Waste gas emission control method, device and equipment of drying furnace and storage medium

Abstract

The invention discloses a waste gas emission control method, device and equipment of a drying furnace and a storage medium, and relates to the technical field of industrial waste gas treatment and energy conservation and emission reduction. The waste gas emission control method of the drying furnace comprises the steps that when the drying furnace is in the starting temperature rising stage, a fresh air supplementing fan and a waste gas fan are stopped; when the drying furnace is in the normal production stage, the operation frequency of the fresh air supplementing fan and the operation frequency of the waste gas fan are adjusted according to the number of workpieces; and when the drying furnace is in the production ending stage, the operation frequency is adjusted to be a first preset frequency or the fresh air supplementing fan and the waste gas fan are closed. The energy utilization efficiency is improved, the safety and environmental protection performance of the production process are ensured, energy waste caused by volatilization of volatile organic compounds in the heating process of the drying furnace can be effectively reduced, and the concepts of intelligent manufacturing and green manufacturing are embodied.

Description

Technical Field

[0001] The present application relates to the technical field of industrial waste gas treatment and energy conservation and emission reduction, and in particular to a waste gas emission control method, device, equipment and storage medium of a drying furnace. Background Art

[0002] In the automobile manufacturing process, after the electrophoresis, gluing and painting processes are completed, the coating and glue materials need to be heated and cured in a drying furnace. The solvent components contained in these materials will evaporate into gas when heated and mix with the air in the furnace, resulting in an increase in the content of volatile organic compounds (VOCs). Since VOCs are flammable and explosive, in order to ensure safety, the drying furnace needs to introduce fresh air and exhaust a certain amount of exhaust gas when it is designed to maintain the VOC concentration within a safe range. However, in this process, the exhaust gas takes away a lot of heat, resulting in a waste of energy.

[0003] A common practice is to use a drying furnace exhaust gas comprehensive utilization system, such as the patent CN204286041U, which treats the exhaust gas in the drying chamber through an exhaust gas incinerator to eliminate pollutants and convert the heat in the exhaust gas into effective heat energy. Although this method can meet environmental protection requirements and achieve a certain degree of energy saving, after the equipment is debugged, the fresh air and exhaust gas volume reach a balance state, and the frequency of the fresh air fan and the exhaust fan is fixed, resulting in an equal amount of energetic air being discharged during the operation of the drying furnace, causing heat energy loss.

[0004] The existing practice has the problem of energy waste while maintaining the safe operation of the drying furnace. When the equipment is turned on, since the air volume of fresh air and exhaust gas is a fixed value, energetic air will be continuously discharged, resulting in heat loss. In addition, during periods such as equipment startup and heating, production breaks, meals, and shutdown and cooling, since there are no workpieces or the number of workpieces in the furnace is reduced, the VOC concentration decreases, causing the exhaust gas incinerator to consume more fuel to maintain the purification temperature, further increasing energy consumption. Therefore, how to effectively reduce the energy waste caused by the volatilization of volatile organic compounds during the heating process of the drying furnace has become an urgent problem to be solved.

[0005] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0006] The purpose of this application is to provide a method, device, equipment and storage medium for controlling exhaust gas emissions from a drying furnace, aiming to solve the technical problem of how to effectively reduce the energy waste caused by the volatilization of volatile organic compounds during the heating process of the drying furnace.

[0007] To achieve the above objectives, the present application proposes a method for controlling exhaust gas emissions from a drying furnace, the method comprising:

[0008] When the drying furnace is in the startup and heating stage, stop the fresh air supply fan and the exhaust fan;

[0009] When the drying furnace is in a normal production stage, the operating frequencies of the fresh air supply fan and the exhaust gas fan are adjusted according to the number of workpieces;

[0010] When the drying furnace is in the final stage of production, the operating frequency is adjusted to a first preset frequency or the fresh air supply fan and the exhaust gas fan are turned off.

[0011] In one embodiment, when the drying furnace is in a normal production stage, the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces includes:

[0012] When the drying furnace is in the startup and heating stage and the number of workpieces is within the first preset load range, the operating frequency of the fresh air supply fan and the exhaust gas fan is adjusted to the first preset frequency;

[0013] When the drying furnace is in the startup and heating stage and the number of workpieces is within a second preset load range, the operating frequency is adjusted to a second preset frequency, the lowest value of the second preset load range is greater than or equal to the highest value of the first preset load range, and the second preset frequency is greater than the first preset frequency;

[0014] When the drying furnace is in the startup and heating stage and the number of workpieces is within a third preset load range, the operating frequency is adjusted to a third preset frequency, the lowest value of the third preset load range is greater than or equal to the highest value of the second preset load range, and the third preset frequency is greater than the second preset frequency;

[0015] When the drying furnace is in the startup and heating stage and the number of workpieces is within the fourth preset load range, the operating frequency is adjusted to the fourth preset frequency, the lowest value of the fourth preset load range is greater than or equal to the highest value of the third preset load range, and the fourth preset frequency is greater than the third preset frequency.

[0016] In one embodiment, when the drying furnace is in a normal production stage, after the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, it also includes:

[0017] Obtaining the temperature, humidity and volatile organic compound concentration in the drying oven;

[0018] When at least one of the following conditions is met: the temperature is lower than a preset drying temperature range, the humidity is lower than a preset drying humidity range, and the concentration of volatile organic compounds is lower than a preset concentration, reducing the operating frequency;

[0019] When at least one of the following conditions is met: the temperature is higher than the preset drying temperature range, the humidity is higher than the preset drying humidity range, and the concentration of volatile organic compounds is higher than the preset concentration, the operating frequency is increased.

[0020] In one embodiment, when the drying furnace is in a normal production stage, after the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, it also includes:

[0021] Get the type and volume of the workpiece;

[0022] When the type belongs to the first preset type or the volume is smaller than the first preset volume, adjusting the operating frequency to a first preset frequency range;

[0023] When the type belongs to the second preset type, the operating frequency is adjusted to a second preset frequency range, the thermal conductivity of the second preset type is weaker than the thermal conductivity of the first preset type, and the lowest value of the second preset frequency range is greater than the highest value of the first preset frequency range;

[0024] When the type belongs to the third preset type or the volume is greater than the second preset volume, the operating frequency is adjusted to the third preset frequency range, the thermal conductivity of the third preset type is weaker than the thermal conductivity of the second preset type, the lowest value of the third preset frequency range is greater than the highest value of the second preset frequency range, and the second preset volume is greater than the first preset volume.

[0025] In one embodiment, the method further comprises:

[0026] The waste gas is discharged into the waste gas incineration device through the waste gas fan;

[0027] Obtaining the concentration of volatile organic compounds in the waste gas incineration device;

[0028] When the concentration of the volatile organic compounds is lower than a preset emission concentration threshold, the waste gas after incineration is discharged into a waste gas waste heat recovery device or into the atmosphere through the waste gas fan.

[0029] In one embodiment, when the drying furnace is in a normal production stage, after the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, it also includes:

[0030] Obtaining actual rotation speeds of the fresh air supply fan and the exhaust gas fan;

[0031] Calculate the speed difference according to the operating frequency and the actual speed;

[0032] The basic information of the fan whose speed difference is greater than a preset speed difference threshold and the speed difference are sent to a preset device as fault information.

[0033] In one embodiment, the step of calculating the speed difference according to the operating frequency and the actual speed comprises:

[0034] Obtaining the pole pairs of the fresh air supply fan and the exhaust gas fan;

[0035] Calculate the theoretical speed according to the operating frequency and the number of pole pairs;

[0036] A speed difference is calculated according to the actual speed and the theoretical speed.

[0037] In addition, to achieve the above purpose, the present application also proposes a waste gas emission control device for a drying furnace, the device comprising:

[0038] The heating module is used to stop the fresh air supply fan and the exhaust gas fan when the drying furnace is in the startup and heating stage;

[0039] A production module, used for adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces when the drying furnace is in a normal production stage;

[0040] The end module is used to adjust the operating frequency to a first preset frequency or turn off the fresh air supply fan and the exhaust gas fan when the drying furnace is in the end stage of production.

[0041] In addition, to achieve the above-mentioned objectives, the present application also proposes a waste gas emission control device for a drying furnace, the device comprising: a memory, a processor, and a computer program stored on the memory and executable on the processor, the computer program being configured to implement the steps of the waste gas emission control method for a drying furnace as described above.

[0042] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by the processor, the steps of the exhaust gas emission control method of the drying furnace as described above are implemented.

[0043] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the exhaust gas emission control method of the drying furnace as described above are implemented.

[0044] One or more technical solutions proposed in this application have at least the following technical effects:

[0045] When the drying furnace is in the startup and heating stage, the fresh air supply fan and the exhaust gas fan are stopped; when the drying furnace is in the normal production stage, the operating frequency of the fresh air supply fan and the exhaust gas fan is adjusted according to the number of workpieces; when the drying furnace is in the end of production, the operating frequency is adjusted to the first preset frequency or the fresh air supply fan and the exhaust gas fan are turned off. First, in the startup and heating stage, the system will stop the operation of the fresh air supply fan and the exhaust gas fan, because there are no workpieces in the furnace at this time, and there is no need to introduce fresh air or exhaust gas. This can reduce energy consumption, speed up the heating speed, improve energy efficiency, and reduce heat loss. Subsequently, in the normal production stage, the system will dynamically adjust the fan operating frequency according to the number of workpieces in the furnace to ensure that the VOC concentration is maintained within a safe range, while optimizing energy use, reducing unnecessary energy waste, and maintaining production efficiency. Finally, at the end of production, the system will adjust the fan's operating frequency to a very low first preset frequency or shut it down completely to reduce energy consumption when there is no production activity, significantly reduce energy consumption, reduce mechanical wear, extend equipment life, and provide a safe environment for equipment shutdown and maintenance. This series of control steps not only improves energy utilization efficiency and ensures the safety and environmental protection of the production process, but also effectively reduces the energy waste caused by the volatilization of volatile organic compounds during the heating process of the drying furnace, reflecting the concept of intelligent manufacturing and green manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0048] Figure 1 A schematic diagram of a process flow provided in Example 1 of the method for controlling exhaust gas emission of a drying furnace of the present application;

[0049] Figure 2A schematic diagram of a drying furnace waste gas treatment and emission system provided in Example 1 of the waste gas emission control method for a drying furnace of the present application;

[0050] Figure 3 A schematic flow chart of the second embodiment of the waste gas emission control method for the drying furnace of the present application;

[0051] Figure 4 This is a schematic diagram of the module structure of the exhaust gas emission control device of the drying furnace in the embodiment of the present application;

[0052] Figure 5 This is a schematic diagram of the equipment structure of the hardware operating environment involved in the exhaust gas emission control method of the drying furnace in the embodiment of the present application.

[0053] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0054] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0055] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0056] After the electrophoresis, gluing and painting processes in automobile manufacturing, the drying furnace is used to heat and cure the coating and glue materials. During the process, the solvent evaporates to form VOC, which increases the risk of flammability and explosion of the air in the furnace. To ensure safety, fresh air needs to be introduced and exhaust gas needs to be discharged to control the VOC concentration, but this also causes a large amount of heat to be lost with the exhaust gas, resulting in energy waste. Although the use of an exhaust gas incinerator system can treat pollution and recover some heat energy, due to the fixed frequency of the fresh air and exhaust fans, the energetic air is continuously discharged during the operation of the drying furnace, and there is still a significant heat energy loss. Especially when the equipment is turned on and heated up, during rest periods, and when it is turned off and cooled, due to the reduction in VOC concentration, the exhaust gas incineration requires additional fuel to maintain the temperature, further exacerbating the energy consumption problem.

[0057] The main solution of the embodiment of the present application is: during the startup and heating stage of the drying furnace, the system suspends the fan to reduce energy consumption and accelerate the heating; during normal production, the fan frequency is adjusted according to the number of workpieces to control VOC concentration and save energy; after production, the fan frequency is reduced or turned off to reduce energy consumption and extend equipment life.

[0058] It should be noted that the execution subject of the embodiment of the present application can be a computing service device with data processing, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or an electronic device capable of realizing the above functions, a fan control system, etc. The fan control system is taken as an example to illustrate this embodiment and the following embodiments.

[0059] The present application installs contact switches or counting sensors at the inlet and outlet of the drying furnace. When the workpiece enters the drying furnace, the contact switch is triggered and the workpiece count is increased; when the workpiece leaves the drying furnace, the contact switch is triggered and the workpiece count is decreased. The counting data is counted by the calculation module in the PLC control system to monitor the number of workpieces in the furnace in real time and adjust the fan frequency according to the change in the number.

[0060] Based on this, the embodiment of the present application provides a method for controlling exhaust gas emissions from a drying furnace, referring to Figure 1 , Figure 1 This is a flow chart of the first embodiment of the waste gas emission control method of the drying furnace of the present application.

[0061] Please refer to Figure 2 , Figure 2 A schematic diagram of a drying furnace waste gas treatment and emission system provided in Example 1 of the waste gas emission control method of the drying furnace of the present application shows the layout of the drying furnace waste gas treatment and emission system, which includes multiple ternaries (which may refer to the various working units or processing stages of the drying furnace), which are connected by pipes to form a network for waste gas collection and treatment. The waste gas is first extracted through the waste gas fan and then sent to the waste gas incineration equipment, where the volatile organic compounds in the waste gas are incinerated at high temperature and converted into harmless substances. The incinerated waste gas may be sent to the waste gas waste heat recovery device to recover heat for other production processes or to heat fresh air, thereby improving energy efficiency. Finally, the treated waste gas is discharged into the atmosphere through the chimney. The furnace discharge counter in the figure is used to monitor and control the flow of workpieces, record the number of workpieces, and ensure that the system dynamically adjusts the operating frequency of the fan according to the actual production load to achieve the goals of energy saving and environmental protection. The design of the entire system is to optimize the energy use of the drying furnace while ensuring safety and environmental protection during the production process.

[0062] In this embodiment, the exhaust gas emission control method of the drying furnace includes steps S10 to S30:

[0063] Step S10, when the drying furnace is in the startup and heating stage, the fresh air supply fan and the exhaust gas fan are stopped;

[0064] It should be noted that the drying furnace refers to the equipment used to heat and cure the coating and glue materials after the electrophoresis, gluing and painting operations on the car. It cures the coating and glue materials through the heating process. Usually, these materials contain solvent components in different proportions. During the heating process, these solvents will evaporate to form gaseous state and mix with the air in the furnace, resulting in an increase in the VOC (volatile organic compound) content. The startup and heating stage refers to the process from the start of the drying furnace to reaching the set working temperature (for example, 180-200℃ for electrophoresis drying, 150-160℃ for glue and topcoat furnaces). At this stage, there are no workpieces inside the drying furnace, or the number of workpieces is not enough to affect the VOC concentration in the furnace, so there is no need to supplement fresh air and discharge exhaust gas. The fresh air supply fan refers to a device used to introduce fresh air into the drying furnace. Its main function is to reduce the VOC concentration in the furnace by supplying fresh air during the drying process to keep the VOC concentration within a safe range and take away some heat to prevent the temperature from being too high. In this embodiment, the fresh air supply fan needs to have a frequency conversion function so that the air volume can be automatically adjusted according to different working conditions. The exhaust gas fan refers to a device used to exhaust exhaust gas from the drying furnace. These exhaust gases contain a high concentration of VOCs and need to be discharged and treated to ensure safety and environmental protection. The exhaust gas fan also needs to have a frequency conversion function so that the exhaust volume can be automatically adjusted according to the changes in the VOC concentration and the number of workpieces in the furnace.

