The wireless transmitters are positioned up to 150m from the gateway
The filters gradually become blocked and lose their efficiency, which in turn affects the quality of the end product. INEOS could have established a preventive maintenance routine and cleaned the filters on a time-based schedule. However, such a schedule could mean that filters are cleaned when they do not need it or that filters could block between cleanings.
Cleaning and unblocking the filters requires INEOS to stop the blowing, which is not good for the process. Should blockage occur on a weekend, the maintenance costs are higher.
INEOS chose to clean the filters on a predictive basis, cleaning them before they become blocked and lose too much efficiency. By closely monitoring the filter condition, the maintenance team can schedule the cleaning work at a time that will minimize the cost and disruption caused.
A liquid column (U-tube) was installed across the filter, indicating the differential pressure. An increase in the pressure suggests that the filters are blocking. However, because the compressors blow discontinuously, it is not always easy to spot when a filter is blocked. In addition, manually checking and recording the results is a time consuming task that had to be undertaken daily.
INEOS explored the possibility of installing an on-line system that would closely monitor the condition of the filter and ensure its availability. Using differential pressure meters makes it possible to monitor the condition of the filters on-line. However, because of the location of these filters, connecting the required measurement points back to the control system using a wired solution was not feasible. Cabling would need to be installed in areas that were difficult to reach, and the cost of a wired solution was too high.
"The filters are hard to reach and the high cost of installing cabling to connect the devices prevented us from installing the on-line condition monitoring points we wanted," explained Frank Mehlkopf, maintenance engineer, INEOS Köln GmbH.
INEOS also wanted to minimize the installation time, so wireless was an attractive option. INEOS looked at a number of wireless technologies for this task, but found that line-of-sight solutions could not provide the reliability of connection or the robustness they required. The transmitters needed to be positioned in a dense working environment with many metal obstructions that can cause interference. A large amount of moving equipment could also cause temporary loss of signal for line-of-sight wireless solutions.
Wireless technology is enabling INEOS to detect blocked filters within polyethylene pellet transportation tubes that can lead to production downtime at its plant in Cologne, Germany
INEOS installed a robust smart wireless network including eight wireless transmitters. Via a single gateway, the eight wireless transmitters send the pressure data back to the control system, where the condition of the filters can be constantly monitored. The transmitters are positioned up to 150 m from the gateway.
Using self-organizing technology, each wireless device can act as a router for other nearby devices, passing messages along until they reach their destination. If there is an obstruction, transmissions are simply re-routed along the network until a clear path to the gateway is found. As conditions change or new obstacles are encountered in a plant, such as temporary scaffolding, new equipment or a parked construction trailer, these wireless networks simply reorganize and find a way to get their signals through.
All of this happens automatically, without any user involvement, providing redundant communication paths and better reliability than direct, line-of-sight communications between individual devices and a receiver. This self-organizing technology optimizes data reliability while minimizing power consumption. It also reduces the effort and infrastructure necessary to set up a successful wireless network.
"We found that Smart Wireless was so easy to install and commission," said Klaus Dieter Kleinert, Engineer, INEOS Köln GmbH. "We were wary of having to undertake a time consuming site survey for wireless installation. We will consider this technology in further projects in comparison to our previous installation standards."
Predictive maintenance software was used to manage the new wireless devices, enabling the technicians to configure the devices, run diagnostic checks and monitor alarms and alerts.
"We are currently testing [the wireless network] at eight filters in our logistic area," said Mehlkopf. "One of the main attractions of the solution is the ease in which you can expand the network. It is possible to add additional transmitters to the existing wireless network without having to add additional gateways. These transmitters do not even need to have line of sight to that gateway as the other transmitters pass on the data back to the control system. We fully intend to take advantage of this."
The wireless network has been up and running without any problems for eight months. INEOS intends to further expand the wireless installation with the introduction of vibration monitoring.
Pumps & Systems, November 2009