Evonik Degussa: A case study in explosion proof wireless networks
16 July 2008
As part of its continuous improvement initiative, Evonik Degussa Seal Sands recognised the need to measure and improve the Overall Equipment Effectiveness (OEE) of its critical equipment. Better monitoring of equipment was an essential part of the drive to enhance overall efficiency in the plant. Chris Steel, Continuous Improvement Manager at Evonik Degussa Seal Sands, explains how installing an explosion proof WLAN has enabled quick, efficient assessment of OEE to be extended to the extreme environments and Zone 1 hazardous areas found in its plant.
“OEE is the framework for measuring how effectively a process is producing product in the time it is planned to run, by breaking it down into three constituent components (availability, performance and quality), OEE helps measure and highlight areas with the greatest potential for improvement, and provides a standardised method of monitoring progress. The need to maintain OEE is particularly acute in a multi-use batch plant such as Seal Sands. Without effective monitoring, equipment faults can not only hold up a single batch but potentially shutdown a whole manufacturing plant.
To help us gather and analyse this data more efficiently, we decided to institute a complete procedural change by designing a computer based data capture and analysis system that would calculate the OEE for all of the plant equipment in “real-time”. We didn’t want to rely on traditional OEE systems which are paper-based and require data input and analysis after the event. We wanted a system that got to the root causes of problems much quicker, feeding information back to the operator immediately.
The OEE software was developed in-house by Paul Shields, IT Manager at Evonik Degussa Seal Sands, in close co-operation with our Operational Staff, to allow for more efficient data capture and analysis. Once we had the software we were still unsure how best to implement it on the manufacturing plants, especially in the hazardous areas. By working in partnership with Extronics we have managed to overcome the difficulties traditionally associated with our extreme environment and Zone 1 hazardous areas.
We tasked Extronics to provide an economical and scaleable system for our plant operatives to be able to enter data about the plant and equipment into the OEE system in many locations on the reactor floors of four production buildings. The OEE software requires a full screen (XGA resolution) PC terminal to enter the data, as Windows Mobile PDA’s were not suitable.
Initially our concept was to install several fixed Ethernet connection points. But the cost of installing this type of LAN infrastructure in a Zone 1 hazardous area and the future scalability meant this approach was far from ideal. Moreover, we specified that the network should allow for the future introduction of Windows Mobile PDA’s with barcode scanners for other data collection tasks.
Extronics reviewed the situation and our needs and consequently recommended that we install a WLAN. This option offered a more practical and cost effective solution for our immediate requirements as well as catering for the new applications that we were planning without any further infrastructure costs, whether that may be utilising PDAs, introducing RFID readers to gather data or using active WiFi RFID tags to track asset and stock movements.
Extronics provided its Meru-powered iWAP101 802.11a/b/g WLAN Access Points which are centrally managed and controlled and use a single channel architecture (rather than the traditional 1, 6, 11 channel planning approach). This provides the most robust and stable WLAN available for use in heavy metal environments that are notorious for suffering from the effects of RF multi-path interference. The data entry PC Terminals, also manufactured by Extronics, are based on GECMA Explorer 15i Touch panel PC’s with iWAP400 WiFi client bridge adapters to connect to the WLAN.
For the first phase of the project we opted to install a ring main around the plant with Zone 1 live disconnect power sockets so that the Mobile PC Terminals could be plugged in at convenient locations and connect to the network automatically allowing operatives to enter the data into the OEE server.
Extronics then undertook a site survey to determine the optimum location and number of iWAP Access Points required to cover the reactor floor areas with a high bandwidth 54Mbit/s WiFi network. Another key aspect of the RF survey was for Extronics to learn about the RF interference that is more often than not present in the plant.
Most process plants have unacceptable levels of background noise on one or more of the available 13 channels for the 2.4GHz WLAN spectrum, which will cause network connectivity and throughput problems if that channel is used. By using a single channel, the optimum one can be picked to avoid the interference. Also as the bandwidth requirements increase new Access Points can be installed without having to re-configure the network and channel planning. In all 7 Access Points were required to cover the four reactor floors which are centrally managed by a Meru 1015 controller.
The hardware was installed by our own engineers and the complete WLAN was set-up by Extronics’ professional services department in just one day.
Our Seal Sands plant has been able to improve production through working with Extronics. In a multi-purpose, multi-product batch plant such as ours, being able to measure and improve the overall effectiveness of our equipment was vital. However, rather than just spending time measuring our OEE we are now able to involve our people and concentrate our efforts on improving specific areas identified by the analysis tool, thanks to Extronics’ equipment.