Greenhouse closed-loop energy-saving heat supply system based on biological waste fermentation

Abstract

The invention discloses a greenhouse closed-loop energy-saving heat supply system based on biological waste fermentation, and relates to the crossing field of agricultural intelligent planting and waste resource utilization, the system comprises the following components: a fermentation unit, a biogas collection and utilization module, a waste heat and fertilizer recovery module and an intelligent management and control system; biogas is generated through fermentation of biological waste, heat generated by combustion of the biogas is used for supplying heat to a greenhouse and a living room, meanwhile, waste heat generated in the fermentation process is recycled for auxiliary heat supply, and the energy utilization efficiency is remarkably improved; according to the invention, residues after fermentation can be converted into a decomposed organic fertilizer for greenhouse crops to use, so that cyclic utilization of resources is realized, the use amount of chemical fertilizer is reduced, the production cost is reduced, and meanwhile, environmental protection is facilitated.

Description

Technical Field

[0001] This invention relates to the intersection of smart agricultural planting and waste resource utilization, specifically a closed-loop energy-saving heating system for greenhouses based on the fermentation of biological waste. Background Technology

[0002] With the escalating global energy crisis and the increasing demand for sustainable agricultural development, how to achieve high efficiency, energy conservation, and resource recycling in agriculture has become a critical issue that urgently needs to be addressed. In particular, in greenhouse cultivation, how to effectively utilize agricultural waste, reduce dependence on traditional energy sources, and improve crop yield and quality is an important direction for current agricultural technology development.

[0003] Traditional greenhouse heating technologies mainly rely on fossil fuels such as coal and natural gas. These energy sources are not only expensive, but also produce large amounts of greenhouse gases and pollutants during combustion, causing serious environmental impacts. At the same time, the use of fertilizers in traditional greenhouse cultivation often results in excessive or insufficient application, leading to resource waste and environmental pollution. In addition, traditional greenhouse environmental control relies heavily on manual operation, making it difficult to achieve precise management and resulting in unstable crop growth conditions, affecting yield and quality. Especially in cold winter regions such as southern Xinjiang, traditional heating methods cannot meet the needs of greenhouses for long-term, stable heating, which restricts crop growth and reduces economic benefits.

[0004] In summary, traditional greenhouse heating and agricultural waste treatment technologies suffer from problems such as high energy consumption, significant pollution, low resource utilization, and insufficient control precision. Therefore, the development of a closed-loop energy-saving heating system for greenhouses based on biological waste fermentation is of particular importance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a closed-loop energy-saving heating system for greenhouses based on the fermentation of biological waste. This system can generate biogas through the fermentation of biological waste, and use the combustion of biogas and the waste heat from fermentation to heat the greenhouse. At the same time, the fermentation residue is recycled as organic fertilizer, achieving efficient energy utilization and resource recycling. Compared with traditional technologies, this system not only significantly reduces energy consumption and environmental pollution, but also achieves precise control of the greenhouse environment and optimized management of crop growth through an intelligent control system, improving crop yield and quality, and providing strong support for the sustainable development of greenhouse cultivation.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a closed-loop energy-saving heating system for greenhouses based on bio-waste fermentation, the system comprising the following components: a fermentation unit, a biogas collection and utilization module, a waste heat and fertilizer recovery module, and an intelligent control system; The fermentation unit is a sealed fermentation tank with an insulation layer made of modified polyurethane composite insulation material. The tank is used to contain a mixture of biological excrement and weed waste. It is equipped with a temperature control module, a staged oxygen supply device, a pH sensor, and a harmful anaerobic bacteria concentration sensor. The staged oxygen supply device is a combination of a ring aeration disc and a variable frequency blower, which can control the fermentation temperature to change in a gradient of 25℃→55℃→75℃→50℃ and maintain an effective temperature period of 3 months. The biogas collection and utilization module includes a biogas storage tank, a biogas burner, and a carbon dioxide conveying unit. The carbon dioxide conveying unit is equipped with a two-stage purification device. The heat generated by the biogas burner is supplied to the greenhouse and the living quarters respectively. The carbon dioxide generated by combustion is treated by the two-stage purification device and then transported to the greenhouse as gas fertilizer. The waste heat and fertilizer recovery module includes heat exchange tubes nested in the outer wall of the fermentation tank. The heat exchange tubes are arranged in a spiral pattern and coated with a nano-thermal conductive coating. The heat exchange system is equipped with a diversion valve and an automatic descaling device for recovering fermentation waste heat to assist in heating. A fertilizer discharge device is provided at the bottom of the fermentation tank for discharging well-rotted organic fertilizer after fermentation. The intelligent management and control system adopts a dual-mode architecture of local control + remote cloud platform, including a controller, multiple types of sensors and actuators. The actuators include greenhouse curtain motors and integrated water and fertilizer equipment. The sensors include temperature sensors, oxygen sensors, CO2 concentration sensors, crop growth monitoring sensors, photosynthetically active radiation sensors, light sensors, and wind speed sensors. The controller has built-in fermentation temperature control algorithms, crop growth stage identification and water and fertilizer control algorithms, and links the operating parameters of each unit to achieve unattended operation throughout the entire process. The system is also equipped with a data encryption module and a fault early warning mechanism.

