Summary
Samenvatting process safety (2300WETPRS)
- Course
- Institution
This is a complete summary of everything handled in this course, including remarks from the lecturers and several examples explained
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1Summary Process safety
Part 1 : Batch processing
Large scale batch equipment
- Generally, a larger version of lab scale equipment
o 1000L-6000L-10 000L vessel (bulk is underground)
▪ The larger the vessel, harder to get temperature control and more inefficient
stirring
▪ Larger than this are uncontrollable
o Manhole to add solids
o Stirrer
o Electronics to control the stirrer, temperature
o Complex glass design
o Heating/cooling jacket
- Less accessible then lab equipment
The batch reactor in general:
- Workhorse in the industry (fine and pharmaceutical
chemistry)
- 50L -> 10 m³
- Mostly overhead stirring
- Cooling/heating through jacket
- Different flangers (ports) for addition/removal of reagents,
probes …
- Manhole to add solids
- Bottom drain valve
o Slurry liquids with much solids in them can be
difficult to remove because of this
- Limited visibility
o Problem with crystallization reactions to see if they
have started yet
- Everything (charging, heating, mixing) takes longer
o Can affect the chemistry, safety,…
Centrifuge:
- Closed
o Easier for products which are vulnerable to oxidation (compared to lab scale)
- Different scales possible
- Mostly used in the fine scale and pharmaceutical industry
Pressure filter:
- Closed
o Easier for products which are vulnerable to oxidation (compared to lab scale)
Summary process safety Wout De Wachter
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- Different scales
- Comparable to a glass filter
o Pressure is used instead of vacuum
- Stir is possible
Before you start : retrieving safety information
- First safety test is always a dry test
o Think, read, surf about the chemistry
o Before start doing things
- Use the SDS (safety data sheet) as a starting point
o Standardized format
o Not standardized content
▪ The information for the same compound may differ for different supplier
▪ Labelling and identification of hazards differ by country
▪ Use EU based SDS whenever possible
- Check the labeling (GHS pictograms)
o One label my cover wide range of properties
o Labelling may change over time !
▪ New legislation
▪ Ends up on the SVHC list (substances of verry high concern)
- Check other relevant data
o Boiling / melting point
o Reactivity, know incompatibilities : no data = not necessarily safe !
o Water reactivity !
▪ Quite often gives a lot of heat and or gasses ! → dangerous!
o How to deal with spill
o How to deal with fire
o Storage conditions
- Information may differ between suppliers
- Belgium : Acros website to start looking for an SDS
- Mind the correct naming of compounds
Summary process safety Wout De Wachter
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- Check Bretherick’s handbook of reactive chemical hazards
o List of all reported reactivity incidents sorted by compound
- For compatibility data : start with the chemical reactivity worksheet (from aiche.org)
o Database of common chemicals
o Individual safety concerns given per compound
o Indication of compatibility in complex mixtures
Personal protective equipment
➔ For protection against external influences
Type of PPE needed:
- Legally defined
- May also be company dependent
In lab environment:
- Safety glasses
- Lab coat
- Gloves
o Not latex to prevent allergic reactions
o Preferably nitril gloves
- Always work in fume hood
- Sometime respiratory PPE may be needed
In plant:
- Safety glasses , face shield if needed
- Safety overall
- Gloves : more resistant types then the ones in a lab
o Also, possible specialty gloves (hot/cold work , anti-slip, anti-cut)
- Helmet
- Safety shoes
o impact
o antistatic (flamatory environment)
o splash resistance
- Respiratory protection according to need
o Dust
o Gas/vapor
o 2 types:
▪ Respirators / filtering equipment : full/half face mask
• Full face masks : difficulties with glasses as they will break the tight
seal
▪ Breathing apparatus : supply of fresh air from another source
- Hearing protection according to need
Summary process safety Wout De Wachter
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Important factor when discussing respiratory protection equipment : assigned protection factor
(APF)
- Indicator for protection efficiency
- Higher = better
- = the amount of time you can multiply your expose with
o No protection : APF =1
o Respirator : APF =50
▪ You can work 50 times longer in an environment then without any
protection
- Legally defined
- Tight fit is verry important
o Beard, piercing etc. have an influence
Fire and explosion risks
heat
➔ Most serious industrial chemical incidents involve explosion and/or fire
➔ Fire is often a secondary effect but the most damaging
➔ Fire triangle applies for both dust and gas/vapor
o Removing any of these prevents the fire:
o Oxygen
▪ Inerting as preventive measure (N2 or Ar) as an atmosphere
o Ignition source = heat / energy
▪ Use certified spark-free instrumentation
▪ Avoid hot surfaces
o Fuel
▪ Flammable Solvents/dust with a flashpoint < 60°c
▪ Above certain threshold volume : rules apply
➔ Heat alone can be sufficient for ignition : product dependent auto ignition temperature
o When the compound is subjected to a temperature higher than its auto ignition
temperature, the compound will spontaneously ignite
o Is usually very high and not significant
o Care for hot surfaces is needed when working with low AIT compounds
o In plants, equipment specifically designed to avoid overheating (T1-T6)
▪ Indicates with each equipment what the maximum possible temperature is it
could reach (even when malfunctioning)
Summary process safety Wout De Wachter
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