Process Analysis Problem 2: [40 MARKS] You are a process engineer working on setting up a medicinal plant company. One of the key steps is to dry wet solids in a continuous manner. As part of the design process, your company has approached two vendors to propose a dryer design. You have given them both the following specifications: Ambient air is at 20 "Cand 20% RH The maximum temperature of the air entering the unit should be less than 50 C As the solid travels through the dryer, water is evaporated at the rate of 100 kg/s. The dryer should be adiabatic Two vendors have proposed their designs. Each claim that its design is superior in terms of energy consumption. Upon inspection, you have narrowed down the key differentiators and prepared a simplified block flow diagram as shown in the attached sheet. Design 1 is a once-through dryer. Ambient air is heated up to 50 C and sent to the dryer. The moist air that has picked up the water from the solids leaves the dryer with an RH of 90%. Design2 is a dryer with partial recirculation. In this design, a portion of the outlet air is recirculated; mixed with the ambient air; heated to 50 C and introduced into the dryer. In the proposed design, the ratio of dry airflow in stream 4 to the dry airflow in stream 3 is 0.5. In other words, 50% of stream 3 is recirculated. The outlet air (stream 3) emerges at 90% RH Your role is to perform the following: 1. For Design 1, show the path taken by air as it travels through the dryer. Indicate the states and paths on the psychrometric chart titled Design 1. [5 MARKS] 2. By showing appropriate balances, complete the stream table. [5 MARKS] 3. What is the heat duty (in kW) of the heater in Design 1? (5 MARKS] 4. Design 2 is not straightforward to analyze, but there is enough information to solve it. Explain how you will approach this design and estimate all the associated states (1 to 4). if needed, describe your solution using the psychrometric chart titled Design 2 [10 MARKS] 5. By showing appropriate balances, complete the stream table. (5 MARKS] 6. What is the heat duty (in kW) of the heater in Design 2? (5 MARKS] 7. Which design will you recommend and why? (5 MARKS] Recirculated Air Ambient Heater Air out 3 90% RH Ambient Heater Air out 90% RH Design: Once-through Adiabatic Dryer Design 2 Adiabatic Dryer with partial air recirculation Dried Solid Wet solid Dried Solid Wet solid Once-through Adiabatic Dryer Adiabatic Drier with air recirculation 1 2 3 3 1 2 2 3 3 4 Dry air flow [kg/s1 Temperature (C) 20 so 20 50 Relative humidity [%] 20 90 20 90 90 Moisture content [kg W/kg DA] Enthalpy (kl/kg) PSYCHROMETRIC CHART FOR DESIGN 1 120 125 130 135 140 145 590.03 003 0.031 0.0.0 0.02 0.02 Hoon 10.00 S $ $ Estate At Saturation, Dry Ale 56 0.033 SELL 0.014 STT 0.023 0.022 0.021 0.020 0.011 0.010 0.017 0.010 0.018 0.014 0.013 0.012 0.011 2010 0.001 0.000 0.00 0.000 0.00 0.004 0.003 . 0.001 -0.00 Wet Bulbor Sata Temperature 0 15 20 25 0.75 0.00 Dry Bulb Temperature. C 0.45 Below O C Properties and Enthalpy Deviation Lines Are Force OC Humid Volume, m'hg Dry Air ATTACH THIS PAGE WITH YOUR SOLUTIONS PSYCHROMETRIC CHART FOR DESIGN 2 120 123 130 135 140 145 19.033 0.032 0.031 HA 0.030 0.020 0.028 0.027 0.026 $ 0.005 70 $ : Enthly At Saturation, Dry Air $ 1104 0.024 0.023 0.022 0.021 0.020 0.018 0.018 0.017 0.018 N9 0.015 0.014 0.013 NE 0.012 N0.011 0.010 0.000 0.000 0.000 0.000 0.005 0.004 F0.000 0.002 Wet Butb or Station Team