Energy concept for future oil refineries with an emphasis on separation processes

1
Energy concept for future oil refineries with an
emphasis on separation processes

• Antonio Brandão
• Department of Chemical Engineering
• Federal University of Campina Grande
• Campina Grande, Paraiba
• December 2011

2
About this presentation

• Motivation
• Focus on environmental aspects in oil refining is
  not enough (Szklo 2007, DOE 2000).
• Energy-efficient processes in oil refining are
  paramount.
• Need for research in this field is a must.
• Important literature
• U.S. DOE, Energy Bandwidth for Petroleum Refining
  Processes, Office of Energy Efficiency and
  Renewable Energy, Office of Industrial
  Technologies, 2006.
• Szklo, A., Schaeffer, R., Fuel specification,
  energy consumption and CO2 emission in oil
  refineries, Energy 32, 10751092, 2007.
• Focus
• Whats up on the future of energy consumption in
  oil refineries.
• Opportunities Attempt to give directions, not
  specific solutions for particular problems (e.g.,
  impact of sulfur reduction in diesel and/or
  gasoline).
• Looking at the big picture Not restricted to
  separation processes.
• Goal
• Attempting to show what one can expect in terms
  of more energy-efficient refineries in the long
  run.

3
About this presentation

• Lets tear things down

Energy concept Energy efficiency. Keep it
simple!
Energy concept for future refineries.
Directions will be given but problems wont be
solved here!
Splitter
Future Next 20 years??? Nothing futuristic! No
revolution!

• Directions will be given Well, it cannot be
  different since there are lots of alternatives to
  consider. But details wont be discussed here!
• You may try, e.g., Oil Refining Industry -
  Process Flow - Data Sheets.pdf, for specifics.

4
Outline

• A vision for the future
• A simple guide to oil refining
• Energetic issues in an oil refinery
• Thermodynamic analysis and measures to improve
  energy consumption.
• Crude oil distillation (atmospheric and vacuum)
• Fluid catalytic cracking
• Catalytic hydrotreating
• Catalytic reforming
• Alkylation
• Hydrogen generation
• Separation processes
• Recap and future directions
• References

5
A vision for the future

• According to the APIs Technology Vision 2020 A
  Technology Vision for the U.S. Petroleum Refining
  Industry API 2000 report,
• The petroleum industry of the future will be
  environmentally sound, energy-efficient, safe and
  simpler to operate. It will be completely
  automated, operate with minimal inventory, and
  use processes that are fundamentally
  well-understood. Over the long term, it will be
  sustainable, viable, and profitable, with
  complete synergy between refineries and product
  consumers.
• To improve energy and process efficiency, the
  industry will strive to use cost-effective
  technology with lower energy-intensity.
  Refineries will integrate state-of-the-art
  technology (e.g., separations, catalysts, sensors
  and controls, biotechnology) to leapfrog current
  refinery practice and bring efficiency to new
  levels.

6
Outline

• A vision for the future
• A simple guide to oil refining
• Energetic issues in an oil refinery
• Thermodynamic analysis and measures to improve
  energy consumption.
• Crude oil distillation (atmospheric and vacuum)
• Fluid catalytic cracking
• Catalytic hydrotreating
• Catalytic reforming
• Alkylation
• Hydrogen generation
• Separation processes
• Recap and future directions
• References

7
A simple guide to oil refining

• According to the North American Industry
  Classification System (NAICS) DOE 2006,
  petroleum refineries are defined as
• Establishments primarily engaged in refining
  crude petroleum into refined petroleum.

Picture of the oil refinery of the future, if the
oil consumption maintains its forever growing
pace Actually, this is a 1876 oil refinery in
California.
8
A simple guide to oil refining Exxon 2005
9
A simple guide to oil refining

• In short
• Everything is upgraded to valuable products More
  fuel!
• Over 43 of production is gasoline.
• C.a. 80 is converted to fuel.
• It is a huge, extremely complex process
  facility!!!
• Lots of reactions and separations to add value to
  the products.
• Many opportunities for energy savings.

10
Outline

• A vision for the future
• A simple guide to oil refining
• Energetic issues in an oil refinery
• Thermodynamic analysis and measures to improve
  energy consumption.
• Crude oil distillation (atmospheric and vacuum)
• Fluid catalytic cracking
• Catalytic hydrotreating
• Catalytic reforming
• Alkylation
• Hydrogen generation
• Separation processes
• Recap and future directions
• References

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Energetic issues in an oil refinery (DOE 2000,
Pellegrino 2005)

• Refinery gas petroleum coke other oil-based
  by-products accounts for 65 of the energy
  sources in an oil refinery.
• 38 of the energy sources in an oil refinery are
  used to produce non-fuel products like lubricant
  oils, wax, asphalt, and petrochemical feedstocks.
• Oil refineries generate large amounts of
  electricity on-site. In the U.S., over 40 (1994)
  of electricity in refineries are on-site
  generated.
• The cost of energy for heat and power accounts
  for c.a. 40 of the operating costs in a
  refinery!!!

