blending
                                                                           3
                                                         Distillate
                                                          Middle
                                                                      10       Fuel oil
                                                                       4
                                                                           1
                       Coking
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       Process Capacities, Limits and Prices
Capacities:
 Distillation Capacity 45,000 barrels per day.
 Reforming capacity is 10,000 BPD.
 Cracking capacity is 8,000 BPD.
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                Processes with Decision Variables
Crude A CA       Crude B CB
                                    LNPG+LNRG
                                                                                                 Premium
                                       MNPG+MNRG
                                                                           Blending
                                                                           Distillate
    Distillation                                                                                 Gasoline PG
                                                                            Light
                                           HNPG+HNRG                                             Octane≥ 94
                                              RGPG+RGRG
 Light Naphtha   LN           LNR                CGPG+CGRG
                                        0.60                                                     Regular
                                    Reforming
                                                                                                 Gasoline RG
 Medium Naphtha    MN         MNR               0.52     Reformed
                                                                                                 Octane≥ 84
                                                       Gasoline ReG
                                                               Cracked
                                                      0.20   Gasoline CG
                              HOC                     0.68     Cracked
 Heavy Oil HO                                                                                    Jet Fuel JF
                                                   0.75        Oil CO
                                                                                                 RVP≤ 1
                                                                           Blending
                                                                                             3
                                                                           Distillate
                                                                            Middle
                               LOB
                                 HOB                                                    10       Fuel oil   FO
                                                                                         4
                                   RB                                                        1
                                     Coking
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                                   Constraints
   Contractual availability of crudes      CA≤ 20,000; CB ≤ 30,000.
 Daily lube oil production must be between 500 and 1000 BPD.
                                         PG ≥ 0.4 RG.
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                        Constraints: Distillation
   Distillation separates crudes into light, medium, heavy naphta, light, heavy oil and residuum.
                                      CA           CB
                        LN               0.10         0.15               LN = 0.10 CA + 0.15 CB;
                        MN               0.20         0.25               MN = 0.20 CA + 0.25 CB,
                        HN               0.20         0.18               HN = 0.20 CA + 0.18 CB,
                        LO               0.12         0.08               LO = 0.12 CA + 0.08 CB,
                        HO               0.20         0.19               HO = 0.20 CA + 0.19 CB,
                        R                0.13         0.12                R = 0.13 CA + 0.12 CB.
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                    Constraints:
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        Naphta, Light, Heavy Oil, Residuum
   Naphta balance equation        LNPG+LNRG
                                      MNPG+MNRG                             Premium Gasoline   PG
                                        HNPG+HNRG                           Regular Gasoline   RG
                                                     Reforming
                                      MNR
          Medium Naphtha    MN                                            MN = MNPG + MNRG + MNR,
                                      HNR                                 HN = HNPG + HNRG + HNR.
          Heavy Naphtha   HN
             Light Oil LO
                                   LOC    Cracking
                                                                            LO = LOC + LOB,
                                  HOC                                       HO = HOC + HOB.
             Heavy Oil HO
                                    LOB
                                      HOB
                                         RB
                                                                             R = RC + RB.
                                                                 Coking
                                         RC
              Residuum    R
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                         Constraints:
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                  Process Balance Equations
   Reforming balance equations
            LNR
                    Reforming     0.60
                                0.52
                                                                     ReG = 0.60 LNR + 0.52 MNR + 0.45 HNR.
           MNR                             Reformed
                                         Gasoline   ReG
            HNR                   0.45
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                     Light Distillate Blending
   Reformed and Cracked Gasoline balance equations
                      RGPG+RGRG
                     Cracked
                    Gasoline CG
        LNPG+LNRG
        MNPG+MNRG                           Premium Gasoline   PG
                          Blending
                          Distillate
                           Light
        HNPG+HNRG
        RGPG+RGRG
                                            Regular Gasoline   RG
        CGPG+CGRG
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               Recipe for Fuel Oil
   Middle Distillate Blending
                                                                                                  Jet Fuel
         To produce 180 barrels of FO, we blend                                                  JF
                                                                 CO
            30 barrels of Cracked Oil,
                                                                            Blending
                                                                                              3
                                                                            Distillate
                                                                             Middle
           100 barrels of Light Oil to Blending,                 LOB
                                                                 HOB                     10       Fuel oil
            40 barrels of Heavy Oil to Blending,                                          4       FO
            10 barrels of Residuum to Blending.                   RB                          1
         If we have,
             70 barrels of CO, 40 barrels extra goes into JF,
            110 barrels of LOB, 10 barrels extra goes into JF,
             40 barrels of HOB, 0 barrels extra goes into JF,
             60 barrels of RB, 50 barrels extra goes into JF.
         CO ≥ (3/18) FO;         LOB ≥ (10/18) FO;               HOB ≥ (4/18) FO;             RB ≥ (1/18) FO,
         JF = (CO - (3/18)FO ) + (LOB - (10/18)FO) + (HOB - (4/18)FO) + (RB - (1/18)FO).
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                         Constraints:
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                  Octane and Vapor Pressure
   Octane numbers
                                                                                  Regular    Premium
     Light, medium and heavy naphtas have octane numbers 70, 80, 90.              gasoline   gasoline
     Reformed gasoline has octane number 115.
