A transverse drawing heat exhaust multi-energy-saving treatment process for bidirectional film drawing production

Abstract

The application discloses a kind of transverse drawing hot exhaust multiple energy-saving treatment processes for bidirectional film production, including heat exchanger, spraying system, demister and the like components;The system of the application can clean and cool the hot air of the heat setting area of transverse drawing device, under normal working conditions, when outdoor temperature is greater than or equal to 20 DEG C, by adjusting the temperature of spray water and controlling the opening and closing of valve, the purified gas is discharged to atmosphere through V1 valve.In winter working condition and intermediate working condition, by adjusting the temperature of spray water and controlling the opening and closing of valve, part of the gas enters heat exchanger to be heated and then is sent to the return air pipe of heat setting area, and the other part of the gas enters transverse drawing workshop as ambient fresh air supplement.The process can effectively reduce energy consumption, improve the workshop environment, and also effectively treat and reduce the emission of organic impurities, protect the environment.

Description

Technical Field

[0001] This invention relates to the field of hot air energy-saving system technology for biaxially stretched film, specifically to a multi-energy-saving process for transverse stretching hot exhaust in biaxially stretched film production. Background Technology

[0002] Current biaxially oriented film production equipment relies on multiple sets of circulating hot air to control the temperature of the preheating, setting, and cooling zones in the transverse stretching process. Each zone discharges a large amount of hot air at different temperatures, resulting in an overall exhaust temperature exceeding 100°C, especially in the setting zone where the exhaust temperature can exceed 150°C. The discharged hot air contains many organic impurities, particularly from nylon 6 films, which contain a significant amount of soluble organic monomers and oligomers that volatilize into the discharged hot air.

[0003] In the traditional biaxially oriented film production process, hot air exhaust is centrally treated, typically at a temperature of 100-110℃. After preliminary filtration, the exhaust enters an energy-saving heat exchanger to recover some heat, and then is cooled by an aftercooler before entering an environmental treatment device to remove VOD from the exhaust gas. Only exhaust gas meeting emission standards is released into the atmosphere. Typical environmental treatment devices often employ catalytic oxidation or photocatalysis combined with activated carbon adsorption, resulting in large investments, large footprints, and high maintenance costs. The fresh air required for the cross-stretching section is directly drawn from the workshop environment, leading to a significant increase in energy consumption, especially in winter.

[0004] In practical operation, especially in the production of biaxially oriented nylon 6 film, monomers and oligomers contained in the hot air condense and adhere to the equipment surface during cooling, causing filter screen blockage, reduced efficiency due to scaling on the heat exchanger surface, and similar problems with the cooler, such as severe scaling, short service life, and difficulty in cleaning. These problems not only affect energy-saving effects but also reduce production efficiency. Therefore, a transverse stretching hot air exhaust energy-saving treatment system for biaxially oriented film production is proposed. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of hot air emission during the production of biaxially oriented films, especially for nylon 6 films. Traditional methods have many drawbacks, such as high investment costs, large footprint, and high maintenance costs, while failing to effectively address equipment scaling and clogging. This invention's system, through the installation of a spray scrubbing tower and spray pumps, effectively cleans and cools the hot air, preventing scaling and clogging. The treated exhaust air can be returned to the shell side of the heat exchanger as clean, cold air for recirculation. This is particularly beneficial in low-temperature conditions such as winter, effectively reducing energy consumption, improving the workshop environment, and effectively treating and reducing the emission of organic impurities, thus protecting the environment.

[0006] This invention discloses a multi-energy-saving process for heat exhaust in biaxial stretching film production. The process involves a system including a heat exchanger. The heat exchanger tube outlet is sequentially connected to a spray system, a demister, an electrostatic precipitator, a suction fan, and an exhaust stack. The gas extracted by the suction fan is divided into three pipelines: one pipeline, treated and discharged into the atmosphere through the exhaust stack, is controlled by valve V1; another pipeline connects to the shell side of the heat exchanger and then delivers it to the heat-setting area of ​​the biaxial stretching device, controlled by valve V2; the third pipeline delivers it to other areas of the biaxial stretching device through the return air pipeline, controlled by valve V3. An upstream fresh air filter is also installed on the shell side of the heat exchanger, filtering ambient air before delivering it to the shell side, controlled by valve V4. The spray system also includes a valve TV that controls the temperature of the gas after spraying.

