Canadian Standard Freeness Tester

Posted on September 2, 2014 by admin

The Canadian Standard Freeness is worldwide used for determination of the drainability of a dilute pulp suspensions of wet section in the paper machine. The rate of drainage is stated in terms of freeness. The freeness of pulp, as well as drainage rate is the measurable index of the effectiveness of refining process because it is connected to the work done on the pulp fiber during beating or refining and swelling of the fibers. This particular experiment is appropriate to all variety of pulps in aqueous suspension but especially for mechanical pulp.

The Canadian Standard Freeness test works based on the principle just like the SR-tester. The dissimilarity is that the pattern of the funnel and the orifices; moreover the wire screen is replaced by a screen Plate. The volume of test samples same like the SR-tester that is 1000 ml, but the consistency is difference, it is three grams per liter rather than two grams. The drainage Water is collected into a measuring glass (which is scaled in ml) through the side orifice outlet and represents as “freeness mI/CSF”. The Canadian Standard Freeness tester scale is marked from 0 to 1000 ml and the working range from 30 to 850 ml. To begin the drainage, unlock a vent valve rather than lifting a tightening cone upwards. A “free” stock dewaters quickly and results in a large volume in the measuring glass, corresponding to a high CSF value.

The properties of the water are different, if the consistency and temperature are change. So it is very important that the test must be performed at a specific consistency and temperature. If it is differs, it is need to be correction to obtained actual CSF value. As like SR-test it is recommended that the sample should be test twice. If the test result differs by more than 4 %, the entire test should be repeated.

In moment absolutely zero, while the total sample is locked in above the screen, the rate of drainage is zero. After the draining process begins, the draining increases to an upper limit after which it decelerates to approach zero. Subsequently all the water in the sample suspensions has exhausted throughout the screen and the fiber pad of The Canadian Standard Freeness tester.

The drainage amount of resistance of the stock is very significant mainly as it delivers information of the paper sheet that could be manufactured from the stock’. The denser the wet fiber pad and therefore the poorer the permeability, the fewer the drainage rate and the lower the freeness.

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Pulp freeness tester

Posted on August 27, 2014 by admin

The pulp freeness tester or slowness tester are extremely sensitive apparatus while applied effectively. Freeness of pulp is a measure of precisely how rapidly water can drain from a diluted fiber furnishes suspension. Drainage rate is related to the surface conditions and swelling of the fibers. On many occasions there is a correlation between freeness values and either a target level of refining of pulp or the easiness of drainage of white water through the wet web, especially in near the beginning sections of a Fourdrinier former. Standard tests of pulp freeness are based on gravity dewatering throughout a screen. The devices are designed so that an operator can judge the rate of dewatering by monitoring the volume of liquid collected in a graduated cylinder.

Freeness of pulp tends to be decreased by refining and by increase in the intensity of fines in the fiber furnish. Pulp freeness could be enhanced by use of drainage aids, elimination of fines, or enzymatic treatments to convert mucilaginous materials into glucose. The chemical pulp fibers turn into incredibly flexible by ample refining, and the fiber pad will packed in incredibly much more by the higher head in the hand sheet former than in the SR tester, and the consequent drainage time will increase correspondingly. It’s been emphasized that the standard readings of freeness or slowness keep minor similarity to the real drainage process on the paper machine wet section.

Schopper Riegler and Canadian Standard Freeness Tester are two Standard widely used pulp freeness tester. None are usually accepted for all through the paper machine. SR is dominates for chemical pulp whereas CSF is for mechanical pulp.

The Schopper Riegler (ºSR) test

schopper riegler freeness tester
Pulps schopper riegler freeness tester

The Schopper Riegler (ºSR) tester is widely used for trace the changes in the drainage speed of different chemical pulps throughout beating and refining. The refining of pulps is one of the most significant periods in the paper production process and also because it consumes considerably power and influences firmly the sheet forming and its physical properties. Variant in pH can have an effect on the chemicals controlling the pH in the process. Small amounts of electrolytes might have some substantial effect on the ºSR value.
Schopper Riegler tester has two parts; sample chamber and funnel. The upper chamber consists a sealing cone operates on a lever system and a wire screen. On the other hands the funnel consist two outlets (a bottom orifice and a side outlet), a spreader cone and a bent. Moreover a measuring glass for collect the overflow.

