Depressuring Unit Main Window

This window is used to supply the input data for a depressuring unit.

Initial Depressuring Conditions

The initial depressuring conditions can be based on either a specified starting time or a specified starting pressure. The default is to start the depressuring calculations at the beginning of the simulation (time zero.) You may enter a different time to begin the depressuring calculations.

Note: This is only available with the "Fire Relief Type" models, therefore it is not available for the Isothermal, Semirigorous Blowdown, and Rigorous Blowdown models.

Final Depressuring Conditions

To set the final depressuring conditions, you may specify values for the final vessel pressure and/or the elapsed time. You can choose to measure the elapsed time from time zero or from the start of relief by clicking on the highlighted text. If both the final vessel pressure and the elapsed time are selected, the depressuring calculations will stop when the first criteria is satisfied.

Selection of Thermodynamic Method Set

For problems where more than one thermodynamic method has been specified, you can select which thermodynamic method set is to be used for the Depressuring Unit from the list.

Calculation Options Button

User-supplied values for the relative volume tolerance per time step, the maximum number of time steps, and the time step size can be entered on the Depressuring Calculation Options Window.

Valve Data Button

The valve model used to define the flow characteristics of the relief valve or control valve must be specified. Valve data can be entered on the Depressuring Valve Data Window.

Vessel Data Button

The Depressuring Vessel Data Window is used to enter the geometry and/or volume of the depressuring vessel. The vessel configuration must be given.

Heat Input Button

A heat input model must be selected on the Depressuring Heat Input Window. If there is no heat input to the depressuring unit, it is not necessary to change the default selections supplied in this window, as the default supplies no heat input.

Print Options Button

By default, component compositions are printed at all calculation step times. Intermediate printout is printed at each calculation step time by default. The Depressuring Print Options Window allows you to change these defaults and to control the intermediate and final printed results for the depressuring unit.

Makeup Stream Button

The Depressuring Makeup Stream Window allows you to select one feed stream which will be used as a constant-rate makeup stream.

Products Button

The Products button becomes available when the product streams are added to the depressuring unit. When you click the Products button, the Depressuring Products Window appears. In the Depressuring Products Window, tag the time steps to the product streams.

Complete technical details may be found in topics under Depressuring in the PRO/II Reference Manual.

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