For instance, Kane cites results at one BASF plant in which a hydro-carbon was mixed with a catalyst, heated and then oxidized. Before install-ing Honeywell’s SmartCET corrosion monitor, which provides online, real-time information and interfaces to a control system using HART, BASF could only assess corrosion problems offline. But within weeks after install-ing the multi-probe sensor, BASF correlated corrosion events with process events. Now such events can be correlated within seven minutes, allowing action to minimize corrosion.
Bayer Technologies Services, Baytown, Texas, uses a SmartCET cor-rosion monitor in a continuous, gas-phase reactor made of a molybdenum alloy, explains Chak Wong, an engineering consultant at the firm. The sen-sor’s probe is installed at the vessel’s inlet, where Bayer finds corrosion oc-curs more than elsewhere in the reactor. “The corrosion problem might be due to condensation, due to the phosphorous-based catalyst being used,” he says. “And it [corrosion] might be during backflow, when the unit is idle.” The estimated corrosion rate was 0.5 mils to 2 mils annually, measured by the SmartCET monitor during its first four months of use, Wong notes, which matches the acceptable annual rate of 1 mils to 2 mils.
However, one weekend, during a 30-hour period, the rate reached about 100 mils annually. “It was traced back to process condition during the idling period,” he explains. “And human error caused no nitrogen blanketing during that time.” The corrosion sensor’s observations matched almost one-to-one the actual operating conditions that caused the spike, adds Wong. The process conditions were changed to prevent further occurrences.
Currently, Bayer Technologies uses one Honeywell unit but is looking at installing another in a second, identical gas-phase reactor in the same op-erating unit, Wong says. “And we’re also adding some more SmartCET units in Baytown at another operating unit.” He adds that Bayer has many more such sensors installed at its European facilities.
Value for valves
Piping and vessels, of course, aren’t the only concerns at plants. The multi-tude of valves controlling flow also demand serious attention. “Today’s technology allows fault detection and analysis while the valve is in normal operation — i.e., online and in-service,” says Rhinehart.
Houston-headquartered Tapco International Inc., a subsidiary of Cur-tis-Wright Flow Control Corp., produces slide valves with smart-sensor technology for service with refinery fluid catalytic crackers (FCCs) and uses the TA-12 explosion-proof linear position transducer from Balluff GmbH, Neuhausen, Germany, in those valves. “We put it inside of a cylinder and that’s part of the actuator of all the slide valves we manufacture,” notes Dan Do, a Tapco project design engineer. “The TA-12 can also be used on butter-fly and plug valves.”
This transducer provides condition feedback — valve position — adds Scott Rosenberger, product-marketing specialist with Balluff USA, Flor-ence, Ky. “It mirrors what the actuator is doing and transmits that informa-tion to a device that has the intelligence capabilities to process that informa-tion.”
Tapco’s valves are part of the critical control for refineries and are ex-pected to operate continuously, Do explains. With the Balluff device, if a problem occurs with electronics in the transducer, it can be removed without interfering with valve operation. “We’re not allowed to depressurize and lose control of the valve,” Do says.
A wireless future
Wireless devices certainly seem set to play an increasing role. PPG, for one, would like to use wireless smart sensors more, Gerami says. “We’re jumping into the wireless arena like crazy. Wireless condition monitoring might be a great way to get started.” For process safety, he foresees wireless usage with equipment such as relief valves and rupture disks. Coupled with an acoustic or pressure sensor, the smart wireless device could show when overpressure protection has been actuated.
There’s also a need for a wireless smart sensor at a safety shower, he believes. “If someone is using it, that person is obviously in trouble. So it would be useful to know when it’s been actuated, so that we could send the response team to assist.”
Vendors certainly are responding by introducing more wireless smart devices. For example, ITT Industries Inc., Seneca Falls, N.Y., in December 2005 launched its PROSmart wireless machine-health monitoring system. Designed to replace traditional walk-around inspections of rotating equip-ment such pumps, motors, fans and compressors, the device collects, trends and displays data, as well as sounding alarms via cell phones, e-mail, pagers and a Web-based browser.
The chemical industry should keep its eyes focused on wireless, says Sierra, because its use is definitely due for a dramatic increase to enhance monitoring, control and asset management. “The reason is simple,” he ex-plains. “A 20-plus-year-old plant in Illinois will need to effectively compete with a brand new state-of-the-art facility overseas.”
But whether wireless or not, smart sensors will continue to gain stat-ure and usage in the chemical industry for good reason. “Smart devices have the intelligence to determine and communicate information about the asset’s health status, in addition to whatever else is communicated in their opera-tional role,” states Biddle. Worth noting: Those assets could include people, not just machinery.