12
Energetic issues in an oil refinery DOE 2007
13
Energetic issues in an oil refinery DOE 1998

• According to the NAICS (The North American
  Industry Classification System), petroleum
  refineries consumed 3.1 quadrillion Btu (fuel use
  alone) in 2002, almost 20 of the fuel energy
  consumed by the U.S..
• From the Table, c.a. 31 is consumed in two
  distillation processes.
• As expected, hydrotreating is also very high, 15
  alone.
• Hydrogen generation is yet another high energy
  consumption process.
• Large amounts of energy are consumed as fuel,
  while the rest is basically steam.
• The bullets represent units prone to be
  optimized energetically as they represent
  approx. 86 of the energy consumed by the
  refining process.
• We will focus on these units.

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Energetic issues in an oil refinery Worrell 2005
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Energetic issues in an oil refinery
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Energetic issues in an oil refinery DOE 2000

• Future characteristics of oil refineries in terms
  of energy use
• Energy use is optimized throughout the refinery
  complex (plantwide energy optimization).
• Energy efficiency and process control are
  integrated (plantwide process control).
• Fouling of heat exchangers is essentially
  eliminated.
• Innovative heat exchangers are in place (all
  helical, vertical, no baffles)
• Use of cogeneration in refineries is optimized,
  and refineries are power producers.
• Use of very energy-intensive processes (e.g.,
  distillation, furnaces) is mitigated.
• Source of heat loss (e.g., in pipes) are easily
  identified through monitoring.
• How?
• Identify entirely new technologies.
• Upgrade existing inefficient technologies.

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Energetic issues in an oil refinery DOE 2000

• Replacing the conventional energy-intensive
  separation processes has a tremendous impact on
  energy consumption.
• Waste recovery in the short term.
• Fouling mitigation and new refining processes in
  the mid and long terms.
• Membrane is the first step.
• Catalytic distillation is in the mid run.
• Long run distillation beyond membrane.
• Pelegrino 1999 say the target is 15-20 energy
  reduction for U.S. refineries.

Distillation roadmap
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Outline

• A vision for the future
• A simple guide to oil refining
• Energetic issues in an oil refinery
• Thermodynamic analysis and measures to improve
  energy consumption.
• Crude oil distillation (atmospheric and vacuum)
• Fluid catalytic cracking
• Catalytic hydrotreating
• Catalytic reforming
• Alkylation
• Hydrogen generation
• Separation processes
• Recap and future directions
• References

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Thermodynamic analysis DOE 2006

• Remember the 6 processes with the largest energy
  consumption?
• A thermodynamic analysis of these 6 processes is
  performed here.
• Three measures are defined
• TW Theoretical Work The least amount of energy
  that a process would require under ideal
  conditions. E.g., for separation processes it is
  basically the sensible and latent heat of each
  component in the mixture considered as an ideal
  solution, and for reaction systems the heat of
  reaction under 100 selectivity at equilibrium
  conditions.
• CW Current Work Energy consumed under actual
  plant conditions where energy losses from
  inefficient or outdated equipment and process
  design, poor heat integration, and poor
  conversion and selectivities, among other factors
  are considered. Source USA DOE.
• PW Practical Work Minimum energy required to
  run the process in real-world, non-standard
  conditions by applying cutting edge technologies
  still on the drawing board. The savings are then
  deducted from the CW requirement.
• Therefore, the maximum potential for energy
  savings can be quantified by

PI (Potential Improvement) CW (Current Work)
PW (Practical Work)
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Crude oil distillation (atmospheric and vacuum)

• Atmospheric distillation
• It is the heart of the refinery.
• It produces a range of products, from LPG to
  heavy crude residue.
• High temperature (bottom 600oC), low pressure
  (near atmospheric) process.
• Vacuum distillation
• It has heavy crude (high boiling point) as
  feedstock.
• It must then be conducted at vacuum conditions.
• It produces light and heavy gas oil and asphalt
  (or resid).
• These products are upgraded.

