Reference no: EM132976634
Question 1. The schematic ventilation circuit (Figure 1) shows the general ventilation distribution for a mine's two kilometre longwall block. The mine has five mains headings (two intake travel roads A and C, one intake conveyor road B and two returns D and E).
1) Calculate the combined resistance of the two maingate airways (A-B)? (Round the result to at least four decimal places)
2) How much air is flowing in the maingate travel road?
3) How much air is in the bleeder heading?
4) Calculate the resistance of the tailgate? (Round the result to three decimal places)
5) Calculate the resistance of the twin returns A* to D? (Round the result to four decimal places)
6) What is the frictional pressure drop in the longwall circuit (A-B-C-D)?
7) What is the pressure drop across the maingate overcasts (A - A*)?
8) Calculate the total resistance of inbye panels (A - A*).
Question 2. Two centrifugal fans are installed in parallel at the top of exhaust shaft of an underground mine to provide fresh air, remove contaminants and maintain an acceptable temperature in the mine workings. The mine has a resistance of R=0.06 Ns2/m8 and requires an air quantity of 150 m3/s. The characteristic curve of the two fans in parallel at 500 rpm is presented in Table 1. The natural ventilation pressure is -100 Pa.
1) Plot the fan in parallel combined fan curve on Figure 2 and label it.
2) Plot the mine's resistance curve (consider natural ventilation) on Figure 2 and label it. What is the two fans in parallel combined operating point?
3) If the two fans are installed in series, what is the combined system operating point? What is the operating point for each fan? (show and label the fan curves on Figure 2)
4) If the mine resistance increases to R=0.12 Ns2/m8, and the speeds of both fans are increased to 600 rpm (installed in series).
a) Plot the current mine resistance curve (consider natural ventilation) on Figure 2 and label it.
b) Plot the current two fans in series fan curve on Figure 2 and label it.
c) What is the current combined two fans in series operating point?
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