Showing posts with label in-line process refractometer. Show all posts
Showing posts with label in-line process refractometer. Show all posts

Shedding Light on Quality: The Role of Process Refractometers in Tomato Processing

Shedding Light on Quality: The Role of Process Refractometers in Tomato Processing

Refractometers have carved out a significant niche in various industries, but their role in the food sector, particularly with tomato products, stands out as noteworthy. Let's look into the application of process refractometers to ensure tomato-based products' quality, consistency, and safety.

What is a Process Refractometer?


At its core, a refractometer is a device that measures the extent to which light is bent (or refracted) when it passes through a substance. This refraction is directly related to the concentration of solutes in a solution. In the food industry, process refractometers gauge the concentration of sugars, salts, and other soluble substances in food products in real time, making them invaluable in maintaining product consistency.

Importance in Tomato Products


The quality of tomato products is often gauged by their consistency and the concentration of soluble solids, primarily sugars and acids. Given that tomatoes can vary in sugar content based on their variety, maturity, and growing conditions, ensuring consistency in commercial products is challenging. Here's where process refractometers come into play:
  1. Brix Measurement: Brix is a scale that indicates the sugar content of an aqueous solution. One degree Brix corresponds to 1 gram of sucrose in 100 grams of solution. In the tomato industry, the Brix measurement helps determine the sugar concentration in tomato products like sauces, ketchup, and pastes. A consistent Brix level ensures a uniform taste across batches.
  2. Ensuring Quality: Besides flavor, the concentration of soluble solids in tomato products affects texture and viscosity. By constantly monitoring this concentration, manufacturers can make real-time adjustments to the processing parameters, ensuring the end product maintains the desired quality.
  3. Economic Considerations: Overconcentration means more tomato content than necessary, which can waste resources, while underconcentration might not meet industry standards or consumer expectations. By maintaining the right concentration, manufacturers can optimize costs.
  4. Safety Concerns: Water activity in a product can influence its susceptibility to microbial growth. By monitoring and controlling the concentration of solutes, manufacturers can enhance tomato products' safety and shelf life.

Practical Applications


  • Tomato Paste Production: Refractometers ensure that the concentration process yields a consistent product for direct consumption or as a base for other tomato-based products.
  • Ketchup & Sauces: Beyond tomatoes, these products often contain additional ingredients like spices, sugars, and vinegar. Monitoring the overall concentration ensures a balanced product that meets the desired flavor profile and texture.
  • Canned Tomatoes: While these are processed less than paste or ketchup, providing the brine or juice's concentration can affect the product's overall taste and shelf life.
  • Juice Production: Whether it's pure tomato juice or a blend, maintaining the right Brix level is essential for consistent flavor and quality.

The importance of process refractometers in the food industry, especially in producing tomato products, cannot be overstated. They play a pivotal role in maintaining product quality, safety, and consistency, ensuring that consumers receive the same great taste and texture with every purchase. As technology advances and the demand for consistent, high-quality food products increases, the reliance on such tools will only grow.

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

Inline Process Refractometers for Pulp & Paper Mill Applications


Approximately 50 years ago, the Electron Machine Corporation became the first company to employ refractometers to precisely quantify the dissolved particles in black liquor. Our extensive experience with this application has resulted in several design characteristics specifically tailored to process measurement challenges in this demanding environment. For decades, the paper industry has also relied on Electron Machine refractometers to correctly measure green liquor solids in pulp and paper manufacturing.

Electron Machine
352-669-3101

Successful, Long-term EMC and Florida Food Products Partnership Maintains Consistent, High Quality Production


Florida Food Products, innovator and leader in clean-label, natural food processing, and Electron Machine; a winning team.


