entech. WKP Magazine Explosion Simulation – Gas Dispersal Study P a g e | 12 Table 4-3 – Peak contaminant volumes per surface connection w. fans on and off. Velocity and temperature at surface connections did not change during the modelling, indicating that the explosion’s influence on airflow and heat was localised at the source. 4.4 TIME DURATION OF CONTAMINANT DISPERSAL Contaminant dispersal was Simulated at the fasted rate of release, which would see the highest contaminant concentration as the gas front exits the surface connection. Gas dispersal will be affected by fan operation, the alternate routes that gas takes as it makes its way through the underground workings, and the ambient conditions affecting airflow (when fans are off). This can result in multiple minor peak concentrations and take several hours, or even days to clear, if the main fan is switched off for instance. Summer Winter 1. Fan OFF Fan OFF Rise 2 Rise 1 Plant Portal Willows Port. Rise 1 Temp (⁰C) 21.4 21.8 22.9 22.3 14.7 BP (hPa) 971 966 985 975 965 V (m/s) 16.4 0.9 0.4 0.4 0.5 CO (ppm) 2929.3301 582.5932 294.7679 523.5465 160.0842 MM (g/mol) 28 28 28 28 28 mg/mᶟ 3,254.7148 643.0996 330.5481 582.3172 180.8836 g/mᶟ 3.2547 0.6431 0.3305 0.5823 0.1809 Q (mᶟ/s) 390 17.4 9.5 10.6 10.6 g/s 1,269.3 11.2 3.1 6.2 1.9 NO (ppm) 115.9846 23.0110 11.6391 20.6776 6.3202 MM (g/mol) 30 30 30 30 30 mg/mᶟ 138.0729 27.2152 13.9842 24.6415 7.6514 g/mᶟ 0.1381 0.0272 0.0140 0.0246 0.0077 Q (mᶟ/s) 390 17.4 9.5 10.6 10.6 g/s 53.8 0.5 0.1 0.3 0.1 NO2 (ppm) 115.6315 22.9971 11.6356 20.6663 6.3191 MM (g/mol) 46 46 46 46 46 mg/mᶟ 211.0670 41.7048 21.4359 37.7631 11.7302 g/mᶟ 0.2111 0.0417 0.0214 0.0378 0.0117 Q (mᶟ/s) 390 17.4 9.5 10.6 10.6 g/s 82.3 0.7 0.2 0.4 0.1 NH3 (ppm) 77.3231 15.3407 7.7594 13.7850 4.2134 MM (g/mol) 17 17 17 17 17 mg/mᶟ 52.1609 10.2813 5.2829 9.3090 2.8905 g/mᶟ 0.0522 0.0103 0.0053 0.0093 0.0029 Q (mᶟ/s) 390 17.4 9.5 10.6 10.6 g/s 20.3 0.2 0.05 0.1 0.03 2. Fan OFF Units Fan ON Summer Peak Gas Concentrations @Exhaust Points
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