A graphite sulfur detection device for gaskets

Abstract

This invention relates to the field of graphite material testing equipment, and discloses a sulfur content detection device for graphite used in sealing gaskets. The device includes a tubular furnace and a main testing unit. The tubular furnace has a preheating zone and a central constant temperature zone. A sample injection drive motor moves the discharge tube internally. The main testing unit integrates a gas mass flow controller, an electrolytic cell, and a microcontroller. The microcontroller acquires the titration potential signal and performs differentiation. Combined with a flow modulation threshold and a limit yield threshold, the sample injection drive motor and the gas mass flow controller are controlled. When the first derivative of the potential reaches the limit yield threshold, the motor is controlled to pull the discharge tube back towards the preheating zone. The feedforward potential offset is calculated by extracting the carrier gas flow rate change rate and displacement acceleration. The net potential signal is obtained by subtracting the feedforward potential offset from the measured signal. By preventing incomplete gas absorption and eliminating physical interference caused by gas path adjustment, the detection accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of graphite material testing equipment, specifically to a device for detecting the sulfur content of graphite in sealing gaskets. Background Technology

[0002] Sealing gaskets are typically made of flexible graphite, and their sulfur content is a critical quality indicator. Excessive sulfur can cause corrosion of metal flanges and pipelines in high-temperature, high-pressure environments. Currently, the sulfur content of graphite is commonly determined using a tubular furnace combustion method combined with coulometric titration. During operation, a quartz boat containing the graphite sample is pushed into a high-temperature tubular furnace for combustion. The generated sulfur dioxide gas is carried by a carrier gas into the electrolytic cell of the detection unit for titration. The final sulfur content is calculated based on the amount of electricity consumed in the electrolysis.

[0003] However, existing technologies have shortcomings in practical applications. In constant-rate injection mode, when graphite samples enter the high-temperature isothermal zone of the tube furnace, they often undergo violent combustion, releasing a large amount of sulfur dioxide gas in a very short time. This high concentration of gas can easily exceed the processing capacity of the absorbent in the electrolytic cell, causing some gas to be discharged directly without being completely absorbed, resulting in a lower final detection result. To address this rapid combustion phenomenon, some existing devices attempt to slow down the gas generation rate by dynamically adjusting the carrier gas flow rate or temporarily pulling the quartz boat backward.

[0004] However, the rapid retraction of the sample introduction structure and the instantaneous change in gas flow rate can trigger severe pressure fluctuations and backflow in the closed pipeline system. These drastic pressure changes directly disrupt the stability of the liquid level within the electrolytic cell, causing a physical potential shift in the indicating electrode that is unrelated to the chemical reaction concentration. Existing systems cannot separate this physical interference caused by mechanical action from the actual chemical titration potential, leading the closed-loop control system to receive incorrect feedback signals and output incorrect electrolytic current, ultimately resulting in deviations in the sulfur content determination results. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a graphite sulfur content detection device for sealing gaskets. This device solves the problems of incomplete absorption in the electrolytic cell when the sample is rapidly combusted and releases a large amount of sulfur dioxide, and the potential for pressure fluctuations and backflow in the gas path during dynamic adjustment of the injection position and carrier gas flow rate, which in turn interfere with the accuracy of titration potential signal measurement.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a sulfur content detection device for graphite used in sealing gaskets, comprising a tubular furnace and a detection host.

[0007] The tubular furnace has a preheating zone and a central constant temperature zone. The sample inlet end of the tubular furnace is equipped with a sample inlet bracket. A sample inlet drive motor is installed on the side wall of the sample inlet bracket. The sample inlet drive motor is connected to the discharge tube. A position sensor is installed on the side of the sample inlet drive motor. The discharge tube carries a quartz boat. The sample inlet drive motor drives the discharge tube to move axially inside the tubular furnace.

[0008] The detection host integrates a gas mass flow controller, an electrolytic cell, and a microcontroller. The gas mass flow controller is connected to the gas inlet of the tubular furnace. The electrolytic cell is equipped with an indicator electrode. The gas inlet of the electrolytic cell is connected to the exhaust of the tubular furnace through a gas supply pipeline. A one-way isolation chamber is connected in series on the gas supply pipeline. A microporous glass frit is installed inside the one-way isolation chamber. The microcontroller is electrically connected to the sample injection drive motor, the position sensor, the gas mass flow controller, and the indicator electrode.

[0009] The microcontroller has preset flow modulation threshold, limit yield threshold, and phase prediction acceleration threshold, where the limit yield threshold is numerically greater than the flow modulation threshold. The microcontroller outputs control commands to the gas mass flow controller to establish a base carrier gas flow rate and controls the sample inlet drive motor to push the quartz boat into the preheating zone of the tube furnace for a preset dwell time. The microcontroller then controls the sample inlet drive motor to push the quartz boat into the central isothermal zone. The microcontroller continuously acquires the titration potential signal of the indicator electrode at a fixed sampling frequency and performs time derivative calculations on the titration potential signal to obtain the first and second derivatives of the titration potential.

[0010] When the first derivative of the titration potential is less than the flow modulation threshold and the second derivative of the titration potential is greater than or equal to the phase prediction acceleration threshold, the microcontroller outputs a flow adjustment command to the gas mass flow controller to reduce the carrier gas flow rate. When the first derivative of the titration potential is greater than or equal to the flow modulation threshold and less than the limit yield threshold, the microcontroller pauses the propulsion action of the sample injection drive motor, calculates the target carrier gas flow rate based on the base carrier gas flow rate, the preset proportional adjustment coefficient, and the difference between the first derivative of the titration potential and the flow modulation threshold, and controls the gas mass flow controller to operate according to the target carrier gas flow rate.

[0011] When the first derivative of the titration potential is greater than or equal to the limit yield threshold, the microcontroller outputs a reverse command to the injection drive motor, calculates the yield expansion critical rate based on the target carrier gas flow rate and the cross-sectional area of ​​the discharge tube, and controls the injection drive motor to pull the discharge tube back towards the preheating zone at a speed not exceeding the yield expansion critical rate. The calculation process for the yield expansion critical rate is as follows: divide the target carrier gas flow rate by the cross-sectional area of ​​the discharge tube, and then multiply by a safety margin coefficient and a dimensional conversion coefficient to obtain the yield expansion critical rate.

[0012] The microcontroller extracts the carrier gas flow rate change rate and the displacement acceleration of the injection drive motor, and inputs the carrier gas flow rate change rate and the displacement acceleration into a preset pressure-potential coupling transfer model to calculate the feedforward potential offset. The calculation process for the feedforward potential offset is as follows: the carrier gas flow rate change rate is multiplied by the flow-pressure coupling coefficient, the displacement acceleration is multiplied by the volume pressure coupling coefficient, and the products are added together to obtain the feedforward potential offset. Before being substituted into the pressure-potential coupling transfer model, the carrier gas flow rate change rate and the displacement acceleration undergo time-domain alignment matching processing based on the pneumatic transmission delay time.

[0013] The microcontroller subtracts the feedforward potential offset from the measured titration potential signal to generate a net potential signal. Based on the net potential signal, it controls the detection host to output electrolytic current in a closed loop. The total power consumption is obtained by performing time integration on the electrolytic current. The percentage of sulfur content in the graphite sample is calculated according to Faraday's law of electrolysis.

[0014] This invention provides a device for detecting the sulfur content in graphite used in sealing gaskets. It has the following advantages:

[0015] 1. This invention uses a microcontroller to acquire titration potential signals in real time and perform derivative calculations. Combined with flow modulation thresholds and phase prediction acceleration thresholds, it provides feedforward intervention to the sample injection drive motor and gas mass flow controller. When an increasing potential change trend is detected, the system automatically reduces the carrier gas flow rate or pauses the propulsion action to prevent a large amount of high-concentration sulfur dioxide gas from entering the electrolytic cell in a short period, causing incomplete absorption and improving the accuracy of sulfur content detection results.

[0016] 2. In this invention, when the first derivative of the titration potential reaches the limit of the yield threshold, the sample injection drive motor is controlled to pull the discharge tube back towards the preheating zone, rapidly reducing the combustion release rate of the graphite sample by utilizing the temperature difference. Simultaneously, the critical yield expansion rate is calculated based on the target carrier gas flow rate and the cross-sectional area of ​​the discharge tube, and the pull-back speed is limited. This avoids a sudden drop in pipeline pressure and backflow caused by the discharge tube retracting and suction, ensuring the unidirectional flow stability of the detection gas path.

[0017] 3. This invention substitutes the carrier gas flow rate change rate and displacement acceleration into the gas pressure and potential coupling transmission model to calculate the feedforward potential offset. Since changes in motor displacement and flow rate will cause gas pressure fluctuations inside the electrolytic cell and interfere with the measurement value of the indicator electrode, the system subtracts the feedforward potential offset from the measured signal to obtain the net potential signal, thus eliminating physical interference caused by mechanical action and gas path adjustment, and ensuring that the closed-loop control of the electrolysis current corresponds to the actual chemical reaction concentration. Attached Figure Description

[0018] Figure 1 This is a perspective view of the overall structure of the present invention;

[0019] Figure 2 This is a partial three-dimensional structural view of the tubular furnace and unidirectional isolation gas chamber in this invention;

[0020] Figure 3 This is a flowchart of a method for detecting sulfur content in graphite used in sealing gaskets according to an embodiment of the present invention.

[0021] Among them, 10 is a tube furnace; 11 is a sample inlet bracket; 12 is a discharge pipe; 13 is a quartz boat; 20 is a detection host; 21 is an electrolytic cell; 30 is a gas supply pipeline; 31 is a one-way isolation gas chamber; 32 is a microporous glass core; 40 is a sample inlet drive motor; and 41 is a position sensor. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See attached document Figure 1 With appendix Figure 2 The present invention provides a sulfur-containing graphite detection device for sealing gaskets, comprising: a tubular furnace 10, a detection host 20, a gas supply pipeline 30, and a sample injection drive motor 40.

[0024] The tube furnace 10 has a preheating zone and a central isothermal zone distributed along the axial direction. A sample inlet bracket 11 is provided at the sample inlet end of the tube furnace 10. A sample inlet drive motor 40 is mounted on the sample inlet bracket 11. The sample inlet drive motor 40 is connected to a discharge tube 12. A position sensor 41 is disposed on the side of the sample inlet drive motor 40. The end of the discharge tube 12 carries a quartz boat 13 containing a graphite sample and a tungsten trioxide catalyst. The sample inlet drive motor 40 drives the discharge tube 12 to move axially within the tube furnace 10.

[0025] The detection host 20 integrates an electrolytic cell 21, an indicator electrode, a microcontroller, a gas mass flow controller, and a vacuum pump. The gas mass flow controller regulates the flow rate of the carrier gas entering the tube furnace 10.

[0026] The gas pipeline 30 connects the exhaust end of the tubular furnace 10 to the gas inlet end of the electrolytic cell 21. A one-way isolation chamber 31 is connected in series on the gas pipeline 30. The one-way isolation chamber 31 is equipped with a microporous glass frit core 32. The microporous glass frit core 32 forms a physical barrier that allows gas to flow unidirectionally and blocks the backflow of liquid by means of capillary resistance.

[0027] The microcontroller establishes electrical connections with the sample injection drive motor 40, the position sensor 41, the gas mass flow controller, and the indicating electrode. The microcontroller receives the titration potential signal output from the indicating electrode. The microcontroller has preset flow modulation threshold, limit yield threshold, and phase prediction acceleration threshold. The limit yield threshold is numerically greater than the flow modulation threshold.

[0028] See attached document Figure 3 This invention provides a method for detecting sulfur content in graphite used in sealing gaskets, comprising the following steps:

[0029] S101, the microcontroller controls the central constant temperature zone of the tube furnace 10 to heat up to the set temperature, outputs control commands to the gas mass flow controller to establish the basic carrier gas flow, and controls the sample injection drive motor 40 to drive the discharge tube 12 to push the quartz boat 13 into the preheating zone of the tube furnace 10 and stay for a preset time.

[0030] S102, the feeding tube 12 pushes the quartz boat 13 into the central constant temperature zone. The microcontroller continuously collects the titration potential signal of the indicator electrode at a fixed sampling frequency, and performs time derivative calculation on the titration potential signal to obtain the first derivative and second derivative of the titration potential.

[0031] S103, when the first derivative of the titration potential is less than the flow modulation threshold and the second derivative of the titration potential is greater than or equal to the phase prediction acceleration threshold, the microcontroller outputs a flow adjustment command to the gas mass flow controller to reduce the carrier gas flow.

[0032] S104, when the first derivative of the titration potential is greater than or equal to the flow modulation threshold and less than the limit yield threshold, the microcontroller pauses the propulsion action of the sample injection drive motor 40, calculates the target carrier gas flow rate based on the basic carrier gas flow rate, the preset proportional adjustment coefficient and the difference between the first derivative of the titration potential and the flow modulation threshold, and controls the gas mass flow controller to operate according to the target carrier gas flow rate.

[0033] S105, when the first derivative of the titration potential is greater than or equal to the limit yield threshold, the microcontroller outputs a reverse command to the injection drive motor 40, calculates the yield expansion critical rate based on the target carrier gas flow rate and the cross-sectional area of ​​the discharge tube 12, and controls the injection drive motor 40 to drive the discharge tube 12 to pull back towards the preheating zone at a running speed not greater than the yield expansion critical rate.

[0034] S106, the microcontroller extracts the carrier gas flow rate change rate and the displacement acceleration of the injection drive motor 40, inputs the carrier gas flow rate change rate and displacement acceleration into the system's preset gas pressure and potential coupling transfer model to calculate the feedforward potential offset, and subtracts the feedforward potential offset from the measured titration potential signal to generate the net potential signal.

[0035] S107, the microcontroller controls the output of the detection host 20 based on the net potential signal in a closed loop, and performs time integration calculation on the electrolytic current to obtain the total power consumption. Based on Faraday's law of electrolysis, the percentage of sulfur content in the graphite sample is calculated.

[0036] See attached document Figure 3 This section details the specific implementation process of sample dehydration and system initialization in step S101. Step S101 specifically includes the following sub-steps:

[0037] S1011, mix the preset mass of graphite sample with the catalyst evenly and fill it into the quartz boat 13. The operator uses an analytical balance to weigh the graphite sample for the sealing gasket. The preset mass range is 40mg to 60mg, and can be set to 50mg. Tungsten trioxide powder is used as the catalyst. The mass ratio of tungsten trioxide powder to graphite sample is usually controlled between 2:1 and 3:1. Tungsten trioxide can act as a flux and oxidation catalyst, reducing the activation energy of graphite combustion, allowing the sulfur in graphite to be fully oxidized to generate sulfur dioxide gas at a specific temperature. The graphite sample and tungsten trioxide powder are mixed evenly in the quartz boat 13 and spread evenly at the bottom to prevent the powder from piling up too thickly, which would lead to incomplete reaction at the bottom. After filling, place the quartz boat 13 at the end of the discharge tube 12 to await sample injection.

[0038] S1012, the microcontroller controls the central isothermal zone of the tube furnace 10 to heat up to the set temperature. Specifically, the microcontroller uses an ARM-based microprocessor chip. The microcontroller internally programs a proportional-integral-derivative (PID) control algorithm. The microcontroller receives real-time temperature signals from the thermocouples inside the tube furnace 10, calculates and outputs pulse-width modulated (PWM) signals to the external heating actuators, driving the central isothermal zone of the tube furnace 10 to heat up. The set temperature range is 1000℃ to 1150℃, preferably 1050℃. This temperature range is determined based on the fact that at this temperature, with the aid of a tungsten trioxide catalyst, the graphite lattice structure can be destroyed, allowing the internally encapsulated sulfur compounds to be completely decomposed, released, and oxidized. The specific code implementation of the PID control algorithm and the temperature measurement principle of the thermocouples can be conventionally configured by those skilled in the art based on the actual hardware circuit; these are well-known technologies in the field and will not be elaborated upon here.

[0039] S1013, the microcontroller outputs control commands to the gas mass flow controller to establish a basic carrier gas flow rate. The system activates the vacuum pump inside the detection host 20. The vacuum pump provides driving negative pressure for gas delivery. The microcontroller sends a flow rate setpoint to the gas mass flow controller via its internal communication interface. The electromagnetic proportional valve inside the gas mass flow controller adjusts the valve opening according to this setpoint to stabilize the carrier gas flow rate entering the tubular furnace 10 at the basic carrier gas flow rate. The basic carrier gas flow rate ranges from 800 mL / min to 1200 mL / min, and can be specifically set to 1000 mL / min. The principle for determining the basic carrier gas flow rate is to ensure that the sulfur dioxide gas produced by the subsequent combustion reaction can be quickly delivered to the electrolytic cell 21 to reduce the physical transmission delay time, while avoiding incomplete absorption caused by gas escaping from the liquid surface of the electrolytic cell 21 due to excessive flow rate.

[0040] S1014, the microcontroller controls the sample inlet drive motor 40 to drive the discharge tube 12 to push the quartz boat 13 into the preheating zone of the tube furnace 10 and hold it there for a preset time. The microcontroller outputs a direction signal and a high-frequency pulse sequence signal to the sample inlet drive motor 40. The sample inlet drive motor 40 is a closed-loop stepper motor with a rotary encoder. The sample inlet drive motor 40 operates and drives the external linear slide mechanism to move the discharge tube 12, which is connected to the quartz boat 13, axially along the tube furnace 10 to the preheating zone of the tube furnace 10. The preheating zone is located between the sample inlet end of the tube furnace 10 and the central constant temperature zone, and the ambient temperature of the preheating zone is between room temperature and the temperature of the central constant temperature zone. The microcontroller confirms that the discharge tube 12 has reached the designated preheating position by reading the level change signal of the position sensor 41.

[0041] Upon reaching the preheating position, the sample injection drive motor 40 stops operating. The quartz boat 13 remains in the preheating zone for a preset time. The preset time ranges from 40s to 80s, and can be specifically set to 60s. The length of the preset time is determined based on the typical free water content of the graphite sample, ensuring that the moisture inside the sample can completely evaporate. During the residence period, the free water adsorbed inside the graphite sample is heated by the medium-low temperature environment, slowly evaporating into water vapor and being discharged with the carrier gas flow. By setting this physical dehydration sub-step, the instantaneous expansion and splashing of the sample caused by the instantaneous vaporization and expansion of internal moisture when the dense graphite sample directly enters the high-temperature zone is avoided, ensuring the safety of the gas path and the integrity of sulfur release.

