In a mechanical coal-washing process, a portion of the inorganic sulfur and ash material in the mined coal can be removed. A feed stream to the process consists of 73% coal, 11% ash, 11% sulfur, and 5.0% water (to suppress dust). The clean coal side of the process consists of 88% coal, 6.0% sulfur, 3.0% ash, and 3.0% water. The refuse side consists of 32% sulfur, with the remainder being ash, coal, and water. If 80 metric tons per hour of clean coal is required, determine the feed rate required for the mined coal and the composition of the refuse material. Also determine the mass rate for the refuse stream (in metric tons per hour).

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Fluids at rest possess no flow energy. a)- true b)- false

The higher the astm grain-size number, the coarser the grain is. a)-true b)-false