A testing device and method for determining the ammonia content in fly ash

Abstract

The application discloses a testing device and method for determining the ammonia content in fly ash, which comprises a device host and a disposable detection disc. The disposable detection disc is designed in a modular manner and comprises a sample cavity, an annular detection cavity, a hydrophobic and air-permeable membrane and a pressure balance capsule. The sample cavity is used for containing fly ash samples and pre-set alkaline reagents; the annular detection cavity is a closed gas chamber, the inner side wall of which is integrated with a gas-sensitive membrane, and the annular detection cavity supports dual-mode detection of optics and electricity; the hydrophobic and air-permeable membrane separates the sample cavity and the detection cavity and only allows gas to permeate; and the pressure balance capsule is made of a flexible material and is used for maintaining the stable pressure in the detection cavity. The physical isolation of the sensor and the pollution source, the efficient extraction and uniform detection of gas, the strong anti-interference capability and the one-key operation are realized, and the device has the advantages of rapidness, accuracy, reliability and convenience, and perfectly meets the rapid detection requirements of construction sites.

Description

Technical Field

[0001] This invention relates to the field of fly ash detection technology, and in particular to a testing device and method for determining the ammonia content in fly ash. Background Technology

[0002] Currently, the standard methods for determining the ammonia content in fly ash are mainly based on laboratory distillation titration or spectrophotometry. While these methods are highly accurate, they have inherent drawbacks such as cumbersome procedures, long processing times (usually several hours), and reliance on large equipment and skilled personnel. They are completely unable to meet the requirements for rapid determination in on-site environments such as mixing plants and precast component factories.

[0003] To meet the needs of on-site testing, some attempts have been made to improve existing technologies towards automation and portability. For example, Chinese invention patent CN111751362A discloses a device and method for detecting ammonia content in fly ash, which uses a gas pump to blow out the ammonia gas generated by the reaction and guide it to a gas-sensitive sensor for detection. Compared with traditional laboratory methods, this approach is faster. However, existing improved solutions, including CN111751362A, still face a series of insurmountable technical bottlenecks when applied to the special matrix of fly ash.

[0004] Sensors are susceptible to contamination and poisoning, and pipelines are contaminated: As shown in the scheme of CN111751362A, the gas produced by the reaction needs to be transported through a gas pump and pipelines. During this process, the moisture, alkaline droplets and fine dust that may be carried by the fly ash reaction liquid will directly contact and contaminate the gas pump, pipelines and the final gas sensor sensing element, resulting in decreased sensor sensitivity, response drift or even permanent damage, short equipment life and high maintenance costs.

[0005] Low gas mass transfer efficiency and adsorption residue: Ammonia is extracted by purging with a gas pump. The gas mixes with the liquid in an open or semi-open chamber. The extraction efficiency is unstable and affected by factors such as airflow and liquid level. Furthermore, ammonia molecules are easily adsorbed on the long transmission pipeline and inner wall, which not only reduces the detection sensitivity but also causes a serious "memory effect." That is, the residue of the previous high-concentration sample will interfere with the detection results of the next low-concentration sample. The cleaning process is complex and the effect is difficult to guarantee.

[0006] Poor anti-interference capability and low system integration: The gas sensors in such devices are usually single-mode (such as electrochemical or metal oxide semiconductor type only). Under complex temperature and humidity changes and possible cross-gas interference (such as VOCs), the measurement results are prone to drift, and the accuracy is difficult to guarantee. At the same time, it is challenging to effectively integrate multiple modules such as reaction, gas separation, transmission, and detection into a portable device. The device is often still too large or lacks reliability.

[0007] Limited automation and inconvenient operation: Existing solutions usually still require manual pretreatment steps such as weighing fly ash and adding liquid, which cannot achieve true one-click fully automatic detection of "sample in - result out". There are many operation steps, which require personnel skills and cannot completely avoid human error.