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Crude oil distillation (atmospheric and vacuum)
22
Crude oil distillation (atmospheric and vacuum)

• Atmospheric distillation energetic assessment
  DOE 2006
• Theoretical work 22 x 103 Btu/bbl feed
• Current work 114 x 103 Btu/bbl feed
• Practical work 50 x 103 Btu/bbl feed
• Potential improvement 64 x 103 Btu/bbl feed

Note Electricity losses incurs during the
generation, transmission, and distribution of
electricity.
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Crude oil distillation (atmospheric and vacuum)

• Atmospheric distillation energetic assessment
  DOE 2006
• Theoretical work 22 x 103 Btu/bbl feed
• Current work 114 x 103 Btu/bbl feed
• Practical work 50 x 103 Btu/bbl feed
• Potential improvement 64 x 103 Btu/bbl feed
• The potential improvement can be achieved by
  (Gadalla 2003a, Gadalla 2003b, ANL 1999,
  TDGI 2001, Liporace 2005, Seo 2000, Rivero
  2004, Yeap 2005, Hovd 1997, Sharma 1999)
• Control of fouling in the crude preheat train and
  fired heater.
• Improved heat integration between the atmospheric
  and vacuum towers.
• Improved tray design and heat integration between
  trays, and optimization of the number of trays
  and operating conditions for improved
  vapor-liquid contact and higher throughput.
• Enhanced cooling to lower overhead condenser
  cooling water from 75 to 50F.
• Implementation of advanced control or revamp of
  the control structure with simple plantwide
  control.

24
Crude oil distillation (atmospheric and vacuum)

• Vacuum distillation energetic assessment DOE
  2006
• Theoretical work 46 x 103 Btu/bbl feed
• Current work 92 x 103 Btu/bbl feed
• Practical work 54 x 103 Btu/bbl feed
• Potential improvement 38 x 103 Btu/bbl feed

25
Crude oil distillation (atmospheric and vacuum)

• Vacuum distillation energetic assessment DOE
  2006
• Theoretical work 46 x 103 Btu/bbl feed
• Current work 92 x 103 Btu/bbl feed
• Practical work 54 x 103 Btu/bbl feed
• Potential improvement 38 x 103 Btu/bbl feed
• The potential improvement can be achieved by
  (Gadalla 2003a, Gadalla 2003b, ANL 1999,
  TDGI 2001, Sharma 1999, Liporace 2005, Seo
  2000, Rivero 2004, Yeap 2005)
• Control of fouling in the fired heater.
• Improved heat integration between the atmospheric
  and vacuum towers.
• Improved tray design and heat integration between
  trays, and optimization of the number of trays
  and operating conditions for improved
  vapor-liquid contact and higher throughput.
• Enhanced cooling to lower overhead condenser
  cooling water from 75F to 50F.
• Implementation of advanced control or revamp of
  the control structure with simple plantwide
  control.

26
Fluid catalytic cracking

• Objective Convert heavy oils into more valuable
  gasoline and lighter products.
• Feedstocks are light and heavy gas oil from
  atmospheric or vacuum distillation, coking, and
  deasphalting operations.

High temperature, catalytic cracking reactions
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Fluid catalytic cracking
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Fluid catalytic cracking

• Energetic assessment DOE 2006
• Theoretical work 40 x 103 Btu/bbl feed
• Current work 209 x 103 Btu/bbl feed
• Practical work 132 x 103 Btu/bbl feed
• Potential improvement 77 x 103 Btu/bbl feed

29
Fluid catalytic cracking

• Energetic assessment DOE 2006
• Theoretical work 40 x 103 Btu/bbl feed
• Current work 209 x 103 Btu/bbl feed
• Practical work 132 x 103 Btu/bbl feed
• Potential improvement 77 x 103 Btu/bbl feed
• The potential improvement can be achieved by
  (Linhoff 2002, ANL 1999)
• Addition of a power recovery turbine.
• Conversion of condensing turbine drive to
  electric motor drive (wet gas compressor).
• Improved heat integration, pinch analysis.
• Minimization of other miscellaneous losses.
• Extra Implementation of advanced control or
  revamp of the control structure with simple
  plantwide control.

