RU2817328C1 - Method and device for fluffing cellulose-based materials - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to processing of sheet materials based on cellulose for use in chemical or paper industry, production of construction materials and relates to a method and a device for producing fluffed cellulose. Cellulose sheets are treated with impact or impact with abrasion in a grinder, mechanical classification, pneumatic transportation, sedimentation of fluffing products in a settling or filtering chamber, purification of waste air in a filter. Sheets of raw material are folded at least twice, in accordion, zigzag, stack with sheet edges shift of not less than 0.05 of sheet length, part of waste air is directed for recirculation, fresh air intake makes 5–90% of total air flow rate. Sources of sheet materials can be a cellulose folder, cellulose cardboard, cardboard, corrugated cardboard, imitation chromo board, press-board, waste paper, roll paper, separate sheets or stacks of paper. In versions of the device, a roller feeder with control of the speed of linear feed of raw materials, a hammer mill, and a centrifugal dust fan are used. Collector—woven bag or soft collapsible container is installed inside settling or filtering chamber. Two such chambers are located parallel to each other and can operate alternately in a “loading–unloading” cycle.

EFFECT: invention increases efficiency, improves quality of fluffed cellulose and reduces power consumption.

12 cl, 1 dwg

Description

The invention relates to methods for producing fluff pulp from sheet materials based on cellulose, c. incl. production of thermal insulation, for example, ecowool, as well as processing of cellulose in the production of chemical derivatives of cellulose, for example, cellulose ethers, in the production of cellulose materials used as reinforcing fillers of polymer composite materials, as well as in the pneumatic transportation of fluff cellulose. The invention can be used in the chemical or paper industry, as well as in the building materials industry.

Cellulose-based materials, incl. thermal insulation, made from cellulose or cellulose-containing raw materials, incl. from recycled materials. In this case, the feedstock can be in a dense form - in the form of compressed bales, rolled paper, flat sheets or flat sheets - the so-called (so-called) cellulose folder.

One of the characteristic properties of cellulose as a material is its fibrous form, due to the natural structure of the feedstock. Cellulose in plant raw materials is in the form of plant fibers - elongated particles with a round or multifaceted cross-section and pointed ends. In this case, the length of the fiber is many times greater than its thickness. A feature of cellulose fibers is the ease and spontaneity of aggregation. In a free state, the fibers begin to interact with each other and form hydrogen bonds, weak in nature, but in huge quantities. Therefore, cellulose-based materials have the so-called. cohesion and form aggregates - flakes or lumps. These aggregates can be destroyed and disaggregated under certain mechanical, aerodynamic or hydrodynamic influences, separating individual fibers. In the absence of such influence, as a rule, the fibers of cellulose and cellulose-based materials tend to spontaneously form a network structure. This structure underlies the flakes and lumps of cellulose raw materials.

The flocculent and lump-like structure of cellulose and cellulose materials is preferable or acceptable in the form of materials for end use - in thermal insulation layers of building structures of building manufacture, thermal insulation products, for example, slabs. When using cellulose as the reinforcing filler of a polymer composite material, the fluff form may also be preferred. Also, this form may be appropriate when carrying out chemical modification - processing cellulose with chemical reagents. The developed surface area contributes to the good reactivity of the raw material. This is advisable when producing cellulose ethers, for example, carboxymethylcellulose, polyanionic cellulose, cellulose nitrates, etc. In this case, during the technological processing, it is often necessary to have cellulose in the form of dispersed particles, i.e. in the form when cellulose aggregates are destroyed and cellulose fibers are more or less separated from each other. This is due to maintaining the required concentration gradient of chemical reagents, water, solvents during chemical processing of cellulose, during washing, impregnation with binders, filtration, dehydration, drying, hydraulic or pneumatic transportation, etc. That is, during processes associated with the formation and maintenance of gradients - concentrations, temperature, pressure, for mass transfer processes, heat transfer and hydrodynamic processes.

