Online acquisition device for near infrared transmission spectrum data of anaerobic fermentation biogas slurry

Abstract

The invention provides an STM32-based anaerobic fermentation biogas slurry near infrared transmission spectrum data on-line acquisition device. The device comprises a backwashing anti-blocking biogas slurry filtering system and an on-line liquid near infrared spectrum acquisition system, according to the system, a three-stage filtering mechanism is adopted, an STM32 microcontroller is taken as a core, a miniature optical fiber spectrometer and a halogen tungsten lamp light source are integrated to construct a compact transmission light path, and solid particles in biogas slurry are effectively removed by combining a backwashing anti-blocking T-shaped three-way filter, a double-buffer-bottle liquid level control mechanism and a PID liquid level control strategy; the cavitation phenomenon of a biogas slurry sampling pipeline is inhibited, the stability of sample conveying and the repeatability of spectrum collection are remarkably improved, and an efficient and portable online detection solution is provided for anaerobic fermentation process control; reliable hardware support is provided for application of a near infrared spectrum detection technology in a complex anaerobic fermentation environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of near-infrared spectroscopy detection, in particular to an online near-infrared transmission spectrum data acquisition device for anaerobic fermentation process. BACKGROUND

[0002] Anaerobic fermentation is an effective way to realize resource utilization of organic waste, improve the environment and solve the problem of energy shortage. Anaerobic fermentation state monitoring is an effective strategy to ensure the stable and efficient operation of biogas engineering. Volatile fatty acids, ammonia nitrogen, alkalinity and other anaerobic fermentation liquid phase indicators are the core parameters reflecting the fermentation process. However, the monitoring of the above-mentioned indicators generally relies on offline laboratory analysis, which usually requires manual sampling and measurement by using chromatography, titration and other chemical methods. Although the chemical method has high accuracy, it has serious time lag and cannot provide real-time feedback for process control. At the same time, the cost of manpower and reagents of the chemical method is high, and frequent sampling may damage the system airtightness, leading to distorted monitoring data and system operation risk. In order to solve the shortcomings of offline chemical analysis, near-infrared spectroscopy technology is introduced as a fast and non-destructive analysis method. This technology can indirectly and quickly predict the key components of biogas slurry by detecting the absorption signals of C-H, O-H and other groups in organic matter.

[0003] However, the application of laboratory general spectrometer in online and in-situ monitoring of anaerobic fermentation faces severe challenges. The internal environment of anaerobic fermentation tank is harsh, with corrosion, temperature fluctuation and explosion-proof requirements, so it is difficult for general spectrometer to adapt to long-term stable operation. The composition of anaerobic fermentation slurry is complex, containing a large amount of solid particles and bacteria, which can easily block the pipeline and sample cell of traditional flow cell. If an immersion probe is used, its optical window will be quickly covered by pollutants, resulting in signal attenuation and distortion, and it is difficult to clean and maintain effectively without stopping production. The existing technology lacks special design for high-solid and high-viscosity anaerobic fermentation slurry, and has obvious shortcomings in anti-blocking, anti-pollution and environmental robustness, which makes it difficult to guarantee the reliability and continuity of online monitoring. Therefore, it is very important to develop an online spectrum data acquisition device that can adapt to harsh working conditions, has anti-blocking and anti-pollution ability, and can operate stably for a long time, in order to realize precise monitoring and optimization control of anaerobic fermentation process. SUMMARY

[0004] The application provides an anaerobic fermentation biogas slurry near-infrared transmission spectrum data online acquisition device based on an STM32, and aims to realize stable, real-time and non-destructive online acquisition of anaerobic fermentation biogas slurry near-infrared transmission spectrum data. The device comprises a backwashing anti-blocking biogas slurry filtration system and an online liquid-phase near-infrared spectrum acquisition system. The system takes an STM32 microcontroller as a core, integrates a miniature fiber spectrometer and a halogen tungsten lamp light source to construct a compact transmission light path, and combines a backwashing anti-blocking biogas slurry filtration system, a double-buffer bottle liquid level control mechanism and a PID liquid level control strategy, so that the stability of biogas slurry sample delivery and the repeatability of spectrum acquisition are significantly improved. The application aims at the characteristics of high viscosity, high solid content, easy cavitation and solid impurity interference of biogas slurry in the anaerobic fermentation process, solves the problems of large volume, high power consumption, insufficient sampling stability and impurity interference spectrum quality of a traditional PC-based near-infrared spectrum system through hardware integrated design and PID control, provides an efficient, portable online detection solution for anaerobic fermentation process control, supports real-time monitoring of key indexes such as ammonia nitrogen, volatile fatty acid and alkalinity, avoids process interruption and optimizes fermentation efficiency.

