According to Britannica.com. the Bermuda Triangle is a section of the North Atlantic Ocean off North America in which more than 50 ships and 20 airplanes are said to have mysteriously disappeared. Wikipedia goes on to note that in 1952 Fate magazine published "Sea Mystery at Our Back Door", where the author recounted the loss of several planes and ships since World War II. A geography not to be messed with, it seems.
Similarly, in the realm high hazard processing facilities, another challenging geography is the Green Ammonia triangle.
Green Ammonia production is likely to far outweighs the more polluting black, grey or blue production methods, as we transition to a fossil free future. As materials develop, advances in Polymer Electrolyte Membrane (PEM) technology for electrolysers yields greater efficiencies year on year. The route to produce ammonia as a Liquid Organic Hydrogen Carrier (LOHC) brings significant transportation benefits when comparing transportation of liquid H2 in its virgin state.
However, a triangle of significant hazards exists during the ammonia production process, namely:
- Nitrogen manufactured from an Air Separation Unit, consists of asphyxiant & cryogenic hazards.
- Hydrogen possesses very low minimum ignition energies (0.017mJ) & has a significant explosive fuel range (4-75% v/v) & will generate a deflagration producing a significant pressure wave (550 bar m/s).
- The resultant ammonia (produced by the Haber Bosch process) is highly toxic.
At each stage of process design, especially at conceptual, it is imperative to make wise choices of plant/equipment layout. A HAZID study (HS 2) will tease out the safeguard requirements, for example:
- Blast Walls - however an inherently safe design (ISD) may be favoured negating this.
- Spacing of equipment / minimise congestion will help to reduce pressure wave magnitude & assist for equipment inspections or routines. Plant layout is a critical factor not only for constructability but will assist a Reliability Centred Maintenance (RCM) approach and process release of units.
HAZOP (HS 3) must consider an ISD, versus Safety Instrumented Functions which not only need to be appropriately designed (IEC 61511) but maintained for the life of the plant. Any upgrades or changes must be covered by appropriate Functional Safety Audits (FSA’s). DSEAR will need to be followed and adopted prior to final confirmed locations.
Finally, consideration of plant hazards for startup/shutdown must be allowed for, as this is when the plant is at its greatest change of flux. Level-headed decisions need to be made for credible unplanned scenarios, with the appropriate safeguards in place to mitigate any potential loss of containment for any of the plants fluids. Add the hazards of high voltage electrical supply required for the electrolysers into an aqueous rich environment.
In conclusion, the new geography of green ammonia is likely to be a high reward one for those who choose to enter. Just take care to identify the hazards so that your residual risks can be rendered known and low.
Blog by Paul Gornall from Process Safety Matters
