(517e) Advanced Solids Flow Sensor Technology for Chemical Looping

Short Abstract

Chemical looping combustion is being developed by the U.S. Department of Energy as a possible technology for heat or power generation with integrated carbon dioxide separation.  Improved sensors and controls are among the technical challenges that must be overcome for the commercial success of chemical looping.   For improved control the chemical looping process, accurate and rapid measurement of key process parameters is required.    A high temperature solids-flow sensor, based on microwave Doppler technology, is being developed to provide online measurement of solids circulation rate.   This paper reports on progress in the development and testing of this sensor technology for CLC conditions.

Introduction

Chemical looping combustion is being developed with support of the U.S. Department of Energy because it has potential for carbon capture with less efficiency penalty than conventional power cycles with post-combustion capture.  [1][2] Chemical looping uses an intermediary, such as a metal oxide, to collect oxygen from air in the air reactor.  The oxidized particles are then transported and to the fuel reactor, where the oxygen carrier particles are reduced.  The product gas stream contains mostly carbon dioxide and water vapor, which be readily separated for carbon capture, utilization and storage.   An inert buffering gas is injected in the process between the reactors to help separate the oxidation and reduction processes.  

One of the challenges for operation of a chemical looping combustion process is the measurement and control of the solids circulation rate.   The circulation rate is important for controlling both heat transfer and chemical reaction processes.   It has been observed to have large variations on a short time scale, in cold flow systems used to model the hydrodynamics.   While the circulation rate may be estimated from pressure drops at various points in the process, this measurement approach is indirect, and has had considerable uncertainty.