Evaluation of the Dispersion Model in a Refinery, Lujan De Cuyo

Abstract

Environmental Management System faced by Repsol YPF has implicating the installation of dispersion models of pollutants in the industrial pole of Mendoza. For this utilization with more complex objectives (for example: environmental impact studies, comparison with procedures of quality of the air, etc.) is necessary to confirm the predictive capacity of the model. The used method was to compare the results of model with monitoring data during the same period. It must be emphasized that the credibility of the confirmation requires a top quality in all the data used in the comparison, that is to say in monitoring data, emission and meteorology. The duration of the evaluation of the model was for a year. Introduction The use increasingly frequent of programs of pollutants dispersion gaseous in the industrial activity carried to Repsol YPF to select the program AIRVIRO (versioón2.3O, SMHI IS - 60176 Norrklping, Sweden) to simulate the impact that produces the operation of the Refinery in its influence environment. Said programs are applicable in environmental impact studies, comparisons with procedures of quality of the air, etc. However, these models should be confirmed with monitoring data accomplished in the influence area to determine the predict capacity of them. The program AIRVIRO is a modified Gaussian model. This model permits to calculate the dispersion throughout a straight line in the direction of the wind, using different types of atmospherical stability estimate as of a meteorological station of synoptic type. The gaussian parameters that regulate the lateral and vertical dispersion of the emission plume are taken of the existing bibliography, based in atmospherical stability and knowing the vertical wind profiles and temperature (1). Also, the model, permits to calculate the dispersion throughout paths of the wind, something which means that the plume can follow a bandy distance (can not form complete circles) and this permits to have a heterogeneous winds field in function of the topography and the local ruggedness. Methodology The method to follow is the results comparison of the modelization with monitoring data of the same period accomplished in the influence area of the Refinery Luján de Cuyo of Repsol YPF. It must be emphasized that the credibility of the evaluation requires a top quality of all the data used in the comparison, that is to say, in monitoring data, emission and meteorology. Given the turbulent and stochastic conditions existence, not predictable in each detail, it is necessary to accomplish the comparison during a period sufficiently long for let a data statistics of the model and of the monitoring. Because of this it was determined to accomplish the evaluation during a year (June 1999 - June 2000). The steps followed during this confirmation of the model were:Election of the pollutant to use for the evaluationElection of the technology for the monitoring and the sites where made thisEvaluation of the quality of the meteorological informationEvaluation of the quality of the information of the emissionsEvaluation of the results of the monitoringModelizationEvaluation 1-Election of the pollutant to use for the evaluation: Is taking into account to would be a typical pollutant and that could be measured with not expensive technologies. Furthermore, would have to be able is quantified and be described perfectly in the daily activity of the Refinery. The pollutant that complies with these requirements and it was selected to accomplish the monitoring is the sulfur dioxide (SO2). The standard level (admissible maximum) is 0.03 ppm for 8 hours of continuous exposition (2).