New Radar Level Sensor Copes with Severe Sulfur Environment
A Rhodia chemical plant in Houston had a critical problem—how to measure the amount of molten sulfur in a vessel critical to plant functions. The plant makes and regenerates sulfuric acid. Every day, a logistics technician had to climb atop the 32-ft sulfur tank, open the lid and take a manual measurement of the 300°F molten material.
It was a smelly, time-consuming task, and it provided no safeguard against the level dropping below a critical point. Sulfur constantly flowed in and out of the vessel. If the level dropped too low, it would force a halt in one section of the plant for 10 hours or more.
Rhodia instrument and electrical supervisor Terry Ray wanted to install a noncontact sensor that would protect against process failure. An ultrasonic device was not an option because of heavy steam and hydrocarbon vapor in the tank and the fact that anything inside the tank would soon be coated with crystalline sulfur.
Ray considered installing a radar device, but the cost seemed prohibitive, and radar had caused him headaches in the past, due to complicated adjustment. "I'd tried another brand of radar on other applications, but it was expensive and not user-friendly," he said. Ray learned about a new radar device from Milltronics (Arlington, TX) and agreed to test it on the sulfur tank.
Ray found that the installation of the IQ Radar 160 took only 20 min, similar to other Milltronics ultrasonic devices. Recalibration of the device's location to correct a measurement error took minutes.
In operation, Ray said that the unit has been consistently within 1 in. of the daily manual measurement. In fact, by comparing the radar's output against that of the two technicians who normally measure the tank, he found an inconsistency in the technicians' procedures. He is now preparing to wire the radar's output into the plant control room so that operators will have the sulfur reading on hand.
The IQ Radar 160 uses a patented, pulse-based microwave technique to deliver continuous, noncontacting level detection. It is unaffected by stratified vapors and foam. Because it generates a signal within the lower range of the microwave spectrum, the unit is able to use a relatively large antenna that is unaffected by buildup or encrustation. The pulsed signal delivers a strong return signal, even in "busy" tanks where paddles, agitators and foam can absorb microwave energy. It incorporates a dielectric resonator to avoid the frequency-stability problems commonly associated with other pulse technology products. Milltronics' proprietary Sonic Intelligence echo analysis software ensures that readings are reliable by filtering out extraneous signal returns commonly found in process and reactor vessels.
Edited by Nick Basta
For more information: Milltronics Inc. 709 Stadium Drive, Arlington, TX 76011. Tel: 817-277-3543, fax: 817-277-3894.