Chilled Ammonia Process Scale-up and Lessons Learned

Abstract

The GE Chilled Ammonia Process (CAP) is a post combustion CO2 capture technology that produces a high purity CO2 product stream that can be utilized in the existing and new markets. The development of the CAP technology began with laboratory bench-scale experiments to confirm that aqueous ammonia solution effectively absorbs CO2 with sufficiently low vapor phase ammonia emissions at reduced temperatures. From these results, a technology development program was initiated to scale-up and validate the process for commercialization.The approach taken here is illustrative of industrial scale process development and improvement. For the CAP CO2 capture technology, the development effort involved an iterative approach as information from the different development stages was obtained to set environmental & economic targets, develop predictive tools and models for process optimization, and to support validation efforts at operating facilities. Over the course of the program, the technology was successfully tested on flue gasses produced from coal, oil, and natural gas combustion, in addition to flue gas produced from refinery applications. Process know-how and operational experience was gained and together with validated data from bench-scale and pilot plant facilities was returned to push process design improvement and the development of predictive models. Currently, the CAP design is also modified and extended into applications involving Urea, Methanol, and Soda Ash Production.While many lessons learned and process improvement opportunities have been extracted from pilot plant and other test facilities, pilot plant results and process modeling studies are still unveiling potential for further improvement. Optimization and integration with the power generation facility occurred in the development phases of several FEED studies for large CCS plants. The CAP design is ready for a demonstration-scale project and now is much improved from the design that was tested originally at laboratory bench-scale. For example, the CAP scrubbing solution is now operated in a non-solids mode where precipitation is not a part of the overall operational strategy and the process flow scheme is now modified and improved from original flow schemes implemented at early pilot facilities to improve performance at reduced cost.This work summarizes the bench-scale, pilot-scale, and validation facility results and offers insights into the lessons learned and effort required bringing the technology into commercialization at an industrial scale. The lessons learned from each of the pilot plants at different sizes are illustrated and the associated impact of the results from each pilot plant in the current CAP product offering is also discussed. A summary of the important results from CAP test facilities including Stanford Research International (SRI), WE energies, EONCAP-Karlshamm, AEP Mountaineer, TCM and GE's pilot facility in Vaxjo, Sweden are presented. Distinguishing features of the GE CAP are provided drawing comparison to open literature versions of ammonia based CO2 capture processes. Evolution of key performance parameters such as energy demand, product quality, solvent strength, process flow scheme, etc., at the different plant sizes are also discussed. In addition, the current state of development for extending the technology into areas where CO2 may be utilized productively are also be addressed in addition to the latest improvement concepts currently being studied on CAP. Finally, the paper will also summarize the advantages of CAP as compared to conventional amine based processes.