This presentation is a talk given at the 14 November Philadelphia area AIChE meeting. Chemical engineers, especially those in the US, are increasingly being asked to develop incremental increases in plant capacity, say up to 20%. Many plants are now running at maximum capacity, yet tight capital funding and requirements for short payback periods make it difficult to have large investment for new, grassroots facilities. In some cases, engineers need to meet demand increments much less than the capacity of a new plant, while further demand growth is uncertain. The manufacturer must then choose the appropriate capacity increment, instead of overdesigning Debottlenecking projects are undertaken to deliver these capacity increases, by implementing select changes to specific parts of a plant to relieve restrictions. In this session, we will discuss tools and analyses for assessing the process bottlenecks. We will address means of debottlenecking numerous unit operations, while listing points often forgotten in such projects. Finally we will discuss how debottlenecking projects are different from conventional grass roots projects, while treating the practical aspects of how to manage such projects. A list of references is included for further, deeper study. Many of the facts and figures presented in the talk were taken from these references. Key words: capacity, debottlenecking, process engineering, chemical projects optimization, asset utilization, theory of constraints, TOC, revamp, distillation, fouling, throughput, practical

1. CHEMICAL PROCESS
DEBOTTLENECKING
AICHE PHILADELPHIA 14 NOVEMBER 2016
CONTENT REFLECTS MY OWN VIEWS, NOT THOSE OF MY
EMPLOYER, ARKEMA

2. OUTLINE
 DEBOTTLENECK BACKGROUND
 ASSESSMENTS– where’s your problem?
 CURRENT PRODUCTION LOSSES
 CURRENT VS FUTURE UNIT CAPACITIES
 CURRENT PROCESS CAN BE SIMPLIFIED?
 DEBOTTLENECK TRICKS AND TRAPS
 SOLUTIONS – INCREASE EQUIPMENT CAPACITY
 INCREASE EQUIPMENT CAPACITY
 PROCESS SIMPLIFICATION
 Out of scope: intensification, new technologies, advanced
control
 PROJECT MANAGEMENT FOR DEBOTTLENECK (REVAMP)
PROJECTS
2

3. OUTLINE
 DEBOTTLENECK BACKGROUND
 ASSESSMENTS - where’s your problem?
 CURRENT PRODUCTION LOSSES
 CURRENT VS FUTURE UNIT CAPACITIES
 TRICKS AND TRAPS
 SOLUTIONS
 INCREASE EQUIPMENT CAPACITY
 PROCESS SIMPLIFICATION
 PROJECT MANAGEMENT FOR DEBOTTLENECK
(REVAMP) PROJECTS
3

4. ECONOMIC AND BUSINESS CLIMATE
SUPPORT DEBOTTLENECKING.
 Plants are running maxed out
 Business capacity demands can be incremental,
uncertain or insufficient to justify new plant.
 Increased competition and modest market
growth.
 Tight economic times, especially post- recession,
make big spending difficult.
 Smaller-capacity plants not economical.
4

5. 30-YEAR OLD WISDOM
 “Get more from what we have,” by upgrading
existing facilities instead of building new
 Still true after 30 years! L. Cabano, ChemE
Progress (1987)“Retrofit Projects – the ultimate
management challenge”
5

6. Background debottleneck.
 Debottleneck =improvements to specific parts of a
plant to increase production by relieving limitations.
 Debottlenecking is playing “Moneyball” – Get more
production with smart data and experience, not
necessarily by spending a lot or “buying a new one.”
 Limitations to overcome. Define your problem.
1. Production Losses
2. Process capacity
6

7. OUTLINE
 DEBOTTLENECK BACKGROUND
 ASSESSMENTS - where’s your problem?
 CURRENT PRODUCTION LOSSES
 CURRENT VS FUTURE UNIT CAPACITIES
 TRICKS AND TRAPS
 SOLUTIONS
 INCREASE EQUIPMENT CAPACITY
 PROCESS SIMPLIFICATION
 PROJECT MANAGEMENT FOR DEBOTTLENECK
(REVAMP) PROJECTS
7

8. Know your current production
limitations?
 Define your real problem. How can you really get more
production?
 Eliminate Losses (Opportunities)
 Planned downtime
 Reliability of units
 Availability of resources – internal and external
 Performance - how closely and frequently we run relative
to the Instantaneous, sustainable process capacity
 Quality losses
 Transitions
 Increase instantaneous capacity
8

9. OEE -operational equipment
effectiveness (Williamson 2006)
 A 6-Sigma and TPM (total productive maintenance) concept.
Variants are TEEP (Total Effective Equipment Performance) OAU
(operational asset utilization)
9
Can do with “pounds lost”,
instead of ”time lost.”