[0008] In summary, even existing technologies (such as CN111751362A) have failed to effectively solve the core challenges in on-site ammonia content detection of fly ash, including sensor protection (contamination / poisoning), efficient and non-destructive gas transmission and anti-clogging, and anti-interference in complex on-site environments. Therefore, there is an urgent need in this field for a technical solution that can achieve physical isolation between the sensor and the sample, achieve efficient gas extraction and mixing without external gas paths, and possess an inherent anti-interference calibration mechanism, in order to fundamentally overcome the aforementioned deficiencies and achieve truly fast, accurate, reliable, and convenient on-site detection. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing a testing device and method for determining the ammonia content in fly ash.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a testing device for determining the ammonia content in fly ash, comprising:

[0011] The main unit of the device is equipped with a control unit, an optical detection module, an electrical detection module, a centrifugal drive unit, and a pneumatic pressure regulation unit.

[0012] A disposable test disc is detachably mounted on the disc platform of the main unit of the device and is driven to rotate by the centrifugal drive unit.

[0013] The disposable testing disc has a sample chamber inside, which is used to hold fly ash samples and reagents.

[0014] The annular detection cavity is a closed gas chamber with a gas-sensitive membrane integrated on its inner wall. Microelectrodes are fabricated on the gas-sensitive membrane. The microelectrodes are connected to electrical contacts located on the edge of the disc. The electrical contacts are electrically connected to the electrical detection module of the main unit of the device. The area on the surface of the annular detection cavity corresponding to the gas-sensitive membrane is an optically transparent window, which corresponds to the optical path of the optical detection module of the main unit of the device.

[0015] A hydrophobic and breathable membrane is disposed between the sample chamber and the annular detection chamber to isolate the two while allowing gas to pass through;

[0016] A pressure balancing bladder is disposed within the disposable detection disc. The pressure balancing bladder is made of a flexible material, and its internal space is connected to the gas space of the annular detection chamber. It is used to expand when gas enters to maintain the stability of the internal pressure of the annular detection chamber.

[0017] Preferably, the pressure balancing bladder is a flexible thin film bladder that can be passively expanded and contracted, and its initial state is a compressed or folded state.

[0018] Preferably, the air pressure regulating unit is an active circulating homogenization system;

[0019] The active circulating homogenization system includes: at least one movable magnetic plate disposed in the storage ring cavity of a disposable test disc, the pressure balancing bladder being fixed to the movable magnetic plate; an electromagnetic drive unit disposed on the main unit of the device corresponding to the position of the movable magnetic plate; the control unit drives the movable magnetic plate to move by controlling the magnetic force generated by the electromagnetic drive unit, thereby actively compressing or releasing the pressure balancing bladder.

[0020] Preferably, a partition and a block-shaped gas-sensitive membrane are symmetrically arranged inside the annular detection cavity. The partition and the gas-sensitive membrane divide the annular detection cavity into two connected, semi-circular sub-detection cavities. Each sub-detection cavity is provided with an independent pressure balancing bladder. Each pressure balancing bladder is fixed to an independent movable magnetic plate and corresponds to an electromagnetic drive component.

[0021] The control unit is configured to control the two electromagnetic drive components to work alternately, apply force to the two movable magnetic plates, and cause the two pressure balance bladders to be compressed or released alternately, thereby generating a reciprocating oscillating airflow between the two semi-circular sub-detection cavities, forcing the gas to repeatedly pass through the gas-sensitive membrane.

[0022] Preferably, the gas-sensitive membrane is a nanomaterial membrane that specifically responds to ammonia. The optical detection module generates an optical signal by detecting changes in the optical properties of the gas-sensitive membrane before and after ammonia adsorption, and the electrical detection module generates an electrical signal by detecting changes in the electrical parameters of the gas-sensitive membrane before and after ammonia adsorption. The control unit is configured to receive the optical signal and the electrical signal, and calculate the ammonia content in the fly ash based on a signal fusion algorithm.

[0023] Preferably, the main unit of the device further includes an ambient temperature and pressure sensor for detecting ambient temperature and air pressure, and the control unit is configured to compensate and correct the detection results based on the data from the ambient temperature and pressure sensor.

[0024] A method for determining the ammonia content in fly ash using the above-mentioned testing device includes the following steps:

[0025] S1. Sample loading: Install the pre-loaded disposable test discs onto the main unit's disc carrier.