30
Catalytic hydrotreating

• Objective Remove sulfur, nitrogen, and metals
  and upgrade heavy olefinic feed by saturation
  with hydrogen to produce paraffins.
• It commonly appears in multiple locations in a
  refinery (5 or more of these units).
• They are usually placed upstream of units where
  catalyst deactivation may occur from feed
  impurities.
• Typically we can distinguish Naphtha
  hydrotreater, kerosene hydrotreater, and gas oil
  hydrotreater.
• Main reactions

31
Catalytic hydrotreating
32
Catalytic hydrotreating

• Energetic assessment DOE 2006
• Theoretical work 30 x 103 Btu/bbl feed
• Current work 88 x 103 Btu/bbl feed
• Practical work 55 x 103 Btu/bbl feed
• Potential improvement 33 x 103 Btu/bbl feed

33
Catalytic hydrotreating

• Energetic assessment DOE 2006
• Theoretical work 30 x 103 Btu/bbl feed
• Current work 88 x 103 Btu/bbl feed
• Practical work 55 x 103 Btu/bbl feed
• Potential improvement 33 x 103 Btu/bbl feed
• The potential improvement can be achieved by
  (ANL 1999, Gary 2001, Linhoff 2002,
  Liebmann 1998)
• Improved pre-heater performance.
• Improved catalyst.
• Improved heat integration, pinch analysis.
• Minimization of other miscellaneous losses.
• Extra Implementation of advanced control or
  revamp of the control structure with simple
  plantwide control.

34
Catalytic reforming

• Objective Convert naphthas and heavy
  straight-run gasoline into high-octane gasoline
  blending components, as well as hydrogen
  generation.
• It essentially restructures hydrocarbon molecules
  to increase the octane of motor gasoline.
• Main reactions
• Dehydrogenation of naphthenes to aromatics
• Methylcyclohexane ? Toluene 3H2
• Methylcyclopentane ? Cyclohexane ? Benzene 3H2
• Dehydrocyclization of paraffins to aromatics
• n-Heptane ? Toluene 4H2
• Isomerization
• n-Hexane ? Isohexane
• Methylcyclopentane ? Cyclohexane
• Hydrocracking
• n-Decane ? Isohexane nButane

35
Catalytic reforming
36
Catalytic reforming

• Energetic assessment DOE 2006
• Theoretical work 79 x 103 Btu/bbl feed
• Current work 269 x 103 Btu/bbl feed
• Practical work 203 x 103 Btu/bbl feed
• Potential improvement 66 x 103 Btu/bbl feed

37
Catalytic reforming

• Energetic assessment DOE 2006
• Theoretical work 79 x 103 Btu/bbl feed
• Current work 269 x 103 Btu/bbl feed
• Practical work 203 x 103 Btu/bbl feed
• Potential improvement 66 x 103 Btu/bbl feed
• The potential improvement can be achieved by
  (ANL 1999, Gary 2001, Packinox 2003)
• Improved feed and interstage process heater
  performance (e.g., improved convection section
  heat recovery).
• Replace horizontal feed/effluent heat exchangers
  with vertical plate and frame exchanger.
• Improved equipment efficiency (e.g., recycle and
  net gas compressor, reactor product air cooler).
• Additional process cooling to improve light ends
  recovery (vapor compression vs. ammonia
  absorption).
• Minimization of other miscellaneous losses.
• Extra Implementation of advanced control or
  revamp of the control structure with simple
  plantwide control.

38
Alkylation

• Objective Produce branched paraffins that are
  used as blending components in fuels to boost
  octane levels without increasing the fuel
  volatility.
• There are two alkylation processes sulfuric
  acid-based and hydrofluoric acid-based.
• Both are low-temperature, low-pressure,
  liquid-phase catalyst reactions.
• Main reaction

39
Alkylation (H2SO4 process)
40
Alkylation (H2SO4 process)

• Energetic assessment DOE 2006
• Theoretical work -58 x 103 Btu/bbl feed
• Current work 335 x 103 Btu/bbl feed
• Practical work 156 x 103 Btu/bbl feed
• Potential improvement 179 x 103 Btu/bbl feed

41
Alkylation (H2SO4 process)

• Energetic assessment DOE 2006
• Theoretical work -58 x 103 Btu/bbl feed
• Current work 335 x 103 Btu/bbl feed
• Practical work 156 x 103 Btu/bbl feed
• Potential improvement 179 x 103 Btu/bbl feed
• The potential improvement can be achieved by
  (Gadalla 2003a, TDGI 2001, DOE 2006,
  Schultz 2002)
• Improved compressor efficiency, from 25 to 50.
• Improved heat integration, pinch analysis.
• Use of a dividing wall column design or other
  advanced separation technology.
• Upgraded control system revamp of the control
  structure with simple plantwide control.

