PROCESS FLOW DIAGRAM:
POLYETHYLENE
By: Cameron Shaw
Daniel Couto
Daniel LeClair
Leigh Bedford
Nicole Rich-Portelli
Compressor: initial compression of ethylene feed to 1500 bar
Hyper-compressor: compensates for pressure loss in recycle
stream and outlet feeds to restore reactor inlet pressure to 2000
bar
Reactor: Plug Flow Reactor (PFR) inside a cooling jacket
T = 70C, P = 2000bar
Separator: main source of pressure loss
polymer solids fall to bottom and are sent to extruder
unreacted ethylene recycled back to reactor
Process Overview
PROCESS OVERVIEW Major safety concerns are around the plug flow
reactor:
Free radical polymerization of ethylene to polyethylene is a highly exothermic reaction
Converts gaseous ethylene into viscous polyethylene melt
Thus many constraints must be taken for a process that aims to be effective and safe:
reactor temperature (prevent unideal and dangerous temperatures)
reactor pressure (prevent pressure increases and decreases in reactor)
flow rate in reactor (prevent unideal flow rates)
HAZOP
HAZOP – “LOW” TEMPERATURE
HAZOP – “HIGH” TEMPERATURE
HAZOP – “LOW” PRESSURE
HAZOP – “HIGH” PRESSURE
HAZOP – “LOW” FLOW
HAZOP – “HIGH” FLOW
HAZOP – “REVERSE” FLOW
HAZOP - FINAL
CHEM ENG 4N04 SDL Project - The Production of
Formalin from Methanol
Group B4
Matt Galachiuk - 0752265 Kyle Kovacs - 0849889
Sana Shamsher - 0456846 Angela Zeinstra – 0842631
Honorable Mention: Jervis Pereira
Process Overview and Principles
Reaction Kinetics and Principles
CH₃OH + ½O2 → CH₂O + H₂O ΔH RXN = -156 kJ/mol CH₃OH → CH₂O + H₂ ΔH RXN = 85.0 kJ/mol
Operating temperature: 900 to 950K - resulting selectivity? - resulting conversion? Operating pressure: atmospheric Catalyst: silver
Figure: G. A. Bowmaker, G. I. N. Waterhouse, J. B. Metson. “Mechanism and active sites for the partial oxidation of methanol to formaldehyde over an electrolytic silver catalyst.” Applied Catalysis A: General, vol. 265, no. 1, pp.85-101, June 2004.
Catalyst Regeneration
Frequency of replacement: every 3 years Frequency of regeneration: every 1.5 years Process to regenerate catalyst: flood with cesium salt solution - catalyst remains in reactor Volume of catalyst needed: 2 m3 - based on mass balances and a linearly deactivating catalyst Mass of catalyst needed: 21 000 kg - based on a density of 10 490 kg/ m3
Production Losses
Two shut downs in a 3 year period (lifetime of catalyst) Shutdowns last for 1-2 weeks each 1st shutdown: full maintenance, catalyst regeneration 2nd shutdown: full maintenance, catalyst replacement
ITEM FREQUENCY COST
Lost production Twice in 3 years $ 400 000
Maintenance Twice in 3 years $ 160 000
Replacing catalyst Once in 3 years $ 10 000 000
Regeneration Once in 3 years negligible
TOTAL $ 11 120 000
Class Activity – HAZOP Analysis
Guide Word
Deviation Causes Consequences Existing
Protection Recommendations
High Level in separator is too high
Low Level in separator is too low
None There is no liquid in the separator
Class Activity – HAZOP Analysis
Janine HoJannany Srichandra
Claudia ChanKushlani Wijesekera
Chris Paslawski
November 22, 2012
[Diagram provided by the Burlington Water Purification Plant]
[Simplified from P&IDs provided by the Burlington Water Purification Plant]
Overall Scope
Flocculation and Sedimentation
[Simplified from P&IDs provided by the Burlington Water Purification Plant]
Recycled
microsand
Raw water
from low lift
Sludge to waste treatment
Sulfuric
Acid
Alum
Polymer
Fresh microsand
To ozone contactor
DrainDrain
Drain
Drain
Ozone Contactors
Ozone recycle
Sodium
BisulphiteHydrogen Peroxide
Settled water
(From Settling
tanks) To Filter
Ozone
[Simplified from P&IDs provided by the Burlington Water Purification Plant]
Ozone Contacting
Ozone Quenching
To Ozone Destructors
Operability: Requirements:
90% of 113ML reservoir capacity
Water Quality constraints set by Ministry of Environment of Ontario:
Turbidity
pH
Fluoride ion concentration
Colour
Ozone
Mircoorganisms: Crypto, Giarda, Choliform Bacteria
Operating Window-Turbidity
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 50 100 150 200
Tu
rbid
ity
[NT
U]
Output Flow rate [ML/day]
0
0.2
0.4
0.6
0.8
1
0 50 100 150 200
Co
nce
ntr
ati
on
of
Flu
ori
de
[m
g/L
]
Output Flow Rate [ML/day]
Operating Window -[Fluoride]
Reliability
Reliability =
Probability of failure =
Availability =
Back-Up Equipment
Ozone contactors (4 total, 2 currently in use)
3 Pairs each of low and high-lift pumps (55, 75, 97 ML/day)
By-pass valve for raw water
Diesel-run generator in case of power outage
Safety and Control Operation is controlled by the SCADA (Supervisory
Control and Data Acquisition) system:
Centralized monitoring and control for multiple inputs and outputs.
Collects field data, transfers this data to a central computer through controllers (eg. PLC), and then displays information to the operator on a screen.
P&ID for Settling Section
pH
Recycled
microsand
Raw water
from low lift
Sludge to waste treatment
Polymer
Fresh microsand
To ozone contactor
DrainDrain
Drain
Drain
LSHH
Turb
Sand
pH
Recycled
microsand
Raw water
from low lift
Sludge to waste treatment
Polymer
Fresh
microsand
To ozone contactor
DrainDrain
Drain
Drain
LSHH
Turb
LC
LAH
FO
Recycle Stream
pH
Recycled
microsand
Raw water
from low lift
Sludge to waste treatment
Polymer
Fresh
microsand
To ozone contactor
DrainDrain
Drain
Drain
LSHH
Turb
LC
LAH
FO
Turb
Turb C
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