Patent ID: 8561557

Claim:
A system for feeding a primary oxidant to an oxy-fired circulating fluidized bed (CFB) boiler comprising: a plurality of bubble cap assemblies, each bubble cap assembly including a bubble cap, a stem, one or more exit holes, and an inner and outer surface; at least one windbox, wherein the at least one windbox has its own controlled oxidant feed and is connected to each of the stems of the plurality of bubble cap assemblies, and wherein the at least one windbox further comprises at least one manifold; a plurality of pipes, each pipe being located within one of the plurality of bubble cap assemblies, each pipe having an open end that is located at, or below, each of the one or more exit holes of each of the plurality of bubble cap assemblies and each pipe being connected at an opposite end to the at least one manifold contained within its respective windbox; a first controlled oxidant feed delivered independently to the at least one windbox, through the stem of each bubble cap assembly and through the one or more exit holes of each bubble cap assembly into the CFB and having a concentration of oxygen by volume not exceeding 28% oxygen by volume; and a second controlled oxidant feed delivered independently through the at least one manifold, to the plurality of pipes and into the plurality of bubble cap assemblies wherein it mixes with the first controlled oxidant feed and exits through the one or more exit holes of the bubble cap and having a concentration of oxygen by volume of at least 28%; wherein the direction of the exit of the second controlled oxidant feed from the open end of each of the plurality of pipes in each of the plurality of bubble cap assemblies is oriented in a downward direction.