# plc used for titanium dioxide plant control

A

#### a a samson

has anyone used modicon quantum or any other plc for control of a titanium dioxide plant before ?
all the references i could find are with DCS only.
what is the reason for this - can't a powerful PLC be used ? are there any specific requirements which cannot be met ?
any help will be appreciated

D

#### David J

We are using Quantum PLC's to control a Titanium Dioxide process.

We are also controlling an acid regeneration process with this type of controller.

I have found nothing in the process that I cannot do with these controllers. We have discrete and continous control. All the controllers are networked using the NOE modules.

We have had great success with this product.

We use Concept programming package to program all our controllers and Monitor Pro as the HMI.

We have cascaded control, split range control, cascaded setpoints as well as the conventional PID control. We use Function block, Ladder Diagram, Sequential Function Chart and a small amount of Structured Text in these programs.

I hope this helps
David

A

#### a a samson

hi david,
any comments on your previous experience would help me understand why there are so few references of plc in this area. most of the specs are with DCS.
how many controllers did you use ? typically how many i/o's are there ?
look forward to hearing from you.
my email ID is [email protected]
regards,
abraham samson

B

#### Bob Peterson

IMHO - In general:

- A combination of a PLC and SCADA system can do anything a DCS can do, but the reverse is not always true
- Solving a specific problem with PLCs and a SCADA package is far less costly then with a DCS (don't believe the "total cost" lies)
- DCS's typically have pre-built easy to use templates for the more common and simpler things you typically have to do
- DCS's are really a pain to configure to do things they do not have templates for
- DCS salesmen are very good at spreading FUD regarding using PLC's for plant control
- DCS salesmen are very good at spreading FUD regarding using outside integrators to configure your DCS once you have selected a DCS
- The selection of a DCS for a plant is usually made by the wrong people for the wrong reasons but it really does not matter much since they all have roughly the same capabilities (much like PLCs do)
- There is little advantage to a so called "common tag database" since so little of the information is reused anyway
- I am not convinced that a giant DCS system despite it builtin redundancys is more reliable then hot backup PLCs
- It is much easier to find a competent integrator for a PLC based system than any DCS
- DCS's are pretty good at batch control compared to typical PLC/SCADA solutions
- You may find regulatory (government) compliance easier with a DCS although
I think the tide is turning on this one
- DCS's are not real good sequential control

Look around and you will see that a LOT of plants have turned away from the old DCS model and are embracing the PLC/SCADA model. The main reason is .

Bob Peterson

A

#### A A samson

my email ID is [email protected]
I would like further details on titanium dioxide plant control
thanks
A A samson

D

#### Donald Pittendrigh

Hi All

I think the smelter in my town uses Modicon for their plant, search for RBM in Richards Bay in South Africa, or Richards Bay Minerals. You should
be able to contact their engineering department, if not get back to me.

Bye
Donald Pittendrigh

R

#### Ronald Nijssen

Just some comments, this doesn't imply the other arguments are always true

Bob Peterson wrote:

>- A combination of a PLC and SCADA system can do anything a DCS can do, but the reverse is not always true

I agree, but if you provide all the built-in functions is it still something that makes sense

>- Solving a specific problem with PLCs and a SCADA package is far less costly then with a DCS (don't believe the "total cost" lies)

This is only true if you do not provide all functions a DCS provides (diagnostics, standards, continuity). Building the rich front-end Operator
Dialogs, Faceplates, Diagnostics from scratch will cost much more than an out-of-the-box solution

>- It is much easier to find a competent integrator for a PLC based system than any DCS

How do you qualify a competent SI? Will he develop and honor (undocumented) PLC logic standards that have been used in the existing applications? How will you not get different standards if you need to automate multiple processes? And who will support these different solutions in the long run, what about upgrades of HMI and/or PLC, will the application upgrade as easy?

>- DCS's are pretty good at batch control compared to typical PLC/SCADA solutions

>- You may find regulatory (government) compliance easier with a DCS although I think the tide is turning on this one

Let's validate each Motor block of each Integrator active on a Pharmaceutical site, or use the one from the DCS vendor without any effort; the only alternative is to validate and own the standard as end-user...

Kind Regards
Ronald

D

#### David J

> how many controllers did you use ? <

We have approx 6 controllers in this process.

> typically how many i/o's are there ? <

There are about 700 I/O on each unit consisting of discrete and analog.