Polymerisation is an exothermic reaction, and the defining engineering question in this sub-sector is what happens when heat removal fails. Runaway reaction is the credible worst case on most resin and polymer plant, and the basis of safety, whether that is cooling capacity, emergency relief, reaction inhibition or containment, is a design decision that has to be made explicitly and evidenced.

Projex Solutions provides engineering design, process safety studies and project delivery for polymer, resin and elastomer producers, from reaction through to finishing and material handling.

What makes this work different

Thermal runaway is the design case. Heat generation rises with reaction rate while heat removal is limited by surface area and coolant. Reaction hazard data, adiabatic temperature rise and time to maximum rate underpin the whole design, and where that data is thin, the engineering is guesswork.

Emergency relief system design is specialist. Sizing relief for a two-phase reacting system is not the same problem as sizing relief for a gas or liquid service, and the discharge has to go somewhere that has been assessed.

Finishing brings dust. Pelletising, grinding, drying and conveying of polymer produce combustible dust, so a site with a well-controlled reaction hazard can still carry an unassessed explosion risk in its finishing hall. Dust zoning falls under DSEAR with classification to BS EN 60079-10-2.

Monomer inventory drives COMAH. Many monomers are both flammable and toxic, and bulk storage frequently determines tier status independently of the process itself.

Batch and continuous coexist. Sites often run batch reaction into continuous finishing, which puts the surge, buffering and control design at the interface between the two.

Where we help

  • Reaction hazard review and basis of safety definition, working from calorimetry data where available and identifying where it is needed
  • Emergency relief system review, including two-phase relief considerations and discharge routing
  • HAZOP and HAZID facilitation, LOPA and SIL determination to BS EN 61511
  • Dust explosion protection design for finishing and handling, covering venting, suppression and isolation
  • DSEAR assessment and hazardous area classification for both gas and dust
  • Reactor, heat transfer and cooling system design, including emergency cooling provision
  • Monomer storage and handling design, with inhibitor management considered
  • COMAH support, feasibility and FEED, detailed design and EPCM delivery under ISO 9001:2015

Typical reasons clients get in touch

  • A new product or catalyst system changes the reaction hazard profile
  • Relief system sizing has not been reviewed against current understanding of the reaction
  • Dust explosion risk in finishing has never been formally assessed
  • Cooling capacity limits batch size, cycle time or product range
  • A capacity increase requires reactor or heat transfer modification
  • Monomer storage needs reviewing against COMAH thresholds

Related

Part of our work across the chemical sector. See also petrochemical derivatives and adhesives, sealants and construction chemicals.

Standards and regulations we work to

  • COMAH 2015, where monomer inventory crosses threshold
  • DSEAR 2002, with ACOP L138 (second edition, 2013)
  • BS EN IEC 60079-10-1:2021 for gas, and BS EN 60079-10-2 for dust
  • BS EN 61511-1:2017+A1:2017 for safety instrumented systems
  • PSSR 2000, with guidance L122 (2014)
  • COSHH 2002, with ACOP L5 (sixth edition, 2013)
  • Environmental Permitting (England and Wales) Regulations 2016 (as amended)
  • CDM 2015 and ISO 9001:2015

Frequently asked questions

What reaction hazard data do you need before designing a reactor?
At minimum, the heat of reaction, the adiabatic temperature rise and an indication of time to maximum rate under adiabatic conditions. Where that data does not exist, we would rather say so and recommend calorimetry than design around an assumption.

Our relief system was sized years ago. Should it be reviewed?
If the process, catalyst system or batch size has changed, yes. Relief sizing for a two-phase reacting system is a different calculation from single-phase gas or liquid relief, and the discharge routing has to be assessed as well as the orifice.

We control the reaction hazard well. Why are you asking about the finishing hall?
Because pelletising, grinding, drying and conveying generate combustible dust, and dust explosion risk in finishing is frequently unassessed on sites with otherwise mature process safety. The two areas tend to be managed by different people.

Can you increase our batch size?
Sometimes, but cooling capacity is usually the limit rather than vessel volume. That is a heat transfer question, and it is answerable with the right data.

Does a change of catalyst need a new HAZOP?
It needs assessing. A catalyst change can alter reaction rate, exotherm profile and the effectiveness of existing controls, and where it does, the existing HAZOP no longer describes the process being run.

Can dust protection be retrofitted to an existing finishing line?
Usually yes. Venting, suppression and isolation can all be added to existing equipment, though isolation between connected vessels is the part most often overlooked and the part that prevents propagation.

Talk to us about your process. Request a call