Wet potassium dichromate crystals (90% crystals and 10% entrained solution) are fed to a dryer where they are contacted with dry hot air. The entrained solution is saturated at 30°C and contains 0.2 kg solute per kg of water. The air leaving the dryer has a dew point of j9.2 °c. Determine the flow rate of inlet air in L/h at STP conditions, for a production rate of 1000kg/h of dry dichromate crystals.

A fully charged battery contains 0.02 kmol Ag₂O (silver oxide) and 0.02 kmol Zn (zinc). The battery is initially at a temperature of 21°C. The fully charged battery is then discharged for half an hour under adiabatic conditions (no heat leaves the system). During the half hour of being discharged, the electric current from the battery does 200 kJ of work external to the battery system (none of this external work heats the battery). During this half hour, 0.001 kmol of both reactants are consumed in the net cell discharge reaction: Please see the following table for heat capacities and heats of formation. The heats of formation below show the amount of energy (kJ) needed to form one kmole of each component. If the heat of formation is negative, then forming that species releases energy (to do work or provide heat). Therefore, to create one kmole of silver oxide 29000 kJ energy is released and is generated in the battery (for work or heat), and if one kmole of silver oxide decomposes…

A counterflow tunnel dryer was used to dry the apple slices from an initial moisture content of 65% to 5% (wet basis). Hot air enters at 95°C with 1% RH, and exits at 52.0°C. If the temperature of the product throughout the dryer is 20 °C and the specific heat of the solid product is 2.2 kJ/(kg °C), determine the rate of hot air required to dry the wet product at a rate of 160 kg/hour. Determine the RH of the air exiting the dryer. a. Drying air rate (ma) = Answer kg/hour. b. Dryer exhaust air RH = Answer %

One way to make coal “cleaner” is to gasify the coal into “city gas”. In a proposed molten-iron coal gasification process pulverized coal of up to 3 mm size is blown into a molten iron bath and oxygen and steam are blown in from the bottom of the vessel. Materials such as lime for settling the slag, or steam for batch cooling and hydrogen generation can be injected at the same time. The sulfur in the coal reacts with lime to form calcium sulfide, which dissolves into the slag. The process operates at atmospheric pressure and 1400 to 1500°C. Under these conditions, coal volatiles escape immediately and are cracked. The carbon conversion rate is said to be above 98% and the gas is typically 65 to 70% CO, 25 to 35% hydrogen, and less than 2% carbon dioxide. Sulfur content of the gas is less than 20 ppm. Assume that the product gas is 68% Co, 30% H2, and 2% CO2. Calculate the enthalpy change that occurs on the cooling of 1000 m3 of the gas at 1475 °C and 1 atm to 25°C and 1 atm.