Handling slurries (a mix of solids and liquids), should be based on experience and experiments, not theory. Much of the knowledge obtained from pneumatic conveyors and fluidization systems can be used in understanding slurries.
Author: Thomas R. Blackwood, Healthsite Associates
This article looks at six technologies mechanical floats and displacers, differential pressure, capacitance, ultrasonic, radar, and guided wave radar that are used most often for automated control, and provides practical guidance for choosing among them.
Author: Jerry Boisvert, Siemens Energy & Automation
Theres more to boiler level control than measuring level and adjusting a feedwater valve. Improved measurements and inverse response are just a few of the influences on operating boilers in a reliable manner.
The new sampling/sensor initiative (NeSSI) is moving steadily to fulfill its original promise of increased efficiencies, costs-savings, and micro-analytic capabilities despite recent growing pains related to fieldbus.
Properly accounting for how bulk solids actually will flow in a vessel or overall process can be crucial for successful operations. Learning some simple parameters can often provide a good sense of flowability.
Author: Don McGlinchey, Glasgow Caledonian University
Theres no simple solution to achieving accurate temperature measurement. Its a combination of knowing the inherent accuracy of particular sensor types, and how environmental factors can create further measurement uncertainty and the sensor calibration techniques available to reduce this uncertainty.
Author: Cal Swanson, Watlow Electric Manufacturing Co.
Changes in liquid densities can throw off readings. Plants commonly rely on differential pressure (DP) cells to measure level. Read this month's Plant InSites for advice on how to solve these level problems.
Sensors now can provide data on both general and localized corrosion that allow corrosion to be treated as a real-time process variable. Using such data effectively can play an important role in optimizing plant operations.
Author: Dawn C Eden, David A Eden and Russell D Kane, InterCorr International, Inc., Houston, Texas