In this regard, for processing, cellulose and cellulosic materials are subjected to dispersion into fibers using methods of mechanical loosening or mechanical defibration or aerodynamic fluffing, as well as hydrodynamic breaking. Several analogues of the proposed method and device are known from the prior art.

For example, a method of loosening cellulose using a checker and a device for its implementation are known (Zabelin, L.V. Cotton cellulose: a textbook / L.V. Zabelin, A.P. Zakoshchikov, V.K. Postnikov - M.: TsNIINTI and TEI, 1976. - 280 pp.), carried out by loosening cotton linters, pressed into bales, the raw material for the production of cellulose. A method that includes preliminary separation of a bale of cotton linters into layers, loosening and mechanical cleaning from mechanical impurities in a checker, pneumatic transportation, and unloading in a cyclone. The checker device contains a housing with a peg rotor installed inside and a sieve deck, and also has a suction pneumatic transport with an air blower, a cyclone separator, and a collection of loosened cellulose for transporting loosening products.

The disadvantages of this method are the large volume of exhaust air emitted into the atmosphere, and the need for high productivity to clean this exhaust air, lack of performance adjustment for the loosened product, manual supply of raw materials, large peak loads on the rotor drive when loosening layers of cotton linters, low quality of the loosened product. cellulose due to the breakthrough of insufficiently loosened pieces of raw material, high energy intensity of the process, large losses of raw materials.

The disadvantage of the checker is the large volume of exhaust air emitted into the atmosphere, and the high required productivity for cleaning this exhaust air, the lack of productivity adjustment for the loosened product, manual supply of raw materials, large peak loads on the rotor drive when loosening layers of cotton linters, low quality of loosened cellulose.

There is a known method of loosening cotton cellulose using a bale ripper and a bale ripper (Physico-chemical foundations and hardware design of the production technology of pyroxylin powders. T.I. Nitrates, cellulose / Edited by G.N. Marchenko: textbook. - Kazan: FEN, 2000. - 553 p. ), which consists of loosening the bales of cotton pulp using a bale opener, pneumatic conveying with hot air, separating the loosened cotton pulp in a cyclone, collecting the cotton pulp in a hopper. The bale ripper consists of a body with a loosening chamber, inside of which there are three loosening drums with a drive, a belt conveyor for supplying raw materials for loosening, a suction pneumatic transport with an air blower for transporting loosened cellulose, a cyclone separator, and a collection of loosened cellulose. The disadvantage of this method and the bale ripper is that it is unsuitable for crushing flat sheets of cellulose or cellulose raw materials, high air consumption, high required productivity for cleaning this exhaust air, and the possibility of large pieces of raw material slipping through.

There is a known method for defibering cellulose materials and a device for defibering (Chaschilov, D.V. Experience in researching the process of defibering cellulose materials and analysis of equipment operation: from a laboratory bench to an industrial installation / D.V. Chaschilov // From chemistry to technology step by step. - 2021. - T. 2. - P. 29-39. - DOI 10.52957/27821900_2021_01_29. - EDN TIQZYB), consisting of loosening the cellulose with a pinning rotor, mechanical classification of defibre products, accumulation of defibre cellulose in a collection. The device for de-fibering contains a housing with a chamber for de-fibering, a pinning rotor with a drive, a sieve, a collection of de-fibered cellulose, and a suction chamber. The disadvantages of the method and device for de-fibering are the low productivity of the device, the inability to transport de-fiber products, manual supply of raw materials and manual unloading of de-fiber products.

There is a known method for loosening textile material (Patent No. 2547606 C1 Russian Federation, IPC D01G 11/00. Method for loosening textile material: No. 2014123132/12: application 06/09/2014: publ. 04/10/2015 / K.I. Shamin, A.A Chernov, V.G. Zotov [etc.]; applicant JSC NPO PRIBOR - EDN ZFGNOP.) The method is used for automatic fluffing of bales of cellulose and contains a forced supply of raw materials, fluffing of cellulose with rotating radial combs, and conveyor removal of bulk raw materials. The disadvantage of this method is that it is unsuitable for fluffing cellulose in the form of sheets. This method is adopted as a prototype.

