A TESTING PROCESS TO DEFINE ELECTRODE CURRENT WEAR MECHANISMS AND DEVELOP IMPROVED ELECTRODES

COAL-FIRED MAGNETOHYDRODYAMIC (MHD) TECHNOLOGY HAS ADVANCED TO THE STAGE OF TESTING LARGE SCALECOMPONENTS TO DEMONSTRATE THE FEASIBILITY OF THE OVERALL PROCESS FORAPPLICATION AS A VIABLE COMMERCIAL POWER GENERATION TECHNIQUE. HOWEVER, TESTING TO EVALUATETHE FUNDAMENTAL ASPECTS OF ELECTRODE WEAR IS NOT BEING CONDUCTED. IT APPEARS THAT SOME ADDITIONAL UNDERSTANDING OF GAS-SIDE COMPONENT WEAR, SPECIFICALLY ANODE WEAR DUE TO ARC CURRENT LEVELS, IS ESSENTIAL TO ADVANCE DESIGNS OF ANODES THAT CAN WITHSTAND HIGH CURRENT ARCS. EXPERIMENTAL DATA HAVE SHOWN, AND THEORETICAL CALCULATIONS PREDICT, THAT ARE CURRENT VALUES WILL INCREASE FOR COMMERCIAL SCALE CHANNELS. HOWEVER, THERE IS NO EXPERIMENTAL FACILITY TO SYSTEMATICALLY DETERMINE THE EFFECT OF ARC CURRENT ON STATE-OF-THE-ART ANODE WEAR RATES AND DAMAGE THRESHOLDS, EVEN THOUGH THIS PROCESS IS ESSENTIAL FOR IMPROVEMENT OF MHD ELECTRODE LIFETIMES. THE PRIMARY PHASE I OBJECTIVE IS TO SHOW THAT A CAREFULLY CONTROLLED BENCH SCALE TECHNIQUE IS SUITABLE TO ESTABLISHANODE ARC CURRENT DAMAGE THRESHOLDS FOR STATE-OF-THE-ART ANODE DESIGNS AND MATERIALS. THE APPROACH WILL USE A LOW-COST, BUT TECHNICALLY-SOUND, SCREENING-TYPE EXPERIMENT TO DETERMINE DAMAGE THRESHOLDS AND ESTABLISH A FUNDAMENTAL UNDERSTANDING OF ARC CURRENT WEAR PROCESSES IN MHD CHANNEL ENVIRONMENTS. EMPHASIS WILL BE PLACED ON USING THE TESTSCHEME TO REPLICATE ANODE WEAR AND DAMAGE FEATURES OBSERVED IN MHD CHANNELS AND, VIA SYSTEMATIC METALLURGICAL ANALYSIS, DEVELOP A FUNDAMENTAL UNDERSTANDING OF THE WEAR PROCESSES. THESE PROCEDURES WILL PROVIDE CURRENT LIMITATION CRITERIA FOR ANODE MATERIALS AND DESIGNS. SECONDARY OBJECTIVES INCLUDE THE USE OF THIS PROCESS TO TEST ALTERNATIVE, STATE-OF-THE-ART MATERIALS FABRICATION PROCESSES DEVELOPED IN THE ELECTRICAL CONTACT INDUSTRY THAY MAY HAVE HIGHER THRESHOLD ARC CURRENT THAN THE EXISTING MHD CHANNEL ELECTRODE DESIGNS.