[0042] See attached document Figure 3 This section details the specific implementation process of the isothermal zone propulsion and double-derivative signal acquisition in step S102. Step S102 specifically includes the following sub-steps:

[0043] S1021, after the preheating time is completed, the microcontroller controls the sample injection drive motor 40 to restart, driving the discharge tube 12 to push the quartz boat 13 from the preheating zone into the central isothermal zone of the tube furnace 10. During this process, the advancing speed of the sample injection drive motor 40 ranges from 5 mm / s to 15 mm / s, and can be specifically set to 10 mm / s. The determination of this advancing speed is based on ensuring that the quartz boat 13 can smoothly enter the high-temperature environment to trigger the oxidation reaction, while avoiding excessive mechanical disturbance to the airflow inside the tube furnace 10 caused by excessively fast advancement. The graphite sample undergoes an oxidation reaction in the high-temperature oxygen-rich environment of the central isothermal zone, and the sulfur element inside the sample is oxidized to generate sulfur dioxide gas. The generated sulfur dioxide gas is mixed in the carrier gas and transported through the gas delivery pipeline 30 to the electrolytic cell 21 inside the detection host 20 to be absorbed by the electrolyte.

[0044] S1022, the microcontroller continuously acquires the titration potential signal of the indicator electrode at a fixed sampling frequency. The indicator electrode is immersed in the electrolyte of the electrolytic cell 21. When sulfur dioxide gas enters the electrolytic cell 21 and undergoes chemical absorption, the concentration of the effective component in the electrolyte changes, causing physical fluctuations in the titration potential signal output by the indicator electrode. The microcontroller converts the continuous analog signal output by the indicator electrode into a discrete digital signal through its internally integrated analog-to-digital converter. The fixed sampling frequency ranges from 8Hz to 15Hz, and can be specifically set to 10Hz. This sampling frequency can completely record the transient change characteristics of the titration potential signal, while avoiding excessively high frequencies that would increase the computational load on the microcontroller. Before performing derivative calculations, the microcontroller performs a moving average filter on the digital signal to eliminate electromagnetic interference and baseline high-frequency noise generated by liquid stirring, preventing numerical divergence in subsequent differential calculations. The window width of the moving average filter ranges from 5 to 10 sampling periods. For the peripheral filtering circuit and signal conditioning amplification circuit of the analog-to-digital converter, those skilled in the art can make conventional configurations according to the actual sensor output characteristics. The hardware circuit design is a well-known technology in this field and will not be described in detail here.

[0045] S1023, the microcontroller performs time derivative calculations on the filtered titration potential signal to obtain the first and second derivatives of the titration potential. Since the release of sulfur dioxide gas during oxidation of the graphite sample in the isothermal region often exhibits a nonlinear acceleration process, relying solely on the first derivative can easily lead to response lag. By calculating the second derivative, the rate of change of sulfur dioxide concentration in the pipeline can be determined in advance. Because the signal acquired by the microcontroller is discrete time-series data, the microcontroller internally uses a finite difference algorithm to implement the time derivative process. Based on the titration potential values ​​at the current sampling time and historical sampling times, the microcontroller calculates the potential change within adjacent sampling periods. The first derivative of the titration potential characterizes the instantaneous absorption rate of sulfur dioxide gas entering the electrolytic cell 21. The second derivative of the titration potential characterizes the acceleration of the change in sulfur dioxide concentration in the pipeline. The specific finite difference calculation formula executed by the microcontroller is as follows:

[0046] ;

[0047] ;

[0048] In the above formula, Represents the discrete-time sequence number; Representing the The first derivative of the titration potential at each sampling time; Representing the Second derivative of titration potential at each sampling time; Representing the The titration potential signal at each sampling time; and Representing the first The and the first Titration potential signals at each historical sampling time; The value represents the sampling period and is equal to the reciprocal of the fixed sampling frequency. The microcontroller stores the calculated first and second derivatives of the titration potential in its internal registers as decision parameters for subsequent airflow modulation and motor control.

[0049] See attached document Figure 3 The specific implementation process of step S103 is explained in detail. Step S103 specifically includes the following sub-steps:

[0050] S1031, there is a physical spatial distance between the central isothermal zone of the tube furnace 10 and the electrolytic cell 21 inside the detection host 20, formed by components such as the gas delivery pipeline 30. The sulfur dioxide gas generated by the rapid oxidation of the graphite sample in the central isothermal zone experiences a transmission delay due to the dead volume of the pipeline as it is transported along with the carrier gas in the gas delivery pipeline 30. This time lag in fluid transmission causes a phase delay in the control system. If the microcontroller relies solely on the absolute amplitude of the titration potential signal or its first derivative as the basis for control, a significant change in the potential signal indicates that a large amount of high-concentration sulfur dioxide gas has already been transported to the electrolytic cell 21. At this point, further gas flow control will result in incomplete electrolyte absorption. Therefore, the microcontroller needs to introduce the second derivative of the titration potential for pre-judgment.

[0051] S1032, the microcontroller retrieves the first and second derivatives of the titration potential stored in its internal registers in real time. The microcontroller then executes a conditional branch decision, comparing the first derivative of the titration potential with a preset flow modulation threshold, and simultaneously comparing the second derivative with a preset phase prediction acceleration threshold. The flow modulation threshold ranges from 1 mV / s to 3 mV / s. The phase prediction acceleration threshold ranges from 0.5 mV / s. 2 Up to 1.5mV / s 2The specific values ​​of the two thresholds mentioned above were obtained through prior calibration experiments. The calibration process involved burning a standard substance with a known sulfur content, recording the absorption efficiency of the electrolytic cell 21 at different carrier gas flow rates, and setting the rate of change of titration potential and its acceleration corresponding to the critical point where the absorption efficiency began to deviate from the ideal state (e.g., below 99%) as the flow modulation threshold and the phase prediction acceleration threshold, respectively. This setting corresponds to the upper limit of the concentration increase of sulfur dioxide gas that the electrolyte in the electrolytic cell 21 can completely absorb. For the low-level instruction set calls of the comparator and logic operation unit inside the microcontroller, those skilled in the art can perform conventional programming configuration according to the selected microprocessor chip manual. The code compilation and burning methods are well-known technologies in this field and will not be elaborated here.

[0052] S1033, when the microcontroller determines that the first derivative of the titration potential is less than the flow modulation threshold, and the second derivative of the titration potential is greater than or equal to the phase prediction acceleration threshold, it indicates that the absolute value of the sulfur dioxide gas concentration reaching the electrolytic cell 21 has not yet reached the conventional intervention standard, but the gas concentration growth acceleration shows a rapid upward trend, indicating that the high-concentration gas generated in the tubular furnace 10 is about to arrive along the pipeline. At this time, the microcontroller outputs a flow adjustment command to the gas mass flow controller to reduce the carrier gas flow rate entering the tubular furnace 10. The microcontroller sends a pre-intervention flow rate setting value to the gas mass flow controller. The value range of the pre-intervention flow rate setting value is 40% to 60% of the basic carrier gas flow rate. After receiving the setting value, the gas mass flow controller reduces the opening of the internal electromagnetic proportional valve, so that the actual carrier gas flow rate in the pipeline is quickly reduced to the pre-intervention flow rate setting value.

[0053] S1034, through the aforementioned step of reducing the carrier gas flow rate, the system directly reduces the linear velocity of the high-concentration sulfur dioxide gas in the gas transmission pipeline 30. This physical-level speed reduction operation prolongs the residence time of the gas inside the electrolytic cell 21, increases the contact reaction cycle between the gas and the electrolyte, and ensures that the arriving high-concentration sulfur dioxide gas is completely absorbed. This operation eliminates the control phase lag error caused by pure fluid lag, providing conditions for subsequent steady-state gas flow closed-loop regulation of the system.

[0054] See attached document Figure 3 The specific implementation process of step S104 is explained in detail. Step S104 specifically includes the following sub-steps:

[0055] S1041, the microcontroller compares and calculates the first derivative of the titration potential in real time. When the first derivative of the titration potential is greater than or equal to the flow modulation threshold and less than the preset limit yield threshold, the system determines that the current oxidation reaction has entered the steady-state regulation range. The limit yield threshold ranges from 5 mV / s to 8 mV / s. The specific method for determining this threshold is as follows: through a pre-conducted limit load experiment, the rate of introduction of high-concentration sulfur dioxide gas is artificially increased. When unabsorbed sulfur dioxide gas molecules are captured by an external detection instrument at the exhaust port of electrolytic cell 21, the first derivative of the titration potential of the indicator electrode corresponding to this critical moment is recorded and set as the limit yield threshold. The logic for determining this range is that the absorption rate of sulfur dioxide gas in electrolytic cell 21 has reached the rated processing limit set by the system, but has not yet triggered a state exceeding the maximum absorption load of the electrolyte.

[0056] In state S1042, the microcontroller sends a braking command to the sample feed drive motor 40, pausing its propulsion. The microcontroller locks the current absolute position of the discharge tube 12 by reading the real-time position data transmitted from the position sensor 41. Pausing propulsion stops the graphite sample from moving into the region with a higher temperature gradient within the tube furnace 10, preventing the high-temperature oxidation reaction rate on the graphite surface from further increasing, thereby stopping the increase in the sulfur dioxide gas generation rate.

[0057] S1043, to maintain the titration reaction in electrolytic cell 21 in a dynamic equilibrium state and prevent unreacted sulfur dioxide gas from escaping with the bursting of bubbles, the microcontroller adjusts the carrier gas flow rate in real time based on the current gas release rate. The microcontroller calculates the target carrier gas flow rate based on the base carrier gas flow rate, the preset proportional adjustment coefficient, and the difference between the first derivative of the titration potential and the flow modulation threshold. The specific proportional negative feedback calculation formula executed internally by the microcontroller is as follows:

[0058] ;

[0059] In the above formula, Represents the target carrier gas flow rate; Represents the basic carrier gas flow rate; Represents the proportional adjustment coefficient; The first derivative of the titration potential represents the current sampling period; This represents the flow modulation threshold.

[0060] S1044, Regarding the parameter settings in the above formula, the proportional adjustment coefficient ranges from 50 (mL·s) / (min·mV) to 150 (mL·s) / (min·mV). The specific value of this proportional adjustment coefficient is determined based on the actual volume of the electrolytic cell 21 and the micropore size of the gas distribution plate at the end of the gas delivery pipeline 30. For the experimental tuning and adaptive adjustment of the proportional parameters of this type of control system, those skilled in the art can use conventional step response testing methods to obtain the parameters. The specific parameter tuning steps are well-known in the field and will not be elaborated here. Furthermore, to prevent the calculated target carrier gas flow rate from being too low, leading to internal depressurization of the tubular furnace 10, the microcontroller compares the calculated target carrier gas flow rate with the system's preset minimum sustaining flow rate before outputting control commands. If the calculated target carrier gas flow rate is less than the minimum sustaining flow rate, the microcontroller forcibly assigns the target carrier gas flow rate to the minimum sustaining flow rate. The minimum sustaining flow rate ranges from 150 mL / min to 250 mL / min. This minimum maintenance flow rate ensures that the gas pressure inside the gas pipeline 30 is always greater than the static pressure of the liquid column inside the electrolytic cell 21, thus preventing electrolyte backflow by maintaining a positive pressure state.

[0061] In step S1045, the microcontroller converts the target carrier gas flow rate, after lower limit constraint verification, into a corresponding analog control voltage or digital communication command, and sends it to the gas mass flow controller. The gas mass flow controller adjusts the opening of its internal electromagnetic proportional valve based on the target carrier gas flow rate, smoothly reducing the actual carrier gas velocity in the pipeline to the target value. After implementing this negative feedback closed-loop modulation of the gas flow, the volume of the carrier gas bubbles entering the electrolytic cell 21 decreases, and their rising speed slows down, extending the residence time of the gas inside the electrolyte. This ensures sufficient chemical contact between the sulfur dioxide gas and the electrolyte, preventing the escape of high-concentration sulfides during testing.

[0062] See attached document Figure 1 To be continued Figure 3 The specific implementation process of step S105 is explained in detail. Step S105 specifically includes the following sub-steps:

[0063] S1051, the microcontroller continuously monitors the first derivative of the titration potential during each sampling cycle. When the first derivative of the titration potential is greater than or equal to the preset limit threshold, the system determines that the concentration of sulfur dioxide gas entering the electrolytic cell 21 has exceeded the maximum absorption load of the electrolyte. If no cooling measures are taken, unreacted sulfide gas will escape from the liquid surface, causing the test data to be too low. The microcontroller then outputs a reverse command to the sample feeding drive motor 40, controlling the discharge tube 12 carrying the quartz boat 13 to pull back towards the lower-temperature preheating zone, thereby suppressing the oxidation reaction rate of the graphite sample by reducing the ambient temperature of the sample.

[0064] S1052, during the retraction of the discharge pipe 12 towards the preheating zone, the retraction action of the discharge pipe 12 will cause a volume change in the sealed inner cavity of the tubular furnace 10, creating a suction effect. The retraction action will free up additional space inside the tubular furnace 10. If the retraction speed of the discharge pipe 12 is too fast, causing the rate of volume expansion inside the tubular furnace 10 to exceed the target carrier gas flow rate currently input by the gas mass flow controller, a negative pressure will be instantaneously formed inside the tubular furnace 10 and the gas supply pipeline 30. This negative pressure will overcome the static pressure of the liquid column in the electrolytic cell 21, causing the electrolyte to be drawn back into the high-temperature furnace cavity along the gas supply pipeline 30, resulting in the rapid cooling and rupture of the high-temperature tube and electrolyte contamination of the gas path.