[0026] S2, Centrifugal reaction and gas extraction: Control the centrifugal drive unit to drive the disc to rotate, so that the fly ash and reagent in the sample chamber mix and react to release ammonia gas. The ammonia gas diffuses to the annular detection chamber through the hydrophobic and gas-permeable membrane, and the pressure balance bladder expands to maintain pressure stability.

[0027] S3. Detection: After centrifugation stops, perform static detection and / or dynamic cyclic detection (start the air pressure regulation unit to generate reciprocating oscillating airflow) and simultaneously acquire optical and electrical signals;

[0028] S4. Signal Processing and Output: The control unit processes and fuses the signals, calculates and outputs the ammonia content result.

[0029] The present invention has the following beneficial effects:

[0030] 1. This invention creatively isolates the sample reaction chamber and the detection chamber through a hydrophobic and breathable membrane, and utilizes high-speed centrifugal force to completely separate and settle fly ash solid particles. This design ensures that only gas molecules can diffuse through the breathable membrane into the closed annular detection chamber, while liquids carrying corrosive ions, alkaline droplets, and dust are completely blocked. This completely prevents the precision optical window and integrated gas-sensitive membrane from contacting the complex sample matrix, fundamentally solving the core problems of sensor poisoning, damage, and microchannel blockage, and greatly improving the reliability and service life of the device.

[0031] 2. This invention does not rely on slow natural diffusion or external air pump purging, but utilizes centrifugal force as the active driving force. While accelerating solid-liquid separation, the resulting dynamic pressure significantly promotes the transmembrane mass transfer efficiency of ammonia. Furthermore, an electromagnetic drive controls a magnetic plate to alternately compress the pressure balance bladders in different sub-detection chambers, generating a controlled reciprocating oscillating airflow within a closed annular cavity. This airflow forces the gas to repeatedly penetrate the gas-sensitive membrane, achieving forced convection and mixing, eliminating detection blind zones, and enabling the sensor to obtain a sufficient and uniform response within seconds. This results in highly sensitive and rapid detection of low-concentration ammonia.

[0032] 3. This invention integrates a gas-sensitive membrane capable of simultaneously outputting optical and electrical signals at the same location within the annular detection cavity. The optical signal is insensitive to humidity and exhibits good stability, while the electrical signal is prone to drift but has a sensitive response. By comparing and fusing the dual-mode signals in real time, the system can use the optical signal as an intrinsic parameter to intelligently compensate for the drift of the electrical signal. Simultaneously, the introduction of a flexible pressure balancing bladder dynamically maintains the stability of the pressure within the detection cavity, eliminating measurement errors caused by pressure fluctuations. This combined mechanism effectively overcomes interference from complex on-site environments (temperature and humidity changes, cross-contamination of gases), resulting in stable and reliable output results.

[0033] 4. This invention combines the precise pre-packaging of alkaline reagents with the standardized quantitative sampling process for fly ash samples through a modular and standardized disposable testing disc design. This simplifies the weighing operation, which originally required a precision balance and specialized skills, to rapid sample loading using a matching quantitative sampler (such as a standard volumetric scoop). User operation is simplified to four steps: "quantitative sampling, loading the disc, inserting the main unit, and one-button start," eliminating the need for a balance or complex operations and greatly reducing errors caused by inaccurate weighing and improper operation. After testing, all waste liquid and residue are completely sealed within the disc and discarded along with it. This design achieves extremely high operational convenience and result consistency, and physically eliminates cross-contamination between samples, perfectly meeting the needs of construction sites for efficient, hygienic, and environmentally friendly rapid testing. Attached Figure Description

[0034] Figure 1 This is a three-dimensional structural diagram of the testing device proposed in this invention;

[0035] Figure 2 This is a schematic diagram of the exploded structure of the disposable detection disc proposed in this invention;

[0036] Figure 3 This is a schematic diagram of the split cross-sectional structure of the disposable detection disc proposed in this invention;

[0037] Figure 4 This is a top-section schematic diagram of the third disk proposed in this invention;

[0038] Figure 5 This is a top-sectional view of the main unit of the device proposed in this invention;

[0039] Figure 6 This is a partial side sectional view of the main unit of the device proposed in this invention;

[0040] Figure 7 for Figure 6 Enlarged schematic diagram of the structure at point A in the diagram.