[0065] The fan control system uses contact switches or counting sensors or temperature sensors installed at the inlet and outlet of the drying furnace to monitor the flow of workpieces. When the workpiece enters the drying furnace, the inlet sensor triggers a signal, and the system records the increase in the number of workpieces; when the workpiece leaves the drying furnace, the outlet sensor triggers a signal, and the system records the decrease in the number of workpieces. The programmable logic controller (PLC) inside the system calculates the total number of workpieces in the furnace in real time based on the input signal of the sensor. Different logic control programs are preset inside the PLC to identify the different working stages of the drying furnace. The PLC determines the stage of the drying furnace based on the changes in the number of workpieces in the furnace and the changes in the temperature. For example, if the number of workpieces in the furnace is zero or close to zero and the temperature of the drying furnace is low, the system identifies that the drying furnace is in the start-up and heating stage; if the number of workpieces is greater than a preset value, the system determines that the drying furnace has entered the formal production stage.

[0066] It is understandable that, firstly, the fan control system will detect that the drying furnace is in the startup and heating stage. At this time, there are no workpieces or very few workpieces in the furnace, so there is no need to supplement fresh air and discharge exhaust gas. The control system then sends a stop command to the fresh air supply fan and the exhaust gas fan; secondly, since the fresh air supply fan stops working, no fresh air will be introduced into the furnace, so no extra energy will be consumed to heat the fresh air. At the same time, the stopping of the exhaust gas fan means that no high-temperature exhaust gas will be discharged, thereby reducing heat loss; finally, the stopping of these two fans enables the drying furnace to reach the required operating temperature faster and saves a lot of energy in the entire heating process, because no extra energy is required to heat the fresh air and treat the exhaust gas. This not only improves energy efficiency, but also reduces the impact on the environment, laying the foundation for efficient operation in the formal production stage.

[0067] Step S20, when the drying furnace is in a normal production stage, adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces;

[0068] It should be noted that the normal production stage refers to the continuous production process in which the drying furnace starts to process workpieces after it has started up and reached the set working temperature. During this stage, workpieces will continue to flow in and out of the drying furnace, and the VOC concentration will increase due to the volatilization of the solvent. Therefore, it is necessary to introduce fresh air and discharge exhaust gas to maintain the VOC concentration within a safe range. The number of workpieces refers to the total number of workpieces being processed in the drying furnace at a specific moment. This number is obtained through the contact switch or counting sensor installed at the inlet and outlet of the drying furnace. Changes in the number of workpieces directly affect the amount of VOC volatilization in the furnace, because each workpiece will release a certain amount of solvent during the drying process, thereby affecting the VOC concentration. The operating frequency refers to the working frequency set by the variable frequency drive of the fresh air supply fan and the exhaust gas fan. This frequency determines the fan speed, which in turn affects the air volume. In the variable frequency fan system, the air volume can be accurately controlled by adjusting the operating frequency to adapt to different production needs and VOC control requirements. In the normal production stage, according to the changes in the number of workpieces, the fan control system will automatically adjust the fan's operating frequency to ensure that the fresh air supply and exhaust gas emissions match the VOC volatilization in the furnace, while maintaining a balanced state of slight negative pressure in the drying furnace.

[0069] It can be understood that, firstly, the fan control system will monitor and record the inflow and outflow of workpieces in real time through sensors installed at the inlet and outlet of the drying furnace, so that the total number of workpieces in the furnace at any time can be accurately calculated; secondly, the control system will automatically adjust the operating frequency of the variable frequency drives of the fresh air supply fan and the exhaust gas fan according to the preset logic based on the number of workpieces. For example, when the number of workpieces is small, the fan frequency is reduced to reduce energy consumption, and when the number of workpieces is large, the fan frequency is increased to ensure that the VOC concentration is controlled within a safe range; finally, this automatic adjustment of the fan frequency can ensure that the drying furnace can operate efficiently under different production loads, reduce energy waste caused by excessive ventilation, and keep the VOC concentration at a safe level, avoid environmental pollution and safety risks, and achieve the dual goals of energy saving and environmental protection.

[0070] As an example, when the drying furnace is in the normal production stage, after the step of adjusting the operating frequencies of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, it also includes: obtaining the temperature, humidity and volatile organic compound concentration in the drying furnace; when at least one of the temperature is lower than the preset drying temperature range, the humidity is lower than the preset drying humidity range, and the volatile organic compound concentration is lower than the preset concentration, reducing the operating frequency; when at least one of the temperature is higher than the preset drying temperature range, the humidity is greater than the preset drying humidity range, and the volatile organic compound concentration is greater than the preset concentration, increasing the operating frequency.

[0071] Temperature refers to the actual temperature inside the drying oven during the drying process. This temperature needs to be maintained within a certain range to ensure that the coating on the workpiece can be uniformly and fully cured. Humidity refers to the air humidity inside the drying oven. Humidity control is also important for the curing process of the coating. Excessive humidity may affect the quality and drying speed of the coating. Volatile organic compound concentration refers to the concentration of VOC in the air inside the drying oven. The control of VOC concentration is to ensure the health of workers and production safety, because high concentrations of VOC are harmful and may cause explosions. The preset drying temperature range refers to the ideal temperature range set to ensure coating quality and drying efficiency. For example, the preset drying temperature range for electrophoresis drying may be 180-200℃, while the preset drying temperature range for glue and topcoat ovens may be 150-160℃. The preset drying humidity range refers to the ideal humidity range set to ensure that the coating curing process is not affected by excessive humidity. For example, the preset drying humidity range may be 30%-50% RH (relative humidity). The preset concentration refers to the upper limit of VOC concentration set to ensure safety and environmental protection. For example, the preset VOC concentration may be 100 ppm (parts per million). If it exceeds this value, measures must be taken to reduce the concentration, such as increasing exhaust emissions.

[0072] First, the fan control system obtains the temperature, humidity and VOC concentration data in the drying furnace in real time through the built-in sensor, and compares these real-time data with the preset optimal drying conditions to determine whether the current environment meets the production requirements; secondly, when the system detects that the temperature is lower than the preset drying temperature range, the humidity is lower than the preset drying humidity range, or the VOC concentration is lower than the preset concentration, the control system will automatically reduce the operating frequency of the fresh air supply fan and the exhaust fan to reduce air flow, reduce energy consumption, and prevent heat loss and low humidity caused by excessive ventilation; then, on the contrary, when the system finds that the temperature is higher than the preset drying temperature range, the humidity is higher than the preset drying humidity range, or the VOC concentration is higher than the preset concentration, the control system will automatically increase the operating frequency of the fan to increase the air flow, enhance the heat exchange and exhaust gas emission efficiency, so as to ensure that the environmental conditions in the drying furnace remain within the optimal range. Finally, this dynamic adjustment mechanism can effectively optimize the drying process, improve production efficiency, reduce energy consumption, and ensure safety and environmental protection at the same time, and avoid excessive VOC concentration.