Electron Machine Corporation and Florida Food Products have had a long and successful relationship with each other. In fact, Florida Food Products was one of the first food companies Electron Machine Corporation ever placed a rugged, in-line, process refractometer into operation; the year was 1956.
in-line process refractometer
Located just a few miles from each other, the relationship was a natural.  Recently, Florida Food Products underwent a large expansion, requiring additional instrumentation from Electron Machine Corporation.  The first of these new generation in-line process refractometers was installed this past summer, and immediately paid dividends.  Upon installation concerning a test batch, the process refractometer read the material at a lower percentage of BRIX than anticipated by the engineers starting the line.  The staff at Florida Food Products made the appropriate changes to the concentration and the refractometer was deemed a great success.  Since this time, another unit has been purchased by the Florida Foods Team.

Electron Machine Corporation salutes the long relationship we have had with the Florida Food Products Team and looks forward to servicing this valued client for many years to come.

For more information, contact Electron Machine Corporation. Call them at 352-669-3101 or visit them at https://electronmachine.com.

Measuring Solids in Pulp & Paper Black Liquor

Pulp and paper plant
Pulp and paper plant.
Industrial paper manufacture involves a procedure known as the Kraft process, where wood is converted into wood pulp and then into paper. The process, however, produces a toxic byproduct referred to as black liquor. This primarily liquid mixture of pulping residues (such as lignin and hemicellulose) and inorganic chemicals from the Kraft process (such as sodium hydroxide and sodium sulfide) is toxic.

Until the invention of recovery boilers in the early 20th century, black liquor was often simply released into waterways. Black liquor recovery boilers allowed paper manufacturers to recover and reuse the inorganic chemicals and extract energy from the pulping residues.

Paper processingReliable, continuous measurement of black liquor solids content is a subject of considerable importance to the pulp industry. The solids content of liquor introduced into a recovery furnace can have a pronounced influence on firing behavior. Current trends toward better control of the recovery furnace for reasons of safety and reduced air emissions require a greater degree of control over incoming solids content and appropriate adjustment of operating conditions to handle variations in solids content. This, in turn, requires a reliable method for continuously monitoring solids content.

Instruments such as inline process refractometers successfully measuring black liquor solids concentration continuously. These instruments have the dependability, accuracy, and reliability to augment safe operation of recovery boilers. Refractive index-type instruments are more widely accepted and far more successful with less maintenance requirements than other types of instruments used for black liquor solids measurement, and have proven reliable and accurate for automatic monitoring of black liquor solids concentration.

Inline Process Refractometers for Fruit Juice Concentrate Production

Fruit Juice Concentrate
Just about every fruit harvested is processed to a concentrate. Fruit juice concentrate provides for easier transportation and longer storage life for both producers and consumers. Production technology for the juice concentration has become quite advanced, resulting in improved quality and consistency. Sweetness, color and solid components from the feedstock fruit juice carefully monitored and controlled.

Fruit juice concentrate production starts with dilute juice feedstock, the application of carefully controlled heat to evaporate off water, ultimately resulting in a uniform and consistent concentrated juice. The fruit juice stock is extracted from various fruits in a number of ways that are specifically adapted for the shape, size, and nature of the fruit. It is then purified and stored in primary holding tanks. Juice concentration will vary at this initial stage due to a number of natural factors and needs to be processed to desired quality standards.

One objective of the concentration process is to remove excess water in a consistent and uniform manner. Excess water removal is done through the use of specialized multi-stage evaporators that extract water without damaging the juice by applying improper amounts of heat. A closed-loop control system monitors a variety of process variables such as temperature, flow, and pressure from multiple process sensors. The readings from these sensors drive proportional outputs that modulate final control elements such as control valves.

Process refractometers are sensors used at strategic points to measure dissolved solids (sugar) concentration.  By monitoring and controlling percent solids and Brix, plant operators gain tighter control of product quality and more efficient use of equipment (possible energy savings).

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

Video: Applying Refractometers to the On-line Measurement of Green Liquor Density

A presentation to the Western Canada Black Liquor Recovery Boiler Advisory Committee (BLRBAC) by Electron Machine Corporation. The presentation slides were made in to this video for viewing on YouTube.