[0007] Furthermore, the electric heating power of the temperature control module in the fermentation unit is dynamically adjusted by a precise fermentation temperature control algorithm built into the intelligent control system. The algorithm formula is as follows: ,in This refers to the output power of the electric heating device. The weighting coefficients for the fermentation stages are determined based on orthogonal experimental data from the fermentation of a 3:1 mixture of biological manure and weeds in southern Xinjiang. These values ​​are used during days 1-30 of fermentation. Days 31-60 On days 61-90 , This is the difference between the target temperature and the real-time temperature. This is the material moisture content correction factor, calculated based on the measured material moisture content. The formula is: ,in The real-time moisture content of the material, ranging from 55% to 65%, was determined through 10 comparative experiments on fermentation heat yield with different moisture contents. This coefficient is used to correct for the influence of moisture content on the heat of fermentation. The oxygen concentration correction factor is calculated based on the real-time oxygen concentration within the fermentation unit, and the formula is as follows: ,in The oxygen concentration inside the tank ranges from 5% to 8%. This coefficient was determined through five sets of fermentation temperature variation experiments under different oxygen concentrations and is used to coordinate and match oxygen supply and heating efficiency. This algorithm can improve the fermentation temperature control accuracy to ±0.3℃, ensuring the stable maintenance of the effective temperature period of 3 months and solving the problem of fermentation temperature runaway caused by environmental temperature fluctuations in southern Xinjiang during winter and spring.

[0008] Furthermore, the oxygen supply parameters of the staged oxygen supply device in the fermentation unit are precisely controlled through a dynamic adjustment strategy. Specifically, from day 1 to day 7 of fermentation, oxygen is supplied three times a day based on fermentation temperature data and the pH value of the material collected by the pH sensor built into the fermentation unit, with each oxygen supply lasting for a certain duration. Oxygen supply intensity ,in For the real-time pH value of the material, To maintain real-time fermentation temperature, oxygen was supplied once every 3 days during days 8-90 of fermentation, with each oxygen supply lasting for [duration not specified]. Oxygen supply intensity ,in This refers to the fermentation days; the baseline values ​​for the above oxygen supply parameters were determined through inhibition tests on harmful anaerobic bacteria native to southern Xinjiang. When the harmful anaerobic bacteria concentration sensor built into the fermentation unit detects a concentration ≥10... 3 When CFU / g is reached, the emergency oxygen supply mode is automatically triggered, increasing the oxygen supply intensity by 50% and extending the oxygen supply duration to 1.5 times the original duration. This ensures that the kill rate of harmful anaerobic bacteria is maintained above 95%, while avoiding the decline in fermentation efficiency caused by excessive oxygen supply. This solves the pain point that the traditional fixed oxygen supply mode cannot adapt to the needs of different stages of fermentation.

[0009] Furthermore, the insulation layer of the fermentation unit is 120mm thick with a thermal conductivity ≤0.025W / (m·K), and is wrapped with an aluminum foil reflective film to reduce heat loss caused by low outdoor temperatures in southern Xinjiang during winter. The heat exchange tubes of the waste heat and fertilizer recovery module have a spacing of 150mm, a diameter of DN32, and a nano-thermal conductive coating with a thermal conductivity ≥400W / (m·K) to improve the heat transfer efficiency of fermentation. The diversion valve of the heat exchange system dynamically distributes the fermentation waste heat and biogas in the biogas collection and utilization module through an intelligent control system. The proportion of heat supplied by the gas burner is as follows: when the fermentation temperature is ≥55℃, the proportion of fermentation waste heat supply is ≥60%; when the fermentation temperature is <55℃, the proportion of biogas combustion heat supply is ≥70%. The automatic descaling device of the heat exchange system adopts ultrasonic vibration descaling with a vibration frequency of 20-40kHz. The regular descaling cycle is once a week for 15 minutes each time, which avoids the decrease in heat exchange efficiency caused by the adhesion of fermentation residue and ensures that the waste heat recovery rate is maintained above 85%, thus solving the technical pain point of large heat loss in the fermentation system under the low temperature environment in winter in southern Xinjiang.

[0010] Furthermore, the carbon dioxide delivery unit in the biogas collection and utilization module is equipped with a concentration-coordinated regulation mechanism. This mechanism dynamically adjusts the delivery rate based on changes in the photosynthetic rate of crops within the greenhouse and the CO2 concentration. Specifically, it uses a photosynthetically active radiation sensor in the intelligent control system to collect the intensity of photosynthetically active radiation within the greenhouse. , combined Real-time concentration collected by concentration sensor ,calculate Supply ,in The photosynthetic coefficient of crops. For optimal crop Concentration, the Based on field trial data of major greenhouse crops in southern Xinjiang, it was determined that when planting tomatoes... When planting chili peppers When cucumbers are planted By comparing three crops under different conditions... The photosynthetic rate under different concentrations of photosynthetically active radiation was monitored and obtained using nonlinear regression analysis. Adjust dynamically according to crop growth stages, seedling stage Flowering period Results period ,at the same time Before being transported, the material undergoes activated carbon adsorption and molecular sieve filtration in the secondary purification unit of the carbon dioxide transport unit to remove sulfides and particulate matter produced by biogas combustion, thus avoiding damage to crops. The resistance loss of the purification unit is controlled within 500Pa to ensure transport efficiency. This mechanism achieves precise matching between CO2 fertilizer supply and crop needs, increasing photosynthetic efficiency by more than 30%, while avoiding crop growth inhibition caused by excessive CO2 accumulation.

