Maintaining pH Accuracy in Extreme Process Conditions — Significantly Reducing Chemical Usage & Ensuring Quality Pulp

Pulp bleaching pH monitoring is very challenging for pH electrodes due to plugging and chemical attack. The pulp consistency can easily reach 10% and quickly plug the junction of the many pH electrodes. The pH range of the pulp changes drastically several times during bleaching. This alternating chemical process yields extreme pH values of around 3.5 in the chlorine dioxide (ClO2) stage and a value of around 11.5 during the caustic (NaOH) stage.

The Solution

The PL H-93 Memohsens pH sensor is the perfect sensor to use in pulp bleaching ph applications. The design is ideal for environments with suspended solids. The sensor’s Teflon™ annular junction is resistant to pulp stock. The KCL storage rings slow down the poisoning of the Silamid® reference system, thus extending sensor life. Lastly, the pH glass bulb works accurately in high alkaline and acidic environments.
To avoid extended exposure to the process, technicians can conveniently calibrate Memosens sensors, like the PL H-93 prior to installation. Offline calibration and sensor diagnostics can be performed using a Portavo 907 Multi portable analyzer. This ensures a more reliable sensor performance.
The microprocessor in the Memosens sensor head stores calibration data. The technician can simply carry it out to the transmitter, disconnect the existing sensor, and do a “hot-swap”. Additional calibration or configuration is not necessary. As a result, the pre-calibration significantly reduces downtime.
When a sensor needs to be replaced, the SensoGate WA 131 retractable holder enables quick and safe service to the pH loop. The holder completely retracts the sensor and shuts it off from the running process. Consequently, it ensures that there is little chance the operator will come in contact with the process.
The Stratos Evo transmitter is Memosens compatible. The Memosens sensor automatically shares calibration information from Memosens sensors with the transmitter. The system is ready to measure without any additional programming. The operator can retrieve diagnostics data at-a-glance from the Stratos Evo.
M4 Knick provides a comprehensive digital system for the bleaching process, maximizing safety and reliability in extremely challenging process conditions.

What was this Customer’s Return on Investment?

• Reduced chemical costs: Because the PL H-93 operates in very high alkaline and acidic environments, the accuracy of the sensor prevented the mill from excessive chemical usage, saving the paper mill a significant amount of money each year.
• Increased sensor life: The design of the PL H-93 reduced the wear and poisoning typically seen in extreme pH pulp applications. Memosens smart digital technology greatly reduced the need for calibrations as well as minimized sensor replacement which significantly lowered sensor costs.