Two grams of pulp fibers sample is to be taken, then dilutes it up to 1000ml followed by well stirred. After that it put into the upper chamber of SR-tester. While the cone is elevated, the water drains throughout a wire screen. At the same time, the pulp fibers in the sample form a pad on the screen. The water flows into a funnel. The draining is rapid if the stock is “free” whereas it is slowly when the stock is “wet”. The design of the bottom orifice is such that a certain draining rate ought to be surpassed before there is an overflow from the side. The overflow is collected in a measuring glass. This is scaled so that 1000 ml overflow refers to 0 ºSR, and 0 ml overflow refers to 100 ºSR. Between these boundaries, the level is linear and a 10 ml increase is equivalent to 1 ºSR. working range from 10-90 ºSR. The test must also be performed at a temperature of 20 ºC. If the consistency or temperature differs, it is need to correction of obtained ºSR-value ought to be made. It is recommended that the sample should be test twice. If the test result differs by more than 4 %, the entire test should be repeated.

The freeness tester or slowness tester instruments have some serious limitations, that some people in the paper industry are not aware. The pulp freeness result usually employed far beyond what is really justified. It is necessary to understand just what the actual tools reading through studies, and also their particular issue.

Pulps schopper riegler freeness tester

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Water removal from paper fiber webs

Posted on August 21, 2014 by admin

Paper forming consists essentially of removing water from a dilute suspension of fiber and other materials by filtration, leaving the solids in form of a coherent sheet. Clearly, the rate and separation effectiveness of this water removal from paper fiber webs is significant to the economy of the process of papermaking.

Water removal from fiber webs on the paper machine is a hydro-mechanical process and which is accomplished by a sequence of mechanisms, like the wire clothes, felt or screen for drainage and so forth.

At the same time, during the papermaking the properties of the stock slurry and added chemicals also play a significant role in the water removal paper fiber webs.

For productivity in addition to the paper quality control in the paper mill, consideration of stock drainage resistance is important. The “freeness” of a stock is a extremely sensitive determine of the refining status of both chemical and mechanical pulps. Being strongly relevant to the actual thickness of the wet and consequently the dried paper web, the freeness is often a widespread used method for the guess of paper characteristics. The paper industry thus has for a long period of time strongly felt the need for rapid drainage measurement methods.

Quite a few tries happen to be made to layout model systems or stock drainage behavior on the paper machine. The original research laboratory tests regarding predicting the and still most widely used drainage testers are the SR (Schopper Riegler) slowness (or wetness) tester, and also the fairly more younger CFS (Canadian Standard Freeness) freeness tester. Over the years, quite a few various other drainage tests have been devised to further improve prophecy of water removal from paper fiber webs. It’s unlikely that any happen to be universally received. Even the traditional ones have doubtful reputation between quite a few scientists. They may nonetheless end up being very useful instrument if applied just for the purpose for which they were designed.

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Paper machine showers

Posted on May 22, 2014 by admin

Showers are used in paper machine mainly cleaning purpose. It is also used for coating, moisturizing, lubricating, bleaching, edge trimming and other functions. All the section in paper machine needs shower. Wire cloth should be free from contaminants in order to keep sufficient open area for proper drainage, surface characteristics, to quality sheet marking and longer life. Press felts should also be cleaned for reduce paper web break and longer life. Moreover, dryer clothes should also be cleaned to keep their air permeability and prevent sheet streaking due to non-uniform drying.

There are different type of paper machine showers such as needle jet, brush type, auto brush, fan jet, spring purge, pipe in pipe, air purge etc. Spray nozzle is called the heart of shower.

Brush type shower: Brush type shower can be manual system or automated system. This type of shower is perfect for use with recirculation systems or white water. Automatic Brush Shower used for lower forming fabric cleaning purpose on paper machine. An inside rotating wash set up scrubs the inner wall of the shower along with nozzle orifices to help mop trash apart. Depending on shower position different nozzles are chosen such as Needle Jet, Shower Jet, disc jet or hydraulic nozzles. Brushless shower is used for exactly where nozzle clogging will be less likely or fresh water systems.

