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Vronay Completes Emissions Optimization Testing July 20, 2007

Vronay Engineering Services of La Jolla, California and Malcolm Pirnie of White Plains New York completed an ambitious emissions optimization and compliance test program for the City of New York, Department of Environmental Protection at the North River Water Pollution Control Plant in Harlem.

The test program consisted of the optimization of two each of two different models of medium-speed, reciprocating, internal combustion engines which are fueled by varying fractions o diesel fuel, methane-digester gas and natural gas.

The specialist mobile testing laboratory, Spectral Insights, LLC of Durham, North Carolina performed the measurement of all criteria pollutants as well as carbon pollutants such as formaldehyde which are currently listed as Hazardous Air Pollutants (HAPS) by the US EPA. Dr. Jeff LaCosse, PhD, President and Principal Scientist of Spectral Insights was responsible for collecting the measurements of all pollutants using Fourier Transfer Infrared (FTIR) spectroscopy in lieu of other measurement methods which have found to offer less accurate results. 

In contrast to previous emissions tests at this facility, the Vronay lead team installed advanced instrumentation to directly measure with a known accuracy shaft torque, fuel flow (gas and liquid) and combustion airflow. The direct measurements were crosschecked using carbon balance and oxygen balance techniques. Interestingly, it was found that previous test efforts had underestimated the engine airflow by as much as 15-20% while at the same time underestimating the actual engine brake Horsepower. As a result, while ultimately the values of the specific emissions changed little from previous source tests performed at the facility, the route to optimization differed.

The total test program consisted of two-weeks of optimization testing and one-week of compliance assurance testing in which representatives from the New York State Department of Environmental Conservation and the NYC DEP were invited to attend.

The results found all engines were able to comply with NOx RACT standards as required by the facilities operating permit.

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Taking a break from the heat of the engine room. The Test Team L-R: Dr. Jeff LaCosse, PhD and Danny Harrison of Spectral Insights LLC, John Vronay, P.E of Vronay Engineering Services, Ms. Deborah Caston, Malcolm Pirnie and Faeeza Khan Vronay, Vronay Engineering Services.


View of testing during optimization phase of one pump-drive engine. Measurement of shaft torque was performed by use of a custom fabricated, multi-element strain gage collar. Special 1% accuracy, temperature compensated volumetric flow meters were used for fuel oil supply and return flows. All measurements were recorded by a high-speed, PC based data acquisition system designed by Vronay Engineering Services.


John Vronay and Kit Liang, Project Manager for Malcolm Pirnie, discuss test.   Temperatures in the engine room near the operating engines often exceeded 110 degrees F and 80% RH during the mid-July testing in New York City.