Organic fertilizer hot air drying system and automatic control method thereof

Abstract

The application discloses a machine fertilizer hot air drying system, which comprises a batching tank, a feeding pump, a hot air furnace, a drying tower and an atomizer, and further comprises a batching tank pH control unit, a batching tank temperature control unit, a hot air furnace combustion control unit, a drying tower inlet temperature control unit, a drying tower outlet temperature control unit and a drying tower pressure control unit. The application further discloses an automatic control method based on the machine fertilizer hot air drying system. The pH value, temperature and pressure signals are collected by sensors arranged at different positions, compared with the limits set by a PID controller, and control signals are sent to a hand controller to control the working of the execution components. The machine fertilizer hot air drying system and the automatic control method thereof do not need manual operation, have high working efficiency, can improve the production efficiency of the device, stabilize the production process of the whole technology, improve the consistency of products, are suitable for mass production and reduce the production cost of enterprises.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for organic fertilizer drying, and in particular to an organic fertilizer hot air drying system and its automatic control method. Background Technology

[0002] Currently, with the increasing awareness of ecological and environmental protection, the use of organic fertilizers is gradually increasing, while the use of traditional chemical fertilizers is gradually decreasing. The use of organic fertilizers not only increases crop yields but also effectively protects the environment and reduces pollution. The processing of organic fertilizers requires drying the materials. The common process flow for hot air drying systems is as follows: Organic fertilizer raw material liquid is heated in a batching and heating tank with steam to raise the temperature, and alkali solution is added to adjust the pH value. After the raw material liquid is mixed and qualified, it is pumped to the atomizer in the drying tower for atomization drying. Coal and air are fully mixed and burned in a hot air furnace. The hot flue gas from the furnace and cold air are adjusted to a suitable temperature in a hot and cold air mixer and then sent to the drying tower. The atomized organic fertilizer raw material droplets come into contact with the hot air, directly evaporating moisture and drying into powdered organic fertilizer. The powdered organic fertilizer is collected in a powder collection system at the bottom of the drying tower and packaged into a finished product. The exhaust gas from the drying tower flows through a dust collector under the action of an induced draft fan before being discharged into the chimney.

[0003] Drying technology and equipment have developed rapidly in recent years; however, the automation technology of hot air drying equipment lags behind. Most hot air drying equipment uses simple, conventional control based on local instruments or PLCs. While some equipment employs automatic control for certain process stages, the overall control precision is low, failing to achieve full-process automation and still requiring significant human intervention. Therefore, there is an urgent need for an automated control system for hot air drying of organic fertilizer to address these issues.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an organic fertilizer hot air drying system, comprising: a batching tank, a feed pump, a hot air furnace, a drying tower, and an atomizer;

[0006] The ingredient tank is connected to the atomizer installed at the top of the drying tower via the feed pump, and the hot air furnace is connected to the drying tower;

[0007] The mixing tank is equipped with a pH control unit and a temperature control unit; the hot air furnace is equipped with a combustion control unit; and the drying tower is equipped with an inlet temperature control unit, an outlet temperature control unit, and a pressure control unit.

[0008] The pH control unit of the mixing tank includes an online pH meter, a first PID controller, a first handheld device, and an alkali pump. The online pH meter is installed inside the mixing tank. The online pH meter collects pH value signals and uploads them to the first PID controller. The first PID controller is used to set pH value limits, compares the limits with the received pH value signals, and then outputs control signals to the first handheld device. The first handheld device controls the operation of the alkali pump.

[0009] The temperature control unit for the mixing tank includes a thermometer, a second PID controller, a second handheld device, a steam heater, and a heating steam regulating valve. The thermometer and the steam heater are installed inside the mixing tank. The steam heater is connected to the heating steam regulating valve. The thermometer collects temperature signals and uploads them to the second PID controller. The second PID controller is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the second handheld device. The second handheld device controls the operation of the heating steam regulating valve.

[0010] The hot blast stove combustion control unit includes a hot blast stove outlet temperature thermometer, a third PID controller, a third handheld device, a fourth handheld device, a signal distribution module, a multiplier, a coal feeder, and a blower. The hot blast stove has a hot blast stove inlet and an outlet, and the hot blast stove inlet is connected to the blower. The hot blast stove outlet temperature thermometer is located at the hot blast stove outlet. The hot blast stove outlet temperature thermometer collects temperature signals and uploads them to the third PID controller. The third PID controller is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the signal distribution module and the multiplier respectively. The signal distribution module is connected to the third handheld device, which controls the operation of the coal feeder. The multiplier is connected to the fourth handheld device, which controls the operation of the blower.

