(678c) INVESTIGATION OF HYDRODYNAMICS FOR ALSTOM’S LIMESTONE-BASED CHEMICAL LOOPING PROCESS

Chemical looping is a clean-coal technology which utilizes a solid oxygen carrier to provide oxygen to a fuel conversion (combustion and gasification) process.  This breakthrough fuel conversion technology does not require a capital-intensive high power consuming cryogenic air separation unit and is “transformational” in terms of its overall efficiency and cost.  Chemical looping combustion for steam power is the lowest cost technical approach that ALSTOM has identified to date for coal power with carbon capture. 

ALSTOM is currently developing a Limestone-based Chemical Looping Combustion (LCL-C™) technology for power generation utilizing coal.  The limestone chemical looping concept is now in the advanced stages of testing at the 3-MW_TH prototype facility in Windsor, CT; after achieving over 350 hours of operation including 75 hours of self-sustained autothermal operation. Testing  continues at the 3-MW_TH pilot test facility in Windsor, CT; with the goal of addressing technology gaps identified so far, and developing information necessary for further scale-up to 10 to 25 MWe. ALSTOM is concurrently developing Limestone-based Chemical Looping Gasification (LCL-G™), and Hydrogen (LCL-H™) by adaptation of LCL-C™.

As part of the development effort, Cold Flow Modeling (CFM) and Computational Fluid Dynamic (CFD) simulations are being performed to better understand the hydrodynamic behavior of oxygen carrier particles.  The current focus is in evaluating the impact of product gas generation in the reducer (fuel reactor) loop on the performance of the cyclone and the dipleg.

ALSTOM utilized its licensed Barracuda® software to create a CFD model of the 3 MW_TH LCL-C™ pilot facilities.  The CFD model was used to create a baseline comparison to a 3 MW_TH prototype cold flow test at ambient conditions.  Next, the baseline CFD model was adjusted to simulate gas generation in the dipleg.  Gas generation was simulated in an attempt to represent the instabilities resulting from the chemical looping reaction mechanism.  In parallel, ALSTOM utilized their 40 foot tall plexiglass CFM to run similar tests characterizing the phenomena associated with gas generation in the dipleg.  The 40 foot CFM was used to assess possible equipment, or operational modifications to provide solutions to the instabilities.  Results of the CFM, and CFD work are used as a tool to gain insight into the hydrodynamics of the 3 MW_TH LCL-C™ prototype.  This paper presents the simulation results and cold flow modeling data that were generated in association with the activities described above.