[0005] The technical scheme adopted by the application comprises the following two parts:

[0006] 1. The backwashing anti-blocking biogas slurry filtration system: the system comprises a primary filter screen (1), a T-shaped three-way filter (2), a filtration system external device (3), an STM32 microcontroller (4) and a biogas slurry temporary storage bottle (5); wherein the filtration system external device (3) comprises a cross variable-diameter pipeline (302), peristaltic pumps (301, 304, 308), electromagnetic valves (303, 305, 306, 307), a liquid level sensor (309) and a communication line (310);

[0007] The system ensures effective removal of solid particles in biogas slurry and long-term stable operation of the system through a three-stage filtering mechanism and backwashing anti-blocking design. A three-stage filtering system is added between the anaerobic fermentation tank (0) and the near-infrared spectrum acquisition device. First, the filter screen (1) attached to the side wall of the biogas slurry tank is the first stage of filtration, which is used to remove large solid impurities. Then the second stage of filtration uses a T-shaped three-pass filter (2). Its "up-in, up-out, up-in, down-out" structure can achieve efficient biogas slurry filtration and backwashing anti-blocking. Its advantage lies in the full use of the synergistic effect of fluid dynamics and gravity. During normal filtration, the biogas slurry enters horizontally from the left side of the inlet, penetrates vertically through the built-in filter screen, and then flows out smoothly from the right side of the outlet, avoiding excessive accumulation of solid particles on the screen surface. When the system enters the discharge state, the biogas slurry is reversely pumped from the outlet at high pressure, rapidly filling the filter cavity and forming a downward vortex, which drives the retained particles to be flushed out from the bottom of the outlet, completely removing the blockage in the filter holes. This design does not require additional backwashing pumps or complex valve groups to achieve self-cleaning circulation, with high flushing efficiency, few dead angles, low liquid consumption, and maintained filtering precision, ensuring consistent removal of solid particles from the biogas slurry before spectrum sampling during long-term operation, significantly extending the maintenance-free period of the system. The filtered biogas slurry is sent to the near-infrared spectrum acquisition system through the biogas slurry temporary storage bottle (5), with a Y-shaped filter (6) added as the third stage of filtration to ensure the removal of solid particles in the biogas slurry entering the cuvette. The extraction, filtration, and circulation of the biogas slurry are controlled by the STM32 microcontroller (4) to reduce the interference of solid impurities on spectrum acquisition. The biogas slurry temporary storage bottle (5) has two pairs of liquid inlets and outlets. Based on the principle of material balance, a second-order transfer function model of the biogas slurry temporary storage bottle system is constructed, considering the liquid resistance of the inlet pipeline, the capacity coefficient of the temporary storage bottle, and the transmission time delay, quantifying the capacity lag to simulate the flow state of the filtered biogas slurry. The liquid level is monitored in real time by the liquid level sensor (309), and the speed of the inlet peristaltic pump (301, 304) is adjusted by combining the PWM controller and the PID control algorithm to ensure the continuity and stability of the filtration process.

[0008] 2. Online liquid-phase near-infrared spectrum acquisition system: the system includes a Y-shaped filter (6), an STM32 microcontroller (7), a spectrum data online acquisition peripheral (8), an upper computer (9), a cuvette and support (10), a miniature spectrometer (11), and a high-power halogen light source (12). The spectrum data online acquisition peripheral (8) includes a peristaltic pump (801, 812), an electromagnetic valve (802, 811, 813), a standard SMA905 optical fiber (803, 808), a double-buffered bottle (804, 805), a liquid level sensor (806, 807), a USB data line (809, 814), and a check valve (810).

[0009] The system adopts a double-buffer bottle structure matched with PID liquid level closed-loop control, effectively reduces the pipeline cavitation risk in the transportation of high-viscosity biogas slurry, and realizes the filtration and extraction of the biogas slurry by using STM32 control backwashing anti-blocking system peripherals and near-infrared spectrum acquisition system peripherals. A compact, low-power online spectrum data acquisition system is constructed by integrating a miniature spectrometer and a high-power halogen light source, and the shortcomings of traditional offline chemical analysis are overcome. A multi-stage biogas slurry filtration system and a temporary storage bottle liquid level control model are added, which effectively removes solid impurities in the biogas slurry and maintains the liquid level stability during the filtration process, and improves the spectrum data quality. The double-buffer bottle is combined with a liquid level sensor and PID closed-loop control to suppress the cavitation phenomenon of the biogas slurry sampling pipeline, and improve the sample delivery stability and the repeatability of the transmission spectrum acquisition. The system supports real-time communication, and can monitor the dynamic changes of the anaerobic fermentation process in real time. The system design is flexible, and provides reliable hardware support for the application of near-infrared spectrum technology in complex fermentation environment.

