CEM - Abstract

Abstract Information :

A number of significant particle emission sources are not currently reliably monitored due to the particle size emission spectrum that they produce. These sources include diesel gensets, ships and some waste combustion units. Emissions from these sources are typically dominated by ultrafine particles below 0.2 µm due to lack of large ash deposits in the used fuels and ultrafine particle production through incomplete combustion. Current commercial continuous emission monitor technologies do not detect ultrafine particles. Optical light scattering detection efficiency drops dramatically below 0.1-0.5 micron particle size as particles are below the light wavelength. Triboelectric method detection efficiency for ultrafine particles is extremely low as ultrafine particles will not impact the triboelectric probe, but rather just follow the flow streamlines around the probe. Opacity measurement is only effective if ultrafine particle concentration is extremely high and resulting smoke starts to reduce the intensity of light that passes through the plume. In addition to the sensitivity issues, the optical system response is also dependent on the particle size distribution and gravimetric calibration is only valid for a specific size distribution. Dekati Ltd. has developed new technology to measure the number concentration of ultrafine particles. This technology was originally developed to measure vehicle exhaust particle number concentration in Periodic Inspection and Testing (PTI) of diesel vehicles according to legislation that is currently rolling out in Netherlands, Belgium and Germany and will be subsequently adopted in several countries globally. The developed technology is based on combining diffusion charging with diffusion collection of particles. Diffusion charging efficiency increases with increasing particle size whereas diffusion collection efficiency decreases with increasing particle size, thus resulting with particle size independent response with the right design of charger and collector. As the response is size independent it is only dependent on particle number concentration. The technology has been deployed at the moment in two configurations, as an OEM sensor called electrical particle number counter (ePNC) and as a full independent instrument called mobile particle emission counter (MPEC+). In this work, we will present the verification of the developed technology in terms of particle counting efficiency, linearity and sample conditioning. In addition we will present results from measurement different emission sources and take a look at requirements for integrating this technology for the purpose of continuous emission measurements