Adage Automation is one of the leaders in the Gas Analytics for Cement Process and is amongst the few manufacturers of kiln inlet systems in the world. ABHIJIT CHATTERJEE speaks about some of these analysers.
Indian cement plants have undergone major changes in the recent past primarily for process improvement and reduction in the emissions. Growth of any nation depends on the success story of certain key industry sectors and cement is one of them.
With installations of gas analyser systems in the cement Industry domain across 40 countries around the world, Adage enjoys a leadership position in the Indian cement Industry in terms of market share and innovation.
Today, there are two major types of DeNOx processes known in industry: the Selective Catalytic Reduction (SCR) and the Selective Non-Catalytic Reduction (SNCR). SCR DeNOx installations are common for large scale combustion plants like coal fired power utilities, whereas SNCR technology can often be found in large to mid-size cement plants and incineration plants. LDS 6 insitu Laser Gas analyzers can be used for optimisation of either technology.
The SNCR process
In the SNCR process, usually ammonia (NH3) or urea (CO(NH2)2) is introduced to the flue gases in the hot combustion zone where the reduction of NOx takes place spontaneously. Depending on the type of the reducing agent used, the SNCR process is usually operated in the temperature range of 800 to 950 °C. At temperatures below the optimum temperature, the reaction rate is too slow, resulting in an inefficient NOx reduction and high ammonia slip. Above the optimum temperature, the oxidation of ammonia to NOx is getting significantly high and the process tends to produce NOx instead of decreasing it.
As combustion processes normally show fast and considerable changes in the temperature distribution and the composition of the flues gas, the efficiency of the SNCR- DeNOx process is strongly dependent on the temperature and NOx distribution in the reaction zone.
At constant NOx level behind the reaction zone, the NH3 slip is a strong indicator of the current reaction conditions.
Ammonium Bisulphate formation
Optimising an SNCR process by controlling the NH3 slip means:
About the author:
Abhijit Chatterjee, Managing Director, Adage Automation Pvt Limited.