[0065] S1053, the microcontroller calculates the critical rate of retraction expansion based on the current real-time target carrier gas flow rate and the cross-sectional area of ​​the discharge pipe 12. The critical rate of retraction expansion is the maximum allowable linear velocity of the discharge pipe 12 without inducing negative pressure inside the pipe. In physical principle, when the discharge pipe 12 is pulled out of the sealed tubular furnace 10, the physical volume occupied by its external mechanical contour is simultaneously removed, thus creating an equal volume void inside the tubular furnace 10. The specific fluid dynamics constraint calculation formula executed internally by the microcontroller is as follows:

[0066] ;

[0067] In the above formula, Represents the critical rate of yield expansion; Represents the target carrier gas flow rate; This represents the cross-sectional area of ​​the discharge pipe 12; Represents the safety margin coefficient; This represents the dimensional conversion factor.

[0068] S1054, Regarding the range and determination method of the above parameters, the discharge pipe 12 is made of high-temperature resistant quartz material, and its outer diameter is generally 12mm to 16mm. Those skilled in the art can obtain its precise outer diameter and calculate the cross-sectional area of ​​the outer wall using conventional calipers. The safety margin factor ranges from 0.7 to 0.9, and can be specifically set to 0.8. This factor is set to compensate for the uneven thermal expansion of the high-temperature gas inside the tube furnace 10 and the volumetric flow rate deviation caused by the lag in the response time of the gas mass flow controller, ensuring that the system always maintains a safety margin during dynamic adjustment. The dimensional conversion factor is used to unify the units of different physical quantities, for example, when the unit of the target carrier gas flow rate is mL / min and the unit of the outer wall cross-sectional area is mm. 2 When the unit requirement for the yield expansion critical rate is mm / s, the dimensional conversion factor is set to 1 / 60×1000 (or 1000 / 60) to ensure that the value output by the microcontroller directly corresponds to the correct physical linear velocity.

[0069] S1055, the microcontroller, based on the calculated critical rate of yield expansion, controls the sample delivery drive motor 40 to pull the discharge tube 12 back towards the preheating zone at a speed not exceeding this critical rate. In specific implementation, the pull-back speed of the sample delivery drive motor 40 is limited to the critical rate of yield expansion. The microcontroller combines this critical rate with the lead parameter of the linear slide mechanism to convert it into a corresponding pulse transmission frequency, controlling the stepper motor to achieve the fastest yield cooling within the safety boundary. When the microcontroller detects that the first derivative of the titration potential has fallen back to the safe range, the sample delivery drive motor 40 stops pulling back and resumes its pushing action.

[0070] S1056, in addition to the asymmetric anti-backflow constraint control at the software control algorithm level, this invention incorporates a unidirectional isolation chamber 31 connected in series on the gas pipeline 30 as a physical anti-backflow structure. The unidirectional isolation chamber 31 contains a microporous glass core 32. The microporous glass core 32 is densely packed with micron-sized pores. When an unexpected power outage or extreme operating conditions cause occasional transient negative pressure in the pipeline, the surface tension of the liquid within the pores of the microporous glass core 32 will generate capillary resistance. This resistance can withstand a certain value of reverse pressure difference, thereby forming a physical barrier that allows unidirectional gas flow and blocks liquid backflow. The specific pore size selection and capillary resistance calculation of the microporous glass core 32 can be configured by those skilled in the art based on conventional principles of fluid mechanics; this is well-known technology in the field and will not be elaborated upon here.

[0071] See attached document Figure 3 This section details the specific implementation process of mechanical pneumatic pressure disturbance feedforward compensation and net signal decoupling in step S106. Step S106 specifically includes the following sub-steps:

[0072] In step S1061, during the airflow modulation and yielding actions in the preceding steps, the gas mass flow controller dynamically adjusts the carrier gas flow rate, while the discharge pipe 12 undergoes variable-speed displacement within the tubular furnace 10. The transient changes in flow rate and rapid changes in physical volume disrupt the original pressure balance within the gas delivery pipeline 30, generating mechanical pressure fluctuations within the pipeline. When these pressure fluctuations are transmitted to the electrolytic cell 21, they alter the frequency of bubble formation and the escape volume within the electrolyte, causing a physical change in the thickness of the diffusion layer on the indicator electrode surface. The pressure fluctuations alter the bubbling kinetic energy of the gas entering the liquid, thereby affecting the local stirring flow field and mass transfer rate of the electrolyte. This physical disturbance, combined with the chemical titration reaction, results in an interfering potential signal on the indicator electrode. If this signal is not eliminated, the system will misinterpret this mechanical disturbance as a change in sulfur dioxide concentration.

[0073] S1062, the microcontroller reads the current target carrier gas flow rate from the gas mass flow controller and the current operating linear velocity of the injection drive motor 40 in real time. Within adjacent sampling periods, the microcontroller performs differential calculations on the target carrier gas flow rate to obtain the rate of change of the carrier gas flow rate, and simultaneously performs differential calculations on the operating linear velocity to obtain the displacement acceleration. The rate of change of the carrier gas flow rate characterizes the intensity of the dynamic pressure disturbance at the gas source end. The displacement acceleration characterizes the intensity of the static pressure disturbance caused by the volume change. Since the mechanical disturbance is generated at the end of the tubular furnace 10, while the potential signal is acquired at the electrolytic cell 21 at the end of the pipeline, there is a physical aerodynamic transmission delay time in the propagation of the pressure wave in the gas delivery pipeline 30. The microcontroller stores the calculated rate of change of the carrier gas flow rate and displacement acceleration in a historical data circular queue, and extracts the variable data corresponding to the historical moment based on the aerodynamic transmission delay time for subsequent calculations to ensure accurate alignment of the compensation signal and the actual physical disturbance in the time domain. Because the target carrier gas flow rate changes dynamically, the microcontroller acquires the internal volume of the gas delivery pipeline 30 in real time, and calculates the pneumatic transmission delay time based on the current target carrier gas flow rate. This time is then divided by the sampling period to obtain the delay cycle number. The pneumatic transmission delay time typically ranges from 0.2s to 1.5s.