[0041] In the diagram: 1. Main unit, 2. Optical detection module, 3. Electrical detection module, 4. Centrifugal drive unit, 5. Disposable detection disc, 6. Disc stage, 7. Sample chamber, 8. Annular detection chamber, 9. Gas-sensitive membrane, 10. Microelectrode, 11. Hydrophobic and breathable membrane, 12. Pressure balance bladder, 13. Magnetic plate, 14. Electromagnetic drive component, 15. Partition, 16. First disc, 17. Second disc, 18. Third disc, 19. Top cover, 20. Locking mechanism, 21. Electric telescopic rod, 22. Feeding channel. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0043] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0044] Example 1

[0045] Reference Figure 1 A testing device for determining the ammonia content in fly ash, comprising:

[0046] The main unit 1 of the device is equipped with a control unit, an optical detection module 2, an electrical detection module 3, a centrifugal drive unit 4 and a pneumatic pressure regulating unit. A pull-out tray is slidably installed on the front side of the main unit 1, and a disc stage 6 is rotatably installed on the tray. The centrifugal drive unit 4 is fixedly installed in the tray and drives the disc stage 6 to rotate.

[0047] The disposable test disc 5 is detachably mounted on the disc stage 6 of the main unit 1 and is driven to rotate by the centrifugal drive unit 4.

[0048] The disposable test disc 5 has a sample chamber 7 inside, which is used to hold fly ash samples and reagents;

[0049] The annular detection cavity 8 is a closed gas chamber with a gas-sensitive membrane 9 integrated on its inner wall. Microelectrodes 10 are fabricated on the gas-sensitive membrane 9. The microelectrodes 10 are connected to electrical contacts located on the edge of the disc. The electrical contacts are electrically connected to the electrical detection module 3 of the device host 1. The area on the surface of the annular detection cavity 8 corresponding to the gas-sensitive membrane 9 is an optically transparent window, which corresponds to the optical path of the optical detection module 2 of the device host 1.

[0050] A hydrophobic and breathable membrane 11 is disposed between the sample chamber 7 and the annular detection chamber 8 to isolate the two while allowing gas to pass through.

[0051] The pressure balancing capsule 12, housed within the disposable detection disc 5, is made of flexible material. It is a passively expandable and contractible flexible film capsule, initially in a compressed or folded state. Its internal space is connected to the gas space of the annular detection chamber 8, and it expands upon gas entry to maintain stable pressure within the chamber. It should be noted that its working principle is based on a passive pressure compensation mechanism according to the ideal gas law (PV=nRT): when ammonia diffuses into the annular detection chamber 8 (n increases), the internal pressure (P) tends to increase. At this time, the flexible pressure balancing capsule 12 automatically expands under the pressure difference, increasing the total volume (V) of the chamber, thereby dynamically offsetting and maintaining a relatively constant internal pressure (P). This provides a stable and reliable low-pressure environment for subsequent optical and electrical detection, effectively avoiding sensor signal drift caused by pressure fluctuations and ensuring the accuracy of quantitative detection.

[0052] Specifically, such as Figure 5 As shown, the main unit 1 of the device is equipped with a locking mechanism 20, which locks the tray in place. Figure 7 As shown, an electric telescopic rod 21 is fixedly installed inside the main unit 1 of the device. The optical detection module 2 and the electrical detection module 3 are both fixedly connected to the telescopic rod 21. The stopping angle of the disposable detection disc 5 is controlled by the centrifugal drive unit 4. At this angle, when the electric telescopic rod 21 extends, the electrodes of the electrical detection module 3 make contact with the electrical contacts of the microelectrode 10, thus conducting electricity, and the detection end of the optical detection module 2 is aligned with the optical transparent window. The coordinated design of the electric telescopic rod 21 and the locking mechanism 20 ensures the repeatability and reliability of the optical alignment and electrical connection between the main unit and the disc during each test. It is a key mechanical structure for achieving "plug and play" and high-precision detection.