[0073] As an example, when the drying furnace is in the normal production stage, after the step of adjusting the operating frequencies of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, it also includes: obtaining the type and volume of the workpiece; when the type belongs to the first preset type or the volume is less than the first preset volume, adjusting the operating frequency to the first preset frequency range; when the type belongs to the second preset type, adjusting the operating frequency to the second preset frequency range, the thermal conductivity of the second preset type is weaker than the thermal conductivity of the first preset type, and the lowest value of the second preset frequency range is greater than the highest value of the first preset frequency range; when the type belongs to the third preset type or the volume is greater than the second preset volume, adjusting the operating frequency to the third preset frequency range, the thermal conductivity of the third preset type is weaker than the thermal conductivity of the second preset type, the lowest value of the third preset frequency range is greater than the highest value of the second preset frequency range, and the second preset volume is greater than the first preset volume.

[0074] Type refers to the material type of the workpiece being processed in the drying oven. Different types of materials require different drying conditions due to their different physical properties. Volume refers to the size of a single workpiece in the drying oven. The size of the volume affects the efficiency of heat transfer and the time required during the drying process. The first preset type refers to the preset first type of workpiece material, such as metal. Metals usually have good thermal conductivity, so the required drying conditions may be different from those of materials with poor thermal conductivity. The first preset volume refers to a preset volume threshold. Workpieces below this volume will be classified as smaller workpieces. For example, the first preset volume may be 0.5 cubic meters. The first preset frequency range refers to the fan operating frequency range set for the first preset type or workpieces with a volume less than the first preset volume. For example, metal workpieces or workpieces with a smaller volume may require the fan to run in the frequency range of 30-40Hz. The second preset type refers to the preset second type of workpiece material, such as paper products. Paper products usually have poorer thermal conductivity than metals. The second preset frequency range refers to the fan operating frequency range set for the second preset type. Due to the weaker thermal conductivity of paper products, a higher frequency range may be required to ensure the drying effect, such as 40-50Hz. Thermal conductivity refers to the ability of a material to conduct heat. Materials with good thermal conductivity can transfer heat faster, while materials with poor thermal conductivity transfer heat slower. The third preset type refers to the preset third type of workpiece material, such as plastic. The thermal conductivity of plastic is generally worse than that of paper products. The second preset volume refers to another preset volume threshold. Workpieces greater than the first preset volume but less than or equal to the second preset volume will be classified as medium-volume workpieces. For example, the second preset volume may be 1 cubic meter. The third preset frequency range refers to the fan operating frequency range set for the third preset type or workpieces with a volume greater than the second preset volume, such as 50-60Hz. Since plastics have weaker thermal conductivity, a higher frequency range is required to ensure the drying effect.

[0075] First, the control system obtains the type and volume information of each workpiece through sensors or input data; then, based on this information, if the workpiece is metal or the volume is less than the preset small volume threshold, the control system will automatically adjust the operating frequency of the fresh air supply fan and the exhaust fan to a lower range, such as 30-40Hz, because metal workpieces have good thermal conductivity and require a lower heat exchange frequency; then, if the workpiece is paper products, the control system will increase the fan operating frequency to a medium range, such as 40-50Hz, because the thermal conductivity of paper products is worse than that of metal, so a higher frequency is required to ensure heat transfer; finally, if the workpiece is plastic or the volume is greater than the preset large volume threshold, the control system will adjust the fan operating frequency to a higher range, such as 50-60Hz, because the thermal conductivity of plastics is worse than that of paper products, and more heat exchange is required to ensure the drying effect. Through such adjustments, the control system can accurately control the drying process according to the characteristics and volume of different workpieces to achieve the best drying effect and energy efficiency.

[0076] As an example, the method also includes: discharging the exhaust gas into a waste gas incineration device through an exhaust gas fan; obtaining the concentration of volatile organic compounds in the waste gas incineration device; when the concentration of volatile organic compounds is lower than a preset emission concentration threshold, discharging the incinerated exhaust gas into a waste gas waste heat recovery device or into the atmosphere through the exhaust gas fan.

[0077] Waste gas refers to the gas containing volatile organic compounds generated by the drying furnace during the drying process. These gases are volatilized by the coating material at high temperature and usually need to be collected and treated to avoid harm to the environment and human health. Waste gas incineration device is a device used to treat waste gas containing VOC. It converts VOC into harmless substances such as carbon dioxide and water vapor through high-temperature combustion. This device usually includes a combustion chamber, a burner and a control system to ensure that the waste gas is discharged after meeting environmental protection standards. The preset emission concentration threshold refers to the maximum allowable concentration of VOC set to ensure that waste gas emissions comply with environmental regulations and safety standards. For example, environmental regulations in a certain area may stipulate that the emission concentration of VOC shall not exceed 50ppm (parts per million), which is a legal or standard limit to ensure that the impact of exhaust gas on the environment is minimized. Waste gas waste heat recovery device is a system that can recover and reuse heat from waste gas. This device usually includes a heat exchanger that can capture the heat in the waste gas and transfer it to other media, such as air or water, for heating or other industrial processes, which not only reduces energy waste but also improves overall energy efficiency.

[0078] First, the control system will instruct the exhaust gas fan to extract the exhaust gas containing volatile organic compounds in the drying furnace and transport it to the exhaust gas incineration device for high-temperature combustion treatment; then, the system will monitor and obtain the VOC concentration data in the exhaust gas after combustion in real time through the sensor installed in the incineration device to ensure that it complies with environmental regulations and safety standards; finally, when the VOC concentration is detected to be lower than the preset emission concentration threshold, such as 50ppm, the control system may transport the treated exhaust gas through the exhaust gas fan to the exhaust gas waste heat recovery device to recycle the heat therein, or directly discharge the exhaust gas into the atmosphere while ensuring environmental safety. This treatment process not only ensures the environmentally friendly treatment of exhaust gas, but also realizes the efficient use of energy.

[0079] As an example, when the drying furnace is in the normal production stage, after the step of adjusting the operating frequencies of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, it also includes: obtaining the actual rotational speeds of the fresh air supply fan and the exhaust gas fan; calculating the rotational speed difference according to the operating frequency and the actual rotational speed; and sending the basic information of the fan whose rotational speed difference is greater than a preset rotational speed difference threshold and the rotational speed difference as fault information to a preset device.

[0080] The actual speed refers to the actual operating speed of the fresh air supply fan and the exhaust fan at a specific moment, usually measured in revolutions per minute (RPM). This speed can be monitored in real time by the speed sensor installed on the fan. The speed difference refers to the difference between the actual speed of the fan and its theoretical speed set according to the operating frequency. This difference is obtained by calculating the difference between the actual speed and the set speed, and is used to evaluate whether the fan is operating normally according to the requirements of the control system. The preset speed difference threshold is a pre-set value used to determine whether the fan speed is within an acceptable error range. For example, if the preset speed difference threshold is set to 5RPM, any speed difference exceeding this difference is considered abnormal. The setting of this threshold depends on the model and performance requirements of the fan. Basic information refers to the identification information of the fan, such as model, serial number, installation location, etc., as well as the current operating status, such as operating frequency, current, voltage, etc. This information helps to quickly identify the problem fan and perform fault diagnosis. Fault information refers to the data generated by the system containing the basic information and speed difference of the faulty fan when the speed difference of the fan exceeds the preset speed difference threshold. This information is used to notify maintenance personnel or the automatic control system to handle the fault. The preset device refers to the target device or system that receives fault information, such as the monitoring system in the central control room, the handheld terminal of the maintenance personnel, or the cloud service platform. For example, a factory may have a central monitoring system, and all equipment fault information will be sent here for centralized management and response.

