Modelling dispersion of pollutants from the atmosphere from thermal Rovinari

Transcription

1 Modelling dispersion of pollutants from the atmosphere from thermal Rovinari TĂTAR ADINA 1, PĂSCULESCU MIHAI FLORIN 2, PĂSCULESCU DRAGOŞ 3, ROMANESCU ANDREI 4 The Department of Electric and Energetic Systems Faculty of Electrical and Mechanical Engineering University of Petrosani 20 University Street, , Petroşani, Hunedoara County ROMANIA adddina.tatar@yahoo.com 1 mihai_pasculescu@yahoo.com 2 pdragos_74@yahoo.com 3 romanescu.andrei@transelectrica.ro 4 Abstract: - The purpose of this paper is to conduct an assessment of the potential for undesirable effects on the environment and human health and objective analysis on the pollution of SO2, NO2, CO, particulate Rovinari area. Mathematical modeling of the concentration fields was performed for the main pollutants emitted from sources related to the objective using Austal View program. Were considered, the pollutants were associated values for the protection of sensitive receptors likely to be affected (people of the neighborhood). Graphic representation of mathematical modeling results of the dispersion of pollutants was georeferenced topographical maps. Key-Words: - pollutants, dispersion, atmospheric emissions, toxic. 1. General considerations Impact assessment of pollutants discharged into the atmosphere are carried out in two ways: - The emission quantities of pollutants from the combustion gases are compared with the limit values set out in HG 541/2003; - And the dispersion of pollutants in the area surrounding the pollution source, the values obtained are reported in Order No. permissible limit values. 592/2002. Dispersion modeling was conducted under INSEMEX Petrosani.[1] Rovinari Energy Complex is located in the county near the town of Rovinari, 25 km southwest of the city of Targu Jiu, with a total area of 826, m2 and is the main polluter in the area. The main building is located in the middle of it, energy blocks are taking place from west to east. Complex enclosure Rovinari adjoins -E: European Road E 79 -N: Street Rogojelu, Career Tismana -V :Street Rogojelu, township FARCASESTI, village Rogojel -SV: Street Rogojelu, township FARCASESTI, village Rosia Jiu -S: City Rovinari Thermoelectric power stations (CHP) Rovinari, belongs to SC COMPLEX ENERGETIC Rovinari ROVINARI SA main activity is production of heat and electricity. 1320MW power plant capacity is installed and 4x878MWt electrical power output. Inside the plant are operating two large combustion plants (IMA1 and IMA2) with four energy blocks (No. 3,4,5 and 6), blocks 1 and 2 are ongoing demolition and decommissioning. Energy functional blocks are each provided with the following equipment: -Steam-boiler 1035t/h, 192/48,5 bar, 540/540 o C - Steam Turbine 330MW, 180,4 bar, 535/535 o C - Electrical wiring: -Electric generator : 330MW/380MVA, 24kV, 50Hz - Electric transformer : 400MVA, 24/400kV Combustion gases are discharged through two combustion gas fans, axial type, in vertical construction, and discharged into the atmosphere through two stacks of concrete, each connected to two steam boilers of 1035 t / h (no energy blocks. 3 and 4 - No. 2 stack, that no energy blocks. 5 and 6 - stack 3). Steam boilers of 1035 t / h of the CTE Rovinari works with these types of fuel:

2 - Based fuel lignite - Support added fuel to the flame: - Fuel oil - Natural gas 2.Conditions of climate and meteorology The area analyzed is characterized by a temperate-continental with Mediterranean influences, with specific characters lands Plateau hills and valleys of Piedmont, here emphasizing topoclimatele hills, the valley corridor, and those created by human activities. Atmospheric processes and their consequences are characteristic of the area in winter, warm air of SV advectii generated by Mediterranean cyclones, which causes a milder climate with more frequent precipitation as rain and sleet, winter climate phenomena weak in intensity, duration small layer of snow, frost-free interval length of the longest in the country. It appears that winter is mild and moderate summer, the area is generally warmer climate compared with other regions of the country. In autumn, the average temperature in October was greater than the April 1-2 C. After October 20 start of autumn rains season, the temperature remains positive throughout the month of November and quite often the first half of December. Rainfall is unevenly arranged and is characterized by two maxima, one in early summer and one fall. The amount of rainfall varies between 600 and 700 mm. Due to the scale of human activities in the area analyzed (mining and electricity production in power plants), cloudiness is high compared with neighboring regions, the annual average area of around 5.5 to 5.8 tenths, and the annual amplitude of about 3.3 tenths. The highest values of the cloud is recorded from November to March, surpassing the 6.8 to 6.9 tenths, and the lowest from July to September, with values less than 3.5 tenths. In the prevailing wind directions Rovinari are those of the northern sector (N and NE with frequency of occurrence of 30.1% and 22.8% respectively). The area wind speeds are low and very low in 75% of cases (speeds below 2 m / s). The frequency of moderate wind (speeds between 3-6 m / s) is 15% and relatively strong wind is 10%. The wind direction, average speeds are generally less than 3 m / s. N-NE direction is accompanied by the highest wind speeds of 3.25 m / s and SSW direction from the lowest 1.11 m / s. In describing the dispersion of pollutants in the atmosphere must be taken into consideration two fundamental aspects: -Meteorological processes occurring at local and regional meteorology Boundary Layer and distribution or concentration produced by large sources of pollution The study examines the dispersion of pollutants in the atmosphere are the effect of two processes: - Spread it self, in the wind and other meteorological parameters - Dispersion of pollutants in the atmosphere, complex process that depends not only on meteorological factors, but also geographical, etc. specific source. Pollutants persist in the atmosphere because of two contradictory phenomena: continuous uncovering of impurities, which tend to charge the atmosphere with different amounts of dust and gas, which opposes diluting their diffusion in large masses of air. Among the meteorological factors that determine the dispersion of pollutants, wind borders are characterized by direction and speed, and thermal stratification of the atmosphere. Wind direction is what determines the direction of travel of the mass of pollutant. The concentration of pollutants is maximum wind axis and decreases substantially with distance from it. If high sources, diffusion of pollutants does not occur as soon as they leave the chimney. Because of its speed jet of gas output, the difference in temperature between the exhaust gas and environmental pollutant to the upward movement will continue to lose their initial velocity and its temperature equals that of the environment. Another crucial parameter is the turbulence in the diffusion of pollutants that is intimately linked to the vertical structure of air temperature.. This condition determines the stability of the atmosphere which, in turn, generates the vertical movements of air. Changes in air temperature depending on pressure and thus the height is an important factor involved in the movement of air masses and thus the spread of polluting the atmosphere. Modelling dispersion of pollutants for thermal power Rovinari surrounding areas is accomplished by using a specialized program. Austal View program allows modeling of dispersion of pollutants released one or more sources, and also made a diagram of the existing situation and a forecast of ethnic scenarios proposed by the operator. Data entry software considered: - Select the source area of manifestation of dust and gas - Represent the position source depending on its coordinates on the plan selected - Location of targets, namely receptor (building height and form) - Establishment of grid computing the dispersion - Technical parameters of the source of pollution (H, S)

3 - Aerodynamic parameters of the effluent gas (effluent flow, mass flow pollutants, air speed) - Status of the source parameters (T, W) - Climatic parameters (T, ambient air speed and direction of prevailing winds) - The nature of the pollutant (40 pollutants in the form of dust and gas) - Concentration of pollutant - Characterization of land monograph. Weather data required for plotting the emission of pollutants by Austal View program were obtained from GJ-02 station - located in the town of Rovinari and industrial concerns: temperature, precipitation, wind direction and speed, relative humidity, pressure, solar radiation. Gorj data provided by EPA, the average wind speed in November 2010 is m / s(maximum wind speed is 2m / s), average temperature is C( maximum temperature is 15 o C), and the predominant direction is from N-NE. Appropriate wind zone is shown in Fig.1 Fig.1 Roza appropriate wind zone Rovinari (November 2010 In November 2010, during the impact survey was carried out on air, worked three energy blocks (3, 4, 5), power unit No. 6 is being repaired. As a result of modernization and repair works carried out, dust emissions in the atmosphere have declined in the flue gas concentration (as selfmonitoring results) for all boilers hovering below the project Results of determination of gas concentrations in the flue gas in November 2010 are presented in Table 1. Table 1 Gas emitted from thermal Rovinari-Nov O2 % NO2 mg/n m 3 CO mg/n m 3 SO2 mg/nm 3 Temperature [ 0 C] Pollutant No. 3 12,12 446,33 86, ,75 128,63 No. 4 11,46 465,06 84, ,69 168,18 No. 5 11,28 460,81 205, ,41 134,43 Media Center 11,62 457,40 125, ,28 134,43 To model the dispersion of pollutants in the atmosphere are taken into account the parameters of the emission source characteristics: -Thermal-Rovinari fall within the large combustion installations with a rated thermal input greater than 500 MW -Dimensions of the two existing chimneys, which are part of the resistance structure of steam are: - Physical height H = 220 m; - Top diameter Ф = 8.8 m. - Flue gas flow: 1600Nm 3 /h Source coordinates were determined : X = m; Y= m Emission limit values for combustion plants with a rated thermal input greater than 500 MW and 6% O2 content in flue gases related to the emission limit values according to GD 541/2003.[4] We have chosen three points up with the following coordinates: MNT1: X=18289,46m; Y=127,36 m MNT2: X=10948,73m; Y=16702,32 m MNT3: X=11984,83m; Y=12379,58 m. Graphic representation of mathematical modeling results of the dispersion of pollutants of concern was the 1: scale georeferenced topographic maps. The calculations were carried out in a grid with dimensions 20 km x 20 km and 400 m up the main characteristics of pollutants (SO2, NO2, CO, dust) emitted from stationary sources of combustion directed the CTE Rovinari. Interpretation of mathematical modeling results achieved under MAPM Order No 592/2002. The modeling results are observed values for concentrations of pollutants close to zero and MNT2 MNT1 monitoring points and the choice of these points is not relevant for the analysis of the dispersion. Given the wind, wind speed and prevailing wind direction, dispersion is the S-SW and is appropriate to the location of a monitoring point in the direction MNT3 pollutant cloud. The Concentration of pollutants is maximum wind axis and decreases substantially with distance from it. If high sources, diffusion of pollutants not does occur as soon as they leave the chimney. Maximum concentration values are placed in the direction of the pollutant cloud. Overlapping areas above objectives can be determined izocinetism region most affected by pollutants emitted by energy blocks from the thermal Rovinari. Also dispersion maps were made and have been determined and the monthly average values of concentrations of SO2 (Fig. 2) and NO2 (Fig. 3) in ambient air.[5]

