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Division 6.2 Diffuse VOC emissions

United Kingdom

Original text. Later amendments are not shown.

TechniqueDescription
High-integrity equipment

High-integrity equipment includes:

  • valves with double packing seals;

  • magnetically driven pumps/compressors/agitators;

  • pumps/compressors/agitators fitted with mechanical seals instead of packing;

  • high-integrity gaskets (such as spiral wound, ring joints) for critical applications;

  • corrosion-resistant equipment.

Leak detection and repair (LDAR) programme

A structured approach to reduce fugitive VOC emissions by detection and subsequent repair or replacement of leaking components. Currently, sniffing (described by EN 15446) and optical gas imaging methods are available for the identification of leaks.

Sniffing method

  • The first step is the detection using hand-held VOC analysers measuring the concentration adjacent to the equipment (e.g. by using flame ionisation or photo-ionisation). The second step consists of bagging the component to carry out a direct measurement at the source of emission. This second step is sometimes replaced by mathematical correlation curves derived from statistical results obtained from a large number of previous measurements made on similar components.

    • Optical gas imaging methods

  • Optical imaging uses small lightweight hand-held cameras which enable the visualisation of gas leaks in real time, so that they appear as ‘smoke’ on a video recorder together with the normal image of the component concerned, to easily and rapidly locate significant VOC leaks. Active systems produce an image with a back-scattered infrared laser light reflected on the component and its surroundings. Passive systems are based on the natural infrared radiation of the equipment and its surroundings

    • Thermal oxidationThe oxidation of combustible gases and odorants in a waste gas stream by heating the mixture of contaminants with air or oxygen to above its auto-ignition point in a combustion chamber and maintaining it at a high temperature long enough to complete its combustion to carbon dioxide and water. Thermal oxidation is also referred to as ‘incineration’, ‘thermal incineration’ or ‘oxidative combustion’.
    Using the designed gasket stress for flanged joint assembly

    This includes:

    1. (i)

      obtaining a certified high quality gasket, e.g. according to EN 13555;

    2. (ii)

      calculating the highest possible bolt load, e.g. according to EN 1591-1;

    3. (iii)

      obtaining a qualified flange-assembling equipment;

    4. (iv)

      supervision of the bolt tightening by a qualified fitter.

    VOC diffuse emissions monitoring

    Sniffing and optical gas imaging methods are described under leak detection and repair programme.

    Full screening and quantification of emissions from the installation can be undertaken with an appropriate combination of complementary methods, e.g. Solar occultation flux (SOF) or Differential absorption LIDAR (DIAL) campaigns. These results can be used for trend evaluation in time, cross-checking and updating/validation of the on-going LDAR programme.

    Solar occultation flux (SOF)

  • The technique is based on the recording and spectrometric Fourier Transform analysis of a broadband infra-red or ultraviolet/visible sunlight spectra along a given geographical itinerary, crossing the wind direction and cutting through VOC plumes.

    • Differential absorption LIDAR (DIAL)

  • This is a laser-based technique using differential absorption LIDAR (light detection and ranging), which is the optical analogue of radio wave-based RADAR. The technique relies on the back-scattering of laser beam pulses by atmospheric aerosols, and the analysis of spectral properties of the returned light collected with a telescope.

    •