The Valmet blower concept has proven to be a reliable means of increasing the productivity and efficiency of paper and board machines. Its main idea is to improve the operating performance of paper machines by means of air treatment techniques. Valmet's blow box features a wonderful use of the coanda effect. That is, the high-speed airflow along the surface of the object can be attached to the surface at the corners. There is no mechanical contact between the blow box and the felt or fabric, but the airflow is very uniform. According to the different arrangements of the drying section, the following different types of blower boxes are recommended.
1. Press Nip Blow Box
The press nip blow boxes are installed before the separate press nips to support the sheet and prevent damage to the felt and the rollers.
2, Pres Run Blow Box (PreSS Run Blow Box)
The pressurizing blower box is installed between the press section and the dryer section to support the sheet so as to minimize the free traction section of the most dangerous area during the transfer of the sheet from the press section to the dryer section.
3, Uno Run Blow Box (Uno Run Blow Box)
Uno Run blow boxes are installed between the lower dryers in the dryer section of the dryer to prevent sheets from leaving the dryer.
4, Sym Run HS Blow Box (Sym Run HS Blow Box)
Sym Run HS blow boxes are specially developed for high-speed paper machines with a speed of over 1000 m/min. For such a high speed paper machine, the running properties of the sheets need to be controlled at two locations where the sheets run up and down. This concept provides good running performance due to the formation of negative pressure throughout the entire pocket area of ​​the grooved roller or vacuum roll. In addition, the amount of air drawn by the vacuum roll is also reduced, so that the total energy consumption can be reduced.
5, Uno Run Ventilator
The Uno Run ventilation box is used to ventilate the bag area of ​​the single dryer section and improve the running performance.
6, Twin Run Blow Box (Twin Run Blow Box)
Twin Run blow boxes are installed in the double dryer group of the high speed paper machine to support the sheets so as to reduce the flutter of the sheets and to ventilate the bag area.
7. UniflOW Pocket Ventilator
Uniflow bag ventilators are used for the double dryer group of high speed paper machines. The ventilation box can increase the amount of hot air in the bag area to improve the drying efficiency, and can help control the horizontal humidity distribution of the bag area.
8. Uniflow B Pocket Venilator
UniflOW B bag ventilation box is suitable for board machines that require high drying capacity.
The Valmet blower concept is a proven technology that has been used on more than a thousand paper and board machines worldwide. These paper mills benefited from this technology.
Press nip blow boxes Modern paper machines often add a separate press before the sheet enters the dryer section. Air is drawn through and along the felt in the nip. Causes separation of the paper sheet from the felt. At worst, it may cause damage to the felt or the roller. The negative pressure generated by the press nip blow box prevents the sheet from fluttering prior to the press nip and maintains good contact between the sheet and the press felt.
The Tail Run Blow Box is operated in the area after the vacuum series to ensure reliable threading. The blow box uses compressed air to maintain good contact between the tail and the press felt.
Squeezing Running the blow box The sheet of paper on the traditional paper machine between the press section and the dryer section is not supported, but the sheet is very weak in this area and is often affected by unstable airflow. The weak sheet is also stretched, which forces the paper machine to operate at a low speed to avoid fluttering and wrinkling of the sheet. Higher sheet tension can cause lower quality and even frequent paper breaks.
To solve this problem, first, the dry web on the first dryer should be brought close to the center roll so that the unsupported length of the sheet can be as short as possible. Use the press to run the blow box to ensure that the sheet rests on the dryer. The blow box generates a very effective negative pressure between the sheet and the dry web, but there is no mechanical contact between the blow box and the dryer, thus ensuring that the dry web is free of any wear.
The air suction produced by the dry web is eliminated by using the best nozzle shape and the correct guide roller position. Using the press to run the blow box reduces the length of the sheet, reduces the number of breaks, and greatly improves the running performance. Valmet's press operation concept is suitable for different types of press configurations, such as 3 nip presses, independent presses, shoe presses, and the like.
