Tutorials /Deaeration /Two Heat Exchangers

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Model Development

Simulation Diagram

Figure 2 illustrate the HYSYS simulation diagram of the heat exchange process.

Figure 2: HYSYS representation of the heat exchange process.

Model Description

 The heat exchange process consist of two heat exchanger named Ex-1 and Ex-2. The hot streams flow throught the shell of both exchangers and the cold streams flow through the tube.  The name of the hot stream entering Ex-1 is hot in and its exit stream is hot inter. The stream hot inter is then fed into Ex-2 and its exist stream is called hot out. The cold stream named cold in enters Ex-2 where it is heated and its outlet stream is called cold inter. The stream cold inter is then fed into Ex-1 and it is further heated and its outlet stream is called cold out.

Selecting Fluid Package and Components

1. Open a new case in HYSYS.
2. Select PRSV for the fluid package.
3. Select H₂O for the component.

Setting up the PFD

1. Enter the Simulation Environment.
2. Select from the object palette the heat exchanger icon and install it on the PFD.
3. Double click on the installed exchangers and name it Ex-1.
4. Enter the stream names as shown in figure 3.

Figure 3: Stream names of Ex-1

5. Install a second heat exchanger on the PFD and name it Ex-2.
6. Name the streams of Ex-2 as shown in Figure 4.

   

   Figure 4: Stream names of Ex-2

Unit Operation Specification

1. Open window for Ex-1.
2. Click on Parameters on the Design tab. On the parameters page, on will see Delta P of the tube and shell. Delta P stand for pressure drop.
3. For the tube side, enter a Delta P of  25 psi.
4. For the shell side, enter a Delta P of  150 psi.
5. Enter the same numbers for the pressure drop in exchanger Ex-2.

Specifying the Streams

Stream hot in

1. To open the hot in stream, on the PFD, double click on the stream hot in.
2. Enter the pressure and temperature given in the problem statement for the hot feed stream. These are 1200 psig and 300 °F, respectively.
3. Go to the Composition page.
4. Since the stream is 100% water, in the cell next to H2O, enter 1 for the mole fraction.

Stream hot inter

1. Open the hot inter window.
2. Input the temperature of this stream as 265 °F.

Stream hot out

1. Open the hot out window.
2. Input the temperature of this stream as 200 °F.

Stream cold in

1. Open the stream cold in window.
2. Enter the pressure, temperature, and mass flow rate given in the problem statement. These are 130 psig, 125 °F and 200 lb/hr, respectively.
3. Set the composition of the stream cold in to 100 % water.

Stream cold inter

1. Open the cold inter window.
2. Input the temperature of this stream as 180 °F

Viewing Results

After all the streams are specified, the simulation should solve. To view the results of the simulation, one can either open each stream window or one can view the workbook. To view the workbook, click on the workbook icon located on the menu bar.