42
Hydrogen production

• Objective Generate (complement) H2 for
  hydrocracking, hydrotreating, hydroconversion,
  and hydrofinishing process throughout the
  refinery.
• Sources for hydrogen in a refinery are basically
  by-products from catalytic reforming, recovery
  from H2 rich off-gases, and the hydrogen plant
  production.
• The principal process for converting hydrocarbons
  into hydrogen is catalytic steam reforming.
• The main reactions are
• CH4 H2O ? CO 3H2 (-?Ho298 -206 kJ/mol)
• CO H2O ? CO2 H2 (-?Ho298 41 kJ/mol)
• CnHm H2O ? nCO (m2n)/2H2 (-?Ho298 -1109
  kJ/mol for nC7H16)
• The main reaction, methane conversion, must be
  carried out at high temperature, high steam to
  carbon ratio, and low pressure to achieve maximum
  conversion.

43
Hydrogen production
44
Hydrogen production

• Energetic assessment Rostrup-Nielsen 2005
• Theoretical work 67 x 103 Btu/bbl feed
• Current work 111 x 103 Btu/bbl feed
• Practical work 71 x 103 Btu/bbl feed
• Potential improvement 30 x 103 Btu/bbl feed
• The potential improvement can be achieved by
  (Rostrup-Nielsen 2005)
• Higher (optimized) reforming temperature (gt 900
  oC) and lower (optimized) steam to carbon ratio
  (lt 2.0).
• Reformer design that does not export steam.
• Catalysts to reduce carbon formation.
• Membrane reforming technology with CO2
  sequestration.
• Extra Implementation of advanced control or
  revamp of the control structure with simple
  plantwide control.

45
Summary
Process TW PW CW PI CW - PW PI PI/CW()
103 Btu/bbl feed 103 Btu/bbl feed 103 Btu/bbl feed 103 Btu/bbl feed 103 Btu/bbl feed
1. Atmospheric distillation 22 50 114 64 56
2. Alkylation H2SO4 -58 156 335 179 53
3. Vacuum distillation 46 54 92 38 41
4. Alkylation HF -58 152 255 103 40
5. Catalytic hydrotreating 30 55 88 33 38
6. Fluid catalytic cracking 40 132 209 77 36
7. Hydrogen production 67 71 111 30 27
8. Catalytic reforming 79 203 269 66 24

• The overall savings, including capacities, can
  reach up to 42.
• Atmospheric vacuum distillations have the
  largest potential for savings.
• Followed by alkylation and catalytic treatments.
• Note that separation sections are also included
  in the conversion processes.
• As a general potential improvement in the short
  term, I particularly would also include
  assessment of the control structure design of the
  entire refinery.

46
Summary

• Remember this picture?
• Now have a look at the figures on the right.
• Gasoline requires the largest amount of energy to
  be produced. While gasoline makes up 43 by
  volume of refinery product output, its production
  consumes 62 of the refinery energy requirement.
• Distillate fuel oil is the next most
  energy-intensive product stream, consuming 17 of
  refinery energy requirement.
• The remaining 21 is distributed fairly evenly
  between the other product streams.

TBtu/year
1,305 62.1
355 16.9
76 3.6
113 5.4
77 3.7
37 1.8
51 2.4
75 3.6
12 0.6
47
Outline

• A vision for the future
• A simple guide to oil refining
• Energetic issues in an oil refinery
• Thermodynamic analysis and measures to improve
  energy consumption.
• Crude oil distillation (atmospheric and vacuum)
• Fluid catalytic cracking
• Catalytic hydrotreating
• Catalytic reforming
• Alkylation
• Hydrogen generation
• Separation processes
• Recap and future directions
• References

48
Separation processes

• The majority of the available literature is
  related to the issue concerning distillation, and
  they are heavily concentrated in the atmospheric
  and vacuum columns. I bet you know the reason!
• Future solutions for improving energy efficiency
  in separation processes in oil refineries are
  basically related to
• Membrane technology.
• Fouling mitigation.
• Optimization and advanced process control.
• Heat integration.
• Design of efficient separation systems.
• What follows are mostly on the drawing board,
  i.e., no real-world implementation.

49
Separation processes

• Membrane technology (still an on going
  development)
• Wauquier 2000 discusses that membrane
  technology is still an infant in the world of
  grown-up inefficient processes in the oil
  industry. Its main application is in
  hydrodesulfurization processes in catalytic
  hydrotreating units, replacing existing
  separation processes with energy savings up to
  20.
• Nevertheless, Goulda 2001 and White 2000
  claimed a fuel reduction of 36,000 bbl/year (or
  20 w.r.t. the conventional process) by adding a
  membrane unit in the dewaxing unit to recover
  part of the solvent stream. The membrane is
  selective to the solvent from the solvent/oil/wax
  mix.
• According to Szklo 2007, further research is
  needed to develop appropriate membrane materials
  that can withstand the harsh conditions in
  petroleum refining processes.