Pipe in pipe shower: This type of shower use while the shower, feed tubes or nozzles need safety from the working environment and accidental damage. It may be used with automatic air atomizing spray nozzles or integrated strainers. Box-style shower are used during such a environments when starch spraying is required.

Air shower: Air shower is suitable for dryer cloth. Dryer Screen or clothes may be contains dust, dirt, sticky particles. They block the open area or make it sticky. As a result, there are non-uniform drying, spot in paper web or more frequent web break. A usual, broken up air shower is best for cleaning dryer fabrics.
paper machine showers
Needle Jet nozzles type shower: Needle jet nozzles have solid stream high impact performance. They are suitable for forming fabric, wire, felt, suction rolls, edge cutting, cross cut, dandy roll inside cleaning, etc.

Self cleaning nozzle : This type of nozzles are suitable for high pressure washing of forming fabrics, felts, wire cloth rolls, showers with high solids content or suspended solids in the water, color doctor, and machinery requiring washing by white liquor spray.

Straight jet nozzle: Straight jet nozzles are suitable for trimming shower spray, trim knock off shower, high pressure washing of forming fabrics, felts, and dandy roll outside cleaning.

Another used paper machine shower nozzles are Shower Jet nozzles, Vee jet nozzles, Flood jet nozzles, Flat jet nozzles, Whirl jet nozzles etc.

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Pulper

Posted on December 28, 2013 by admin

Pulper is used in different work place but in this topic we discuss about the pulper which is used in paper industries. It is called the heart of the repulping operation. Paper pulper is used for crushing virgin pulp (slabs or sheets), wastepaper processing, machine broke, deinking and pulp purification. It disintegrates the fiber by the action of mechanical operation. Among the raw materials waste paper processing is significant. Because in waste paper may be contains dust, sand, wire stapler pins, clips, nails, hooks, adhesive tapes, plastic tapes, string, un-dissolved coating and other foreign materials like asphalt wax, plastics etc. Waste paper should be free from these undesirable materials but some may be remains. If these materials mixed with the pulp and move towards into wire section; it must be creates some unwanted problems may be damage wire as well as poor quality paper sheet. Moreover centri-cleaner may be blocked, increase the paper web breaks, reduce the press felt and dryer screen performance. So the pulper has the ability to remove the contaminant.

The operation of pulper may be batch wise or continuous mode. In a batch mode operation it can be control the size, filler, dry strength additives, color etc by add a specific amount of chemicals in pulper. Surfactants are used for stock deinking. The associate chemicals of surfactants are dispersant, anti-foaming, caustic soda, Borax and sodium silicates. Dispersant prevent the ink to deposit onto the fiber; foaming agent reduce foam formation and other three chemicals caustic soda, Borax and sodium silicates enhance the action of surfactants.
pulper
There are different types of paper pulper for example Hydrapilper, Drum Hydrapulper, Broke Pulper. According to power consumption there are three kinds of pulper low, medium and high power consumption pulper. In addition we can also classify as low consistency and high consistency pulper. To buy a paper pulper someone have to trace some parameters such as  type of pulper, volume, consistency, processing capacity and motor power consumption.

Broke pulper: dry end pulp and wet end pulper are included in this type of pulper. It is used mainly to dissolving broke from the machine.

Hydrapulper: hydra pulper is dynamically balanced. They can be classified as D-type Hydrapulper, Horizontal Hydrapilper, Verical Hydrapulper, Drum Hydrapulper. D-type pulper is particularly design for dissolving old corrugated carton, boxes and mixed waste so that removes contaminant.

Drum pulper: the drum pulper can remain maximum the physical property of the fiber. It is used for disintegrating waste paper and processing deinking pulp. This type of pulper should be operated batch-wise.

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Rosin sizing agent

Posted on December 19, 2013 by admin

Rosin is acidic type sizing agent. In paper mill usually it is used as internal sizing agent. Rosin and its derivatives are cheap to produce and produced from regenerative raw materials. Hence these sizing agents are still a good number widely used of all wet-end sizing agents. Another source of “rosin” is ‘tall oil’ that is produced during kraft pulp manufacturing from softwood species. This rosin is a series of chemicals and one of the most important components of this type rosin is abietic acid, which is a partially unsaturated compound with one carboxyl group and three fused six-membered rings.