[0011] Furthermore, the crop growth stage identification and fertigation precision control algorithm built into the intelligent control system is used to dynamically adjust the nitrogen, phosphorus, and potassium ratio and irrigation volume of the fertigation equipment in the actuator. The algorithm formula is as follows: ,in The crop growth index, Normalized Difference Vegetation Index (NDVI) The ratio is the vegetation index. The greenness normalized vegetation index (NRVI) is calculated using crop growth monitoring sensors within the intelligent management and control system. , , The weighting coefficients were determined using stepwise regression analysis based on field trial data of greenhouse crops in southern Xinjiang. , , The experiment covered three key stages: seedling stage, flowering stage, and fruiting stage. At each stage, 100 sets of multispectral data and corresponding crop growth status indicators were collected. Correlation analysis was used to determine the weight of each index. The time was determined to be the seedling stage, the water-fertilizer ratio was 2:1:1, and the irrigation amount was... , For reference crop evapotranspiration, when The time is determined to be the flowering period, the water-fertilizer ratio is 1.5:1:1.5, and the irrigation amount is... ,when The time was determined to be the fruiting period, the water-fertilizer ratio was 1:0.5:1.2, and the irrigation amount was... , Data is collected by sensors measuring temperature, humidity, and wind speed inside the greenhouse. The algorithm is then modified and calculated based on the Penman-Monteith formula to adapt to the arid and rain-scarce climate of southern Xinjiang. This algorithm achieves precise matching between crop growth needs and water and fertilizer supply, increasing water and fertilizer utilization by more than 40% and reducing water and fertilizer waste.

[0012] Furthermore, the greenhouse curtain motor in the actuator of the intelligent control system is linked with the intelligent control system, adopting a dual-parameter collaborative control logic of light and temperature. Specifically, the real-time light intensity outside the greenhouse is collected by the light sensor of the intelligent control system. Combined with the real-time temperature inside the greenhouse The operation of the roller shutter is dynamically adjusted according to the crop growth stage; when the seedling stage is determined, the roller shutter opening threshold is set. , turn off threshold ,like °C, then the threshold is lowered to To avoid strong sunlight and high temperatures causing seedlings to grow excessively tall; when the flowering period is determined, the roller shutter opening threshold should be set. , turn off threshold ,like Then the threshold for closing will be increased to To ensure stable temperature during the flowering period; when the fruiting period is determined, the roller shutter opening threshold is adjusted. , turn off threshold ,like If the threshold is lowered to 7000 lux, the greenhouse ventilation opening will be opened simultaneously; the response delay of the roller shutter action is ≤3 seconds, the running speed can be adjusted, and the position of the roller shutter is fed back in real time through the encoder, with a positioning accuracy of ±5cm; this control logic realizes the coordinated optimization of light utilization and temperature control, which improves crop photosynthetic efficiency by more than 25%, while avoiding the impact of extreme environments on crop growth.

[0013] Furthermore, the intelligent control system is equipped with a harmful anaerobic bacteria concentration monitoring and oxygen supply feedback regulation mechanism, using an electrochemical anaerobic bacteria sensor built into the fermentation unit to collect the concentration of harmful anaerobic bacteria in the fermenter in real time. The oxygen supply strategy is dynamically adjusted based on the staged oxygen supply parameters of the fermentation unit's staged oxygen supply device; when When, maintain the original oxygen supply parameters; when At that time, the oxygen supply intensity will be increased by 30%, and the oxygen supply frequency will be increased by 50%. When the emergency oxygen supply mode is activated, the oxygen supply intensity is increased by 80%. Simultaneously, the temperature control module of the fermentation unit temporarily raises the fermentation temperature by 5°C. This high temperature and high oxygen synergy inhibits the growth of harmful anaerobic bacteria. The concentration threshold for harmful anaerobic bacteria is determined through the Southern Xinjiang Organic Fertilizer Fermentation Hygiene Standard Test, ensuring that the content of harmful anaerobic bacteria in the final decomposed organic fertilizer discharged through the bottom fertilizer discharge device of the fermentation unit is ≤10%. 2 CFU / g; This mechanism enables precise control of harmful anaerobic bacteria, avoiding the risk of crop diseases caused by excessive harmful bacteria during traditional fermentation, and improving the safety of organic fertilizer products.

