Pulp, paper and wood

Improve manufacturing productivity at every stage

Vaisala's in-line dry solids content, and humidity and temperature measurement solutions support the sustainability and performance requirements of wood-based forest industry in a broad range of applications. Our technologies help paper chemical companies, kraft chemical and semi-mechanical pulp mills, and paper and wood mills achieve high efficiency and essential properties in pulp, paper, paperboard, wood and timber products. 

You may click on a link to discover supported applications and impact in each of these four categories: Pulp chemical recovery, brown stock washing, paper making and wood and timber processing.

Inline process control applications in the kraft chemical recovery

Although the kraft recovery process is straightforward in principle, it is not easy to operate at high efficiency without proper process measurements. We provide retractable Vaisala Polaris PR53SD Process Refractometers for measuring black liquor and green liquor dry solids, liquid density, concentration, and Total Titrable Alkali (TTA) in chemical recovery process to optimize energy-intensive operations. As a result, the capacity of the evaporators can be increased, and the quality of white liquor can be improved by controlling continuously the TTA of the green liquor in the causticizing process. Furthermore, recovery boiler safety can be increased using a Digital divert control system in feeding black liquor solids to recovery boiler burners.


Inline process control applications in fiberline and brown stock washing

Brown stock washing (BSW) can be considered the key operation influencing the economics of the pulping process, as well as the environmental load of the mill. The purpose of brown stock washing is to remove both organic and inorganic soluble compounds from the pulp suspension (brown stock), while using the lowest possible amount of wash liquor or water. Vaisala provides Process Refractometers for measuring and monitoring the Total Dissolved Solids (TDS) content in the pulp suspension. 

Through optimization of the brown stock washing process and raising the black liquor solids content, mills gain immediate profits, cleaner and better quality pulp for bleaching, as well as optimized use of water, chemicals and energy.


Inline concentration measurement of sizing liquids and humidity measurement in paper mill

In paper manufacturing it is important to control the paper sizing process as well as moisture content in the paper to an optimal level based on the end-use e.g. printing.

Vaisala provides Process refractometers for the preparation and use of the size liquids, to ensure the right concentration of the cooked starch to storage, and to help stabilize sizing conditions and paper quality.

Learn more about concentration measurements in paper sizing

Typically, the paper mass is not measured directly, but paper mills use the hood air measurement to monitor and control the drying process indirectly, to avoid excess humidity in the hood. This measurement is especially demanding if there is a risk of condensation combined with elevated temperatures.


Wood and timber drying

Wood drying is a complex process where measuring relative humidity plays an important role. Save energy and reduce costs by monitoring the humidity in your processes to avoid over-drying products and wasting energy. For accurate measurements, use the appropriate sensor, install the measurement device correctly, and calibrate the device regularly. Try our Drying Simulator below to calculate your cost savings or learn more about


Related assets

Expert article

From green to white liquor: How process refractometers can transform causticizing efficiency and quality

In the causticizing process, passive chemicals are converted into active cooking chemicals to make white liquor. This is used in the digester as a cooking chemical and needs to be of a high and consistent quality to maximize mill productivity. Accurate and continuous measurement of green liquor density or total titratable alkali (TTA) is essential to ensure this high quality is maintained. 

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Measuring Real-Time TTA/Density of Green Liquor in Pulp Mill Causticizing with Process Refractometers

In this webinar you will learn about different methods to measure and control Green Liquor TTA/density in the causticizing process. 

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The importance of brown stock washing and dissolved solids optimization for pulp mill efficiency​

TDS changes in the feed and outlet stock lines, as well as in incoming and outgoing filtrate lines, can be detected immediately.

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Real-life use cases on control practices and impacts before and after TDS technology implementation in brown stock washing

The focus is on how mills have identified bottlenecks and improved economics using Optimized Dilution Factor (DF) functionality. 

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Advantages of real-time dissolved solids content (TDS) measurement in fiber suspensions + implementation in individual BSW process steps and upper level process control

Experts will present advantages of real time dissolved solids measurement on specific focus points of the fiberline, as well as an optimization practice of the entire brown stock washing based on these unique measurement devices. 

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Importance of brown stock washing and digester dissolved solids optimization for pulp mill efficiency

In an optimal case brown stock washing removes as much dissolved solids as possible while using the lowest amount of wash liquor or water.

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Brown stock washing optimization

Did you know that Total Dissolved Solids (TDS) is the only measurement that accounts for both inorganics and organics? Learn about this measurement parameter for Brown Stock Washing.



Video Q&A: Brown Stock Washing (BSW) webinar series

In this video/blog, Kimmo Koivula and David DiCorpo will focus on questions in relation to refractometer measurement, product specifications, and installation. 

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