Squeeze running blow boxes have achieved good results on low basis paper machines and board machines.
Uno Run blow boxes in the dryer section of the dryer fabric. When the sheet leaves a dryer and runs to another dryer, the built-in pressure is generated due to the air flow generated by the high speed, thereby separating the sheet from the dryer. Additional undesirable effects are the adhesion between the sheet and the smooth dryer surface at the upper nip, and the centrifugal force generated at the lower row of dryers. These factors result in the separation of the sheet from the dry web, causing runnability problems - wrinkling or web breaks.
Uno Run blow boxes are installed between the upper and lower dryers in the dryer section of the dryer fabric to prevent separation of the sheets from the dryer fabric. Because such a blow box can generate a negative pressure to eliminate the pressure in the nip between the dryer cylinder and the dryer web, separation of the paper sheet from the dryer web can be prevented. On modern paper machines, it is common to use grooved lower rows of dryers or drilled vacuum rolls to further increase the negative pressure effect.
The Sym Run RS blow box provides good running performance thanks to the Sym Run HS blow box concept which creates negative pressure in the entire bag area above the vacuum roll. In addition, the vacuum roller can be reduced in the amount of exhaust gas, so that the total energy consumption can be reduced. This concept utilizes specially designed blow nozzles on both sides of the bag area, creating a negative pressure between the blow box and the dryer. This kind of blow box is not in contact with the dry net and has no mechanical seal, so it will not wear dry nets. The concept applies to all forms of drying in a single dry run.
Uno Run Ventilation Box Ventilation Boxes are used in the bag section between the dryers in the dryer section of a single dryer dryer. This ventilator improves ventilation in this area, increases the drying capacity, and can result in a more even pressure condition within the bag area. And improve operating performance.
Valmet Ventilation Box Family For the ventilation of the double felt dry bag area, Valmet developed a complete family of bag ventilation boxes. According to the paper machine speed and paper type and choose the right concept.
The Twin Run blow box The Twin Run blow box generates a negative pressure to maintain good contact between the sheet and the dry web while allowing the bag area to ventilate. The main idea of ​​this ventilated box is to support the sheets after the dryer as long as possible. The installation of the felt roll is not centered, but biased towards the wet end. Thus, the unsupported free traction section of the sheet can be shortened by 30-50%.
The Twin Run blow box not only improves the running performance due to the increased stability of the sheet, but also makes the evaporation and the removal of moist air more effective because the air flow into the bag area can be controlled. The moisture distribution in the Twin Run dryer bag area is uniform, which results in a uniform lateral moisture distribution of the paper.
The TWin Run concept is most effective in the first twin dryer group, but it also applies to the entire twin dryer section of a high speed paper machine.
Unifow bag ventilation box Valmet UniflOW blow box can be installed throughout the dryer section. Good pocket ventilation and axial controllability, as well as increased air flow due to roller rolling, are typical features of this ventilated box. If necessary, the Uniflow Ventilation Box can be fitted with adjustable sections on both sides to control the air distribution throughout.
Unifiow B bag ventilation box Uniflow B bag ventilation box is designed for the board machine. Its characteristic is that the flow of hot air is large, the pressure is low, and the distribution of hot air is very uniform. The new air distribution system is used. The Uniflow B bag ventilation box is equipped with local airflow adjustment mechanisms on both sides of the paper sheet, which can control the amount of air blowing on both sides of the paper sheet.
The air supply system of the blow box To achieve reliable operation of the blow box, it is very important to blow hot air with a sufficient flow rate to the blow box. According to the form of the blow box and the different purposes, the gas supply methods that can be taken are as follows:
l. For the press nip blow box and the press blow box, the papermaking workshop air is usually used.
2. For Uno Run blow boxes, most of the air supply comes from the hood and can also be used in air.
3. For the Twin Run blow box, dry air is usually used. Dry air and mixed air from the hood recirculating air can also be used.