[0011] The drying tower inlet temperature control unit includes a drying tower inlet thermometer, a fourth PID controller, a fifth handheld device, and a cold air damper. The drying tower has an air inlet connected to the hot air furnace outlet. The drying tower inlet thermometer is located at the air inlet, and the cold air damper is located between the hot air furnace outlet and the drying tower inlet. The drying tower inlet thermometer collects temperature signals and uploads them to the fourth PID controller. The fourth PID controller sets temperature limits, compares the limits with the received temperature signals, and outputs control signals to the fifth handheld device. The fifth handheld device controls the operation of the cold air damper.

[0012] The drying tower outlet temperature control unit includes a drying tower outlet thermometer, a fifth PID controller, and a sixth handheld device. The drying tower has an air outlet, and the drying tower outlet thermometer is located at the air outlet. The drying tower outlet thermometer collects temperature signals and uploads them to the fifth PID controller. The fifth PID controller is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the sixth handheld device. The sixth handheld device controls the operation of the feed pump.

[0013] The drying tower pressure control unit includes a drying tower pressure transmitter, a sixth PID controller, a seventh handheld device, and an induced draft fan. The drying tower has a drying tower outlet, which is connected to the induced draft fan. The drying tower pressure transmitter is installed inside the drying tower. The drying tower pressure transmitter collects pressure signals and uploads them to the sixth PID controller. The sixth PID controller is used to set pressure limits, compares the limits with the received pressure signals, and then outputs control signals to the seventh handheld device. The seventh handheld device controls the operation of the induced draft fan.

[0014] Preferably, the thermometers, hot air furnace outlet temperature thermometers, drying tower inlet temperature thermometers, and drying tower outlet temperature thermometers are resistance thermometers or thermocouple thermometers.

[0015] The present invention also provides an automatic control method based on the above-mentioned organic fertilizer hot air drying system, comprising the following steps:

[0016] Step S1: The pH control unit of the batching tank, the temperature control unit of the batching tank, the combustion control unit of the hot air furnace, the inlet temperature control unit of the drying tower, the outlet temperature control unit of the drying tower, and the pressure control unit of the drying tower all include sensors, PID controllers, handheld devices, and actuators. The sensors acquire the pH value, temperature, and pressure signals at various locations in the organic fertilizer hot air drying system, and all signals are uploaded to the PID controller.

[0017] Step S2: Set the limits for pH value in the batching tank, temperature in the batching tank, outlet temperature of the hot air furnace, inlet temperature of the drying tower, outlet temperature of the drying tower, and pressure in the drying tower in the organic fertilizer hot air drying system using the PID controller.

[0018] In step S3, the PID controller compares the signal acquired in step S1 with the limit value set in step S2, and sends a control signal to the handheld device, which then controls the operation of the actuator.

[0019] In step S1, the pH control unit of the mixing tank includes an online pH meter, a first PID controller, a first handheld device, and an alkaline pump. The online pH meter collects pH value signals and uploads them to the first PID controller.

[0020] In step S2, the pH limit in the mixing tank is set by the first PID controller;

[0021] In step S3, the first PID controller compares the pH value signal collected in step S1 with the limit value set in step S2, and sends a control signal to the first handheld device, which controls the operation of the alkali pump. If the pH value is less than the limit value, the alkali pump pumps the alkali into the mixing tank. If the pH value is greater than the limit value, the alkali pump stops pumping the alkali into the mixing tank.

[0022] In step S1, the temperature control unit of the batching tank includes a thermometer, a second PID controller, a second handheld device, a steam heater, and a heating steam regulating valve; the thermometer and the steam heater are installed inside the batching tank, the steam heater is connected to the heating steam regulating valve, and the thermometer collects temperature signals and uploads them to the second PID controller.

[0023] In step S2, the temperature limit inside the mixing tank is set by the second PID controller;

[0024] In step S3, the second PID controller compares the temperature signal collected in step S1 with the limit value set in step S2, and sends a control signal to the second handheld device, which controls the operation of the heating steam regulating valve. If the temperature is higher than the limit value, the heating steam regulating valve is closed to stop the heating in the batching tank; if the temperature is lower than the limit value, the heating steam regulating valve is opened to heat the batching tank.

