Cement, Energy and Environment

36 NOx Reduction with High Efficiency SNCR R Lopes and W Kurka Yara Environmental Technologies 1.0 More stringent NOx regulations NOx regulations are becoming more stringent. In India NOx ELVs has gone down to 800 and even 600 mg/Nm3 for new commissioned kilns. For CPP boilers the limit is even going down to 200 mg/Nm³. Cement plants Unit Existing kilns New commissioned Rotary kilns mg/Nm 3 <800 <600 CPP boilers mg/Nm 3 <200 Fig. 1 NOx emission limit values in Indian Cement Industry Yara has been involved in several projects installing new high performance SNCR systems that are able to reduce the NOx down reaching high reductions of sometimes 80 – 90 % with SNCR for rotary kilns and 60-70% for CPP boilers, ammonia solution has to be used. Using urea, reductions much over 50% can in most cases not be reached. 2.0 High performance SNCR Background In the last 20 years the team of YARA has installed deNOx systems (SCR + SNCR) all around the world. In 1997 due to the Swedish emission tax system, the first high efficiency SNCR reducing NOx from 1200 mg/Nm³ down to 200 mg/Nm³ has been installed and is still in operation. With more than 300 references for boiler and kiln SNCR systems and 200 references for SCR system, YARA Environmental Technologies can cover all different aspects of secondary NOx abatement. Out of this YARA can offer a tailor-made solution. Off course the first step in investigation for a NOx reduction project is to check the feasibility of using a high efficiency SNCR solution, which is in most cases possible and the economically more feasible solution. High performance SNCR means:  Possibility of high NOx reduction, up to 80 – 90% is possible.  High chemical efficiency, and the minimization of the consumption of reagent which is the major operational cost for running a cement plant SNCR.  Reliable system with high availability.  High safety standard. 3.0 The SNCR system and its components The following figure 2 is showing the main parts and flow of a SNCR system. Fig. 2 SNCR system