In recent years, China's paper industry has developed rapidly. However, the shortage of raw materials, serious environmental pollution, and lack of energy have constrained the development of the paper industry to some extent. The waste paper raw materials known as “urban forest†are increasingly valued by large and medium-sized enterprises at home and abroad. Extensive recycling of waste paper is an effective way for the pulp and paper industry at home and abroad to expand production scale, save energy, improve economic efficiency, and create social benefits.
The overall requirements for modern waste paper processing equipment At present, there are many types of waste paper. Due to the different types of products and the different technological processes used, the paper produced by waste paper is quite different, but the requirements for modern waste paper of different types of processing equipment are different. But it has its common features.
1. As far as possible, the fibers in the waste paper are not damaged to a great extent, and it is required that the disintegration and defoliation equipment have high efficiency, save power, and ensure the physical properties of the paper.
2. All kinds of light and heavy impurities in waste paper should be removed as soon as possible. The equipment such as screening and deslagging should be highly efficient. The disintegration equipment should separate the fibers as much as possible without breaking the impurities.
3. Restore the original whiteness of waste paper as much as possible, use high-efficiency flotation, washing, and bleaching equipment to separate fibers from ink, and ink residue and waste water are easy to handle.
4. Simplify the pulping process, reduce the consumption of water, electricity, gas, and medicine, increase the slurry yield, and reduce costs.
Two typical waste paper processing processes analyze China's use of waste paper to produce paperboard and medium-to-high-grade cultural paper. Although it started late, it has developed rapidly. In recent years, a feasible process has been formed, and domestic equipment support is basically satisfactory. The technology needs, can replace the import, and the price is only 1/5-1/7 of imported equipment, has created good conditions for the full utilization of waste paper at home and abroad, and has been recognized by users.
1. Cardboard production process using old corrugated box (OCC):
The main features of this process are the analysis of the repulping system: it consists of a hydraulic pulper, a deep slag well, an impurity separator, and a cylinder screen. Waste paper is fed to a hydraulic pulper through a belt conveyor, and the hydraulic pulper rotor generally uses energy. Type PSVokds rotor, waste paper is broken down under the mechanical action of the rotor blade and hydraulic shear, the concentration is generally controlled below 3%, continuous operation. The disintegrated slurry is pumped out and sent to a high consistency cleaner. There is a heavy slag hole at the bottom of the hydraulic pulper tank. Heavy impurities in the waste paper enter the sedimentation well from the heavy slag hole, and some fibers and light impurities are separated and floated into the sediment separator to enter the impurity separator. Under the action of its rotor, The good slurry enters the upper process through the sieve plate. The coarse debris and some fibers are trapped in the impurity separator. After regular flushing, they are sent to the cylindrical sieve for dewatering and discharged. The cylindrical sieve recovers the fiber and feeds it to the hydraulic pulper. The machine is generally equipped with a rope twister for continuous operation, which can effectively remove coarse impurities such as iron wire, string, and cotton yarn in waste paper.
The combination of several devices in the system can avoid the fine-grained impurities in the pulping process, reduce the burden on the equipment after the sequence, and improve the processing capacity of the disintegration system.
Coarse screening system: including high concentration slag remover and double fiber separator. High-concentration pressure screen, medium concentration cleaner, light residue separator. The main function of this system is to separate and remove lighter and heavy impurities of larger size contained in the disintegrated slurry. First, the disintegrated slurry enters the high-concentrate cleaner in a tangential direction under a certain pressure. Due to the heavy weight and large inertia, it is not easily affected by slurry scouring and moves with the slurry. Using the eddy current principle, various heavy impurities such as staples and stones can be effectively removed at concentrations of 3-5%. It is a protective device and is therefore placed at the front of the process to protect the device from being damaged. damage.
The slurry after high deconcentration dregs is pumped into the multi-fiber separator, and the multi-fiber separator integrates slag removal, slag removal and screening functions, and can further dissipate the paper that has not been completely disintegrated after disintegration. , And can effectively remove heavy debris such as residual sand, gravel, and light impurities such as plastics, polystyrene foam, and some stickies, so as to reduce the burden on subsequent screening equipment. The good slurry enters the high-concentration pressure screen, and the tailings and light impurities enter. Light residue separator.
The high-consistency pressure screen generally adopts a drum-type closed rotor, which can prevent impurities from being entangled in operation, and does not reduce the freeness of the pulp. It can be screened at a concentration of 1.5-4%, and the good slurry enters the medium-density cleaner. To further remove impurities that have not been sieved in the previous process, especially heavy impurities, one or two stages are generally used.
The main function of the light residue separator is to treat the tailings and light impurities of the compound fiber separator, the high-concentration pressure screen, the pressure finishing screen, and to remove the polystyrene foam, plastic sheet, and part of the sticky material by using the rising eddy current principle, and recovering. fiber.
