Economic Loss Risk-Based Reliability and Maintenance Assessment for High-Pressure Methanol Plant

Abstract

This paper assesses maintenance costs and reliability associated with additional risk reduction measures in a methanol plant to achieve an “as low as reasonably practicable” (ALARP) target risk level of 1 × 10⁻⁷ yearly. It proposes an approach to evaluate maintenance and reliability using economic loss risks, focusing on incidents involving piping and reactor operations. The study examines economic losses from fatalities, injuries, equipment damage, business interruptions, and emergency services due to toxicity, thermal radiation, and overpressure events at different reactor pressures. Case studies involve comparing five plants: a 76 bar normal methanol plant with a 42 m³ reactor and four modified plants with 7.6 m³ reactors at pressure of 76, 200, 350, and 500 bar. The methanol reactor contains hazardous substances: hydrogen, carbon dioxide, carbon monoxide, and methanol. Losses, including fatalities, injuries, equipment damage, are estimated by combining consequence analysis outcomes with individual and equipment values. Business disruptions consider downtime and industry value added per employee, while emergency service losses amount to two percent of the total. Results indicate the normal methanol plant needs RM 12.7 million annually for maintenance to achieve ALARP, while modified plants reduce costs by 75% to 91% compared to the normal methanol plant.