Stack Dilution probe for CEMs

DESCRIPTION

 

The extractive dilution technique is the most widely used method for continuous emission monitoring of SO2

and NOx it is also ideal for use in monitoring CO, NH3, HCL and other species which low concentration gas

analyzers has been build for. It can also be combined with a zirconium oxide sensor for the continuous

measurement of O2.

 

Theory of Operation

 

The technique is based on extracting a small sample from the stack, removing particulates by a proprietary

filter and then accurately diluting the sample with clean, dry zero air; thus reducing the dew point in order to

prevent condensation of water vapour and acid mist in the sample lines. The diluted sample is then

conveyed in unheated umbilical lines to the base of the stack where it is analyzed by high precision gas

analyzers. Due to the high sensitivity of these analyzers, dilution doesn’t influence measurement accuracy.

In fact, accuracy is improved over other systems since water vapor cannot condense and remove

compounds such as SO2, NO2, NH3 and other water soluble gasses.

 

 

 

Calibration

 

Calibration of the system is achieved effectively by sending span or zero gas directly to the stack and directly

into the front of the probe filter. This effectively displaces the stack gas, so that the entire system samples

the calibration gas. This scheme provides a true calibration of the full system under working conditions.

Because excess calibration gas is vented to the stack, even stack pressure effects are tested. This method

of calibration eliminates the need to know the dilution ratio as the analyzers are adjusted to read the span

gas concentration directly.

Detailed product information: