The paper industry is a highly-invested industry. Large-scale paper machines, coating machines, and finishing equipment basically rely on imports, and almost all of them are imported. The country spends a lot of foreign exchange each year to purchase papermaking equipment. In order to change this situation, the state has introduced some policies to encourage domestic enterprises to carry out technological research on papermaking equipment and try to increase the localization rate of large-scale papermaking equipment. For many years, Changsha Zhengda Heater Factory has been conducting fruitful research in the field of papermaking ventilation, and has achieved success in the research, production, and use of all major papermaking ventilation equipment. They mainly include a dry section airtight hood, a blow box with various functions in the air hood, a hood air exhaust heat recovery unit, a paper machine wet end exhaust air and related equipment, a paper edge transportation equipment, a workshop unit ventilation unit, and the like. .
First, the dry part of the closed hood dry section closed hood in the paper machine ventilation system is the highest value, it is a very important equipment in papermaking equipment. The design of the airtight hood must meet the following functions:
1. Provide a closed high-temperature environment to facilitate the drying of paper sheets and reduce the amount of exhaust air, and improve the heat recovery effect of air hood exhaust. The most popular design in the world is that the dry bulb temperature in the hood is 80-85°C and the dew point temperature is 58-62°C.
2. The airtight hood must facilitate the monitoring, operation, and maintenance of the paper machine's operating conditions. It must be easy to pull and change rolls.
3. The high temperature and humidity inside the airtight hood make it particularly easy to cause condensation. The design of the air hood must completely prevent the condensation of the top cover of the air hood.
4. As much as possible, the gas in the hood is not released to the workshop.
5. The airtight hood should be able to adjust the machine's vertical air flow to ensure that the required amount of air is exhausted from each dry area of ​​the paper web.
6. Closed hoods should fully consider lighting, firefighting and other facilities to meet various needs.
7. The airtight hood covers a large area in the papermaking workshop. Therefore, the appearance of the hood must be beautiful and durable.
In order to close the hood to meet the above-mentioned functions, we have extensively absorbed the strengths of various types of hoods in the world and designed our hoods carefully, meticulously and thoughtfully. 1. Our airtight hood is a modularly designed closed structure, in order to enable the dry bulb temperature within the hood to be 80-85°C, the dew point temperature is 58-62°C, the high temperature and high humidity gas does not cause condensation, water drops, and the hood of the air hood. The end plate and the side plate are all sandwich structures. The inner plate and the outer plate are rust-proof aluminum plates, and the middle is a rigid centrifugal glass wool plate. A "labyrinth" connection is used between the board and the board to eliminate the "cold bridge" to the maximum extent possible. The panel can be sinusoidal corrugated plate or trapezoidal corrugated plate. The appearance is very beautiful and can be selected according to the user's requirements.
2. The airtight hood has a long electric lift gate on the operation side. A lift gate is 2.5 meters high and 6 meters long. There is a long insulated glass window on the lift door. The transmission test has a sliding door, and the sliding door is also equipped with a thermal glass observation window. Inside the hood, the operation of the paper machine is clear at a glance. The lifting door is provided with a break signal linkage device. Once the paper break lifting door is automatically lifted, lifting of the lifting door can also be manually operated on the console. A manual door for replacing the roller is opened on the operation side panel. In order to facilitate the change of the roller, a manual hoist in the longitudinal direction and the horizontal direction is provided in the hood. The lifting door body is provided with a broken rope protection device. The lifting door body is safe and reliable, and all operations are very convenient.
3. In order to make the hood open when the lift gate is open, the hot humid gas in the hood does not overflow to pollute the workshop environment. At the same time, the cold air in the workshop does not allow a large amount of cold air to enter the hood to affect the high temperature environment inside the hood. A "zero" control device is provided on the hood. “Zero†is located at the upper edge of the lift gate; at this position, gas inside and outside the hood does not flow because the pressure difference is zero. Below "zero", air flows from the hood to the hood. Above "zero", air flows from the hood to the outside of the hood. Therefore, in order to prevent the gas in the hood from flowing out, the hood above the door is lifted. Body, sealing should be very good. The level of "Zero" depends on the amount of air supplied by the hood and the amount of exhaust. The amount of exhaust is controlled by detecting the moisture content in the exhaust. "Zero" is adjusted by controlling the amount of hot air sent to the hood through a "zero" detection device mounted on the hood.
