Kiln Continuous Emission Monitoring Systems (CEMS) Relative Accuracy Test Audits (RATA)


Lhoist North America (Lhoist Group)


Pittsburgh, PA

CEC Services

  • Air Quality Compliance Testing Services

Owner Objective

Lhoist Group, a global leader in lime, dolime and minerals, has relative accuracy test audits (RATA) conducted on the lime kiln Continuous Emission Monitoring Systems (CEMS) at the Lhoist facility in Sainte Genevieve, Missouri.

CEC Approach

CEC was retained to conduct the RATA at the Sainte Genevieve facility. Lhoist operates two rotary kilns used in the production of lime. One analyzer system monitors the stack exhaust gases from each of the kilns. The CEMS is designed to automatically switch between the two stacks. The CEMS is equipped with an M&C Products Model XO Custom Panel Switching Controller that allows the analyzer to monitor the emissions from one stack and then switch to the other. The time-sharing arrangement allows for the continuous monitoring of emissions from both kilns utilizing one analyzer system. The controller switches stacks every 7.5 minutes, thus allowing for four samples per hour per kiln. The Data Acquisition System (DAS) does not include the first 90 seconds of the 7.5 minute data, to guarantee the data recorded is from the appropriate kiln. The kiln CEMS are constantly extracting samples from both stacks and the controller directs one sample to the analyzer and the other to the atmosphere. The constant extraction of sample gas from the stacks allows the CEMS to eliminate any response delay of pulling gas through the extraction system.

During the stack testing, the CEMS were operated in single stack mode. This procedure allows for the continuous measurement of stack gas from one kiln. The kiln stacks are equipped with Teledyne Monitor Labs Ultraflow 150 flow rate monitors and the ball mill return air duct is equipped with a Kurz Model 454 FT flow rate monitor with a K-bar-24 probe. The flow rate monitor readings are integrated into the pollutant data acquisition system and reporting database. The purpose of the testing was to demonstrate compliance with the CEMS monitor certification requirements outlined in Performance Specifications 2 and 3 presented in 40 CFR Part 60, Appendix B. Additionally, the annual certification for the California Analytical Instruments (CAI) carbon dioxide (CO2) analyzer was performed. The CAI analyzer was installed as to provide data for reporting required in 40 CFR Part 98. The annual certification of the MAC moisture analyzers was also completed.