Wednesday, August 22, 2012

Depressuring Unit in PRO/II


The Depressuring Unit simulates the time-pressure-temperature relationships which occur when a vessel is depressured through a relief or control valve. The initial phase of the vessel contents may be either a vapor or a vapor-liquid mixture. Several different valve flow models and vessel configurations are available. Several heat input models are also available to simulate the pressuring of the vessel by a fire or other means. An optional external makeup stream may also be specified.
  1. Place a Depressuring Unit from Batch Tab and connect it with a feed and vapor stream
  2. Enter the Initial and Final Depressuring conditions which can be either based on time or pressure
  3. Enter the Calculation options which could be as shown in the figure or can even be left as default values
  4. Enter the Valve data. In this example, the Valve model is based on Supersonic Flow. Please refer to Help for further information about Valve constant – C
  5. Provide the vessel data. There are four options and the final one being Unspecified shape where the user can just enter the Vessel volume
  6. Enter the Heat input data, the various Heat Flow Models are shown in the figure
  7. Run and review results, user can also generate a plot from Output menu as shown