Rod Dry Dec 2013

Training Module #6: Problem Statement Low pressure steam (1 barg) is condensed in a heat exchanger with cooling water. The exchanger has 58 tubes (DN25 Sch 40) 10 m long. Cooling water is supplied at 40 °C from a pump via a control valve. (Quick Start default settings will be used for the heat exchanger, pump and valve.) 1.Under normal operating conditions, what is the maximum cooling water temperature and by how much do the heat exchanger tubes expand (when going from ambient to operating temperature)? 2.If a fouling layer equivalent to 1 mm of cement is present on the cooling water side of the tubes, what is the expected reduction in steam condenser capacity? 3.Is it possible counteract this capacity reduction by increasing cooling water flow? Heat Exchanger Fouling

Training Module #6: Step 1 of 9 1.Click on the Quick Start Icon ( ) and say “Yes” to the current project overwrite warning. 2.Select “Water Tank with Pump and Steam Condenser”, then press “Go”. Base Case: Cooling Water Rate 161 t/h Condenser Capacity 9.7 MW

Training Module #6: Step 2 of 9 1.Click on the Result Graph Icon ( ). 2.Check the top variable and select Fluid Pressure 3.Check the second variable and select Fluid Temperature 4.Select “Maximum” Base Case Maximum Water Temp is 92 °C

Training Module #6: Step 3 of 9 1.Right-click on the right-hand half of the tube bundle and select “Properties” 2.Toggle “Process Temp” on and off Tubes are m long at ambient temp and m at operating temp linear tube expansion is 9 mm

Training Module #6: Step 4 of 9 1.Right-click on the heat exchanger tubes (on the right-hand half of the bundle) and select “Edit” (the left-hand half is for editing the purple steam cylinder, which is not what we want at the moment). 2.Click on the small grey bar (just below the material type drop-down box) to activate the lining/cladding editor.

Training Module #6: Step 5 of 9 1.Select “Single-Layer Internal Lining”. 2.Set the layer thickness to 1 mm and the lining material type to “Cement”. 3.Click OK

Training Module #6: Step 6 of 9 To “see” the cement lining, toggle “Show/Hide Pipes” ( ) on and off. You can now see the cement fouling layer “pipes” inside the purple steam tube. If you wish, you can also toggle “Show/Hide Structural Items” ( ) on and off to see the cement “pipes” without the purple steam cylinder.

Training Module #6: Step 7 of 9 1. Solve the model by pressing “Solve” ( ) 2. Examine the result… Fouled Case: Cooling Water Rate 157 t/h Condenser Capacity 3.3 MW

Training Module #6: Step 8 of 9 1.Open the water flow control valve to 100%. This time, try hovering on the valve and scrolling the mouse wheel to open it (rather than right- clicking and selecting “Edit” as you did earlier). You can, of course, use the “Edit” option if you prefer. 2.Re-solve the model. Fouled Case with Fully Open Valve: Cooling Water Rate 272 t/h Condenser Capacity 3.65 MW

Training Module #6: Step 9 of 9 Press the result Graph Icon ( ) Pressure his higher, water temperature is lower compared to the base case

Training Module #6: Solution Review Low pressure steam (1 barg) is condensed in a heat exchanger with cooling water. The exchanger has 58 tubes (DN25 Sch 40) 10 m long. Cooling water is supplied at 40 °C from a pump via a control valve (Quick Start default settings will be used for both pump and valve). 1.Under normal operating conditions, what is the maximum cooling water temperature and by how much do the heat exchanger tubes expand (going from ambient to operating temperature)? Answer: cooling water maximum is 92 °C and the tubes grow by 9 mm. 2.If a fouling layer equivalent to 1 mm of cement is present on the cooling water side of the tubes, what is the expected reduction in steam condenser capacity? Answer: 9.7 MW drops to 3.3 MW 3.Is it possible counteract this capacity reduction by increasing cooling water flow? Answer: Not really – increasing flow from 157 t/h to 272 t/h only increases condenser capacity from 3.3 to 3.65 MW. Heat Exchanger Fouling

Final Step: Save For Future Reference 1.Select File  Save ΣPipe Project As… and call this case “Steam Condenser Example”, then press “Save”. Well done, you are ready for module #7!