The technical objective of the present invention is to develop a method for fluffing cellulose and a device for implementing this method, improving the quality of processed materials, increasing productivity, reducing losses of raw materials and reducing energy costs for the process. No devices have been identified from the prior art with the help of which the proposed method of fluffing cellulose in the declared combination of characteristics could be implemented.

The stated technical problem is solved by the fact that in the method of fluffing cellulose, including fluffing (destruction) of sheets or layers of cellulose by impact or impact-abrasion using a rotor, mechanical classification of fluffing products, pneumatic transportation of fluffing products, deposition of fluffing products in a settling or filtration chamber, additionally Exhaust air is recirculated, fresh air intake is from 5 to 90% of the total air flow; before fluffing the sheets, the sheets are first folded at least in half. Also in other embodiments, sheets of cellulose are used as the raw material supplied to the device, either bent in half and folded in half, or, in the form of a stack, bundle or package, consisting of at least not less than two sheets in a stack, bundle or package, either accordion-folded sheets or zigzag-folded sheets, which ensures that the cellulose sheet is fed in the “machine” direction, and a hammer mill is used as a grinder. The proposed method of fluffing cellulose provides increased productivity, elimination of “slippage” of insufficiently fluffed raw materials, uniformity of fluffing products, reduced losses of raw materials during processing, reduced emissions of polluted air, and reduced energy costs for the process.

Also, to solve the stated technical problem, a device for fluffing cellulose is proposed, containing a mechanism for folding sheets, a rotor, a rotary motion drive, a working chamber for fluffing, a feeding device, a separating partition, a material pipeline, a settling or filtering chamber with airtight walls, a collection of fluff pulp, and a blowing machine , recirculation air duct, exhaust air duct, filter. Also in other embodiments, a hammer mill or hammer crusher is used as an impact or impact-abrasive type shredder; a roller feeder with linear speed control is used as at least one stage of the sheet folding mechanism, including folding sheets into a bundle, stack or bag. supply of raw materials, two parallel-installed settling and (or) filtering chambers with switching shut-off valves are used, which can operate alternately according to the “loading (separation of fluff products and exhaust air) - unloading” cycle; one of the types is used as the last stage of the settling chamber soft packaging - a woven bag, a soft folding container with air-filtering walls, and also implement the placement of a woven bag, a soft folding container with air-filtering walls inside a chamber with air-tight walls; a centrifugal dust fan is used as a blowing machine.

In fig. 1 shows a diagram of the device.

The proposed device (Fig. 1) contains a sheet folding mechanism - 1, an impact or impact-abrasive type shredder - 2, a material pipeline - 3, a collection of fluff pulp - 4, a settling chamber - 5, a filter - 6, a control valve - 7, a valve - 8, blower machine - 9, recirculation air duct - 10. A material pipeline connects the grinder and the settling chamber. The settling chamber has a detachable lid on which a removable collection of fluff pulp is fixed. After the blower machine, the air duct branches, forming a loop for recirculating exhaust air and a branch for releasing exhaust air into the atmosphere. The damper on the air duct is intended, for example, to facilitate switching on the device. The regulating damper serves to control the flow of air released into the atmosphere.