4. For all bag ventilation boxes, dry hot air from the hood air supply system is used. (Weimei De Xi'an Paper Machinery Co., Ltd. Jiang Shifang 710086)
1. Press Nip Blow Box
The press nip blow boxes are installed before the separate press nips to support the sheet and prevent damage to the felt and the rollers.
2, Pres Run Blow Box (PreSS Run Blow Box)
The pressurizing blower box is installed between the press section and the dryer section to support the sheet so as to minimize the free traction section of the most dangerous area during the transfer of the sheet from the press section to the dryer section.
3, Uno Run Blow Box (Uno Run Blow Box)
Uno Run blow boxes are installed between the lower dryers in the dryer section of the dryer to prevent sheets from leaving the dryer.
4, Sym Run HS Blow Box (Sym Run HS Blow Box)
Sym Run HS blow boxes are specially developed for high-speed paper machines with a speed of over 1000 m/min. For such a high speed paper machine, the running properties of the sheets need to be controlled at two locations where the sheets run up and down. This concept provides good running performance due to the formation of negative pressure throughout the entire pocket area of ​​the grooved roller or vacuum roll. In addition, the amount of air drawn by the vacuum roll is also reduced, so that the total energy consumption can be reduced.
5, Uno Run Ventilator
The Uno Run ventilation box is used to ventilate the bag area of ​​the single dryer section and improve the running performance.
6, Twin Run Blow Box (Twin Run Blow Box)
Twin Run blow boxes are installed in the double dryer group of the high speed paper machine to support the sheets so as to reduce the flutter of the sheets and to ventilate the bag area.
7. UniflOW Pocket Ventilator
Uniflow bag ventilators are used for the double dryer group of high speed paper machines. The ventilation box can increase the amount of hot air in the bag area to improve the drying efficiency, and can help control the horizontal humidity distribution of the bag area.
8. Uniflow B Pocket Venilator
UniflOW B bag ventilation box is suitable for board machines that require high drying capacity.
The Valmet blower concept is a proven technology that has been used on more than a thousand paper and board machines worldwide. These paper mills benefited from this technology.
Press nip blow boxes Modern paper machines often add a separate press before the sheet enters the dryer section. Air is drawn through and along the felt in the nip. Causes separation of the paper sheet from the felt. At worst, it may cause damage to the felt or the roller. The negative pressure generated by the press nip blow box prevents the sheet from fluttering prior to the press nip and maintains good contact between the sheet and the press felt.
The Tail Run Blow Box is operated in the area after the vacuum series to ensure reliable threading. The blow box uses compressed air to maintain good contact between the tail and the press felt.
Squeezing Running the blow box The sheet of paper on the traditional paper machine between the press section and the dryer section is not supported, but the sheet is very weak in this area and is often affected by unstable airflow. The weak sheet is also stretched, which forces the paper machine to operate at a low speed to avoid fluttering and wrinkling of the sheet. Higher sheet tension can cause lower quality and even frequent paper breaks.
To solve this problem, first, the dry web on the first dryer should be brought close to the center roll so that the unsupported length of the sheet can be as short as possible. Use the press to run the blow box to ensure that the sheet rests on the dryer. The blow box generates a very effective negative pressure between the sheet and the dry web, but there is no mechanical contact between the blow box and the dryer, thus ensuring that the dry web is free of any wear.
The air suction produced by the dry web is eliminated by using the best nozzle shape and the correct guide roller position. Using the press to run the blow box reduces the length of the sheet, reduces the number of breaks, and greatly improves the running performance. Valmet's press operation concept is suitable for different types of press configurations, such as 3 nip presses, independent presses, shoe presses, and the like.
Squeeze running blow boxes have achieved good results on low basis paper machines and board machines.
