OIL REFINING PROCESSES ver1

OIL  REFINING  PROCESSES Advanced  course Assoc.Prof  Pham  Huyen huyen.phamthanh@hust.edu.vn References • Chang  Samuel  Hsu  and  Paul  R  Robinson,  Practical  Advances  in   Petroleum  Processing,  Vol 1,  Springer,  2006 • Mohamed  A  Fahim,  Taher A  Alsahhaf and  Amal Elkilani,   Fundamentals  of  Petroleum  Refining,  Elsevier,  2010 Outline Unit  1  Introduction Unit  2  Refinery  Feedstocks and  Products Unit  3  Modern  Petroleum  Processing   Unit  4  Auxiliary  Processes  &  Utilities   Unit  1  Introduction Largest  Worldwide   Refineries Approximately 650  Refineries   in the  world Source:   Oil  &  Gas  Journal Unit  1  Introduction • High   sulfur,  heavy  crude  is  lowest   cost   àRequires   extremely  complex   refinery  to  convert  into  high  value   products • Low  sulfur,  light  crude  is  highest  cost     à Simple  refining  yields  high  value   products • a  function  of  location   of  crude  supply   versus  refining  centers à Refiners  close  to  crude  production   enjoy  advantage   over  refineries   distant  from   supply Unit  1  Introduction Unit  1  Introduction Note:  product  blending  and  sulfur   recovery  units  are  not  shown,  but   these  are  almost  always  present Unit  1  Introduction • DQR  Introduction • NSRP  Introduction Unit  2  Refinery   Feedstocks and  Products 2.1  Composition  of  Crude  Oils 2.2  Products  Composition 2.3  Physical  Property  Characterization  Data 2.4  Chemical  Analysis  Data 2.1  Composition   of  Crude  Oils Impurities  (sulphur,   nitrogen,  oxygen   and  metals): -­‐ low  concentrations -­‐ undesirable -­‐ affect  the  quality  of  the  produced   products -­‐ Catalyst  poisoning   and  corrosion   Waste  Water  Treatment A  refinery   typically   uses   more  water   than  crude   oil! Particulate  Emission  Control   • Wet  gas  scrubbing  (WGS)  is  very  efficient  (>90%)  for  removal  of   particulates  (4–10  mm)  from  the  FCC  regenerator  exit  Cyclones  could   be  the  first  choice  clean-­‐up  device  for  particulates   • Electrostatic  precipitators  (ESP)  employ  an  electrostatic  field  to  apply   a  charge  to  particulate  emissions  and  then  collect  them  on  grounded   metal  plates  ESP  units  are  very  efficient  (99.8%)  for  removing  finer   (4–10  mm)  particulates  from  FCC  regenerator  gas   Treatment of FCCflue gases byWGS Treatment of FCC flue gases by ESP Exercise  1  Calculating  Properties  Utilizing  UNISIM Software Process  simulators  are  used  to  characterize  crude  oil  and  determine  the   thermophysical properties  of  crude  oil  and  fractions   UNISIM  simulator  can  be  utilized  in  defining  pseudo-­‐components  of  a  crude  oil,   given  its  crude  assay  It  provides  the  option  of  selecting  the  thermodynamic  model   for  vapour–liquid  equilibrium  and  thermodynamic  properties  calculations   It  is  recommended  to  use  Peng–Robinson  equation  of  state  to  model  hydrocarbon   and  petroleum  mixtures  in  UNISIM  Detailed Consider  the  following  crude  assay  which   has  API  =  29 à Use  UNISIM  to  divide  the  crude  into   10  pseudo-­‐components  and  calculate  all   cut  properties   Solution: • The  crude  assay  (vol%  versus  TBP)  is   entered  the  oil  environment  and  oil   manager  data  entry  of  UNISIM,  and  the   number  of  pseudo-­‐components  (10   cuts)  is  entered  in  the  Blend  calculation   The  properties  calculated  by  UNISIM  are   listed  in  Table  .1 Exercise  2:  Design  of  Crude  Distillation  Units  Using Process  Simulators The  simulation  or  design  of  the  distillation  columns  involves  dividing  the  crude  oil   into  pseudo-­‐components  (Exercise  1)  Then  a  thermodynamic  model  is  chosen  for   vapour liquid  equilibrium  and  thermodynamic  properties  calculations  A  good   model  is  the  cubic  equations  of  