Low-odor, high-efficiency silkworm excrement drying system

Abstract

This invention discloses a low-odor, high-efficiency drying system for silkworm excrement. Addressing the problems of material clumping, uneven drying, odor escape, high energy consumption, and difficulty in determining the drying endpoint in existing silkworm excrement drying methods, this system employs a multi-layered, thin-layered, breathable support frame within the drying chamber. Each layer of the frame is rigidly fixed as a whole and elastically supported by the chamber wall. Two vibrating motors installed on both sides of the bottom of the lowest frame drive continuous micro-vibration to prevent clumping. A three-layered, graded air inlet is used, with fresh air distributed in a 3:2:1 ratio (lower, middle, upper) via an airflow distribution valve. Hot air penetrates the material layer and exits through the exhaust vent at the top of the chamber, then enters a plate heat exchanger via a one-way valve for preheating. After preheating, the air is heated by a hot air generator and sent to the main air inlet. After cooling, the exhaust air passes through a composite filter of activated carbon and mulberry leaf fiber to absorb odors. Moisture content and dual-channel temperature sensor signals are sent to a temperature controller to adjust the hot air output. This system is primarily used for drying silkworm excrement but is also suitable for drying other wet and sticky materials.

Description

Technical Field

[0001] This invention belongs to the field of material drying and waste gas treatment technology. More specifically, this invention relates to a low-odor and high-efficiency drying system for silkworm excrement. Background Technology

[0002] Silkworm excrement is a major byproduct of silkworm rearing. It has a high moisture content and contains undigested mulberry leaf residue and silkworm metabolites. When piled up, it easily heats up and deteriorates, requiring timely drying for storage or later use. Current drying methods mostly employ static spreading or simple hot air circulation drying. However, because fresh silkworm excrement is sticky, has short fibers, and a high sugar content, the particles easily stick together during heating, forming hard lumps of varying sizes. Once agglomeration occurs, the hot air channels within the material layer are blocked, preventing moisture from escaping smoothly. This results in an over-dry surface while the interior remains highly moist, leading to a highly uneven final moisture content throughout the batch. Breaking up the lumps often requires frequent manual turning of the material, which is labor-intensive and easily damages the particle integrity, causing severe fragmentation.

[0003] The gases released during the drying process of silkworm excrement have a strong, pungent odor. Conventional drying equipment typically discharges these waste gases directly into the atmosphere or only performs simple collection before discharging, causing significant odor pollution to the work area and surrounding environment. While using a closed-loop hot air circulation system can reduce leakage, it also leads to a decrease in drying efficiency due to moisture accumulation. How to balance moisture removal with controlling odor emissions has become a design dilemma.

[0004] In terms of airflow organization, single-point or single-layer air supply methods are difficult to adapt to the gradual water loss of silkworm excrement from top to bottom during the drying process. The materials at different heights are in different drying stages, and their requirements for air temperature and air volume vary. Uniform air supply parameters can easily lead to problems such as the lower layer being too dry while the upper layer remains wet, or the lower layer having insufficient heat while the upper layer is not dehumidified in time, affecting the overall production capacity and the quality of the dried product.

[0005] Furthermore, determining the drying endpoint often relies on operator experience, depending on feel or a fixed drying time to decide whether to discharge the material. The lack of online feedback on material moisture content makes it easy for insufficient drying to lead to mold growth during storage, and for over-drying to waste energy and generate excessive powder. Although contact-based moisture content detection methods exist for online measurement, the problem of material adhering to the probe surface is particularly prominent in the high-humidity, high-viscosity silkworm excrement environment, affecting the continuous accuracy of readings and making it difficult to reliably implement automatic temperature and airflow control based on real-time moisture content. Summary of the Invention

[0006] One object of the present invention is to address at least the aforementioned deficiencies and to provide at least the advantages that will be described later.

[0007] This invention provides a low-odor, high-efficiency drying system for silkworm excrement. Under the continuous micro-vibration of a multi-layered, thin-layered, breathable support frame, it breaks down the adhesion between silkworm excrement particles, preventing material clumping and maintaining unobstructed hot air flow. Utilizing a proportionally distributed three-stage air intake and top-directed exhaust, it takes advantage of the varying air requirements of each layer at different drying stages to ensure consistent drying processes between layers. Simultaneously, the exhaust air is first treated by a gas-to-gas plate heat exchanger to recover waste heat before being sent to an odor-absorbing module, achieving a balance between dehumidification, energy saving, and low-odor emissions. Through the coordinated control of a probe-type moisture content sensor and dual-channel temperature sensors, the drying endpoint is determined online, reducing over-drying and under-drying, and improving the uniformity of the dried product and the system's thermal efficiency.

[0008] This invention provides a low-odor, high-efficiency drying system for silkworm excrement, comprising: The drying chamber has insulation layers on its side walls and top. The multi-layer thin-layer breathable load-bearing mesh frame is fixed to each other by rigid connectors to form a whole. The whole is connected to the inner wall of the drying chamber by elastic support. Silkworm excrement is manually laid on the thin-layer breathable load-bearing mesh frame. The vibration anti-caking component includes two vibration motors, which are symmetrically installed on both sides of the bottom of the lowest thin-layer breathable load-bearing mesh frame. The graded air supply directional airflow system includes a three-layer graded air inlet, a top directional exhaust outlet, a one-way valve, an air-to-air plate heat exchanger, and a hot air generator. The three-layer graded air inlets are distributed sequentially along the lower, middle, and upper parts of the drying chamber. The lower air inlet is located below the lowest thin-layer permeable support frame, the middle air inlet is located below the middle layer of the multi-layer thin-layer permeable support frame, and the upper air inlet is located below the uppermost thin-layer permeable support frame. The fresh air supply ratio of the three-layer graded air inlets to the lower, middle, and upper parts is 3:2:1. This ratio is achieved by the airflow distribution valve located at the total air inlet end of the three-layer graded air inlets. The top directional exhaust outlet is located at the top of the drying chamber. The exhaust air from the top directional exhaust outlet enters the air-to-air plate heat exchanger for heat release through the one-way valve. The fresh air is preheated by the air-to-air plate heat exchanger and then heated by the hot air generator before being sent to the total air inlet end of the three-layer graded air inlets. The odor adsorption module is connected to the exhaust channel outlet of the gas-gas plate heat exchanger and uses a composite filter of activated carbon and mulberry leaf fiber. The intelligent temperature control system with dual linkage between moisture content and temperature includes a moisture content sensor, dual temperature sensors, and a temperature controller. The temperature controller is electrically connected to the moisture content sensor, the dual temperature sensors, and the hot air generator.

[0009] The silkworm excrement in this invention can be manually and evenly spread on a multi-layered, thin-layered, breathable support frame. Each layer of the frame is fixed as a whole by rigid connectors and then installed in the drying chamber via elastic supports. Two vibrating motors are symmetrically installed at the bottom of the lowest frame, driving the entire frame assembly to vibrate continuously at small amplitudes. This prevents the wet, sticky silkworm excrement particles from sticking together, maintaining the gaps for hot air flow. Hot air generated by the hot air generator is distributed to the three-layered air inlets in a 3:2:1 ratio (lower, middle, upper) via the airflow distribution valve at the main air inlet, and is fed into the corresponding material layer from below the frame. This decreasing ratio allows for airflow replenishment to each layer at different drying stages, ensuring each layer receives an appropriate through-layer airflow velocity. The evaporated water vapor is carried to the top of the chamber by the rising airflow. The top directional exhaust vent directs the hot, humid gas into an air-to-air plate heat exchanger to release heat, preheating the newly entering cold air. The cooled exhaust air continues to flow through an activated carbon and mulberry leaf fiber composite filter to remove odor components before being discharged. Signals from the moisture content sensor and dual-channel temperature sensor are sent to the temperature controller, which adjusts the output of the hot air generator accordingly. Drying stops when the moisture content of the top layer of material reaches the set value. This process simultaneously suppresses agglomeration, balances the drying degree between layers, reduces odor escape, and utilizes the waste heat from the exhaust air during continuous drying.

[0010] Preferably, the vibration frequency of the vibrating motor is 15Hz to 30Hz, and the amplitude is 0.5mm to 2.0mm; the moisture content sensor is a probe-type sensor, which is fixed to the upper surface of the uppermost thin-layer breathable support mesh frame by a bracket and inserted into the interior of the silkworm excrement layer, using the state of the uppermost material as the basis for determining the drying endpoint; dual temperature sensors are respectively installed at the total air inlet of the three-layer graded air inlet and 10cm to 20cm above the uppermost silkworm excrement layer inside the drying chamber, for linkage control of hot air output.