[0081] First, the control system obtains the actual speed data of the fresh air supply fan and the exhaust gas fan in real time through the speed sensors connected to them. These data reflect the current operating speed of the fan. Then, the system compares these actual speeds with the theoretical speeds set according to the operating frequency, and calculates the speed difference, that is, the deviation between the actual speed and the set speed. Finally, if this speed difference exceeds the pre-set threshold, such as 5RPM, the control system will consider that the fan may be abnormal, and then package the basic information of the fan, such as model, location and current speed difference, into fault information, and send it to the central monitoring system or the maintenance personnel's handheld terminal and other preset devices through the preset communication path, so that the maintenance team can quickly identify the problem and take corresponding maintenance measures. This process ensures the reliability of the fan operation and the safety of the drying furnace operation.

[0082] As an example, the step of calculating the speed difference based on the operating frequency and the actual speed includes: obtaining the pole pairs of the fresh air supply fan and the exhaust gas fan; calculating the theoretical speed based on the operating frequency and the pole pairs; and calculating the speed difference based on the actual speed and the theoretical speed.

[0083] The number of pole pairs refers to the number of magnetic field poles inside the motor. In a motor (especially a DC motor or a synchronous motor), the number of pole pairs determines the synchronous speed of the motor, that is, the speed that the motor rotor should reach without considering slip. The number of pole pairs is directly related to the motor speed. The more pole pairs, the lower the motor speed, and vice versa. The number of pole pairs is a basic parameter for motor design and can usually be found in the motor specification manual. The theoretical speed refers to the motor speed calculated based on the motor's power supply frequency and the number of pole pairs. For AC motors, the theoretical speed can be calculated using the following formula:

[0084]

[0085] Where n is the theoretical speed (in RPM), f is the operating frequency (Hz), p is the number of pole pairs, and 60 is a constant that converts seconds to minutes. This calculation gives the speed that the motor should run at in ideal conditions, without taking into account any losses or differences in actual operation.

[0086] First, the control system obtains the number of pole pairs of the fresh air supply fan and the exhaust fan from their motor specifications. This is a fixed parameter that determines the maximum speed that the motor can reach. Then, the system uses this pole pair number and the set operating frequency to calculate the speed that the motor should theoretically reach, i.e., the theoretical speed, based on the calculation formula for the motor speed. Finally, the system compares the speed actually measured by the sensor (actual speed) with the theoretical speed calculated previously to obtain the difference between the two, i.e., the speed difference. This difference reflects the deviation between the actual operating state of the motor and the expected state, and is an important parameter for evaluating motor performance and diagnosing potential problems.

[0087] Step S30, when the drying furnace is in the end of production, the operating frequency is adjusted to a first preset frequency or the fresh air supply fan and the exhaust gas fan are turned off.

[0088] It should be noted that the end of production stage refers to the stage when the drying furnace has completed all scheduled production tasks within a day or a production cycle, and no new workpieces enter the drying furnace for drying. At this time, there are no or only a few workpieces left inside the drying furnace, so there is no need for fresh air replenishment and exhaust gas emissions as in the regular production stage. The first preset frequency refers to a specific, lower frequency value, which is used to adjust the operating speed of the fresh air replenishment fan and the exhaust gas fan in a specific operation stage (the end of production stage), which is 20Hz in this embodiment.

[0089] It is understandable that when the drying furnace completes a day's production task and enters the end of production, the control system will automatically reduce the operating frequency of the fresh air supply fan and the exhaust fan to a relatively low first preset frequency, or directly shut down these fans. This is done because at the end of production, no new workpieces enter the furnace, the generation of VOCs and the heat demand are greatly reduced, so a large amount of fresh air supply and exhaust gas emissions are not required. By reducing the operating frequency of the fan or shutting down the fan, energy consumption can be significantly reduced, energy costs can be saved, and mechanical wear can be reduced, and the service life of the fan can be extended. In addition, this also helps to slowly reduce the temperature in the furnace, providing safety for equipment shutdown and subsequent maintenance work.

[0090] This embodiment provides a method for controlling exhaust gas emissions from a drying furnace. When the drying furnace is in the startup and heating stage, the fresh air supply fan and the exhaust gas fan are stopped; when the drying furnace is in the normal production stage, the operating frequency of the fresh air supply fan and the exhaust gas fan is adjusted according to the number of workpieces; when the drying furnace is in the end of production, the operating frequency is adjusted to a first preset frequency or the fresh air supply fan and the exhaust gas fan are turned off. First, in the startup and heating stage, the system will stop the operation of the fresh air supply fan and the exhaust gas fan, because there are no workpieces in the furnace at this time, and there is no need to introduce fresh air or exhaust gas. This can reduce energy consumption, speed up the heating speed, improve energy efficiency, and reduce heat energy loss. Subsequently, in the normal production stage, the system will dynamically adjust the operating frequency of the fan according to the number of workpieces in the furnace to ensure that the VOC concentration is maintained within a safe range, while optimizing energy use, reducing unnecessary energy waste, and maintaining production efficiency. Finally, at the end of production, the system will adjust the fan's operating frequency to a very low first preset frequency or shut it down completely to reduce energy consumption when there is no production activity, significantly reduce energy consumption, reduce mechanical wear, extend equipment life, and provide a safe environment for equipment shutdown and maintenance. This series of control steps not only improves energy utilization efficiency and ensures the safety and environmental protection of the production process, but also effectively reduces the energy waste caused by the volatilization of volatile organic compounds during the heating process of the drying furnace, reflecting the concept of intelligent manufacturing and green manufacturing.

[0091] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the above-mentioned embodiment 1 can refer to the above introduction, and will not be repeated later. Figure 3 , Figure 3 This is a flow chart of the second embodiment of the waste gas emission control method of the drying furnace of the present application. Step S20 of the waste gas emission control method of the drying furnace includes steps S21 to S24:

[0092] Step S21, when the drying furnace is in the startup and heating stage and the number of workpieces is within the first preset load range, adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan to the first preset frequency;

[0093] It should be noted that the first preset load range refers to a specific range of the number of workpieces in the drying furnace during the startup and heating stage, which is used to determine the frequency of the fan operation. Specifically, the first preset load range refers to a load that is 30% lower than the full load state. For example, if the drying furnace can process 100 workpieces at the same time under full load, then the first preset load range is the situation where the number of workpieces processed simultaneously in the furnace is less than 30. The first preset frequency refers to the specific operating frequency set for the fresh air supply fan and the exhaust gas fan. In this embodiment, the first preset frequency is 20Hz, which means that during the startup and heating stage and when the number of workpieces is less than 30% of the full load, the fan will be set to operate at a frequency of 20 revolutions per minute.

[0094] It can be understood that, firstly, the control system will monitor the number of workpieces in the furnace through sensors installed at the inlet and outlet of the drying furnace to determine whether the current load is lower than 30% of the full load state, that is, whether it is within the first preset load range; secondly, once it is confirmed that the number of workpieces meets the conditions, the system will automatically issue a command to adjust the operating frequency of the fresh air supply fan and the exhaust gas fan to the preset low-frequency state, such as setting it to 20Hz. This is done to reduce unnecessary air exchange when the VOC concentration in the furnace is low, thereby reducing energy consumption, because under this load, not too much fresh air is needed to reduce the VOC concentration, nor is it necessary to emit too much hot exhaust gas; finally, this adjustment can effectively save energy, reduce heat loss, speed up the heating rate, prepare for formal production, while reducing mechanical wear, extending the service life of the fan, and ensuring the economy and environmental friendliness of the drying furnace operation.

