Abstract for presentation at 14th IUAPPA World Congress

Assessing Discharges to Air from Industry – On the Use of Complex Dispersion Models in a Regulatory Environment

  • Neil Gimson, Kingett Mitchell Limited, New Zealand
  • Roger Cudmore, Kingett Mitchell Limited, New Zealand
  • Clive Heydenrych, Kingett Mitchell Limited, New Zealand

    • The paper presents a method for accounting for time-varying stack emissions in an air-dispersion modelling assessment. This is done in an effort to improve the conservatism suffered by modern dispersion models when assuming a constant emission rate. The CALMET/CALPUFF system is used to assess SO2 discharged from an industrial stack with respect to the NZ National Environmental Standards for air quality. The distribution in time of the emission rate derived from a short period of continuous stack testing is replicated statistically and used as input to a two-year model run. The modelled high end of the SO2 distribution is then a better match to the observed SO2 (when both have background levels included), than the distribution obtained through constant emission rate modelling.
    Although the model results are less conservative using this approach, they still overestimate the SO2 concentration to some extent. Methods for improving results still further are discussed.
    Keywords: CALMET, CALPUFF, National Environmental Standards, randomized emissions, sulphur dioxide.

    Conference Organiser - ICMS Pty Ltd