[0014] Furthermore, the intelligent management and control system adopts a dual-mode architecture of local control + remote cloud platform. The local controller uses a PLC, supporting offline autonomous operation, while the remote cloud platform achieves data transmission through the MQTT communication protocol, supporting real-time monitoring via mobile APP and computer. The system's data encryption module uses the AES-256 encryption algorithm to encrypt sensor data and control commands during transmission, preventing data leakage. The system's fault early warning mechanism is triggered by conditions including a fermentation temperature deviation of ≥2℃ in the fermentation unit, an oxygen supply pressure of ≤0.05MPa in the fermentation unit's staged oxygen supply device, a CO2 concentration of ≥2000ppm or ≤500ppm in the biogas collection and utilization module, and abnormal pressure in the water and fertilizer pipeline of the integrated water and fertilizer equipment. Upon triggering, a graded early warning is automatically initiated, and emergency handling procedures are executed in conjunction with the system. The system supports historical data storage and data analysis functions. Through big data analysis, the fermentation parameters of the fermentation unit and the water and fertilizer ratio of the integrated water and fertilizer equipment are optimized to continuously improve the system's operating efficiency and ensure the stability and reliability of the entire process without human intervention.

[0015] Compared with existing technologies, this closed-loop energy-saving heating system for greenhouses based on bio-waste fermentation has the following advantages: I. This system produces biogas through the fermentation of biological waste, and uses the heat generated by burning the biogas to heat greenhouses and living quarters. At the same time, it recovers the waste heat generated during the fermentation process for auxiliary heating, which significantly improves energy efficiency. In addition, the system is equipped with a waste heat and fertilizer recovery module, which can convert the residue after fermentation into well-rotted organic fertilizer for use by greenhouse crops, realizing the recycling of resources, reducing the amount of chemical fertilizer used, lowering production costs, and benefiting environmental protection.

[0016] II. This system adopts a dual-mode architecture of local control and remote cloud platform through its built-in intelligent management and control system. It integrates multiple types of sensors and actuators, enabling real-time monitoring and regulation of environmental parameters and crop growth status within the greenhouse. Through built-in algorithm models, the system can dynamically adjust the nitrogen, phosphorus, and potassium ratio and irrigation volume of the integrated water and fertilizer equipment, achieving precise matching between crop growth needs and water and fertilizer supply, improving water and fertilizer utilization, and promoting healthy crop growth. At the same time, the intelligent management and control system also has a fault early warning mechanism, which can promptly detect and handle abnormal situations in system operation, ensuring the stability and reliability of the entire unattended operation of the system.

[0017] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a flowchart of the operation of a closed-loop energy-saving heating system for greenhouses based on bio-waste fermentation. Figure 2 This is an overall flow chart of a closed-loop energy-saving heating system for greenhouses based on the fermentation of biological waste. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0021] Example 1 In southern Xinjiang, outdoor temperatures can reach -15℃ in December, with large diurnal temperature variations. Tomato seedlings have stringent environmental requirements, needing a stable greenhouse temperature of 18-25℃, a suitable CO2 concentration of 800-1200ppm, and gentle light. Simultaneously, it's crucial to prevent the growth of harmful anaerobic bacteria within the fermentation unit, which could negatively impact heat production efficiency and organic fertilizer quality. Therefore, this closed-loop energy-saving heating system based on bio-waste fermentation requires continuous, coordinated operation across all units to meet the needs of tomato seedlings while simultaneously achieving resource utilization of bio-waste and energy-efficient heating. Figure 1 As shown.

[0022] After the system is started, pre-treated biological waste mixed with weeds is first loaded into the sealed fermentation tank of the fermentation unit. The insulation layer on the outer wall of the tank immediately comes into play. This insulation layer is made of modified polyurethane composite insulation material, with a thickness of 120mm and a thermal conductivity of ≤0.025W / (m·K). The outer layer is also wrapped with an aluminum foil reflective film. Its core function is to block the exchange of heat between the tank and the low temperature outside, greatly reducing the heat loss caused by the low outdoor temperature in southern Xinjiang in winter. This provides a stable temperature environment for the fermentation of biological waste in the tank and avoids the impact of temperature fluctuations on microbial activity. Subsequently, the tank temperature control module, the staged oxygen supply device, the pH sensor, and the harmful anaerobic bacteria concentration sensor are activated simultaneously. The activation function of these devices is to collect key parameters in real time during the fermentation process, providing data support for subsequent precise control.

[0023] like Figure 2As shown, the intelligent management and control system simultaneously adopts a dual-mode architecture of local control and remote cloud platform. The local controller uses a PLC and supports offline autonomous operation. This design ensures that the system can still operate normally even in the event of a network interruption, avoiding loss of control of the seedling environment due to communication problems. The remote cloud platform realizes data transmission through the MQTT communication protocol and supports real-time monitoring on mobile APP and computer. Its function is to facilitate managers to remotely view the system's operating status and grasp key information without on-site supervision. The system's data encryption module uses the AES-256 encryption algorithm to encrypt the raw data collected by the sensors and the control commands issued, preventing data from being stolen or tampered with during transmission and ensuring the security and privacy of the system's operating data.

