Fatality assessment for high pressure reactor of methanol production plantsfrom CO2 hydrogenation / Mohd Aizad Ahmad and Zulkifli Abdul Rashid

New technology emerges for carbon dioxide hydrogenation where captured carbon dioxide reacts
with hydrogen for methanol production using high pressure condition up to 442 bar. The research on
high pressure process focus on how much percentage of carbon dioxide and hydrogen converted,
accompanied with how much percentage of methanol selectivity. There is no comprehensive study
on safety, especially in term of consequences to human fatalities if incident occurred at this highpressure plant. Therefore, the purpose of this paper is to assess percentage of fatalities occur for
reactor methanol (MeOH) plant operates at high pressure of 442 bar. It studies the possibility on (i)
various events occurred in term of toxicity, thermal radiation, and overpressure; and (ii) estimation
of percentage of fatalities when all that events occurred in comparison with reference plant operating
at reactor pressure of 76 bar. Process plant is simulated using HYSYS and the obtained mass density
of mixture, mass fraction, and volume fraction of chemical are used to calculate amount of toxicity
(ppm), thermal radiation (kW/m2
), and overpressure (psi) using consequence model simulated in
ALOHA software. Threat zones generated by ALOHA software are then exported to the MARPLOT
software to observe the area affected by the case study. The studied methanol reactor releases
chemical mixture consists of hydrogen, carbon dioxide, MeOH, carbon monoxide (CO), and water,
which only water is not considered as hazardous material. The release of chemical mixture observed
for 10 mm, 25 mm, and 160 mm leakage, simulated at day and night conditions. The result for plant
that operates at pressure of 442 bar has the highest severity of 44% fatality, which comes from the
event of flammable methanol jet fire at daytime, leakage of 160 mm hole size. Meanwhile, for plant
operating at 76 bar, the highest fatality is 27%, occurred from toxicity release of carbon dioxide at
nighttime, leakage of 160 mm hole size.