Difference between revisions of "PH Loop"

From Chemical Engineering @ UP wiki
Jump to: navigation, search
(Adding starting pages for the rigs with rig photos (2 of 6))
(Long overdue wiki update)
Line 25: Line 25:
  
 
== Rig maintenance ==
 
== Rig maintenance ==
=== Pre 2009 ===
+
The maintenance of the pH rig is documented [[PH Rig Maintenance|here]].
Maintenance and changes made to the pH rig before 2009 are not explicitly maintained on the wiki. Consult the project documentation of previous years for said changes.
+
=== 2009 ===
+
'''Wiring/Instrumentation'''<br/>
+
Wiring of rig found to be in a state of disrepair. An attempt is made to fix all wiring and restore all electronic equipment to a working condition. Fixed equipment/wiring is listed below:
+
* I/P transducer for control valve 2 - re-fitted transducer, reconnected piping and wiring.
+
* Control valve 2 - reconnected piping.
+
* All the RTDs have been removed from the rig (scavenged?) - in process of replacing them.
+
* Control valve 1 seems to be stuck. Apparently the original valve was removed and replaced by current non-working valve. In process of testing valve.
+
 
+
'''Piping'''<br/>
+
Numerous leaks were fixed and connections made where piping has been scavenged off the rig.
+
 
+
'''Structural'''
+
* Stands for feed tanks (currently dustbins) were found to not give sufficient support when tanks are full. Constructed new feed tank stand.
+
* Fitting of stirrers to tanks found to be flimsy - refitting them to more sturdy structures.
+
* Rerouted pipe connecting CV001 and FE001 - cut away some of the metal structure to remove strain from pipe.
+

Revision as of 19:04, 10 November 2009

The pH control rig

PH control is a difficult problem due to the highly non-linear nature of the system. The steep slope of the titration curve around the pH = 7 point amplifies pH variations for even small base/acid addition variations. The pH control rig in the PMC lab illustrates that pH control is by no means impossible (albeit on a laboratory scale).

Current/Previous projects

1999

F.J. Botha, Ondersoek van die Dinamiese Gedrag van Sisteme waar pH Gemeet en Beheer word {Investigation of the Dynamic Behaviour of Systems where pH is Measured and Controlled}
[Hard copy of report available in pH rig folder]

2003

T. Leeuw & G. Mascini, pH Rig 2003 - CPL780 Process Control Laboratory
Report | Project files

2005

A.J. Swanepoel & M. Swanepoel (Botha), Model Based Control Laboratory, pH Control
Report | Project files

2007

C. Steyn, Fuzzy Logic Rule-Based Controller Design, Neutralization of Strong Acid with Strong Base
Report | Project files

2009 (Current)

A.H. Campher, project to determine methods of obtaining the attainable- and desired output spaces (AOS and DOS) from a process model.
[Report] | [Project files]

Documentation

Large scale renaming of instruments, valves and tanks are being done. This renders all previous rig diagrams obsolete. Only 2009-updated diagrams should henceforth be used.

Process Flow diagrams

Piping & Instrumentation diagrams

Wiring diagrams

Rig maintenance

The maintenance of the pH rig is documented here.