Chemical Recovery in Black Liquor Processing for Pulp and Paper Production

Pulp and paper mill.

For economic and environmental reasons, pulp mills employ chemical recovery processes to reclaim spent cooking chemicals from the pulping process. At kraft and soda pulp mills, spent cooking liquor (referred to as weak black liquor), from the brown stock washers is routed to the chemical recovery area.

The chemical recovery process involves concentrating weak black liquor, combusting organic compounds, reducing inorganic compounds, and reconstituting the cooking liquor.

Residual weak black liquor from the pulping process is a dilute solution (approximately 12 to 15 percent solids) of wood lignin, organic materials, oxidized inorganic compounds (Na2SO4, Na2CO3), and white liquor (Na2S and NaOH). The weak black liquor is first directed through a series of multiple-effect evaporators to increase the solids content to about 50 percent to form “strong black liquor.”

Monitoring percent solids in black liquor
is an important part of chemical recovery.

The strong black liquor from the multiple-effect evaporator system is either oxidized in the black liquor oxidation system, or routed directly to a non-direct contact evaporator (also called a concentrator). Oxidation of the black liquor prior to evaporation in a direct contact evaporator reduces emissions of odorous total reduced sulfur compounds. 

The solids content of the black liquor following the final evaporator/ concentrator typically averages 65 to 68 percent. The soda chemical recovery process is similar to the kraft process, except that the soda process does not require black liquor oxidation systems, since it is a non-sulfur process that does not result in total reduced sulfur emissions.

The concentrated black liquor is then sprayed into the recovery furnace, where organic compounds are combusted, and the Na2SO4 is reduced to Na2S. The black liquor burned in the recovery furnace has a high energy content which is recovered as steam for process requirements, such as cooking wood chips, heating and evaporating black liquor, preheating combustion air, and drying the pulp or paper products. 

The process steam from the recovery furnace is often supplemented with fossil fuel-fired and/or wood-fired power boilers. Particulate matter (primarily Na2SO4) exiting the furnace with the hot flue gases is collected in an electrostatic precipitator and added to the black liquor to be fired in the recovery furnace.

Refractometer for black liquor measurement.

The process of chemical recovery must be carefully managed. Process variables such as temperature, pressure, flow and level require robust instruments to ensure safety and accuracy. The measurement of black liquor solids content has relied upon the use of industrial inline refractometers for many decades. The Electron Machine Corporation, with it's ruggedly designed MPR E-Scan,  has established itself as the leader in this process. Incorporating a ruggedly designed sensing head with a 2205 S/S prism holder, sapphire prism, LED light source, and very sturdy electronics, the Electron Machine device delivers on it's claim as the "world's most rugged process refractometer".  Since the refractometer is specifically designed for the very harsh environment of a pulp mill, it promises years of low-maintenance and very reliable operation. 

For more information about inline process refractometers for black liquor processes visit this link or contact Electron Machine at 352-669-3101. 

Inline Refractometers for the Production of Jams and Jellies

Refractometers are used to maintain
standards of jams and jellies.

The quality and uniformity of a food product is paramount to the sales of that product. Assuring that standards are maintained is key to quality and consistency.  Jams, jellies, marmalades, conserves and fruit butters are characterized by concentration of fruit components and sugars. Attention to solids content, pH, and sweetness is essential, and controlling these variables in a production environment requires the proper systems, instruments, and automation.

Jams, jellies, marmalades, conserves and fruit butters are made by boiling fruit and sugar together to give a high solids product, and are characterized by concentration of their fruit components and sugars.

Inline refractometer for jam and jelly production.

Accordingly, standards of identity have been enacted to require specific amounts of the comparatively expensive fruit ingredient. Without these guides, producers could substitute flavored and colored pectin and sugars in place of real fruit.

Definitions:

• Jam – a product containing both soluble and insoluble fruit constituents.
• Conserve or preserve – large pieces of fruit are present.
• Butter - a smooth, semisolid fruit mixture with no fruit pieces or peel. May be spiced
• Marmalade – are made from citrus fruits and contain some peel.
• Jelly – is made from filtered fruit juice, no pieces of fruit or insoluble solids present.

