Showing posts with label pulp & paper. Show all posts
Showing posts with label pulp & paper. Show all posts

Top 5 Reasons TECO Consistency Transmitters Stand Above the Competition

  1. TECO Consistency Transmitters are shipped with built-in flow-rate compensation. This is important because blade style consistency sensors are sensitive to shifts in production flow-rate. This means that their output has a component which is strictly a function of flow-rate. If this isn’t compensated for, changes in flow-rate will look like changes in consistency. TECO Consistency Transmitters include a flow-rate input so that this flow-rate function which automatically gets applied to the consistency signal. This feature is unique to TECO.
  2. The key feature of our C3000 and C5000 probe style sensors is that they aren't sensitive to flow-rate changes to begin with. The C3000 and C5000 are insensitive to shifts in production flow-rate below 3.0 fps. This means that as long as the flow-rate stays below 3.0 fps, shifts in flow-rate will not produce any negligible affect on the probe output signal. For flow-rates above 3.0 fps when using C3/5000 series sensors, it is recommended that active compensation be used.
  3. The C5000 sensor is retractable, allowing it to be removed from an active process. This feature is particularly useful when installed in hostile measurement environments, such as blow lines and bleach plant operations. The retractable feature allows for quick change-out when it comes time for replacement, allowing the restoration of a critical measurement in minutes, instead of waiting weeks or months for a scheduled shutdown. This is a strong competitive advantage for C5000 users.
  4. All TECO sensors are hot-swappable, saving the time and effort of a recalibration procedure when a sensor is replaced. All that is required is use the built-in normalization procedure and "zero" the replacement sensor. Your new sensor is ready to use.
  5. TECO consistency transmitters can be upgraded to act as a consistency controller, or function as multi-input controller, so that other process parameters can be adjusted for in the consistency control loop.
More Reasons:
  • TECO consistency transmitters can also be set up as a dilution controller.
  • 100% Made in the USA. 
  • TECO consistency transmitters are very competitively priced.
More information at https://teco-inc.com
800-528-8997

Stock Prep Solutions - Helping Paper Manufacturers Stay in Business

Stock Prep
The concept behind stock prep is to manage the raw materials being added to the process so the finished stock meets the requirements of the paper machine and the final quality of the finished product. Finished stock is a suspension of fibers, additives, and impurities matching a defined level of quality, which ultimately determines the operation of the machinery and the quality of the final product. Most of the machines used for individual processes provide not only the desired effect, but also may produce undesirable side-effects. Implementing process controls to reduce or eliminate these undesirables help paper producers gain considerable improvements in quality, consistency, and yield.

This video introduces, and presents a case for, specific process instrumentation designed for stock prep.

http://www.teco-inc.com
800-528-8997

Understanding the Chemical Recovery Processes in Pulp & Paper Mills

chemical reclaim pulp and paper process
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)
The relationship of the chemical recovery cycle to the pulping and product forming processes is
chemical reclaim pulp and paper process
Figure 2
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.

With over 70 years experience, Thompson Equipment Company, Inc. (TECO) provides specialized instrumentation, magnetic flow meters, and re-manufactured process instruments used in the pulp and paper industry. For information on process control instruments, valves, or service or calibration, visit http://www.teco-inc.com or call 800-528-8997.

Paper Production: Measuring Freeness Produces More Salable Product

Measuring Freeness improves quality
Measuring Freeness improves quality in paper production.
Better quality and more salable paper is the outcome of accurately measuring freeness at the beginning of the manufacturing process. Controlling freeness makes production lines more efficient and capable of producing better quality paper at a lower cost per ton.

According to the North Carolina State Mini-Encyclopedia of Papermaking Wet-End Chemistry, freeness is defined as “a measure of how quickly water is able to drain from a fiber furnish sample. In many cases there is a correlation between freeness values and either (a) a target level of refining of pulp, or (b) the ease of drainage of white water from the wet web, especially in the early sections of a Fourdrinier former. Standard tests of freeness are based on gravity dewatering through a screen. The devices are designed so that an operator can judge the speed of dewatering by observing the volume of liquid collected in a graduated cylinder. Freeness tends to be decreased by refining and by increases in the level of fines in the furnish. Freeness can be increased by use of drainage aids, removal of fines, or enzymatic treatments to convert mucilaginous materials into sugars."