Uno Run blow boxes in the dryer section of the dryer fabric. When the sheet leaves a dryer and runs to another dryer, the built-in pressure is generated due to the air flow generated by the high speed, thereby separating the sheet from the dryer. Additional undesirable effects are the adhesion between the sheet and the smooth dryer surface at the upper nip, and the centrifugal force generated at the lower row of dryers. These factors result in the separation of the sheet from the dry web, causing runnability problems - wrinkling or web breaks.
Uno Run blow boxes are installed between the upper and lower dryers in the dryer section of the dryer fabric to prevent separation of the sheets from the dryer fabric. Because such a blow box can generate a negative pressure to eliminate the pressure in the nip between the dryer cylinder and the dryer web, separation of the paper sheet from the dryer web can be prevented. On modern paper machines, it is common to use grooved lower rows of dryers or drilled vacuum rolls to further increase the negative pressure effect.
The Sym Run RS blow box provides good running performance thanks to the Sym Run HS blow box concept which creates negative pressure in the entire bag area above the vacuum roll. In addition, the vacuum roller can be reduced in the amount of exhaust gas, so that the total energy consumption can be reduced. This concept utilizes specially designed blow nozzles on both sides of the bag area, creating a negative pressure between the blow box and the dryer. This kind of blow box is not in contact with the dry net and has no mechanical seal, so it will not wear dry nets. The concept applies to all forms of drying in a single dry run.
Uno Run Ventilation Box Ventilation Boxes are used in the bag section between the dryers in the dryer section of a single dryer dryer. This ventilator improves ventilation in this area, increases the drying capacity, and can result in a more even pressure condition within the bag area. And improve operating performance.
Valmet Ventilation Box Family For the ventilation of the double felt dry bag area, Valmet developed a complete family of bag ventilation boxes. According to the paper machine speed and paper type and choose the right concept.
The Twin Run blow box The Twin Run blow box generates a negative pressure to maintain good contact between the sheet and the dry web while allowing the bag area to ventilate. The main idea of ​​this ventilated box is to support the sheets after the dryer as long as possible. The installation of the felt roll is not centered, but biased towards the wet end. Thus, the unsupported free traction section of the sheet can be shortened by 30-50%.
The Twin Run blow box not only improves the running performance due to the increased stability of the sheet, but also makes the evaporation and the removal of moist air more effective because the air flow into the bag area can be controlled. The moisture distribution in the Twin Run dryer bag area is uniform, which results in a uniform lateral moisture distribution of the paper.
The TWin Run concept is most effective in the first twin dryer group, but it also applies to the entire twin dryer section of a high speed paper machine.
Unifow bag ventilation box Valmet UniflOW blow box can be installed throughout the dryer section. Good pocket ventilation and axial controllability, as well as increased air flow due to roller rolling, are typical features of this ventilated box. If necessary, the Uniflow Ventilation Box can be fitted with adjustable sections on both sides to control the air distribution throughout.
Unifiow B bag ventilation box Uniflow B bag ventilation box is designed for the board machine. Its characteristic is that the flow of hot air is large, the pressure is low, and the distribution of hot air is very uniform. The new air distribution system is used. The Uniflow B bag ventilation box is equipped with local airflow adjustment mechanisms on both sides of the paper sheet, which can control the amount of air blowing on both sides of the paper sheet.
The air supply system of the blow box To achieve reliable operation of the blow box, it is very important to blow hot air with a sufficient flow rate to the blow box. According to the form of the blow box and the different purposes, the gas supply methods that can be taken are as follows:
l. For the press nip blow box and the press blow box, the papermaking workshop air is usually used.
2. For Uno Run blow boxes, most of the air supply comes from the hood and can also be used in air.
3. For the Twin Run blow box, dry air is usually used. Dry air and mixed air from the hood recirculating air can also be used.
4. For all bag ventilation boxes, dry hot air from the hood air supply system is used. (Weimei De Xi'an Paper Machinery Co., Ltd. Jiang Shifang 710086)
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