In the U.S. jams and jelly products are graded as follows:

• Fancy  - 50 parts fruit to 50 parts sugar 
• Standard  - 45 parts fruit to 55 parts sugar 
• Imitation - 35 parts fruit to 65 parts sugar
• Fruit butters - At least 5 parts fruit to 2 parts sugar

Standards of identity can be easily formulated with the aid of a refractometer - and instrument that the sugar/solids content by the angle that the solution refracts or bends light. Refractometers are the preferred method of determining of measuring soluble solids and sugars in many food products.

In large scale commercial food production environments, inline process refractometers provide real-time sugar and solids measurement allowing plant operators tight control of product variables so that product uniformity and quality is maintained.

DCR E-Scan Hybrid-Digital Refractometer

The DCR E-Scan is a hybrid-digital critical angle refractometer. It is used to measure the refractive index of process fluids and may be used as an integral part of a complete process control system.

With an extremely durable Sapphire prism as the foundation, the hybrid-digital design provides digital accuracy with rugged components in the sensing head. This combination produces the essential dependability required for years of use when installed in harsh industrial environments.

The DCR E-Scan is the cost-effective refractometer for an accurate and dependable reading. Electron Machine Corporation calibrates each DCR E-Scan specifically for the intended application. The digital display coupled with the 4-20mA output provides the complete control desired at an affordable cost without sacrificing the rugged reliability desired for today's industrial applications.

DCR E-Scan Digital Hybrid Refractometer from Electron Machine Corporation

Don't Forget Customer Support and Technical Support When Buying Process Instruments

Make sure your vendor's Customer Service and Tech Support
are knowledgeable, experienced, and ENTHUSIASTIC.

Today, many engineers do their product selection largely via the Internet, and usually by just comparing specifications between manufacturers. While this provides a fast, efficient, and objective means to narrow down prospective vendors, it totally ignores a critically important (albeit subjective) component to the success of their project - the vendor's Customer and Technical Support infrastructure.

When choosing a vendor for process instrumentation (industrial refractometers for instance), it's imperative to include an evaluation of the vendor's Technical Support and Customer Support infrastructure. Realizing what these professionals have to contribute, and taking advantage of their knowledge and talent, will save time and money, and greatly contribute to a successful project outcome.

Understanding Why Technical Support and Customer Support are Critical

It's all about two things:

1. Experience
2. Attitude

Experience

"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." Red Adair

By the nature of their job, Customer Service personnel are current on new products, their capabilities and their proper application. Unlike anecdotal information available on the Web, support personnel have first hand knowledge and hands-on experience. They've seen successful (and unsuccessful) product implementation scenarios and are eager to share. A brief discussion about your application with a specialist will guide you toward selecting the best equipment for the requirement. Also, because they are exposed to so many different applications and situations, Customer/Tech Support personnel are a wealth of ancillary application knowledge.

As a project engineer, you may be treading on fresh ground regarding some aspects of fully understanding the project you're working on. You may not have a full grasp on how to handle a particular challenge presented by the application. Calling upon a source with past exposure and experience to your current application prior to product selection will provide a very real, and very valuable benefit.

Attitude:

"Customer service is not a department, it’s everyone’s job." Anonymous

Choose a company that places a huge emphasis on customer service and do some due-diligence. Determine if they're merely providing lip service, or if extreme customer service oozes from the company pores. 

Sam Walton, the founder of Walmart once said "The goal as a company is to have customer service that is not just the best, but legendary." Make sure the vendor you're evaluating sees things the same way.  While reviews or testimonials (if there are any) can be helpful, they should be viewed judiciously. You're going to have to talk to people and get your own "gut-feel".  Do the employee's seem upbeat and happy? Are they knowledgeable? If they can't answer a question, do they volunteer to connect you with someone who can?  Are they enthusiastic?

As an engineer who designs or manufactures a product or process, it's strongly recommended you make the effort to research, contact, and get a first-hand feel for your prospective vendor's Customer and Technical Support Team. Learn about their product and application knowledge, their experience and their commitment to excellence. Taking the time to do this will raise the likelihood that your project will come in on time, on budget and shine brightly upon you.

Refractometers for Food and Beverage Processing

Refractometers commonly used to detect sugar levels and properties of jams juices, beverages, dairy products and much more.

Electron Machine Corporation developed the first in-line process refractometer more than 50 years ago when orange juice was first concentrated. Since that time, their refractometers have been successfully applied on many more applications including the production of sucrose, fructose, dextrose, soft drinks, fruit juices, dairy, apple sauce, jams, jellies, beer, wine, coffee, tea, vegetable oils, tomato paste, ice cream and honey.