4. The closed air hood is equipped with a complete low-voltage lighting system and an automatic fire extinguishing system to meet the fire and lighting requirements.
In summary, we provide users with a high-quality product with excellent performance, complete functions, simple operation, and beautiful appearance.
Second, the paper machine running a variety of blow boxes in the modern paper machine, due to the use of airtight hoods, must use low-temperature high-temperature air to balance the air exhaust hood, in order to enable the paper to run smoothly at high speed, and in order to improve The transverse moisture distribution of the paper web is provided with various blower boxes with different functions depending on the type of paper and the speed of the vehicle.
1. Traditional bag blow box (ventilator)
In the dryer section consisting of a double row dryer and a double dryer, a relatively closed area is formed by the upper dryer, the web, and the lower dryer. This area is commonly called the "bag area." The exchange of air in the bag area with the outside world is very slow. The drying of the paper web will be greatly affected. The moisture content of the banner of the paper web is also very uneven. The paper web has less moisture, and the middle moisture is more. In order to solve this problem, the common practice in the world is to set up blow boxes at the Shanggan Net. The blow box nozzle sends high-speed hot air to the bag area to replace the saturated moist air in the bag area with relatively dry hot air, thereby improving the drying efficiency of the drying section and improving the moisture distribution of the web banner. This baghouse blow box has been widely used in new paper machines and can play a significant role in the transformation of old paper machines. Depending on the type of paper, the nozzles for this pocket fan have different forms to meet different requirements. The zone ventilator is provided with a zone air volume adjustment device in the transverse direction of the paper machine, which can conveniently adjust the air volume of each zone on the drive side of the paper machine so as to achieve uniform distribution of the transverse air volume of the paper machine.
2. Steady Paper Ventilators For high-speed paper machines, the dryer section is usually arranged in a single row of dryer dryers. The world's largest paper machine manufacturers have designed stable paper blow boxes through extensive research. Install a steady paper blow box in the area enclosed by the lower cylinder (or vacuum roller) and the dryer fabric. Its principle is to blow out the air flow from the stable paper blowing box at high speed, and at the same time blowing the air flow at the end of the steady paper blowing box to form an air seal. Due to the induction of the air flow, a negative pressure is formed between the steady paper blowing box and the dryer. Press area. The negative pressure adsorbs the paper web tightly on the dry web, thereby avoiding jitter, squeezing and web break of the paper web, and solves the problem of the high-speed paper machine in operation. We have conducted a lot of research on various blow boxes, and now we have mastered this technology. With the above two types of blow boxes, the problems of drying, running stability, and lateral moisture distribution in the dryer section can be solved.
Third, the drying part of the exhaust hood exhaust heat recovery The air temperature of the closed hood is generally about 82 °C, moisture content of about 0.16kgH20/kg.da, each kilogram of exhaust air is 507kJ, for an annual output For a paper machine with a capacity of 100,000 tons, the exhaust volume of the airtight hood is about 150,000 kg/h, and the paper opportunities for different types of paper are different. The enthalpy in an hourly exhaust is about 76050000 kJ, which is equivalent to the heat of condensation of 33 tons of steam. The value of heat enthalpy is quite considerable. It is directly drained and the energy is wasted. Due to the use of airtight hoods, the exhaust air temperature and moisture content are both high, which creates the conditions for the heat recovery of the exhaust air.
Finding a good use for recovered heat is the primary issue of heat recovery. For example, in cold regions, manufacturers in the world usually divide the exhaust into three levels for heat recovery. The first stage is air-to-gas heat recovery, the second stage is gas-water heat recovery, and the third stage is air-glycol heat recovery. Other regions may choose primary or secondary heat recovery depending on the climate. The first stage is air-to-gas heat recovery. The exhaust air system is used to preheat the air supply system inside the air hood. This type of heat recovery has the highest utilization value and is used to recover heat throughout the year. It must be set for any closed air hood exhaust. Because of the installation of such a heat recovery device, the investment can be recovered in less than one year. The first-stage air-to-gas heat recovery device adopts a tube heat exchanger. Because it is gas-gas heat exchange, the heat transfer coefficient is small, and the heat recovery is relatively limited. The heat recovered by the first heat recovery device only accounts for the total heat of the exhaust air. %about.