[0007] The energy-saving process using the above system can be adjusted according to the requirements of different regions and different product processes. Three operating conditions are listed below:

[0008] Normal operating condition: This operating condition is adopted when the average outdoor ambient temperature is ≥20℃; the spray water temperature is adjusted by fully opening valve T1 to control the gas temperature T1 after spraying to drop appropriately, valves V2 and V3 are closed, and valve V1 is opened to allow the purified gas to be discharged to the atmosphere through valve V1 from the exhaust stack; valve V4 is opened to allow the ambient air to enter the heat exchanger 1 through the shell side of the fresh air filter 7 for heat exchange and temperature rise, and then enter the return air duct of the heat setting area. At this time, all return air passes through the fresh air filter, and the return air power comes entirely from the fan in the heat setting area.

[0009] Winter operating condition: This operating condition is adopted when the average outdoor ambient temperature is ≤5℃; the spray water temperature is adjusted by valve T1 to control the gas temperature T1 after spraying to 20℃, valve V1 is closed, valve V4 is slightly opened to stabilize the return air duct pressure, and the opening of valves V2 and V3 is adjusted so that part of the gas enters heat exchanger 1 through valve V2 for heat exchange and temperature rise, and is then sent to the return air duct of the heat setting area. The other part of the gas is sent to the horizontal drawing workshop through valve V3 as a supplement to the fresh air in other areas of the horizontal drawing workshop.

[0010] Intermediate operating condition: This operating condition is adopted when the average outdoor ambient temperature is between 5℃ and 20℃; the spray water temperature is adjusted by valve T1 to control the gas temperature T1 after spraying to 20-25℃, valve V1 is controlled to limit the air volume discharged into the atmosphere, valve V4 is slightly opened to stabilize the pressure of the return air duct, and the opening of valves V2 and V3 is adjusted so that some gas is discharged into the atmosphere through valve V1 from the exhaust stack, some gas enters the heat exchanger through valve V2 for heat exchange and temperature rise, and is sent into the return air duct of the heat setting area, and the other part of the gas is sent into the horizontal drawing workshop through valve V3 as a supplement to the fresh air in other areas of the horizontal drawing workshop.

[0011] During the cold season, replenishing the horizontal drawing workshop with clean gas at around 20°C after washing not only balances the pressure inside the workshop but also reduces the amount of cold outdoor air entering, thus achieving energy conservation.

[0012] In a further preferred embodiment of the above-described technical solution, the spray system comprises a spray scrubbing tower, spray nozzles, and a spray water pump; the spray scrubbing tower has spray nozzles at its top and spray water at its bottom; a spray water circulation pipeline is provided at the bottom of the spray scrubbing tower, and a spray water pump and a spray water filter are installed on the spray water circulation pipeline to transport the spray water from the bottom of the tower to the spray nozzles; the lower side wall of the spray scrubbing tower is provided with, from high to low, a spray water makeup inlet, other exhaust inlets from other areas of the horizontal pulling device, an exhaust inlet for the shaping area connected to the heat exchanger tubes, and an overflow outlet for the spray water.

[0013] For the technical solution described above, a further preferred embodiment is that the valve TV is configured as follows: a discharge outlet and a water cooler are provided downstream of the spray water filter; the water cooler is equipped with a temperature control valve TV to control the water temperature entering the nozzle; a temperature sensor T1 is provided on the air outlet pipe at the top of the spray scrubbing tower; the temperature control valve TV and the temperature sensor T1 work together to adjust the gas temperature at the air outlet at the top of the spray scrubbing tower by controlling the flow rate of the cold water in the water cooler.

[0014] A further preferred embodiment of the above-described technical solution is that the heat exchanger has a removable filter at the front end of the tube side.