[0024] During days 1-7 of fermentation, the staged oxygen supply device operates according to a dynamic control strategy, supplying oxygen three times daily. The duration and intensity of oxygen supply are flexibly adjusted based on the real-time fermentation temperature and pH value of the material within the tank. This control method aims to match the staged oxygen requirements of microorganisms in the early stages of fermentation, promoting the rapid reproduction of beneficial microorganisms while inhibiting the initial growth of harmful anaerobic bacteria, thus laying the foundation for stable fermentation later. During this period, the intelligent control system dynamically adjusts the electric heating power of the temperature control module through a built-in precise fermentation temperature control algorithm. The formula is: ,in This refers to the output power of the electric heating device. This represents the weighting coefficient for the fermentation stage. This is the correction factor for the moisture content of the material. The oxygen concentration correction coefficient is used in this algorithm to precisely control the electric heating output by combining multiple factors such as fermentation stage, material moisture content, and oxygen concentration. This avoids excessively high or low temperatures caused by relying solely on fixed power, ensuring that the fermentation temperature remains stable within the suitable range of 35-40℃, thereby improving the efficiency and speed of fermentation heat generation. Simultaneously, the waste heat and fertilizer recovery module is activated: the spiral heat exchange tubes nested on the outer wall of the fermenter begin to recover the waste heat generated during fermentation. These heat exchange tubes have a spacing of 150mm, a diameter of DN32, and are coated with a nano-thermal conductive coating. The coefficient is ≥400W / (m·K), which maximizes the recovery of fermentation waste heat and reduces heat waste by increasing the heat conduction area and improving the heat conduction efficiency. The diversion valve of the heat exchange system dynamically allocates the heat supply ratio of fermentation waste heat and biogas collection and utilization module according to the fermentation temperature. At this time, the fermentation temperature is stable at 48℃ (<55℃), and the diversion valve adjusts the proportion of biogas combustion heat supply to ≥70%. The purpose of this ratio setting is to supplement the insufficient waste heat through biogas combustion, ensure the stable heat supply of greenhouse and living room, and avoid the impact of insufficient temperature on the growth of tomato seedlings.

[0025] In the biogas collection and utilization module, the heat generated by the biogas burner is delivered to the greenhouse and living quarters to meet the heating needs of seedling cultivation and daily life. The carbon dioxide produced by combustion is first treated by a secondary purification device to remove impurities such as hydrogen sulfide and dust. This purification step is to prevent harmful impurities from entering the greenhouse and affecting the health of tomato seedlings. The purified carbon dioxide is then delivered to the greenhouse by the carbon dioxide delivery unit according to the CO2 concentration coordinated regulation mechanism. The intelligent control system collects the photosynthetically active radiation intensity in the greenhouse through a photosynthetically active radiation sensor and combines it with the real-time concentration collected by the CO2 concentration sensor. Through this mechanism, the amount of CO2 delivered is dynamically adjusted. Its function is to accurately match the photosynthetic needs of tomatoes during the seedling stage, avoiding excessively high CO2 concentrations that could scorch seedling leaves or excessively low CO2 concentrations that could affect photosynthetic efficiency, and ensuring that seedlings accumulate sufficient organic matter.

[0026] The actuators of the intelligent control system operate in a synchronized manner: the greenhouse curtain motor adopts a dual-parameter collaborative control logic of light and temperature. Targeting the growth characteristics of tomato seedlings, the system presets an opening threshold of 5000 lux and a closing threshold of 2000 lux. This threshold setting aims to provide a gentle light environment for the seedlings, preventing direct sunlight from causing leaf dehydration or scorching. When the real-time temperature inside the greenhouse exceeds 30℃, the system automatically lowers the opening threshold to 4000 lux. This is to increase ventilation and heat dissipation by opening the curtain earlier, preventing excessive seedling growth due to high temperatures inside the greenhouse. Simultaneously, the crop growth stage recognition and water and fertilizer regulation algorithms built into the intelligent control system are activated. The formula is: ,in The crop growth index, Normalized Difference Vegetation Index (NDVI) The ratio is the vegetation index. The greenness normalized vegetation index, , , Using weighted coefficients, this algorithm combines data from multiple types of sensors, including temperature sensors, oxygen sensors, and crop growth monitoring sensors, to dynamically adjust the nitrogen, phosphorus, and potassium ratio and irrigation volume of the integrated water and fertilizer system. Its function is to accurately supply nutrients according to the actual growth status of seedlings, avoiding fertilizer waste or nutrient imbalance caused by blind fertilization. In addition, the automatic descaling device of the heat exchange system operates according to preset parameters, using ultrasonic vibration descaling with a vibration frequency set to 30kHz. Descaling is performed once a week for 15 minutes each time. The purpose of this descaling operation is to remove scale from the inner wall of the heat exchange tube in a timely manner, ensuring that the heat exchange tube continuously and efficiently recovers fermentation waste heat, and avoiding insufficient heat recovery due to scale buildup, which would affect the stability of greenhouse heating.