10. OEE Definitions
 OEE is a “batting average” comprised of component batting
averages.
 OEE % :
Availability % x Performance efficiency % x Quality rate %
 Availability:
(Actual operating time ÷ Gross available time) x 100%
 Performance efficiency:
(Actual production rate ÷ Design production rate) x 100%
 Quality rate:
((Total produced – Off-spec) ÷ Total produced)) x 100 %
 Can add other “batting averages” for transitions
10

11. Pareto your losses determine
where improvements are needed
11
16.0
5.0
3.0
1.0
0.0
5.0
4
3
1 1
0
2
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
Equipment-
Extruder/Drive
System
Equipment-
Feeders
Process
Interuption
Equipment-
ScreenPack
Equipment-
Utilities
Other
LOSSES(hours)
EXTRUSION LINE MAIN AVAILABILITY LOSSES
Hours
Incidents

12. OUTLINE
 DEBOTTLENECK BACKGROUND
 ASSESSMENTS - where’s your problem?
 CURRENT PRODUCTION LOSSES
 CURRENT VS FUTURE UNIT CAPACITIES
 TRICKS AND TRAPS
 SOLUTIONS – INCREASE EQUIPMENT CAPACITY
 PROJECT MANAGEMENT FOR DEBOTTLENECK
(REVAMP) PROJECTS
12

13. ASSESS CAPACITY BOTTLENECKS –
BATCH PROCESSES
 Talk to the operators for clues
 Theory of Constraints (“The Goal,” by Goldratt.)
 WIP (work in process) accumulates just ahead of the
bottleneck unit.
 WIP is scarce downstream of the bottleneck.
 Time studies on existing process phases. Collect data on
durations of phases of a batch process.
 Gantt charts (MS project)to depict constraints for batch processes.
(Critical path).
 Software such as Intelligen, SchedulePro® batch software
13

14. MAP PROCESS UNITS TIMES (Petrides 2007)
14

15. GANTT gives bottleneck critical path (Petrides 2007)
15

16. EQUIPMENT UTILIZATION SHOWS
BOTTLENECKS (Petrides 2007)
16

17. ADD CRITICAL EQUIPMENT TO
DEBOTTLENECK (Petrides 2007)
17
Cycle
Time
Reduced
13%

18. ASSESS CAPACITY BOTTLENECKS –
CONTINUOUS PROCESSES
 Talk to the operators for clues
 Aspen or other simulator- to check for bottlenecks
when unit ops are well understood.
 Certain things can’t be predicted by simulators,
Fouling behavior.
Catalyst activity.
 FRI rating program for distillation towers
 Well-designed test runs, under representative
conditions. (Texas summer versus winter, for cooling).
18

19. Beware of tricks/traps in assessing
bottlenecks I.
 Hydraulics - Line sizes, Pumps and pump suction conditions
(NPSH)
 Powder handling systems, including pneumatic conveying
systems
 Bottlenecks can be right behind each other.
 Story moment: Spray dry dryer was bottlenecked by
performance of rotary atomizer. Replaced it and found
that pneumatic conveying system downstream was
limiting, right away.
19

20. Beware of tricks/traps in assessing
bottlenecks II.
 Assess your Quality – check the quality required by your
customer . Sometimes relaxing quality can get more capacity.
 Story moment: water level in a product.
 Organic product was dried in process by molecular sieves
which were a bottleneck. It had a very low water level
specification, to avoid freezing problems in cold weather
applications.
 All customers had shifted to use in warm locations on US
Gulf Coast.
 Water level spec was then relaxed with customer approval,
eliminating process bottleneck.
20

21. Beware of tricks/traps in assessing
bottlenecks III. (Jaafar 2005)
 Use Gamma ray scans to assess distillation tower performance
21

22. Gamma-ray scans of towers
22
Liquid level on trays
Distillation tower loading: Gamma-ray
scans of towers are very helpful.
(Jaafar 2005)