Process Refractometers for Food and Pharmaceutical Processing

Process Refractometer
Process refractometers provide the analysis to quickly, reliably, and very accurately identify a sample and determine it's concentration and purity levels. They measure the refractive index and temperature of flowing liquids, and apply mathematical functions to determine the concentration of dissolved solids.

Process refractometers are particularly useful in the food and pharmaceutical industries where they are used to optimize production processes, control quality, and ensure consistency and purity.

In commercial food applications such as juice production or tomato processing, refractometers are used to measure degrees Brix. The Brix scale relates refractive index to sugar concentration, and is a key way to maintain consistency. For example, process refractometers are used for the concentration process of fruit juices. The concentration process is normally achieved by removing water through evaporation, and by measuring Brix, the evaporation process can be controlled and related to the desired juice concentration.

In the pharmaceutical industry, process refractometers are used to monitor and control concentration levels during supersaturation, a critical process in crystallization.  Crystallization is key to the purification of solids in pharmaceutical production.  A high degree of measurement accuracy and reliability provided by the process refractometer ensures precise monitoring and control and a pure product.

There are many other industrial applications for process refractometers, almost all sharing the need for accurate solids content measurement.

For more information about process refractometers, contact Electron Machine. Visit them at https://electronmachine.com or call 352-669-3101.

In-Line Process Refractometers

In-line Process refractometer
In-line Process refractometer sensor in spool-piece.
In-line Process refractometers are used to continuously monitor the concentrations of liquids used in pulp and paper processing, food processing, the beverage industry, chemical processing, the power industry, and primary metal processing. They monitor, report, and control process variables such as Degrees Brix, Percent Solids, Dissolved Solids, SGU, R.I. and deliver an output to external devices such as controllers, recorders, indicators, and PLC's.

In-line Process refractometers save labor costs, streamline the manufacturing process, and improve quality by detecting inconsistencies in a product early in the production phase.

Process refractometer sensor
Process refractometer sensor.
Process refractometers typically consist of two main components – the sensor, which is inserted to a pipe and is exposed the the product for direct measurement. The sensor is connected by a cable to the second main component, the control module which houses the display, electronics, power supply and output connections. Both the sensor and the control module are designed for high accuracy and precise control. Their housing and cabling are often specialized for use in varying extreme conditions and very demanding environments.

The control module includes programming for a wide variety of commonly required features, capabilities, and options that can be adapted to a customer’s requirements. This microprocessor control also allows for custom programming for specialized needs.
Process refractometer control module
Process refractometer
control module.

The sensor can be supplied with a multitude of mounting and cleaning options. Cleaning options include hand cleaning systems, high pressure cleaning systems, and steam cleaning systems. Mounting adapter options include lined adapters, spool-piece adapters, sanitary connection adapters, and weld-in adapters.

Not to be confused with their distant relatives - the handheld digital or analog laboratory refractometer - today's rugged, industrial in-line process refractometers provides continuous process management for large-scale facilities giving them the ability to increase product yield, maintain consistency, and eliminate waste.

Black Liquor Recovery Boilers

Recovery Boiler
Recovery Boiler (courtesy of Wikipedia)
Article courtesy of Electron Machine Corporation

“Black liquor” is a term used for the waste products that result from the pulping process. The black liquor recovery boiler (BLRB) allows for the chemicals in the waste products to be reclaimed via combustion. These reclaimed chemicals are then utilized to both meet steam demands in the process and to generate electricity.

Modern day BLRBs are designed similarly to industrial boilers, typically as two drum designs, for operating pressure under 900 psi, or single drum designs, for operating pressure over 900 psi. The combustion gases utilized by the boilers can be sticky, so the BLRB furnaces are taller than their utility or industrial watertube counterparts. The amount of pulp producible by a particular mill directly correlates to the size of the BLRB. Small BLRBs process about 750,000 pounds of dry solids per day, and larger BLRBs process about six million pounds of dry solids per day. Precise attention and vigilant maintenance are required in order to maximize investment return for each particular boiler.

