The Hydra-Sizer sizing device is a newly developed device that uses curtain coating technology to impregnate auxiliaries such as starch and other chemicals on paper and board. This device is used in the wet end of a paper machine.
The addition of auxiliaries to paper and paperboard should be well coordinated with the addition method so as to obtain a large amount of addition, high retention, uniform distribution of the auxiliaries in the transverse and longitudinal direction of the paper, and control of dispersion through the thickness of the paper. At the same time, the papermaking process will not be affected by the addition of additives. In the past, the common method of joining was to add in the headbox, spray on the long wire, and sizing on the surface of the dryer section. Although many of these methods can be used, each method has its own limitations. The dispersion of the headbox is good, but the retention rate is low, and the maximum amount can not be obtained. Sprayed on the long net, the distribution is not uniform, from the microscopic point of view, drug droplets sprayed on the paper in some places can not be sprayed; from the macro point of view, in order to spray evenly, the nozzle and the nozzle must overlap. The racks are not clean and the maintenance workload is large, which can easily lead to nozzle clogging and limit the amount of application. Although the surface sizing can achieve a high amount of application. Less desirable is that the sheets are re-humidified, which means that additional drying is required, and if the speed of the paper machine remains unchanged, the drying section must be costly.
The new development Hydra-Sizer is a newly developed sizing device that uses curtain coating technology to apply up to 75 kilograms of starch or other auxiliaries per ton of paper at the papermaker's wet web. The suspension is extruded from the slits of the die mounted on the square grid. The starch solution falls a few inches like a full screen curtain onto the wet pulp. Starch is combined with wet paper stock and retained. In order to maintain the dryness at the roller, it is necessary to have some auxiliary vacuum boxes and flat vacuum boxes. However, the dryness of the web in the press section can be guaranteed without the need for additional drying cylinders.
Hydra-Sizer System The Hydra-Sizer system consists of a special set of die heads, adjustable brackets, receiving trays and additive supply systems.
The inside of the die is designed to create a flush flow structure to suspend the starch or other suspension and to avoid clumping and plugging of the die. The liquid enters from one end and is fed from the other end. The die can be opened and cleaned with an electric device. The width of the die must be greater than the net width of the roll, so that the excess auxiliaries can be recovered at the wet roller pit. The die can be attached to the edger at any width to minimize circulation. The die is above the catch plate. After starting, the curtain flows back until a uniform full curtain is formed. The die is then moved onto the web and the production process begins. The height of the die can be controlled by the electric jack to control the descent speed of the curtain. The die head is integrally connected with the walking platform. The position of the die can be determined along the direction of the long web to adapt to the change of the concentration of the application agent.
The die feed system is pre-wired with a good tube cloth and is mounted on the bottom rail. All controls are located on the track. The system has a small tank with a stirrer to keep the aid suspended. The suspension is pumped through a set of filters that can be purified in high-speed flow, followed by an air separator, heat exchanger, and the last filter installed in front of the die. The last filter ensures that lumps formed after the initial filter do not enter the die. The last filter does not need to be cleaned unless it is during flushing. All pipes behind the filter are specially designed to prevent briquettes from entering. The air separator is a patented Coating Air Separation system. This system is capable of separating small air bubbles. The paint air separator itself has recently been developed to minimize the flow required to form curtains on the die. This allows the curtain technology to apply minimal amounts of water to the paper, avoiding lower sheet dryness. A heat exchanger is provided; the suspension can be heated to 65 degrees Celsius to increase the drainage of the net, which is heated with water at 90 degrees Celsius to ensure no spots are present.
The Hydra-Sizer test To date, the first objective of the test has been to add starch to waste paper made of corrugating medium and linerboard in order to improve its strength properties. The test was conducted on a fully equipped pilot tester, which produced a variety of papers at the official production speed, and also tested on two industrially produced paper machines, most of which installed a 1-meter-wide die on the edge of the paper. Head to test. A full width die was tested.