state,  and  the  Peng–Robinson  equation  is  one  of   the  most  widely  used  models  for  hydrocarbon  and  petroleum  mixtures   Next,  the  unit  operations  stage-­‐wise  or  ‘‘tray  to  tray’’  distillation  calculations  are   performed  The  mass,  energy  balance  and  vapour liquid  equilibrium  relations  for   each  tray  are  written  and  solved  together,  subject  to  certain  specification  for  the   products  Computer  simulation  programs  such  as  UNISIM  are  used  for  quick   simulation  of  CDU  units Perform  a  material  balance  for  a  CDU  using  UNISIM  for   100,000  BPCD  of  29  API  crude  with  the  following  assay • The  crude  is   fed  to  a  pre-­‐flash  separator  operating  at   450  F  and  75  psia  The  vapour from  this  separator   bypasses  the   crude  furnace  and  is  remixed  with  the  hot   (650F)  liquid  leaving  the  furnace   • The  combined  stream  is   then  fed  to  the  distillation   column  (Figure  1)  The  column  operates  with  a  total   condenser,  three  side   strippers  and  three  pumparounds (Figure  2) Figure   Figure   Solution: In  the  oil  environment  and   oil  manager  data  entry  of  the  UNISIM  software,  the  crude  assay  is   entered  as  vol%  and  TBP  The  yield  distribution   of  the  products  is  shown   in  Figure  3 The  distillation   column  has  three  inlet  steam  streams,  with  pressures  and  flow  rates  listed  in   Table  1  The  main   distillation   column   contains  29  stages  (see  Figure  2)  The  overhead   condenser  operates  at  19.7  psia and   the  bottoms  at  32.7  psia  The  side  stripper  connections   are  also  shown  in  Figure  2 Figure   Exercise  3:  Simulation  of  ARDS  Unit • A heavy residue stream that contains mostly n-­‐C30 (990 lb mol/h) and some amount of thiophene (10 lb mol/h) is prepared to enter an ARDS process to crack the heavy component n-­‐C30 to more lighter components such as n-­‐C20, n-­‐C10 and n-­‐C4 In addition, thiophenes should be completely removed The feed stream is initially at 100F and 120 psia This feed needs to be mixed with hydrogen stream (1250 lb mol/h) available at 150F and 200 psia The mixed feed should be heated and compressed to 700F and 1500 psia before entering the reactor The reactions are shown in Table • The reactor products are cooled to 200F before entering a gas–liquid separator 300 lb mol/h of the hydrogen coming from this separator is recycled back with the feed The rest is vented to the atmosphere The liquid stream coming out from the separator is then expanded by a valve to reduce the pressure to 250 psia This makes it ready to enter a distillation column in order to separate the extra hydrogen left with the hydrocarbons A typical flowsheet of the ARDS process is shown in Figure Perform a material and energy balance for the ARDS process using UNISIM simulator Solution:  Enter  the   simulation  basis   environment  in  UNISIM  Add  the  components  as  follows:  Thiophene,  n-­‐C30,  n-­‐C20,  n-­‐C10 ,  n-­‐C4,  H2  and  H2S  Select   Peng–Robinson  as  the   fluid  package  Insert  Reaction-­‐1  stoichiometry  and  conversion  and  do  the   same   for  Reaction-­‐2  Enter  simulation   environment  Insert  the   first  unit  for  the  oil   feed  as  shown  in  the   flow  chart  with  compositions,  temperature   and  pressure  as  given  in  Table  2  Continue  inserting   units  as   shown  in  the  flowsheet  The   reactor  is  a   conversion  reactor  The   distillation   column  is   15  trays  with  reflux  ratio  equal   to  1.0  and  full  reflux  The   active   specification  to  run  the   distillation   column  is  a  hydrogen  recovery  of  100%  and  an  n-­‐decane recovery  of  90% 10  Finally,  add  the   recycle  control  unit  to  optimize  the   connections UNISIM  results [...]