Black Liquor
Black Liquor
In order to ensure stabilization of combustion, BLRBs are equipped with auxiliary burners which raise boiler temperature for the combustion process. The firing of the black liquor will eventually become self-sufficient. Combusting the black liquor allows for sulfur compounds used in the pulping process to be reduced to sulfide while inorganic chemicals essential to the process are melted down for reuse. The furnace vaporizes the black liquor as the liquor is sprayed into the furnace. Extra water is vaporized, and some of the combustion takes place as the black liquor falls to the furnace’s floor. The resulting molten smelt flows through spouts, which are operantly cooled via water, to a smelt dissolving tank.

A particular risk of the BLRB process stems from the relationship between molten smelt and water. The pool of molten smelt that accumulates as a result of the reclamation process needs to be kept separate from water, because water and molten material mixing at high temperatures can result in a smelt-water explosion. These explosions can occur when black liquor water content is greater than 42% of the mixture. Additionally, there are numerous ways water can enter the process – as condensation from the soot blower, a faulty steam coil heater, wash hoses – so controller vigilance is absolutely key to explosion prevention.

The Black Liquor Recovery Board Advisory Committee has recently introduced an emergency shutdown procedure, where an emergency evacuation alarm signals as soon as suspected water enters the BLRB furnace. The operator, with corresponding training, shuts down all fuel flow and minimizes combustion until all but a minimal amount of water is drained rom the BLRB. Annual inspections of BLRBs mandate the testing of all pressure parts and safety systems, because utmost care must be assured in preventing risk of system damage or operator harm when dealing with BLRB processes.

Literature Updates for Electron Machine

Electron Machine Corporation recently updated some of their product, application, and support literature. The new pieces are described and linked below:

Operating and Service Manual for MPR E-Scan
Service manual for the MPR E-Scan, a hybrid-digital critical angle in-line process refractometer. It is used to measure the refractive index of process fluids.

MDS (Monitor Divert System) Color Manual
Service manual for the Monitor Divert System, a BLRBAC (Black Liquor Recovery Boiler Advisory Committee) compliant Black Liquor solids monitoring system designed specifically for Black Liquor recovery boilers.

Brochure for refractometers used to detect sugar levels and properties of jams juices, beverages, dairy products and much more.
Brochure for the MPR E-Scan used for measuring the strength of a chemical when diluted with water or with another chemical.
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.).

Quality and Process Optimization with Inline Refractometers

Process refractometer in plant
Process refractometer
in plant.
Process refractometer
Process refractometer
(Electron Machine Corp.)
Refractometry is a technology used to quickly, reliably, and very accurately identify a sample and determine the concentration and purity levels. This is done be taking a sample and measuring the refractive index and temperature of the media.

Process refractometers are used for monitoring and controlling process variables in the flowing process media (liquid) . These instruments are used for continual, extremely accurate, real-time substance identification. Through identifying critical factors such as the concentration and purity, manufacturer's can gain tight control over quality can consistency of product. Applications for process refractometers are found in commercial food & beverage, chemical, pulp & paper, and pharmaceutical industries. All share similar processes lines where process refractometry provides real-time, high value information about the product at critical points. These shared processes are:
process refractometers food and beverage
Process refractometers are used
for food and beverage production.

Concentration
The measurement of concentrations in compounds of organic chemicals, inorganic chemicals, and total dissolve solids are often required for product consistency. Process refractometers can be calibrated to detect a wide range of dilute chemicals and dissolved solids and be an excellent feedback mechanism for these process variables.


Mixing 
Using process refractometers for ingredient mixing to control product quality and production reduces errors and limits variance. Comparing the process media to known reference values, through the use of an inline refractometer, optimizes consistency and maintains quality.


Crystallization
process refractometers in pulp and paper
Process refractometers are critical
for making pulp and paper.
Crystallization plays a key role in purification in many chemical processes, ranging from pharmaceutical manufacturing to food processing to liquor processing in pulp & paper production.  Keeping track of concentration levels is essential for the crystallization process and process refractometers provide real time information that allow process optimization.