With an extremely durable Sapphire prism as its foundation, the Electron Machine MPR E-Scan combines accurate measurements with ruggedized components in the sensing head combining for years of of dependable and accurate service in harsh food production environments.

Industrial Refractive Index Transmitters

Example flow loop diagram
showing role of transmitter.

Transmitters are process control field devices. They receive input from a connected process sensor, then convert the sensor signal to an output signal using a transmission protocol. The output signal is passed to a monitoring, control, or decision device for use in documenting, regulating, or monitoring a process or operation.

Transmitters are available for almost every measured parameter in process control, and often referred to according to the process condition which they measure.

The refractive index determines how much light is bent, or refracted, when entering a material. When light moves from one medium to another, it changes direction (refracted). This change in the direction of the light can be measured and applied to properties of the material.

Example of Industrial Refractive Indextransmitter/controller.
Can act as transmitter alone, or with
optional PID control functions.

Industrial Refractive Index transmitters directly measure the refractive index of process fluids. It then conditions the input signal, making it linear, and then converts that signal into any number of customer-desired units (Brix, Percent Solids, Dissolved Solids, SGU, R.I., etc.) and transmits a standard, linear electrical output (4 to 20 mA) that can be utilized by receiving instruments and displays.

Many transmitters are provided with higher order functions in addition to merely converting an input signal to an output signal. On board displays, keypads, Bluetooth connectivity, and a host of industry standard communication protocols can also be had as an integral part of many process transmitters. Other functions that provide alarm or safety action are more frequently part of the transmitter package, as well.

Industrial Refractive Index transmitters have evolved from simple signal conversion devices to higher functioning, efficient, easy to apply and maintain instruments utilized for providing input to process control systems.

For more information on Industrial Refractive Index transmitters visit Electron Machine at http://www.electronmachine.com or call 352-669-3101.

Industrial Inline Refractometer for Green Liquor Density in Pulp & Paper Plant

Electron Machine Corporation has been actively refining the use of refractometers for measuring green liquor density for over 30 years. Their incremental efforts in this application has led to the current combination using the MPR E-Scan with their high pressure cleaner (HPC) adapter supplied with heated demineralized water. The removable nozzle provides for easy maintenance. This system ensures an accurate measurement in these difficult scaling conditions.

Industrial Inline Refractometer for Green Liquor Density in Pulp & Paper Plant from Electron Machine Corporation

New Electron Machine Marketing Video

Here is a new Electron Machine marketing video. Thanks to our loyal customers around the world for your support and business. Electron Machine continues to develop innovative products that apply the refractive index for greater efficiency and safety in industrial production.

The World's Most Rugged Inline Process Refractometers

Electron Machine manufactures the world's most rugged industrial, in-line refractometers used in pulp & paper processing, chemical production, and food and beverage processing.

The company is renowned for manufacturing industrial inline refractometers that hold up to the rigorous environments and the steady demands in these applications. These refractometers are built to withstand the most harsh conditions while delivering reliable and consistent readings and providing safe, reliable, and accurate process measurement and control.

Electron Machine inline refractometers are used in numerous applications in the paper industry such as black liquor, and green liquor sensing; in the food industry to detect sugar levels and properties of jams juices, beverages, and dairy product; and in the chemical industry to measure the strength of a chemical when diluted with water or another chemical.

For more information, visit http://www.electronmachine.com.

MPR- E-Scan Inline Refractometer Settings and Readings Overview

The MPR E-Scan is an in-line process refractometer that directly measures the refractive index of process fluids and then displays the reading in any number of customer-desired units (Brix, Percent Solids, Dissolved Solids, SGU, R.I., etc.). A simple 0-10Vdc signal is used to transmit the reading from the sensing head to the electronics console, ensuring a robust reading that has a minimal chance of being effected by interference. The entire package is NEMA 4X rated and designed and manufactured with the best materials for each application to provide years of trouble-free service with a minimum amount of maintenance.

The video below provides and overview of zeroing, setting, and reading the refractometer.

Replace the Sensing Head on MPR E-Scan and MDS-Divert Systems

The MPR E-Scan is a rugged, industrialized, in-line process refractometer. It directly measures the refractive index of process fluids and then displays the reading in any number of customer-desired units (Brix, Percent Solids, Dissolved Solids, SGU, R.I., etc.).

The MDS Monitor Divert System is a BLRBAC compliant Black Liquor solids monitoring system designed specifically for Black Liquor recovery boilers.