[0025] In step S1, the hot blast stove combustion control unit includes a hot blast stove outlet temperature thermometer, a third PID controller, a third handheld device, a fourth handheld device, a signal distribution module, a multiplier, a coal feeder, and a blower; the hot blast stove has a hot blast stove inlet and a hot blast stove outlet, and the hot blast stove inlet is connected to the blower; the hot blast stove outlet temperature thermometer is installed at the hot blast stove outlet, and the hot blast stove outlet temperature thermometer collects temperature signals and uploads them to the third PID controller;

[0026] In step S2, the limit value of the hot air furnace outlet temperature is set by the third PID controller;

[0027] In step S3, the third PID controller compares the temperature signal acquired in step S1 with the limit set in step S2, and then outputs control signals to the signal distribution module and the multiplier respectively. The signal distributor transmits the control signal to the third handheld device, which controls the operation of the coal feeder. The multiplier uses the air volume ratio coefficient to match the signal from the third PID controller, and then outputs a control signal to the fourth handheld device, which controls the blower's air delivery frequency to adjust the air volume. If the temperature is higher than the limit, the coal feeder's coal feed rate and the blower's air delivery rate are reduced; if the temperature is lower than the limit, the coal feeder's coal feed rate and the blower's air delivery rate are increased.

[0028] In step S1, the drying tower inlet temperature control unit includes a drying tower inlet thermometer, a fourth PID controller, a fifth handheld device, and a cold air damper; the drying tower is provided with a drying tower air inlet, which is connected to the hot air furnace outlet; the drying tower inlet thermometer is installed at the drying tower air inlet, and the cold air damper is installed between the hot air furnace outlet and the drying tower air inlet; the drying tower inlet thermometer collects temperature signals and uploads them to the fourth PID controller;

[0029] In step S2, the limit value of the drying tower inlet temperature is set by the fourth PID controller;

[0030] In step S3, the fourth PID controller compares the temperature signal collected in step S1 with the limit set in step S2, and then sends a control signal to the fifth handheld device, which controls the operation of the cold air damper; if the temperature is higher than the limit, the cold air damper is opened; if the temperature is lower than the limit, the cold air damper is closed.

[0031] In step S1, the drying tower outlet temperature control unit includes a drying tower outlet thermometer, a fifth PID controller, and a sixth handheld device; the drying tower is provided with a drying tower air outlet, and the drying tower outlet thermometer is installed at the drying tower air outlet; the drying tower outlet thermometer collects temperature signals and uploads them to the fifth PID controller.

[0032] In step S2, the limit value of the drying tower outlet temperature is set by the fifth PID controller;

[0033] In step S3, the fifth PID controller compares the temperature signal collected in step S1 with the limit value set in step S2, and then sends a control signal to the sixth handheld device, which controls the feeding amount of the feeding pump; if the temperature is higher than the limit value, the feeding amount of the feeding pump is increased; if the temperature is lower than the limit value, the feeding amount of the feeding pump is reduced.

[0034] In step S1, the drying tower pressure control unit includes a drying tower pressure transmitter, a sixth PID controller, a seventh handheld device, and an induced draft fan; the drying tower is provided with a drying tower air outlet, which is connected to the induced draft fan, and the drying tower pressure transmitter is installed inside the drying tower; the drying tower pressure transmitter collects pressure signals and uploads them to the sixth PID controller.

[0035] In step S2, the pressure limit inside the drying tower is set by the sixth PID controller;

[0036] In step S3, the sixth PID controller compares the pressure signal collected in step S1 with the limit value set in step S2, and then sends a control signal to the seventh handheld device, which controls the air volume of the induced draft fan. When the pressure is higher than the limit value, the air volume of the induced draft fan is increased; when the pressure is lower than the limit value, the air volume of the induced draft fan is reduced.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The organic fertilizer hot air drying system and its automatic control method of the present invention require no manual operation, have high working efficiency, can improve the production efficiency of the device, stabilize the entire production process, improve product consistency, are suitable for mass production, and reduce enterprise production costs. Attached Figure Description

[0039] Figure 1 This is a structural diagram of an organic fertilizer hot air drying system.

[0040] Figure 2 This is a structural diagram of the pH control unit for the mixing tank.

[0041] Figure 3 This is a structural diagram of the temperature control unit for the mixing tank.

[0042] Figure 4 This is a structural diagram of the combustion control unit of the hot blast stove.

