Wireless transmitters

FH Tank Storage AB is using wireless level and pressure transmitters, a plant-wide wireless network, digital automation system, and predictive maintenance software to automate tank storage level monitoring and provide overspill protection at its Kalmar storage terminal on the east coast of Sweden.

The Smart Wireless network has enabled measurement data to be processed without the need to install new cabling, a cost saving of between €50,000 and €100,000. New cabling would require extensive groundwork which would disrupt operations and fuel tanker traffic around the site.

The Rosemount transmitters are deployed on the storage tanks and transmit measurement data to the DeltaV system installed in the main control room. AMS Suite helps operators monitor the health of both the wireless network and the individual transmitters, and improves the efficiency of maintenance staff by identifying any faults and reducing the number of trips into the field.

“Emerson’s Rosemount level, pressure and temperature transmitters, and the Smart Wireless network, have enabled us to implement a cost-effective automated measurement system,” said Lars Ferm, Site Manager, FH Tank Storage. “They have also improved the monitoring of tank levels and have provided a fully approved overspill protection solution.”

The FH Tank Storage terminal has a capacity of approximately 13,000m3. The 68 tanks, ranging in size from 10 up to 2100m3, are used to store solvents, petrol and a range of chemicals. Increasingly tight environmental regulations required overspill protection to be added to all existing tanks, with new level switches needed to trigger an alarm should levels rise above preset levels.

Previously, tank level measurements were performed manually. This required operators to climb to the top of tanks in challenging winter conditions, putting them at risk of injury. The monthly checks took a whole day and involved the use of dipping ropes, calculating volumes, and updating a white board in the main control room. Although a rigid set of procedures was in place to ensure accuracy and reliability of measurements, FH Tank Storage wanted to automate these measurements to reduce risk and remove any potential human error when recording, calculating and listing tank levels.

Emerson proposed the implementation of a continuous automated measurement solution using the PlantWeb digital architecture and Smart Wireless technology to transmit accurate and up to date tank level measurements that could also be used to provide overspill protection. Rosemount devices deployed on 29 tanks transmit level and temperature data back to the latest versions of the DeltaV system and AMS Suite software installed in the main control room. A large screen provides operators with visualisation of all the tanks, tank levels and any high level alarms or instrumentation failures. The solution was presented to and accepted by Länsstyrelsen, the Swedish local environment and safety authority.

FH Tank Storage wanted to minimise the different types of devices installed, to enable easier maintenance and reduced inventory. For the smaller tanks, FH Tank Storage installed Rosemount 3051S wireless DP pressure transmitters. The pressure measurement of the liquid's mass and the media's density is used to derive level. The devices transmit data every minute.

A number of the larger tanks have floating roofs, making it more difficult to install DP pressure transmitters, so Rosemount 5402 non contacting radar level transmitters have been deployed on the larger sized tanks. Smart Wireless THUM Adapters are connected to each of the radar devices to transmit the data via the wireless network. The Rosemount 5402 was selected because it is suitable for almost all tank sizes, is unaffected by floating roofs, and is suitable for a broad range of liquids and gases. Measurement accuracy is not affected by dirty or corrosive liquids or by fluid properties such as density and viscosity.

“The Smart Wireless network was relatively simple to install and both the network and the transmitters have been extremely reliable since they were installed,” explained Ferm. “We expect to continue to deploy wireless level devices in the near future as we don’t see any reason or benefit to using cables.”

There have been no overfill alarms at the site so far, and the historical information provided by the radar measurements has enabled quick and accurate answers to customer queries. Based on this success, FH Tank Storage has placed a further order for Rosemount radar level transmitters and THUM Adapters to automate 15 more tanks. In addition, 5 tanks are currently being constructed at the terminal and Rosemount radar devices are expected to provide the level measurements and overspill protection.