Innovative solutions for CO2 utilization and reduction in urea plant

The urea plant is considered one of the largest sources of carbon dioxide emissions. This is due to hydrogen production via steam-methane reforming (SMR), which requires a large amount of heat. In this work, carbon dioxide from the flue gas of the SMR furnace was captured by a membrane unit and then recycled to the urea reactor. However, additional ammonia was needed to maintain the NH 3 /CO 2 ratio, but producing hydrogen from SMR will generate carbon dioxide again, creating an infinite loop. In this work, an innovative solution was proposed by recycling hydrogen from the tail gas of the atmospheric residue desulfurization (ARDS) unit using a membrane system. The case study was conducted in UniSIM® process simulator using data from the previous urea plant of Petrochemical Industries Company (PIC). This study provided two solutions for a plant capacity of 700 metric tons of urea per day. The first solution increased urea production by 30% when 34% of carbon dioxide was captured from the SMR flue gas. The estimated payback duration was around 3 years. The second solution was to use the hydrogen from the membrane to partially replace SMR hydrogen without generating more urea. This option reduced carbon dioxide emissions by 39%, and the expected payback duration was about 6 months.