Reburn is a process where NOx is reduced by reaction with HC fuel fragments as illustrated in Figure 17.1 for a frontwall-fired boiler.
In some cases, LNBs alone may not be able to achieve the NOx emissions to the desired levels in a boiler mainly due to
• The non-availability of LNBs (such as in cyclone firing)
• The performance problems with LNBs (such as in C loss or tubewall wastage) or
• Insufficient NOx reduction
Reburn can be applied to any unit firing any fuel to achieve NOx reductions, typically in the range of 50%–70%. Moreover, it can be integrated with N2-agent injection and other technologies for even greater NOx reduction.