Nicolae AJTAI, Zoltán TÖRÖK, Dan COSTIN, Horaţiu ŞTEFĂNIE, Alexandru OZUNU

1. PRELIMINARY RESULTS OF MODELING AND MONITORING OF SO2 EMISSIONS FROM ROVINARI LARGE COMBUSTION POWER PLANT IN SEPTEMBER 2010 Nicolae AJTAI,Zoltán TÖRÖK, Dan COSTIN, Horaţiu ŞTEFĂNIE, Alexandru OZUNU Babeş-Bolyai University Cluj-Napoca, Faculty of Environmental Science and Engineering 30 Fântânele St., 400294 Cluj-Napoca, România, Tel: 004-0264-307030; Fax: 004-0264-307032, e-mail: nicolae.ajtai@ubbcluj.ro Monitoring of SO2 with HORIBA APSA 370 ISCST3 AERMOD dispersion model: AERMOD View is an air dispersion modeling package which incorporates the following U.S. EPA air dispersion models into one integrated interface: AERMOD, ISCST3 and ISC-PRIME. These US EPA air dispersion models are used extensively to assess pollution concentration and deposition from a wide variety of sources. SO2 dispersions were run in a single ISCST3 configuration. The Industrial Source Complex Short Term (ISCST3) model is a Gaussian plume dispersion model that predicts air concentrations around point or area sources using emission rates (flux) and meteorological conditions as model inputs. ISCST3 is applicable for estimating ambient impacts from point, area, and volume sources out to a distance of about 50 kilometers. Abstract: This paper presents the preliminary results of SO2 dispersion modeling of emissions from Rovinari large combustion power plant using ISC AERMOD software, specialized in modeling of gas dispersion. Also the paper compares the results of the modeling with the real-time measurements made with ground based point monitors during RADO field campaign in September 2010, at Rovinari, Gorj County in South-West of Romania. In this part of Romania, the sulfur dioxide emissions have a high rate compared with other parts of the country, mainly because of the major combustion power plants from Rovinari and Turceni which use low quality coal in their processes. Air quality models use mathematical and numerical techniques to simulate the physical and chemical processes that affect air pollutants as they react and disperse in the atmosphere. Based on inputs of meteorological data and source information like rate emissions and stack height, the models characterize pollutants emitted directly in the atmosphere. ISC AERMOD is a complete and powerful air dispersion modeling package. Key words: air quality modeling, ISCST3 model, large combustion power plant, SO2 emissions • Technical specifications and input parameters: • Technical parameters of stack 3 (operational): • altitude above sea level : 161.85 m • release height: 220 m (stack height) • calculated SO2 emission rate: 11742 g/s • gas temperature at release: 146 deg C • stack diameter: 12 m at base, 8.8 m at top • gas velocity at release: 5.2 m/s • gas release rate: 10672 m3/s wet gas / 9011m3/s • dry gas • Meteorological data: • temperature • atmospheric pressure • wind speed and direction • cloud cover and cloud height • Topographic data was inputted using GTOPO30 Global Topographic Data • Results and discussions: • SO2 concentrations were monitored during 04-13 September using the HORIBA APSA 370 monitor. High 24 h averaged concentrations were measured on the 8th, 12th and 13th of September: 126.64 μg/m3 on 08.09.2011 • 33.62 μg/m3 on 12.09.2011 • 23.37 μg/m3 on 13.08.2011 • Simulations were performed over the whole period in which ground-based measurements were made. Meteorological data sets were inputted for the above mentioned time frame. • Due to the limitation introduced by the hourly retrieval of meteorological measurements, only 24h averaged simulations were performed. The output of the model are iso-concentration maps for the days with the first three maximum calculated concentrations in the point where the HORIBA APSA 370 measured during that time: • 1st highest concentration - 579.80 μg/m3 on 12.09.2010 • 2nd highest concentration. -149.60 μg/m3 on 08.09.2010 • 3rd highest concentration - 76.64 μg/m3 on 13.09.2010 • Rovinari Large Combustion power Plant (LCP): • Large combustion plants are defined by the Directive 2001/80/EC of the European Parliament and of the Council of 23 October 2001 on the limitation of emissions of certain pollutants into the air from large combustion plants. LCP are defined as technical apparatus in which fuels are oxidized in order to use the heat thus generated with a rated thermal input equal to or greater than 50 MW, irrespective of the type of fuel used (solid, liquid or gaseous). • The Directive purpose is to limit the amount of sulfur dioxide, nitrogen oxides and dust emitted from large combustion plants each year. It encourages the combined production of heat and electricity (cogeneration). • The Rovinari power plant use as coal source the lignite exploited in the Rovinari -Tismana coal field near the power plant. The lignite is a brownish-black, low-rank coal, with a heating value between 1664-2456 kcal/kg. Coal naturally contains sulfur, and when coal is burned, the sulfur combines with oxygen to form sulfur oxides. The Rovinari power plant use as fuel a mix formed from 92 % coal and 8 % fuel oil. • The lignite used at Rovinari power plant has the following properties: • heating value: 1664-2456 kcal/kg • Sulfur: 1-1, 5 % • Carbon: 15-30% • Hydrogen: 1.5-2.5% • Oxygen: 8.9-12.2% • humidity: 38.20-47.18% • ash: 11.8-25.4% • fuel oil (sulfur concentration of 1%) Fig. 424h average – 12.09.2010 Fig. 2 24h average – 08.09.2010 Conclusions: The study compared the SO2 data from in-situ measurements with simulations performed for the Rovinari area using the emission rate of the Rovinari LCP. In-situ measurements detected high concentrations (24h average) on the 8th, 12th and 13th of September. Modeling results (24 h average) outputted the first three highest concentrations on the 12th, 8th and 13th of September. The model agrees well with the data retrieved on 8th and 13th of September (Fig. 2 and 3) but shows a significant discrepancy for the 12th of September, measured concentrations reaching ~33 μg/m3, while modeling results indicate a concentration of ~580 μg/m3. This difference can result from the lack of accuracy of the meteorological data inputted in the model, or the model itself. Fig.3 24h average – 13.09.2010 Future work: The future work will be focused on obtaining an emission rate from the UV Ground-based imaging camera EnviCam data collected in Rovinari, and compare the results obtained from simulations with the two emission rates. • Acknowledgements: • We wish to acknowledge RADO – STVES 115266 Project, funded by the Norwegian Government and ANCS Romania • This paper was realised with the support of EURODOC “Doctoral Scholarships for research performance at European level” project, financed by the European Social Found and Romanian Government. Fig. 1 General scheme of the power plant