Optimisation of the Rectisol TM Design with Packing: the Rectisol TM Demonstration Unit

Abstract

The RectisolTM process is used for more than 80% of the gasification projects for acid gas removal. The RectisolTM process is an efficient way to remove sulfur compounds, CO2 and other traces from syngas with chilled methanol as solvent. In order to respond to the customer need for continuous CapEx (Capital Expenditure) and OpEx (Operational Expenditure) improvement, the use of packing to replace trays in the absorber and reabsorber columns seems promising. Nevertheless, as RectisolTM is a process with a large range of operating conditions (Liquid to gas ratio (L/G), temperature, pressure, liquid loads…), the correlations from literature, mostly established for low pressure distillation, should be out of their domain of validity for some sections. This uncertainty leads to increased design margins to ensure the quality of the product gases. In order to have a better understanding of the performance of packings for RectisolTM applications, a demonstration unit has been built and connected to a commercial size RectisolTM unit in order to perform tests with packings. Gas and liquid flows circulating in the RectisolTM Demonstration Unit (RDU) are directly extracted from and returned to the main plant. The RDU generates performance data on the use of packing in the RectisolTM columns of an industrial scale application and significantly improves the understanding of the operating limits.Based on the results of the tests performed on the RDU, optimized design rules for the RectisolTM process with packing have been defined. This new design allows to significantly reduce the CapEx and OpEx compared to the unoptimized design with packing or tray design and has already been applied in industrial scale RectisolTM.