[0074] S1063, the microcontroller substitutes the extracted carrier gas flow rate change rate and displacement acceleration (after time delay matching) into a preset pressure and potential coupling transfer model to calculate the feedforward potential offset. The specific calculation formula executed internally by the microcontroller is as follows:

[0075] ;

[0076] In the above formula, Representing the Feedforward potential offset per sampling period; Representing the The rate of change of carrier gas flow rate over a historical sampling period; Representing the Displacement acceleration for each historical sampling period; Represents the number of delayed beats; Represents the flow-pressure coupling coefficient; This represents the volumetric pressure coupling coefficient.

[0077] S1064, Regarding the parameters in the above formula, the value range of the flow-pressure coupling coefficient is 0.01 (mV·s) / (mL / min) to 0.05 (mV·s) / (mL / min). The value range of the volumetric pressure coupling coefficient is 0.02 (mV·s). 2 ) / mm to 0.1(mV·s 2The specific values ​​of the two coupling coefficients mentioned above were determined through a pre-conducted blank control experiment. Specifically, in a cold blank condition without graphite sample loading and heating, the microcontroller control system applied a step-like flow rate change command and a motor acceleration command. The peak value of the baseline potential fluctuation output by the indicator electrode was recorded. By performing a linear regression fitting between this peak value and the input flow rate change rate and acceleration, the precise coupling coefficient corresponding to the current hardware geometry of the system could be obtained.

[0078] In step S1065, after acquiring the feedforward potential offset, the microcontroller subtracts this offset from the measured titration potential signal value in the current sampling period in real time. Through this numerical subtraction, the system removes the error component caused by physical pressure fluctuations from the original potential signal, which contains mechanical disturbance noise, extracting a net potential signal that only characterizes the change in sulfur dioxide chemical concentration. This net signal decoupling process eliminates the systematic interference caused by dynamic flow regulation and physical yielding actions on subsequent sulfur content integration calculations. For the subtraction operation processing and data register configuration of the microcontroller's internal arithmetic logic unit, those skilled in the art can refer to the processor datasheet for conventional settings. The writing of its underlying digital signal processing instructions is well-known in the field and will not be elaborated upon here.

[0079] See attached document Figure 3 The specific implementation process of step S107 is explained in detail. Step S107 specifically includes the following sub-steps:

[0080] In step S1071, after receiving the net potential signal from the decoupling output in step S106, the microcontroller compares it in real time with the titration endpoint potential setpoint stored internally. The titration endpoint potential setpoint corresponds to the initial chemical equilibrium state of the electrolyte in the electrolytic cell 21 when it has not absorbed sulfur dioxide gas. The value range of the titration endpoint potential setpoint is typically 80mV to 150mV, with the specific value determined by the electrolyte formulation and the material characteristics of the indicator electrode. When the microcontroller determines that the net potential signal deviates from the endpoint potential setpoint, it indicates that the concentration of the titrant in the electrolytic cell 21 has decreased due to a chemical reaction with sulfur dioxide. The control algorithm inside the microcontroller outputs a corresponding digital control quantity to the digital-to-analog converter based on the magnitude of the deviation, thereby driving the subsequent voltage-controlled constant current source circuit. The voltage-controlled constant current source circuit controls the electrolytic electrodes inside the electrolytic cell 21 to generate a corresponding electrolytic current, which generates the titrant through an electrochemical reaction to neutralize the absorbed sulfur dioxide. Iodide ions in the electrolyte lose electrons at the electrolytic anode under the influence of a constant current and are oxidized to elemental iodine. The generated elemental iodine then oxidizes sulfur dioxide, which enters the electrolyte with the carrier gas, into sulfuric acid, while simultaneously being reduced back to iodide ions. The entire process constitutes a catalytic redox cycle that consumes electrical energy to equivalently consume sulfur dioxide. For the hardware circuit topology and feedback regulation network of the voltage-controlled constant current source, those skilled in the art can use conventional operational amplifiers and power transistors to build it; the hardware circuit design is well-known in the field and will not be elaborated further here.

[0081] S1072, throughout the entire electrochemical neutralization reaction, the microcontroller synchronously acquires the actual electrolytic current value output by the voltage-controlled constant current source at a fixed integration period. Specifically, the microcontroller reads the voltage drop signal across the high-precision sampling resistor connected in series in the electrolytic circuit via its internal analog-to-digital converter, and calculates the actual current flowing through the electrolytic cell 21 according to Ohm's law. This realistic current sampling method avoids integration errors caused by thermal drift in the hardware circuit. The microcontroller uses its internal arithmetic logic unit to accumulate the product of the electrolytic current and the corresponding time interval within each discrete sampling period, achieving numerical integration of the coulombic charge. When the net potential signal recovers to the titration endpoint potential set value, and this state lasts for more than the preset endpoint determination time threshold, the system determines that the sulfur element in the current graphite sample has been completely oxidized and absorbed by the electrolyte for titration. The endpoint determination time threshold ranges from 10s to 30s. At this point, the microcontroller stops the current accumulation operation and records the total power consumption of the entire titration cycle. The specific formula for calculating the discrete coulombic integral executed by the microcontroller is as follows:

[0082] ;

[0083] In the above formula, Represents total power consumption; Represents the total number of sampling beats; Representing the The actual electrolytic current for each integration cycle; This represents the integration period.

[0084] S1073, after obtaining the total power consumption, the microcontroller converts the power consumption data into the mass of sulfur released from the graphite sample according to Faraday's law of electrolysis. In the absorption system using potassium iodide solution as the electrolyte, the electrolysis to generate 1 mol of iodine requires 2 mol of electron transfer, and 1 mol of iodine corresponds to the oxidation of 1 mol of sulfur dioxide. Considering the inevitable presence of trace amounts of sulfur trioxide byproducts in the high-temperature tube furnace 10, and the fact that the Faraday current efficiency inside the electrolytic cell 21 cannot reach an absolutely ideal state, the microcontroller introduces a system calibration coefficient for error compensation in this conversion step. The microcontroller internally retrieves preset chemical constants for multiplication and division operations. The specific formula for calculating the mass of sulfur is as follows:

[0085] ;

[0086] In the above formula, Represents the mass of sulfur; Represents total power consumption; The molar mass of sulfur is set at 32.06 g / mol. This represents the number of transferred electrons, which is assigned a value of 2 in the current system. This represents the Faraday constant, with a value set at 96485 C / mol; This represents the system calibration coefficient. The value range of the system calibration coefficient is usually from 0.95 to 1.05. The specific method for determining this coefficient is as follows: by conducting multiple repeated tests using standard samples with known sulfur content issued by the national standard material management agency, recording the ratio of the theoretically calculated mass to the actual known mass, and taking the arithmetic mean of the ratios from multiple tests as the system calibration coefficient, which is then stored in the microcontroller's memory.