[0043] Figure 5 This is a structural diagram of the inlet temperature control unit of the drying tower.

[0044] Figure 6 This is a structural diagram of the temperature control unit at the outlet of the drying tower.

[0045] Figure 7 This is a structural diagram of the pressure control unit for the drying tower.

[0046] In the diagram, 1-Battery mixing tank, 2-Feed pump, 3-Hot air furnace, 4-Drying tower, 5-Atomizer, 6-Online pH meter, 7-First PID controller, 8-First handheld controller, 9-Alkali pump, 10-Thermometer, 11-Second PID controller, 12-Second handheld controller, 13-Steam heater, 14-Heating steam regulating valve, 15-Hot air furnace outlet thermometer, 16-Third PID controller, 17-Third handheld controller, 18-Fourth handheld controller. 19-Signal distribution module, 20-Multiplier, 21-Coal feeder, 22-Blower, 23-Drying tower inlet thermometer, 24-Fourth PID controller, 25-Fifth handheld device, 26-Cold air damper, 27-Drying tower outlet thermometer, 28-Fifth PID controller, 29-Sixth handheld device, 30-Drying tower pressure transmitter, 31-Sixth PID controller, 32-Seventh handheld device, 33-Exhaust fan, 34-Dust collector, 35-Chimney. Detailed Implementation

[0047] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0048] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0049] Example 1

[0050] See appendix Figure 1-7 An organic fertilizer hot air drying system includes: a batching tank 1, a feeding pump 2, a hot air furnace 3, a drying tower 4, and an atomizer 5;

[0051] The mixing tank 1 is connected to the atomizer 5 installed at the top of the drying tower 4 via the feed pump 2, and the hot air furnace 3 is connected to the drying tower 4;

[0052] The mixing tank 1 is equipped with a pH control unit and a temperature control unit; the hot air furnace 3 is equipped with a combustion control unit; and the drying tower 4 is equipped with an inlet temperature control unit, an outlet temperature control unit, and a pressure control unit.

[0053] The pH control unit of the mixing tank includes an online pH meter 6, a first PID controller 7, a first handheld device 8, and an alkali pump 9. The online pH meter 6 is installed in the mixing tank 1. The online pH meter 6 collects pH value signals and uploads them to the first PID controller 7. The first PID controller 7 is used to set the pH value limit, compares the limit with the received pH value signal, and then outputs a control signal to the first handheld device 8. The first handheld device 8 controls the operation of the alkali pump 9.

[0054] The temperature control unit for the batching tank includes a thermometer 10, a second PID controller 11, a second handheld device 12, a steam heater 13, and a heating steam regulating valve 14. The thermometer 10 and the steam heater 13 are installed inside the batching tank 1. The steam heater 13 is connected to the heating steam regulating valve 14. The thermometer 10 collects temperature signals and uploads them to the second PID controller 11. The second PID controller 11 is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the second handheld device 12. The second handheld device 12 controls the operation of the heating steam regulating valve 14. Heating steam passes through the heating steam regulating valve 14 and the steam heater 13 to heat the batching tank 1, and then is discharged and enters the condensate recovery system.

[0055] The hot blast stove combustion control unit includes a hot blast stove outlet temperature thermometer 15, a third PID controller 16, a third handheld device 17, a fourth handheld device 18, a signal distribution module 19, a multiplier 20, a coal feeder 21, and a blower 22. The hot blast stove 3 has a hot blast stove inlet and a hot blast stove outlet, and the hot blast stove inlet is connected to the blower 22. The hot blast stove outlet temperature thermometer 15 is located at the hot blast stove outlet. The hot blast stove outlet temperature thermometer 15 collects temperature signals and uploads them to the third PID controller 16. The third PID controller 16 is used to set temperature limits and compares the limits with the received temperature signals before outputting control signals to the signal distribution module 19 and the multiplier 20 respectively. The signal distribution module 19 is connected to the third handheld device 17, which controls the operation of the coal feeder 21. The multiplier 20 is connected to the fourth handheld device 18, which controls the operation of the blower 22.

[0056] The drying tower inlet temperature control unit includes a drying tower inlet thermometer 23, a fourth PID controller 24, a fifth handheld device 25, and a cold air damper 26. The drying tower 4 is equipped with a drying tower air inlet, which is connected to the hot air furnace outlet. The drying tower inlet thermometer 23 is located at the drying tower air inlet, and the cold air damper 26 is located between the hot air furnace outlet and the drying tower air inlet. The drying tower inlet thermometer 23 collects temperature signals and uploads them to the fourth PID controller 24. The fourth PID controller 24 is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the fifth handheld device 25. The fifth handheld device 25 controls the operation of the cold air damper 26.