After one-stage heat recovery, the supply air temperature can reach about 60°C, the exhaust air temperature is about 62°C, and the exhaust heat is still high. A second-stage gas-water heat recovery unit can be used to recover heat. The second-stage heat recovery device generally uses exhaust air to heat the process water. The process of washing the blankets requires a large amount of hot water. If steam is used to heat the clean water, a large amount of steam is consumed, and exhaust air can be used to heat this portion of water. . The second stage of heat recovery is gas-water heat recovery, using stainless steel heat exchange tubes, high gas-water heat transfer coefficient, high heat recovery, and is running throughout the year, as long as there is demand, secondary heat recovery investment can generally be Recovered in six months. After the secondary heat recovery device, the water temperature can reach about 45°C, the exhaust air temperature is about 45°C, and the recovered heat accounts for about 20% of the total heat enthalpy of the exhaust. After the secondary heat recovery, the enthalpy of the exhaust is still relatively large, but due to the low temperature, the value of the recovery is not significant. Only the areas with a calculated temperature outside the heating outside the range of -15°C are considered for the third stage heat recovery.
The third stage heat recovery is the heat recovery of gas-ethylene glycol solution. The exhaust air is used to heat about 20% of the ethylene glycol solution to preheat the workshop air. The amount of exhaust air in the papermaking workshop is large. In order to achieve air volume balance in the workshop, a large amount of outdoor fresh air must be added to the workshop. In northern regions, the outdoor air temperature in winter is very low, and heating of this part requires a lot of heat. Therefore, in the cold northern regions, it is absolutely necessary to set up tertiary heat recovery. The amount of heat recovery in the third stage generally accounts for about 25% of the total heat of the exhaust. After the heat recovery in the third stage, it is difficult to recover the heat in the exhaust. The above three heat recovery devices are all equipped with an automatic water jet cleaning device to prevent paper hairs from accumulating on the surface of the heat exchanger. Hood heat recovery, in addition to the above purposes, can also be optimized according to the user's situation, so that investment in heat recovery funds recovered in the shortest possible time.
First, the dry part of the closed hood dry section closed hood in the paper machine ventilation system is the highest value, it is a very important equipment in papermaking equipment. The design of the airtight hood must meet the following functions:
1. Provide a closed high-temperature environment to facilitate the drying of paper sheets and reduce the amount of exhaust air, and improve the heat recovery effect of air hood exhaust. The most popular design in the world is that the dry bulb temperature in the hood is 80-85°C and the dew point temperature is 58-62°C.
2. The airtight hood must facilitate the monitoring, operation, and maintenance of the paper machine's operating conditions. It must be easy to pull and change rolls.
3. The high temperature and humidity inside the airtight hood make it particularly easy to cause condensation. The design of the air hood must completely prevent the condensation of the top cover of the air hood.
4. As much as possible, the gas in the hood is not released to the workshop.
5. The airtight hood should be able to adjust the machine's vertical air flow to ensure that the required amount of air is exhausted from each dry area of ​​the paper web.
6. Closed hoods should fully consider lighting, firefighting and other facilities to meet various needs.
7. The airtight hood covers a large area in the papermaking workshop. Therefore, the appearance of the hood must be beautiful and durable.
In order to close the hood to meet the above-mentioned functions, we have extensively absorbed the strengths of various types of hoods in the world and designed our hoods carefully, meticulously and thoughtfully. 1. Our airtight hood is a modularly designed closed structure, in order to enable the dry bulb temperature within the hood to be 80-85°C, the dew point temperature is 58-62°C, the high temperature and high humidity gas does not cause condensation, water drops, and the hood of the air hood. The end plate and the side plate are all sandwich structures. The inner plate and the outer plate are rust-proof aluminum plates, and the middle is a rigid centrifugal glass wool plate. A "labyrinth" connection is used between the board and the board to eliminate the "cold bridge" to the maximum extent possible. The panel can be sinusoidal corrugated plate or trapezoidal corrugated plate. The appearance is very beautiful and can be selected according to the user's requirements.
