2013 AIChE Annual Meeting. Characteristics of Heavy Fractions for Design and Operation of Upgrading Related Processes

Transcription

1 2013 AIChE Annual Meeting Characteristics of Heavy Fractions for Design and Operation of Upgrading Related Processes M. R. Riazi, Ph.D., AIChE Fellow Professor of Chemical Engineering Kuwait University San Francisco, California November 7, 2013 (2:45 3:00 PM) Room: Van Ness, Hilton Paper 653j in Session: Alternative Fuels and Enabling Techniques I: Fuels and Petrochemicals Division

2 Summary of Presentation Review of upgrading processes Characteristics of heavy fractions Application of a Distribution Model for Properties of Heavy Fractions Upgrading heavy oil with gas dissolution, a measurement technique Concluding Remarks 7,

3 Introduction While world demand on lighter fuels such as naphthas and middle distillates of crude oils is on the rise, quality of world crude is decreasing and extra heavy crudes and unconventional oils are alternative to conventional and more sweet oils. Future refineries are dealing with conversion of nearly all residues to light and middle distillates through various separation and cracking processes. Optimum operation of such units depend on the knowledge of feedstocks and products physical properties. 7,

4 Production of Heavy Oil is Rising 7,

5 Heavy oil and bitumen resources and their worldwide distribution 7,

6 Various categories of natural gas and liquid naturally occurring petroleum fluids and their approximate hydrocarbon molecular weight distributions according to their carbon numbers natural gas gas-condensate(ngl) light crude intermediate crude heavy oil tar sand oil shale 6

7 Classification of Oils and Definition of Heavy Oil, Extra Heavy Oil and Bitumen Type of Oil API Gravity Viscosity in the Reservoir Definition of Oil Conventional Oil >45º Condensate 22º to 45º Medium - light crude Non Conventional Oil 10º to 22º <10º <10000cSt at reservoir conditions <10000cSt Mobile at reservoir conditions Heavy crude Extra heavy crude <10º >10000cSt Immobile at reservoir conditions Bitumen 7

8 Properties of light, heavy and extra heavy crudes and residue Classification Definition Extra light High API gravity, low S, N and negligible aphaltene and metals Light crude Medium range API gravity, low S, N, metals and moderate asphaltene Heavy crude Medium range API gravity, high S, N, high metals and asphaltene Extra-heavy/ Residue Low API gravity and very high contaminants (S,N, metals and asphaltenes) 8

9 Distillation Fraction, vol. % Effect of API gravity on the residue and lighter fraction (Middle Distillate) 70 Residuum Lubes Gasoline+Naphtha+MD API gravity 9

10 V, wppm. Relationship between different properties and composition of various crude oils V, wppm. Ni, wppm. Viscosity, cpo. wt. % Resin Asphaltene API Gravity API gravity Asphaltene, wt. % Ni, wppm 10

11 Metal content, wppm. Content of metals in different fractions of crude oils 900 Ni V Mg 600 K Na Asphaltene Resin DOA Heavy Crude Oil Fractions 11

12 S, wt. % N, wt. % Sulfur and Nitrogen Contents of Heavy Oil Sulfur and Nitrogen Contents in Light, Heavy, Extra-Heavy and Bitumen (, Sulfur;, Nitrogen) 10 Heavy (Extra Heavy) Crude Oil Production Increasing Light Crude Oil Production Decreasing API gravity 12

13 S, wt. % Effect of variation in Maya crude oil properties (API gravity and sulfur content) during one and half year time June wppm S API January API gravity 13

14 Properties of Typical Asphaltenes, Resins and Oils M is molecular weight in g/mol. H% is the hydrogen content in weight %. H/C is the hydrogen to carbon atomic ratio. V is the liquid molar volume at 25 ºC. d is molecular diameter calculated from average molar volume in which for methane molecules is about 4 ºA (10-10 m). D is the dipole moment in Debye. These values are approximate and represent properties of typical asphaltenes and oils. For practical calculations for resins one can assme M=800 g/mol and for a typical monomeric sphaltene separated by n-heptane approximate values of some properties are as: M = 1000 g/mol. Density of liquid Density of solid 1.1 g/cm 3. Enthapy of fusion at the melting Hydrocarbo ns M H% H/C V d, ºA D Asphaltene Resin Oil