[0011] The vibrating motor of this invention operates at a frequency of 15Hz to 30Hz and an amplitude of 0.5mm to 2.0mm, driving a multi-layer mesh frame to continuously vibrate at small amplitudes and high frequencies. This prevents stable adhesion between silkworm excrement particles, keeping the material layer loose and breathable. A probe for moisture content detection is fixed to the upper surface of the top mesh frame via a bracket and inserted into the silkworm excrement layer to sense the moisture content of the top layer in real time. Since the top layer is located at the end of the air path and is dried last, its moisture content is used as the basis for determining the drying endpoint, reflecting whether the entire batch of material has reached the target dryness. Two temperature sensors are installed at the main air inlet and 10cm to 20cm above the top silkworm excrement layer, respectively. The temperature difference measured by the two sensors changes regularly as the material gradually dries. The temperature controller adjusts the output heat and airflow of the hot air generator based on this temperature difference signal, matching the heating supply with the actual dehumidification needs of the material.

[0012] Preferably, the dual-linkage intelligent temperature control system for moisture content and temperature further includes a pulse heating self-cleaning module. This module comprises a miniature heating wire embedded inside the moisture content sensor probe and a timing trigger unit located in the temperature controller. The miniature heating wire contacts the outer surface of the probe through an insulating thermally conductive layer. The timing trigger unit outputs a pulse current to the miniature heating wire at preset time intervals, lasting 0.1 to 0.5 seconds, causing the probe surface temperature to instantly rise to 70°C to 90°C. Subsequently, the adhering layer peels off under the combined action of natural cooling and vibration generated by the vibration motor. When the timing trigger unit outputs the pulse current, the temperature controller automatically pauses the acquisition of the moisture content sensor's detection signal. After the pulse ends and the probe naturally cools to the temperature inside the drying chamber, the temperature controller resumes normal acquisition.

[0013] The moisture content sensor probe of this invention has a miniature heating wire embedded inside, which is thermally connected to the probe's outer surface through an insulating thermally conductive layer. A timing trigger unit in the temperature controller outputs a pulse current for 0.1 to 0.5 seconds at preset time intervals to the heating wire, causing the probe surface temperature to instantly rise to 70°C to 90°C. The thin layer of dirt adhering to the probe surface loses moisture and undergoes thermal stress cracking upon rapid heating. This temperature is lower than the coking temperature of silkworm excrement organic matter, causing only dehydration and embrittlement of the adhering layer without producing a burnt odor. Subsequently, under the combined action of the probe's natural cooling and contraction, and the continuous micro-amplitude mechanical vibration from the mesh frame vibration motor, the dirt peels off the probe surface. During pulse heating and subsequent cooling, the temperature controller pauses the acquisition of the moisture content detection signal, resuming normal measurement after the probe temperature returns to the chamber temperature level, thus avoiding moisture content reading distortion caused by probe self-heating and surface dirt drying. Although the temperature rise caused by pulse heating is reduced when the temperature inside the chamber is high in the later stage of drying, it can still effectively remove most of the deposits on the probe surface when combined with the mechanical peeling action continuously transmitted by the vibration motor.

[0014] Preferably, the temperature controller is also equipped with an airflow settling self-cleaning program. This program is triggered at preset time intervals. Each time it is triggered, the temperature controller outputs a speed reduction command to the hot air generator, reducing the fan speed of the hot air generator to 10% to 20% of its rated speed within 5 to 10 seconds, and maintaining this low speed for 5 to 30 seconds. During the execution of the airflow settling self-cleaning program, the operating status of the vibration motor remains unchanged. During the speed reduction, the acquisition of the detection signal from the moisture content sensor is suspended, the temperature controller suspends the linkage control based on the dual-channel temperature sensor, and the heating power switches to a power reduction protection mode, which is independently controlled by the airflow settling self-cleaning program. Only the signal from the main air inlet temperature sensor is retained for over-temperature protection. After the low speed maintenance ends, the temperature controller restores the rated speed of the hot air generator and the normal acquisition of the moisture content sensor, and resumes the linkage control based on the dual-channel temperature sensor. The preset time interval is 10 to 30 minutes.

[0015] The preset airflow settling self-cleaning program in the temperature controller is automatically triggered every 10 to 30 minutes. Upon triggering, the controller sends a command to the hot air generator, causing the fan speed to gradually decrease to 10% to 20% of its rated speed within 5 to 10 seconds. This sudden reduction in airflow causes the fine dust and debris that were originally suspended above the material layer and between the mesh frame openings to lose the lifting force of the rising airflow and settle back to the surface of the material layer or below the mesh frame under their own gravity. This reduces the tendency for these particles to be repeatedly stirred up in the circulating airflow within the silo and adhere to the duct walls and mesh frame wires. During the deceleration period, the vibrating motor continues to run, and the mesh frame maintains slight vibration, which helps the settled material to redistribute and spread evenly. Simultaneously, the controller suspends signal acquisition from the moisture content sensor and the linkage adjustment based on the dual-channel temperature sensor to prevent short-term temperature fluctuations within the silo from causing drift in the detection values ​​through material conduction. The heating power is then independently controlled by this self-cleaning program, retaining only the temperature signal at the main air inlet for over-temperature protection to prevent localized overheating due to the sudden drop in airflow. Once the low-speed maintenance period ends and the fan returns to its rated speed, the moisture content detection and normal temperature linkage control will resume normal operation.

[0016] Preferably, the hot air generating device includes a fan and a heater, and the temperature controller is also connected to the power control terminal of the heater; when the airflow settling self-cleaning program is triggered, the temperature controller simultaneously outputs a speed reduction command and a heat reduction command to the hot air generating device, wherein the heat reduction command reduces the power of the heater to 10% to 20% of the rated power or shuts it off completely during the fan speed reduction period; and 2 to 5 seconds before the fan speed recovers, the temperature controller first outputs a preheating command to the heater to restore the heater power to the level before the speed reduction, and then outputs a speed increase command to the fan to restore the rated speed.

[0017] Preferably, the temperature controller is further equipped with a vibration adaptive adjustment module. This module connects to two vibration motors via a frequency converter and can adjust the vibration frequency and phase angle difference, with an initial phase angle difference of 0°. The vibration adaptive adjustment module is electrically connected to both the dual-channel temperature sensors and the frequency converter control terminals of the vibration motors. The module calculates in real-time the temperature difference between the total inlet temperature of the dual-channel temperature sensors and the temperature above the silkworm excrement layer, and adjusts the vibration frequency of the vibration motors according to the rate of change of the temperature difference when the airflow settling self-cleaning procedure is not executed, based on the following rules: When the rate of increase of the temperature difference exceeds the first preset threshold, the vibration adaptive adjustment module will reduce the vibration frequency to 15Hz to 20Hz while keeping the amplitude unchanged. When the rate of decrease of the temperature difference exceeds the second preset threshold, the vibration adaptive adjustment module will increase the vibration frequency to 25Hz to 30Hz while keeping the amplitude unchanged. When the rate of increase of the temperature difference does not exceed the first preset threshold and the rate of decrease does not exceed the second preset threshold, the vibration frequency remains at the current value. The first preset threshold is a threshold for the rate of increase of temperature difference, with a value range of 0.5℃ / min to 2.0℃ / min; the second preset threshold is a threshold for the rate of decrease of temperature difference, with a value range of 0.5℃ / min to 2.0℃ / min.

[0018] The vibration adaptive adjustment module is connected to two vibration motors via a frequency converter, enabling independent adjustment of the vibration frequency. The initial phase angle difference is set to 0°. During the normal drying stage, when the airflow settling self-cleaning process is not executed, the module continuously receives signals from the temperature sensor at the main air inlet and the temperature sensor above the silkworm excrement layer, calculating the temperature difference between them in real time. When the moisture content of the silkworm excrement is still high and evaporation is intense, the temperature above the material layer rises slowly, and the temperature difference between the air inlet and the material layer will accelerate. Once the rate of temperature difference increase exceeds the first preset threshold, it indicates that the material is in a high-humidity, high-viscosity stage. High-frequency vibration can easily break up soft particles, producing fine powder and clogging the mesh, thus increasing air resistance. At this time, the module automatically adjusts the vibration frequency to 15Hz to 20Hz while keeping the amplitude unchanged. This relatively gentle vibration maintains the separation between particles, reduces the generation of fine powder, and avoids clogging the mesh, which would obstruct the flow of hot air. As drying progresses, the heat absorption from evaporation decreases, and the temperature above the material layer rapidly approaches the inlet air temperature. Once the rate of temperature difference decrease exceeds the second preset threshold, it indicates that the material is approaching dryness and has good air permeability. The module then increases the vibration frequency to 25Hz to 30Hz, while maintaining the amplitude. Higher frequency vibration enhances the uniform agitation of particles, accelerates the escape of residual moisture, prevents localized overheating, and improves the uniformity of moisture content in the entire batch of dried product. When the rate of temperature difference change is between the two thresholds, it indicates that the drying process is stable, and the vibration frequency remains unchanged, ensuring that the vibration intensity always matches the real-time state of the material.