50
Separation processes

• Fouling mitigation (basically monitoring)
• Panchal 2000 presented a performance monitoring
  via an Excel spreadsheet of the preheat train
  for a crude distillation unit. The authors claim
  that by using their technique the energy loss in
  a period of 2 years can be reduced by almost 60.
• Nasr 2006 proposed a model of crude oil fouling
  in preheat exchangers with the aim of better
  controlling fouling formation. In contrast with
  other models, the one proposed by the authors
  consider the mechanisms of formation and natural
  removal.
• Yeap 2005 presented the application of existing
  fouling models to maximize heat recovery in the
  preheat train of the crude oil distillation. The
  authors conclusion was that designing for
  maximum heat recovery results in a less efficient
  system over time due to fouling effects.
• However, Szklo 2007 states that the very
  complex mechanisms which lead to fouling are
  still not properly understood to the extent they
  can be safely used for fouling mitigation
  techniques (anti-fouling agents and coatings).

51
Separation processes

• Advanced process control and optimization
  (essentially modeling)
• Domijan 2005 optimized a crude distillation
  unit by using a model that, according to the
  authors, has some advantages over commercial ones
  since it is adapted to real plant conditions, it
  is open source as well as flexible and fast.
  Moreover, it can also identify fouling level and
  be applied for planning shutdowns and maintenance
  stops. They claimed they found an optimal
  solution that saves up to 3.2 of energy
  consumption vis-à-vis actual operating
  conditions.
• Seo 2000 considered the optimal design of the
  crude distillation unit (atmospheric, vacuum, and
  naphtha stabilizer) by optimizing feed locations,
  heat duties of pumparounds and operating
  conditions of the preheat train. They use a MINLP
  framework. They claim the energy recovery in
  pumparounds and preheat train could save up to 20
  million kcal/h.
• Hovd 1997 proposed the implementation of MPC in
  a crude oil distillation. They used the MPC
  package (D-MPC) of Fantoft Prosess and a linear
  model of the process obtained using
  first-principle model equations and laboratory
  data. They implemented the MPC strategy in a
  refinery in Sweden and reported a reduction in
  energy consumption equivalent to USD20,000/year
  for a project investment of USD250,000.
• Gadalla 2003b performed a very simple
  optimization of existing heat-integrated
  distillation systems for crude oil units where
  the column (with fixed configuration) and the
  associated heat exchanger network are considered
  simultaneously. Only one design (retrofit)
  variable is assumed area of the HEN. They
  claimed savings up to 25 over the base case.

52
Separation processes

• Heat integration
• Gadalla 2006 optimized an existing crude
  distillation column where a gas turbine/generator
  is integrated with the preheat furnace. They
  claim energy reductions of up to 21. The idea
  was then to maximize the energy generated in the
  gas turbine by adjusting the temperature of the
  feed, reflux ratio, steam flow rates, temperature
  difference of each pumparound, and the flow rate
  of the liquid through each pumparound.
• Gadalla 2005 studied the design of an
  internally heat-integrated distillation column
  for separating an equimolar propylene-propane
  mixture where the 57 stages of the stripping
  column are heated by the first 57 stages of the
  rectification column. They claim that by
  increasing the heat transfer rate per stage,
  energy savings can reach up to 100 of reboiler
  duties. For this, the compressor power would
  increase only 15 w.r.t. the base HIDiC case.
• By applying pinch analysis, Plesu 2003 propose
  to thermally couple crude distillation units and
  delayed coking units through the utility system.
  They basically proposed to send the vacuum
  bottoms to the delayed coking unit at a higher
  thermal load and use this artifice to generate
  part of the steam needed in the crude
  distillation unit. They do not report energy
  saving figures.

53
Separation processes

• Heat integration
• Liebmann 1998 proposed a systematic algorithm
  based on pinch analysis that lends to automation
  of the design procedure of crude oil distillation
  units where the column, the heat exchanger
  network, and their simultaneous interactions are
  considered together. Modifications that further
  increase the efficiency of the process are
  installation of reboilers rather than stripping
  stream and the thermal coupling of column
  sections. They claimed that units conceived by
  this method can save up to 20 energy w.r.t. the
  base case.
• Szklo 2007 states that heat integration and
  waste heat recovery appears as one of the main
  options for saving fuel in the short to mid terms.

