Ill. Admin. Code tit. 35 § 211.3487
"Low-NOx Adm. Code 217, Subpart T, a type of cement kiln burner system designed to lower NOx controlling flame turbulence, delaying fuel/air mixing and establishing fuel-rich zones for initial combusting, which for firing of solid fuel by a kiln's main burner includes an indirect firing system or comparable technique for the main burner to lower the amount of primary combustion air supplied with the pulverized fuel. In an indirect firing system, one air stream is used to convey pulverized fuel from the grinding equipment and another air stream is used to supply primary combustion air to the kiln burner with the pulverized fuel, with intermediate storage of the fuel. In contrast, in a direct firing system, the air stream used to convey pulverized coal is then directly used as primary combustion air without any intermediate storage of fuel, resulting in more primary combustion air than with an indirect system.
Ill. Admin. Code tit. 35, § 211.3487
Added at 25 Ill. Reg. 4582, effective March 15, 2001