23. Gamma-ray scans of towers
23
Liquid level on traysJaafar 2005)

24. Summarize unit capacities – where
are the bottlenecks? (Litzen, Bravo 1999)
24

25. OUTLINE
 DEBOTTLENECK BACKGROUND
 ASSESSMENTS - where’s your problem?
 CURRENT PRODUCTION LOSSES
 CURRENT VS FUTURE UNIT CAPACITIES
 TRICKS AND TRAPS
 SOLUTIONS
 INCREASE EQUIPMENT CAPACITY
 PROCESS SIMPLIFICATION
 PROJECT MANAGEMENT FOR DEBOTTLENECK
(REVAMP) PROJECTS
25

26. INCREASING CAPACITY I. - EQUIPMENT
 Pumps – sometimes one can replace an impeller in
centrifugal pumps.
Trap: Check motor hP and NPSH first!!!
 Heat exchangers - Larger, more plates, corrugated tubes,
twisted tubes
Trap: If upsizing diameter to get more A, we can
reduce shell side velocity and U.
 Powder processing – vibrating bottom bins. Steeper bin
walls, larger vessels, mass Flow screws.
Story moment: powder feed system for extrusion was
under producing. Cohesive powder being fed through
2” bin outlet, 60º angle walls.
Increased to 6” with 70º angle, solved problems
26

27. INCREASING CAPACITY II. - REACTIONS
 Catalyst modification in catalytic reactors for improved yield, or
selectivity (check tosca)
 Increasing active concentration in batch reactions. Story moment:
emulsion polymerizations, story time, increase capacity 60% by
increasing emulsion activity from 25% to 40%.
 Use a separate post treatment vessel, for example to scavenge
residual reactant or to wash out impurities.
27

28. INCREASING VACUUM DISTILLATION
TOWER CAPACITY (from Fair 1996)
28
Stepwise debottlenecking of trays operating at low pressure
Action Advantages Disadvantages
Increase pressure More capacity
No column changes
Lower relative volatility
Higher temperatures
Decrease hole size More capacity New tray panels
Change style of tray (e.g., to
Nye, MD=multiple
downcomer)
More capacity New tray panels
Possible downcomer
modifications
Possible increase in # of
trays and support rings
Switch to structured packing More capacity, if larger
height
Lower pressure drop
Cost of packing and
attendant hardware
Cost of removing trays and
tray rings
Install new high-capacity
device
(e.g., cocurrent tray)
More capacity Higher pressure drop
Cost of new device
Cost of removing old trays
and possibly tray rings

29. INCREASING PRESSURE DISTILLATION
TOWER CAPACITY (Fair 1996)
29
Stepwise debottlenecking of trays operating at high pressure
Action Advantages Disadvantages
Enlarge downcomers and
increase open area
More capacity Loss of active area
Cost of modifications
Change style of tray (e.g.,
to MD)
and decrease tray
More capacity Lower efficiency; need more
Cost of new trays
Cost of removing old trays and
some tray rings
Switch to larger-size
structured packing
More capacity Lower efficiency
Costs of removing and replacing
packing
Install new high-capacity
device
More capacity Higher pressure drop
Cost of new device
Cost of removing old device

30. IMPROVED PROCESS CONTROL
 Shorten transitions
 Stabilize process & operate closer to our capacity
limits
 Operate closer to our quality limits
30

31. Further equipment debottleneck
modes (Rangaiah 2016)
31
Equipment/System Debottleneck mode
Pneumatic system -
increase capacity
Change air velocity, air-to-solid ratio, blower
speed, screw or rotary valve speed
Centrifugal
compressors
Modify internals, including rotor; increase
Conveying fans Install bigger impeller and/or additional fans in
parallel.
Reduce pipe/duct pressure losses
Fin-Fan coolers Increase fan pitch angle and/or fan speed,
reduce tip clearances, install inlet bells,
fan seal disk and/or high
Mixers Use static mixers or high-shear rotary disperser
to retrofit/replace
existing tank mixers.
Vacuum systems Install pre-condensers cooled with
cooling/chilled water. Use multi-stage steam
ejectors arranged in series/series- parallel
arrangement.