54
Separation processes

• Design of efficient separation systems
• Szklo 2007 discussed the use of catalytic
  distillation (CD) as an indeed very promise
  alternative to hydrotreating units, namely to FCC
  gasoline. The idea is to fractionate the gasoline
  by distillation, which yields several gasoline
  fractions, and then treat each fraction for
  sulfur according to their prevailing sulfur
  compound reactivities, all in the same unit.
  Lighter fraction are treated more severely while
  the heavier ones undergo desulfurization at
  higher temperatures at the bottom of the CD
  column. The authors claimed that up to 62 of
  energy can be saved w.r.t. conventional HDS
  processes.
• Szklo 2007 also discussed the application of
  biodesulfurization in replacement of conventional
  HDS with energy savings of up to 80. However,
  the technology is still at its dawn, and the main
  barriers are the understanding of biological
  mechanisms of biocatalysts and the development of
  efficient two-phase biodesulfurization systems.
• Schultz 2002 defended the thesis that
  dividing-wall columns (DWC) can save up to 30 in
  energy costs. In this technology, remixing of
  components towards the bottom or top of a direct
  sequenced train which causes thermal inefficiency
  is mitigated by cutting the product at their
  maximum compositions. However, Szklo 2007
  emphasized the need for further development of
  DWC for major distillation processes in the oil
  refining industry.

55
Separation processes

• Design of efficient separation systems
• According to Pellegrino 1999 a potentially
  attractive refining process modification is to
  input the crude directly into controlled thermal
  cracking units, thereby bypassing CDU. The idea
  is to crack large hydrocarbon molecules (e.g.,
  large asphaltene-type molecules) into smaller
  ones. They reported a reduction in energy
  consumption of 23 in addition to the fact that
  up to 80 of the energy generated in the unit can
  be recovered as reusable energy.
• EIPCCB 2001 discussed the use of a radical
  revamp that encompasses atmospheric and vacuum
  distillation, gasoline fractionation, naphtha
  stabilizer and gas plant in one unit progressive
  distillation. It consists of a fairly complex set
  of separation steps and extensively uses pinch
  technology to minimize heat supplied by external
  means. The savings can reach up to 30 on total
  energy consumption for these units.

56
Outline

• A vision for the future
• A simple guide to oil refining
• Energetic issues in an oil refinery
• Thermodynamic analysis and measures to improve
  energy consumption.
• Crude oil distillation (atmospheric and vacuum)
• Fluid catalytic cracking
• Catalytic hydrotreating
• Catalytic reforming
• Alkylation
• Hydrogen generation
• Separation processes
• Recap and future directions
• References

57
Recap and future directions

• It seems there is no radical revolution going on
  in the oil refining industry so to handle energy
  efficiency. Instead, the 2020 Vision report API
  2000 lists
• Reduction of fouling in heat exchangers is a
  definite priority.
• Improved convection in furnaces is necessary.
• Cogeneration needs to be optimized.
• Use of conventional distillation should be
  minimized. Try membrane and catalytic
  distillation.
• Lets not forget research in catalysis.
• Comprehensive mathematical process models in oil
  refinery are a must for short term results DOE
  2000.
• Process optimization is definitely in the oil
  refinery agenda Domijan 2005.
• Investments in RD represent one way to help
  drive the industry toward a higher level of
  energy efficiency. However, implementation is
  still at its very infancy as there are still
  technological/psicological barriers.
• Accordingly, separation processes need to be
  updated. However, one should look at the big
  picture.
• Needless to say, energy reduction ? CO2 emission
  reduction!

58
Recap and future directions

• Wanna a hint to decide your PhD project? Energy
  efficiency program for future oil refineries.
  Ease, 5 (huge) PhD projects
• Fouling modeling and elucidation of its
  mechanism in the crude distillation unit
  (atmospheric and vacuum columns and respective
  HEN) as well as development of anti-fouling
  chemicals that little affects refining products
  quality.
• Membrane theres still a technological barrier
  with the current membranes. More research is
  needed to extend the application to other
  separation units throughout the refinery.
• Advanced process control and optimization
  investigation of plantwide control and
  optimization (I only found information about
  these issues applied to individual units).
• Check also Hydrocarbon Processing Advanced
  Process Control and Information Systems 2005.pdf.
• Heat integration investigation of more plantwide
  heat integration opportunities by pinch or exergy
  analysis.
• Distillation design more on reactive (catalytic)
  distillation and dividing-wall technology applied
  to energy-intensive units (FCC, alkylation,
  hydrotreating, reforming, and crude distillation
  units). Especially, biodesulfurization.