Fine screening system: It is composed of a two-stage pressure fine screen, a low-consistency slag remover, and a gravity-type rotary screen compactor or a secondary pulp washer. The function of this system is to remove fine impurities that have not been removed in the rough screening and high concentration cleaner system. The pressure fine sieve is generally selected by the corrugated sieve, and used in combination with the high-concentration pressure sieve (hole sieve) in the previous process, which can effectively remove large, long-shaped or sheet-shaped impurities, and can also effectively remove the group of impurities, Adhesive impurities, fiber bundles and other small impurities. Light impurities are sent to the light slag separator and the slurry is pumped to a low consistency cleaner.
The low-concentrate slag cleaner here is mainly to remove fine light impurities such as polystyrene foam, plastic sheets and part of stickies. The role of gravity rotary screen thickener or secondary pulp washer is to use washing on the one hand. The method further removes fine impurities and dust from the slurry and, on the other hand, concentrates the slurry to the concentration required for the thermal dispersion system.
Thermal dispersion system: After the hot slurry is processed by the previous process, more than 90% of the impurities are removed, but the adhesive impurities in the waste paper still remain in the pulp, such as grease, paraffin, plastic, rubber, asphalt, etc. The method of screening and removing slag is removed. If no measures are taken, these hot melts are dried at a high temperature during the papermaking process and are melted at a high temperature. This not only results in operational problems such as sticking to the cylinder and breaking the head, but also causes different degrees of hot melt spots on the surface of the paper. Affects the appearance of the paper directly. The function of the thermal dispersion system is to disperse these impurities into noise spots that cannot be seen by the human eye below 40 μm. It includes three types of equipment: oblique spiral thickeners, screw presses, and heat dispersers. The concentration of slurry spiral helix concentrator and screw pulper is increased to about 30%, and it is sent to a thermal disperser. The heat disperser has a special-shaped stator and rotor, and it is strongly pressed and rubbed in the heated state, and the former The adhesive impurities that have not been removed in the process are hot-melt dispersed and uniformly distributed in the slurry. Heating temperature of about 90 °C, can basically maintain the characteristics of the fiber.
Summarizing the above analysis, the new technologies used in the above processes include the following aspects: The smashing of the pulping system can be carried out at the same time to remove coarse impurities as soon as possible to avoid impurity interference and finely divided impurities, thereby reducing the burden on subsequent equipment and improving the system's production capacity; Multi-stage screening removes various impurities as much as possible to reduce the burden of the thermal dispersion system; the screening system can remove impurities from coarse to fine, from large to small, from heavy to light, from many to small, from easy to difficult The effective sequence is conducive to impurity screening; the use of thermal dispersion technology, can be difficult to remove the hot melt dispersion treatment, improve the appearance of paper quality and the operating performance of the paper machine, it can also be said that the heat disperser is the entire system to deal with various impurities The last gated equipment. (Shandong Jining Light Industry Machinery Factory Liu Wei)
The overall requirements for modern waste paper processing equipment At present, there are many types of waste paper. Due to the different types of products and the different technological processes used, the paper produced by waste paper is quite different, but the requirements for modern waste paper of different types of processing equipment are different. But it has its common features.
1. As far as possible, the fibers in the waste paper are not damaged to a great extent, and it is required that the disintegration and defoliation equipment have high efficiency, save power, and ensure the physical properties of the paper.
2. All kinds of light and heavy impurities in waste paper should be removed as soon as possible. The equipment such as screening and deslagging should be highly efficient. The disintegration equipment should separate the fibers as much as possible without breaking the impurities.
3. Restore the original whiteness of waste paper as much as possible, use high-efficiency flotation, washing, and bleaching equipment to separate fibers from ink, and ink residue and waste water are easy to handle.
4. Simplify the pulping process, reduce the consumption of water, electricity, gas, and medicine, increase the slurry yield, and reduce costs.
Two typical waste paper processing processes analyze China's use of waste paper to produce paperboard and medium-to-high-grade cultural paper. Although it started late, it has developed rapidly. In recent years, a feasible process has been formed, and domestic equipment support is basically satisfactory. The technology needs, can replace the import, and the price is only 1/5-1/7 of imported equipment, has created good conditions for the full utilization of waste paper at home and abroad, and has been recognized by users.
1. Cardboard production process using old corrugated box (OCC):
The main features of this process are the analysis of the repulping system: it consists of a hydraulic pulper, a deep slag well, an impurity separator, and a cylinder screen. Waste paper is fed to a hydraulic pulper through a belt conveyor, and the hydraulic pulper rotor generally uses energy. Type PSVokds rotor, waste paper is broken down under the mechanical action of the rotor blade and hydraulic shear, the concentration is generally controlled below 3%, continuous operation. The disintegrated slurry is pumped out and sent to a high consistency cleaner. There is a heavy slag hole at the bottom of the hydraulic pulper tank. Heavy impurities in the waste paper enter the sedimentation well from the heavy slag hole, and some fibers and light impurities are separated and floated into the sediment separator to enter the impurity separator. Under the action of its rotor, The good slurry enters the upper process through the sieve plate. The coarse debris and some fibers are trapped in the impurity separator. After regular flushing, they are sent to the cylindrical sieve for dewatering and discharged. The cylindrical sieve recovers the fiber and feeds it to the hydraulic pulper. The machine is generally equipped with a rope twister for continuous operation, which can effectively remove coarse impurities such as iron wire, string, and cotton yarn in waste paper.