[0019] Preferably, the temperature controller is further equipped with a pulse heating interference suppression module, which is triggered at the same time as the pulse heating self-cleaning module is started, and continues for 5 to 10 seconds after the pulse heating ends; During the duration of the pulse heating interference suppression module, the temperature controller pauses reading the signal from the temperature sensor above the silkworm excrement layer, stops the linkage control based on the dual temperature sensors, and maintains the current heating power of the hot air generator unchanged, retaining only the signal from the total air inlet temperature sensor for over-temperature protection; at the same time, the temperature controller disables the real-time temperature difference adjustment function of the vibration adaptive adjustment module, keeps the vibration frequency unchanged, and prohibits the operation of switching the phase angle difference between the two vibration motors from 0° to 180°. If the airflow settling self-cleaning program is triggered during the duration of the pulse heating interference suppression module, the aforementioned power maintenance state and shielding state will be immediately terminated, and the temperature controller will then execute the cooling command and comply with the rules of the airflow settling self-cleaning program regarding pausing and resuming moisture content sensor acquisition; after the current airflow settling self-cleaning program has completely ended, if there is still a remaining duration of the interrupted pulse heating interference suppression module, the temperature controller will immediately restart the pulse heating interference suppression module to complete the remaining duration; If the timing trigger unit of the pulse heating self-cleaning module reaches the preset trigger time during the execution of the airflow settling self-cleaning program, the temperature controller will not trigger the pulse heating self-cleaning for the time being. After the current airflow settling self-cleaning program is completely finished and the fan speed is restored to the rated value, the pulse heating self-cleaning will be executed immediately. The execution method of the pulse heating self-cleaning, the triggering of the matching pulse heating interference suppression module, the pause and resumption of the moisture content sensor detection signal acquisition, and the probe natural cooling conditions are all the same as those of the pulse heating self-cleaning triggered by the timing trigger unit. The acquisition of the moisture content sensor signal returns to normal after the duration of the pulse heating interference suppression module ends and the probe has naturally cooled to the temperature inside the drying chamber. After the duration of the pulse heating interference suppression module ends and the probe has naturally cooled to the temperature inside the drying chamber, if there is no conflict with the airflow settling self-cleaning program, the temperature controller resumes reading the signal from the temperature sensor above the silkworm excrement layer, resumes the linkage control based on the dual-channel temperature sensor, and removes the shielding of the real-time temperature difference adjustment function of the vibration adaptive adjustment module.

[0020] The pulse heating interference suppression module of the present invention is used to temporarily freeze the relevant control circuit during the short period of probe pulse heating self-cleaning and subsequent temperature field recovery, so as to avoid temperature detection distortion, temperature control circuit misadjustment and vibration adjustment logic disorder caused by local high temperature diffusion of the probe. It is a supporting guarantee logic for the pulse heating self-cleaning function.

[0021] Preferably, the vibration adaptive adjustment module is also equipped with a space frame self-cleaning mode, which is automatically triggered by the temperature controller at preset self-cleaning time intervals. The space frame self-cleaning mode is only allowed to be started when the airflow settling self-cleaning program is not executed, the real-time temperature difference adjustment function of the vibration adaptive adjustment module is not disabled, and the pulse heating interference suppression module is not in an active state. If the preset self-cleaning time interval is reached and the space frame self-cleaning mode is not started due to any of the above conditions not being met, it will be executed once immediately after all conditions are met. After the self-cleaning mode of the space frame is activated, the following operations are performed: The vibration adaptive adjustment module switches the phase angle difference between the two vibration motors from 0° to 180° through the frequency converter, causing the thin-layer breathable load-bearing space frame to generate horizontal reciprocating rubbing vibration for 5 to 10 seconds, and then restores the phase angle difference to 0°; During the operation of the self-cleaning mode of the space frame, the real-time temperature difference adjustment function of the vibration adaptive adjustment module is temporarily disabled, the vibration frequency remains unchanged at the current value, and the amplitude remains between 0.5mm and 2.0mm; If the airflow settling self-cleaning procedure is triggered during the operation of the space frame self-cleaning mode, the vibration adaptive adjustment module will immediately stop the space frame self-cleaning mode, restore the phase angle difference to 0°, and after the airflow settling self-cleaning procedure ends, if the pulse heating interference suppression module is not in an active state at this time, the remaining duration of the space frame self-cleaning mode will be immediately re-executed; if the pulse heating interference suppression module is in an active state, the mode will be re-executed immediately after the module ends. If the pulse heating self-cleaning module is triggered during the operation of the space frame self-cleaning mode, the vibration adaptive adjustment module will immediately stop the space frame self-cleaning mode, restore the phase angle difference to 0°, and allow the pulse heating self-cleaning module to perform normally; after the pulse heating self-cleaning and its interference suppression modules have been fully executed, the remaining duration of the space frame self-cleaning mode will be immediately re-executed.

[0022] In the present invention, the built-in self-cleaning mode for the mesh frame in the vibration adaptive adjustment module is automatically scheduled by the temperature controller at preset time intervals. This mode is only allowed to start when the airflow sedimentation self-cleaning procedure is not being executed, the real-time temperature difference adjustment function is not shielded, and the pulse heating interference suppression module is not in an active state; if any condition is not met when the timing expires, the execution will be postponed until all conditions are satisfied and then performed immediately once. After startup, the frequency converter switches the phase angle difference between the two vibration motors from 0° to 180°, so that the originally co-directional and synchronized vibration is transformed into horizontal reciprocating rubbing, driving the entire thin-layer breathable bearing mesh frame group to generate push-pull dislocation, and the phase angle difference is restored to 0° after lasting for 5 to 10 seconds. This movement mode helps to shake off residual materials and dust adhered to the surface of the mesh wires and embedded in the mesh holes, restoring the air permeability of the mesh frame. During the self-cleaning duration, the real-time temperature difference adjustment function is temporarily shielded, the vibration frequency remains at the current value, and the amplitude is maintained at 0.5mm to 2.0mm. If the airflow sedimentation self-cleaning procedure is triggered during operation, the mesh frame self-cleaning is immediately aborted and the phase angle difference is restored to 0°; after the airflow sedimentation procedure ends, if the pulse heating interference suppression module is not in an active state, the remaining duration is immediately continued; if the module is in an active state, the execution is continued immediately after it ends. If the pulse heating self-cleaning module is triggered, the mesh frame self-cleaning is also immediately aborted and the phase angle difference is restored, allowing the pulse heating self-cleaning and its interference suppression module to execute completely, and the remaining duration of the mesh frame self-cleaning is continued immediately after the entire process is completed.

[0023] The present invention at least includes the following beneficial effects: This drying system applies continuous micro-amplitude vibration to the multi-layer thin-layer breathable bearing mesh frames, so that the wet and sticky silkworm excrement remains loose and permeable during the drying process, and hot air can uniformly flow through each material layer, effectively overcoming the defects of uneven drying caused by material caking and frequent manual turning. The graded supplementary air path system adopts differentiated hot air supply in a proportion of more at the bottom and less at the top, which is beneficial to reducing the difference in the drying progress of materials on the upper and lower layers. The exhaust air first passes through a gas-gas plate heat exchanger to recover waste heat for preheating newly incoming cold air, and then is discharged after being purified by the odor composite adsorption module, which not only reduces the system heat consumption, but also controls the odor impact on the workplace and the surrounding environment. A probe-type moisture content sensor is used to monitor the moisture content of the uppermost layer of material, and dual temperature sensors are combined to realize the linkage control of hot air output; a pulse heating self-cleaning module and an airflow sedimentation self-cleaning procedure are provided to regularly clean the probe of the moisture content sensor and the thin-layer breathable bearing mesh frame respectively, and the mutual exclusion and interruption recovery rules between the pulse heating interference suppression module and each procedure ensure that the cleaning process does not affect the stability and continuity of drying control.