4 Fig.2 Graphical representation of the dispersion of the daily average concentration of SO2 for emission source Fig.3 Graphical representation of the dispersion of NO2 daily average concentration for the emission source 3.Conclusions It is noted that for those two pollutants, the pollutant to a bell shaped distribution with maximum concentrations inside these concentrations and the value decreases outwards. Following dispersion map shows that pollutant pollutant cloud covers S-SW direction to the source of pollution. GJ-2 Rovinari station, which continuously monitors air quality in the town of Rovinari, making the combined contribution of several sources, no excendances of the SO2 and NO2 concentration in November 2010, the average wind speed is m / s ( 2m / s speed), and average air temperature is C (15 full month). SO2 pollution In November 2010, concentrations of SO2, in the three blocks Rovinari Energy's power plant exceeds the emission limit value laid down in the GD 541/2003. The mean concentrations of SO2 emission from each boiler is less than ( No. 3), ( No. 4), ( No. 5) times the emission limit value (400mg/Nm3) The highest value of SO2 emissions from power unit No. 5 was recorded.. The attached graphic representations can be seen that imissions SO2 emissions of pollutants generated by the Energy Blocks 3,4,5, exceed the limit. Cloud of pollutant concentration peaks of 151 mg/m3 to 2000 m distance objective, and covers an area of 1600 m2. Comparison of mathematical modeling results at Order No. 592/2002 MAPM is found that the maximum concentration SO2 is less than 1.20 times the limit value for human health protection. [2],[3] Surface area of 3600m2 in the direction S at a distance of 1200m over the target under the influence of a concentration range ( ) mg/m3, exceeding the maximum permissible concentration (0.8 to 1.20) times. The largest area of the map is covered by cloud pollutant concentration does not exceed the maximum permissible concentration (Fig.2). NO2 pollution In November 2010, concentrations of NO2, the three blocks Rovinari Energy's power plant emissions do not exceed the limit value laid down in HG 541/2003 (500mg/Nm3). Mean concentrations of NO2 emissions from each boiler is small, representing 83% ( No. 3), 93% ( No. 4), 92.1% ( No. 5) of the emission limit value (500 mg / Nm3).. It is noted that the highest values of dust concentration axis extending to S wind. The attached graphic representations can be seen that imissions NO2 emissions of pollutants generated by the Energy Blocks 3,4,5, are within the range (0-87) mg/m3. Concentration (50-87) mg/m3 spans 400m distance near the site immediately to the east from the distance of 1200m to S comprising an area of 8800m2. The biggest stretch a cloud of pollutant concentration is less than 10 mg/m3 and stretches to the southwest (Fig.3). References: [1] INSEMEX Computer modeling of the dispersion of dust from dust and gas stations for fans of the Jiu Valley mining operations, Petrosani, 2010 [2] Order MAPM nr.592/ to approve the norm on the limit values, threshold values and evaluation methods of sulfur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter PM10 and PM2.5, lead, benzene, carbon monoxide and ozone in

5 ambient air, published in Official Monitor no. 765/ [3] SC.EPC CONSULTANŢĂ DE MEDIU SRL, Study on dispersion of pollutants emissions of sulfur dioxide, nitrogen oxides and particulates (PM10) emissions from stationary sources of SC Complex Energetic Rovinari SA, Bucharest, 2010 [4] S.C. ISPE SA, Study Environmental Impact Assessment, Bucharest, 2008 [5] STAS 11103/78 Air purity. Determination of Suspended Powder [6] Tatar Adina -Milena, Modelling dynamic processes in the atmosphere in Report no. 3, University of Petrosani, 2010 Recent Researches in Manufacturing Engineering