Qualitative Analysis of Black Liquor in the Kraft Process

Black liquor is a byproduct of the Kraft process of paper production. The Kraft process, also known as the sulfate process, is a method of pulping wood chips to produce wood pulp, which is then used to make paper. In the Kraft process, wood chips are cooked in a solution of sodium hydroxide (NaOH) and sodium sulfide (Na2S) at high temperatures and pressure. This chemical cooking process breaks down the lignin and cellulose in the wood chips, separating the fibers that can be used to make paper.

During the cooking process, a black, viscous liquid known as black liquor is produced. Black liquor contains lignin, hemicellulose, and other organic compounds that are dissolved or suspended in the cooking liquor. It also contains inorganic chemicals such as sodium hydroxide and sodium sulfide, as well as dissolved minerals from the wood chips.

Black liquor is separated from the wood pulp during the pulp washing and recovery process. It is then burned in a recovery boiler to generate steam and electricity for the mill. The heat from the burning black liquor drives a steam turbine, which generates electricity that can be used to power the mill and any excess can be sold back to the grid. The inorganic chemicals in the black liquor are also recovered and recycled back into the Kraft process.

Process refractometers are used in paper mills to analyze black liquor in order to determine its concentration and solids content. The concentration of black liquor can have a significant impact on the efficiency of the pulping process, so it is important to accurately measure it.

To use a process refractometer to analyze black liquor, a sample of the liquor is typically collected and placed in a sample cell. The refractometer then measures the refractive index of the sample, which is a measure of the way that light is bent as it passes through the sample. The refractive index of the sample is then used to calculate the concentration of the black liquor.

Process refractometers are widely used in paper mills because they are fast, accurate, and easy to use. They can also be used to measure the concentration of other process fluids, such as process water and spent cooking liquor.

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

Applying Refractometers in Starch/Sizing Liquid for Paper Production

Cooked starch or sizing liquid is used in paper sizing to reduce the paper's tendency to absorb liquid when dried. The reduction in fluid allows inks and paints to better remain on the surface and helps create stabilized sizing conditions, allowing a consistent paper quality across the different paper grades.

The MPR E-Scan gives paper companies the ability to accurately control the sizing/cooked starch by detecting changes in the concentration of the cooked starch. This precise measurement effectively controls the freshwater flow to the size press/starch circulation system, reducing excessive water usage. Combining the measurement with data-analysis tools, a company can monitor inefficiencies in the starch/sizing line and evaluate the dilution levels. The result is improvements in starch/sizing operation's efficiency and an overall reduction in water, reducing the overall time needed to meet target dilution. By providing a near-instant reading of starch concentration and temperature, the instrument removes the reliance on offline testing. This application should also include automatic prism wash using heated high-pressure water and matching the wash water temperature to the process, reducing any thermal shock and sensor.

FEATURES

• Data logging output for dilution and temperature
• Multiple product ranges and configurable set points.
• Sapphire Prism
• Daylight visible color display
• NEMA 4X
• Stainless-steel CNC machined sensing head
• 4-20mA & RS-232 outputs
• In-house manufactured in USA
• 24 Hour Service Support
• (2) Input & (6) Configurable output relays
• Configurable alarm points: high/low, setpoint/ deviation, etc. 

The MPR E-Scan is constructed of various alloys to ensure a long service life in a harsh chemical environment. The instruments fit into any process with custom pipeline adapters. Due to the unique measurement principle, the instrument readings are unaffected by bubbles, particles, fibers, color, flow, pressure, or vibration. Paper companies can guarantee that proper dilution was met and maintained by utilizing the instrument to control and monitor the starch liquid concentration.

KEY BENEFITS

• Increased paper quality.
• Continuous accurate control of dilution factor.
• Consistent cooked starch quality.
• Increased paper grade production.
• Reduced water and steam use for the cooking process.
• Error and Warning light indications.
• Reduced time for correct sizing/ starch concentration.
• Continuous temperature readings. 

Electron Machine Corporation
https://electronmachine.com​​
+1 352-669-3101

Green Liquor Process Management with Inline Refractometers

Green liquor is the dissolved concentrations of sodium sulfide, sodium carbonate, and other substances from the paper-making process's recovery boiler. Measuring its density is an essential aspect of paper production quality. 