[0024] Other advantages, objectives and features of the present invention will be partially reflected in the following description, and partially will be understood by those skilled in the art through research and practice of the present invention. Brief Description of the Drawings

[0025] Figure 1 This is a three-dimensional schematic diagram of the drying chamber of the low-odor, high-efficiency silkworm excrement drying system of the present invention; Figure 2 This is a schematic diagram of the cross-section of the drying chamber of the low-odor, high-efficiency silkworm excrement drying system of the present invention; The reference numerals in the attached figures are explained as follows: 1. Drying chamber; 2. Exhaust duct; 3. Upper air inlet; 4. Central air inlet; 5. Lower air inlet; 6. Space frame; 7. Elastic support components; 8 fresh air ducts; 9-gas plate heat exchanger; 10 Odor Composite Adsorption Modules; 11. Hot air generating device. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0027] It should be noted that terms such as “having,” “comprising,” and “including” used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0028] like Figure 1-2 As shown, the present invention provides a low-odor, high-efficiency drying system for silkworm excrement, comprising: The drying chamber 1 has insulation layers on its side walls and top. The multi-layer thin-layer breathable load-bearing mesh frame 6 is fixed to each other by rigid connectors to form a whole. The whole is connected to the inner wall of the drying chamber by elastic support 7. Silkworm excrement is manually laid on the thin-layer breathable load-bearing mesh frame. The vibration anti-caking component includes two vibration motors, which are symmetrically installed on both sides of the bottom of the lowest thin-layer breathable load-bearing mesh frame. The graded air supply directional airflow system includes a three-tiered air inlet, a top directional exhaust outlet, a one-way valve, an air-to-air plate heat exchanger, and a hot air generator. The three-tiered air inlets are distributed sequentially along the lower, middle, and upper parts of the drying chamber. The lower air inlet is located below the lowest thin-layer permeable support mesh frame, the middle air inlet is located below the middle layer of the multi-layer thin-layer permeable support mesh frame, and the upper air inlet is located below the uppermost thin-layer permeable support mesh frame. The three-tiered air inlets correspond to the fresh air supply in the lower, middle, and upper parts. The air ratio is 3:2:1, which is achieved by an air volume distribution valve set at the total air inlet of the three-level air inlet. The top directional exhaust port is set at the top of the drying chamber. The exhaust air from the top directional exhaust port enters the air-to-air plate heat exchanger for heat release through a one-way valve. The fresh air is preheated by the air-to-air plate heat exchanger 9 and then heated by the hot air generator 11 and sent to the total air inlet of the three-level air inlet. The outlet of the hot air generator is connected to the total air inlet through a pipe. The total air inlet is connected to the lower air inlet 5, the middle air inlet 4, and the upper air inlet 3 through pipes respectively. Odor adsorption module 10 is connected to the exhaust channel outlet of air-to-air plate heat exchanger 9 and uses a composite filter of activated carbon and mulberry leaf fiber. The intelligent temperature control system with dual linkage between moisture content and temperature includes a moisture content sensor, dual temperature sensors, and a temperature controller. The temperature controller is electrically connected to the moisture content sensor, the dual temperature sensors, and the hot air generator.

[0029] One specific implementation method of this low-odor, high-efficiency silkworm excrement drying system is as follows: The drying chamber 1 can be constructed as a cuboid 1.5 meters long, 1 meter wide, and 1.8 meters high, with an 80mm thick rock wool board as insulation on the outer wall. Inside the chamber, 10 to 12 layers of thin, breathable, load-bearing mesh frames 6 are installed, with a layer spacing of 10-12cm. Each layer of mesh frames is welded together into a rigid whole using angle steel connectors, and this whole is elastically supported on the inner wall of the chamber by four rubber shock absorbers. The mesh frames 6 themselves can be made of stainless steel woven mesh with a 3mm aperture, facilitating the manual placement of wet silkworm excrement. Two small vibrating motors are symmetrically installed on both sides of the bottom of the lowest mesh frame, with an excitation frequency adjustable between 15Hz and 30Hz and an amplitude set between 0.5mm and 2.0mm. The graded supplementary directional airflow system consists of three layers of graded air inlets distributed along the height of the chamber, a top directional exhaust outlet, one-way valves, an air-to-air plate heat exchanger, and a hot air generator. Perforated air distribution plates can be installed on the inner side of the air inlets of each layer, so that the hot air entering the silo can initially diffuse in the space below the corresponding grid frame before penetrating the material layer upward.

[0030] The lower air inlet is located below the bottommost mesh frame, the middle air inlet is located below the sixth mesh frame, and the upper air inlet is located below the topmost mesh frame. These three air inlets are staggered on the left and right sides of the chamber to ensure even airflow distribution. A manual airflow distribution valve is installed at the main air inlet, allowing the total airflow to be distributed to the lower air inlet 5, middle air inlet 4, and upper air inlet 3 in a 3:2:1 ratio. The top directional exhaust outlet is connected to the hot-side inlet of the air-to-air plate heat exchanger 9 via exhaust duct 2 and a one-way valve. Fresh outdoor air is introduced to the cold side of the heat exchanger via fresh air duct 8. The hot air generating device 11 includes a low-pressure centrifugal fan and a set of electric heating tubes. Preheated fresh air is heated here before being sent to the main air inlet. The exhaust outlet of the heat exchanger is connected to an odor composite adsorption module 10, which is filled with a replaceable activated carbon and mulberry leaf fiber composite filter. The dual-linkage intelligent temperature control system for moisture content and temperature includes a probe-type moisture content sensor, two PT100 platinum resistance thermometers, and a temperature controller. The moisture content sensor is fixed to the uppermost mesh frame via a bracket and inserted into the silkworm excrement layer. One temperature sensor is installed inside the main air inlet duct, and the other is installed 15cm above the uppermost silkworm excrement layer in the storage space. The temperature controller is electrically connected to the moisture content sensor, the two temperature sensors, the vibration motor, and the fan and heater of the hot air generator. Both the windward and leeward sides of the filter frame are lined with stainless steel wire mesh with a mesh size of at least 40. A non-woven fabric pre-filter layer is also installed between the windward mesh and the activated carbon-mulberry leaf fiber filling layer to intercept fine dust carried by the exhaust air and prevent mulberry leaf fiber debris from being carried out by the airflow. This is a composite filter screen made of activated carbon and mulberry leaf fiber. The activated carbon can be coal-based columnar activated carbon with an iodine value of not less than 800 mg / g and a particle size between 2 mm and 4 mm. The mulberry leaf fiber can be obtained from dried mulberry leaves, separated into fiber bundles through rubbing or mechanical combing, and then cut into short fibers of 1 mm to 3 mm in length; alternatively, dried mulberry leaves can be coarsely crushed and sieved to obtain 1 mm to 3 mm flaky fragments. The dry weight mixing ratio of activated carbon and mulberry leaf fiber can be selected between 3:1 and 5:1. After thorough mixing, the mixture is placed into a replaceable filter frame, with a filling thickness of 5 cm to 10 cm and a filling density of approximately 0.4 g / cm³ to 0.6 g / cm³. Mulberry leaf fiber is rich in cellulose and polyphenols, which can assist in the adsorption of ammonia and indole polar odor molecules released from silkworm excrement, complementing the broad-spectrum adsorption of activated carbon. Before filling, mulberry leaf fibers can be treated by high-temperature steaming or soaking in dilute alkaline solution to remove some soluble nutrients and delay mold growth. In actual use, depending on the batch of silkworm excrement being processed and the exhaust humidity, it is recommended to replace the composite filter every 5 to 10 drying batches.

