Cold Rich Bypass to Strippers for CO2 Capture by Concentrated Piperazine

Cold rich bypass to the stripper in CO2 capture by alkanolamines will usually reduce the total heat duty. Bypass reduces the stripping steam in the overhead vapor and balances the temperature approach in the main cross exchanger. This process improvement reduces the energy requirement of any configuration, but it is most beneficial when the overhead vapor is not already countercurrently contacted with incoming rich solution. Therefore, the 2-stage flash configuration was evaluated in this work, and it had an improvement of 11% over the no bypass case. Its improvement was better than what was observed with a simple stripper and interheated column. An optimized cool rich bypass for a pilot scale 2-stage reduces the equivalent work.