15 Carbon number and boiling range of petroleum products 15

16 Review of Hydrocracking and Hydroprotreating Processes 16

17 Commercial Fuel (gasoline, diesel, jet fuel, heating oil, asphalt, lubricants, petrochemicals etc.) Heavy or Extra heavy crude oil Non-catalytic Catalytic Distillation A comprehensive schematic flow diagram of typical oil refinery technologies for upgrading of heavy, extra-heavy crude oil and residue (ASTM MNL58) Gas LPG Distillates ( < 343 C) Gas Gas FT-Synthesis Primary processes Secondary process Residue +H 2 Hydrotreating RDS VRDS HYVAL OCR Hydrocracking H-Oil LC-Fining HYCON ABC Fluid Cracking Hydroprocessing Coking Delayed coking Fluid coking Flexi-coking +H 2 Hydrovisbreaking SDA DOA DAO Asphaltenes Gasification Syngas 7,

18 Proposed hybrid process scheme for upgrading of heavy petroleum [MNL58] Gas Crude oil Distillation Column Hydroprocessing High value (Middle distillates) Residues (AR or VR) Solvent Recovery Solvent Deasphalting Asphaltene s Gasification Process Hydroisomerization Fischer-Tropsch Synthesis Coke (ash) 18

19 Typical Characteristics of light crudes vacuum residua compared with the Maya heavy crude vacuum residua Vacuum Resid Properties Unit Arabian Light Arabian Heavy Ural Odessa Maya 538+ C 538+ C 538+ C 538+ C Yield v % Yield wt% Density at 15 C g/ml Specific gravity at 15,6/15,6 C g/ml API API Sulfur wt% Kinematic Viscosity 135 C cst C cst , Viscosity Brookfield Viscosity 135 C cp 5, ,100 Viscosity 150 C cp ,0 3,673 TAN mg KOH/g Nitrogen ppm Nickel ppm Vanadium ppm Sodium ppm 1.3 < Concarbon wt% Asphaltenes wt%

20 Crackability tendenecy reduces with increase in aromatic content of the oil [MNL58] 7,

21 Typical Characteristics of Venezuelan and Canadian Crudes and their Vacuum Residues (ASTM MNL58) 7,

22 Factors Affecting the Conventional Hydrotreating Reactors 7,

23 Relative Activity of Different Hydroprocessing Catalysts [MNL58] (MoS: Molybdenum Sulfie, CoS: Coballt Sulfide, NiS: Nickle Sulfide, WS: Tungsten Sulfide) 7,

24 Characterization Methods for Heavy Fractions 24

25 Nature of petroleum fluids hydrocarbons 25

26 Importance of Characterization in Process Engineering Always remember that a process simulator always do not provide you with the most accurate design calculations. In general Any Process Junk input Simulator junk output results To get a good output use good input to a simulator. A good characterization method provides good input for a simulator resulting in optimum design and operation of plants. 26

27 Importance of Characterization in Process Design and Operations 27

28 Properties of Heavy Oils A Versatile Distribution Model The bulk average property is calculated as: A and B can be calculated from linear regression procedure Or in terms of probability density function (PDF) can be written as: P could be Tb, MW, or SG. For example, in terms of boiling point distribution the PDF is: 28

29 Properties of Heavy Oils A Versatile Distribution Model Fig. 6. Comparison of various distribution models for molar distribution of a heavy residue 29

30 Case Study I: Application to Single Stage Distillation of a Crude Oil Fig 9. Schematic of a single stage distillation unit operating at Ts and P 30

31 Case Study I: Application to Single Stage Distillation of a Crude Oil Model Prediction with Data Figure 10- PDF for Products of Russian Crude at 400 C based on Lee-Kesler Vapor Pressure. 31

32 PROBABILITY DENSITY FUNCTION, 1/K Applications in design and operation of a distillation column Separation of Oil and Gas in a Separator CRUDE FEED LIQUID PRODUCT VAPOR PRODUCT BOILING POINT, C 32