[0095] Step S22, when the drying furnace is in the startup and heating stage and the number of workpieces is within a second preset load range, adjusting the operating frequency to a second preset frequency, wherein the lowest value of the second preset load range is greater than or equal to the highest value of the first preset load range, and the second preset frequency is greater than the first preset frequency;

[0096] It should be noted that the second preset load range refers to a specific range of the number of workpieces in the drying furnace when it is in the startup and heating stage, which is used to determine the frequency of the fan operation. The lowest value of this range is greater than or equal to the highest value of the first preset load range. For example, the second preset load range may be 30% to 50% of the number of workpieces. Assuming that the drying furnace can process 100 workpieces at full load, then the second preset load range is that the number of workpieces processed simultaneously in the furnace is between 30 and 50. The second preset frequency refers to the specific operating frequency set for the fresh air supply fan and the exhaust gas fan, which is used to operate the fan within a specific load range (such as the second preset load range). For example, the second preset frequency may be 30Hz, which means that during the startup and heating stage and when the number of workpieces is between 30% and 50%, the fan will be set to run at a frequency of 30 revolutions per minute.

[0097] It can be understood that, first, the control system will monitor the number of workpieces inside the drying furnace through sensors to determine whether they are within the second preset load range, that is, the number of workpieces has reached between 30% and 50% of the full load; secondly, when the sensor data shows that the number of workpieces falls within this range, the control system will automatically issue a command to increase the operating frequency of the fresh air supply fan and the exhaust gas fan from a lower first preset frequency, such as 20Hz, to a higher second preset frequency, such as 30Hz. This is because with more workpieces, more fresh air is needed to reduce the VOC concentration and maintain the temperature in the furnace, while more exhaust gas is discharged to keep the furnace environment safe and stable; finally, this method of automatically adjusting the fan frequency according to the actual load can ensure that the drying furnace can operate efficiently under different production loads, which not only ensures production safety, but also optimizes energy use, avoids energy waste, and improves overall energy efficiency and production efficiency.

[0098] Step S23, when the drying furnace is in the startup and heating stage and the number of workpieces is within a third preset load range, adjusting the operating frequency to a third preset frequency, the lowest value of the third preset load range is greater than or equal to the highest value of the second preset load range, and the third preset frequency is greater than the second preset frequency;

[0099] It should be noted that the third preset load range refers to a specific range of the number of workpieces in the drying furnace during the startup and heating stage, which is used to determine the frequency of the fan operation. The lowest value of this range is greater than or equal to the highest value of the second preset load range. For example, the third preset load range may be 50% to 80% of full load. Assuming that the drying furnace can process 100 workpieces at full load, the third preset load range is that the number of workpieces processed simultaneously in the furnace is between 50 and 80. The third preset frequency refers to the specific operating frequency set for the fresh air supply fan and the exhaust gas fan, which is used to operate the fan within a specific load range (such as the third preset load range). For example, the third preset frequency may be 40Hz, which means that during the startup and heating stage and when the number of workpieces is between 50% and 80% of the full load, the fan will be set to operate at a frequency of 40 revolutions per minute.

[0100] It can be understood that, firstly, the control system monitors the number of workpieces in the furnace in real time through sensors connected to the drying furnace to determine whether they are in the third preset load range, that is, the number of workpieces is between 50% and 80% of the full load; secondly, when the sensor shows that the number of workpieces reaches this range, the control system will automatically adjust the inverters of the fresh air supply fan and the exhaust gas fan to increase the operating frequency of the fan from the previous 30Hz to 40Hz. This is because under this load, more workpieces mean more VOC generation and heat demand, and more fresh air is needed to reduce the VOC concentration and maintain the temperature in the furnace, while more exhaust gas is discharged to keep the furnace environment safe and stable; finally, this precise adjustment ensures that the drying furnace can operate efficiently under different load conditions, which not only ensures production safety, but also optimizes energy use, avoids energy waste, improves overall energy efficiency and production efficiency, and ensures the economy and environmental friendliness of the drying furnace operation.

[0101] Step S24, when the drying furnace is in the startup and heating stage and the number of workpieces is within the fourth preset load range, the operating frequency is adjusted to the fourth preset frequency, the lowest value of the fourth preset load range is greater than or equal to the highest value of the third preset load range, and the fourth preset frequency is greater than the third preset frequency.

[0102] It should be noted that the fourth preset load range refers to a specific range of the number of workpieces in the drying furnace during the startup and heating stage, which is used to determine the frequency of the fan operation. The lowest value of this range is greater than or equal to the highest value of the third preset load range. For example, the fourth preset load range may be 80% to 100% of the full load. Assuming that the drying furnace can process 100 workpieces at full load, the fourth preset load range is the number of workpieces processed simultaneously in the furnace between 80 and 100. The fourth preset frequency refers to the specific operating frequency set for the fresh air supply fan and the exhaust gas fan, which is used to operate the fan within a specific load range (such as the fourth preset load range). For example, the fourth preset frequency may be 50Hz, which means that during the startup and heating stage and when the number of workpieces is between 80% and 100% of the full load, the fan will be set to run at a frequency of 50 revolutions per minute.

[0103] It is understandable that, first, the control system will monitor the number of workpieces inside the drying furnace in real time through sensors to determine whether they are in the fourth preset load range, that is, the number of workpieces reaches between 80% and 100% of the full load; once the sensor data shows that the number of workpieces reaches this range, the control system will automatically issue a command to increase the operating frequency of the fresh air supply fan and the exhaust gas fan from the third preset frequency, such as 40Hz, to a higher fourth preset frequency, such as 50Hz. This is because under conditions close to full load or full load, more workpieces mean more VOC generation and heat demand, and more fresh air is needed to reduce the VOC concentration and maintain the temperature in the furnace, while more exhaust gas is discharged to keep the furnace environment safe and stable; finally, this practice of automatically adjusting the fan frequency according to the actual load can ensure that the drying furnace can operate efficiently under conditions close to full load or full load, which not only ensures production safety, but also optimizes energy use, avoids energy waste, improves overall energy efficiency and production efficiency, and ensures the economy and environmental friendliness of the drying furnace operation.

[0104] Take a 30JPH vehicle drying furnace as an example to calculate the energy saving benefits: Set the fresh air and exhaust gas intake to 15000Nm 3 / h, the drying furnace operating temperature is 160℃, single shift production, energy saving is as follows:

[0105] When the machine is turned on, it takes 90 minutes to reach the temperature. Energy consumption for heating fresh air:

[0106] Q1=1.5*15000m 3 / h*1.2kg / m 3 *0.24(Ka / kg·℃)*(160-20) / 2=450,000 Kcal

[0107] Waste energy consumption:

[0108] Q2=1.5*24000m 3 / h*1.2kg / m 3 *0.24(Ka / kg·℃)*(160-20) / 2=730,000 Kcal

[0109] A total of 1.18 million Kcal, about 148 Nm 3 Natural gas heating, valued at about 500 yuan. Set lunch, dinner, and rest time to about 2 hours in total, exhaust gas is operated at 20HZ, exhaust gas volume is 1 / 4 of full load, fresh air is reduced by 2*15000*3 / 4=22500m 3 (20℃), similarly, the heating energy consumption is 900,000 Kcal, and the exhaust gas reduction is 2*24000*3 / 4=36000m 3 (160℃), similarly, the exhaust gas reduces energy consumption by 1.43 million Kcal, a total of 2.33 million Kcal, about 291Nm 3 Natural gas heating is worth about 980 yuan (the reduction in fan operating frequency and energy saving of exhaust gas incineration equipment are ignored).

