Exapilot is Effectively Applied to Polypropylene Plant and Optimizes Operation, Cost Savings

About Safripol

Safripol, Sasolburg,
South Africa

Safripol is a leading plastic manufacturer in South Africa. Safripol can produce 120,000mt/year of polypropylene (PP), utilizing LyondellBasell's Spheripol technology and also produces 160,000mt/year of high density polyethylene (HDPE). PP and HDPE are used for plastic components and products, from food wrapping to automotive parts.

System Overview

The polypropylene plant uses Yokogawa's CENTUM CS for more than 15 years without any major problems, including the following environments.

1. MODBUS communication between the DCS and other systems (Siemens, Yokogawa Analyzers, Moore Apacs, other companies like Sasol and Natref)
2. Exaplog is used for the alarm management system
3. Exapilot is used for grade change procedure
4. STARDOM is used for compressor control

Safripol started the migration process to CENTUM CS 3000 in 2007 and CENTUM VP will be installed by the end of this year.

The Challenges

Due to Global competition Safripol is striving for high efficient plant operation. Safripol is also improving the quality of the product by PDCA method for further sustainable manufacturing. The following issues were raised in the production department and the challenges were addressed.

1. Keep consistency of operations and product quality
2. Reduce transition material
3. Training for new employees
4. Reports for every batch operation as a product tracking data storage
5. Optimise, standardise and reduce procedures
6. Cost Saving
7. Empower the operational team in order to assess new ideas

The existing grade change procedure takes 2.5hours and the overview of the procedure is shown below. Safripol configured this procedure into Yokogawa's Exapilot.

The Benefits

Due to the natural differences between individuals, each operator will do the same job differently, although manual standard operating procedures are available. Although the operators did their best, issues were raised regarding the consistency of the operations during grade changes.

By using Yokogawa's Exapilot, Safripol were able to eliminate product variations and kept the operations consistent, thereby reducing operational costs drastically by eliminating " off spec" products during transitions.

Safripol also uses Exapilot in order to facilitate operator training regarding grade changes - The available modes allow the new employees to run a procedure without influencing the plant.

Exapilot also allows the assessment of procedures to ensure flawless execution.

An Exapilot report is available in order to give a step by step report of every action taken, in order to track the procedure from start to end.

Customer Satisfaction

Here are some comments from the operators:

• "It gives me more time to concentrate on other plant related issues, while the Exapilot takes care of the grade change."
• "It ensures consistency of grade changes"
• "It eliminates the inconsistency introduced by new operators"
• "It provides an opportunity to test run procedures/sequences to get a feel for the effects it may have on the process before making permanent changes to the logics"
• "Valuable operational knowledge is not lost due to natural migration of older employees"

And finally, the Process Information Engineer commented about Exapilot as follows.

• It's an electronic tool that combines the knowledge of the process Engineer and the Super operator into an interactive, electronic procedure which communicates with the DCS and does exactly what the procedure require, every time and without any deviations.
• It reads from the DCS, compare variables with specific values and if satisfied carries on and write values or actions to the DCS, without any required action from the operator, but if required conditions are not met, the procedure does not continue.
• It's main purpose is to take the complicated repetitive tasks out of the hands of the operator, in order for him to concentrate on the rest of the plant.
• This is your ultimate operator –highly skilled and does not show any complications associated with a normal working force.

Quality Measurements: Page 35

Final product Xylene Soluble content
measured by NMR – Before Exapilot

Difficult to coordinate two contradicting process settings during grade change (C2 increase vs Donor increase) Poor consistency

Final product Xylene Soluble content
measured by NMR – After Exapilot

Excellent coordination and repetitiveness facilitated by Exapilot