Abstract Description: In the United States, utility operators are faced with continuous monitoring requirements under 40 CFR Part 60 New Source Performance Standards. Both natural gas and oil-fired steam generation units over 100,000 mm BTU rated heat input capacity will be required to install gas analyzers and sampling systems that document Nitrogen Oxides mass emission rate on a continuous basis. These continuous emission monitoring systems (CEMS) include heated probes on the stack, heated sampling lines, and other ancillary components such as cylinder gases that require specialists to support and can be expensive to maintain. 40 CFR Part 60 allows for the use of alternatives to CEMS. Predictive emissions monitoring systems (PEMS) are used widely in the U.S. and overseas for 40 CFR Part 60 compliance at a reduced cost with higher data availability. The PEMS consists of a computer and a predictive model along with a compliance data acquisition system. In 2019, the University of Wisconsin replaced five CEMS on large boilers in two steam plants with PEMS. This paper details the efforts involved in building the PEMS models, deployment of the PEMS hardware and software, methods of validation testing for compliance certification, and the ongoing costs results of maintenance and quality assurance of the PEMS. Following certification, the facility conducts biannual relative accuracy audits (RAA) and annual RATA testing, which is comparable to that required of CEMS, however, the PEMS hardware and software is much less expensive to operate than the gas analyzer based CEMS. The deployed PEMS has reduced the total cost of ownership of the continuous compliance monitoring solution for both plants by 50% and has maintained 100% data availability over the first three years of operation.