[0087] S1074. In the actual test environment of the tubular furnace 10, trace amounts of background sulfur interference may exist in the system carrier gas, the quartz boat 13 itself, and the inner wall of the tubular furnace 10. To improve test accuracy, after calculating the sulfur element mass, the microcontroller needs to retrieve the blank mass deduction value obtained from the pre-performed blank calibration experiment. The microcontroller subtracts the blank mass deduction value from the calculated sulfur element mass to obtain the net sulfur mass. Finally, the microcontroller divides the net sulfur mass by the initial mass of the graphite sample entered by the operator before the test to calculate the final sulfur content percentage of the graphite sample. The microcontroller sends this final sulfur content percentage value to the display screen via the communication bus for numerical display, or stores it in non-volatile memory for subsequent data traceability. After data storage is completed, the microcontroller controls the reset of each hardware module, and the system enters standby mode, ready to execute the next sample analysis task.

Claims

1. A device for detecting sulfur content in graphite used in sealing gaskets, characterized in that, include: The tubular furnace (10) has a preheating zone and a central constant temperature zone inside. The sample inlet is equipped with a sample inlet bracket (11). The sample inlet bracket (11) is equipped with a sample inlet drive motor (40) and connected to a discharge tube (12). A position sensor (41) is installed next to the sample inlet drive motor (40). The discharge tube (12) carries a quartz boat (13). The sample inlet drive motor (40) drives the discharge tube (12) to move axially inside the tubular furnace (10). The detection host (20) integrates a gas mass flow controller, an electrolytic cell (21) and a microcontroller. The gas mass flow controller is connected to the gas inlet of the tube furnace (10). The electrolytic cell (21) is equipped with an indicator electrode. Its gas inlet is connected to the exhaust end of the tube furnace (10) via a gas pipeline (30). The gas pipeline (30) is connected in series to a one-way isolation gas chamber (31) with a microporous glass sand core (32) inside. The microcontroller is electrically connected to the sample injection drive motor (40), the position sensor (41), the gas mass flow controller and the indicator electrode respectively. The microcontroller is configured to perform time derivative calculation on the titration potential signal of the indicator electrode to obtain the first derivative and the second derivative of the titration potential, and use the first derivative and the second derivative of the titration potential as feedback parameters to adjust the carrier gas flow rate of the gas mass flow controller and the displacement state of the sample injection drive motor (40) in a closed loop.

2. A device for detecting sulfur in graphite for gaskets according to claim 1, characterized by The microcontroller has a preset flow modulation threshold, a limit backoff threshold, and a phase prediction acceleration threshold, wherein the limit backoff threshold is numerically greater than the flow modulation threshold. The microcontroller outputs control commands to the gas mass flow controller to establish a basic carrier gas flow rate, and controls the sample drive motor (40) to drive the discharge tube (12) to push the quartz boat (13) into the preheating zone of the tube furnace (10) for a preset time.

3. A device for detecting sulfur in graphite for gaskets according to claim 2, characterized by The microcontroller controls the sample feeding drive motor (40) to drive the discharge tube (12) to push the quartz boat (13) into the central constant temperature zone; The microcontroller continuously acquires the titration potential signal of the indicator electrode at a fixed sampling frequency, and performs time derivative calculation on the titration potential signal to obtain the first derivative and the second derivative of the titration potential.

4. A device for detecting sulfur in graphite for gaskets according to claim 3, characterized by When the first derivative of the titration potential is less than the flow modulation threshold and the second derivative of the titration potential is greater than or equal to the phase prediction acceleration threshold, the microcontroller outputs a flow adjustment command to the gas mass flow controller to reduce the carrier gas flow rate.

5. A device for detecting sulfur in graphite for gaskets according to claim 4, characterized by When the first derivative of the titration potential is greater than or equal to the flow modulation threshold and less than the limit yield threshold, the microcontroller pauses the propulsion action of the sample injection drive motor (40), calculates the target carrier gas flow rate based on the basic carrier gas flow rate, the preset proportional adjustment coefficient and the difference between the first derivative of the titration potential and the flow modulation threshold, and controls the gas mass flow controller to operate according to the target carrier gas flow rate.

6. A device for detecting sulfur in graphite for gaskets according to claim 5, characterized by When the first derivative of the titration potential is greater than or equal to the limit yield threshold, the microcontroller outputs a reversal command to the injection drive motor (40), calculates the yield expansion critical rate based on the target carrier gas flow rate and the cross-sectional area of ​​the discharge tube (12), and controls the injection drive motor (40) to drive the discharge tube (12) back towards the preheating zone at a running speed not greater than the yield expansion critical rate.

7. A device for detecting sulfur in graphite for gaskets according to claim 6, characterized by The calculation process for the critical rate of yield expansion is as follows: The target carrier gas flow rate is divided by the cross-sectional area of ​​the discharge pipe (12), and then multiplied by the safety margin coefficient and the dimension conversion coefficient to obtain the yield expansion critical rate.

8. A device for detecting sulfur in graphite for gaskets according to claim 7, characterized by The microcontroller extracts the rate of change of carrier gas flow and the displacement acceleration of the injection drive motor (40), inputs the rate of change of carrier gas flow and the displacement acceleration into a preset gas pressure and potential coupling transmission model to calculate the feedforward potential offset, and subtracts the feedforward potential offset from the measured titration potential signal to generate a net potential signal.

9. A device for detecting sulfur in graphite for gaskets according to claim 8, characterized by The calculation process for the feedforward potential offset is as follows: The feedforward potential offset is obtained by multiplying the carrier gas flow rate change rate by the flow-pressure coupling coefficient, multiplying the displacement acceleration by the volume pressure coupling coefficient, and adding the products of the two. The rate of change of carrier gas flow and the displacement acceleration are time-domain aligned and matched by the aerodynamic transmission delay time before being substituted into the pressure and potential coupling transmission model.

10. A device for detecting sulfur in graphite for gaskets according to claim 9, characterized by The microcontroller controls the detection host (20) to output electrolytic current in a closed loop according to the net potential signal, performs time integration calculation on the electrolytic current to obtain the total power consumption, and calculates the sulfur content percentage of the graphite sample according to Faraday's law of electrolysis.

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