TECO (Thompson Equipment Company) has been serving the pulp and paper industry for over 60 years, and has helped hundreds of clients with their unique Drainac® Drainage Rate Indication System. The Drainac® is an on-line instrument that continually measures the drainage rate of pulp and provides a proportional 4-20 mA DC signal. The unit consists of two major sub-assemblies; a detector and a detector control cabinet. It has earned a reputation as the fastest, lowest cost, and most pain-free device of its kind for measuring freeness.

Basic Applications

Closed Loop Refiner Controls – On-line freeness measurement is commonly used to control the final freeness target (setpoint) for the refiners by cascading the freeness measurement output directly to the horsepower tons / day controller.

Basic On-line Freeness Measurement – Basic on-line freeness measurement is used by production managers and paper machine operators as a “speedometer” of fiber quality enabling them to make real- time decisions that effect final production quality and paper machine run-ability.

Stock Blending – Used for monitoring the fiber characteristics of individual furnish streams so that optimal stock blending can be accomplished on a real-time basis. In this manner, the lower cost furnish stream can be maximized without sacrificing final product quality.

Please watch the video below for a better understanding of why its important to measure freeness for improved paper quality. For more information on freeness measurement, visit http://www.drainac.com or call TECO at 800-528-8997.


Accurate Pulp Mill Consistency Measurement Required

samples taken from the defiberlizer
The graph above displays the actual
results from lab verification samples
taken from the defiberlizer.

Problem / Issue:
Pulp Mill Consistency Measurement Requires Accurate Measurement over a Wide Range of Consistency Levels.

Overview:
The overall throughput (TPD) of the fiber line is traditionally calculated from a single consistency measurement device. This measurement must be accurate and repeatable.

TECO Solution:
C9700 Fixed Wing Consistency Sensor.

How the TECO Solution Solves The Problem...
The TECO C9700 Fixed Wing Consistency Sensor is designed to accurately measure over a wide consistency range, including low consistency swings from variations in blow tank levels. This sensor has proven consistency ranges from 1.5 % to 7.0%, over a wide range of velocity (flow) rates.

As an example, the above graph displays the results from a southern kraft pulp mill application, after the blow tank, prior to the defiberlizer.

Benefits
  • Wide Consistency Range – accurate across a variety of consistency levels
  • Simple / Reliable Probe Design – no moving parts or maintenance issues
  • Stable Calibration and Excellent Repeatability – for complete consistency control

Who is it Important to?
  • Pulp Mill Superintendent
  • Bleach Plant Superintendent 
  • Process Control Engineer
  • Maintenance Manager
  • Instrument Superintendent

TECO HK Series Microwave Consistency Transmitter Technical Review

TECO HK Series microwave consistency transmitters
TECO HK Series
Microwave Consistency Transmitters
The TECO HK Series microwave consistency transmitters provide a versatile, safe and easy-to-calibrate means for measuring the consistency of paper stock. The HK Series can successfully measure broke, recycle or other difficult fiber types, independent of fiber length, freeness or wood species.

Typically less than half of the cost of other microwave transmitters, the HK series microwave transmitters will measure the percentage of total solids of additives in water and percentage of moisture in wood chips with the same transmitter. Applications include measurement and control of machine, recycle & broke stock, measurement and control of % totals solids of starch additives, measurement and control of % solids (limestone, kaolin clay) in coatings.
  • Low cost – typically less than half the cost of other microwave transmitters
  • Easy to install
  • One point calibration
  • Adjustable antenna units to maximize sensitivity to process conditions
  • Internally compensated for temperature
  • No routine maintenance required. Install & forget!
  • Current and Digital Outputs
  • Contact closure
  • Versatile – Same transmitter can be used in Pipes, tanks, chests, belts & chutes.
Applications:

  • Paper and Board Mills:
    • Machine Stock Consistency Measurement and Control
    • Broke Consistency Measurement and Control
  • Paper Mills
    • Bleaching State Feed Consistency
    • Consistency Measurement & Control in Fiber Lines with changing Wood Species
    • Production Measurment at Integrated Mills
  • Mechanical Pulp Plants
    • Refiner Consistency
    • All Fiber Line Consistency Measurments and Control
  • De-inking Pulp Plants
    • Consistency and Control of Deinking Pulp
    • Production Measurement of Deinking Pulp