Emerson wireless devices protect hot tanks at Hunt Refining

  • October 29, 2008
  • Emerson Automation Solutions
  • Case Study
October 29, 2008 – Emerson Process Management’s Smart Wireless network is protecting hot asphalt tanks at the Hunt Refining Company,Tuscaloosa, Alabama. Several hot tanks at the refinery are fitted with wireless temperature transmitters as a cost-effective means of keeping control room operators informed of conditions inside the tanks. This enables them to maintain temperature uniformity in the tanks to prevent formation of “cold spots” where trapped moisture can lead to extensive damage with repairs costing up to $200,000 per tank. At Hunt Refining, operators need to keep asphalt at process temperatures above 212o F in about 10 tanks. This avoids formation of cold spots. When very hot asphalt (at 300 o to 400o F) is added to a tank, the hot fluid may “melt through” the currently stored asphalt and reach cold pockets where any moisture present can flash off violently. There is a real potential for tank roof failure if operators do not recognize these cold spots and take corrective action.A decision was made at Hunt to install temperature sensors in these tanks and connect the measurement data into the refinery’s distributed control system so cold spots could be avoided, and easily identified if they do occur. After analysis showed that traditional installation of wired monitors would be very costly, a trial of Emerson’s Smart Wireless technology was initiated. Three Rosemount wireless temperature transmitters were positioned 120 degrees apart around the outer circumference of the tank and one to two feet above the bottom. The Smart Wireless Gateway for these transmitters was located about 400 feet away near the I/O building with a repeater between the tank and gateway to assure reception of all signals transmitted on the self-organizing wireless network. Two-wire Modbus communication carries the temperature data from the Smart Wireless Gateway to the refinery’s distributed control system. Emerson’s AMS Suite predictive maintenance software is connected along with the Plant Information (PI) network, so the wireless field devices are added to all wired devices managed by this software. Wired or wireless, the data appears the same.“These transmitters just work; they don’t fail,” said Hunt Refining process control engineer Dennis Stone. “The wireless network proved its value. The installation was simple, and the transmitters came up immediately and talked with the gateway as soon as power was applied. The gateway was easily connected to the distributed control system via a 2-wire Modbus communication. Now, any computer with access to our Plant Information network can obtain this information.”Each wireless device on a self-organizing network 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 mesh network until a clear path to the Smart Wireless Gateway is found. Although the transmitters at Hunt Refining are spaced evenly around the tank and not within sight of each other, their transmissions easily “bend” around the tank and then on to the repeater and gateway.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. All of this happens automatically, without any involvement by the user, providing redundant communication paths and better reliability than direct, line-of-sight communications between individual devices and their gateway. 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. “This wireless technology proved to be so reliable and robust,” Stone said, “it has already been expanded with temperature monitors on more tanks networked to a second Smart Wireless Gateway. That gateway also receives transmissions from a single wireless temperature transmitter monitoring the water being returned to the Black Warrior River to be certain of compliance with environmental regulations.”About HuntHunt Refining Company is a petroleum refining and marketing company headquartered in Tuscaloosa, Alabama. The 52,000 barrel-per-day refinery, which is currently undergoing an extensive expansion, produces a variety of high-quality products including gasoline, and distillate fuels as well as industrial and paving grade asphalt.About Emerson Process ManagementEmerson Process Management, an Emerson business, is a leader in helping businesses automate their production, processing and distribution in the chemical, oil and gas, refining, pulp & paper, power, food and beverage, pharmaceutical, and other industries. The company combines superior products and technology with industry-specific engineering, consulting, and project management, and maintenance services to help customers achieve the potential of their operations. Emerson brands include PlantWeb, Fisher, Rosemount, Micro Motion, Daniel, DeltaV, Ovation, AMS Suite, and CSI.About EmersonEmerson (NYSE:EMR), based in St. Louis, is a global leader in bringing technology and engineering together to provide innovative solutions to customers through its network power, process management, industrial automation, climate technologies, and appliance and tools businesses. Learn More

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