[0031] During operation, fresh silkworm excrement is manually and evenly spread on each layer of the mesh frame, with a thickness of approximately 2 to 3 cm. After the vibration motor is started, the entire mesh frame vibrates continuously with slight amplitude under the support of rubber shock absorbers, preventing the silkworm excrement particles from forming stable adhesion and keeping the material layer loose and breathable. A hot air generator heats clean air to 60°C to 90°C and sends it proportionally into the three-tiered air inlets through an airflow distribution valve. The hot air penetrates vertically upwards from below the mesh frame, carrying away moisture and forming a humid and hot airflow that gathers upwards at the top of the silo. The top directional exhaust vents press this humid and hot air through a one-way valve into an air-to-air plate heat exchanger, where it exchanges heat with the cool fresh air. The fresh air is preheated to about 40°C before entering the heating section, while the humid and hot exhaust air, after cooling, flows through a composite filter of activated carbon and mulberry leaf fiber, adsorbing odor components before being discharged into the atmosphere. During the drying process, the temperature controller reads signals from the moisture content sensor and two temperature sensors in real time. Based on the changes in the moisture content of the top layer of silkworm excrement and the temperature difference between the air inlet and the material layer, it adjusts the heating power and fan speed accordingly. When the moisture content of the top layer of silkworm excrement drops to the set threshold of 13%, the controller cuts off the heater power, and the fan continues to run for several minutes before stopping, completing one drying batch.

[0032] Implementing the system described in this solution eliminates the need for manual turning after material is laid out. The permeability of the material layer is maintained by slight vibrations of the mesh frame, preventing hot air short-circuiting and uneven drying caused by silkworm excrement clumping. The three-layered, progressively decreasing airflow supply and staggered air intake structure can match the drying requirements of materials at different heights, improving the difference in moisture content between upper and lower layers. Exhaust air undergoes waste heat recovery and composite adsorption treatment, reducing heating energy consumption and odor emissions in the working environment. Direct moisture content detection using probes, combined with comprehensive control based on dual-point temperature differences, allows for more accurate determination of the drying endpoint, reducing the likelihood of over-drying or under-drying, and resulting in more consistent moisture content in the dried silkworm excrement.

[0033] Based on the above implementation method, this specific implementation method makes more detailed settings for the vibration and detection control links. The vibration frequency of the two vibration motors can be selected within the range of 15Hz to 30Hz, and the amplitude can be set between 0.5mm and 2.0mm. Driven by a frequency converter, the entire mesh frame assembly makes continuous small-amplitude high-frequency vibration, making it difficult for the wet and sticky silkworm excrement particles to form stable bridging and adhesion, keeping the material layer in a loose state, and maintaining the gaps for hot air flow. The moisture content sensor adopts a probe-type structure, with a probe length of about 10cm. It is fixed to the upper surface of the uppermost thin-layer breathable support mesh frame by a stainless steel bracket. The probe is inserted vertically into the silkworm excrement material layer to a depth of about 1.5cm to 2.5cm to sense the moisture content of the uppermost material in real time. The uppermost layer is chosen as the detection point because it is at the end of the air path and the drying process is the slowest. Using its moisture content as the basis for judging the drying endpoint can reliably reflect whether the entire batch of material has reached the target dryness, avoiding insufficient drying caused by using the dried material in the lower layers as the standard.

[0034] The temperature detection section uses two independent PT100 platinum resistance temperature sensors. The first sensor is installed inside the main air inlet duct to measure the temperature of the mixed hot air entering the three-stage air inlet. The second sensor is fixed inside the drying chamber by a mounting bracket, with its probe located 15cm above the top layer of silkworm excrement. This position is on the path of the rising airflow and can sensitively reflect the temperature of the airflow after penetrating the entire material layer. The temperature controller receives these two temperature signals and calculates the temperature difference between them in real time. In the early stage of drying, the silkworm excrement has a high moisture content, resulting in strong evaporation and heat absorption. The airflow temperature above the material layer rises slowly, and the temperature difference between the inlet air temperature and the temperature above the material layer is large. As drying progresses, the moisture content of the material gradually decreases, the evaporation and heat absorption decrease, and the temperature above the material layer gradually approaches the inlet air temperature, thus narrowing the temperature difference. Based on this trend of temperature difference and the reading of the moisture content sensor at the top layer, the controller adjusts the heating power and fan speed of the hot air generator to match the heat supply with the real-time dehumidification needs of the material, rather than simply maintaining a constant air temperature and volume.

[0035] Compared to traditional methods that rely solely on timed or single-point temperature control, this linkage method, which combines probe-based direct moisture content detection with a comprehensive judgment of dual-channel temperature difference trends, can respond more promptly to changes in the material's drying state. When the temperature difference is still large and the moisture content is high, the system maintains a high heat output; as the temperature difference gradually narrows and the moisture content approaches the set threshold of 13%, the controller automatically reduces the heating power, avoiding overheating in the later stages of drying due to low material moisture content. Determining the drying endpoint no longer depends on operator experience; once the uppermost probe reading reaches the set threshold, the system stops heating, thereby reducing the risk of mold growth during storage due to insufficient drying and energy waste caused by over-drying.

[0036] Based on the above embodiments, this specific embodiment further includes a pulse heating self-cleaning module to keep the surface of the moisture content sensor probe clean.

[0037] This pulse heating self-cleaning module consists of a miniature heating wire embedded inside the probe and a timing trigger unit integrated into the temperature controller. The probe itself can be a commercially available stainless steel probe-type moisture sensor. A nickel-chromium alloy heating wire with a diameter of approximately 0.3 mm is inserted into its internal hollow cavity. An insulating and thermally conductive layer, formed by the curing of thermally conductive insulating adhesive, is filled between the heating wire and the inner wall of the probe. Typically, alumina filled with epoxy resin, which has a high thermal conductivity, is used. This insulating and thermally conductive layer efficiently transfers heat from the heating wire to the outer surface of the probe and also provides electrical isolation between the heating wire and the metal probe body. The timing trigger unit can be implemented in the microprocessor of the temperature controller via a software timer, or a separate time relay module can be used.

[0038] During operation, the timed trigger unit automatically outputs a pulse current every 60 minutes, with each pulse lasting 0.3 seconds. At this instant, the micro-heating wire rapidly heats up, and the heat is conducted through the insulating thermal conductive layer to the probe's outer surface, causing its temperature to rise instantly to 80°C. The silkworm excrement and mucus adhering to the probe surface rapidly lose water upon being heated, and the organic matter within it develops micro-cracks due to thermal stress, changing from a sticky and tough state to a brittle one. This temperature is below the charring temperature of the organic matter in the silkworm excrement, preventing the production of a burnt odor. After the pulse ends, the probe cools naturally under the airflow within the drying chamber and undergoes slight shrinkage. Simultaneously, the continuous micro-amplitude mechanical vibration from the mesh frame vibration motor is transmitted to the probe, causing the dried and brittle adhering layer to peel off the probe surface, restoring direct contact between the probe and the silkworm excrement. During the pulse current output and subsequent cooling phases, the temperature controller automatically pauses the moisture content sensor's detection signal acquisition. Normal measurement resumes once the probe temperature drops to near the ambient temperature within the chamber, thus avoiding distortion caused by the probe's self-heating leading to excessively high moisture content readings.

[0039] Compared to relying solely on mesh frame vibration or manual wiping to maintain probe cleanliness, this timed pulse self-heating method requires no manual intervention and involves only a brief cleaning action, having virtually no impact on the continuity of the drying process. The temporary shielding of moisture content signal acquisition during cleaning ensures that the measurement data entering the temperature controller always reflects the true moisture content of the material, preventing erroneous signals due to probe surface crusting or self-heating, thus maintaining the reliability of the drying endpoint determination. It should be noted that the target temperature of 70℃ to 90℃ mentioned above is the peak value achievable during the early stages of drying when the chamber temperature is relatively low. During the later stages of drying when the chamber temperature is higher, the temperature rise from pulse heating will be reduced or cease, but combined with the continuous mechanical stripping action transmitted by the vibrating motor, it can still effectively remove most of the adhering substances from the probe surface.

[0040] Based on the above implementation method, this specific implementation method is equipped with an airflow settling self-cleaning program inside the temperature controller, which is used to remove fine dust and debris suspended in the chamber during the drying process.

[0041] The airflow settling self-cleaning program is automatically triggered by the microprocessor in the temperature controller at preset time intervals, which can be set to 20 minutes. Each time it is triggered, the temperature controller sends a speed-reducing command to the low-pressure centrifugal fan in the hot air generator, causing the fan speed to gradually decrease from the rated speed to 15% of the rated speed within 8 seconds. This low speed is maintained for 10 to 20 seconds, and then gradually returns to the rated speed within 5 seconds. This sudden decrease in airflow causes the fine silkworm excrement dust and debris, which were originally suspended above the material layer and between the mesh frame openings by the rising airflow, to lose their supporting force and settle back to the surface of the material layer or below the mesh frame under their own gravity. This reduces the tendency for these particles to be repeatedly stirred up in the circulating airflow within the silo and adhere to the duct walls and the wire diameter of the mesh frame.

