IN-DUCT SELECTIVE CATALYTIC REDUCTION OF NOX

THE CONVENTIONAL CONTROL DEVICE FOR NOX EMISSIONS FROM STATIONARY SOURCES AT 90% REMOVAL EFFICIENCY IS THE SELECTIVE CATALYTIC REDUCTION (SCR) SYSTEM. CONVENTIONAL SCR SYSTEMS RELY ON MONOLITHIC CATALYSTS; THESE CATALYSTS OFTEN PRESENT NEARLY ONE-HALF THE CAPITAL INVESTMENT. IN RECENT YEARS, EUROPEAN REGULATIONS HAVE PROMPTED DEVELOPMENT OF IN-DUCT DUST INJECTION CONTROL PROCESSES FOR CERTAIN GASEOUS EMISSIONS. THESE IN-DUCT SYSTEMS HAVE BEEN DEMONSTRATED TO PROVIDE LOWER CAPITAL AND OPERATING COSTS THAN ALTERNATIVE SYSTEMS. IN THE PHASE I RESEARCH, THE TECHNICAL FEASIBILITY IS TO BE DEMONSTRATED OF AN IN-DUCT SCR CONTROL PROCESS FOR NOX CONTROL FROM GAS-FIRED STATIONARY SOURCES. FROM PRELIMINARY LABORATORY EXPERIMENTS, THIS IN-DUCT SCR TECHNOLOGY APPEARS ABLE TO UTILIZE HIGHLY ACTIVE, SMALL PARTICLE SCR CATALYSTS TO ACHIEVE REMARKABLE REACTOR PRODUCTIVITY, WITH SPACE VELOCITIES OF APPROXIMATELY 1,000,000 HR(-1). THE PROCESS REDUCES INTERNAL CATALYST DIFFUSION LIMITATIONS, THEREBY CAPTURING THE INHERENT CATALYST ACTIVITY. THE IN-DUCT SCR TECHNOLOGY HOLDS PROMISE OF APPROACHING THE LOW LIFE-CYCLE COSTS OF NOX CONTROL THROUGH NON-CATALYTIC UREA INJECTION, WHILE ACHIEVING THE HIGH NOX REMOVAL EFFICIENCIES OF CONVENTIONAL CATALYTIC SCR SYSTEMS. AMMONIA SLIP MAY ALL BE MORE EFFECTIVELY CONTROLLED.