Volume 54

Hydrodynamics of a Pilot-scale Dual Fluidized Bed Reactor: Cold Model Studies Yongtie Cai, Preston Tan, Wen Liu

Abstract

The calcium looping (CAL) process is a cost-effective method for post-combustion CO2 capture, using CaO as a sorbent in the carbonator and CaCO3 for CO2 regeneration in the calciner. A pilot-scale cold model dual fluidized bed (DFB) reactor system was constructed at the Waste-to-Energy Research Facility (WTERF) at Nanyang Technological University (NTU). This system includes a bubbling fluidized bed (BFB) as a carbonator to capture CO2 from WTERF’s flue gas, and a circulating fluidized bed (CFB) as a calciner to regenerate CO2 for storage. The hydrodynamics of the pilot-scale system
were investigated through a series of cold model experiments. The effects of various operating conditions—such as gas velocities in loop seals, the carbonator and calciner, and solid inventories—on pressure distribution and solid circulation rates were studied. The preliminary objective of these cold model studies was to assess the feasibility of the design for
developing a hot model capable of continuously capturing CO2 from real flue gas. The results indicated that changes in gas velocities caused variations in the pressure profile and axial solid holdup within the system. Gas velocities in the calciner significantly influenced the total solid circulation rate. Stable operation was maintained throughout the system, as determined by the pressure drop between the reactors. These studies contribute to the development of an efficient hot model for carbon capture and lay the groundwork for scaling up the calcium looping process for industrial applications.

Keywords Dual fluidized bed, hydrodynamics, calcium looping, carbon capture, cold model