[0010] Compared with the prior art, the present application has the following advantages:

[0011] The present application uses STM32 to control the backwashing anti-blocking system peripherals and near-infrared spectrum acquisition system peripherals to filter and extract the biogas slurry, and integrates a miniature spectrometer and a high-power halogen light source to construct a compact, low-power online spectrum data acquisition system, which overcomes the shortcomings of traditional offline chemical analysis. A multi-stage biogas slurry filtration system and a temporary storage bottle liquid level control model are added, which effectively removes solid impurities in the biogas slurry and maintains the liquid level stability during the filtration process, and improves the spectrum data quality. The double-buffer bottle is combined with a liquid level sensor and PID closed-loop control to suppress the cavitation phenomenon of the biogas slurry sampling pipeline, and improve the sample delivery stability and the repeatability of the transmission spectrum acquisition. The system supports real-time communication, and can monitor the dynamic changes of the anaerobic fermentation process in real time. The system design is flexible, and provides reliable hardware support for the application of near-infrared spectrum technology in complex fermentation environment. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0013] Figure 1 is a schematic diagram of the overall structure of the present application;

[0014] Figure 2 is a detailed structure schematic diagram of the present application;

[0015] Figure 3 is a plan view of the cuvette support;

[0016] In this diagram, 0 represents the anaerobic digester, 1 the filter screen, 2 the T-type three-way filter, 3 the peripherals of the filtration system (where 301, 304, and 308 are peristaltic pumps of the biogas slurry filtration system, 302 is a cross-shaped reducing pipe, 303, 305, 306, and 307 are solenoid valves of the biogas slurry filtration system, 309 is a level sensor for the biogas slurry storage bottle, and 310 is the communication line for the STM32 microcontroller), 4 the STM32 microcontroller of the filtration system, 5 the biogas slurry storage bottle, 6 the Y-type filter, 7 the STM32 microcontroller of the near-infrared spectral acquisition system, and 8 the peripherals for online spectral data acquisition (where 801 and 812 are near-infrared...). The peristaltic pump of the spectral acquisition system; 802, 811, and 813 are solenoid valves of the near-infrared spectral acquisition system; 803 and 808 are standard SMA905 optical fibers; 804 and 805 are biogas slurry buffer bottles; 806 and 807 are biogas slurry buffer bottle level sensors; 809 is the spectrometer USB data cable; 810 is a check valve; 814 is an STM32 microcontroller communication cable; 9 is the host computer; 10 is the cuvette and its support (where 1001 is the cuvette support, 1002 is the cuvette, 1003 is the right fiber collimator, and 1004 is the left fiber collimator); 11 is the miniature spectrometer; and 12 is the high-power halogen light source. Detailed Implementation

[0017] To make the above-mentioned objectives, features and advantages of the present invention more readily understood, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, the online acquisition device for near-infrared transmission spectral data of anaerobic fermentation biogas slurry of the present invention includes a backwashing and anti-clogging biogas slurry filtration system and an online liquid phase near-infrared spectral acquisition system;

[0019] The backwashing anti-blocking biogas slurry filtration system is composed of an anaerobic fermentation tank (0), a filter screen (1), a T-shaped three-pass filter (2), a filtration system peripheral (3), an STM32 microcontroller (4), and a biogas slurry temporary storage bottle (5), and a real-time communication channel is built between the STM32 microcontroller (4) of the filtration system and the STM32 microcontroller (7) of the spectrum acquisition system. The STM32 controls the filtration system peripheral to extract the biogas slurry in the anaerobic fermentation tank (0), and the filter screen (1) attached to the outlet of the anaerobic fermentation tank filters the large particles in the biogas slurry. The T-shaped three-pass filter (2) has a liquid inlet, a liquid outlet, and a liquid discharge outlet. The biogas slurry filtered by the filter screen (1) enters the filter through the liquid inlet, and the small particles in the biogas slurry are filtered by the filter screen built in the T-shaped three-pass filter (2), and then the biogas slurry after secondary filtration is sent to the biogas slurry temporary storage bottle (5) through the liquid outlet. The STM32 microcontroller (4) acquires the liquid level of the biogas slurry in the biogas slurry temporary storage bottle (5) in real time, and adjusts the speed of the peristaltic pump (301, 304) in the filtration system peripheral through the PID liquid level controller to realize stable liquid level.

