FREQUENTLY ASKED QUESTIONS
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Q. What are system
Minimum requirements are:
1 System is pre-set for PI, IP21, PHD or Exaquantum. If yours is another version please contact
EP Monitoring .
- An IBM compatible PC with an Intel Pentium 800 MHz processor or equivalent.
- 128 MB RAM
- Windows 98/2000/XP/Vista, Microsoft Excel 97 or later.
- A data historian1 accessible to Microsoft Excel, capable of producing current values for up to 166 process variables, 21 process variables back 20 minutes in history and 21 process variables back 40 minutes.
- Instrumentation for feed, reflux (if applicable), heating medium, operating pressure (if applicable) and Delta pressure/temp. (if applicable) for each tower.
- Instrumentation for all analyzers (if not using lab data) and/or temperature needed to monitor overhead and base composition of each tower.
Q. Will this system work with my particular data historian/data access software?
A. Our systems have been installed in operations using OSI PI, AspenTech InfoPlus.21, Honeywell PHD and Yokogawa Exaquantum. Any software that will provide an interface between the users DCS and Microsoft® Excel can be used.
Q. What if I don’t have a data historian or data access software?
A. Our systems have been installed in operations with no data historian or data access software whatsoever. The only requirement is that the user have the ability to transfer process data from the DCS into text files that can be imported into Excel. Under some conditions an installation fee may apply. Some features may be limited.
Q. Will the System work with Excel 5.0 or Excel 95?
A. If using Excel 5.0 or 95 the system will still provide instructions for optimization but many important features such as formatting of information in the “Troubleshooting”, “Instructions” and “Introduction” worksheets may be lost.
Q. Will this system work if I don’t have a way for Excel to access my operating variables?
unless you want operations to input the process data manually.
Q. Will this system work correctly if I don’t have on-stream analyzers on my columns?
A. Yes. The system has been successfully set up to use temperature, column Delta temperature, or lab data if there is no on-stream analyzer on a particular stream. If lab data is used the system will not be able to determine direction of movement however. It may take a little longer to optimize a column using lab data due to the length of time between samples.
The system has also been customized to calculate compositions in
Q. What if I don’t have instrumentation to measure column DP (Delta pressure)?
A. Overhead and base pressure indications (if available) may be used to calculate DP. Another alternative might be to use column DT to infer DP. This may not always be the best choice, however, as DT is more a function of composition differences between the OH and base, while DP is directly a function of loading (composite vapor and liquid), as well as column internals.
Q. What if I don’t want to change operating pressure regardless of feed rates?
A. No problem. This feature can be disabled easily without affecting other decisions.
Q. What if I don’t want to use the forecasting feature when making decisions?
A. No problem. This feature can be disabled. It is disabled automatically if using lab data on a particular variable (in lieu of on-stream analyzers or temperatures).
Q. How does this system work if a column has no external reflux?
A. This system has been used very successfully on columns having no external reflux.
For instance, this system has been used on a benzene drying column utilizing column delta temperature as the key control variable for the overhead. Please contact
EP Monitoring to discuss your particular application.
Q. Will this work on columns with side draw trays or intermediate condensers?
A. Generally speaking, if process engineering can provide the critical operating parameters and the operating variables affecting these parameters, the system can be adapted to these types of columns. Composition of side draw material or DT (Delta temperature) above and below side draw tray might be used in some cases. Each of these will be handled on a case-by-case basis.
Q. Will this work on
multiple side draw columns?
system was designed primarily for binary distillation or columns
with only one side draw. However, recent innovations have made the
software much more adaptable to multiple side draw towers. To
accomplish this, each set of 2 side draws (i.e., on a crude
tower, naphtha/kerosene, kerosene/diesel, diesel/HAGO, etc.)
is operated as one “tower” with logic and built-in overrides to
control each set, while monitoring the others. There is also some
customizing involved to provide instructions for the operator to
adjust pumparounds. Please
contact EP Monitoring for more information.
Q. Will this work on columns with unusual specs (such as color)?
A. Yes provided this “color” can be measured, imported into Excel and the operating variables affecting color can be properly identified.
Q. Can this system handle complicated processes (where several columns work together)?
A. This system has been successfully installed using the composition of a second column's distillate or other input to adjust the loading on a column immediately prior. These systems need to be handled on a case-by-case basis.
There is also an external override system that can be set up
very easily to monitor other towers and conditions in your process
before making changes to reflux, reboil or pressure. Please contact
EP Monitoring to discuss your particular application.
Q. What if my process changes often (batch unit) and the components monitored as well as other operating parameters need to change with each run?
A. No problem. The system can be set up to work with multiple runs for a given distillation column. After setup the operator or engineer need only enter the name of the run and the system will change the operating parameters (even components monitored) to fit the particular run.
However, this requires extensive customization of our standard product. Please contact
EP Monitoring to discuss your particular application and for an estimate of one-time special fees for customizing our product for your unique situation.
Q. My process does not reach what would be considered steady-state very often. How about this?
A. Current distillate and base compositions and/or temperatures are compared to conditions 20 and 40 minutes prior. The system will provide a message and make no recommendations unless variations are within established limits. The setting for this feature is normally 20% for compositions and 1% for temperatures but can be adjusted to fit the individual process.
Q. Can this work with Closed Loop Control Systems?
A. Generally speaking, if process engineering can provide the critical operating parameters and the operating variables affecting these parameters, the system can be adapted to these types of columns. Special customizing may be required if the CLCS resets the controller for any of the operating parameters being monitored by our system.
Q. Does this work on columns with stripping steam?
A. If process engineering can provide the critical operating parameters and variables affecting these parameters, the system can be adapted to these types of columns. On columns with stripping steam, a reliable method of determining base composition would need to be in place since temperatures may not be indicative of composition.