[0057] The drying tower outlet temperature control unit includes a drying tower outlet thermometer 27, a fifth PID controller 28, and a sixth handheld device 29. The drying tower 4 is equipped with a drying tower outlet. The drying tower outlet thermometer 27 is installed at the drying tower outlet. The drying tower outlet thermometer 27 collects temperature signals and uploads them to the fifth PID controller 28. The fifth PID controller 28 is used to set temperature limits and compares the limits with the received temperature signals before outputting control signals to the sixth handheld device 29. The sixth handheld device 29 controls the operation of the feed pump 2.

[0058] The drying tower pressure control unit includes a drying tower pressure transmitter 30, a sixth PID controller 31, a seventh handheld device 32, and an induced draft fan 33. The drying tower 4 is equipped with a drying tower air outlet, which is connected to the induced draft fan 33. The drying tower pressure transmitter 30 is installed inside the drying tower 4. The drying tower pressure transmitter 30 collects pressure signals and uploads them to the sixth PID controller 31. The sixth PID controller 31 is used to set pressure limits, compares the limits with the received pressure signals, and then outputs control signals to the seventh handheld device 32. The seventh handheld device 32 controls the operation of the induced draft fan 33. The air inside the drying tower 4 is discharged by the induced draft fan 33, and then discharged outdoors through the dust collector 34 and the chimney 35.

[0059] Among them, thermometer 10, hot air furnace outlet temperature thermometer 15, drying tower inlet temperature thermometer 23, and drying tower outlet temperature thermometer 27 are resistance thermometers.

[0060] The automatic control method for the above-mentioned organic fertilizer hot air drying system includes the following steps:

[0061] Step S1: The pH control unit of the batching tank, the temperature control unit of the batching tank, the combustion control unit of the hot air furnace, the inlet temperature control unit of the drying tower, the outlet temperature control unit of the drying tower, and the pressure control unit of the drying tower all include sensors, PID controllers, handheld devices, and actuators. The sensors acquire the pH value, temperature, and pressure signals at various locations in the organic fertilizer hot air drying system, and all signals are uploaded to the PID controller.

[0062] Step S2: Set the limits for pH value in the batching tank, temperature in the batching tank, outlet temperature of the hot air furnace, inlet temperature of the drying tower, outlet temperature of the drying tower, and pressure in the drying tower in the organic fertilizer hot air drying system using the PID controller.

[0063] In step S3, the PID controller compares the signal acquired in step S1 with the limit value set in step S2, and sends a control signal to the handheld device, which then controls the operation of the actuator.

[0064] See Appendix Figure 2 The automatic control method for the pH control unit of the mixing tank is as follows:

[0065] In step S1, the online pH meter 6 collects the pH value signal and uploads it to the first PID controller 7;

[0066] In step S2, the pH limit in the mixing tank 1 is set by the first PID controller 7;

[0067] In step S3, the first PID controller 7 compares the pH value signal collected in step S1 with the limit value set in step S2, and sends a control signal to the first handheld device 8, which controls the operation of the alkali pump 9. If the pH value is less than the limit value, the alkali pump 9 pumps the alkali into the mixing tank 1. If the pH value is greater than the limit value, the alkali pump 9 stops pumping the alkali into the mixing tank 1.

[0068] See Appendix Figure 3 The automatic control method for the temperature control unit of the batching tank is as follows:

[0069] In step S1, the thermometer 10 collects the temperature signal and uploads it to the second PID controller 11;

[0070] In step S2, the temperature limit inside the mixing tank 1 is set by the second PID controller 11;

[0071] In step S3, the second PID controller 11 compares the temperature signal collected in step S1 with the limit value set in step S2, and sends a control signal to the second handheld device 12, which controls the operation of the heating steam regulating valve 14. If the temperature is higher than the limit value, the heating steam regulating valve 14 is closed to stop the heating in the batching tank 1; if the temperature is lower than the limit value, the heating steam regulating valve 14 is opened to heat the batching tank 1.

