Flow and Concentration Measurement of Process Water and Spent Liquor

Pulp is the output material for the production of paper as well for the production of sanitary products such as nappies or tissue paper. The primary raw material for pulp production is wood. To obtain the cellulose fibres contained in the wood, it is mechanically cut up into wood chips. These wood chips are then chemically digested under considerable pressure and at temperatures of around 150 °C in a continuous apparatus for boiling cellulose, where the binding agent lignin is released and removed. Flow measurements are required for process control.

In addition to wood and white liquor, water is also a very important raw material for pulp production. Usually, pulp mills pump the required water in significant quantities from nearby reservoirs and wells.

Equipping these raw water as well as process water lines with a FLUXUS non-invasive ultrasonic flow meter means, that there is no need to interfere with the existing piping system and as a result there is no need to interrupt the supply or service. The clamp-on ultrasonic technology not only saves considerable costs associated with expensive pipe works required for installing inline meters, but the non-invasive technology for these nominal widths is also significantely cheaper than e.g. magnetic inductive flow meters, as well as completely resistant to deposits forming inside the pipe.

A rather challenging flow measurement task in the paper production process is the measurement of spent (black) liquor: the prevailing, highly corrosive conditions regularly damage inline flow meters, such as magnetic inductive devices. As a result, these meters do not achieve a satisfactory service life. As the ultrasonic transducers of the FLUXUS do not get into contact with the aggressive medium flowing inside the pipe, it means that the system is not subjected to wear and tear and thus practically maintenance-free and very durable, offering a virtually unlimited service life.

Moreover, when employing FLEXIM's non-invasive ultrasonic process analyser PIOX S, the measuring system monitors - additionally to the mass flow rate - also the concentration of the white / black liquor directly from the pipe wall outside.

Advantages

Reliable, non-invasive (volume and mass) flow as well as concentration measurement, even under difficult measurement conditions
Easy installation and start-up without pipe work or process interruption
No wear by the medium, No risk of leakages
Highly cost effective - no process shut-downs required, virtually maintenance free and pipe size independent