[0053] like Figure 2 , Figure 3As shown, the disposable testing disc 5 has a multi-layer structure, consisting of a first disc 16, a second disc 17, a third disc 18, and a top cover 19 from bottom to top. The disposable testing disc 5 is made of a transparent polymer material (such as PMMA or COC). The discs are bonded together by hot pressing to form a circular disc body. The bottom of the first disc 16 is provided with a bayonet that mates with the drive shaft of the disc stage 6. The sample chamber 7 is located inside the first disc 16. The hydrophobic and breathable membrane 11 is fixedly installed on the second disc 17. The annular testing chamber 8 is located inside the third disc 18. The third disc 18 also has a storage annular cavity that communicates with the outside world for placing the pressure balancing bladder 12. The upper surface of the third disc 18 has a feeding channel 22 that passes through the second disc 17 and communicates with the sample chamber 7. The top cover 19 is tightly fitted to the upper opening of the feeding channel 22.

[0054] In this embodiment, the air pressure regulating unit is an active circulating homogenization system;

[0055] The active circulating homogenization system includes: at least one movable magnetic plate 13 disposed within the storage ring cavity of the disposable test disc 5, with a pressure balancing bladder 12 fixed to the movable magnetic plate 13; and an electromagnetic drive component 14 disposed on the main unit 1 corresponding to the position of the movable magnetic plate 13 (see Figure 5 );

[0056] The control unit drives the movable magnetic plate 13 to move by controlling the magnetic force generated by the electromagnetic drive 14, thereby actively compressing or releasing the pressure balance bladder 12. This system provides active control capabilities that go beyond passive compensation. By controlling the electromagnetic drive 14 through a program, the instantaneous pressure in the annular detection chamber 8 can be precisely adjusted. This not only assists in the initial gas mixing but can also be used in the future to realize more advanced detection modes, such as pulse injection detection, providing a hardware foundation for methodological expansion.

[0057] The sample chamber 7 of the disposable test disc 5 is pre-filled with a quantitative amount of alkaline reaction reagent. The alkaline reaction reagent is pre-quantitatively packaged into the sample chamber 7 of each disposable disc in a factory-scale, high-precision industrial production environment. The fly ash sample is quantitatively sampled and added to the sample chamber 7 through the feeding channel 22. This design moves the "reagent weighing" step, which is most prone to introducing errors, to the front end and ensures its accuracy through industrial production. It simplifies the on-site operation to "quantitative sampling", greatly reducing human error and is an important prerequisite for achieving "one-click" operation and high repeatability.

[0058] The gas-sensitive membrane 9 is a nanomaterial membrane with a specific response to ammonia, preferably polyaniline. The optical detection module 2 generates an optical signal by detecting changes in the optical properties of the gas-sensitive membrane 9 before and after ammonia adsorption. The electrical detection module 3 generates an electrical signal by detecting changes in the electrical parameters of the gas-sensitive membrane 9 before and after ammonia adsorption. The control unit is configured to receive both the optical and electrical signals and calculate the ammonia content in the fly ash based on a signal fusion algorithm. The core advantage of dual-mode detection lies in the mutual verification and compensation between the signals. For example, optical signals (such as changes in reflectivity) are less sensitive to humidity but may have a slower response, while electrical signals (such as changes in resistance) respond quickly but are easily affected by ambient temperature and humidity drift. The control unit performs cross-analysis and compensation of the two signals through a fusion algorithm, effectively eliminating interference and significantly improving the accuracy and reliability of detection results in complex field environments.

[0059] The main unit 1 also includes an ambient temperature and pressure sensor for detecting ambient temperature and air pressure. The control unit is configured to compensate and correct the detection results based on the data from the ambient temperature and pressure sensor, which provides the environmental parameters during detection. Using this data, the control unit can perform real-time corrections to calculations related to gas laws and provide compensation for drift in electrical sensors, making it an indispensable part of achieving intelligence and high precision.