33 Wt% Component Concentrationn Application in Solid Wax Separation Phase Partition: Feed to Liquid & Solid Phases n-paraffin Carbon Number Series1 Series2 Series3 33

34 Second Case Study: Vacuum Gas Oil Hydrocracking and Prediction of Introduction: Distillation Data for its Products Hydrocracking (HCR) processes are commonly used in refineries for converting vacuum gas-oil (VGO) into higher-valued and lighter transportation fuels, namely, naphtha, aviation turbine kerosene (ATK), and diesel. Such processes are important for modern refineries, where hydrotreating units are upgraded to hydrocracking units. Experiments A schematic diagram of the pilot plant used for the study and its configuration is shown in Figure 1. It consists of a once-through (no recycle) microreactor followed by high and low pressure separators. 34

35 Figure 11. Schematic of the pilot plant used for the experimental runs. 35

36 Specification of pilot plant reactor used for the experimental runs Reactor Volume: 505 ml Reactor internal diameter: 2.8 cm Volume of catalyst: 128 ml Catalyst was diluted with 136 ml of carborundom. Heated feed and hydrogen are introduced in a down co-current flow mode. Reactor consists of 5 reaction zones each equipped with a built-in furnace and thermocouple to measure reactor temperature Vacuum Gas Oil (VGO) feedstock and the HCR catalyst (amorphous silica alumina) used in the runs were supplied by a local refinery. Reaction variables: Temperature (370, 380 and 390 C) and throughputs, i.e. Liquid Hourly Space Velocity (LHSV) (1.0, 1.5 and 2.0 h -1 ) Two experimental runs were considered in this work, Run-1 (18 tests) and Run-2 (29 tests). The same VGO feedstock, catalyst type and operating conditions were used for both runs. Furthermore, fresh catalyst was loaded for each experimental run. The main difference between the two runs is that for Run-2 the catalyst bed is kept on stream for longer period before starting the experimental schedule and sampling. 36

37 Specification of pilot plant reactor used for the experimental runs Sample Analysis Analysis included density and simulated distillation for liquid products. ASTM D5002 standard test method was used to measure the density SimDist ASTM D2887 standard method was used to determine the boiling range Analysis of the off-gases (for material balance) by a refinery gas analyzer (RGA) 37

38 Experimental Data Specific gravity (density at 15 C) measurements for all product samples collected for Run-1 (S1 to S18) and Run-2 (SC1 to SC29 with longer time for catalyst) are listed in Table 1. Conversion is defined as the percentage of the 288 C+ fraction of the feed cracked to lighter fractions: Density of the products decreases (lighter products) as conversion increases. 38

39 Experimental Data 39

40 Model Prediction. 40

41 Model Prediction. 41

42 Model Prediction. 42

43 Model Prediction 43

44 Final Remarks 44

45 Most Recent Applications Aug

46 References Riazi M.R., Distribution Model for Properties of Hydrocarbon-Plus Fractions. Industrial and Engineering Chemistry Research, ACS Publications 1989; 28: Riazi M.R., A Continuous Model for C7+ Characterization of Petroleum Fractions. Industrial and Engineering Chemistry Research, ACS Publications 1997; 36: Riazi, M. R., Characterization of Petroleum Fractions, ASTM International, ( HMS, Lababidi, Chedadeh, D., Riazi, M R, Alqattan, A., Al-Adwani, H. A. Prediction of Product Quality for Catalytic Hydrocracking of Vacuum Gas Oil Fuel Journal, Vol. 90, pp (2011). Riazi, M. R., Eser, S., Agrawal, S., Pena Diez, J. L. Petroleum Refining and Natural Gas Processing, ASTM MNL58, ASTM International, ( 46

47 Acknowledgement To attend 2013 AIChE Meeting was supported by Kuwait University and College of Engineering. The experiments were conducted by the researchers/staff of Kuwait Institute for Scientific Research as reported in Fuel (V 90, p, 719, 2011) 47

48 ? THANK YOU 48