[0072] See Appendix Figure 4 The automatic control method of the hot blast stove combustion control unit is as follows:

[0073] In step S1, the hot air furnace outlet temperature thermometer 15 collects the temperature signal and uploads it to the third PID controller 16;

[0074] In step S2, the limit value of the hot air furnace outlet temperature is set by the third PID controller 16;

[0075] In step S3, the third PID controller 16 compares the temperature signal acquired in step S1 with the limit value set in step S2, and then outputs control signals to the signal distribution module 19 and the multiplier 20 respectively; the signal distribution module 19 transmits the control signal to the third handheld device 17, which controls the operation of the coal feeder 21; the multiplier 20 uses the air volume ratio coefficient to match the signal transmitted from the third PID controller 16, and then outputs a control signal to the fourth handheld device 18, which controls the air delivery frequency of the blower 22 to adjust the air delivery volume; if the temperature is higher than the limit value, the coal feed rate of the coal feeder 21 and the air delivery volume of the blower 22 are reduced; if the temperature is lower than the limit value, the coal feed rate of the coal feeder 21 and the air delivery volume of the blower 22 are increased.

[0076] Please refer to the appendix for details. Figure 5 The automatic control method for the inlet temperature control unit of the drying tower is as follows:

[0077] In step S1, the temperature signal collected by the inlet thermometer 23 of the drying tower is uploaded to the fourth PID controller 24;

[0078] In step S2, the limit value of the inlet temperature of the drying tower 4 is set by the fourth PID controller 24;

[0079] In step S3, the fourth PID controller 24 compares the temperature signal collected in step S1 with the limit value set in step S2, and then sends a control signal to the fifth handheld device 25, which controls the operation of the cooling damper 26; if the temperature is higher than the limit value, the cooling damper 26 is opened; if the temperature is lower than the limit value, the cooling damper 26 is closed.

[0080] Please refer to the appendix for details. Figure 6 The automatic control method for the drying tower outlet temperature control unit is as follows:

[0081] In step S1, the temperature signal collected by the drying tower outlet thermometer 27 is uploaded to the fifth PID controller 28;

[0082] In step S2, the limit value of the outlet temperature of drying tower 4 is set by the fifth PID controller 28;

[0083] In step S3, the fifth PID controller 28 compares the temperature signal collected in step S1 with the limit value set in step S2, and then sends a control signal to the sixth hand controller 29, which controls the feeding amount of the feeding pump 2. If the temperature is higher than the limit value, the feeding amount of the feeding pump 2 is increased; if the temperature is lower than the limit value, the feeding amount of the feeding pump 2 is reduced.

[0084] Please refer to the appendix for details. Figure 7 The automatic control method for the drying tower pressure control unit is as follows:

[0085] In step S1, the drying tower pressure transmitter 30 collects the pressure signal and uploads it to the sixth PID controller 31;

[0086] In step S2, the pressure limit inside the drying tower 4 is set by the sixth PID controller 31;

[0087] In step S3, the sixth PID controller 31 compares the pressure signal collected in step S1 with the limit value set in step S2, and then sends a control signal to the seventh hand controller 32, which controls the air volume of the induced draft fan 33; when the pressure is higher than the limit value, the air volume of the induced draft fan 33 is increased; when the pressure is lower than the limit value, the air volume of the induced draft fan 33 is reduced.

[0088] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An organic fertilizer hot air drying system, characterized in that, include: Ingredient tanks, feed pumps, hot air furnaces, drying towers, and atomizers; The ingredient tank is connected to the atomizer installed at the top of the drying tower via the feed pump, and the hot air furnace is connected to the drying tower; The mixing tank is equipped with a pH control unit and a temperature control unit; the hot air furnace is equipped with a combustion control unit; and the drying tower is equipped with an inlet temperature control unit, an outlet temperature control unit, and a pressure control unit. The hot blast stove combustion control unit includes a hot blast stove outlet temperature thermometer, a third PID controller, a third handheld device, a fourth handheld device, a signal distribution module, a multiplier, a coal feeder, and a blower. The hot blast stove has a hot blast stove inlet and an outlet, and the hot blast stove inlet is connected to the blower. The hot blast stove outlet temperature thermometer is located at the hot blast stove outlet. The hot blast stove outlet temperature thermometer collects temperature signals and uploads them to the third PID controller. The third PID controller is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the signal distribution module and the multiplier respectively. The signal distribution module is connected to the third handheld device, which controls the operation of the coal feeder. The multiplier is connected to the fourth handheld device, which controls the operation of the blower.

