A New Real-Time Isokinetic Dust Mass Monitoring System

A new real-time dust mass monitor is being developed by combining an automatic isokinetic sampling probe with a tapered-element oscillating microbalance (TEOM). Particulates from a stack are sampled on line through the isokinetic sampler and collected on an astroquartz mat filter of the TEOM detector. The filter is originally excited and oscillated at a low frequency (about 200 Hz). As the particulates deposit on the filter, the mass increase of the filter is reflected in a frequency reduction which is measured in real time and yields directly the collected particulate mass. The TEOM detector normally has a high mass resolution (10/sup -9/ g) and wide dynamic range (10/sup 5/ to 10/sup 6/). It has been desensitized for high particulate loading applications. The integrated monitoring system was tested in a room-temperature wind-tunnel flow with externally injected particulates. Good agreement was obtained between the mass collected through the isokinetic sampling system and the weight loss of the dust feeder in real time.