32. OUTLINE
 DEBOTTLENECK BACKGROUND
 ASSESSMENTS - where’s your problem?
 CURRENT PRODUCTION LOSSES
 CURRENT VS FUTURE UNIT CAPACITIES
 TRICKS AND TRAPS
 SOLUTIONS
 INCREASE EQUIPMENT CAPACITY
 PROCESS SIMPLIFICATION
 PROJECT MANAGEMENT FOR DEBOTTLENECK
(REVAMP) PROJECTS
32

33. Process Simplification
 Ways to simplify process, using ingenuity with minimal
technology risk?
 Can challenge the accepted norms?
 Parallel reactor usage, instead of series. Story
moment: Two reactors in series for polymer line
converted to parallel, doubled plant capacity for very
low investment.
33

34. 34
Reactor 1
Conversion
Monomer 2
Monomer 1
Initiator
Continuous
flow reactors
in series
Reactor 2
Residual scavenging
Radical Scavenger
Devolatilizer
Reactor 1
Monomer 1
Initiator + Scavenger
Reactor 2
Devolatilizer
Monomer 2
Continuous
flow reactors
in parallel
Doubled
Production by
Putting 2
Polymer
Reactors in
Parallel
Instead of
Series

35. INCREASING CAPACITY IIIa.- Feeds
35
BATCH POWDER BLENDER
Powder 1
Powder 2
Liquid ingredient
Batch feed
Single Screw Extruder
Manual
loading to
powder
blender
Pharmaceutical dispersion made from single screw extrusion,
melting down and making micro droplets out of a powder blend.
Team replaced the 2 step operation by a single-step compounding
and meltdown in a twin screw extruder.

36. INCREASING CAPACITY IIIb.- Feeds
36
Twin Screw Extruder
Continuous
feed to
extruder
Mass flow
powder feed
Powder 1
Mass flow
powder feed
Powder 2
Liquid pump
Liquid Ingredient
Eliminate powder blender. Use Twin-screw, doubled capacity and
improved quality & ergonomics

37. OUTLINE
 DEBOTTLENECK BACKGROUND
 ASSESSMENTS - where’s your problem?
 CURRENT PRODUCTION LOSSES
 CURRENT VS FUTURE UNIT CAPACITIES
 TRICKS AND TRAPS
 SOLUTIONS
 INCREASE EQUIPMENT CAPACITY
 PROCESS SIMPLIFICATION
 PROJECT MANAGEMENT FOR DEBOTTLENECK
(REVAMP) PROJECTS
37

38. What’s different about debottleneck
projects? I.
 Debottleneck projects build onto/into all the sins of the past.
 Heavy dependence on accurate facility data for existing plant.
 Requires extensive field verifications of what’s in the plant
(drawings, manuals, specifications and performance histories).
But! Sometimes our surveys can’t access easily what’s already
there, OR it’s under insulation.
 Need to have good drawings, PIDs, ISO drawings. Most plants
don’t have them up to date. Need a budget for this prework!
 Laser scans of piping can be useful. (Image from PTQ)
38

39. Laser scanning of piping (Smith 2015)
39
SCAN THE
PLANT
CONVERT POINT
CLOUD INTO 3D
MODEL

40. What’s different about debottleneck
projects? II.
 The existing plant is a stakeholder. Heavy dependency on
cooperation with existing plant leadership, and their production
plan.
 Usually the work is constrained to a short period. If performing
work during an overall plant shutdown, integrate the work into an
overall project plan for the plant’s work.
 Budget for plant staff time in the project – it’s extensive.
 Budget for staff, time, budget and responsibilities for pre-cleaning
the equipment. Account for any waste disposal.
 Budget & plan for inclusion of the modifications into existing plant’s
IT systems and databases, such as maintenance and mechanical
integrity.
40

41. Debottleneck Project Traps I.
 Be sure to define a good owner scope agreement, detailing
what plant problems WILL be fixed and what WON’T.
 If adding a new unit, will you fix the problems with the
old one?
 Will you demolish or mothball in place?
 Constructibility studies are key. Piping, utilities conflicts,
safety (working near other work), available space, laydown
areas, use of existing foundations.
 3D CAD models are indispensable for revamp projects
41

42. Debottleneck Project Traps II.
 Be wary of condition od existing, mothballed equipment. Plant
may say “we have another one available.”
 Cleaning, MI inspection
 Check last performance.
 Budget for the above
 Lots of carbon steel out there; modification can be difficult.
 Story moment: Carbon steel, versus stainless steel in
new lines. Carbon steel was cheaper, but with the pre
and post-weld heat treatment needed, it cost more in
these services and delays waiting.
 Pipe replacements go flange to flange when possible.
Modification of vessels can take time:
 Rerating vessels for new conditions takes time.
 Code approvals for modifications also require time.
42

