Figure 1: Stable readings were achieved with vibration during validation experiments.
Proof of Concept To validate our device, testing was performed with both intermittent and continuous vibration. This experiment was performed using a rotating bowl mixer with a plow blade. We used a 5 L bowl containing SuspendaSlurry FS (Ransom & Randolph) that was continuously rotated, both with and without the vibration activated. The vibrator in this design is pneumatically operated. Viscosity and density were recorded over time, with cleaning vibrations alternating between 25 minutes off and 25 minutes on. The experimental data (see Figure 1) confirmed that when the vibration was off, viscosity and density readings fluctuated. However, with vibration, the readings stabilized. This demonstrates that the selected frequency and amplitude do not interfere with measurement accuracy. Furthermore, the vibrating self-cleaning viscosity and density sensor provided stable and repeatable measurements. A manual density check was performed to ensure that the low-frequency cleaning vibrations did not affect measurement accuracy.
Field Trial For additional validation, field trials were conducted in operating shell rooms. SlurrySense sensors have been running continuously without deposits forming on the sensors. Plant operations continued normally: data was acquired using efflux cups and the SRD in parallel. Sample data from field trials (see Figure 2) show that the sensor could detect evaporation events over weekends and holidays, as well as dilution events, which appear as drops in viscosity. Throughout one month of operation, no cleaning or inspection was required to maintain sensor accuracy. Additionally, density measurements remained consistent over the same period. These results confirm that our sensor provides accurate data, and when compared with efflux cup measurements from the same facility, the viscosity trends observed with the SRD sensor aligned with those recorded by the efflux cup (see Figure 3). Figure 3 demonstrates that after a period of evaporation,
both the efflux cup and SRD viscosity measurements were elevated. Once water was added, the viscosity readings from both methods dropped accordingly. This confirms that the
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Figure 2: Sample measurement data for SlurrySense operation during a 1-month period without cleaning
Figure 3: Representative SlurrySense measurements for a slurry plotted alongside representative efflux measurements.
SRD viscosity measurement is capable of following efflux cup trends and can be used for process control, even in deposit- prone slurries.
Conclusion In summary, we have successfully developed a self-cleaning sensor that prevents deposit formation while maintaining compatibility with existing sensor technology. The vibration of the viscometer and density meter operates simultaneously with the continuous readings with reliable data. Field trials have demonstrated that it does not disrupt tree dipping operations and remains deposit free in deposit prone slurries.
Outlook The outlook for the SlurrySense in shell room viscosity and density control is promising. This self-cleaning technology extends the application of the Rheonics SRD sensor into deposit-prone slurries without excessive cleaning requirements. It reduces reliance on manual measurements and minimizes cleaning time for operators. Furthermore, the reassurance that the device remains clean increases trust in in-tank viscosity and density measurements, aligning well with efflux cup readings, dilution events, and evaporation observations.
April 2025 ❘ 43
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