                                                                       Octane
     Cracked gasoline has octane number 105.                           number ≥         84                    94
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                                    Objective
 Maximize the revenue from final products whose prices are $/barrel
   Inputs come through an existing contract. They are fixed and their costs are sunk.
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       Recipe for Jet Fuel in addition to Fuel Oil
                                                                                                                         New
   Middle Distillate Blending                                                                                    requirement
                                                                               CO
        Suppose that JF needs to be produced now by blending cracked,                                      2
                                                                                        Blending
                                                                                        Distillate
                                                                                         Middle
         light, heavy oil and residuum in the ratios of 2:4:1:1. This          LOB                                  Jet Fuel
                                                                                                       4
         modification is inspired by a question from Juan Vanegas Merit’14.    HOB                                     JF
                                                                                                       1
        To produce 80 barrels of JF, we blend                                  RB                          1
            20 barrels of CO,
            40 barrels of LOB,
            10 barrels of HOB,                                                                                      Existing
            10 barrels of RB.                                                  CO                               requirement
                                                                                       Blending
        If we want 80 barrels of JF and 180 barrels of FO, we need at least
                                                                                       Distillate
                                                                                                            3
                                                                                        Middle
                                                                               LOB
           20 and 30 barrels of CO respectively for JF and FO,                                         10           Fuel oil
                                                                               HOB
           40 and 100 barrels of LOB respectively for JF and FO,                                        4             FO
                                                                                RB
           10 and 40 barrels of HOB respectively for JF and FO,                                             1
           10 and 10 barrels of RB respectively for JF and JO.
    Jet fuel RVP must be less than 1 kg/cm2. When CO, LOB,                    Light   Heavy         Cracked        Residuum
     HOB and RB are mixed at ratios of 2:4:1:1, the JF has                      oil     oil            oil
     RVP of (2/8)1.5 +(4/8)1 +(1/8)0.6 +(1/8)0.05 = 7.65/8 < 1. RVP              1.0       0.6              1.5             0.05
     No RVP constraint is necessary!
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                                     Refinery Optimization in Practice
Refinery Operations Flowchart
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                            Texas Refinery Context
Texas refinery obtains 3 intermediate products (components) C1, C2, C3 after distillation/conversion and
plans to use these to produce 2 coatings: MightyPlate and Aluminum.
   The sales price of coatings are $1.15 / litre for MightyPlate and $ 1.30 / litre for Aluminum.
   Texas refinery has a contract to produce at least 10,000 liters of MightyPlate.
   The cost of producing 3 components (through purchasing crude, distillation, conversion) are $0.45 / litre for C1,
    $0.55 / litre for C2 and $0.75 / litre for C3.
   With current processes & input, the refinery can produce 4000 liters of C1, 7000 liters of C2 and 8000 liters of C3.
   There are technological constraints while blending components to make the coatings
         MightyPlate can contain at most 55% C1 and at most 25% C3 and must contain at least 35% C2
         Aluminum can contain at most 45% C2 and must contain at least 15% C1 and 25% C3.
   The processing (including treating and blending) costs are given as ¢ / litre by the table below
                                                       C1       C2       C3
                                   MightyPlate            12       15       10
                                   Aluminum               18       13       20
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          Texas Refinery Context Visualization
Crudes
2. Conversion
Out of context
                                                                 Cost $0.20/litre       A
                  Cost $0.75/litre        C3                                                 Price $1.30/litre
                  𝐶𝐶𝐶 ≤ 8,000 litre
                                                     3. Treating & 4. Blending
                             Technological constraints
                                          M can contain ≤ 55% C1 and ≤ 25% C3 and must contain ≥ 35% C2.
                                          A can contain ≤ 45% C2 and must contain ≥ 15% C1 and ≥ 25% C3.
                                                            Context
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                                     Texas Refinery
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                           Ingredients of a Formulation
                 To formulate: Define decision variables for each arrow:
                               𝐶𝐶𝐶𝐶𝐶, 𝐶𝐶𝐶𝐶𝐶, 𝐶𝐶𝐶𝐶𝐶, 𝐶𝐶𝐶𝐶𝐶, 𝐶𝐶𝐶𝐶𝐶, 𝐶𝐶𝐶𝐶𝐶
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Formulation: Objective Function and Constraints
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Summary
     Processes
     Markets
     Optimization
  Based on
  -     Introduction. Chapter 1 of Petroleum Refining: Technology and Economics, 5th edition by J.H.
        Gary, G.E. Handwerk and M.J. Kaiser 2007.
  -     Refining Process Handbook. Surinder Parkash. Published by Elsevier. 2003.
  -     A Guide to Oil and Gas Industry (GOGI). By Deutsche Bank Market Research, 163-187.
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    Optimization of Crude Oil Operations
   See http://newton.cheme.cmu.edu/interfaces/crudeoil/main.html
   X. Chen, I. Grossmann, L. Zheng. 2012. A comparative study of continuous-time models for
    scheduling of crude oil operations in inland refineries. Computers and Civil Engineering,
    Vol.44:141-67. Articles by Modules/Refining/ChenComparingModelsSchedulingRefineries