Wet coal is dried in a continuous rotary dryer that operates at atmospheric pressure. The chips with a water content of 40 wt% and must leave with a moisture content of less than 15%. Hot air is fed to the dryer at a rate of 11.6 m³ (STP)/kg wet coal. MOIST AIR WET COAL DRYER HOT AIR DRIED COAL 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 0*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) 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 coal is dried in a continuous rotary dryer that operates at atmospheric pressure. The chips with a water content of 40 wt% and must leave with a moisture content of less than 15%. Hot air is fed to the dryer at a rate of 11.6 m³ (STP)/kg wet coal. MOIST AIR WET COAL DRYER HOT AIR DRIED COAL 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 0*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) 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)
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Question
Solve a , b, and c
Transcribed Image Text:Wet coal is dried in a continuous rotary dryer that operates at atmospheric pressure. The chips with a
water content of 40 wt% and must leave with a moisture content of less than 15%. Hot air is fed to the
dryer at a rate of 11.6 m (STP)/kg wet coal.
HOT AIR
MOIST AIR
DRYER
WET COAL
DRIED COAL
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 0*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)
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)
Automate this calculation using Microsoft Excel. The input shall be the
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