pH Products & Information

Current Challenges and HH SCIENCE’s Solutions for pH Sensors in FGD Applications

1. Contamination of the Ag/AgCl Reference Wire
In traditional pH electrodes, sulfur compounds present in flue gas desulfurization (FGD) slurry can penetrate the liquid junction and react with the Ag/AgCl reference wire. Once contaminated, the reference system becomes unstable, leading to noticeable pH drift, requiring immediate replacement of the sensor.

2. Rapid Electrolyte Depletion
The reference system in pH electrodes operates on galvanic cell principles. Slurries such as lime and gypsum used in wet limestone-gypsum FGD systems significantly accelerate electrolyte consumption, dramatically shortening electrode service life.

3. Fouling and Breakage of the Glass Electrode
FGD slurries are highly prone to coating the glass bulb with suspended solids, leading to measurement inaccuracies. In high-limestone-content conditions, abrasive particles can cause physical damage to the glass membrane, such as cracking or pitting.

HH SCIENCE’s Teflon pH Electrode Solution for Desulfurization
As illustrated, the HH SCIENCE Teflon pH electrode adopts a solid-state, microporous reference system, unlike traditional porous ceramic junctions. It uses a highly stable polymer-based Teflon interface as the contact point between the reference system and the process medium. This design provides the following technical advantages:

1. Larger Reactive Interface Area
The entire outer surface of the polymer interface acts as the electrochemical junction, offering a much larger contact area than conventional porous junctions. This results in faster response times.

2. Superior Anti-Clogging Performance
The microporous Teflon structure is far less prone to clogging than traditional porous ceramic or fiber junctions, enhancing reliability in particulate-laden slurries.

3. Low Maintenance, Long-Term Stability
The Teflon electrode encapsulates the pH glass membrane within a high ionic-activity, symmetrical micro-diaphragm structure, replicating the benefits of conical junctions without their susceptibility to turbulence-induced scaling, thermal shock, or KCl depletion.
This design eliminates the need for regular maintenance and protects the reference from fouling, poisoning, or electrolyte degradation, ensuring stable and extended measurement performance.

4. High Pressure Resistance
The mechanical design of the Teflon electrode allows it to withstand pressures up to 10 bar (recommended up to 6 bar), making it suitable for demanding industrial applications.

5. Extended Service Life
Field data and testing show that the Teflon pH electrode’s lifespan exceeds that of conventional electrodes by at least 3 times, significantly reducing replacement frequency and total cost of ownership.