Improved efficiency and reliability with new hydraulic energy recovery design for CO2 removal in ammonia plants

摘要

The CO2 removal process in ammonia production is a significant contributor to overall plant energy consumption. Energy costs can be reduced by recovering the energy wasted across the absorber pressure letdown valve. Historically, this has been accomplished with a hydraulic recovery turbine, or reverse running pump, coupled in a long train to the process pump. This paper presents an innovative new energy recovery solution based on a proprietary liquid-phase turbocharger and integrated controls system. This new solution offers high operational efficiency and improved reliability for substantially longer on-stream time. The IsoBoost? Energy Recovery System is an integrated, skid mounted unit which recovers up to 80% of the rich solvent hydraulic energy and transfers it directly to the semi-lean solvent in a liquid-phase turbocharger. The fluid to fluid energy recovery in the turbocharger eliminates the need for a shaft connection to the process pump as well as subsequent long train of clutch, couplings, intermediate bearings and mechanical seals. Industry reliability data shows that mechanical seals are the number one cause of pump failure. The design of the turbocharger, including no mechanical seals, results in a low maintenance system with high mean-time-to-failure of 10 years. A complete description of the IsoBoost system will be presented along with performance and reliability data and cost savings.