The combination of several devices in the system can avoid the fine-grained impurities in the pulping process, reduce the burden on the equipment after the sequence, and improve the processing capacity of the disintegration system.
Coarse screening system: including high concentration slag remover and double fiber separator. High-concentration pressure screen, medium concentration cleaner, light residue separator. The main function of this system is to separate and remove lighter and heavy impurities of larger size contained in the disintegrated slurry. First, the disintegrated slurry enters the high-concentrate cleaner in a tangential direction under a certain pressure. Due to the heavy weight and large inertia, it is not easily affected by slurry scouring and moves with the slurry. Using the eddy current principle, various heavy impurities such as staples and stones can be effectively removed at concentrations of 3-5%. It is a protective device and is therefore placed at the front of the process to protect the device from being damaged. damage.
The slurry after high deconcentration dregs is pumped into the multi-fiber separator, and the multi-fiber separator integrates slag removal, slag removal and screening functions, and can further dissipate the paper that has not been completely disintegrated after disintegration. , And can effectively remove heavy debris such as residual sand, gravel, and light impurities such as plastics, polystyrene foam, and some stickies, so as to reduce the burden on subsequent screening equipment. The good slurry enters the high-concentration pressure screen, and the tailings and light impurities enter. Light residue separator.
The high-consistency pressure screen generally adopts a drum-type closed rotor, which can prevent impurities from being entangled in operation, and does not reduce the freeness of the pulp. It can be screened at a concentration of 1.5-4%, and the good slurry enters the medium-density cleaner. To further remove impurities that have not been sieved in the previous process, especially heavy impurities, one or two stages are generally used.
The main function of the light residue separator is to treat the tailings and light impurities of the compound fiber separator, the high-concentration pressure screen, the pressure finishing screen, and to remove the polystyrene foam, plastic sheet, and part of the sticky material by using the rising eddy current principle, and recovering. fiber.
Fine screening system: It is composed of a two-stage pressure fine screen, a low-consistency slag remover, and a gravity-type rotary screen compactor or a secondary pulp washer. The function of this system is to remove fine impurities that have not been removed in the rough screening and high concentration cleaner system. The pressure fine sieve is generally selected by the corrugated sieve, and used in combination with the high-concentration pressure sieve (hole sieve) in the previous process, which can effectively remove large, long-shaped or sheet-shaped impurities, and can also effectively remove the group of impurities, Adhesive impurities, fiber bundles and other small impurities. Light impurities are sent to the light slag separator and the slurry is pumped to a low consistency cleaner.
The low-concentrate slag cleaner here is mainly to remove fine light impurities such as polystyrene foam, plastic sheets and part of stickies. The role of gravity rotary screen thickener or secondary pulp washer is to use washing on the one hand. The method further removes fine impurities and dust from the slurry and, on the other hand, concentrates the slurry to the concentration required for the thermal dispersion system.
Thermal dispersion system: After the hot slurry is processed by the previous process, more than 90% of the impurities are removed, but the adhesive impurities in the waste paper still remain in the pulp, such as grease, paraffin, plastic, rubber, asphalt, etc. The method of screening and removing slag is removed. If no measures are taken, these hot melts are dried at a high temperature during the papermaking process and are melted at a high temperature. This not only results in operational problems such as sticking to the cylinder and breaking the head, but also causes different degrees of hot melt spots on the surface of the paper. Affects the appearance of the paper directly. The function of the thermal dispersion system is to disperse these impurities into noise spots that cannot be seen by the human eye below 40 μm. It includes three types of equipment: oblique spiral thickeners, screw presses, and heat dispersers. The concentration of slurry spiral helix concentrator and screw pulper is increased to about 30%, and it is sent to a thermal disperser. The heat disperser has a special-shaped stator and rotor, and it is strongly pressed and rubbed in the heated state, and the former The adhesive impurities that have not been removed in the process are hot-melt dispersed and uniformly distributed in the slurry. Heating temperature of about 90 °C, can basically maintain the characteristics of the fiber.
Summarizing the above analysis, the new technologies used in the above processes include the following aspects: The smashing of the pulping system can be carried out at the same time to remove coarse impurities as soon as possible to avoid impurity interference and finely divided impurities, thereby reducing the burden on subsequent equipment and improving the system's production capacity; Multi-stage screening removes various impurities as much as possible to reduce the burden of the thermal dispersion system; the screening system can remove impurities from coarse to fine, from large to small, from heavy to light, from many to small, from easy to difficult The effective sequence is conducive to impurity screening; the use of thermal dispersion technology, can be difficult to remove the hot melt dispersion treatment, improve the appearance of paper quality and the operating performance of the paper machine, it can also be said that the heat disperser is the entire system to deal with various impurities The last gated equipment. (Shandong Jining Light Industry Machinery Factory Liu Wei)
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