In the case of these sizing agents the degree of sizing can be controlled very easily. It has another advantage that the sizing effect is fully cured when the paper leaves the paper machine. Gum rosin is a natural product of pine trees.

The following rosin derivatives are used as sizing agent:

Fortified rosin size: Fortified rosin sizing agent is produced by the reaction with gum rosin and fumaric acid or maleic anhydride under suitable conditions. This is Diels-alder adduct which acts as a very effective sizing agent. The Diels-Alder adduct contains extra carboxyl groups and produces more proficient sizing response than the unreacted resin acids. It is common that the rosin which is extract from tall oil is fortified with fumaric acid. In this case some of the abietic acid and related compounds are converted into tricarboxylic species.

Cationic rosin size: Cationic rosin sizing agent is a effective sizing agent for paper. It decreases the consumption of additives as like alum, reduce environmental pollution by reducing discharge of acidic sewage, improve the paper quality as minimal acid is uses. Rosin soap size is a one kind of cationic rosin sizing agent.

Rosin soap size: It is sodium salts of resin acids. This rosin size is formed by neutralizing (saponifying) resin acids with NaOH or other sodium base, as like Sodium carbonate. There are different types rosin soap size are available such as extended size, paste size and dry size.

Free rosin: The carboxyl groups of resin acids are totally protonated form.

Extended size: A 50% neutralize solid product.

Dry size: A 100% neutralized dry rosin size product that dissolves easily in water.

Paste size: A 80% neutralized rosin size product.

Neutral Size Rosin: Neutral Size Rosin can be used in neutral conditions and this type rosin is suitable for the use of calcium carbonate as filler materials thus improving optical properties.

Function of rosin sizing agent: Aluminium resinate is the active component for rosin sizing agent. Aluminium sulphate or polyaluminium chloride is used after rosin sizing agent to obtain this reagent. Aluminium resinate oppose penetration the water into paper. Sizing effect can be attained by the electrostatic interactions with cellulosic surface.

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ASA sizing agent

Posted on June 25, 2013 by admin

Alkenyl Succinic Anhydride (ASA) is basic or neutral type sizing agent. It is wax like chemicals. ASA is used as internal sizing chemicals for paper. Structurally, it is unsaturated linear chain having five-membered anhydride ring and it is synthesized from Alfa-olefins and maleic anhydride. The anhydride ring has no fixd position in the chain, so it is called that ASA is a mixture of isomers. Physically it is yellowish oily like emulsion chemicals. The waxy solid tiny particles (0.5–2 mm) are dispersed into water and the emulsifications are stabilized usually by the cationic starch or another cationic hydrophilic polyelectrolyte stabilizer. Sometimes some little amount of surfactant is used in emulsification.
The reactive anhydride rings of ASA can easily goes under chemical reaction. At first it is hydrolyzed with the water. Then, it is form covalent bond with the hydroxyl groups of cellulose and forming an ester bond (b-keto esters).

The availability and the reasonably priced of calcium carbonate makes it the popular filler material. But this filler material is unstable in acidic medium; hence the usage of neutral/alkaline sizing agent like ASA is increased.

Alkaline sizing agent improve paper machine runnability, preserve paper’s dimensional stability increase resistance to water penetration, surface conditions of paper and maintain a high frictional coefficient. The Neutral/Alkaline Sizing Agent (ASA) also reduces paper machine breakdown, reduce dusting, reduce picking of vessel segments during offset printing and water recycling difficulties compare to Acidic sizing agent.

It should be followed the manufacturers instruction during storage especially temperature, humidity, water and time since ASA is hydrolyzed.

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AKD sizing agent

Posted on June 16, 2013 by admin

Alkyl ketene dimer (AKD) is most common neutral/ alkaline sizing agent. It is an Internal sizing agents. Structurally, it is unsaturated lactones and it is synthesized from fatty acids. Physically it is waxy like milky emulsion chemicals. The waxy solid tiny particles (0.5–2 mm) are dispersed into water and the emulsification are stabilized by the cationic starch or another cationic polyelectrolyte stabilizer.

The reactive lactones rings of AKD can easily goes under chemical reaction. It reacts with the hydroxyl groups of cellulose and forming an ester bond (b-keto esters).

The availability and the reasonably priced of calcium carbonate makes it the popular filler material. But this filler material is unstable in acidic medium, hence the usage of neutral/alkaline sizing agent are increased.
Recent years AKD is the most extensively used reactive sizing agent in the high quality printing papers production.