[0020] The near-infrared spectrum acquisition system is composed of a Y-shaped filter (6), an STM32 microcontroller (7), a spectrum data online acquisition peripheral (8), a host computer (9), a cuvette and support (10), a miniature near-infrared spectrometer (11), and a high-power halogen light source (12). The STM32 microcontroller (7) builds a real-time communication channel with the host computer (9) through a serial port. The STM32 microcontroller (7) of the spectrum acquisition system determines whether it can currently collect biogas slurry through the real-time communication channel with the STM32 microcontroller (4) of the filtration system. If it can collect, the STM32 microcontroller (7) controls the spectrum data online acquisition peripheral (8) to extract the biogas slurry in the biogas slurry temporary storage bottle (5). The biogas slurry flows through the Y-shaped filter (6) with an 80-mesh filter screen built in, which can filter out the fine particles contained therein. The STM32 microcontroller (7) acquires the liquid level value of the liquid level sensor (806, 807) in the spectrum data online acquisition peripheral (8) in real time, and adjusts the speed of the peristaltic pump (812) in the online acquisition peripheral (8) through the PID liquid level controller to prevent the phenomenon of pipeline cavitation. When the biogas slurry fills the cuvette (1002) and reaches the preset liquid level, the STM32 microcontroller (7) returns the information to the host computer (9) through the real-time communication channel, and determines that it is currently in a state of collecting near-infrared transmission spectrum data.

[0021] When the host computer (9) controls the micro near-infrared spectrometer (11) to complete the spectrum data collection of biogas slurry, it sends a sample arrangement signal to the STM32 microcontroller (7) of the near-infrared spectrum collection system through the real-time communication channel. The STM32 microcontroller (7) of the near-infrared spectrum collection system controls the spectrum data online collection peripheral (8) to discharge the biogas slurry in the pipeline to the biogas slurry temporary storage bottle (5), and sends the current sample arrangement state to the STM32 microcontroller (4) of the biogas slurry filtering system through the real-time communication channel. The STM32 microcontroller (4) of the biogas slurry filtering system controls the filtering system peripheral (3) to extract the biogas slurry from the liquid discharge port to the anaerobic fermentation tank (0), completes the sampling cycle, and flushes the small particle substances retained in the T-shaped three-pass filter (2), avoiding the accumulation caused by long-term circulation.

[0022] As shown in Figure 2 The present application is composed of an anaerobic fermentation tank (0), a filter screen (1), STM32 microcontrollers (4, 7), a micro spectrometer (11), a halogen light source (12), peristaltic pumps (301, 304, 308, 801, 812), electromagnetic valves (303, 305, 306, 307, 802, 811, 813), a biogas slurry temporary storage bottle (5), a cross variable-diameter pipeline (302), a T-shaped three-pass filter (2), a Y-shaped filter (6), a one-way valve (810), wall-adhesion type liquid level sensors (309, 806, 807), a host computer (9), and other peripheral devices. The host computer (9) is communicatively connected with the micro spectrometer (11) and the STM32 microcontroller (7), and the STM32 microcontroller (7) is communicatively connected with the STM32 microcontroller (4). The liquid level sensor (309) is communicatively connected with the STM32 microcontroller (4) through an I2C serial port, and the liquid level sensors (806, 807) are communicatively connected with the STM32 microcontroller (7) through an I2C serial port.