[0042] Throughout the airflow settling self-cleaning process, the temperature controller simultaneously performs a series of temporary control freeze operations. The moisture content sensor's signal acquisition is paused to prevent drift in the measured values ​​caused by short-term temperature fluctuations within the chamber, which are transmitted to the probe via the material. Simultaneously, the temperature controller suspends the temperature difference-based adjustment function based on the dual-channel temperature sensors, no longer adjusting the heating output based on the temperature difference between the air inlet and the material layer. The heating power is then independently controlled by the airflow settling self-cleaning program, which reduces the heater power to 15% of its rated power to match the significantly reduced airflow. Only the signal from the temperature sensor at the main air inlet is retained for over-temperature protection, preventing excessively high local temperatures near the heating element due to a sudden drop in airflow. After the deceleration period ends, the temperature controller sends an acceleration command to the fan, restoring it to its rated speed. Simultaneously, the heater's original power is restored, followed by the resumption of normal moisture content sensor acquisition and dual-channel temperature sensor-based linkage control, returning the system to normal drying and adjustment mode.

[0043] Compared to the conventional approach of relying solely on mesh frame vibration to prevent dust accumulation, this timed, significant airflow reduction method actively separates already stirred-up fine dust from the airflow, reducing repeated circulation and adhesion of dust within the mesh and air ducts, and slowing down the degradation of the mesh frame's permeability. Simultaneously, the adjustment of heating power and temporary shielding of some sensor signals during the deceleration period prevent short-term airflow turbulence from interfering with drying control and measurement accuracy, ensuring that the cleaning action itself does not adversely affect the material drying process or endpoint determination.

[0044] Based on the above implementation method, this specific implementation method further limits the control logic of the hot air generating device in the airflow settling self-cleaning process, so that the fan speed reduction and heater power reduction are executed in coordination, and preheating is completed before the air supply is restored.

[0045] The hot air generating unit includes a low-pressure centrifugal fan and a set of electric heating elements. The fan speed can be adjusted via a frequency converter, and the power of the electric heating elements can be continuously or steppedly adjusted via a solid-state relay or thyristor power controller. The temperature controller is connected to both the frequency converter's control terminal and the power controller's input terminal, enabling it to independently send speed commands to the fan and power commands to the heaters. When the airflow settling self-cleaning program is triggered, the temperature controller no longer simply reduces the fan speed; instead, it simultaneously outputs a speed reduction command and a heat reduction command. The speed reduction command gradually reduces the fan speed to 15% of its rated speed within 8 seconds, while the heat reduction command synchronously reduces the heater power to 15% of its rated power within the same timeframe, or, depending on the actual situation, completely shuts down the heater. The significant reduction in fan airflow is matched by a corresponding decrease in heating power, preventing a sharp rise in the air temperature around the heating elements due to a sudden decrease in airflow while maintaining high heating power, thus preventing localized overheating and damage to equipment and materials.

[0046] As the deceleration phase of the airflow settling self-cleaning process is about to end, the temperature controller sends a preheating command to the heater before issuing an increase command to the fan. The preheating command is issued 3 seconds before the fan speed resumes normal operation. At this moment, the heater returns to its original power level before deceleration, and the heating element begins to heat up, transferring heat to the surrounding air that has not yet been rapidly blown away. After this 3-second preheating buffer, the surface temperature of the heating element has returned to its normal operating range, and the air in the heating chamber has been initially heated. At this point, the temperature controller sends an increase command to the fan, restoring it to its rated speed and delivering the preheated airflow into the air inlet duct and drying chamber. This preheating-then-increase sequence avoids a temporary drop in the supply air temperature caused by the sudden return of normal-temperature airflow to the cold heating element. This ensures a smooth transition in the drying temperature inside the chamber after the airflow settling self-cleaning process, without requiring a temperature ramp-up.

[0047] Compared to methods that only reduce airflow without reducing heat or that start and stop airflow and heat simultaneously without a preheating sequence, this control method, which combines airflow reduction and heat reduction and preheats before resuming airflow, eliminates the risk of overheating during the deceleration period and shortens the temperature recovery time after resuming airflow. This makes the entire airflow settling and self-cleaning process have less impact on the continuity of material drying.

[0048] Based on the above implementation method, this specific implementation method is equipped with a vibration adaptive adjustment module inside the temperature controller. This module can adjust the working frequency of the vibration motor in real time according to the changes in the drying state of the material.

[0049] The vibration adaptive adjustment module can be implemented through a PID control loop or programmable logic control function within the temperature controller. This module is connected to two vibration motors via a frequency converter, allowing independent setting of the vibration frequency while maintaining an initial phase angle difference of 0 degrees between the two motors. A commercially available low-power vector frequency converter can be used as the frequency converter. The dual temperature sensors continue to utilize the existing PT100 platinum resistance temperature sensor at the main air inlet and the PT100 platinum resistance temperature sensor installed 15cm above the top layer of silkworm excrement inside the drying chamber. During operation, the module continuously reads these two temperature signals, calculates the temperature difference between the main air inlet temperature and the temperature above the silkworm excrement layer in real time, and monitors the rate of change of this temperature difference over time.

[0050] During the normal drying stage when the airflow settling self-cleaning process is not executed, the vibration adaptive adjustment module adjusts the vibration frequency according to the temperature difference change rate and preset rules. When the silkworm excrement is in a high-humidity stage, moisture evaporation is rapid, and the temperature above the material layer rises slowly, causing the temperature difference between the air inlet and the material layer to widen rapidly. Once the rate of increase in temperature difference exceeds the preset threshold of 1.2℃ per minute, the module determines that the material is in a high-humidity and high-viscosity state. At this time, excessive vibration can easily break up the soft, wet silkworm excrement particles, producing fine powder that clogs the mesh and increases air resistance. The module then automatically lowers the vibration frequency to 18Hz, while keeping the amplitude unchanged from the original setting, maintaining the separation between particles with relatively gentle vibration, reducing the generation of fine powder, and keeping the mesh open. As the drying process progresses, the moisture content of the material gradually decreases, evaporation and heat absorption weaken, the temperature above the material layer accelerates towards the air inlet temperature, and the temperature difference begins to narrow rapidly. When the rate of decrease in temperature difference exceeds a preset threshold of 1.0℃ per minute, the module determines that the material is nearly dry, the inter-particle stickiness has largely disappeared, and the material layer has good air permeability. At this point, the vibration frequency is increased to 28Hz, while maintaining the amplitude unchanged. A higher vibration frequency can enhance the uniformity of particle agitation, accelerate the escape of residual moisture, and prevent localized overheating. When the rate of change in temperature difference is between these two thresholds, the module determines that the drying process is stable, and the vibration frequency remains unchanged at the current value.

[0051] Based on the above implementation, this specific implementation includes a pulse heating interference suppression module configured inside the temperature controller. This module is a supporting guarantee logic for the pulse heating self-cleaning function. It is used to temporarily freeze the relevant control loop during the short period of probe self-cleaning and subsequent temperature field recovery to avoid detection distortion and control disorder caused by the local high temperature diffusion of the probe.

[0052] The pulse heating interference suppression module is implemented by the microprocessor of the temperature controller through software flags and timers. When the timing trigger unit of the pulse heating self-cleaning module outputs a pulse current to start the pulse heating self-cleaning, the interference suppression module is triggered synchronously, and the duration is set to 8 seconds after the pulse heating ends. During this period, the temperature controller performs a series of temporary freezing operations. First, the temperature controller pauses reading the signal from the second temperature sensor installed 15cm above the silkworm excrement layer, stops the temperature difference linkage control based on the dual temperature sensors, and maintains the current heating power of the hot air generator unchanged, retaining only the signal from the temperature sensor at the main air inlet for over-temperature protection. Second, the temperature controller disables the real-time temperature difference adjustment function of the vibration adaptive adjustment module, keeping the vibration frequency unchanged, and prohibits the operation of switching the phase angle difference between the two vibration motors from 0 degrees to 180 degrees. The core purpose of these freezing measures is to prevent the small local temperature rise generated by the probe pulse heating from being captured by the upper temperature sensor and amplified by the temperature difference linkage loop into a misadjustment of the heating power, and also to prevent the linkage changes of vibration parameters from interfering with the peeling and sedimentation of the probe surface adhesion layer.