[0015] For the technical solution described above, a further preferred embodiment is that the detachable filter is a drawer-type filter, which is equipped with a detachable multi-layer stainless steel wire mesh, and the thickness of the regularized filler of the multi-layer stainless steel wire mesh is 100-200mm.

[0016] In a further preferred embodiment of the above-described technical solution, the heat exchanger further includes a shaping zone fresh air heat exchange chamber. A shaping zone hot air heat exchange pipeline structure is provided on the outer side of the shaping zone fresh air heat exchange chamber. The shaping zone hot air heat exchange pipeline structure includes a second pipe box and a first pipe box located at the bottom of the shaping zone fresh air heat exchange chamber. A removable filter is provided on the upper part of the first pipe box. A shaping zone hot air inlet is provided on the outer side of the first pipe box and below the removable filter. A first heat exchange tube vertically penetrating the shaping zone fresh air heat exchange chamber is provided on the top of the first pipe box. An upper pipe box is removably provided at the upper end of the shaping zone fresh air heat exchange chamber. A second heat exchange tube vertically penetrating the shaping zone fresh air heat exchange chamber is provided on the top of the second pipe box. A shaping zone hot air outlet is provided in the middle of the outer side of the second pipe box.

[0017] For the technical solution described above, a further preferred embodiment is that the fresh air heat exchange chamber of the shaping area includes a heat exchange shell, and the two ends of the heat exchange shell in the horizontal direction are respectively provided with a shaping area return air inlet (cold air) and a shaping area hot air outlet; the shaping area return air inlet (cold air) is connected to the upstream suction fan through the V2 control of the shaping area return air duct; the shaping area hot air outlet is connected to the heat shaping area of ​​the horizontal pulling device.

[0018] For the technical solution described above, a further preferred embodiment is that the first heat exchange tube is located on the same side as the hot air outlet of the shaping area; the second heat exchange tube is located on the same side as the return air inlet (cold air) of the shaping area; the first heat exchange tube connects the first tube box and the upper tube box; and the second heat exchange tube connects the second tube box and the upper tube box.

[0019] In a further preferred embodiment of the above-described technical solution, the cooled hot air exits from the tube side of the heat exchanger and enters the spray system from the exhaust inlet of the shaping zone on the side wall of the spray system.

[0020] In a further preferred embodiment of the technical solution described above, the air output from other areas of the horizontal pulling device is connected to the side of the spray system through other exhaust pipes.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. Separate Hot Air Filtration: In this system, the hot air exhausted from the heat-setting area of ​​the transverse drawing workshop is filtered separately using a drawer-type filter. This portion of the exhaust air accounts for 20%-30% of the total exhaust volume, while containing 50%-70% of the organic impurities. This targeted filtration method effectively improves filtration efficiency and reduces filtration costs. Separate filtration removes organic impurities from the hot air more efficiently, thereby improving the overall filtration effect and reducing the impact on the entire system.

[0023] 2. This heat exchanger uses a hot air heat exchange pipeline structure in the shaping zone to initially filter hot air containing organic impurities. Hot air containing organic impurities flows through the tube side, while clean cold air flows through the shell side. This extends the service life of the heat exchanger. The upper tube box is removable and can be used as a cleaning surface for the first and second heat exchange tubes, facilitating cleaning and improving heat exchange efficiency, especially for the high-temperature hot air discharged from the shaping zone in the nylon 6 biaxially oriented film production unit. Furthermore, the heat exchanger inlet is equipped with a removable filter. The filter media uses a multi-layer metal wire mesh structure, offering good temperature resistance, large dirt-holding capacity, strong capture ability, and easy cleaning. The upper tube box can be opened as a whole, serving as a cleaning surface for the first and second heat exchange tubes.

[0024] 3. Spray scrubbing cooling method: The exhaust end of the heat exchanger is connected to the spray system, and the exhaust end of the spray system is connected to the demister. Exhaust air from the filtered heat-setting area and other areas is introduced into the spray system. The spray system cools the exhaust air while removing soluble impurities from the gas. This spray scrubbing cooling method dissolves or disperses the washed-off organic impurities in water, which are then sent to a wastewater treatment plant for further processing along with the discharged wastewater. Compared to other gas cooling methods, this method effectively prevents scaling on the inner wall of the cooler.

[0025] 4. Controllable Exhaust Temperature: The exhaust temperature of the spray system can be controlled as needed, allowing the system to meet various operating conditions. This control method also features simple operation, long maintenance cycles, and high impurity removal rate. By controlling the exhaust temperature, the system can better adapt to different production needs and environmental conditions, improving its flexibility and adaptability.

[0026] 5. Multi-stage purification process: The washed, low-temperature gas contains a small amount of insoluble organic particulate matter, which enters the subsequent demister. The demister separates and captures these particles using physical methods. After demistering, the gas enters the electrostatic precipitator, where electrostatic discharge effectively captures these organic particulate matter, ensuring the gas meets emission standards. This multi-stage purification process comprehensively removes various impurities from the gas, ensuring the cleanliness and safety of the emitted gas.

[0027] In summary, this system primarily utilizes principles such as heat recovery, spray cooling, demisting, electrostatic oil removal, and exhaust ventilation. Through the effective operation of each processing stage, comprehensive hot air recovery and recycling are achieved. This not only improves energy utilization and production efficiency but also solves the problems of hot air emissions, equipment scaling, and clogging in traditional biaxially oriented film production processes. Furthermore, the system design also considers environmental protection requirements, effectively reducing the emission of organic impurities through various processing stages, thus protecting the environment. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a heat exhaust system in the prior art;

[0029] Figure 2 This is a schematic diagram of the system of the present invention.

[0030] Figure 3 This is a schematic diagram of the structure of heat exchanger 1.

[0031] In the diagram: 1-Heat exchanger, 2-Spray system, 201-Spray scrubbing tower, 202-Spray head, 203-Spray water pump, 204-Spray water filter, 3-Demister, 4-Electrostatic oil separator, 5-Exhaust fan, 6-Exhaust stack, 7-Fresh air filter.

[0032] 11-Forming zone fresh air heat exchange chamber, 111-Heat exchange shell, 112-Forming zone return air inlet (cold air), 113-Forming zone hot air outlet, 12-Forming zone hot air heat exchange pipeline structure, 121-Second tube box, 122-First tube box, 123-Forming zone hot air inlet, 124-First heat exchange tube, 125-Upper tube box, 126-Second heat exchange tube, 127-Forming zone hot air outlet, 13-Drawer-type filter, 14-Inspection hole. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0034] Figure 1 This is a schematic diagram of a heat exhaust system in existing technology. The environmental protection treatment device shown in the figure is typically compared with other methods such as catalytic oxidation, thermal oxidation, molecular sieve adsorption, activated carbon adsorption, and photocatalysis, which are all uneconomical for the membrane stretching industry.

[0035] Figure 2 The system of this invention is used for exhaust treatment in a horizontal stretching workshop. The horizontal stretching equipment in the workshop typically consists of a preheating zone, a stretching zone, a heat setting zone, a cooling zone, and a buffer zone. Each zone has independent air intake and exhaust. The exhaust air temperature in the heat setting zone is the highest (above 150°C), and its air intake temperature is also required to be the highest. This part of the exhaust air accounts for 20%-30% of the total exhaust air volume, and contains 50%-70% of the total exhaust air volume. This system filters this part of the hot air separately, which can effectively improve the filtration efficiency and reduce the filtration cost.

[0036] Example 1

[0037] This technical solution is a multi-energy-saving process for heat exhaust in biaxial stretching film production. The system includes a heat exchanger 1, a spray system 2, a demister 3, an electrostatic precipitator 4, a suction fan 5, and an exhaust stack 6. The heat exchanger 1 is located at the system inlet and receives hot air exhausted from the heat-setting area of ​​the biaxial stretching device. The hot air enters the system through the tube side of the heat exchanger 1, and the tube side outlet of the heat exchanger 1 is connected to the hot air inlet on the side wall of the spray system 2. The air outlet at the top of the spray system 2 is sequentially connected to the demister 3, the electrostatic precipitator 4, and the suction fan 5. After passing through the suction fan... The air extracted by the machine 5 is divided into three pipelines. One pipeline is discharged into the atmosphere through the exhaust pipe 6 and is controlled by valve V1. The second pipeline is connected to the shell side of the heat exchanger 1 and then transported to the heat setting area of ​​the horizontal stretching device, controlled by valve V2. The third pipeline is transported to other areas of the horizontal stretching device through the horizontal stretching return air pipeline and is controlled by valve V3. A fresh air filter 7 is also installed upstream of the shell side of the heat exchanger, which filters the ambient air and then transports it to the shell side of the heat exchanger 1, controlled by valve V4. The spray system 2 is also equipped with a valve TV that can control the temperature of the gas after spraying.

[0038] The heat exchanger 1 has a removable filter 13 at the front end of the tube side. The removable filter 13 is a drawer-type filter with removable multi-layer stainless steel wire mesh inside. The thickness of the packing material of the multi-layer stainless steel wire mesh is 100-200mm.

[0039] More specifically, the structure of the heat exchanger is as follows: it further includes a shaping zone fresh air heat exchange chamber 11, and a shaping zone hot air heat exchange pipeline structure 12 is provided on the outside of the shaping zone fresh air heat exchange chamber 11. The shaping zone hot air heat exchange pipeline structure 12 includes a second pipe box 121 and a first pipe box 122 located at the bottom of the shaping zone fresh air heat exchange chamber. A removable filter 13 is provided on the upper part of the first pipe box 122. A shaping zone hot air inlet 123 is provided on the outside of the first pipe box 122 and below the removable filter. A first heat exchange tube 124 that vertically penetrates the shaping zone fresh air heat exchange chamber 11 is provided on the top of the first pipe box 122. An upper pipe box 125 is detachably provided at the upper end of the shaping zone fresh air heat exchange chamber 11. A second heat exchange tube 126 is vertically installed at the top of the tube box 121, penetrating the fresh air heat exchange chamber 11 of the shaping zone. A hot air outlet 127 for the shaping zone is installed in the middle of the outer side of the second tube box 121. The fresh air heat exchange chamber 11 of the shaping zone includes a heat exchange shell 111. The two ends of the heat exchange shell 111 in the horizontal direction are respectively provided with a cold air return air inlet 112 for the shaping zone and a hot air outlet 113 for the shaping zone. The first heat exchange tube 124 is located on the same side as the hot air outlet 113 for the shaping zone. The second heat exchange tube 126 is located on the same side as the cold air return air inlet 112 for the shaping zone. The first heat exchange tube 124 connects the first tube box 122 and the upper tube box 125. The second heat exchange tube 126 connects the second tube box 121 and the upper tube box 125.

[0040] The spray system 2 consists of a spray scrubbing tower 201, a nozzle 202, and a spray water pump 203. The spray scrubbing tower 201 has a nozzle 202 at the top and a spray water container at the bottom. The bottom of the spray scrubbing tower 201 has a spray water circulation pipeline, and the spray water circulation pipeline is equipped with a spray water pump 203 and a spray water filter 204 to transport the spray water from the bottom of the tower to the nozzle 202. The lower side wall of the spray scrubbing tower 201 has, from high to low, a spray water replenishment inlet, other exhaust inlets from other areas of the horizontal pulling device, an exhaust inlet of the shaping area connected to the tube side of the heat exchanger 1, and an overflow port for the spray water.

[0041] The cooled hot air exits from the tube side of heat exchanger 1 and enters spray system 2 from the exhaust inlet of the shaping area on the side wall of spray system 2; a discharge outlet and a water cooler are also provided downstream of the spray water filter 204 on the spray water circulation pipeline; the water cooler is equipped with a temperature control valve TV to control the water temperature entering the nozzle 202, and a temperature sensor T1 is installed on the air outlet pipeline at the top of the spray scrubbing tower 201; the temperature control valve TV and the temperature sensor T1 work together to adjust the gas temperature at the air outlet at the top of the spray scrubbing tower 201 by controlling the flow rate of cold water in the water cooler.

