Monitoring Sulfur Dioxide and Nitrogen Oxides through Continuous Emission Monitoring for Compliance to Standards

 Continuous emission monitoring (CEM) ensures that the mandatory reductions for SO2 and NOx under the Acid Rain Program are being achieved. While traditional emission programs have required facilities to meet requirements as to specific emission rates, the Acid Rain Program mandates an accurate report of each ton of emissions for every regulated unit with compliance determined through a process in which a direct comparison of the total annual SO2 emissions reported by CEM and the allowances provided for each unit. Through CEM there is a continuous measurement of pollutants that are emitted into the air from the exhaust gases coming from industries and combustion processes. However, it is not only SO2 emissions that are closely monitored as it includes carbon dioxide (CO2) emissions. In order to comply with CEM, industries are required to provide performance specifications, certification procedures as well as recordkeeping and reporting.

Monitoring requirements for units regulated under the Acid Rain Program

Owners of units regulated under the program should install continuous emission monitoring on their units which should include the following:

·         An SO2 pollutant concentration monitor to monitor SO2 emissions in pounds per hour

·         A NOx pollutant concentration monitor to calculate emissions rate in pounds per million British thermal units

·         A volumetric flow monitor for flow measurement with high levels of accuracy and performance

·         An opacity monitor to measure the percentage of light that can be seen through the flue gas

·         A diluents gas (O2 or CO2) monitor to computer emissions in tons per hour

·         A computer based data acquisition and handling system to collect and record data

Units that are required to measure and report emissions under the Acid Rain Program

·         All existing coal-fired units serving a generator greater than 25 megawatts. All new coal units are required to use CEM for SO2, NOx, flow and opacity

·         Units that burn natural gas may determine SO2 mass emissions by measuring heat input using gas flowmeter and a default emission rate or sampling and analyzing sulfur daily and using the volume of gas combusted. A more efficient process would be to use continuous emission monitoring.

·         Units that burn oil can monitor their sulfur mass emissions using daily manual oil sampling and analysis plus the oil flow meter, sampling and analysis of diesel fuel oil upon delivery plus the oil flow meter, an automatic and continuous oil sampling plus the oil flow meter and the use of SO2 and flow CEMs.

·         Gas-fired and oil-fired based loaded units that are required to use NOx CEMs

·         Gas-fired peaking units including oil-fired peaking units that use NOx CEMs or estimate NOx emissions using site-specific emission correlations and periodic stack testing for verification

·         All gas-fired units that use natural gas for at least 90% of their annual heat input including units burning diesel oil fuel that are exempt from opacity monitoring

·         For all CO2 units that use either the mass balance estimation, CO2 CEMs or O2 CEMs so as to estimate the CO2 emissions

You need good analyzers too for continuous emission monitoring, especially when high levels of some gases threaten the safety at your workplace.
Posted by: Jorge | December 18, 2013, 2:39 pm
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