The device works as follows. Using a mechanism for folding sheets, sheet raw materials are formed into a stack of one or another structure, then fed by a feeder into the working chamber of the shredder. The required productivity is ensured by adjusting the linear feed speed of raw materials. In the shredder, the pulp sheets are crushed and fluff pulp is formed. The fluff pulp is separated from the unshredded pulp pieces by a mechanical classifier, such as a shredder screen deck. The fluffy cellulose is sucked into the material pipeline due to the vacuum created by the blower. Fresh air is also sucked in and recirculated air is supplied to the working chamber of the chopper. The fluffy cellulose, together with the air, moves to the settling or filtering chamber, where the fluffy cellulose is separated from the air thanks to a collector, the air-permeable walls of which retain particles of the fluffy cellulose and allow exhaust air to pass through. A certain amount of cellulose dust passes through the walls of the collection chamber along with the exhaust air. The exhaust air then passes through a blower. Part of the exhaust air is returned to the shredder through the air duct. The other part passes through a filter, where dust is removed, and is released into the atmosphere. To regulate the amount of exhaust air emitted into the atmosphere or the ratio of exhaust air emitted into the atmosphere and sent for recirculation, a control damper is used, which can be made on the basis of a standard dust-gas-air pipeline valve with an MEO drive. The device is comparatively simple, does not emit waste air in large quantities, and reduces energy consumption for air preparation and transportation.

Processing of sheet raw materials with a greater total thickness of cellulose sheets used, folded at least in half, in other cases bent in half and folded in half, or several sheets (at least two) in a stack, or sheets folded like an accordion, or sheets folded in a "zigzag" eliminate the disadvantages inherent in other known methods and devices (limited productivity, heterogeneity of fluffing), which ultimately leads to increased productivity and increased uniformity of fluffing products.

Recirculation of exhaust air reduces the need for fresh air, reduces the loss of raw materials with exhaust air, and reduces air pollution in the production area and in the ambient air. It also reduces the amount of exhaust air sent for final cleaning before being released into the atmosphere, which allows the use of air purification devices, such as a filter, with a lower throughput. This also reduces the loss of cellulose raw materials carried away with recirculated exhaust air.

The movement of exhaust air during recirculation is ensured by the pressure difference between the air collection chamber and the cellulose fluffing chamber created by the blower. Regulation of the ratio of the flow rates of the emitted and recirculated exhaust air is ensured using, for example, a rotary valve that provides throttling of the recirculated air. Due to incomplete tightness of the joints of pneumatic transport material pipelines, air is sucked in, which eliminates the possibility of complete recirculation of exhaust air. Also, the need to release part of the exhaust air is determined by the need to let fresh air into the fluffing chamber, which eliminates the accidental release of contaminated exhaust air into the production room. The return of recirculated exhaust air occurs in the area of the fluffing chamber.

Fresh air intake, amounting to 5 to 90% of the total air flow, is intended to compensate for air losses in the pressure part of the air tract of the device. When fresh air intake is less than 5% of the total air flow, the dust content of the recirculated air greatly increases and the quality of fluff pulp decreases. When fresh air intake is more than 90% of the total air flow, the energy savings from air recirculation practically disappear.

In another embodiment, sheets of cellulose are fed for fluffing in a machine direction across the axis of the working body of the fluffing device. Cellulose sheets produced by the industrial continuous process have a non-uniform structure. On the surface of the sheet, a “machine” direction is distinguished - in the direction of movement of the machine forming the sheet, and a “transverse” direction perpendicular to this movement. Cellulose fibers are oriented in the thickness of the sheet, mainly along the “machine” direction. The properties of the cellulose sheet, such as strength, are not the same in these two directions. When the sheet is fed in the “transverse” direction, the sheet is less durable and when the working parts grab the fluffing device, large pieces of the sheet are torn off, which, getting into the fluffing chamber, cause increased loads on the working parts, their wear accelerates and energy consumption for fluffing increases. . When feeding the sheet in the “machine” direction, oriented cellulose fibers prevent the tearing of large pieces of sheet, which, if they are possibly pinched between the rotating rotor and the stationary parts of the shredder, cause sharp jumps in the power consumed by the shredder. When feeding the sheet in the “machine” direction, the sheet is uniformly fluffed without significant overloads acting on the working parts of the fluffing device. As a result, the energy intensity of the process is reduced and the quality of fluff pulp is improved.

