Process Refractometers in The Kraft Pulping Process

Process refractometers are optical instruments that measure the refractive index of a substance to determine its concentration. They are widely used in the pulp and paper industry, particularly in the Kraft pulping process, to measure the concentration of essential chemicals in white, green, brown and black liquors.

The kraft process, which employs sodium hydroxide (NaOH) and sodium sulfide (Na2S) to convert wood into pulp, is the predominant pulping technique in the pulp and paper sector. This method is responsible for an annual production of approximately 130 million tons of kraft pulp worldwide, contributing to two-thirds of global virgin pulp output and over 90% of chemical pulp. Kraft pulp's superior strength, the process's compatibility with nearly all types of softwood and hardwood, and its economic benefits stemming from a high chemical recovery efficiency of about 97% make the kraft process more favorable than alternative pulping methods.

Process refractometers apply in the following steps of the Kraft pulping process:

• Green Liquor Control: After burning the black liquor, the resulting green liquor contains sodium carbonate (Na2CO3) and sodium sulfide (Na2S). Refractometers measure the green liquor's concentration, which helps optimize the causticizing process. This process involves converting sodium carbonate to sodium hydroxide by adding lime (calcium oxide, CaO). Accurate measurement of green liquor concentration ensures the right amount of lime is added, thus optimizing the efficiency of the causticizing process and reducing waste.
• Brown Liquor Control: After the causticizing process, the remaining liquor, called "brown liquor," primarily contains sodium hydroxide (NaOH) and sodium sulfide (Na2S). The concentration of brown liquor is critical for achieving the desired pulp quality and yield. Refractometers help maintain the correct concentration of brown liquor, ensuring consistent pulp quality and minimizing chemical waste.
• Black Liquor Evaporation: Black liquor is concentrated through evaporation to increase its solids content before being burned in the recovery boiler. Process refractometers monitor the concentration of the black liquor, ensuring optimal evaporation rates and preventing potential issues in the recovery boiler.
• White Liquor Quality Control: Refractometers can also be used to monitor the concentration of white liquor, helping maintain the desired alkalinity and sulfide levels, directly affecting the cooking process and pulp quality.
• Recirculation and Monitoring: Process refractometers can be installed at various points in the Kraft pulping process, such as in recirculation lines, to monitor liquor concentrations continuously and adjust process parameters accordingly.

Process refractometers play a crucial role in Kraft pulping by monitoring and controlling the concentrations of green, brown, and black liquors. Their accurate measurements ensure the efficient use of chemicals, minimize waste and help maintain consistent pulp quality.

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Inline Process Refractometers for Tomato Processing

Tomato processors need to anticipate product output, consistency, and quality, as these variables directly impact sales and profitability. However, because of fruit diversity, harvest maturity, and agricultural region, it is challenging to control the consistency and quality of tomato products. 

Consumers frequently choose tomato sauces, pastes, purees, and dressings depending on sweetness levels, so food producers must manage sweetness precisely. Brix is the most commonly used method for assessing sweetness. Degrees Brix (°Bx) is a quick and accurate way to calculate the quantity of sugar in an aqueous solution. 

Refractometry calculates degrees Brix, and refractometers are the devices used to do so. Refractometers, in essence, use a prism to determine how light bends through a substance. The shift in light direction calculates to particulate quantities - in this example, Brix - in a repeatable manner. 

In food processing, there are various types of refractometers. Many food processing labs employ hand-held refractometers for batch sampling. The inline process refractometer is another. It offers Brix measuring control directly on the manufacturing line, and it can be used anytime in the overall process, from the evaporation stages to the concentrated finished product. 

Inline process refractometers are mounted using a sanitary-type pipe adapter designed and produced per 3-A Sanitary Standards. Suppose the tomato product is known to leave persistent coatings on the refractometer prism. In that case, a steam port is added to the adapter, allowing the prism to be steam cleaned at predetermined intervals. 

The refractometer's head is positioned directly in the processing line and provides real-time Brix detection with a measured output. The refractometer's circuitry then conditions the head's signal and compares it to the desired value in a controller. The controller provides a corrective output signal, such as 4-20mA, to a final control device, such as a control valve. The control device increases or reduces the amount of an ingredient. Brix measurement, like any other process control variable (pressure, temperature, level, or flow), is determined and managed by the inline process refractometer via a dedicated control loop, giving the tomato processor better control over product quality and consistency.

For more information on the use of inline process refractometers in tomato processing, contact Electron Machine at +1 352-669-3101 or visit http://electronmachine.com.

Inline Process Refractometers Used in Vaccine and Drug Development

Inline process refractometers are used in drug development and in vaccine manufacturing to ensure safety and efficacy. Their use is integral to the development of virus-based vaccines for diseases such as influenza, MERS, SARS, and COVID-19.

Process refractometers determine the concentration of dissolved solids by making real-time optical measurements of the refractive index (RI) and temperature in a solution. In-process Refractive Index monitoring improves the understanding of process conditions, reduces pharmaceutical development time, increases production capacity, improves product stability and product quality, as well as assisting in regulation compliance. RI measurement and control data supports the pharmaceutical manufacturer's  process validation throughout the drug or vaccine development cycle.

Inline process refractometers with hygienic or sanitary process connections are specially designed for the pharmaceutical industry and are used for the measurement of dissolved components in liquids. Sucrose density in virus purification is one example. Viruses can be banded in density gradients of sucrose, and the purification of viruses is done via sucrose density gradient centrifugation. Measuring the sucrose density with process refractometers allows for safe, accurate and efficient collection, ultimately assisting in speedier vaccine development.

For more information on the use and implementation of inline process refractometers for drug and vaccine development, contact Electron Machine Corporation. Call the in the USA at +1 352-669-3101 of visit their web site at https://electronmachine.com.