Calibration Environment

V4 builds on the Distop calibration application introduced in Petro-SIM V3, expanding it to work against a wider range of objects. We have made calibration more tightly integrated by having it operate as an environment that you enter and leave through the PFD. You calibrate groups of objects together: typically a fractionation system like crude and vacuum distillation or a reactor and its main fractionator.

The basic principles of calibration are the same regardless of the objects being calibrated. Separation objects are calibrated against their feed created by assay synthesis of its products. Reactor objects are calibrated against their feed and their whole effluent, created by assay synthesis of the downstream fractionator products. For example:

  • A Crude Distillation Unit would have its feed synthesized from data on its products.
  • An FCC and Main Fractionator unit would have the FCC feed streams synthesized from their own data and have the reactor effluent synthesized against the fractionator product data. The FCC reactor then calibrates itself against this synthesized feed and effluent. The Main Fractionator usually calibrates itself against predicted reactor effluent but can also be configured to calibrate against its synthesized feed.
  • Recycle streams to reactors are always torn and set to their measured values.

Reactors always calibrate against either whole effluent composition and property distributions or against perfect cuts of those distributions. Reactor calibration is separate from the fractionator calibration, with the reactor not having access to the fractionator product measurements.

V4 provides an Auto Setup mechanism that takes care of most configurations, determining from its rules and your selected scope what needs to be synthesized from what. You can override any of these auto-determined settings using a variety of point and click techniques. The Calibration panel sits within the PFD view as you see below:

Calibration Data

Calibration works using measurement data held in meters; predictions work using data in streams and unit operations. The Calibration Environment takes care of ensuring the stream, synthesis processes and reactor/fractionator unit operations get to see the meter data they need. The Calibration Environment also takes care of ensuring the streams and unit operations being calibrated get back to their starting state on exit from calibration apart from having new calibration factors.

Getting started

You enter the calibration environment by selecting a group of objects and sending them to calibration from the PFD Object Inspect menu or from the Calibration button on the PFD toolbar. You will notice the PFD window shrinks in size and a calibration panel appears on the right hand side. You will also notice that objects in the PFD not being considered in the calibration are grayed-out.

We have built in an Auto-Setup method that will handle the common Column and Reactor flowschemes automatically. You can then adjust the configuration to suit your specific needs in situations where you want to synthesize a reactor effluent or column feed from a different set of downstream measurements or where it is unable to resolve complex recycle loops.

What can be calibrated

  • Column operations using the Distop solution algorithm
  • FCC, Reformer, Coker, Hydrocracker, Naphtha Hydrotreater, Diesel Hydrotreater, VGO Hydrotreater, Residue HDS, Visbreaker, VGO Cracker and Alky reactors
  • Component Splitters using the Distop solution algorithm or using split fractions or TBP Cut Points

Distop Calibration technique

We have expanded on the techniques in V3 to take advantage of Distop’s automatic calculation of section efficiency to meet observed volume interchange. Optimization is then used to calculate the best fit front and back shape factors.

As part of the above, we have added techniques that allow calibration to calculate intermediate stream cut points and volume interchanges. These make it easier to calibrate sequences of columns using only boundary stream flows – for example, calibrating a CDU and VDU where the Atmospheric Residue is not sampled but the VDU products are.

Recycle streams

You will need flow and composition/property measurements for recycle streams before calibration will start. Typical refinery arrangements will have column draws that split into the recycle and column product. You may have flows for each of these streams but will usually only sample one of the three. You can avoid having to enter meter data multiple times by linking meters.