[0027] During fermentation, a harmful anaerobic bacteria concentration sensor continuously collects real-time data on the concentration of harmful anaerobic bacteria inside the tank. The intelligent control system activates corresponding control measures based on the concentration value: when the concentration of harmful anaerobic bacteria is detected to be <10... 3At CFU / g, maintaining the original oxygen supply parameters helps reduce unnecessary adjustments and save energy when the number of harmful bacteria is low; if the concentration reaches 10... 3 CFU / g≤B<5×10 4 When the concentration is CFU / g, the system automatically increases the oxygen supply intensity by 30% and the oxygen supply frequency by 50%. This measure aims to inhibit anaerobic bacterial respiration and prevent their rapid reproduction by increasing oxygen supply. If the concentration is ≥5×10⁻⁶, the system will automatically increase the oxygen supply intensity by 30% and the oxygen supply frequency by 50%. 4 If the concentration of CFU / g is reached, the emergency oxygen supply mode is immediately activated. This mode quickly inhibits the growth of harmful anaerobic bacteria, preventing them from decomposing waste and producing toxic substances that could affect the quality of organic fertilizer and fermentation heat generation. Simultaneously, the intelligent control system's fault warning mechanism continuously monitors the entire system's operating parameters. When situations arise such as a fermentation temperature deviation ≥2℃ in the fermentation unit, an oxygen supply pressure ≤0.05MPa in the staged oxygen supply device, a CO2 concentration ≥2000ppm or ≤500ppm in the biogas collection and utilization module, or abnormal pressure in the water and fertilizer pipelines of the integrated water and fertilizer equipment, the system automatically activates a tiered warning system and executes emergency procedures. This mechanism promptly detects and addresses system faults, preventing minor issues from escalating into major problems affecting seedling cultivation. Furthermore, the system supports historical data storage and analysis, recording daily data such as temperature, CO2 concentration, and water and fertilizer usage, providing data support for subsequent optimization of seedling cultivation parameters and improvement of system operating efficiency.

[0028] After fermentation, the fertilizer discharge device at the bottom of the fermentation tank is activated, outputting well-rotted organic fertilizer. The purpose of this step is to realize the resource utilization of biological waste, transforming biological excrement and weeds that might otherwise cause pollution into high-quality organic fertilizer, which can be used for fertilization after tomato transplanting, reducing the use of chemical fertilizers. At the same time, it completes the waste-heat-fertilizer cycle, improving the ecological and economic benefits of greenhouse cultivation. Throughout the entire operation, all units work closely together, meeting the harsh environmental requirements of tomato seedling cultivation in southern Xinjiang during winter, and achieving the dual goals of energy-saving heating and resource recovery, ensuring that the seedlings grow vigorously and laying a good foundation for subsequent transplanting and fruiting.

[0029] Example 2 In April, springtime in southern Xinjiang, outdoor temperatures range from 10-25℃. Greenhouse-grown cucumbers enter their fruiting stage, requiring ample sunlight, high CO2 concentrations, precise water and fertilizer supply, and a stable high-temperature environment. The fermentation unit has been running for 30 days and is in the middle of fermentation. The system needs to balance waste heat recovery efficiency, biogas utilization, and the control of harmful anaerobic bacteria. Figure 1 As shown.

[0030] like Figure 2As shown, the system maintains continuous operation, with the mixed waste in the fermentation unit continuously fermenting. The phased oxygen supply device enters the operation mode for days 8-90 of fermentation, supplying oxygen once every 3 days. The duration and intensity of oxygen supply are dynamically adjusted according to the number of fermentation days and the real-time fermentation temperature. The intelligent control system uses built-in algorithms for linkage control. The insulation layer of the fermenter continues to play its role in heat preservation, and the outer aluminum foil reflective film reduces heat loss to the outside. The pH sensor and harmful anaerobic bacteria concentration sensor inside the tank continuously collect data to provide a basis for adjusting oxygen supply parameters and temperature.

[0031] The heat exchange tubes of the waste heat and fertilizer recovery module continuously recover fermentation waste heat. At this time, the fermentation temperature is stable at 60℃≥55℃. The diversion valve of the heat exchange system adjusts the proportion of fermentation waste heat supply to ≥60%, maximizing the use of fermentation waste heat to heat the greenhouse and living quarters. The nano thermally conductive coating on the surface of the heat exchange tubes ensures efficient heat conduction with a thermal conductivity of ≥400W / (m·K). The automatic descaling device of the heat exchange system operates once a week for 15 minutes each time, with the vibration frequency maintained at 20-40kHz. Ultrasonic vibration descaling is used to avoid scale buildup inside the tubes from affecting heat exchange efficiency.

[0032] In the biogas collection and utilization module, the biogas burner provides auxiliary heating based on the waste heat supply. The carbon dioxide produced by combustion is treated by a secondary purification device and then transported to the greenhouse by the carbon dioxide delivery unit according to the concentration coordination and control mechanism. The intelligent management and control system collects the photosynthetically active radiation intensity in the greenhouse through the photosynthetically active radiation sensor, combines it with the real-time data of the CO2 concentration sensor, calculates the CO2 supply through relevant logic, and dynamically adjusts the delivery volume to meet the CO2 demand of cucumber photosynthesis during the fruiting period, thereby improving cucumber yield and quality.

