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Example 3 - Liquid Dryer

 

Problem 1

 

Material is know as follows

 

Type: liquid solution

Feed mass concentration = 0.58 kg/kg.

Feed temperature = 85 oC.

Feed pressure = 102 kPa.

Product moisture content = 0.05 kg/kg wet basis.

Product temperature = 65 oC

Specific heat of the absolute dry material = 1.26 kJ/kg.oC.

Mass flow rate wet basis = 5000 kg/hr

 

Drying air has the following conditions:

 

Pressure at dryer inlet = 103.2 kPa

Temperature at dryer inlet = 120 oC

Absolute Humidity at dryer inlet = 0.009 kg/kg dry air

Temperature at dryer outlet = 55 oC

Pressure drop of air in dryer = 1.2 kPa

 

Calculate how much drying air is needed as well as what is the outlet humidity of the drying air.

 

Solution Steps:

 

1.      Save and close current flowsheet if you currently work on a flowsheet. Otherwise start ProcesSimO and close the new empty flowsheet.

2.      Go to Materials | New Flowsheet Settings to bring up the New Flowsheet Settings dialog. Select “Generic Drying Material” in the Select Drying Material list box. Then click “Set” button to set this material as the drying material of the new system to be created. Close this dialog. You can neglect this step if you come from Example 2.

3.      Create a new flowsheet by clicking the first icon  in the toolbar or clicking File | New.

4.      Create a liquid dryer on the flowsheet and double click the icon of the dryer to bring up the dryer’s editor.

5.      Input in “Mat 1” column 5000 kg/hr in the Mass Flow Rate (wet basis) field, 85oC in the Dry-bulb Temperature field and 0.58 in the Mass Concentration field.

6.      Input in “Mat 2” column 55oC in the Dry-bulb Temperature field and 0.05 in the Moisture Content (wet basis) field.

7.      Input in “Gas 1” column 103.2 kPa in the Pressure field, 120 oC in the Dry-bulb Temperature field and 0.009 kg/kg in the Absolute Humidity field.

8.      Input in “Gas 2” column 55 oC in the Dry-bulb Temperature field.

9.      Input in “Gas Pressure Drop” field of the Dryer group box 1.2 kPa.

10.  After the enter key of last input is hit, the dryer is solved and all the calculated variable values are displayed as shown in Figure 3.

 

 

Figure 3