I with my team am working on I & C upgradation of ammonia plant. We have two options at our hands, either to go for in vogue DCS, an easier option to adopt, or implement the Fieldbus, a novel concept. The problem lies in convincing the managment which is more inclined to DCS because it is in use in contemperory industries.
I know all the basic advantages of FF over DCS like Costing, Less time of installation, Intrinsically safe, Device description etc but these are proving no good for us.

I think we are missing the punch line. I would ask all those who have any experience in implementing the FF at any site in general and at Ammonia plant in particular, to share their valuable experience with us, to help me pull out of this fuss.

 

Well, first of all, please pardon me, but implementing FF or DCS isn't an either/or issue. FF is simply a communications protocol...unless you are going to attempt the fabled "control on the wire" portions of FF that everybody, or nearly everybody said they wanted but never tried to implement.

Find yourself the DCS that pleases...and use FF as the field device communications.

Walt Boyes
Editor in Chief
Control magazine
www.controlglobal.com
blog:Sound OFF!! http://www.controlglobal.com/soundoff
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[email protected]

 

First, You accept the proposal of Management
of implementing DCS.

Would you be kind enough to let us know the
existing set up of instruments

Regards
jari
[email protected]

 

I appreciate your response to my query. The existing instrumentation is all pneumatic,most of which have been working since plants' errection in 1979, means, it requires a major paradigm shift to bring I & C of our plant into new world.

 

First, fieldbus is hardly "novel", it has been around for 12 years or so.

FF has come along way over the past ten years. The specifications have been clarified, corrected, and complemented. Product implementations of the technology have been corrected and completed. Better tools have come to market. Procedures for project execution and practices for operations and maintenance have been established. It is far easier to be successful now than only a few years ago. Most major EPCs now have FF experience. Your management should not worry about "immaturity".

You may wish to justify to your management on the following basis:
* Project savings
* Operations improvement

Here is a summary of why FF works so well for plants:

Project Savings
- Less wires, conduits, trays, terminations
. Multiple devices per bus
. Multiple signals per device
- MOV, MV, feedback etc.
- Reduced control room footprint
. Fewer I/O cards and barriers
- Fewer engineering drawings
. Multiple loops per drawing
- Faster loop check and commissioning
. Automatic 'ring-out'
- Enables innovation...
. New classes of digital devices

Operation & Maintenance Improvement
- Better accuracy
. No precision lost in D/A & A/D
- High signal integrity
. Distortions can be detected
- More powerful diagnostics
. More current for devices
- Engineering unit
. Measure to sensor limits
. No range mismatch
- Stave off obsolescence
. Firmware download
- Easier device troubleshooting
. Remote Diagnostics
- Validity display and loop shut-down
. Signal status
- Predictive maintenance
. Diagnostics Alerts
- Easier replacement and servicing
. Fewer Connections

Contact me directly at jonas.berge (at) emerson.com

For an FF project to be a success it has to be planned, engineered, and designed correctly. If you follow old DCS practices for design, loop check, commissioning etc. all you will get is a more expensive DCS without new fieldbus benefits. However, if done correctly FF will deliver on the great promise of digital control and architecture. These practices have been
worked out and fine tuned by leading automation vendors over thousands of projects the past ten years.

Cheers,
Jonas

 

Dear Rana,
I think You want to ask that should you may adopt simple Hardwired Instrument System or Communication based Instrument System.

Feild Bus or some of the other type of Communication based I&C system are initially costly to implement but soon they pay off in terms of reliability and time saving during maintenance.

So if you have budget you must go for Field Bus based I&C system

If you want to further discuss this issue, you may call or e-mail me at

[email protected]
00-92-3002503022

 

FF is not always more costly to implement, we have seen big time savings when it comes to comissioning of loops.