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The specialist for UV-absorbing gases: Defor photometer

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article image Defor photometers

Sick  process automation is expanding its successful range of extractive measurement gas analysers. Defor, the company’s new process photometers, detect gases in the ultraviolet spectral range. The global increase in demands for measurement accuracy in recording harmful emissions and the rising requirements in terms of identifying process gases has led to a greater need for selective gas analysers. Nitrogen oxides, chlorine, hydrogen sulphide and sulfur compounds – many methods of measurement are simply unsuitable for such applications. Defor is the specialist here – even for measuring the smallest concentrations of NO or SO2.

Gases can be identified and analysed by their spectral ‘fingerprint’. The Defor photometer utilises gases’ optical characteristics within the ultraviolet spectral range and analyses up to three measured components simultaneously. There are no cross sensitivities in respect of CO2 or H2O. This too is one of the factors that make it easier to obtain exact measurements in many applications. On gas turbines, in power stations, DeNOx plants and desulfurization units Defor monitors even very small threshold limits.

UV gas analyser to provide measurement of nitrogen oxides:

  • In addition to measuring extremely small NO concentrations, Defor can be simultaneously used to identify NO2.
  • For many emission measurements that means there is no longer any need to use a chemiluminescence detector (CLD) or an NO2 converter.
  • The Defor photometer’s ‘intelligent’ software can output both separately measured concentrations as a NOx total. That reduces capital expenditure and operating costs.
  • As the ideal complement for the monitoring of emission thresholds it is also possible to measure SO2 as a third component in small concentrations.
Additional capacities:
  • Besides measuring gases using UV light, the Defor photometer can also be used in conjunction with other SICK analysis modules – all integrated within one case. Using a paramagnetic O2 sensor and a thermal conductivity detector, for instance, oxygen and hydrogen can also be measured. That increases the possible uses considerably. The chemical and petrochemical industries benefit from this in particular.
  • It is both possible to monitor individual components in production operations, for example chlorine in plastics production, and to identify sulfur components in sulfuric acid production or in natural gas.

Detecting and comparing

The Defor process photometers measure gas concentrations through absorption of UV rays. An electrodeless discharge lamp emits both NO-specific and other wide-band rays. Using interference and gas filters, optimum measurement and comparison wavelengths related to the gas component are then selected inside the thermostatic filter wheel unit. These rays are directed onwards to detectors via the analysis and reference cells.

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