Wet gas scrubbers are devices for controlling air pollution that use an injected liquid stream (water or a chemical solution) to remove pollutants from exhaust gas. They absorb pollutants into the liquid and neutralize them, preventing them from being released into the atmosphere.
Wet gas scrubbers are highly effective at capturing particulates and soluble gases, such as sulfur dioxide (SO2) and nitrogen oxides (NOx), to neutralize air pollutants. To operate effectively and efficiently, they also require accurate, repeatable wet gas flow rate measurement in harsh exhaust gases as they enter the system’s moisture-saturated air.
Moist or wet gases present a measurement challenge for almost all gas flow meter sensing technologies. For example, pitot tube-type flow meters can clog in these applications and require frequent, time-consuming cleaning cycles to achieve accurate, repeatable flow measurement. For this reason, plant engineers and pollution control systems suppliers often contact FCI about replacing pitot tube flow meters in their wet gas scrubber units.
As an example, the gas scrubber operating conditions under which flow meters typically perform include wet gas (air with 2% moisture) in round pipes line sizes of 15 to 54 inches (381 to 1371.6 mm). The flow range generally requires measurement over a broad range of 66.56 to 100,000 SCFM under process pressures of 5 psia in H2O (g) at temperatures of 70 to 95°F ( 21.1 to 35°C).
To support these needs, FCI’s ST80 Flow Meter is often chosen because it is a high-performance, thermal dispersion air/gas flow meter. It combines feature-rich electronics with a wide selection of application-matched flow sensors, including FCI’s unique AST™ thermal measuring mode and Wet Gas MASSter shield, which shunts moisture away from the flow sensor.
ST80 Thermal Flow Meter in Wet Gas Scrubber Applications
ST80 Flow Meters feature FCI’s patented no-moving-parts flow element designs that provide direct mass flow measurement with just a single process penetration. This saves space and eliminates unnecessary installation, expense, and performance degradation associated with separate temperature and pressure sensors, and density calculation devices needed with inferred mass flow techniques.
With no moving parts to plug or foul, the ST80 Flow Meter delivers extensive cost savings over alternative high-maintenance technologies. The result is an accurate and highly repeatable mass flow measurement at the lowest total installed cost. In today’s complex process control schemes, the ST80 Series provides accurate gas flow measurements essential for process consistency, quality and safe plant operation.
The wide-ranging ST80 Flow Meter is frequently chosen for wet gas scrubber applications because of its 1,000:1 turndown flexibility with accuracy of ±1.0% reading, ±0.5% full scale, and repeatability of ±0.5% reading. It combines these features with a robust transmitter enclosure for ease of installation and the longest service life.
The ST80 Flow Meter is offered in three styles: (1) no display, (2) with display, or (3) with display and user interface buttons. This display is a best-in-class device, with a backlighted information LCD. It provides users with both digital and bar graph readout of the process flow rate and temperature, totalized flow, alarm trips, user user-defined label field, and a fault indicator.
This meter is available with HART communications, which is a popular choice for wet gas scrubber applications and in many others. Users may also choose from other protocols as well, including Foundation Fieldbus, PROFIBUS PA, PROFIBUS DP, or Modbus.
The rugged ST80 Thermal flow meter is designed for use worldwide and is available with numerous agency safety approvals. They include FM/FMC, ATEX, IECEx, UKEX, EAC/TR CU, NEPSI, EMSA EQM-Ex, CE Mark, UKCA, CPA, CRN, SIL1
A DwyerOmega brand, FCI delivers precise flow and level instrument measurement solutions using advanced thermal dispersion technologies. With more than 60 years of experience and the world’s largest installed base of thermal flow meters, flow switches, and level switches, FCI is the trusted expert in flow and level instrumentation.
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