In other options, when fluffing a sheet or several sheets, previously folded in a zigzag or accordion pattern, with at least two folds, and the direction of feeding the sheets is set along the fold line, large pieces of sheets also do not tear off, since this is prevented cellulose fibers, predominantly oriented in the machine direction. The productivity of fluff pulp is also increased.

In another embodiment, folding sheets in at least two layers of the same orientation, with a shift of the transverse edges of the sheets at a distance of at least 0.05 of the length of the sheet in relation to the arcs to each other, allows you to create a continuous flow of supplied raw materials, which increases the productivity of pulp fluffing and increases uniformity fluffing products. When the transverse edges of the sheets are shifted by a distance less than 0.05 of the sheet length, the edges of the sheets of adjacent layers are located quite close to each other and during grinding, large pieces of raw material can be torn off, which will lead to a deterioration in the quality of fluff pulp.

The use of the proposed method is possible for materials such as cellulose folder, cellulose cardboard, cardboard, corrugated cardboard, ersatz chrome, pressboard, waste paper, rolled paper, and individual sheets of paper. Moreover, these types of cardboard, folders, and paper can be either in the form of individual sheets or in the form of rolls.

Alternatively, a hammer crusher or mill can be used as an impact or impact-abrasive type shredder to fluff the cellulose sheets. The use of a hammer mill as a cellulose grinder results in increased operational reliability, since a standard design element is used, and the quality of fluff pulp is improved. The hammer mill effectively breaks down sheets of cellulose, fluffs it, and moves the fluff pulp along the surface of the classifier.

In another embodiment, as at least one stage of the sheet folding mechanism, including folding sheets into a bundle, stack or bag, a roller feeder with adjustable speed of linear feed of raw materials is used. Rollers can be smooth or grooved. When the rollers rotate, the sheets are forced to be fed into the shredder for fluffing at the required linear feed speed. This eliminates sharp fluctuations in the power consumed by the drive due to the tearing off of large pieces of raw material and their possible pinching between the rotor and the stationary parts of the chopper. Also, the roller feeder holds the folded sheets of cellulose raw material in a folded state, eliminating their possible spontaneous opening. The use of a roller feeder ensures uniform processing of raw materials, the absence of peak overloads during operation of the chopper, less power consumption for the operation of the chopper, and improved quality of fluff pulp.

In another embodiment, a centrifugal dust fan can be used as a blower. This increases the reliability of the proposed device. The dust fan is well adapted to work in dusty exhaust air conditions. The dust fan has a larger cross-sectional area of the air channels and is less prone to possible dust clogging. The elimination of clogging ensures uniform delivery of fluff pulp and the absence of aggregation of fluff pulp during these clogging, which improves the quality of fluff pulp.

In another embodiment, soft production or transport containers with a breathable body can be used as a collection of fluff pulp. This container is fixed to the neck of the lid of the settling or filtering chamber, through which fluff pulp can be supplied along with transport air. Air passes through the walls, and the fluffy cellulose is retained inside the collection. A woven bag or a soft folding container made of fabric can be used as a collection. Using a woven bag or soft collapsible container with filter walls can effectively capture cellulose fibers and separate them from the exhaust air, which will improve the quality of the fluff pulp. The placement of this woven mesh or collapsible soft container with air-filtering walls inside a chamber with airtight walls makes it technically possible to collect and remove exhaust air for its subsequent recirculation.

In the same embodiment, the use of at least two settling and (or) filter chambers with switching shut-off valves as part of the proposed device, which can operate alternately according to the “loading (separation of fluff products and exhaust air) - unloading” cycle, allows for continuity in the operation of the device, which allows increasing the productivity of fluff pulp. When the first chamber is filling, the second is unloading. Then, using switching shut-off valves, the chambers are switched. The first chamber is unloaded, and the second one is filled with fluff pulp. Then the work cycle is repeated again.

