AkzoNobel on Its Wireless Network at a Belgium Plant
Wireless Controls - Nicolas Delfosse, Process Engineer Surface Chemistry at AkzoNobel's surfactants processing plant in Belgium, explains why the lack of available I/O and high cable infrastructure costs have led the plant to adopt a wireless network based on the IEC 62591 (WirelessHART) standard.
Evolving government legislation, tight corporate environmental guidelines and a very competitive marketplace mean that AkzoNobel is continually looking to improve production processes. One way of achieving this is to gain a better understanding of each individual process by increasing the number of measurement points as well as automating existing measurements. This desire for new and more detailed information has to be balanced against the cost of adding the new measurement devices themselves and, just as importantly, the infrastructure that integrates this data into the existing distributed control system (DCS).
AkzoNobel's surface chemistry plant in Ghlin (Mons), Belgium, produces fatty nitriles and amines, which are stored in 40 tanks in the tank farm area of the plant before they are shipped to customers. When loading final product into road tankers, it is imperative that the fatty nitriles and amines are maintained within specific temperature parameters. Too cold and the products are difficult to handle; too hot and the quality of the products can be affected. Steam is used to heat the tanks, usually starting a few days before a load is due to be collected. Previously, this task required one of the company's operators to manually open a steam valve to begin the heating process.
No existing temperature measurement devices were in place on the tanks; the company merely used operator experience to determine when to start heating. The company then took manual temperature readings at the main outlet valve, if the product was too hot the steam valve would be closed; if the product then cooled too much the valve would be opened and heating restarted.
This manual control was unsatisfactory, and a number of customers complained that the delivered product was too hot. AkzoNobel was therefore very keen to automate this process by introducing a simple closed-loop heating control. However, the company faced a number of challenges to doing so, including a lack of cable infrastructure, a lack of available I/O, and tight budget constraints.
Wiring Complications
Initially the company considered fieldbus for this application, but that approach would have incurred significant cabling infrastructure costs, requiring trenches and cabling between the tanks and the control room over distances of 200 m.
Another major issue was the lack of available I/O in our control room. Only a small amount was available, and with future modifications and additional measurement points planned, the company did not want to use it all for this project.
One option was to modify the existing DCS system and control room, but this would be expensive and also created the risk of the control system being brought offline for a period of time. In addition, there was not enough room for the additional cabinets required. The combined cost of the cable infrastructure and the required DCS changes made the project unfeasible if the company were to adopt any form of wired solution.
Wireless Options
AkzoNobel identified wireless as the perfect alternative solution. Adopting a wireless solution would eradicate the need for digging trenches and installing cable trays to house the new power and data cables. Equally important, the data from the wireless transmitters could be fed via a gateway directly into the existing DCS without consuming any I/O.
The company also recognized that wireless offered benefits beyond this first project, especially the ability to expand the network by adding new devices quickly and at little cost compared to wired devices. With a continuous programme of process improvement at the plant, the company anticipated that more devices would be added at some point in the near future. Implementing a wireless network now would create an opportunity for installation savings every time a device was added in the future.
A number of wireless options were considered, but the company was keen to adopt an open standard technology that would not tie them to a single vendor. This would enable multi-vendor installations, selecting the best instruments for each measurement task. The approval of IEC 62591 (WirelessHART) by the International Electrotechnical Commission (IEC) gave the company the confidence to adopt this international wireless standard. AkzoNobel selected Emerson Process Management's Smart Wireless solution for these applications for a number of reasons.
Emerson's Smart Wireless is based on IEC 62591 technology. This means that once the network is commissioned the company can install devices from any vendor as required. The company was also particularly impressed by the number and range of existing implementations of Smart Wireless around the world. Emerson's experience was far in front of other vendors, and this experience gave AkzoNobel great confidence with its own application.
Smart Wireless Solutions
Four of Emerson's Rosemount WirelessHART temperature transmitters have been installed so far to control the temperature of a number of the storage tanks. From these devices, measurement data is transmitted every minute to a wireless gateway and is then integrated into the existing DCS. The DCS then automatically controls a simple On/Off steam valve that heats the tanks.
The temperature of the tanks can now be maintained using this wireless closed-loop control, enabling us to ensure that the final product is delivered within the appropriate temperature parameters. By automating this process, the company removed the requirement for the operator to go into the field and manually operate the steam valve to get the desired result.
This has allowed the operator to focus on higher value tasks. AkzoNobel also gained much tighter control over the amount of steam used. Although they have yet to calculate the impact of this improvement over a long period, they know that there is a significant reduction in steam consumption, which will create a saving on their operating costs.
Expanding The Wireless Network
A second application for automating pressure monitoring on the company's venting system would also have required new cable infrastructure to be installed. This application was necessary to meet their corporate guidelines and new local environmental legislation requiring chemical processing companies to monitor and control all gas emissions.
Ammonia gasses and organic vapors are produced from the fatty nitriles and amines stored within the tanks. These gasses are collected via a venting network and then incinerated. In addition, gasses are collected via the same vent network from large basins that hold storm water and process water. To identify any blockages in these vents, pressure is monitored, with any drops below the level of atmospheric pressure indicating a potential problem. Previously, the company used manual gauges that required an operator to make regular trips into the field to take "snap-shot" readings.
This was time-consuming and failed to provide the continuous and immediate information the company required. A total of ten Rosemount WirelessHART pressure transmitters have been installed to replace the gauges. Again, by automating the measurements, the company has improved the efficiency of its operators by enabling them to focus on higher value tasks.
The continuous pressure data the company are now receiving has enabled us to identify blockages immediately, and the company solve this quickly by flushing the vents. A third application presented itself almost immediately. It had become apparent that additional thermal measurements were required from within the venting conduits. This information would be used to prevent potential fires arising from the high temperatures.
In this application, an important issue was the short timeframe available to install the new devices to obtain these additional measurements. The company was keen to do so before the next government inspection, which would have been very difficult to achieve if we had proceeded with a wired solution. The established WirelessHART network enabled them to install three Rosemount WirelessHART temperature transmitters quickly and easily. These devices provide us with the required temperature information and will raise an alert in the control room should levels rise above preset limits. Adding devices is so simple that one could describe the Emerson Smart Wireless solution as "plug and play." Once the devices are in place, they quickly connect with the network and operators can view data almost immediately.
Results And Future Applications
AkzoNobel estimates overall savings from adopting a wireless solution instead of installing cabling and making changes to the DCS to be approximately €180,000. Because of the success of the initial applications, the company intends to upgrade the temperature gauges on all 40 storage tanks.
The company is now also considering a number of other applications at the Mons site. New legislation requires redundant automated level monitoring technologies to be applied to ensure against overfilling. They plan to make use of the wireless network again when implementing Emerson's Rosemount wireless vibrating forks that will identify levels in tanks to help provide overspill protection.
Another application being considered is a drain switch system on the gas venting line. Here wireless vibrating forks will be used to monitor condensate levels in the venting system. When these reach a certain level the vents will be drained automatically. The company is even considering the possibility of using wireless to help us monitor the position of existing process valves. To ensure against tank filling errors, the company would like to bring currently unavailable position information from a number of manual valves into our DCS. Here, Emerson's wireless position monitor will forward the stranded position information.