Cleaning
process refractometers in chemical production
Process refractometers
have many uses in
chemical production.
Changing product runs through existing lines is a major problem area for quality control. If a process line is used in the production of more than one product, it is important to ensure that no cross-product contamination occurs. To virtually eliminate this concern, process refractometers are used to check in for residual product presence (in real-time), providing assurance that purity levels are their highest.

For more information on industrial process refractometers, contact Electron Machine by visiting https://www.electronmachine.com or call 352-669-3101.

Inline Refractometers Used in Beet Sugar Processing

Beet Sugar Processing
Beets are harvested late in the year and transported by truck to the beet sugar processing facility. The initial process involves washing (beets are dirty), and separation from leaves, stones and other miscellaneous debris. After cleaning, the beets are cut in to thin slices making juice extraction easier.

Juice extraction is done in an agitated hot water diffuser tank that continuously agitates the dilution until the concentration reaches the level that qualifies as juice. Other components and impurities from the beet flesh and skins are also dissolved in the juice which later have to be removed.

Beet Sugar ProcessingThe raw juice is then put through a process call "Carbonatation" that introduces a calcium hydroxide suspension and carbon dioxide under controlled conditions of pH and temperature. This process coagulates impurities and decolorizes the raw juice. The impurities are separated from the clear liquor and calcium carbonate by pressure filtration. The clear liquor is then sent to a multi-stage evaporator to remove water and create syrup.

The syrup is then placed in large boiling pans which boils off remaining water and initiates sugar crystallization. The crystals are then spun to separate them from any remaining mother liquor.

Electron Machine MPR E-Scan
Electron Machine MPR E-Scan
To achieve high quality liquid and crystal sugars, improve efficiency and keep production cost in check, refractometers are employed to deliver accurate in-line Brix and other dissolved solids measurements in the beet sugar refining, evaporation and boiling processes.

In beet sugar refineries, the Electron Machine MPR E-Scan can be used to monitor and control Brix measurement from the beginning of the evaporation stages up to the seed point of crystallization.

Visit Electron Machine at https://www.electronmachine.com or call 352-669-3101.

Understanding Error in Process Measurement

Instrumentation calibration is a procedure through which three general types of errors can be encountered. A typical signifier for a need of instrument recalibration is if the instrument is performing in an incorrect manner. This situation serves as a good way to showcase different types of error related to error analysis.

The three major category of errors regarding measurement are gross errors, systematic errors, and random errors. The first two categories of error, gross and systematic, are related to the two main elements of process control: controller and instrument. Gross errors are a product of the process controller or operator incorrectly evaluating the instrument value, with the best prevention of gross error being careful review of data both while recording and interpreting it.

Systematic errors impact every reading from a particular instrument, and are typically cause for instrument recalibration. Zero errors, where the instrument does not return to the predetermined zero value after each reading, are systematic errors because the same error in measurement is being displayed each time. Lastly, random errors impact instrumentation readings due to causes which are either unknown or simply unpredictable, meaning the error is both not able to be duplicated and is not a result of gross error. Random errors can be challenging to deduce due to both their singularity and their potential lack of a clear cause.

The previously mentioned zero error, also known as a zero shift calibration error, is typified by the resulting readings being offset at the same percentage. For example, a pressure transmitter which is functioning incorrectly as the result of a zeroing error can be corrected by a corresponding zero adjustment. After the adjustment and the transmitter being calibrated back to the correct zero point, the error will disappear. Another common type of systematic error is span shift calibration error. Unlike the zero error, span error can impact readings from the instrument repeatedly, but not necessarily identically. Similarly, by correcting the corresponding setting on the transmitter, in this case the span adjustment, the instrument can be correctly programmed once again by measuring the readings against a properly configured reference.

Hysteresis error occurs when the instrument in question returns erroneous responses as the input variable changes. The antidote to this kind of systematic error is to check the instrument against a pre-defined set of calibration points, first by increasing the input, and then subsequently decreasing the input in sequence to determine how the instrument responds as the input changes. Mechanical friction has been known to be a common culprit for hysteresis errors.