[0042] The tube side of heat exchanger 1 functions as follows: The transverse stretching equipment in the transverse stretching workshop typically consists of a preheating zone, a stretching zone, a heat setting zone, a cooling zone, and a buffer zone. Each zone has independent air inlet and outlet. This system is used for exhaust treatment in the transverse stretching workshop. Hot air discharged from the heat setting zone of the transverse stretching device is transported to the system inlet through pipelines. In this application, the tube side inlet of heat exchanger 1 serves as the system inlet. Hot air enters heat exchanger 1 from the inlet and exchanges heat with the cold air in the shell side of heat exchanger 1 through the tube side, thus cooling the hot air. This process effectively recovers the heat from the hot air, preparing it for subsequent processing stages.

[0043] The shell side of heat exchanger 1 has the following function: the cold air input to the shell side of heat exchanger 1 comes from the sizing zone recovery air of the system's suction fan.

[0044] The functions of each unit in the spray system 2 are as follows: the spray water from the nozzles 202 can wash and cool the hot air; the spray water pump 203 is used to transport the spray water from the bottom of the tower to the nozzles 202; a spray water filter 204 is installed on the pipeline where the spray water pump 203 is located to filter impurities in the spray water and ensure the normal operation of the spray system; the overflow port is used to collect the treated wastewater; and the spray water replenishment inlet is used to replenish the spray water volume.

[0045] The function of demister 3 is as follows: After the hot air has been treated by the spray system, the water droplets and impurities it carries are removed, and then it enters demister 3 for further demisting. Demister 3 separates water droplets from the hot air using physical methods, ensuring that the hot air is dry and will not affect subsequent processing steps.

[0046] The function of the electrostatic precipitator 4 is as follows: After being treated by the demister 3, the hot air enters the electrostatic precipitator 4 for oil removal. The electrostatic precipitator 4 uses an electrostatic field to adsorb and collect oil droplets in the hot air, ensuring that the hot air is free of oily impurities.

[0047] The function of the suction fan 5 is as follows: Hot air, after being treated by the electrostatic precipitator 4, enters the suction fan 5 for extraction. The suction fan 5 draws the hot air out of the duct and discharges it into the atmosphere through the exhaust pipe 6. Simultaneously, the suction fan 5 can also adjust the exhaust pressure as needed to meet different production requirements.

[0048] The function of the return air treatment is as follows: after being extracted by the exhaust fan, a portion of the air is returned to other areas of the horizontal support unit through another return air duct. This portion of the return air can be reused, improving energy efficiency.

[0049] Other exhaust ventilation treatment functions are as follows: Exhaust air from other areas of the horizontal ductwork is also collected and transported to the spray system 2 for treatment. After being washed and cooled by the spray system 2, this exhaust air can be reused or discharged through the exhaust stack 6.

[0050] The energy-saving process using the above system can be adjusted according to the requirements of different regions and different product processes. This application lists three operating conditions:

[0051] Normal operating condition: This operating condition is adopted when the average outdoor ambient temperature is ≥20℃; the spray water temperature is adjusted by fully opening valve T1 to control the gas temperature T1 after spraying to drop appropriately, valves V2 and V3 are closed, and valve V1 is opened to allow the purified gas to be discharged to the atmosphere through valve V1 from the exhaust stack; valve V4 is opened to allow the ambient air to enter the heat exchanger 1 through the shell side of the fresh air filter 7 for heat exchange and temperature rise, and then enter the return air duct of the heat setting area. At this time, all return air passes through the fresh air filter, and the return air power comes entirely from the fan in the heat setting area.

[0052] Winter operating condition: This operating condition is adopted when the average outdoor ambient temperature is ≤5℃; the spray water temperature is adjusted by valve T1 to control the gas temperature T1 after spraying to 20℃, valve V1 is closed, valve V4 is slightly opened to stabilize the return air duct pressure, and the opening of valves V2 and V3 is adjusted so that part of the gas enters heat exchanger 1 through valve V2 for heat exchange and temperature rise, and is then sent to the return air duct of the heat setting area. The other part of the gas is sent to the horizontal drawing workshop through valve V3 as a supplement to the fresh air in other areas of the horizontal drawing workshop.