2. The airtight hood has a long electric lift gate on the operation side. A lift gate is 2.5 meters high and 6 meters long. There is a long insulated glass window on the lift door. The transmission test has a sliding door, and the sliding door is also equipped with a thermal glass observation window. Inside the hood, the operation of the paper machine is clear at a glance. The lifting door is provided with a break signal linkage device. Once the paper break lifting door is automatically lifted, lifting of the lifting door can also be manually operated on the console. A manual door for replacing the roller is opened on the operation side panel. In order to facilitate the change of the roller, a manual hoist in the longitudinal direction and the horizontal direction is provided in the hood. The lifting door body is provided with a broken rope protection device. The lifting door body is safe and reliable, and all operations are very convenient.
3. In order to make the hood open when the lift gate is open, the hot humid gas in the hood does not overflow to pollute the workshop environment. At the same time, the cold air in the workshop does not allow a large amount of cold air to enter the hood to affect the high temperature environment inside the hood. A "zero" control device is provided on the hood. “Zero†is located at the upper edge of the lift gate; at this position, gas inside and outside the hood does not flow because the pressure difference is zero. Below "zero", air flows from the hood to the hood. Above "zero", air flows from the hood to the outside of the hood. Therefore, in order to prevent the gas in the hood from flowing out, the hood above the door is lifted. Body, sealing should be very good. The level of "Zero" depends on the amount of air supplied by the hood and the amount of exhaust. The amount of exhaust is controlled by detecting the moisture content in the exhaust. "Zero" is adjusted by controlling the amount of hot air sent to the hood through a "zero" detection device mounted on the hood.
4. The closed air hood is equipped with a complete low-voltage lighting system and an automatic fire extinguishing system to meet the fire and lighting requirements.
In summary, we provide users with a high-quality product with excellent performance, complete functions, simple operation, and beautiful appearance.
Second, the paper machine running a variety of blow boxes in the modern paper machine, due to the use of airtight hoods, must use low-temperature high-temperature air to balance the air exhaust hood, in order to enable the paper to run smoothly at high speed, and in order to improve The transverse moisture distribution of the paper web is provided with various blower boxes with different functions depending on the type of paper and the speed of the vehicle.
1. Traditional bag blow box (ventilator)
In the dryer section consisting of a double row dryer and a double dryer, a relatively closed area is formed by the upper dryer, the web, and the lower dryer. This area is commonly called the "bag area." The exchange of air in the bag area with the outside world is very slow. The drying of the paper web will be greatly affected. The moisture content of the banner of the paper web is also very uneven. The paper web has less moisture, and the middle moisture is more. In order to solve this problem, the common practice in the world is to set up blow boxes at the Shanggan Net. The blow box nozzle sends high-speed hot air to the bag area to replace the saturated moist air in the bag area with relatively dry hot air, thereby improving the drying efficiency of the drying section and improving the moisture distribution of the web banner. This baghouse blow box has been widely used in new paper machines and can play a significant role in the transformation of old paper machines. Depending on the type of paper, the nozzles for this pocket fan have different forms to meet different requirements. The zone ventilator is provided with a zone air volume adjustment device in the transverse direction of the paper machine, which can conveniently adjust the air volume of each zone on the drive side of the paper machine so as to achieve uniform distribution of the transverse air volume of the paper machine.
2. Steady Paper Ventilators For high-speed paper machines, the dryer section is usually arranged in a single row of dryer dryers. The world's largest paper machine manufacturers have designed stable paper blow boxes through extensive research. Install a steady paper blow box in the area enclosed by the lower cylinder (or vacuum roller) and the dryer fabric. Its principle is to blow out the air flow from the stable paper blowing box at high speed, and at the same time blowing the air flow at the end of the steady paper blowing box to form an air seal. Due to the induction of the air flow, a negative pressure is formed between the steady paper blowing box and the dryer. Press area. The negative pressure adsorbs the paper web tightly on the dry web, thereby avoiding jitter, squeezing and web break of the paper web, and solves the problem of the high-speed paper machine in operation. We have conducted a lot of research on various blow boxes, and now we have mastered this technology. With the above two types of blow boxes, the problems of drying, running stability, and lateral moisture distribution in the dryer section can be solved.
