Application of liquid desiccant dehumidification to amine-based carbon capture systems

Abstract

Liquid desiccant-based dehumidification with water recovery is an effective and robust method to remove excess moisture from process gas streams and recover relatively high quality product water. A study was undertaken to determine if desiccant-based technology could be applied to the benefit of an amine-based CO 2 capture system since the addition of CO 2 capture to a coal-fired power plant can significantly increase the plant's consumptive water use. Test data with a pilot flue gas moisture recovery system are presented to illustrate the characteristics of the process, including the water recovery potential, product water quality, and thermal energy consumption. The process is then evaluated theoretically under conditions typical of a monoethanolamine-based CO 2 capture process. The analysis indicates that there is less opportunity for moisture recovery compared to a plant without CO 2 capture because of the cooler processing temperatures associated with CO 2 absorption and stripping. However, a desiccantbased dehumidification system might be useful as a heat-driven moisture management tool since desiccant-based moisture removal is more effective than dew point cooling for a given heat rejection temperature. Dehumidifying the CO 2 product stream prior to compression might offer incremental power consumption savings compared to other options of moisture vapor management.

State-of-the-Art Technologies on Low-Grade Heat Recovery and Utilization in Industry

“…To enhance heat and mass transfer between desiccant solution and air, multi-stage LDSs have been proposed by [37], which operates in a cascade way to cool the solution in multiple stages when it flows through more than one absorber. Moreover, a pilot study has been carried out in power plants to investigate an LDS application, which integrates with a CO 2 capture system for moisture recovery [38]. Recently, vertical and horizontal discharge dehumidifiers, fiberglass packed regenerators and small packaged dehumidifier-regenerator commercial LDSs have been made available by Alfa Laval Kathabar [39].…”

A Physicochemical Study of Cost-Effective Liquid Desiccants for Use in an air conditioning systems

“…In the liquid desiccant systems (LDS), the desiccants are specific chemicals that can capture moisture from humid air. They provide a level of vapour pressure lower than water displays at the same temperature, allowing air that moves through this lower pressure solution to become dehumidified [7]. Depending on the concentration and temperature, liquid desiccants can also achieve equilibrium with air at a fixed humidity level [8].…”