The following paper illustrates the correct way to replace the sensing head on MPR E-Scan and MDS-Divert Systems from Electron Machine Corporation.

Electron Machine Refractometer Sensing Head Replacement from Electron Machine Corporation

Inline Refractometers for Measuring Black Liquor Evaporation

Measuirng black liquor solids concentration.

Introduction:

Refractometers have long proven to be the instrument of choice for black liquor solids concentration. Electron Machine Corporation of Umatilla, Florida pioneered this technology to accurately measure black liquor dissolved solids 5 decades ago. Their MPR E-Scan inline refractometer provides digital accuracy with rugged components required for years of reliable use when installed in harsh industrial environments. This combination allows for easy integration into a mill-wide monitor / control system providing operators the information needed for efficient and easy-to-service control.

Application:

An important and overlooked area for refractometers is the pulp washing operation. By monitoring the concentration output the washers can be balanced to meet the needs of the evaporation process and a mill is able to regulate the mixing liquor. This control allows a consistent concentration supply to the evaporators and boiler. This installation is simple and greatly reduces hand sampling.

MPR E-Scan

Evaporation:

By installing the Electron Machine Corporation MPR E-Scan with Isolation Valve Adapters before and after each evaporator effect, the concentration and temperature output can be utilized to monitor efficiency, detect problems and operate economically. This monitoring allows control operators to adjust steam usage for optimal solids evaporation. Operators can determine if a quick flush cleaning can be performed to improve efficiency, prolonging the time between invasive, labor intensive cleanings. It also allows the detection of any problems before the liquor reaches the boiler, plus provides a consistent solids percentage for firing.

Conclusion:

With the addition of the Electron Machine Corporation MPR E-Scan to a mills process control system, a company can see increased profitability through the optimized control of steam usage, reduced labor cost from the reduction of offline hand sampling and the ability to prolong the time between labor intensive offline cleanings. This greater control provides more consistent firing solids allowing boilers to operator more efficiently.

Key Benefits:

• Consistent black liquor solids
• Minimize steam consumption
• Economical operation
• Optimize man hours
• Reduce costly evaporator cleanings

Electron Machine Maintains "A" Rating with ISNetworld

Electron Machine Maintains
ISNetworld A Rating

ISNetworld is a resource that assists in establishing partnerships between hiring clients and contractors through corporate transparency across management, training, and safety infrastructure. They maintain a world-wide online contractor management database, designed to meet internal and governmental record keeping and compliance requirements. They collect and present health and safety, procurement, quality and regulatory information to their subscriber-ship of hiring clients.

ISNetwork’s goal is to connect hiring clients with safe, reliable and sustainable contractors and suppliers. Their process (for contractors) requires maintaining accurate information, records, and processes concerning insurability, safety, training, hiring, and diversity information. ISNetwork's hiring clients and contractors both benefit through a streamlined, thorough, and consistent qualification process.

Electron Machine Corporation is proud to be an ISNetwork approved contractor in good standing and has has been awarded an “A” in contractor rating for demonstrating high standards of quality and safety. An “A” rating typically means the contractor is listed as “excellent/preferred” and can be hired without restriction.

Refractometer for Juice Concentration Processing

In-line process refractometer

The production of fruit juice concentrate involves taking a comparatively dilute feed stock of fruit juice and delivering a uniformly concentrated output. The process accomplishes removal of water through an evaporative operation employing purpose specific equipment. Fruit juice concentrate contains the solid components of the feedstock fruit juice, and provides for easier transportation and longer storage life.

The array of fruits processed into concentrate includes almost every commercially harvested type.

Juice is extracted from various fruits in a number of ways that are specifically adapted for the shape, size, and nature of the fruit. Once the juice is extracted and purified it will generally be stored in a primary tank which serves as the feed device to the evaporator. Juice concentration will vary at this initial stage due to a number of natural factors. The concentration process output will provide product uniformity.

Regardless of the method used for concentrating the juice, in-line process refractometers can be used at strategic points in the process to measure solids concentration and evaluate equipment performance and product quality. Output signals from the refractometers serve as inputs to the command and control system for the evaporators, allowing feed rate to closely match evaporation rate and make most efficient use of the energy consuming equipment. 

In an industrial environment, ruggedness, reliability, and accuracy are key features needed for an in-line process refractometer. Share your refractometry challenges with the experts at Electron Machine Corporation and get effective solutions.