Third, the drying part of the exhaust hood exhaust heat recovery The air temperature of the closed hood is generally about 82 °C, moisture content of about 0.16kgH20/kg.da, each kilogram of exhaust air is 507kJ, for an annual output For a paper machine with a capacity of 100,000 tons, the exhaust volume of the airtight hood is about 150,000 kg/h, and the paper opportunities for different types of paper are different. The enthalpy in an hourly exhaust is about 76050000 kJ, which is equivalent to the heat of condensation of 33 tons of steam. The value of heat enthalpy is quite considerable. It is directly drained and the energy is wasted. Due to the use of airtight hoods, the exhaust air temperature and moisture content are both high, which creates the conditions for the heat recovery of the exhaust air.
Finding a good use for recovered heat is the primary issue of heat recovery. For example, in cold regions, manufacturers in the world usually divide the exhaust into three levels for heat recovery. The first stage is air-to-gas heat recovery, the second stage is gas-water heat recovery, and the third stage is air-glycol heat recovery. Other regions may choose primary or secondary heat recovery depending on the climate. The first stage is air-to-gas heat recovery. The exhaust air system is used to preheat the air supply system inside the air hood. This type of heat recovery has the highest utilization value and is used to recover heat throughout the year. It must be set for any closed air hood exhaust. Because of the installation of such a heat recovery device, the investment can be recovered in less than one year. The first-stage air-to-gas heat recovery device adopts a tube heat exchanger. Because it is gas-gas heat exchange, the heat transfer coefficient is small, and the heat recovery is relatively limited. The heat recovered by the first heat recovery device only accounts for the total heat of the exhaust air. %about.
After one-stage heat recovery, the supply air temperature can reach about 60°C, the exhaust air temperature is about 62°C, and the exhaust heat is still high. A second-stage gas-water heat recovery unit can be used to recover heat. The second-stage heat recovery device generally uses exhaust air to heat the process water. The process of washing the blankets requires a large amount of hot water. If steam is used to heat the clean water, a large amount of steam is consumed, and exhaust air can be used to heat this portion of water. . The second stage of heat recovery is gas-water heat recovery, using stainless steel heat exchange tubes, high gas-water heat transfer coefficient, high heat recovery, and is running throughout the year, as long as there is demand, secondary heat recovery investment can generally be Recovered in six months. After the secondary heat recovery device, the water temperature can reach about 45°C, the exhaust air temperature is about 45°C, and the recovered heat accounts for about 20% of the total heat enthalpy of the exhaust. After the secondary heat recovery, the enthalpy of the exhaust is still relatively large, but due to the low temperature, the value of the recovery is not significant. Only the areas with a calculated temperature outside the heating outside the range of -15°C are considered for the third stage heat recovery.
The third stage heat recovery is the heat recovery of gas-ethylene glycol solution. The exhaust air is used to heat about 20% of the ethylene glycol solution to preheat the workshop air. The amount of exhaust air in the papermaking workshop is large. In order to achieve air volume balance in the workshop, a large amount of outdoor fresh air must be added to the workshop. In northern regions, the outdoor air temperature in winter is very low, and heating of this part requires a lot of heat. Therefore, in the cold northern regions, it is absolutely necessary to set up tertiary heat recovery. The amount of heat recovery in the third stage generally accounts for about 25% of the total heat of the exhaust. After the heat recovery in the third stage, it is difficult to recover the heat in the exhaust. The above three heat recovery devices are all equipped with an automatic water jet cleaning device to prevent paper hairs from accumulating on the surface of the heat exchanger. Hood heat recovery, in addition to the above purposes, can also be optimized according to the user's situation, so that investment in heat recovery funds recovered in the shortest possible time.
Sanjin Plastic Industry Co., Ltd. , http://www.sdmakeuppackaging.com