Measurements and Modeling of Coal Ash Deposition in an Entrained-Flow Reactor

摘要: MEASUREMENTS AND MODELING OF COAL ASH DEPOSITION IN AN ENTRAINED-FLOW REACTOR Ryan Blanchard Department of Mechanical Engineering Master Science Coal plays a significant role in meeting the world’s need for energy and will continue to do so many years come. Economic, environmental, public opinion are requiring coal derived be cleaner operate more narrow window operating conditions. Fouling slagging heat transfer surfaces continues challenge maintaining boiler availability expanding use available fuels The work incorporates existing information literature on ash deposition into User-Defined Function (UDF) commercial comprehensive combustion CFD code. Results from new submodel code is then compared measurements simulated tube where particle mass deposited size distribution measured. Several model components governing various aspects have been incorporated UDF which has implemented quasi-unsteady Computation Fluid Dynamics (CFD) simulation. consists models impaction sticking, thermal physical properties deposits, unsteady growth effects insulating layers processes. layer allowed transition an accumulation individual particles, sintered layer, finally molten or frozen slag layer. attempts predict deposit thickness, conductivity, emittance. Measurements showed fly sizes that were much smaller than predicted under non-fragmentation assumption. Use fragmentation matched mean diameters well but did not match upper tail inertial takes place. Assuming 100% capture efficiency all particles provided reasonably good agreement with measured rates. observed trend lower rates reducing conditions was captured when gas viscosity calculated using probe temperature.