[0033] In the execution mechanism of the intelligent control system, the greenhouse curtain motor operates according to the light-temperature dual-parameter collaborative control logic during the fruiting period. The opening threshold of the curtain is 8000 lux, and the closing threshold is 4000 lux. When the real-time temperature inside the greenhouse exceeds 35℃, the opening threshold is lowered to 7000 lux, and the greenhouse ventilation opening is opened simultaneously to ensure stable temperature for cucumber growth during the fruiting period. The crop growth stage identification and water and fertilizer regulation algorithm runs continuously. Combining data such as normalized vegetation index, ratio vegetation index, and greenness normalized vegetation index, the algorithm calculates the crop growth index and dynamically adjusts the nitrogen, phosphorus, and potassium ratio and irrigation amount of the integrated water and fertilizer equipment to ensure the nutrient supply for cucumbers during the fruiting period.

[0034] The intelligent control system's harmful anaerobic bacteria concentration monitoring and oxygen supply feedback regulation mechanism remains effective. Electrochemical anaerobic bacteria sensors collect real-time data on the concentration of harmful anaerobic bacteria within the fermenter. When a concentration ≥10... 3 When the concentration reaches 5 × 10 CFU / g, the emergency oxygen supply mode is automatically triggered; if the concentration reaches 5 × 10 CFU / g, the emergency oxygen supply mode is triggered. 4For CFU / g and above, in addition to increasing oxygen supply intensity by 80%, the fermentation unit's temperature control module is also activated to temporarily raise the fermentation temperature by 5°C. This high temperature and high oxygen synergy inhibits the growth of harmful anaerobic bacteria. The system's fault warning mechanism monitors various operating parameters in real time. Once a preset fault condition is triggered, a graded warning is immediately activated and an emergency handling procedure is executed. The local controller and the remote cloud platform synchronize fault information and processing progress in real time, and historical data is continuously stored for subsequent review and analysis.

[0035] After 90 days of fermentation, the fertilizer discharge device at the bottom of the fermentation tank outputs decomposed organic fertilizer, which is used as base fertilizer for subsequent crop planting, realizing the recycling of biological waste. The system ensures the stability of the greenhouse environment and energy-saving heating needs throughout the cucumber fruiting period.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A greenhouse closed loop energy efficient heating system based on fermentation of bio-waste, characterized in that, The system comprises the following components: fermentation unit, biogas collection and utilization module, waste heat and fertilizer recovery module, and intelligent management and control system. The fermentation unit is a closed fermentation tank with an insulation layer, the insulation layer uses modified polyurethane composite insulation material, the tank is used to contain biological feces and mixed waste, and is provided with a temperature control module, a phased oxygen supply device, a pH sensor and a harmful anaerobic bacteria concentration sensor, the phased oxygen supply device is a combination structure of a ring-shaped aeration disc and a variable frequency blower; The biogas collection and utilization module comprises a biogas storage tank, a biogas burner and a carbon dioxide delivery unit, the carbon dioxide delivery unit is provided with a two-stage purification device, the heat generated by the biogas burner is supplied to the greenhouse and the living room, and the carbon dioxide generated by combustion is delivered to the greenhouse as gas fertilizer after being treated by the two-stage purification device; The waste heat and fertilizer recovery module comprises heat exchange pipes nested on the outer wall of the fermentation tank, the heat exchange pipes are arranged in a spiral manner and coated with a nano heat-conducting coating, the heat exchange system is provided with a shunt valve and an automatic descaling device, and is used to recover the fermentation waste heat for auxiliary heating, and the bottom of the fermentation tank is provided with a fertilizer discharge device for outputting the decomposed organic fertilizer after fermentation; The intelligent management and control system adopts a local control + remote cloud platform dual-mode architecture, comprises a controller, multiple types of sensors and an execution mechanism, the execution mechanism comprises a greenhouse roller shutter motor and a water and fertilizer integrated device, the sensors comprise a temperature sensor, an oxygen sensor, a CO2 concentration sensor, a crop growth monitoring sensor, a photosynthetically active radiation sensor, a light sensor and a wind speed sensor, the controller is provided with a fermentation temperature control algorithm, a crop growth stage identification algorithm and a water and fertilizer control algorithm, and is used to link and control the operating parameters of each unit, and the system is provided with a data encryption module and a fault early warning mechanism.

2. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, The electric heating power of the temperature regulation module in the fermentation unit is dynamically adjusted by the fermentation temperature precise regulation algorithm built in the intelligent management and control system, and the algorithm formula is: Wherein is the output power of the electric heating device, is the fermentation stage weight coefficient, is the material moisture content correction coefficient, is the oxygen concentration correction coefficient.

3. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, The oxygen supply parameters of the staged oxygen supply device in the fermentation unit are precisely controlled through a dynamic control strategy. Specifically, during the first to seventh days of fermentation, based on the fermentation temperature data and the material pH value collected by the pH sensor built in the fermentation unit, oxygen is supplied three times a day, and the oxygen supply duration , the oxygen supply intensity , wherein is the real-time pH value of the material, is the real-time fermentation temperature, and during the eighth to ninetieth days of fermentation, oxygen is supplied once every three days, and the oxygen supply duration , the oxygen supply intensity , wherein is the fermentation day number; when the harmful anaerobic bacteria concentration sensor built in the fermentation unit detects that the harmful anaerobic bacteria concentration is greater than or equal to 10 3 CFU / g, an emergency oxygen supply mode is automatically triggered.

4. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, The thickness of the insulation layer of the fermentation unit is 120mm, the thermal conductivity is less than or equal to 0.025 W / (m·K), the outer layer is wrapped with an aluminum foil reflection film for reducing heat loss caused by low outdoor temperature in winter in southern Xinjiang, the heat exchange pipe of the waste heat and fertilizer recovery module has a pipe spacing of 150mm and a pipe diameter of DN32, and the nano heat-conducting coating has a thermal conductivity of greater than or equal to 400 W / (m·K); the shunt valve of the heat exchange system dynamically allocates the supply proportion of the fermentation waste heat and the heat generated by the biogas burner in the biogas collection and utilization module, when the fermentation temperature is greater than or equal to 55℃, the supply proportion of the fermentation waste heat is greater than or equal to 60%, and when the fermentation temperature is less than 55℃, the supply proportion of the biogas combustion heat is greater than or equal to 70%; the automatic descaling device of the heat exchange system adopts an ultrasonic vibration descaling mode, the vibration frequency is 20-40kHz, and the regular descaling period is once a week for 15 minutes each time.

5. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, The carbon dioxide conveying unit in the biogas collection and utilization module is provided with a concentration synergistic regulation mechanism, which combines the photosynthesis rate of crops in the greenhouse with the change of CO2 concentration to dynamically adjust the conveying amount, specifically: through the photosynthetically active radiation sensor of the intelligent control system, the photosynthetically active radiation intensity in the greenhouse is collected , combined with the real-time concentration collected by the concentration sensor , the supply amount is calculated , wherein is the photosynthesis coefficient of crops, is the optimal concentration of crops.

6. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, The crop growth stage recognition and water and fertilizer integrated precision regulation algorithm built in the intelligent management and control system is used for dynamically adjusting the nitrogen, phosphorus and potassium ratio and irrigation amount of the water and fertilizer integrated equipment in the execution mechanism, and the algorithm formula is: wherein is a crop growth index, is a normalized vegetation index, is a ratio vegetation index, is a green normalized vegetation index, , , is a weight coefficient.

7. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, The execution mechanism of the intelligent management and control system is linked with the greenhouse roller shutter motor, adopts light-temperature double parameter collaborative control logic, specifically: through the light sensor of the intelligent management and control system, the real-time light intensity outside the greenhouse is collected , combined with the real-time temperature inside the greenhouse and the growth stage of crops, the roller shutter action is dynamically adjusted; when it is determined to be the seedling stage, the opening threshold of the roller shutter is , the closing threshold is , if °C, the opening threshold is lowered to , to avoid the strong light and high temperature leading to the overgrowth of seedlings; when it is determined to be the flowering stage, the opening threshold of the roller shutter is , the closing threshold is , if , the closing threshold is raised to , to ensure the stable temperature in the flowering stage; when it is determined to be the fruiting stage, the opening threshold of the roller shutter is , the closing threshold is , if , the opening threshold is lowered to 7000 lux, and the ventilation opening of the greenhouse is opened at the same time; the response delay of the roller shutter action is ≤3 seconds, the running speed can be adjusted, the position of the roller shutter is fed back in real time through the encoder, and the positioning accuracy is ±5 cm.

8. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, The intelligent management and control system is provided with a harmful anaerobe concentration monitoring and oxygen supply feedback regulation mechanism , adopts an electrochemical anaerobe sensor built in a fermentation unit to collect the harmful anaerobe concentration in the fermentation tank in real time, dynamically adjusts the oxygen supply strategy in combination with the phased oxygen supply parameters of the phased oxygen supply device of the fermentation unit, when , maintains the original oxygen supply parameters, when , increases the oxygen supply intensity by 30% and the oxygen supply frequency by 50%, when , starts the emergency oxygen supply mode, increases the oxygen supply intensity by 80%, and simultaneously links the temperature regulation module of the fermentation unit to temporarily increase the fermentation temperature by 5 DEG C, so as to inhibit the reproduction of harmful anaerobes through high temperature and high oxygen.

9. The bio-waste fermentation based greenhouse closed loop energy efficient heating system according to claim 1, wherein, In the local control + remote cloud platform dual-mode architecture adopted by the intelligent management and control system, the local controller adopts PLC, supports offline autonomous operation, the remote cloud platform realizes data transmission through the MQTT communication protocol, supports real-time monitoring of mobile phone APP and computer terminal; The data encryption module provided by the system uses AES-256 encryption algorithm to encrypt the sensor data and control instructions for transmission; The trigger conditions of the fault early warning mechanism provided by the system include that the fermentation temperature deviation of the fermentation unit is greater than or equal to 2 DEG C, the oxygen supply pressure of the stage oxygen supply device of the fermentation unit is less than or equal to 0.05 MPa, the CO2 concentration of the biogas collection and utilization module is greater than or equal to 2000 ppm or less than or equal to 500 ppm, the water and fertilizer pipeline pressure of the water and fertilizer integrated equipment is abnormal, after triggering, automatically start the hierarchical early warning, and linkage execute emergency treatment program; The system supports historical data storage and data analysis function.

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