The Electron Machine MPR EScan is used to measure the green liquor dissolved density, or TTA, at two different points in the process: after the green liquor dissolving tank and after the green liquor clarifier. With the refractometer sensing head positioned directly in the primary process lines, inline measurement enables real-time management of green liquor dilution to meet target TTA set-points. Excessive green liquid density and the accompanying harmful imminent crystallization within the dissolving tank are also indicated (and prevented) by the measurement. 

One considerable challenge is sensor head scaling associated with green liquor. An optical coating forms on the refractometer sensing head. The coating must be dealt with efficiently and quickly to maintain the accuracy and with minimum maintenance. This is key for the refractometer's ability to provide an acceptable measurement cycle and duration. The maintenance necessary to keep the cleaning system running efficiently is challenging. 

Controlling scaling is optimal when the variance of green liquor solids is reduced by automatically adjusting weak-wash dilution with the MPR E-Scan refractometer. Additionally, pressurized water, heated to the process temperature, rinses the refractometer optical components effectively, resulting in a further scaling reduction. The end outcome is advantageous for both control and acceptable maintenance scheduling. 

By limiting thermal changes, minimizing maintenance, and providing a dependable measurement source for automatic inline control, refractometers with accompanying heated high-pressure water cleaning systems deliver excellent results in improving green liquor processing.

Visit www.electronmachine.com or contact 352-669-3101 for more information.

Common Applications for Inline Process Refractometers in Everyday Products

Process refractometers are used in many applications, across a wide variety of industries today. These digital electronic instruments are used to measure dissolved solids and percent concentration in many common, and not-so-common, products. From foods such as juice and jellies, to harsh chemicals such as sodium hydroxide and sulphuric acid, to the paper you touch everyday, there's probably a refractometer monitoring the production line to ensure consistent quality.

Listed below are industries and applications where you may find inline process refractometers.

THE CHEMICAL INDUSTRY

Common chemical processing applications:
Sodium Bicarbonate; Copper Chloride; Hydrogen Peroxide; Acids; Acrylate; Ammonium Hydroxide; Sodium Dichromate; Polymers; Iron Chloride; Sodium Hydroxide; Ammonium Nitrate; Polymers; Lubricating Oils; Chromium Trioxide (Or Chromic Acid); Acetic Acid; Ammonium Fluoride; Oleum; Amine Oxide; Resins; Ethylene Glycol; Polyamides; Nickel Chloride; Ethylene; Glycols; Formic Acid; Amino Acid; Resins; PET; Solvents; Sulphuric Acid; Glycerol; Urea; Formaldehyde; Fluranes; Coolants; Nitric Acid; Polycarbonates; Caustic Soda; Polyethylene; Gels; Cellulose Derivates; Ammonium Sulphate; Citric Acid; Sodium Gluconate; Lactic Acid; Resins; Styrenes.

THE PLASTICS INDUSTRY AND SYNTHETIC FIBER INDUSTRY

Common process applications in the production of plastics and synthetic fiber:
Hexamethylene Diamine; Polycarbonates; Vinyls; Polyethylene; Additives; Dimethylformamide; Fiberglass; Rayon; Cyclohexanol; PET; Polyamides; Cyclohexanon; Nylon Salt; Adipic Acid; Styrenes; Polyesters; Polymers; Dimethylterephthalate; Acetate; Resins; Acrylics.

THE PULP STOCK & PAPER PROCESSING INDUSTRY

Common applications in pulp processing and paper production include:
Chlorine Dioxide; Alum; Oxidized Starch; Sizing Chemicals; Black Liquor; CMC; Green Liquor; Starch; Latex; Ozone; Hydrogen Peroxide; White Liquor; PVA; Styrene Acrylic; Dextrin; Styrene Butadiene Latex; Sodium Dithionite.

DETERGENTS, LOTIONS, AND SOAP PRODUCTION

Common applications in soap and detergent production include:
Palm Oil; Glycerol; Caustic Soda; Salt; Fatty Alcohols; Caustic Potash; Soda Ash; Sodium Bicarbonate; Citrus Oils; Fatty Acids.

THE PRODUCTION AND PROCESSING OF STARCH SWEETENERS

Common applications in the production of starch-based sweetners:
Maltose; Fructose; Aspartame; Sorbitol; Flavors; Lactitol; Xylose; Mannitol; Dextrose; Glucose; HFCS (high fructose corn syrup).

