Measuring Solids in Pulp & Paper Black Liquor

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.

Reliable, 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

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.

Electron Machine Corporation Highlighted for Renewable Energy Investment

From the original article titled "Electron Machine Makes Big Investment In Umatilla Future" and reprinted with permission from The North Lake Outpost, Vol. 40, No 4.

With one eye cast to preserving its deep roots in Umatilla, and another to an efficient, competitive future, the Electron Machine Corporation recently embarked on a major upgrade of its facility. The firm, with decades of history in Umatilla manufacturing and distributing products that provide process measurement for the pulp and paper industry, the food and beverage industry, and the chemical industry, recently faced a crossroads.

Solar panel installation.

“We are a small firm. We have to be more nimble. We have to think differently to compete in the industries we’re serving,” said C.A. Vossberg, third generation of the Vossberg family who today oversees the firm’s operations.

Electron Machine HQ

Facing the need to undertake major upgrades on the company’s aging 25,000 square foot building, a large portion of which isn’t fully utilized, there was discussion about where the future should be.

“We don’t have to have a brand new building, but we need reliability,” Vossberg said, reporting of roofing issues that were hampering operations.

“We said, ‘What is best for the long term?”

Solar panel installation.

Eventually, the decision was made to fix the roof, and more. After nine months, during which countless delays brought about by Hurricane Irma made things even worse, the firm is closing in on completion of a project that features a large solar panel farm that is set to generate enough solar power to run the building.

Vossberg said the idea for solar power at the plant isn’t a new one, given the building’s large, flat roof. But technology has improved to the point to make the project more viable.
“The project is sized so that our net energy consumption over the year will be next to zero,” Vossberg said, a big positive when looking to the financial bottom line of operating at its current location.

There is a big cost to installing such a large solar system. However, Electron Machine has applied for a grant through the USDA to help offset the cost.

“They have a rural America program that encourages employees to remain there, and not move into the city,” Vossberg said. “That’s exactly what we are trying to do.”

Bird's-eye view of Electron Machine's solar charged roof.

Vossberg has been a proponent of rural job creation, supporting Lake Tech’s new manufacturing training facility in Eustis which is designed to increase employability in the manufacturing field, and can be found attending City of Umatilla functions regarding the Umatilla Municipal Airport. Electron Machine is among the users of the airport, and Vossberg has said it’s existence is an important cog in the wheel that allows his business to continue to function here.

“Being here, it’s who we are,” Vossberg said.

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.

What is the BLRBAC?

The BLRBAC stands for Black Liquor Recovery Boiler Advisory Committee. It was formed in 1961 as a non-profit trade association dedicated to improved safety of chemical recovery boilers, and their auxiliaries, through the interchange of technical knowledge, experience, and data on past and any future recovery boiler incidents.

It's formation stemmed from an alarming number of explosions, injuries, and deaths involving Black Liquor Recovery Boilers. Industry professionals from insurance companies, paper companies, and boiler companies agreed to create the BLRBAC for the purpose of generating safety procedures and guidelines that govern the operation of Black Liquor Recovery Boilers.

The BLRBAC has a number of active sub-committees that are constantly reviewing and updating their safety guidelines to reflect current technology and knowledge.

The Black Liquor Recovery Boiler Advisory Committee meets twice a year in Atlanta GA, usually the first week in April and October.

For more information about the BLRBAC, visit http://www.blrbac.org.

Important Process Instrumentation Terminology

In describing the characteristics and operation of process control instruments (such as process refractometers), it is very important to understand some common terms used in the industry. The definitions of some of the more common terms are provided below:

Accuracy: The closeness of an indicator or reading of a measurement device to the actual value of the quantity being measured; usually expressed as ± percent of the full scale output or reading.

Drift: The change in output or set point value over long periods of time due to such factors as temperature, voltage, and time.

Hysteresis: The difference in output after a full cycle in which the input value approaches the reference point (conditions) with increasing, then decreasing values or vice versa; it is measured by decreasing the input to one extreme (minimum or maximum value), then to the other extreme, then returning the input to the reference (starting) value.

Linearity: How closely the output of a sensor approximates a straight line when the applied input is linear.

Noise: An unwanted electrical interference on signal wires.

Nonlinearity: The difference between the actual deflection curve of a unit and a straight line drawn between the upper and lower range terminal values of the deflection, expressed as a percentage of full range deflection.

Precision: The degree of agreement between a number of independent observations of the same physical quantity obtained under the same conditions.

Repeatability: The ability of a sensor to reproduce output readings when the same input value is applied to it consecutively under the same conditions.

Resolution: The smallest detectable increment of measurement.

Sensitivity: The minimum change in input signal to which an instrument can respond.

Stability: The ability of an instrument to provide consistent output over an extended
period during which a constant input is applied.

Zero balance: The ability of the transducer to output a value of zero at the electronic null
point.

Process Refractometers Built to Handle the Toughest Conditions

Users agree. Electron Machine builds the most rugged process refractometer available for the pulp and paper,  food and beverage, and chemical industries.

https://electronmachine.com
352-669-3101