In the same embodiment, the use of a woven bag or a soft folding container with filter walls can effectively ensure the capture of cellulose fibers and their separation from the exhaust air. The placement of this woven bag or collapsible soft container with air-filtering walls inside a chamber with airtight walls makes it technically possible to collect and remove exhaust air for its subsequent recirculation. The movement of exhaust air during recirculation is ensured by the pressure difference between the air collection chamber and the cellulose fluffing chamber created by the blower. Regulation of the ratio of the flow rates of the emitted and recirculated exhaust air is ensured using, for example, a rotary valve that provides throttling of the recirculated air. Due to incomplete tightness of the joints of pneumatic transport material pipelines, air is sucked in, which eliminates the possibility of complete recirculation of exhaust air. Also, the need to release part of the exhaust air is determined by the need to let fresh air into the fluffing chamber, which eliminates the accidental release of contaminated exhaust air into the production room. The return of recirculated exhaust air occurs in the area of the fluffing chamber.

The proposed method and device for fluffing cellulose provides increased productivity, elimination of “slippage” of insufficiently fluffed raw materials and improved quality of fluffed cellulose, reduced losses of raw materials during processing, reduced emissions of polluted air, and reduced energy costs for the process.

Claims (12)

1. A method for producing fluff pulp from cellulose-based sheet materials, consisting of crushing cellulose sheets by impact or impact-abrasion, mechanical classification of fluff products, pneumatic transportation of fluff products, sedimentation of fluff products in a settling chamber, purification of exhaust air, characterized in that Before fluffing the sheets, the sheets are first folded at least twice, part of the exhaust air is recirculated by feeding it into the loosening chamber, and fresh air is taken in in an amount from 5 to 90% of the total air flow. 2. The method according to claim 1, characterized in that the sheets of cellulose, when fed for fluffing, are oriented in the machine direction across the axis of the working body of the fluffing device. 3. The method according to claim 1 or 2, characterized in that the sheets of cellulose, before being fed for fluffing, are folded like an accordion with at least two folds, the direction of feeding the sheets is set along the direction of the folds. 4. The method according to claim 1 or 2, characterized in that the sheets of cellulose are folded at least in half before being fed for fluffing, the direction of feeding the sheets is set along the direction of the folds. 5. The method according to claim 1 or 2, characterized in that the sheets of cellulose are folded in a zigzag pattern with at least two folds before being fed for fluffing. 6. Method according to claim 1 or any of claims. 2, 3, 4, characterized in that the cellulose sheets, before being fed for fluffing, are laid in at least two layers of the same orientation, with the transverse edges of the sheets shifted by a distance of at least 0.05 of the sheet length. 7. Method according to any one of paragraphs. 1-6, characterized in that at least one of the following materials is used as cellulose raw material: cellulose folder, cellulose cardboard, cardboard, corrugated cardboard, chrome ersatz, pressboard, rolled paper, individual sheets of paper. 8. A device for fluffing sheet cellulose materials according to claim 1, consisting of an impact or impact-abrasive type shredder, an air blower, a material duct, a separator, characterized in that it additionally contains a mechanism for folding sheets before submitting the sheets for fluffing, an air duct for recycling waste air. 9. The device according to claim 8, characterized in that a hammer mill or hammer crusher is used as an impact or impact-abrasive type grinder. 10. The device according to claim 8, characterized in that at least one stage of the sheet folding mechanism, including folding sheets into a bundle, stack or bag, uses a roller feeder with adjustable speed of linear feed of raw materials. 11. The device according to claim 8, characterized in that a centrifugal dust fan is used as a blower. 12. Device according to any one of paragraphs. 8-11, characterized in that it contains at least two settling and (or) filtering chambers installed in parallel with switching shut-off valves, which can operate alternately according to the cycle “loading (separation of fluff products and exhaust air) - unloading”, and the settling chamber has an internal collection with air-permeable walls and a body with air-tight walls, and the collection is inserted inside the body, the collection is made in the form of a soft container, and a woven bag or a soft folding container is used as a collection.

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