[0110] In this embodiment, when the drying furnace is in the startup and heating stage and the number of workpieces is within the first preset load range, the operating frequency of the fresh air supply fan and the exhaust gas fan is adjusted to the first preset frequency; when the drying furnace is in the startup and heating stage and the number of workpieces is within the second preset load range, the operating frequency is adjusted to the second preset frequency, the lowest value of the second preset load range is greater than or equal to the highest value of the first preset load range, and the second preset frequency is greater than the first preset frequency; when the drying furnace is in the startup and heating stage and the number of workpieces is within the third preset load range, the operating frequency is adjusted to the third preset frequency, the lowest value of the third preset load range is greater than or equal to the highest value of the second preset load range, and the third preset frequency is greater than the second preset frequency; when the drying furnace is in the startup and heating stage and the number of workpieces is within the fourth preset load range, the operating frequency is adjusted to the fourth preset frequency, the lowest value of the fourth preset load range is greater than or equal to the highest value of the third preset load range, and the fourth preset frequency is greater than the third preset frequency. The fan control system dynamically adjusts the fan frequency according to the number of workpieces in the drying furnace during the startup and heating stage to optimize energy consumption and production efficiency. When the number of workpieces is small and within the first preset load range, the fan frequency is adjusted to the first preset frequency to reduce energy consumption, because the VOC generation is low at this time, and a large amount of fresh air and exhaust gas emissions are not required. As the number of workpieces increases to the second preset load range, the fan frequency is increased to the second preset frequency to ensure VOC concentration control and furnace environmental safety. When it further increases to the third preset load range, the fan frequency is adjusted to the third preset frequency to accommodate more fresh air demand and exhaust gas emissions. Finally, when it is close to full load or full load, the fan frequency is increased to the fourth preset frequency to ensure efficient production and environmental control. This intelligent adjustment not only saves energy and reduces consumption and energy costs, but also ensures production safety by accurately controlling VOC concentration, while reducing mechanical wear, extending equipment life, and improving overall production efficiency and economic benefits.

[0111] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the exhaust gas emission control method of the drying furnace of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0112] This application also provides a waste gas emission control device for a drying furnace, please refer to Figure 4 , the exhaust gas emission control device of the drying furnace comprises:

[0113] The heating module 10 is used to stop the fresh air supply fan and the exhaust gas fan when the drying furnace is in the startup and heating stage;

[0114] The production module 20 is used to adjust the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces when the drying furnace is in a normal production stage;

[0115] The end module 30 is used to adjust the operating frequency to a first preset frequency or turn off the fresh air supply fan and the exhaust gas fan when the drying furnace is in the end stage of production.

[0116] In one embodiment, the production module 20 is further used to adjust the operating frequency of the fresh air supply fan and the exhaust gas fan to a first preset frequency when the drying furnace is in the startup and heating stage and the number of workpieces is within a first preset load range; when the drying furnace is in the startup and heating stage and the number of workpieces is within a second preset load range, adjust the operating frequency to a second preset frequency, the lowest value of the second preset load range is greater than or equal to the highest value of the first preset load range, and the second preset frequency is greater than the first preset frequency; when the drying furnace is in the startup and heating stage and the number of workpieces is within a third preset load range, adjust the operating frequency to a third preset frequency, the lowest value of the third preset load range is greater than or equal to the highest value of the second preset load range, and the third preset frequency is greater than the second preset frequency; when the drying furnace is in the startup and heating stage and the number of workpieces is within a fourth preset load range, adjust the operating frequency to a fourth preset frequency, the lowest value of the fourth preset load range is greater than or equal to the highest value of the third preset load range, and the fourth preset frequency is greater than the third preset frequency.

[0117] In one embodiment, the production module 20 is also used to obtain the temperature, humidity and volatile organic compound concentration in the drying furnace; when at least one of the temperature is lower than the preset drying temperature range, the humidity is lower than the preset drying humidity range and the volatile organic compound concentration is lower than the preset concentration, the operating frequency is reduced; when at least one of the temperature is higher than the preset drying temperature range, the humidity is greater than the preset drying humidity range and the volatile organic compound concentration is greater than the preset concentration, the operating frequency is increased.

[0118] In one embodiment, the production module 20 is also used to obtain the type and volume of the workpiece; when the type belongs to the first preset type or the volume is smaller than the first preset volume, the operating frequency is adjusted to the first preset frequency range; when the type belongs to the second preset type, the operating frequency is adjusted to the second preset frequency range, the thermal conductivity of the second preset type is weaker than the thermal conductivity of the first preset type, and the lowest value of the second preset frequency range is greater than the highest value of the first preset frequency range; when the type belongs to the third preset type or the volume is larger than the second preset volume, the operating frequency is adjusted to the third preset frequency range, the thermal conductivity of the third preset type is weaker than the thermal conductivity of the second preset type, the lowest value of the third preset frequency range is greater than the highest value of the second preset frequency range, and the second preset volume is larger than the first preset volume.

[0119] In one embodiment, the production module 20 is also used to discharge the exhaust gas into the exhaust gas incineration device through the exhaust gas fan; obtain the concentration of volatile organic compounds in the exhaust gas incineration device; when the concentration of volatile organic compounds is lower than the preset emission concentration threshold, the exhaust gas after incineration is discharged into the exhaust gas waste heat recovery device or into the atmosphere through the exhaust gas fan.

[0120] In one embodiment, the production module 20 is also used to obtain the actual rotational speeds of the fresh air supply fan and the exhaust gas fan; calculate the rotational speed difference based on the operating frequency and the actual rotational speed; and send the basic information of the fan whose rotational speed difference is greater than a preset rotational speed difference threshold and the rotational speed difference as fault information to a preset device.

[0121] In one embodiment, the production module 20 is also used to obtain the pole pairs of the fresh air supply fan and the exhaust gas fan; calculate the theoretical speed according to the operating frequency and the pole pairs; and calculate the speed difference according to the actual speed and the theoretical speed.

[0122] The exhaust gas emission control device for a drying furnace provided in the present application adopts the exhaust gas emission control method for a drying furnace in the above-mentioned embodiment, and can solve the technical problem of how to effectively reduce the energy waste caused by the volatilization of volatile organic compounds in the drying furnace during the heating process. Compared with the prior art, the beneficial effects of the exhaust gas emission control device for a drying furnace provided in the present application are the same as the beneficial effects of the exhaust gas emission control method for a drying furnace provided in the above-mentioned embodiment, and the other technical features of the exhaust gas emission control device for a drying furnace are the same as the features disclosed in the above-mentioned embodiment method, which will not be repeated here.

[0123] The present application provides an exhaust gas emission control device for a drying furnace, the exhaust gas emission control device for the drying furnace comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the exhaust gas emission control method for the drying furnace in the above-mentioned embodiment one.

[0124] Reference below Figure 5 , which shows a schematic diagram of the structure of the exhaust gas emission control device of the drying furnace suitable for implementing the embodiment of the present application. The exhaust gas emission control device of the drying furnace in the embodiment of the present application may include but is not limited to mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), PMPs (Portable Media Players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 5 The exhaust gas emission control device of the drying furnace shown is only an example and should not bring any limitation to the function and scope of use of the embodiments of the present application.

[0125] like Figure 5As shown, the exhaust gas emission control device of the drying furnace may include a processing device 1001 (such as a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the exhaust gas emission control device of the drying furnace are also stored. The processing device 1001, ROM1002 and RAM1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to the I / O interface 1006: input devices 1007 including, for example, a touch screen, a touchpad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; storage devices 1003 including, for example, a magnetic tape, a hard disk, etc.; and communication devices 1009. The communication device 1009 can allow the exhaust gas emission control device of the drying furnace to communicate with other devices wirelessly or by wire to exchange data. Although the exhaust gas emission control device of the drying furnace with various systems is shown in the figure, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems may be implemented or have alternatively.