IN SUGAR PROCESSING

Common applications in sugar processing:
Liquid Sugar; Confectionery Sugar; Affination; Extraction; Vacuum Pan; Molasses; Thick Juice; Press Water; Brown Sugar; Molasses; Thin Juice; Invert Sugar; Cane Sugar; Sucrose; Beet Sugar.

For more information about the application of process refractometers in industrial applications, contact Electron Machine Corporation by calling 352-669-3101 or by visiting https://electronmachine.com.

A BLRBAC Compliant Monitoring System Designed Specifically for Black Liquor Recovery Boilers

MDS Monitor Divert System

The Electron Machine Corporation manufactures a BLRBAC compliant Black Liquor solids monitoring system designed specifically for Black Liquor Recovery Boilers.

The Black Liquor Recovery Boiler Advisory Committee is a group that exists for the purpose of generating safety procedures and guidelines that govern the operation of Black Liquor Recovery Boilers.  The BLRBAC was formed in 1961 by several groups of concerned professionals that had become alarmed by the number of Black Liquor Recovery Boiler explosions. 

The MDS Monitor Divert System consists of two completely independent MPR E-Scan Hybrid-Digital refractometers with a separate monitor console that supervises the proper operation of each refractometer. The monitor constantly insures that all parameters remain within operational limits and applies the proper divert or alarm actions should a fault or low solids liquor be detected. A built-in printer records all actions with a date and time stamp. The entire system is designed to be user friendly with large daylight-readable color displays and an intuitive menu-driven interface.

Isolation Valves are also required to meet the BLRBAC guidelines and allow the refractometer sensing heads to be isolated from an active pipeline should maintenance be needed. The system closely monitors the position of these isolation valves to verify that the refractometers are in service.

All functions of the MDS Monitor Divert System are automatic. For example, should a refractometer fault occur the unit is electronically removed from service and an alarm is activated. Simultaneously the output signal is driven low to warn the operator to disregard this reading. The monitor system then isolates, displays the fault and provides a hard copy record on the built-in printer. Liquor diversion is now controlled by the refractometer in service.

• Intelligent purge function- ensures the proper cleaning and extends prism life 
• Divert trending - provides an actual time left before a diversion when liquor solids are declining 
• Password protection- to protect critical software areas

The MDS Monitor Divert System is pre-wired and mounted on a panel for easy installation. All customer connections are made to a single terminal strip. Standard output is a 4-20mA for liquor concentration with relay contacts for liquor divert, alarms, and system error indicators. A remote divert input is also available. The system can be provided in an optional stainless steel enclosure with either a vortex-cooler or fan ventilation depending on the specified mounting location.

For more information on the BLRBAC visit here.

For more information on the MDS Monitor Divert System visit here.

Reliably and Consistently Measuring Green Liquor Density in the Paper Mill

Paper mill green liquor
density measurement system.

Green liquor is the dissolved concentration of sodium sulfide, sodium carbonate, and other compounds from the recovery boiler in the paper making process. Measuring its density is a critical component for the quality of the paper production.

The difficult scaling associated with green liquor results in an optical coating on the refractometer sensing head. If this scaling can be controlled to allow an acceptable duration of on-line measurement, and then effectively removed when coating occurs, the accuracy of the refractometer can be fully utilized with minimal maintenance. The primary issue then becomes the maintenance required to keep the cleaning system operating effectively. 

Using inline refractometers with accompanying heated high-pressure water cleaning systems provides excellent results in effective removal of optical coatings by reducing thermal changes, minimizing maintenance, and allowing for a reliable measurement source for on-line automatic control.

The Electron Machine MPR EScan is used to measure the green liquor dissolved density, or TTA, at two stages in the process: after the green liquor dissolving tank and after the green liquor clarifier. The in-line measurement, with the refractometer sensing head installed directly in the main process lines, allows real-time control of green liquor dilution to meet target TTA set-points. The measurement is also used to indicate (and prevent) excessive green liquor density and the resulting dangerous impending crystallization within the dissolving tank.

Electron Machine MPR Escan

Reducing the variation of green liquor solids by automatically controlling weak-wash dilution with the MPR E-Scan refractometer results in a reduction in scaling. Scaling issues are further reduced when pressurized water, heated to the process temperature, is used to effectively clean the refractometer optical components. The compound result is beneficial for both control and maintenance.

For more information, visit www.electronmachine.com or call 352-669-3101.