[0053] If the 20-minute timer of the airflow settling self-cleaning procedure reaches its trigger point exactly within the 8-second duration of the pulse heating interference suppression module, the aforementioned power maintenance and shielding states will immediately cease. The temperature controller will then execute the cooling commands specified in the airflow settling self-cleaning procedure and comply with the procedure's rules regarding pausing and resuming moisture content sensor data acquisition. After the current airflow settling self-cleaning procedure has completely ended, if there is still a remaining 8-second duration of the interrupted pulse heating interference suppression module, the temperature controller will immediately restart the pulse heating interference suppression module to complete the remaining duration, ensuring that the temperature field recovery and signal shielding after pulse heating are fully executed.

[0054] Conversely, if the timing trigger unit of the pulse heating self-cleaning module reaches its preset 60-minute trigger time during the airflow settling self-cleaning program, the temperature controller will not trigger this pulse heating self-cleaning. After the current airflow settling self-cleaning program has completely ended and the fan speed has returned to its rated value, the temperature controller will immediately execute another pulse heating self-cleaning. The execution method of this pulse heating self-cleaning, the triggering of the matching pulse heating interference suppression module, the pause and resumption rules for the moisture content sensor detection signal acquisition, and the probe natural cooling conditions are all exactly the same as those of the pulse heating self-cleaning normally triggered by the timing trigger unit.

[0055] The acquisition of the moisture content sensor's detection signal can only resume normal operation after two conditions are met simultaneously: the duration of the pulse heating interference suppression module has ended and the probe has naturally cooled to the temperature inside the drying chamber. Once the pulse heating interference suppression module's duration has ended and the probe has naturally cooled, if there is no ongoing airflow settling self-cleaning program interfering with this, the temperature controller resumes reading the signal from the temperature sensor above the silkworm excrement layer, resumes the linkage control based on the dual-channel temperature sensors, and removes the shielding of the vibration adaptive adjustment module's real-time temperature difference adjustment function. The system then fully returns to normal drying and adjustment status.

[0056] Whether the probe has cooled to the chamber temperature can be determined by comparing the deviation between the last reading of the moisture content sensor before the pause and the first reading after the restart; if the deviation exceeds a preset range, the waiting time is extended. Alternatively, a miniature thermocouple can be integrated inside the probe, and the temperature controller reads the thermocouple signal, determining that cooling is complete when the difference between the probe temperature and the chamber temperature sensor reading is less than a preset threshold.

[0057] Based on the above implementation method, this specific implementation method is equipped with a self-cleaning mode for the mesh frame inside the vibration adaptive adjustment module, which is used to periodically remove residual materials and dust embedded in the surface of the thin-layer breathable bearing mesh frame wires and mesh holes, and restore the breathability of the mesh frame.

[0058] The space frame self-cleaning mode is automatically triggered every 120 minutes by the temperature controller. This mode has strict activation conditions and is only allowed to execute when three conditions are met simultaneously: the airflow settling self-cleaning program is not running, the real-time temperature difference adjustment function of the vibration adaptive adjustment module is not disabled, and the pulse heating interference suppression module is not active. If any of the above conditions are not met when the 120-minute timer expires, the space frame self-cleaning mode will not be forcibly activated but will enter a waiting state, executing immediately once all conditions are met.

[0059] After the grid self-cleaning mode is activated, the vibration adaptive adjustment module switches the phase angle difference between the two vibration motors from 0 degrees to 180 degrees through the frequency conversion controller. The two vibration motors originally operate in the same direction and synchronously. After switching to the opposite phase, the exciting forces they generate are in opposite directions, so that the movement form of the entire thin-layer breathable bearing grid assembly changes from vertical up-and-down vibration to horizontal reciprocating rubbing vibration. This rubbing mode can exert a shearing effect on the surface of the grid wires, rubbing off the residual materials adhered to the grid wires and the dust embedded in the grid holes. The rubbing vibration lasts for 8 seconds, then the frequency conversion controller restores the phase angle difference to 0 degrees, and the grid assembly resumes normal vertical vibration. During the operation of the grid self-cleaning mode, the real-time temperature difference adjustment function of the vibration adaptive adjustment module is temporarily shielded, the vibration frequency remains at the current value, and the amplitude is kept at the original set value, so as to avoid the linkage change of frequency and amplitude caused by the movement form switching. The reciprocating rubbing vibration refers to making the thin-layer breathable bearing grid generate repeated torsional oscillation around the horizontal axis, driving the surface of the grid wires to produce a shearing and rubbing effect on the attached residual materials.

[0060] If the airflow sedimentation self-cleaning program is triggered during the 8-second operation of the grid self-cleaning mode, the vibration adaptive adjustment module immediately suspends the grid self-cleaning mode and restores the phase angle difference to 0 degrees. After the airflow sedimentation self-cleaning program is completely finished, if the pulse heating interference suppression module is not in an active state at this time, the remaining duration of the grid self-cleaning mode will be re-executed immediately. If the pulse heating interference suppression module is in an active state after the airflow sedimentation self-cleaning program ends, the remaining duration will be re-executed immediately after the module finishes running.

[0061] If the pulse heating self-cleaning module is triggered during the 8-second operation of the grid self-cleaning mode, the vibration adaptive adjustment module also immediately suspends the grid self-cleaning mode, restores the phase angle difference to 0 degrees, and allows the pulse heating self-cleaning module to execute normally. After the pulse heating self-cleaning and its supporting interference suppression module are all executed, the remaining duration of the grid self-cleaning mode will be re-executed immediately.

[0062] Although the embodiments of the present invention have been disclosed above, the present invention is not limited to the applications set forth in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily realized.

Claims

1. A low-odor, high-efficiency drying system for silkworm excrement, characterized in that, include: The drying chamber has insulation layers on its side walls and top. The multi-layer thin-layer breathable load-bearing mesh frame is fixed to each other by rigid connectors to form a whole. The whole is connected to the inner wall of the drying chamber by elastic support. Silkworm excrement is manually laid on the thin-layer breathable load-bearing mesh frame. The vibration anti-caking component includes two vibration motors, which are symmetrically installed on both sides of the bottom of the lowest thin-layer breathable load-bearing mesh frame. The graded air supply directional airflow system includes a three-layer graded air inlet, a top directional exhaust outlet, a one-way valve, an air-to-air plate heat exchanger, and a hot air generator. The three-layer graded air inlets are distributed sequentially along the lower, middle, and upper parts of the drying chamber. The lower air inlet is located below the lowest thin-layer permeable support frame, the middle air inlet is located below the middle layer of the multi-layer thin-layer permeable support frame, and the upper air inlet is located below the uppermost thin-layer permeable support frame. The fresh air supply ratio of the three-layer graded air inlets to the lower, middle, and upper parts is 3:2:

1. This ratio is achieved by the airflow distribution valve located at the total air inlet end of the three-layer graded air inlets. The top directional exhaust outlet is located at the top of the drying chamber. The exhaust air from the top directional exhaust outlet enters the air-to-air plate heat exchanger for heat release through the one-way valve. The fresh air is preheated by the air-to-air plate heat exchanger and then heated by the hot air generator before being sent to the total air inlet end of the three-layer graded air inlets. The odor adsorption module is connected to the exhaust channel outlet of the gas-gas plate heat exchanger and uses a composite filter of activated carbon and mulberry leaf fiber. The moisture content and temperature dual-linkage intelligent temperature control system includes a moisture content sensor, dual temperature sensors, and a temperature controller. The temperature controller is electrically connected to the moisture content sensor, dual temperature sensors, and hot air generator, respectively.

2. The low-odor, high-efficiency silkworm excrement drying system according to claim 1, characterized in that, The vibration frequency of the vibrating motor is 15Hz to 30Hz, and the amplitude is 0.5mm to 2.0mm. The moisture content sensor is a probe-type sensor, which is fixed to the upper surface of the uppermost thin-layer breathable support mesh frame by a bracket and inserted into the interior of the silkworm excrement layer. The state of the uppermost material is used as the basis for judging the drying endpoint. Dual temperature sensors are installed at the main air inlet of the three-layer graded air inlet and 10cm to 20cm above the uppermost silkworm excrement layer inside the drying chamber, respectively, for linkage control of hot air output.