The test was carried out using a layer of paper and two layers of paper, using only a long web, a long web, and a wet top of a top net former. Experiment with different types of starch. The best result is simple, inexpensive uncooked corn starch. Starch is added below the expansion humidity. Starch is retained on the paper and cooked in the dry section, resulting in a retention rate of 85%. The location of the starch on the screen can be from close to the headbox to near the roll. Through experiments, it was found that the paper sheet thickness affects the distribution of dryness of paper sheets on the web, and the dryness distribution can be controlled. Tests have shown that the pressing section and the drying section are not contaminated.
The results of standard tests for the production of 127 g/m2 of corrugated medium paper using mixed waste paper and OCC are shown in Tables 1 and 2. The ratio of mixed waste paper to OCC is 50:50. When the amount of lower auxiliaries is 32 kg per ton of paper, the transverse short-pitch compressive strength (CD STF1) of corrugated medium paper is increased by 10%. Concora test of corrugated medium paper has flat compressive strength. (CMT) increased by 25%. The relatively weak ratio is 80:20 ratio of mixed waste paper to OCC and 45 kg per ton of paper. The CDSTFI is increased by 20% and the CMT is increased by 30%. The results shown in Table 2 are two corrugated cores. Paper is made with 100% OCC; the amount of auxiliaries added is 50 kg per ton of paper. The 127 g/m2 and 205 g/m2 CMT and the corrugated paper crush test (CFC) both increased 28-29%.
Conclusion The application of starch by this new technology can reach the application rate that could only be achieved with the size press in the past. It provides significantly uniform sizing and can be controlled by the thickness of the paper, resulting in high retention. In wrapping paper, it can increase the strength by 25-30%, and it also loses the drying ability, making it an ideal solution for the transformation of existing paper machines. This technique is also helpful for the application of other additives such as pigments and fillers, internal sizing agents, and the like. It uses starch sizing and can be extended to other varieties, such as newsprint and high-grade cultural papers, to reduce lint. The first production device is being manufactured and is planned to be installed in the fall of 1997 to produce packaging paper.
The addition of auxiliaries to paper and paperboard should be well coordinated with the addition method so as to obtain a large amount of addition, high retention, uniform distribution of the auxiliaries in the transverse and longitudinal direction of the paper, and control of dispersion through the thickness of the paper. At the same time, the papermaking process will not be affected by the addition of additives. In the past, the common method of joining was to add in the headbox, spray on the long wire, and sizing on the surface of the dryer section. Although many of these methods can be used, each method has its own limitations. The dispersion of the headbox is good, but the retention rate is low, and the maximum amount can not be obtained. Sprayed on the long net, the distribution is not uniform, from the microscopic point of view, drug droplets sprayed on the paper in some places can not be sprayed; from the macro point of view, in order to spray evenly, the nozzle and the nozzle must overlap. The racks are not clean and the maintenance workload is large, which can easily lead to nozzle clogging and limit the amount of application. Although the surface sizing can achieve a high amount of application. Less desirable is that the sheets are re-humidified, which means that additional drying is required, and if the speed of the paper machine remains unchanged, the drying section must be costly.
The new development Hydra-Sizer is a newly developed sizing device that uses curtain coating technology to apply up to 75 kilograms of starch or other auxiliaries per ton of paper at the papermaker's wet web. The suspension is extruded from the slits of the die mounted on the square grid. The starch solution falls a few inches like a full screen curtain onto the wet pulp. Starch is combined with wet paper stock and retained. In order to maintain the dryness at the roller, it is necessary to have some auxiliary vacuum boxes and flat vacuum boxes. However, the dryness of the web in the press section can be guaranteed without the need for additional drying cylinders.
Hydra-Sizer System The Hydra-Sizer system consists of a special set of die heads, adjustable brackets, receiving trays and additive supply systems.