59
Outline

• A vision for the future
• A simple guide to oil refining
• Energetic issues in an oil refinery
• Thermodynamic analysis and measures to improve
  energy consumption.
• Crude oil distillation (atmospheric and vacuum)
• Fluid catalytic cracking
• Catalytic hydrotreating
• Catalytic reforming
• Alkylation
• Hydrogen generation
• Separation processes
• Recap and future directions
• References

60
References

• Gadalla 2003a Gadalla, M., Jobson, M., and
  Smith, R., Increase Capacity and Decrease Energy
  for Existing Refinery Distillation Columns,
  Chemical Engineering Progress, April 2003, p. 44.
• ANL 1999 - Petrick, M. and Pellegrino, J., The
  Potential for Reducing Energy Utilization in the
  Refining Industry, Argonne National Laboratory,
  ANL/ESD/TM-158, August 1999.
• Linhoff 2002 - Linhoff March, a division of KBC
  Process Technology Ltd., The Methodology and
  Benefits of Total Site Pinch Analysis, 2002,
  http//www.linnhoffmarch.com/resources/technical.h
  tml.
• Gary 2001 - Gary, J.H., and Handwerk, G.E.,
  Petroleum Refining Technology and Economics, 4th
  Edition, Marcel Dekker, Inc., New York, NY.,
  2001.
• Packinox 2003 - Reverdy, F., Packinox, Inc.,
  High-Efficiency Plate and Frame Heat Exchangers,
  presented at the 2003 Texas Technology Showcase,
  Houston, Texas, March 2003.
• Schultz 2002 - Schultz, M.A., Stewart, D.G.,
  Harris, J.M., Rosenblum, S.P., Shakur, M.S., and
  OBrien, D.E., Reduce Costs with Dividing-Wall
  Columns, Chemical Engineering Progress, p. 64,
  May 2002.
• TDGI 2001 - The Distillation Group, Inc.,
  Distillation Energy Savings Improvements with
  Capital Investments (Section 4), 2001,
  http//www.distillationgroup.com/distillation/H003
  /H003_04.htm.
• Liporace 2005 Liporace, F. S. and Oliveira,
  S. G., Real-time fouling diagnosis and heat
  exchanger performance, Petrobrás, Internal
  communication, 2005.
• Exxon 2005 ExxonMobil, A simple guide to oil
  refining, 2005, http//www.exxonmobil.com/Europe-E
  nglish/Files/Simple_Guide_to_oil_refining.pdf

61
References

• DOE 1998 - U.S. Department of Energy, Energy
  and Environmental Profile of the U.S. Petroleum
  Refining Industry, Office of Energy Efficiency
  and Renewable Energy, Office of Industrial
  Technologies, 1998.
• API 2000 - American Petroleum Institute,
  Technology Vision 2020 A Technology Vision for
  the U.S. Petroleum Refining Industry, October
  1999.
• Pellegrino 2005 - Pellegrino, J. and Carole, T.
  M., Impacts of Condition Assessment on Energy
  Use Selected Applications in Chemicals
  Processing and Petroleum Refining, U.S.
  Department of Energy, Industrial Technologies
  Program, 2005.
• Seo 2000 Seo, J. W., Oh, M., and Lee, T. H.,
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  Chem. Eng. Technol. 23 , p. 2, 2000.
• Sharma 1999 Sharma, R., Jindal, A.,
  Mandawala, D., and Jana, S. K., Design/Retrofit
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• Al-Qahtani 2006 - Al-Qahtani, A. H., Al-Juhani,
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  AIChE Annual Meeting, San Francisco, Nov 12-17,
  2006.
• Kosobokova 2001 Kosobokova, E. M. and
  Berezinets, P. A., Developing an energy-saving at
  oil refineries, Chemistry and Technology of Fuels
  and Oils, Vol. 37, No. 1, 2001.
• DOE 2000 U.S. Department of Energy,
  Technology Roadmap for the Petroleum Industry,
  Office of Energy Efficiency and Renewable Energy,
  Office of Industrial Technologies, 2000.
• Liebmann 1998 Liebmann, K., Dhole, V. R., and
  Jobson, M., Integrated design of a conventional
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• Gadalla 2003b Gadalla, M., Jobson, M., and
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• Rivero 2004 Rivero, R., Rendón, C., Gallegos,
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• Szklo 2007 Szklo, A., Schaeffer, R., Fuel
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• Goulda 2001 Goulda, R. M., White, L. S.,
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• DOE 2006 - U.S. Department of Energy, Energy
  Bandwidth for Petroleum Refining Processes,
  Office of Energy Efficiency and Renewable Energy,
  Office of Industrial Technologies, 2006.
• Al-Muslim 2005 - Al-Muslim, H. and Dincer, I.,
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• Hovd 1997 Hovd, M., Michaelsent, R., Montin,
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