Mass emission analyser suits smelters

Analytical Instrumentation & Environmental Monitoring

Analytical instrumentation suppliers

Environmental Control & Monitoring suppliers

Monitoring and sampling systems suppliers

printer friendly version

November 2007 Analytical Instrumentation & Environmental Monitoring

Air pollution regulations restrict the allowable stack emissions from various industrial facilities. Often, a facility will need to measure and report the emissions of multiple pollutants being emitted by their process. Under many compliance regulations, it is not adequate to simply know the concentration of these pollutants in the stack gas emissions. Often, a facility is required to monitor and report the individual mass emissions (eg, lb/hr, kg/day, etc) of their processes.

In order to accurately monitor mass emissions, an analyser must be capable of accurately and reliably measuring the various pollutants of interest while simultaneously measuring the stack gas velocity. This feat is made all the more difficult as the stack gas is typically hot, saturated with moisture, and dirty.

Ametek's 910 mass emission analyser uses the 920 stack gas analyser for the analysis of SO₂ and is suitable for use on smelter stacks. It maintains the sample above the water dew point and analyses on a hot/wet basis. An important fact is that the velocity/flow is measured on an in situ hot/wet basis, and as the mass emission is a product of these two values, the measurement base must be the same.

This method of extractive analysis is commonly referred to as hot/wet analysis. That is, the sample is extracted from the process and kept above the sample dew point throughout the sample transport and analysis. There is no dilution or drying of the sample, keeping the sample above the dew point not only refers to water but also to acid dew points, the sample system is capable of maintaining a sample temperature of up to 180°C or removing the acid at the SCU. This means sample integrity is maintained and any plugging or fouling is minimised.

The 900 Series analysers use hollow cathode lamps, which emit characteristic lines of UV radiation. The positions of these lines are determined by the cathode metal, their wavelength centres being known to a high degree of accuracy. Since these bands are extremely narrow, they facilitate excellent linearity, accuracy and precision in absorbance measurements, independent of variations in bandpass filtering.

Separate reference and measurement paths are part of the photometer design. Light from the source lamp is split into two separate beams through the use of a beam splitter. One beam passes through clean air, the other through the gas sample. Both beams impinge on separate PMTs (reference and measure).

The unique sample cell design made of stainless steel and utilising a folded path configuration, provides for the photometer to be mounted outside of the oven in the electronics cabinet. At one end of the sample cell, a reflector block returns the photometer illumination back to the detector section through a thermal isolation tube.

For more information contact Noel Bauchop, OEN Enterprises, +27 (0)11 675 4447, [email protected], www.oenenterprises.co.za

Share this article:

Analytical Instrumentation & Environmental Monitoring

Mass emission analyser suits smelters

Further reading:

Published by Technews