Understanding the capabilities and limitations of whatever instrument is relied upon for delivering process information is essential to successful operation.

Sulfite Pulping

Pulping is the term used for the process which separates wood fibers. Chemical pulping, dissolving the lignin in the wood to create a pulp, is the most commonly used pulping process. Chemical pulping creates higher sheet strength than mechanical pulping; however, yields 40 to 50 percent pulp, where mechanical pulping yields 95 percent pulp.

The two main types of chemical pulping are the more common sulfate pulping (most commonly known as Kraft pulping) and sulfite pulping. Kraft pulping accommodates a variety of tree species, recovers and reuses all pulping chemicals, and creates a paper with a higher sheet strength. Sulfite pulp, however, is easier to bleach, yields more bleached pulp, and is easier to refine for papermaking. The major difference between the two types of chemical pulping is the types of chemicals used to dissolve the lignin.

Sulfite Pulping

The concept of sulfite pulping was created in the United States in 1867, however it was not used in a mill until 1874 by a Swedish chemist who was probably unaware of the U.S. Patent (MacDonald, 277). Sulfite pulping produces a lighter pulp than Kraft pulping. It can be used for newsprint, and when bleached can be used for writing papers and for the manufacture of viscose rayon, acetate filaments and films, and cellophane.

Description of Process 

Sulfite pulping follows many of the same steps as Kraft pulping. The major difference in sulfite pulping is that the digester “cooks” with a mixture of H2SO3 (sulfurous acid) and HSO3 ion in the form of calcium, magnesium, sodium, or ammonium bisulfate). The pulp continues on through the same processes as in the Kraft pulping process.

However, the chemicals separated from the pulp in the washers may or may not go into a recovery process. Chemical recovery in sulfite pulping is practiced only if it is economical. If chemical recovery does occur the liquor goes through an evaporator and then to a recovery furnace. Here, smelt is not formed, but ash and SO2 are formed.

Abstracted from Washington State
Air Toxic Sources and Emission
Estimation Methods

Overview of Chemical Recovery Processes in Pulp & Paper Mills

Chemical Recovery Processes in Pulp & Paper Mills
Figure 1
The kraft process is the dominant pulping process in the United States, accounting for approximately 85 percent of all domestic pulp production. The soda pulping process is similar to the kraft process, except that soda pulping is a non-sulfur process. One reason why the kraft process dominates the paper industry is because of the ability of the kraft chemical recovery process to recover approximately 95 percent of the pulping chemicals and at the same time produce energy in the form of steam. Other reasons for the dominance of the kraft process include its ability to handle a wide variety of wood species and the superior strength of its pulp.

The production of kraft and soda paper products from wood can be divided into three process areas:
  1. Pulping of wood chips
  2. Chemical recovery
  3. Product forming (includes bleaching)
Chemical Recovery Processes in Pulp & Paper Mills
Figure 2
The relationship of the chemical recovery cycle to the pulping and product forming processes is shown in Figure 1. Process flow diagrams of the chemical recovery area at kraft and soda pulp mills are shown in Figures 1 and 2, respectively.

The purpose of the chemical recovery cycle is to recover cooking liquor chemicals from spent
cooking liquor. The process involves concentrating black liquor, combusting organic compounds, reducing inorganic compounds, and reconstituting cooking liquor.

Cooking liquor, which is referred to as "white liquor, is an aqueous solution of sodium hydroxide (Na01) and sodium sulfide (Na2S) that is used in the pulping area of the mill. In the pulping process, white liquor is introduced with wood chips into digesters, where the wood chips are "cooked" under pressure. The contents of the digester are then discharged to a blow tank, where the softened chips are disintegrated into fibers or "pulp. The pulp and spent cooking liquor are subsequently separated in a series of brown stock washers: Spent cooking liquor, referred to as "weak black liquor, from the brown stock washers is routed to the chemical recovery area. Weak black liquor is a dilute solution (approximately 12 to 15 percent solids) of wood lignins, organic materials, oxidized inorganic compounds (sodium sulfate (Na2SO4), sodium carbonate (Na2003)), and white liquor (Na2S and Na0H).