[0023] The online collection device of anaerobic fermentation biogas slurry near-infrared transmission spectrum data sends "spectrum data collection instruction" to STM32 microcontroller (7) through RS485 serial port of upper computer (9) to start running by applying Modbus protocol, and then carries out real-time communication and continuously inquires whether spectrum data can be collected. After receiving the instruction, STM32 microcontroller (7) sends "start filtering biogas slurry" communication information to STM32 microcontroller (4) through RS485 serial port by applying Modbus protocol, and then carries out real-time communication and continuously inquires whether sample can be collected. STM32 microcontroller (4) judges whether the liquid level in the current biogas slurry temporary storage bottle (5) is at the preset liquid level by collecting the liquid level of the liquid level sensor (309) in real time, and if the current liquid level does not reach the preset liquid level, the peristaltic pump (301, 304, 801) is started in forward rotation, and the electromagnetic valve (305, 802) is opened to extract the biogas slurry in the anaerobic fermentation tank (0), in order to ensure the continuity of the filtering process, the biogas slurry temporary storage bottle liquid level PID controller is constructed to control the rotation speed of the peristaltic pump (301, 304, 801). When the liquid level in the biogas slurry temporary storage bottle (5) reaches the preset liquid level, the peristaltic pump (301, 304, 801) is stopped, the electromagnetic valve (305, 802) is closed, and the communication information "sample can be collected" is returned to STM32 microcontroller (7).

[0024] After receiving the information, STM32 microcontroller (7) collects the liquid level of the liquid level sensor (806, 807) in real time, starts the peristaltic pump (304, 812) in forward rotation, opens the electromagnetic valve (303, 305, 813) to extract the biogas slurry in the biogas slurry temporary storage bottle, and judges whether the liquid level in the current buffer bottle (804, 805) is at the preset liquid level, in order to reduce the pipeline cavitation phenomenon in the extraction process, the double-buffer bottle liquid level PID controller is constructed to control the rotation speed of the peristaltic pump. When the biogas fills the cuvette (1002) and the liquid level reaches the preset liquid level of the double-buffer bottle, the peristaltic pump (304, 812) is stopped, the electromagnetic valve (303, 305, 813) is closed, and the communication information "spectrum data can be collected" is returned to the upper computer (9), and then the instruction of the upper computer (9) is waited. In order to reduce the influence of impurities in the biogas slurry on the quality of the spectrum data, the biogas slurry is filtered by three stages in the application, the first stage is the filter screen (1) attached to the outlet of the anaerobic fermentation tank (0), the second stage is the T-shaped three-way filter (2) between the peristaltic pump (301) and the cross pipe (302), and the third stage is the Y-shaped filter (6) between the biogas slurry temporary storage bottle (5) and the check valve (810).

[0025] After the host computer (9) receives the information that the spectrum data can be collected, the micro spectrometer (11) starts to collect the spectrum data of the biogas slurry in the cuvette (102) through the halogen light source (12) and the standard SMA905 optical fiber (803, 808) compared with the cuvette and support (10). After the near-infrared transmission spectrum data of the biogas slurry is collected, the STM32 microcontroller (7) sends the instruction of "discharging biogas slurry" and starts timing. After receiving the instruction, the STM32 microcontroller (7) starts the peristaltic pump (304, 801) in reverse, opens the electromagnetic valve (303, 305, 802) and delays for 35 seconds, sends the biogas slurry in the buffer bottle (804, 805) and the liquid pipeline to the biogas slurry temporary storage bottle (5), and sends the information of "discharging biogas slurry" to the STM32 microcontroller (4). After receiving the information, the STM32 microcontroller (4) starts the peristaltic pump (308) in reverse, opens the electromagnetic valve (306, 307), and discharges the biogas slurry in the biogas slurry temporary storage bottle (5) and the small particle material in the T-shaped three-pass filter (2) to the anaerobic fermentation tank (0). In order to ensure that the pipeline and the biogas slurry in the biogas slurry temporary storage bottle (5) can be completely discharged, the process starts all the corresponding devices and delays for 2 minutes.

[0026] After the biogas slurry is discharged, the peristaltic pump (308) is stopped, the electromagnetic valve (306, 307) is closed, and the system enters standby state. At this point, the biogas slurry filtering, sample injection, spectrum collection, sample discharge, and filter flushing process is completed, and the near-infrared transmission spectrum data of the anaerobic fermentation biogas slurry is obtained. Wait for the next instruction of the host computer (9) to perform the next data collection.

[0027] The preferred embodiments are disclosed in the present embodiment, and are not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application, and the specific protection scope shall be subject to the definition of the claims.

