Exploratory Design Study on Reactor Configurations for Carbon Dioxide Capture from Conventional Power Plants Employing Regenerable Solid Sorbents

Abstract

Preliminary commercial designs were carried out for a fluidized bed as a CO2 adsorber and a moving bed as a CO2 regenerator. Reverse engineering methodology was employed on the basis of a commercial 500 MW supercritical PC power plant whereby the boundaries required for a particular reactor design and configuration could be set. Employing the proposed moving bed for regenerator is, however, not promising because of poor heat transfer, evolution of CO2 during regeneration, and high pressure drop when small particles are used. If regeneration kinetics is as slow as reported in tens of minutes, the bed height can be quite high and the reactor can be quite costly. In its place, a so-called assisted self-fluidization bed with embedded heat transfer surface was proposed. Theoretically, there is no reason why the fluidized bed cannot be successfully designed and operated both as an adsorber and a regenerator under proper adsorption and regeneration kinetics. Recent publications, where fluidized beds, circulating fluidized beds, or a combination of them were employed both as an adsorber and a regenerator, were cited. Staging may not be necessary employing the fluidized bed technology because of the capability to control reaction temperature at the optimum operating temperature through embedded heat transfer surface in the fluidized beds. Even if the staging is necessary, the implementation of staging in fluidized beds at ambient pressure and moderate temperature is relatively easy and with minimum cost penalty. Example designs are presented.