[0060] Example 2

[0061] Reference Figure 4 Unlike Embodiment 1, a partition 15 and a block-shaped gas-sensitive membrane 9 are symmetrically arranged inside the annular detection cavity 8. The partition 15 and the gas-sensitive membrane 9 divide the annular detection cavity 8 into two connected, semi-circular sub-detection cavities. There are two pressure balancing bladders 12, which are connected to the two sub-detection cavities respectively. Each pressure balancing bladder 12 is fixed on an independent movable magnetic plate 13 and corresponds to an electromagnetic drive component 14.

[0062] In this embodiment, the control unit is configured to control the two electromagnetic drive units 14 to work alternately, apply force to the two movable magnetic plates 13, and cause the two pressure balance bladders 12 to be alternately compressed or released, thereby generating a reciprocating oscillating airflow between the two semi-circular sub-detection cavities, forcing the gas to repeatedly pass through the gas-sensitive membrane 9.

[0063] It should be noted that the reference Figure 3 , Figure 4 After the centrifugal drive unit 4 stops rotating, the control unit activates the air pressure regulation unit. By precisely controlling the direction and magnitude of the current applied to the two electromagnetic drive components 14, it generates alternating adsorption and repulsion forces on the two movable magnetic plates 13. This drives the two pressure balance bladders 12 to perform alternating compression and expansion phase difference actions.

[0064] This action creates a periodic pressure difference between the two connected semi-circular sub-detection chambers, driving the gas to repeatedly pass through the gas-sensitive membrane 9, which serves as the channel between the chambers, thus forming a strong reciprocating oscillating airflow. Its functions are: 1) to achieve active mixing through forced convection, overcoming the uneven gas concentration within the chambers caused by static diffusion and ensuring consistent response throughout the gas-sensitive membrane 9; 2) to improve response speed and detection sensitivity by enhancing the contact frequency and efficiency between the gas and the sensitive material; and 3) to effectively mitigate the memory effect through the scouring effect of the airflow on the membrane surface. The result is a leap from "static sampling detection" to "dynamic process detection," significantly improving detection performance.

[0065] Example 3

[0066] This embodiment provides a test method for determining the ammonia content in fly ash using the test device described in Embodiment 1 or Embodiment 2, including the following steps:

[0067] S1. Sample loading: Install the disposable test disc 5 containing the fly ash sample to be tested onto the disc platform 6 of the main unit 1 of the device.

[0068] S2, Centrifugal reaction and gas extraction: Control the centrifugal drive unit 4 to drive the disposable detection disc 5 to rotate. Under the action of centrifugal force, the fly ash in the sample chamber 7 reacts with the reagent to release ammonia gas. The ammonia gas diffuses to the annular detection chamber 8 through the hydrophobic and breathable membrane 11. The pressure balance bladder 12 expands to maintain the pressure stability inside the chamber.

[0069] S3. Detection: After centrifugation stops, perform one or two of the following detection modes:

[0070] Mode 1: Static detection. Under the condition that the annular detection cavity 8 is closed and static, the optical detection module 2 and the electrical detection module 3 are started simultaneously to acquire optical signals and electrical signals respectively.

[0071] Mode 2: Dynamic cyclic detection. The air pressure regulation unit is activated to generate reciprocating oscillating airflow between the sub-detection chambers of the annular detection chamber 8. At the same time, the optical detection module 2 and the electrical detection module 3 monitor the signal changes in real time. Mode 2 can capture the entire process of dynamic interaction between gas and sensitive membrane. Its signal curve contains richer feature information. By analyzing parameters such as response rate and peak value through algorithms, the anti-interference ability and quantitative accuracy can be further enhanced.

[0072] S4. Signal Processing and Output: The control unit processes and fuses optical and electrical signals, calculates and outputs the ammonia content detection results; the control unit receives optical signal O and electrical signal E, and reads temperature T and air pressure P data collected by the ambient temperature and pressure sensor. Based on the signal fusion algorithm and compensation correction model, the ammonia content value in fly ash is calculated.

