Wet wood chips are dried in a continuous rotary dryer that operates at atmospheric pressure. The chips enter at 19C with water content of 40 wt % and must leave with a moisture content of less than 15%. Hot air is fed to the dryer at the rate of 11.6 m (STP)kg wet chips. To monitor the performance of the dryer by sampling the exiting chips and determining their moisture content directly would be a cumbersome procedure and almost impossible to automate. Instead, wet and dry-bulb thermometers are mounted in both inlet and outlet air lines, and the moisture content of the exiting chips is determined by a material balance. Moist Air Air, 11.6 m (STP)kg wet chips T(C), T (C) DRYER Wet Chips 19C, 40 wt %water Chips + Residual moisture To monitor the performance of the dryer by sampling the exiting coal and determining their moisture content directly would be a cumbersome procedure and almost impossible to automate. Instead, wet-and dry-bulb thermometers are mounted in both the inlet and outlet air lines, and the moisture content of the exiting chips is determined by a material balance calculator. (STP: Standard Temperature and Pressure is o"C and 101.325 kPa) (a)The hot air stream has an absolute humidity of 0.058 kg moisture/kg dry air and leaves with 0.087 kg moisture/kg dry air, calculate the mass of water in the exiting air per kilogram of wet coal fed. (b)Can the dryer reduce the wet coal moisture to 15%? If the answer is no, suggest the minimum ratio of air to wet coal for the process to be successful. (c) Provide Excel screenshot. Automate this calculation using Microsoft Excel. The input shall be the amount of wet coal to be dried in kg/d and the output shall be the amount of hot air to be fed in m3/d at STP. Use the ratio of air to wet coal in (b)
Wet wood chips are dried in a continuous rotary dryer that operates at atmospheric pressure. The chips enter at 19C with water content of 40 wt % and must leave with a moisture content of less than 15%. Hot air is fed to the dryer at the rate of 11.6 m (STP)kg wet chips.
To monitor the performance of the dryer by sampling the exiting chips and determining their moisture content directly would be a cumbersome procedure and almost impossible to automate. Instead, wet and dry-bulb thermometers are mounted in both inlet and outlet air lines, and the moisture content of the exiting chips is determined by a material balance. Moist Air Air, 11.6 m (STP)kg wet chips T(C), T (C) DRYER Wet Chips 19C, 40 wt %water Chips + Residual moisture To monitor the performance of the dryer by sampling the exiting coal and determining their moisture content directly would be a cumbersome procedure and almost impossible to automate. Instead, wet-and dry-bulb thermometers are mounted in both the inlet and outlet air lines, and the moisture content of the exiting chips is determined by a material balance calculator. (STP: Standard Temperature and Pressure is o"C and 101.325 kPa)
(a)The hot air stream has an absolute humidity of 0.058 kg moisture/kg dry air and leaves with 0.087 kg moisture/kg dry air, calculate the mass of water in the exiting air per kilogram of wet coal fed.
(b)Can the dryer reduce the wet coal moisture to 15%? If the answer is no, suggest the minimum ratio of air to wet coal for the process to be successful.
(c) Provide Excel screenshot. Automate this calculation using Microsoft Excel. The input shall be the amount of wet coal to be dried in kg/d and the output shall be the amount of hot air to be fed in m3/d at STP. Use the ratio of air to wet coal in (b)
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