2. The organic fertilizer hot air drying system according to claim 1, characterized in that: The pH control unit of the mixing tank includes an online pH meter, a first PID controller, a first handheld device, and an alkali pump. The online pH meter is installed inside the mixing tank. The online pH meter collects pH value signals and uploads them to the first PID controller. The first PID controller is used to set pH value limits, compare the limits with the received pH value signals, and then output a control signal to the first handheld device. The first handheld device controls the operation of the alkali pump. The temperature control unit for the mixing tank includes a thermometer, a second PID controller, a second handheld device, a steam heater, and a heating steam regulating valve. The thermometer and the steam heater are installed inside the mixing tank. The steam heater is connected to the heating steam regulating valve. The thermometer collects temperature signals and uploads them to the second PID controller. The second PID controller is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the second handheld device. The second handheld device controls the operation of the heating steam regulating valve.

3. The organic fertilizer hot air drying system according to claim 1, characterized in that: The drying tower inlet temperature control unit includes a drying tower inlet thermometer, a fourth PID controller, a fifth handheld device, and a cold air damper. The drying tower has an air inlet, which is connected to the hot air furnace outlet. The drying tower inlet thermometer is located at the air inlet, and the cold air damper is located between the hot air furnace outlet and the drying tower inlet. The drying tower inlet thermometer collects temperature signals and uploads them to the fourth PID controller. The fourth PID controller is used to set temperature limits, compares the limits with the received temperature signals, and then outputs a control signal to the fifth handheld device. The fifth handheld device controls the operation of the cold air damper.

4. The organic fertilizer hot air drying system according to claim 1, characterized in that: The drying tower outlet temperature control unit includes a drying tower outlet thermometer, a fifth PID controller, and a sixth handheld device. The drying tower is provided with a drying tower air outlet. The drying tower outlet thermometer is installed at the drying tower air outlet. The drying tower outlet thermometer collects temperature signals and uploads them to the fifth PID controller. The fifth PID controller is used to set temperature limits, compares the limits with the received temperature signals, and then outputs control signals to the sixth handheld device. The sixth handheld device controls the operation of the feed pump. The drying tower pressure control unit includes a drying tower pressure transmitter, a sixth PID controller, a seventh handheld device, and an induced draft fan. The drying tower has a drying tower outlet, which is connected to the induced draft fan. The drying tower pressure transmitter is installed inside the drying tower. The drying tower pressure transmitter collects pressure signals and uploads them to the sixth PID controller. The sixth PID controller is used to set pressure limits, compares the limits with the received pressure signals, and then outputs control signals to the seventh handheld device. The seventh handheld device controls the operation of the induced draft fan.

5. An automatic control method for the organic fertilizer hot air drying system according to any one of claims 1-4, characterized in that, Includes the following steps: Step S1: The pH control unit of the batching tank, the temperature control unit of the batching tank, the combustion control unit of the hot air furnace, the inlet temperature control unit of the drying tower, the outlet temperature control unit of the drying tower, and the pressure control unit of the drying tower all include sensors, PID controllers, handheld devices, and actuators. The sensors acquire the pH value, temperature, and pressure signals at various locations in the organic fertilizer hot air drying system, and all signals are uploaded to the PID controller. Step S2: Set the limits for pH value in the batching tank, temperature in the batching tank, outlet temperature of the hot air furnace, inlet temperature of the drying tower, outlet temperature of the drying tower, and pressure in the drying tower in the organic fertilizer hot air drying system using the PID controller. In step S3, the PID controller compares the signal acquired in step S1 with the limit value set in step S2, and sends a control signal to the handheld device, which then controls the operation of the actuator.

6. The automatic control method according to claim 5, characterized in that: In step S1, the pH control unit of the mixing tank includes an online pH meter, a first PID controller, a first handheld device, and an alkali pump. The online pH meter collects pH value signals and uploads them to the first PID controller. In step S2, the first PID controller sets the pH limit value in the mixing tank. In step S3, the first PID controller compares the pH value signal collected in step S1 with the limit value set in step S2 and sends a control signal to the first handheld device, which then controls the operation of the alkali pump. If the pH value is less than the limit value, the alkali pump pumps alkali into the mixing tank; if the pH value is greater than the limit value, the alkali pump stops pumping alkali into the mixing tank. In step S1, the temperature control unit for the mixing tank includes a thermometer, a second PID controller, a second handheld device, a steam heater, and a heating steam regulating valve. The thermometer and steam heater are installed inside the mixing tank, and the steam heater is connected to the heating steam regulating valve. The thermometer collects temperature signals and uploads them to the second PID controller. In step S2, the temperature limit inside the mixing tank is set by the second PID controller. In step S3, the second PID controller compares the temperature signal collected in step S1 with the limit set in step S2 and sends a control signal to the second handheld device, which controls the operation of the heating steam regulating valve. If the temperature is higher than the limit, the heating steam regulating valve is closed to stop heating inside the mixing tank; if the temperature is lower than the limit, the heating steam regulating valve is opened to heat inside the mixing tank.