The inside of the die is designed to create a flush flow structure to suspend the starch or other suspension and to avoid clumping and plugging of the die. The liquid enters from one end and is fed from the other end. The die can be opened and cleaned with an electric device. The width of the die must be greater than the net width of the roll, so that the excess auxiliaries can be recovered at the wet roller pit. The die can be attached to the edger at any width to minimize circulation. The die is above the catch plate. After starting, the curtain flows back until a uniform full curtain is formed. The die is then moved onto the web and the production process begins. The height of the die can be controlled by the electric jack to control the descent speed of the curtain. The die head is integrally connected with the walking platform. The position of the die can be determined along the direction of the long web to adapt to the change of the concentration of the application agent.
The die feed system is pre-wired with a good tube cloth and is mounted on the bottom rail. All controls are located on the track. The system has a small tank with a stirrer to keep the aid suspended. The suspension is pumped through a set of filters that can be purified in high-speed flow, followed by an air separator, heat exchanger, and the last filter installed in front of the die. The last filter ensures that lumps formed after the initial filter do not enter the die. The last filter does not need to be cleaned unless it is during flushing. All pipes behind the filter are specially designed to prevent briquettes from entering. The air separator is a patented Coating Air Separation system. This system is capable of separating small air bubbles. The paint air separator itself has recently been developed to minimize the flow required to form curtains on the die. This allows the curtain technology to apply minimal amounts of water to the paper, avoiding lower sheet dryness. A heat exchanger is provided; the suspension can be heated to 65 degrees Celsius to increase the drainage of the net, which is heated with water at 90 degrees Celsius to ensure no spots are present.
The Hydra-Sizer test To date, the first objective of the test has been to add starch to waste paper made of corrugating medium and linerboard in order to improve its strength properties. The test was conducted on a fully equipped pilot tester, which produced a variety of papers at the official production speed, and also tested on two industrially produced paper machines, most of which installed a 1-meter-wide die on the edge of the paper. Head to test. A full width die was tested.
The test was carried out using a layer of paper and two layers of paper, using only a long web, a long web, and a wet top of a top net former. Experiment with different types of starch. The best result is simple, inexpensive uncooked corn starch. Starch is added below the expansion humidity. Starch is retained on the paper and cooked in the dry section, resulting in a retention rate of 85%. The location of the starch on the screen can be from close to the headbox to near the roll. Through experiments, it was found that the paper sheet thickness affects the distribution of dryness of paper sheets on the web, and the dryness distribution can be controlled. Tests have shown that the pressing section and the drying section are not contaminated.
The results of standard tests for the production of 127 g/m2 of corrugated medium paper using mixed waste paper and OCC are shown in Tables 1 and 2. The ratio of mixed waste paper to OCC is 50:50. When the amount of lower auxiliaries is 32 kg per ton of paper, the transverse short-pitch compressive strength (CD STF1) of corrugated medium paper is increased by 10%. Concora test of corrugated medium paper has flat compressive strength. (CMT) increased by 25%. The relatively weak ratio is 80:20 ratio of mixed waste paper to OCC and 45 kg per ton of paper. The CDSTFI is increased by 20% and the CMT is increased by 30%. The results shown in Table 2 are two corrugated cores. Paper is made with 100% OCC; the amount of auxiliaries added is 50 kg per ton of paper. The 127 g/m2 and 205 g/m2 CMT and the corrugated paper crush test (CFC) both increased 28-29%.
Conclusion The application of starch by this new technology can reach the application rate that could only be achieved with the size press in the past. It provides significantly uniform sizing and can be controlled by the thickness of the paper, resulting in high retention. In wrapping paper, it can increase the strength by 25-30%, and it also loses the drying ability, making it an ideal solution for the transformation of existing paper machines. This technique is also helpful for the application of other additives such as pigments and fillers, internal sizing agents, and the like. It uses starch sizing and can be extended to other varieties, such as newsprint and high-grade cultural papers, to reduce lint. The first production device is being manufactured and is planned to be installed in the fall of 1997 to produce packaging paper.
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