[0126] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0127] The exhaust gas emission control device for the drying furnace provided in the present application adopts the exhaust gas emission control method for the drying furnace in the above embodiment, which can solve the technical problem of how to effectively reduce the energy waste caused by the volatilization of volatile organic compounds in the drying furnace during the heating process. Compared with the prior art, the beneficial effects of the exhaust gas emission control device for the drying furnace provided in the present application are the same as the beneficial effects of the exhaust gas emission control method for the drying furnace provided in the above embodiment, and the other technical features of the exhaust gas emission control device for the drying furnace are the same as the features disclosed in the method of the previous embodiment, which will not be repeated here.

[0128] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0129] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0130] The present application provides a computer-readable storage medium having computer-readable program instructions (ie, computer programs) stored thereon, and the computer-readable program instructions are used to execute the exhaust gas emission control method of the drying furnace in the above-mentioned embodiment.

[0131] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination of the above.

[0132] The computer-readable storage medium may be included in the exhaust gas emission control device of the drying furnace; or may exist independently without being assembled into the exhaust gas emission control device of the drying furnace.

[0133] The above-mentioned computer-readable storage medium carries one or more programs. When the above-mentioned one or more programs are executed by the exhaust gas emission control device of the drying furnace, the exhaust gas emission control device of the drying furnace: when the drying furnace is in the startup and heating stage, the fresh air supply fan and the exhaust gas fan are stopped; when the drying furnace is in the normal production stage, the operating frequency of the fresh air supply fan and the exhaust gas fan is adjusted according to the number of workpieces; when the drying furnace is in the end of production, the operating frequency is adjusted to the first preset frequency or the fresh air supply fan and the exhaust gas fan are turned off.

[0134] Computer program code for performing the operations of the present application may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0135] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0136] The modules involved in the embodiments described in this application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0137] The readable storage medium provided in the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned method for controlling the exhaust gas emission of the drying furnace, and can solve the technical problem of how to effectively reduce the energy waste caused by the volatilization of volatile organic compounds during the heating process of the drying furnace. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in the present application are the same as the beneficial effects of the method for controlling the exhaust gas emission of the drying furnace provided in the above-mentioned embodiment, and will not be repeated here.

[0138] The present application also provides a computer program product, including a computer program, which implements the steps of the above-mentioned method for controlling exhaust gas emissions from a drying furnace when executed by a processor.

[0139] The computer program product provided in this application can solve the technical problem of how to effectively reduce the energy waste caused by the volatilization of volatile organic compounds during the heating process of the drying furnace. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as the beneficial effects of the exhaust gas emission control method of the drying furnace provided in the above embodiment, which will not be repeated here.

[0140] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A method for controlling waste gas emissions from a drying furnace, characterized in that: The method comprises: When the drying furnace is in the startup and heating stage, stop the fresh air supply fan and the exhaust fan; When the drying furnace is in a normal production stage, the operating frequencies of the fresh air supply fan and the exhaust gas fan are adjusted according to the number of workpieces; When the drying furnace is in the final stage of production, the operating frequency is adjusted to a first preset frequency or the fresh air supply fan and the exhaust gas fan are turned off.

2. The method according to claim 1, characterized in that When the drying furnace is in a normal production stage, the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces includes: When the drying furnace is in the startup and heating stage and the number of workpieces is within the first preset load range, the operating frequency of the fresh air supply fan and the exhaust gas fan is adjusted to the first preset frequency; When the drying furnace is in the startup and heating stage and the number of workpieces is within a second preset load range, the operating frequency is adjusted to a second preset frequency, the lowest value of the second preset load range is greater than or equal to the highest value of the first preset load range, and the second preset frequency is greater than the first preset frequency; When the drying furnace is in the startup and heating stage and the number of workpieces is within a third preset load range, the operating frequency is adjusted to a third preset frequency, the lowest value of the third preset load range is greater than or equal to the highest value of the second preset load range, and the third preset frequency is greater than the second preset frequency; When the drying furnace is in the startup and heating stage and the number of workpieces is within the fourth preset load range, the operating frequency is adjusted to the fourth preset frequency, the lowest value of the fourth preset load range is greater than or equal to the highest value of the third preset load range, and the fourth preset frequency is greater than the third preset frequency.

3. The method according to claim 1, characterized in that When the drying furnace is in a normal production stage, after the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, the method further includes: Obtaining the temperature, humidity and volatile organic compound concentration in the drying oven; When at least one of the following conditions is met: the temperature is lower than a preset drying temperature range, the humidity is lower than a preset drying humidity range, and the concentration of volatile organic compounds is lower than a preset concentration, reducing the operating frequency; When at least one of the following conditions is met: the temperature is higher than the preset drying temperature range, the humidity is higher than the preset drying humidity range, and the concentration of volatile organic compounds is higher than the preset concentration, the operating frequency is increased.

4. The method according to claim 1, characterized in that When the drying furnace is in a normal production stage, after the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, the method further includes: Get the type and volume of the workpiece; When the type belongs to the first preset type or the volume is smaller than the first preset volume, adjusting the operating frequency to a first preset frequency range; When the type belongs to the second preset type, the operating frequency is adjusted to a second preset frequency range, the thermal conductivity of the second preset type is weaker than the thermal conductivity of the first preset type, and the lowest value of the second preset frequency range is greater than the highest value of the first preset frequency range; When the type belongs to the third preset type or the volume is greater than the second preset volume, the operating frequency is adjusted to the third preset frequency range, the thermal conductivity of the third preset type is weaker than the thermal conductivity of the second preset type, the lowest value of the third preset frequency range is greater than the highest value of the second preset frequency range, and the second preset volume is greater than the first preset volume.

5. The method according to claim 1, characterized in that The method further comprises: The waste gas is discharged into the waste gas incineration device through the waste gas fan; Obtaining the concentration of volatile organic compounds in the waste gas incineration device; When the concentration of the volatile organic compounds is lower than a preset emission concentration threshold, the waste gas after incineration is discharged into a waste gas waste heat recovery device or into the atmosphere through the waste gas fan.

6. The method according to claim 1, characterized in that When the drying furnace is in a normal production stage, after the step of adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces, the method further includes: Obtaining actual rotation speeds of the fresh air supply fan and the exhaust gas fan; Calculate the speed difference according to the operating frequency and the actual speed; The basic information of the fan whose speed difference is greater than a preset speed difference threshold and the speed difference are sent to a preset device as fault information.

7. The method according to claim 6, characterized in that The step of calculating the speed difference according to the operating frequency and the actual speed comprises: Obtaining the pole pairs of the fresh air supply fan and the exhaust gas fan; Calculate the theoretical speed according to the operating frequency and the number of pole pairs; A speed difference is calculated according to the actual speed and the theoretical speed.

8. A waste gas emission control device for a drying furnace, characterized in that: The device comprises: The heating module is used to stop the fresh air supply fan and the exhaust gas fan when the drying furnace is in the startup and heating stage; A production module, used for adjusting the operating frequency of the fresh air supply fan and the exhaust gas fan according to the number of workpieces when the drying furnace is in a normal production stage; The end module is used to adjust the operating frequency to a first preset frequency or turn off the fresh air supply fan and the exhaust gas fan when the drying furnace is in the end stage of production.

9. An exhaust gas emission control device for a drying furnace, characterized in that: The device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the method for controlling exhaust gas emissions of a drying furnace according to any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the exhaust gas emission control method of the drying furnace according to any one of claims 1 to 7 are implemented.

Images