[0028] In addition, it should be understood that the present specification is described in terms of embodiments, and each embodiment does not contain only one independent technical solution. The description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the present embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An online acquisition device for near-infrared transmission spectrum data of anaerobic fermentation biogas slurry, characterized in that, The application relates to a back-flushing anti-blocking biogas slurry filtering system and an online liquid-phase near-infrared spectrum acquisition system. The back-flushing anti-blocking biogas slurry filtering system is used for realizing effective filtration of solid particles in biogas slurry and avoiding the influence of solid particles on the stability of collected data in a transmission spectrum data acquisition process; the back-flushing anti-blocking biogas slurry filtering system comprises a primary filter screen (1), a T-shaped three-pass filter (2), filtering system peripherals (3), an STM32 microcontroller (4) and a biogas slurry temporary storage bottle (5); wherein the filtering system peripherals (3) comprise a cross variable-diameter pipeline (302), peristaltic pumps (301, 304 and 308), electromagnetic valves (303, 305, 306 and 307), a liquid level sensor (309) and a communication line (310). The online liquid-phase near-infrared spectrum acquisition system is used for realizing stable acquisition of flow liquid-phase transmission spectrum data and avoiding the influence of cavitation problems on the consistency of spectrum data acquisition. The online liquid-phase near-infrared spectrum acquisition system comprises a Y-shaped filter (6), an STM32 microcontroller (7), spectrum data online acquisition peripherals (8), an upper computer (9), a cuvette and a support (10), a miniature spectrometer (11) and a high-power halogen light source (12); wherein the spectrum data online acquisition peripherals (8) comprise peristaltic pumps (801 and 812), electromagnetic valves (802, 811 and 813), standard SMA905 optical fibers (803 and 808), double-buffered bottles (804 and 805), liquid level sensors (806 and 807), USB data lines (809 and 814) and a check valve (810).

2. An online acquisition device for near-infrared transmission spectrum data of anaerobic fermentation biogas slurry, characterized in that, A three-stage filtering mechanism is constructed to ensure effective removal of solid particles in biogas slurry. The three-stage filtering mechanism is characterized in that the first stage is the filter screen (1) attached to the flow outlet of an anaerobic fermentation tank (0) and used for preliminarily removing large-particle solid impurities; the second stage is the T-shaped three-pass filter (2) between the peristaltic pump (301) and the cross pipeline (302), and the "upper inlet and upper outlet, upper inlet and lower discharge" structure can realize efficient biogas slurry filtration and back-flushing anti-blocking; and the third stage is the Y-shaped filter (6) between the biogas slurry temporary storage bottle (5) and the check valve (810) and used for ensuring effective removal of solid particles in the biogas slurry entering the cuvette.

3. The device according to claim 1, wherein, The back-flushing anti-blocking biogas slurry filtering system fully utilizes the synergistic effect of fluid dynamics and gravity to realize reverse flushing self-cleaning maintenance of the screen of the T-shaped three-pass filter (2), and the specific process comprises the following steps: S1: when normal sampling filtration is carried out, the biogas slurry enters horizontally from the left flow inlet of the T-shaped three-pass filter (2), penetrates vertically through the built-in filter screen and then flows out stably from the right flow outlet, so that solid particles are prevented from excessively accumulating on the screen surface; S2: when sampling discharge is carried out, the biogas slurry is reversely filled from the flow outlet under high pressure, rapidly fills the filter cavity and forms a downward vortex, drives the retained particles to be flushed and discharged from the bottom discharge outlet along the gravity direction, completely removes the clogging materials in the screen holes and realizes self-cleaning maintenance.

4. The device according to claim 1, wherein, The online liquid-phase near-infrared spectrum acquisition system adopts a double-buffered bottle structure and PID liquid level closed-loop control, so that the pipeline cavitation risk in the transportation of high-viscosity biogas slurry is effectively reduced. The double-buffer bottle structure uses the series capacity gradient design of the upper buffer bottle (transition chamber) and the lower buffer bottle (stable chamber), adopts an STM32 microcontroller (7) as a core control unit, constructs a second-order transfer function model of the double-buffer bottle sample feeding system based on the material balance principle, considers the variable-diameter pipeline liquid resistance, the upper / lower buffer bottle capacity coefficient and the transmission time delay, quantifies the capacity lag to simulate the flow state of the biogas slurry, and realizes the PID liquid level closed-loop control. The PID liquid level closed-loop control realizes the liquid level closed-loop control of the double-buffer bottle through the real-time monitoring of the liquid level by the liquid level sensors (806, 807), adjusts the peristaltic pump speed in combination with the PWM controller and the PID control algorithm, effectively absorbs the instantaneous flow impact, prevents the negative pressure from being exhausted, blocks the bubbles from entering the cuvette (1002), realizes the dynamic matching of the pump speed and the liquid resistance, ensures the continuous full-liquid stable operation of the system, and avoids the bubbles from affecting the stability and repeatability of the transmission spectrum data acquisition.

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