Self-organising wireless network reduces installation costs and enables online monitoring of vapour pressure and levels in tanks
Emerson Process Management announces that its Smart Wireless technology has been installed by Nynas AB to upgrade an underground storage tank monitoring system, creating an online integrated solution and reducing installation costs by €10,000 compared to a wired alternative. Nynas is an international group that refines heavy crude oil to produce bitumen and naphthenic speciality oil products. The company owns four refineries, one of which is located at Nynäshamn in Sweden. The underground storage tanks at Nynäshamn are monitored for unequal vapour pressures which can indicate potential blockages in the pipes that connect the tanks. The existing pressure switches are ageing and due to be replaced. They were not continuous, only indicating when set levels had been exceeded.
“When a signal cable on one of the switches failed we decided to upgrade to an online solution that would bring storage tank measurement data directly into the plant’s control system and help identify blockages much earlier,” said Morten Hansen, Senior Instrument Engineer, Nynas. “We were also interested in trialling wireless technology and this application presented the perfect opportunity.”
The underground storage tanks are located a considerable distance from the control room and if Nynas had installed conventional instrumentation, new cabling would have been required to connect to the remote devices. The cost of this was prohibitive so Nynas looked at the benefits of using wireless.
With no line of sight between the location of the pressure transmitters and the ideal position for the gateway, Nynas selected Emerson’s Smart Wireless products, which use self-organising technology, to connect the devices. With this 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 Smart Wireless Gateway is found. The technology also offers redundant communication via two or three routes ensuring greater than 99 percent communication reliability.
Two additional Rosemount® wireless pressure transmitters provide measurements from the very large underground storage rooms (bunkers) containing crude oil. Measurements are taken to identify unequal vapour pressures in the different sections of the bunker. Data is transmitted every 60 seconds to a Smart Wireless Gateway located 650 metres from the pressure transmitters. The Gateway is connected to Emerson’s DeltaV™ digital automation system using Modbus communications.
A further two Rosemount wireless transmitters installed on large vessels within the facility act as repeaters providing additional routes for the data and ensuring reliability of connection. Additional wireless measurement devices can be easily added as required and, by increasing the number of routes available to send data back to the gateway, they make the network even more reliable.
“Using Emerson’s wireless solution we have been able to significantly reduce the cost of upgrading the pressure measurement to an online system. Installing new cabling would have cost €10,000 more than the wireless solution,” said Hansen
”Installing the Emerson devices onsite was relatively easy and it took less than a day to complete the configuration and start-up procedure.” he continued. “We have also found the technology easy to use with the ability to manage the devices using Emerson’s AMS™ Suite predictive maintenance software.”
Having successfully trialled the Smart Wireless technology, Nynas has expanded the wireless network at the site. Rosemount® Rex radar level gauges, equipped with Smart Wireless THUM™ adapters have been installed, replacing two existing mechanical servo gauges. A technology change of this type would normally require the replacement of the signal cables, but by using a THUM adapter wireless communication is added to the instrument, thereby avoiding the need for expensive cable installation.
The THUM adapter is a WirelessHART™ device that can retrofit on almost any two or four wire HART device, without special power requirements, to enable wireless transmission of measurement and diagnostic information. Devices with the THUM adapter operate as components of Emerson’s Smart Wireless self-organising field network.
Smart Wireless is an extension of PlantWeb® digital architecture that offers solutions for field instrumentation and plant operations. In addition to the products installed at Nynas, other Smart Wireless products available include Fisher® position monitors, Rosemount Analytical devices and Machinery Health™ Management transmitters, and native wireless interfaces to Ovation® digital automation systems, and SmartStart® services.
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