[0053] Intermediate operating condition: This operating condition is adopted when the average outdoor ambient temperature is between 5℃ and 20℃; the spray water temperature is adjusted by valve T1 to control the gas temperature T1 after spraying to 20-25℃, valve V1 is controlled to limit the air volume discharged into the atmosphere, valve V4 is slightly opened to stabilize the pressure of the return air duct, and the opening of valves V2 and V3 is adjusted so that some gas is discharged into the atmosphere through valve V1 from the exhaust stack, some gas enters the heat exchanger through valve V2 for heat exchange and temperature rise, and is sent into the return air duct of the heat setting area, and the other part of the gas is sent into the horizontal drawing workshop through valve V3 as a supplement to the fresh air in other areas of the horizontal drawing workshop.

[0054] In summary, the system of this application can adapt to various operating conditions based on the controllable temperature of the gas after spraying: under normal and winter operating conditions, the system adjusts the operating status of the spray cooling system by controlling the gas temperature T1 after spraying to 20℃ or 20-25℃. By adjusting the temperature of the spray water, the gas temperature can be controlled, thereby affecting the extraction and exhaust of fresh air. In addition, the system regulates gas exhaust and fresh air extraction by opening or closing specific valves.

[0055] This system begins in the heat-setting area of ​​the horizontal stretching unit, where the exhausted hot air is cooled by heat exchanger 1 and then sent to spray system 2 for further cooling. Next, the air passes through a demister, electrostatic precipitator, and exhaust fan. Depending on seasonal energy consumption requirements, a portion can be released into the atmosphere, while the remainder is returned to the horizontal stretching unit for recirculation. The recovered hot air is directly returned to other areas of the horizontal stretching unit via the return air duct, while the remaining portion merges with the air supplied by the fresh air filter 7 and returns to the shell side of heat exchanger 1 for reheating. Finally, it is transported to the heat-setting area of ​​the horizontal stretching unit via the heat-setting hot air return duct. This method not only solves the problems in existing technologies but also reduces energy consumption, improves production efficiency, and minimizes environmental impact.

[0056] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0057] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-energy-saving process for cross-stretching heat exhaust in biaxial film production, characterized in that: The process involves a system including a heat exchanger (1), the tube side outlet of which is connected in sequence to a spray system (2), a demister (3), an electrostatic oil separator (4), a suction fan (5), and an exhaust stack (6); the air drawn out by the suction fan (5) is divided into three pipelines, one of which is discharged into the atmosphere through the exhaust stack (6) and controlled by valve V1; the second of which is connected to the shell side of the heat exchanger (1) through a pipeline and then transported to the heat setting area of ​​the horizontal stretching device, controlled by valve V2; the third of which is transported to other areas of the horizontal stretching device through the horizontal stretching return air pipeline and controlled by valve V3; a fresh air filter (7) is also installed upstream of the shell side of the heat exchanger (1) and controlled by valve V4; the spray system is also equipped with a valve TV that can control the temperature of the gas after spraying; The energy-saving process using the above system includes three operating conditions: When the average outdoor ambient temperature is ≥20℃: valve T1 is fully open, valves V2 and V3 are closed, valve V1 is opened, and gas is discharged to the atmosphere through the exhaust pipe (6) via valve V1; valve V4 is opened, and ambient air is allowed to enter the heat exchanger (1) through the shell side of the fresh air filter (7) for heat exchange and temperature rise. When the average outdoor ambient temperature is ≤5℃: control the gas temperature T1 after spraying to 20℃ through valve T1, close valve V1, slightly open valve V4 to stabilize the pressure of the return air duct, adjust the opening of valves V2 and V3 so that some gas enters heat exchanger 1 through valve V2 for heat exchange and temperature rise, and is then sent to the return air duct of the heat setting area. The other part of the gas is sent to the horizontal drawing workshop through valve V3 as a supplement to the fresh air in other areas of the horizontal drawing workshop. When the average outdoor ambient temperature is between 5℃ and 20℃: control the gas temperature T1 after spraying to 20-25℃ through valve T1, control the V1 valve to limit the air volume discharged into the atmosphere, slightly open the V4 valve to stabilize the pressure of the return air duct, adjust the opening of the V2 and V3 valves so that some gas is discharged into the atmosphere through the V1 valve from the exhaust stack (6), some gas enters the heat exchanger (1) through the V2 valve for heat exchange and temperature rise, and is sent into the return air duct of the heat setting area. The other part of the gas is sent into the horizontal stretching workshop through the V3 valve as a supplement to the fresh air of other areas of the horizontal stretching workshop.