7. The automatic control method according to claim 5, characterized in that: In step S1, the hot blast stove combustion control unit includes a hot blast stove outlet temperature thermometer, a third PID controller, a third handheld device, a fourth handheld device, a signal distribution module, a multiplier, a coal feeder, and a blower; the hot blast stove has a hot blast stove inlet and a hot blast stove outlet, and the hot blast stove inlet is connected to the blower; the hot blast stove outlet temperature thermometer is installed at the hot blast stove outlet, and the hot blast stove outlet temperature thermometer collects temperature signals and uploads them to the third PID controller; In step S2, the limit value of the hot air furnace outlet temperature is set by the third PID controller; In step S3, the third PID controller compares the temperature signal collected in step S1 with the limit value set in step S2, and then outputs control signals to the signal distribution module and the multiplier respectively. The signal distributor transmits control signals to the third handheld controller, which controls the operation of the coal feeder. The multiplier uses the air volume ratio coefficient to match the signal from the third PID controller, and then outputs a control signal to the fourth handheld controller, which controls the blower's air delivery frequency to adjust the air volume. If the temperature is higher than the limit, the coal feeder's coal feed rate and the blower's air delivery rate are reduced; if the temperature is lower than the limit, the coal feeder's coal feed rate and the blower's air delivery rate are increased.

8. The automatic control method according to claim 5, characterized in that: In step S1, the drying tower inlet temperature control unit includes a drying tower inlet thermometer, a fourth PID controller, a fifth handheld device, and a cold air damper; the drying tower is provided with a drying tower air inlet, which is connected to the hot air furnace outlet; the drying tower inlet thermometer is installed at the drying tower air inlet, and the cold air damper is installed between the hot air furnace outlet and the drying tower air inlet; the drying tower inlet thermometer collects temperature signals and uploads them to the fourth PID controller; In step S2, the limit value of the drying tower inlet temperature is set by the fourth PID controller; In step S3, the fourth PID controller compares the temperature signal collected in step S1 with the limit set in step S2, and then sends a control signal to the fifth handheld device, which controls the operation of the cold air damper; if the temperature is higher than the limit, the cold air damper is opened; if the temperature is lower than the limit, the cold air damper is closed.

9. The automatic control method according to claim 5, characterized in that: In step S1, the drying tower outlet temperature control unit includes a drying tower outlet thermometer, a fifth PID controller, and a sixth handheld device; the drying tower is provided with a drying tower air outlet, and the drying tower outlet thermometer is installed at the drying tower air outlet; the drying tower outlet thermometer collects temperature signals and uploads them to the fifth PID controller. In step S2, the limit value of the drying tower outlet temperature is set by the fifth PID controller; In step S3, the fifth PID controller compares the temperature signal collected in step S1 with the limit value set in step S2, and then sends a control signal to the sixth handheld device, which controls the feeding amount of the feeding pump; if the temperature is higher than the limit value, the feeding amount of the feeding pump is increased; if the temperature is lower than the limit value, the feeding amount of the feeding pump is reduced.

10. The automatic control method according to claim 5, characterized in that: In step S1, the drying tower pressure control unit includes a drying tower pressure transmitter, a sixth PID controller, a seventh handheld device, and an induced draft fan; the drying tower is provided with a drying tower air outlet, which is connected to the induced draft fan, and the drying tower pressure transmitter is installed inside the drying tower; the drying tower pressure transmitter collects pressure signals and uploads them to the sixth PID controller. In step S2, the pressure limit inside the drying tower is set by the sixth PID controller; In step S3, the sixth PID controller compares the pressure signal collected in step S1 with the limit value set in step S2, and then sends a control signal to the seventh handheld device, which controls the air volume of the induced draft fan. When the pressure is higher than the limit value, the air volume of the induced draft fan is increased; when the pressure is lower than the limit value, the air volume of the induced draft fan is reduced.

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