REVERTEX CHEMICALS - Kettle 1 and Kettle 5 upgrade
Automation of two Kettles to the S88 batch standards. We were required to write our own Phase Logic Interface layer to allow the IBatch package to operate with the PLC according to the S88 standard This meant that normal PLC sequencing was not allowed and the system had to be totally flexible and modular. According to the S88 standard phases are programmed to perform a specific task e.g Autocharging. The Autohcarging phase would have to consist of starting logic, running logic, holding logic, restarting logic, stopping logic and aborting logic. In the running logic, when the step index has reached a certain numerical value the normal code e.g open a valve or control a temperature via a PID block etc would reside. Once the amount to be charged or the required temperature has been reached then the phase will change the step index to allow for reporting and closing of valves and then set a running complete flag. The batch package would recognize the flag and then allow the next task to begin.
At any stage during the running logic, the Batch package could inform the PLC to either abort, hold or stop the phase that is running. The phase would then set the aborted, held or stopped flag and obviously close valves or whatever the specification called for. Everything in the plc program is treated as a container or object and can therefore be managed easily and used at any time, by either operating sequentially or in parallel. Strict handshaking allows for strict control, for example if communication is lost between the Batch and the PLC then the PLC puts all phases into a holding state.
The Ibatch and Moeller PLC had never been used together before, therefore all the development had to be done “in house”. This was a world first, with communication watchdog timers and watchdog tags a communication requirement. We are extremely proud of our achievements. We made full use of PID, Interpolation, PID cascade controller, Cycle counter, and Arrays to allow the software to perform the required tasks. Control of the large hydraulic mixer speed as well as feed pump speeds using Moeller drives. The reaction is exothermic and therefore great care has to be taken with the Cascade loops and safety mechanisms built into the software. All equipment has been designed for use in hazardous areas and SABS loop approvals have been provided.
With the new stricter laws on effluent and stormwater monitoring Pro-Temp was
approached to to install a reliable effluent control system which could be monitored on the existing Scada in the control room. PH and level controllers are used to control the pumps and to log all the information Via a Moeller PLC and display the information on Fix dynamics Scada.
Ammonia safety shutdown system
An Ammonia safety shutdown and control system had to be developed to allow multiple users to use the Ammonia line. Only one user could use the line at a time, to avoid a vacuum being drawn between two different vessels. An emergency stop would shut down all the Ammonia valves in the case of an Ammonia leak.
REVERTEX CHEMICALS - Kettle 7 Upgrade.
Project upgrade of new kettle. RSBatch and Moeller X Controller with embedded Windows NT and OPC server communication. Programming via Ethernet. Adroit Scada and RSBatch browse tags via OPC client. Hazardous area, exothermic reaction. Various I/O, pneumatics, weighing Pid cascade control, reporting and logging. New PLI developed, phase logic and control modules.