[0073] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A test device for determining the ammonia content in fly ash, characterized in that The application relates to a device for detecting ammonia in fly ash, which comprises the following parts: a device host internally provided with a control unit, an optical detection module, an electrical detection module, a centrifugal driving unit and a gas pressure regulating unit; a disposable detection disc detachably mounted on a disc loading platform of the device host and driven to rotate by the centrifugal driving unit; a disc body of the disposable detection disc is internally provided with a sample cavity for containing fly ash samples and reagents; a ring-shaped detection cavity is a closed gas chamber, the inner side wall of the ring-shaped detection cavity is integrated with a gas-sensitive membrane, the gas-sensitive membrane is provided with microelectrodes, the microelectrodes are connected with electrical contacts arranged at the edge of the disc, the electrical contacts are electrically connected with the electrical detection module of the device host, the surface of the ring-shaped detection cavity corresponding to the area of the gas-sensitive membrane is an optically transparent window corresponding to the light path of the optical detection module of the device host; a hydrophobic and air-permeable membrane is arranged between the sample cavity and the ring-shaped detection cavity and is used for isolating the two and allowing gas to permeate; a pressure balance bag is arranged in the disposable detection disc, the pressure balance bag is made of flexible material, the internal space of the pressure balance bag is in communication with the gas space of the ring-shaped detection cavity, and the pressure balance bag is used for expanding to maintain the stability of the internal pressure of the ring-shaped detection cavity when gas enters.

2. The test device for determining the ammonia content in fly ash according to claim 1, characterized in that: The pressure balance bag is a flexible film bag body which can be passively expanded and contracted, and the initial state of the pressure balance bag is a compressed or folded state.

3. The test device for determining the ammonia content in fly ash according to claim 1, characterized in that: The gas pressure regulating unit is an active circulating homogenization system; the active circulating homogenization system comprises at least one movable magnetic plate arranged in the disposable detection disc, and the pressure balance bag is fixed on the movable magnetic plate; electromagnetic driving members corresponding to the positions of the movable magnetic plates are arranged on the device host, and the control unit drives the movable magnetic plates to move by controlling the magnetic force generated by the electromagnetic driving members, so that the pressure balance bag is actively compressed or released.

4. The test device for determining the ammonia content in fly ash according to claim 3, characterized in that: The ring-shaped detection cavity is symmetrically provided with a partition plate and a block-shaped gas-sensitive membrane, and the partition plate and the gas-sensitive membrane divide the ring-shaped detection cavity into two communicating semicircular arc-shaped sub-detection cavities; there are two pressure balance bags, and the two pressure balance bags are respectively in communication with the two sub-detection cavities, each pressure balance bag is fixed on an independent movable magnetic plate, and corresponds to an electromagnetic driving member.

5. The test device for determining the ammonia content in fly ash according to claim 4, characterized in that: The control unit is configured to control the two electromagnetic driving members to work alternately, apply force to the two movable magnetic plates, and make the two pressure balance bags be alternately compressed or released, so that reciprocating oscillation gas flow is generated between the two semicircular arc-shaped sub-detection cavities, and the gas is forced to repeatedly pass through the gas-sensitive membrane.

6. The test device for determining the ammonia content in fly ash according to claim 1, characterized in that: The gas-sensitive membrane is a nano material membrane which has specific response to ammonia, the optical detection module generates an optical signal by detecting the change of the optical characteristics of the gas-sensitive membrane before and after ammonia is adsorbed, and the electrical detection module generates an electrical signal by detecting the change of the electrical parameters of the gas-sensitive membrane before and after ammonia is adsorbed.

7. The test device for determining the ammonia content in fly ash according to claim 6, characterized in that: The control unit is configured to receive the optical signal and the electrical signal and calculate the ammonia content value in fly ash based on a signal fusion algorithm.

8. The test device for determining the ammonia content in fly ash according to claim 1, characterized in that: The device host further comprises an ambient temperature and pressure sensor for detecting ambient temperature and air pressure, and the control unit is configured to compensate and correct the detection result based on the data of the ambient temperature and pressure sensor.

9. The test device for determining the ammonia content in fly ash according to claim 1, characterized in that: A quantitative alkaline reaction reagent is pre-set in the sample cavity of the disposable detection disc.

10. A test method for determining the ammonia content of fly ash, characterized by: The test device for determining the ammonia content in fly ash is used to test the ammonia content in fly ash according to any one of claims 1-9.

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