In the chemical recovery cycle, weak black liquor is first directed through a series of multiple-effect evaporators (MEE's) to increase the solids content to about 50 percent. The "strong. (or "heavy") black liquor from the MEE's is then either oxidized in the BLO system if it is further concentrated in a DCE or routed directly to a concentrator (NDCE). Oxidation of the black liquor prior to evaporation in a DCE reduces emissions of TRS compounds, which are stripped from the black liquor in the DCE when it contacts hot flue gases from the recovery furnace. The solids content of the black liquor following the final evaporator/concentrator typically averages 65 to 68 percent.

Concentrated black liquor is 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 (13,500 to 15,400 kilojoules per kilogram (kJ/kg) of dry solids (5,800 to 6,600 British thermal units per pound {Btu/lb} of dry solids)), 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. Particulate matter (PM) (primarily Na2SO4) exiting the furnace with the hot flue gases is collected in an electrostatic precipitator (ESP) and added to the black liquor to be fired in the recovery furnace. Additional makeup Na2SO4, or "saltcake," may also be added to the black liquor prior to firing.

Molten inorganic salts, referred to as "smelt," collect in a char bed at the bottom of the furnace. Smelt is drawn off and  dissolved in weak wash water in the SDT to form a solution of carbonate salts called "green liquor," which is primarily Na2S and Na2CO3. Green liquor also contains insoluble unburned carbon and inorganic Impurities, called dregs, which are removed in a series of clarification tanks.

Decanted green liquor is transferred to the causticizing area, where the Na2CO3 is converted to NaOH by the addition of lime (calcium oxide [Ca0]). The green liquor is first transferred to a slaker tank, where Ca0 from the lime kiln reacts with water to form calcium hydroxide (Ca(OH)2). From the slake, liquor flows through a series of agitated tanks, referred to as causticizers, that allow the causticizing reaction to go to completion (i.e., Ca(OH)2 reacts with Na2CO3 to form NaOH and CaCO3).

The causticizing product is then routed to the white liquor clarifier, which removes CaCO3 precipitate, referred to as "lime mud." The lime mud, along with dregs from the green liquor clarifier, is washed in the mud washer to remove the last traces of sodium. The mud from the mud washer is then dried and calcined in a lime kiln to produce "reburned" lime, which is reintroduced to the slaker. The mud washer filtrate, known as weak wash, is used in the SDT to dissolve recovery furnace smelt. The white liquor (NaOH and Na2S) from the clarifier is recycled to the digesters in the pulping area of the mill.

At about 7 percent of kraft mills, neutral sulfite semi-chemical (NSSC) pulping is also practiced. The NSSC process involves pulping wood chips in a solution of sodium sulfite and sodium bicarbonate, followed by mechanical de-fibrating. The NSSC and kraft processes often overlap in the chemical recovery loop, when the spent NSSC liquor, referred to as "pink liquor," is mixed with kraft black liquor and burned in the recovery furnace. In such cases, the NSSC chemicals replace most or all of the makeup chemicals. For Federal regulatory purposes, if the weight percentage of pink liquor solids exceeds 7 percent of the total mixture of solids fired and the sulfidity of the resultant green liquor exceeds 28 percent, the recovery furnace is classified as a "cross-recovery furnace.'" Because the pink liquor adds additional sulfur to the black liquor, TRS emissions from cross recovery furnaces tend to be higher than from straight kraft black liquor recovery furnaces.

Chemical Recovery in Black Liquor Processing for Pulp and Paper Production

Pulp and paper mill
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.”

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
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. 

Inline Refractometers for the Production of Jams and Jellies

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
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

DCR E-Scan
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.

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

Happy Customer Service
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.