Alkaline sizing agent improves surface conditions of paper. The Neutral/Alkaline Sizing Agent (AKD) also reduces paper machine breakdown and water recycling difficulties compare to Acidic sizing agent.

The function of AKD sizing agent depends on different technological parameters such as ph value of the fiber suspension, raw materials, method of drying, temperature, time etc. AKD is much less reactive than ASA; hence it is more flexible for papermakers during usages. It means that it can be add to the thick or thin stock. However the presence of PCC in the system can lessen the efficiency of the sizing agent.

It should be followed the manufacturers instruction during storage especially temperature and time since AKD is slowly hydrolyzed.

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Kaolin clay

Posted on April 10, 2013 by admin

What is kaolin clay or china clay?
Kaolin clay is a dominant paper filler material which is derived from koalinite. It is also known as china clay, since the mineral primarily found in kao-ling, china. Another name of kaolin clay is white clay or light clay or heavy clay. The chemical formula of kaolin clay is hydrated aluminum silicate (Al2O3.2SiO2.2H2O). Hydrated aluminum silicate is also known as hydrous kaolin clay.

Hydrous kaolin clay is popular paper filler due to its low price, low abrasiveness, good availability and relatively white in color. Before 1990s it is most uses paper filler in Europe and the United States. The sources of kaolin clay are china, USA, Canada, Australia, UK, Brazil, Ukraine, Germany, Iran, Bulgaria, France, Korea, India and the Czech republic.

Calcined kaolin clay
Calcined kaolin clay is an anhydrous form of china clay and the chemical formulae is Al2O3.2SiO2. It is produced by calcinations process heating hydrous kaolin clay at 1000°C. At the end of this process brightness and the light scattering coefficient is increased. Hence improve opacity. The opacity of calcined kaolin is better than GCC or PCC and less than titanium dioxide.

Uses benefits of kaolin clay
Kaolin clay provides smooth surface of the paper, improves opacity, gloss and printability. The particles of china clay provide the paper high density, as a result reduces the coating penetration into the paper. The light scattering coefficient is increased hence increase the opacity and brightness. Less wire abrasion therefore extends life time of the wire cloth in paper machine compare with the GCC and PCC. Improve dewatering.
Kaolin clay decreases the strength of paper and creates little foam.

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Titanium dioxide

Posted on March 30, 2013 by admin

Titanium dioxide is an excellent filler material for paper mill industries. In spite of its all advantages, the uses of titanium dioxide are limited due to its exclusive price and high abrasive. It is used in such good quality papers that need high opacity, higher brightness and whiteness such as offset papers and bible papers. The molecular formula of Titanium dioxide is TiO2.

Mainly three mineral form of titanium dioxide, these are anatase, rutile and brookite. But only rutile and anatase are used in paper mill industries. Both are tetragonal crystalline system. Rutile has higher refractive index than anatase. The particle size of Titanium dioxide is range 0.25 to 0.45 micrometers.

Benefits of Titanium dioxide
Titanium dioxide has highest light scattering coefficient and refractive index among the paper filler. The light scattering coefficient is about 1035m2/kg and refractive index is 2.55-2.75. Hence it proposes highest opacity among the paper filler. Light scattering are depends on their orientation into paper sheet. Titanium dioxide has excellent brightness about 98-100 ISO. The small particle of titanium dioxide has very high brightness. In addition it has good optical density and it is improving whiteness of the paper.

Titanium dioxide has some disadvantages; it is highly expensive and relatively high abrasive. Moreover it is absorb ultraviolet light.

Since the Light scattering are depends on their orientation (how the particles are separated) into paper sheet. So it must be well dispersed before and after it is added. Titanium dioxide paper filler is anionic. Hence to protect from agglomeration, it should be avoid from cationic materials during premature mixing.

Specification of titanium dioxide

  1. Physical appearance: odorless white powder
  2. Density: 4.23 gm/cm2
  3. Solubility in water: 0.5% max.
  4. pH value: 6.5-8.5
  5. Volatile at 105°C: 0.5% max
  6. Titanium dioxide content (base on dry basis): 98%
  7. Brightness (ISO): 98% min.
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