43. Debottleneck Project Traps III.
 Harder to estimate cost.
 No simple costing “rules of thumb,” such as 4x to 8x
major equipment cost
 More contingency.
 More engineering, per $ of capital cost.
 Add productivity allowances for labor, in such projects.
 Add allowances (in cost and schedule) for field
adjustments and fit-up.
 Check everything and communicate the scope well to your
EPC.
43

44. Scope must include OSBL and HES
 Utilities - water, air, steam, and probably most important electrical
power.
 Include logistics and packaging, storage, filling systems.
 Check your environmental permitting implications for the new
capacity! Incorporate into the project plan.
 Enviro abatement systems need to be checked.
 Safety systems need to be checked. Reliefs need to be checked.
Watch you’re not operating too closely to relief points and rupture
discs burst points. (Rupture pin, instead of disc, can be useful)
 Facility siting (safety) studies, if adding new storage.
 Story moment: OSHA auditee was required to show all past capacity
increases and show verifications that the relief valves were checked
each time.
44

45. DISCUSSION AND QUESTIONS
45

46. REFERENCES and Further Reading
Joseph C. Gentry, Succeed at Plant Debottlenecking, Chemical Processing, Mar 10, 2004. A basic introduction with specific examples.
S. Ottewell, Debottlenecking Takes A Broader View, Chemical Processing, April 18, 2011. Treats use of simulation.
Hans-Jürgen Bittermann, Dr. Jörg Kempf, Debottlenecking: Exploiting Opportunities to Boost Performance, Process Worldwide.com, 10/17/2014, downloaded 24 Sept 2016.
D .F. Schneider, Debottlenecking Options and Optimization, white paper of 1997, downloaded 24 Sept 2016.
Manganaro, J. L. Estimate the Capacity of Simple Batch Processes. Chemical Engineering Progress, 98(8): 70-75, August 2002.
GP. Rangaiah, Chemical Process Retrofitting and Revamping, Wiley, 2016.
N. P. Lieberman, Process Engineering for a Small Planet, Wiley 2010.
Litzen and Bravo, “Uncover low-cost debottlenecking opportunities,” CHEMICAL ENGINEERING PROGRESS • MARCH 1999
L. J. Cabano, Retrofit projects: the ultimate management challenge, Chemical engineering progress, 1987, vol. 83, no 4, pp. 27-31
Fair, J. R., and A. F. Seibert, “Understand Distillation-Column Debottlenecking Options,” Chemical Engineering Progress, 92, (6), p. 42 (June 1996).
Seiichi Nakajima, “Introduction to TPM and TPM Development Program,” Japan Institute for Plant Maintenance 1988. Translated into English, Productivity Press, ShopFloor
Series, called “OEE for Operators.”
Pablo F. Navarrete, William C. Cole, Planning, Estimating, and Control of Chemical Construction Projects, Second Edition, CRC press, 2001
Distillation-How to Push a Tower to Its Maximum Capacity: Proper analysis and operating adjustments help boost separation capacity without increasing flooding, Simon X. Xu,
Charles Winfield, John D. Bowman Tru-Tec Services, Inc.; Shelley, Suzanne. Chemical Engineering105.8 (August, 1998): 100.
G. Towler, R. Sinnott, Chemical engineering design : principles, practice, and economics of plant and process design, 2nd ed., Elsevier (2013)
D. H. Stamatis, “The OEE Primer: Understanding Overall Equipment Effectiveness, Reliability, and maintainability” CRC Press, 2010.
R. Ogle and A. Carpenter, Chemical Engineering Progress August 2014, Calculating the capacity of chemical plants.
Al-Zahrani; Bright, S; Roy, E; S.. Debottleneck crude-unit preheat exchanger network inefficiencies.Hydrocarbon Processing (Feb 2012).
M. Smith, Laser scanning for revamps, PTQ, 39-43, 2015
Petrides et al, “OPTIMIZE MANUFACTURING OF PHARMACEUTICAL PRODUCTS WITH PROCESS SIMULATION AND PRODUCTION SCHEDULING TOOLS,” Chemical
Engineering Research and Design Trans IChemE, Part A, July 2007
Jaafar, HYDROCARBON ASIA, JAN/FEB 2005, “Gamma-ray scanning for troubleshooting,….”
M. Smith, “Laser Scanning for Revamps” PTQ 2015
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