2. The system according to claim 1, characterized in that: The spray system (2) consists of a spray scrubbing tower (201), a nozzle (202) and a spray water pump (203). The spray scrubbing tower (201) has a nozzle (202) at the top and spray water at the bottom. The spray scrubbing tower (201) has a spray water circulation pipeline at the bottom and a spray water pump (203) and a spray water filter (204) on the spray water circulation pipeline to transport the spray water from the bottom of the tower to the nozzle (202). The lower side wall of the spray scrubbing tower (201) is provided with a spray water replenishment inlet, other exhaust inlets from other areas of the horizontal pulling device, a fixed area exhaust inlet connected to the heat exchanger (1) tube side, and an overflow port for the spray water in sequence from high to low.

3. The system according to claim 2, characterized in that: The valve TV is configured as follows: a discharge outlet and a water cooler are provided downstream of the spray water filter (204); the water cooler is equipped with a temperature control valve TV, and a temperature sensor T1 is provided on the air outlet pipe at the top of the spray scrubbing tower (201); the temperature control valve TV is used in conjunction with the temperature sensor T1.

4. The system according to claim 1, characterized in that: The heat exchanger (1) is equipped with a removable filter (13) at the front end of the tube side.

5. The system according to claim 4, characterized in that: The detachable filter (13) is a drawer-type filter with a removable multi-layer stainless steel wire mesh inside. The thickness of the regularized filler of the multi-layer stainless steel wire mesh is 100-200mm.

6. The system according to claim 4, characterized in that: The heat exchanger (1) further includes a fresh air heat exchange chamber (11) for the shaping zone. A hot air heat exchange pipeline structure (12) for the shaping zone is provided on the outside of the fresh air heat exchange chamber (11). The hot air heat exchange pipeline structure (12) for the shaping zone includes a second pipe box (121) and a first pipe box (122) provided at the bottom of the fresh air heat exchange chamber for the shaping zone. A removable filter (13) is provided on the upper part of the first pipe box (122). A removable filter (13) is provided on the outside of the first pipe box (122) and below the removable filter. There is a hot air inlet (123) for the shaping area. The top of the first tube box (122) is provided with a first heat exchange tube (124) that vertically penetrates the fresh air heat exchange chamber (11) of the shaping area. The upper end of the fresh air heat exchange chamber (11) of the shaping area is detachably provided with an upper tube box (125). The top of the second tube box (121) is provided with a second heat exchange tube (126) that vertically penetrates the fresh air heat exchange chamber (11) of the shaping area. The middle of the outer side of the second tube box (121) is provided with a hot air outlet (127) for the shaping area.

7. The system according to claim 6, characterized in that: The fresh air heat exchange chamber (11) of the shaping area includes a heat exchange shell (111), and the two ends of the heat exchange shell (111) in the horizontal direction are respectively provided with a shaping area return air inlet (112) and a shaping area hot air outlet (113).

8. The system according to claim 7, characterized in that: The first heat exchange tube (124) is located on the same side as the hot air outlet (113) of the shaping area; the second heat exchange tube (126) is located on the same side as the return air inlet (cold air) (112) of the shaping area; the first heat exchange tube (124) is connected to the first tube box (122) and the upper tube box (125); the second heat exchange tube (126) is connected to the second tube box (121) and the upper tube box (125).

9. The system according to claim 1, characterized in that: The cooled hot air comes out from the tube side of the heat exchanger (1) and enters the spray system (2) from the exhaust inlet of the shaping area on the side wall of the spray system (2).

10. The system according to claim 1, characterized in that: The air output from other areas of the horizontal pulling device is connected to the side of the spray system (2) through other exhaust pipes.

Images