3. The low-odor, high-efficiency silkworm excrement drying system according to claim 2, characterized in that, The dual-linkage intelligent temperature control system for moisture content and temperature also includes a pulse heating self-cleaning module. This module comprises a miniature heating wire embedded inside the moisture content sensor probe and a timing trigger unit located in the temperature controller. The miniature heating wire contacts the probe's outer surface through an insulating thermally conductive layer. The timing trigger unit outputs a pulse current to the miniature heating wire at preset time intervals, lasting 0.1 to 0.5 seconds, causing the probe surface temperature to instantly rise to 70°C to 90°C. Subsequently, the adhering layer peels off under the combined action of natural cooling and vibration generated by the vibration motor. When the timing trigger unit outputs the pulse current, the temperature controller automatically pauses the acquisition of the moisture content sensor's detection signal. After the pulse ends and the probe naturally cools to the temperature inside the drying chamber, the temperature controller resumes normal acquisition.

4. The low-odor, high-efficiency silkworm excrement drying system according to claim 3, characterized in that, The temperature controller is also equipped with an airflow settling self-cleaning program. This program is triggered at preset time intervals. Each time it is triggered, the temperature controller outputs a speed reduction command to the hot air generator, reducing the fan speed to 10% to 20% of the rated speed within 5 to 10 seconds, and maintaining this low speed for 5 to 30 seconds. During the execution of the airflow settling self-cleaning program, the operating status of the vibration motor remains unchanged. During the speed reduction, the acquisition of the moisture content sensor's detection signal is suspended, the temperature controller suspends the linkage control based on the dual-channel temperature sensor, and the heating power switches to a power reduction protection mode, which is independently controlled by the airflow settling self-cleaning program. Only the signal from the main air inlet temperature sensor is retained for over-temperature protection. After the low speed maintenance ends, the temperature controller restores the rated speed of the hot air generator and the normal acquisition of the moisture content sensor, and resumes the linkage control based on the dual-channel temperature sensor. The preset time interval is 10 to 30 minutes.

5. The low-odor, high-efficiency silkworm excrement drying system according to claim 4, characterized in that, The hot air generating device includes a fan and a heater, and the temperature controller is also connected to the power control terminal of the heater. When the airflow settling self-cleaning program is triggered, the temperature controller simultaneously outputs a speed reduction command and a heat reduction command to the hot air generating device. The heat reduction command reduces the power of the heater to 10% to 20% of the rated power or shuts it off completely during the fan speed reduction period. And 2 to 5 seconds before the fan speed recovers, the temperature controller first outputs a preheating command to the heater to restore the heater power to the level before the speed reduction, and then outputs a speed increase command to the fan to restore the rated speed.

6. The low-odor, high-efficiency silkworm excrement drying system according to claim 5, characterized in that, The temperature controller is also equipped with a vibration adaptive adjustment module. This module connects to two vibration motors via a frequency converter and can adjust the vibration frequency and phase angle difference, with an initial phase angle difference of 0°. The module is electrically connected to both the dual-channel temperature sensors and the frequency converter control terminals of the vibration motors. The module calculates in real-time the temperature difference between the total inlet temperature and the temperature above the silkworm excrement layer from the total inlet temperature of the dual-channel temperature sensors. When the airflow settling self-cleaning procedure is not executed, it adjusts the vibration frequency of the vibration motors according to the rate of change of the temperature difference, following these rules: When the rate of increase of the temperature difference exceeds the first preset threshold, the vibration adaptive adjustment module will reduce the vibration frequency to 15Hz to 20Hz while keeping the amplitude unchanged. When the rate of decrease of the temperature difference exceeds the second preset threshold, the vibration adaptive adjustment module will increase the vibration frequency to 25Hz to 30Hz while keeping the amplitude unchanged. When the rate of increase of the temperature difference does not exceed the first preset threshold and the rate of decrease does not exceed the second preset threshold, the vibration frequency remains at the current value. The first preset threshold is a threshold for the rate of increase of temperature difference, with a value range of 0.5℃ / min to 2.0℃ / min; the second preset threshold is a threshold for the rate of decrease of temperature difference, with a value range of 0.5℃ / min to 2.0℃ / min.

7. The low-odor, high-efficiency silkworm excrement drying system according to claim 6, characterized in that, The temperature controller is also equipped with a pulse heating interference suppression module, which is triggered when the pulse heating self-cleaning module is started and continues for 5 to 10 seconds after the pulse heating ends. During the duration of the pulse heating interference suppression module, the temperature controller pauses reading the signal from the temperature sensor above the silkworm excrement layer, stops the linkage control based on the dual temperature sensors, and maintains the current heating power of the hot air generator unchanged, retaining only the signal from the total air inlet temperature sensor for over-temperature protection; at the same time, the temperature controller disables the real-time temperature difference adjustment function of the vibration adaptive adjustment module, keeps the vibration frequency unchanged, and prohibits the operation of switching the phase angle difference between the two vibration motors from 0° to 180°. If the airflow settling self-cleaning program is triggered during the duration of the pulse heating interference suppression module, the aforementioned power maintenance state and shielding state will be immediately terminated, and the temperature controller will then execute the cooling command and comply with the rules of the airflow settling self-cleaning program regarding pausing and resuming moisture content sensor acquisition; after the current airflow settling self-cleaning program has completely ended, if there is still a remaining duration of the interrupted pulse heating interference suppression module, the temperature controller will immediately restart the pulse heating interference suppression module to complete the remaining duration; If the timing trigger unit of the pulse heating self-cleaning module reaches the preset trigger time during the execution of the airflow settling self-cleaning program, the temperature controller will not trigger the pulse heating self-cleaning for the time being. After the current airflow settling self-cleaning program is completely finished and the fan speed is restored to the rated value, the pulse heating self-cleaning will be executed immediately. The execution method of the pulse heating self-cleaning, the triggering of the matching pulse heating interference suppression module, the pause and resumption of the moisture content sensor detection signal acquisition, and the probe natural cooling conditions are all the same as those of the pulse heating self-cleaning triggered by the timing trigger unit. The detection signal acquisition of the moisture content sensor returned to normal after the duration of the pulse heating interference suppression module ended and the probe had naturally cooled to the temperature inside the drying chamber. After the pulse heating interference suppression module has finished its duration and the probe has naturally cooled to the temperature inside the drying chamber, if there is no conflict with the airflow settling self-cleaning program, the temperature controller will resume reading the signal from the temperature sensor above the silkworm excrement layer, resume the linkage control based on the dual-channel temperature sensor, and remove the shielding of the real-time temperature difference adjustment function of the vibration adaptive adjustment module.

8. The low-odor, high-efficiency silkworm excrement drying system according to claim 7, characterized in that, The vibration adaptive adjustment module is also equipped with a space frame self-cleaning mode, which is automatically triggered by the temperature controller at preset self-cleaning time intervals. The space frame self-cleaning mode is only allowed to be started when the airflow settling self-cleaning program is not executed, the real-time temperature difference adjustment function of the vibration adaptive adjustment module is not disabled, and the pulse heating interference suppression module is not in an active state. If the preset self-cleaning time interval is reached and the space frame self-cleaning mode is not started due to any of the above conditions not being met, it will be executed once immediately after all conditions are met. After the self-cleaning mode of the space frame is activated, the following operations are performed: The vibration adaptive adjustment module switches the phase angle difference between the two vibration motors from 0° to 180° through the frequency converter, causing the thin-layer breathable load-bearing space frame to generate horizontal reciprocating rubbing vibration for 5 to 10 seconds, and then restores the phase angle difference to 0°; During the operation of the self-cleaning mode of the space frame, the real-time temperature difference adjustment function of the vibration adaptive adjustment module is temporarily disabled, the vibration frequency remains unchanged at the current value, and the amplitude remains between 0.5mm and 2.0mm; If the airflow settling self-cleaning procedure is triggered during the operation of the space frame self-cleaning mode, the vibration adaptive adjustment module will immediately stop the space frame self-cleaning mode, restore the phase angle difference to 0°, and after the airflow settling self-cleaning procedure ends, if the pulse heating interference suppression module is not in an active state at this time, the remaining duration of the space frame self-cleaning mode will be immediately re-executed; if the pulse heating interference suppression module is in an active state, the mode will be re-executed immediately after the module ends. If the pulse heating self-cleaning module is triggered during the operation of the space frame self-cleaning mode, the vibration adaptive adjustment module immediately stops the space frame self-cleaning mode, restores the phase angle difference to 0°, and allows the pulse heating self-cleaning module to perform normally. After the pulse heating self-cleaning and interference suppression modules have all been executed, the remaining time of the grid self-cleaning mode will be immediately re-executed.

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