... suspend  them  in   liquid   oil  Because  each  asphaltene is  surrounded   by  a  number  of  resin  molecules,  the   content  of  resins  in  crude  oils  is  higher  than  that  of  the  asphaltenes 2.2  Products  Composition -­‐ Liquefied   Petroleum  Gas  (LPG) -­‐ Gasoline -­‐ Kerosene -­‐ Jet  Fuel -­‐ Diesel  Fuel -­‐ Fuel Oil  (Residual  Fuel Oil) -­‐ Lube Oil -­‐ Asphalt -­‐ Petroleum... 2.1  Composition   of  Crude  Oils 2.1  Composition   of  Crude  Oils Hydrocarbons: -­‐ Paraffins -­‐ Olefins are  not  naturally   present  in  crude  oils   but  they  are  formed  during   the  conversion   processes -­‐ Naphthenes (cycloalkanes):   Mutli-­‐ring   naphthenes are  present  in  the  heavier   parts  of  the  crude oil -­‐ Aromatics Polynuclear aromatic  compounds  are  found  in...  Crude  Oils Hydrogen  to  carbon  ratios  affect  the  physical  properties  of  crude oil   -­‐ As the hydrogen to carbon ratio decreases, the gravity and boiling point of the hydrocarbon compounds increases -­‐ the  higher  the  hydrogen  to  carbon  ratio  of  the  feedstock,  the  higher  its   value  is  to  a  refinery  because  less  hydrogen  is  required 2.1  Composition   of  Crude  Oils... 2.1  Composition   of  Crude  Oils -­‐ Oxygen  Compounds • less  than  2  wt%   • include   alcohols,   ethers,  carboxylic   acids,   phenolic   compounds,   ketones,  esters  and   anhydrides   • causes  the  crude  to  be  acidic  with   consequent  processing   problems  such  as   corrosion 2.1  Composition   of  Crude  Oils -­‐ Nitrogen  Compounds • Crude  oils  contain  very  low  amounts...  compounds:  pyridines • Non-­‐basic  nitrogen  compounds:  pyrrole types 2.1  Composition   of  Crude  Oils -­‐ Metallic  Compounds • • • • • • • • exist  in  all   crude oil  types   in  very  small  amounts cause  operational  problems  and  contaminate  the  products,  affect  upgrading processes cause  poisoning  to  the  catalysts used  for  hydroprocessing and  cracking   small  amounts...  magnesium   and  calcium  à removed  in  desalting  operations   oil- ­‐soluble  organometallic  compounds:  Zinc,  titanium,  calcium  and  magnesium  appear  in  the  form   of  organometallic  soaps oil- ­‐soluble  compounds:  vanadium,  nickel,  copper  and  iron  àcomplexing with  pyrrole compounds 2.1  Composition   of  Crude  Oils -­‐ Asphaltenes: -­‐ condensed   polynuclear aromatic  layers... and  coke   deposition   during   processing à environmental   problems   2.1  Composition   of  Crude  Oils 2.1  Composition   of  Crude  Oils -­‐ Sulphur Compounds • varies  from  less  than  0.05  to  more  than  10   wt%  (but  generally   falls  in  the  range  1–4   wt%)   • Crude oil  with  less  than  1  wt%  sulphur is   referred  to  as  low  sulphur or  sweet,  and   that  with  more...  of   nitrogen  compounds   • the  more  asphaltic   the oil,  the  higher  its   nitrogen  content   • more  stable  than  sulphur compounds   à harder   to  remove   • be  responsible   for  the  poisoning   of  a  cracking   catalyst,  and  contribute  to  gum  formation   in   finished   products • The  nitrogen   compounds   in  crude  oils  may  be   classified  as  basic  or  non-­‐basic ...  Hydrocarbon   Family   Analysis 2.4.5  Aromatic  Carbon  Content 2.4.6  SARA  Analysis ASTM  testing  grid  for  crude oil  and  petroleum  fractions Unit  3  Modern  Petroleum  Processing   Unit  3  Modern  Petroleum  Processing   3.1  SEPARATION   3.1.1  Distillation 3.1.2  Solvent Refining 3.2  CONVERSION   3.2.1  Thermal  cracking 3.2.2  FCC 3.2.3  Hydrotreating and  hydrocracking 3.3  UPGRADING...  atmospheric  residue  of   any  light  hydrocarbon  and   • To  lower  the  partial  pressure  of  the   hydrocarbon  vapours in  the  flash   zone   àlowering  the  boiling  point  of  the   hydrocarbons   àcausing  more  hydrocarbons  to  boil   and  go  up  the  column  to  be   eventually  condensed  and  withdrawn   as  side  streams   Vacuum  Distillation   -­‐ residue  from  an  atmospheric   distillation