Self-adaptive nonlinear Kjeldahl apparatus titration control method

Abstract

The invention relates to a self-adaptive nonlinear Kjeldahl azotometer titration control method, which belongs to the technical field of chemical analysis instruments, and realizes accurate control of synchronous and efficient titration in a distillation process by dynamically calculating a titration rate by utilizing baseline adjustment and nonlinear control based on calculation of a color ratio and a relative ratio. And by introducing an acceleration and brake control mechanism, the titration efficiency is improved, and the robustness of the titration process is enhanced. In addition, by introducing an abnormal state monitoring mechanism, the operation state of the system is monitored in real time, and the stability of the equipment under the abnormal working condition is effectively guaranteed. The Kjeldahl apparatus titration control method disclosed by the invention is suitable for the fields of food, agriculture, environmental science and the like needing to accurately measure the nitrogen content, and has the characteristics of high precision, high efficiency, high stability, timeliness and automation.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis instruments, and in particular to a control method for an adaptive nonlinear Kjeldahl nitrogen analyzer. Background Art

[0002] The Kjeldahl method is a classic method for determining the nitrogen content in samples and is widely used in many fields. However, there are many problems in the operation of traditional Kjeldahl nitrogen analyzers, mainly manifested in the following aspects: the operation requires manual intervention and relies on the operator's judgment of color changes, which makes it difficult to control errors; the titration process is separated from the distillation process, and the analysis time is too long, which leads to side reactions and thus errors, thereby affecting the accuracy of the measurement results. In some attempts to perform distillation and titration simultaneously, problems such as rigid programs cannot respond to real-time changes in reaction conditions, inaccurate titration endpoint judgment, low distillation efficiency, and insufficient system stability are encountered. The traditional titration process usually needs to be carried out under static conditions and is very time-consuming.

[0003] This patent proposes an adaptive nonlinear Kjeldahl nitrogen analyzer titration control method that focuses on performing titration synchronously during the distillation process and monitoring the titration amount during the distillation process to achieve accurate and efficient determination of the nitrogen content. Summary of the Invention

[0004] To achieve simultaneous titration during the distillation process, the present invention proposes an adaptive nonlinear Kjeldahl nitrogen analyzer titration control method. This method addresses the problems of long analysis time, unstable titration control, and large errors in traditional nitrogen determination processes, as well as the impact of environmental changes caused by continuous evaporation and condensation on titration accuracy. By collecting color data of the titration reaction liquid in real time and performing dynamic titration control based on the real-time ratio of the color data, the accuracy and automation of the titration process are improved, achieving the effect of simultaneous titration during the distillation process.

[0005] To achieve the above purpose, the present invention provides the following solutions An adaptive nonlinear Kjeldahl nitrogen analyzer titration control method, comprising the following steps: S1: Real-time acquisition of color data of the titration reaction solution, including the red component value (R) and the blue component value (B); S2: Calculate the real-time ratio of the red component value to the blue component value (R / B), and calculate the relative color ratio based on the preset baseline value; S3: Automatically adjust the baseline value; S4: Calculate the precise titration rate using the nonlinear control formula; S5: Introduce acceleration and braking mechanisms to adjust the titration rate; C1: When the preset titration termination condition is met, the titration operation is triggered to stop; C2: When the distillation time is reached and the titration termination conditions are met, the titration is terminated and the final titration volume is calculated based on the titration volume data within the preset time window; otherwise, the titration continues.

[0006] Preferably, the formula for calculating the relative color ratio in S2 is relativeR = (R / B - baseline) / (1.0 - baseline).

[0007] Preferably, the nonlinear control in S3 includes: when the real-time ratio (R / B) is greater than the baseline value, calculating the relative ratio value according to the formula relativeR = (R / B - baseline) / (1.0 - baseline), and dynamically generating the titration rate output value through a nonlinear function, the formula is: when the real-time ratio (R / B) is less than or equal to the baseline value, controlling the titration rate to a maximum value (10,000 units). Preferably, the S3 acceleration and braking control mechanism: if the real-time ratio change rate Δ(R / B) is less than 0.002 and the brake flag is not triggered, the current titration rate is superimposed on the previous rate output value; if the real-time ratio change rate Δ(R / B) is less than -0.05, the titration rate is forced to be set to zero; if the real-time ratio change rate Δ(R / B) is greater than 0.005, the brake flag is triggered, the titration rate is set to zero, and the brake is released after a preset time. Preferably, the nonlinear control in S4 includes: when the real-time ratio (R / B) is greater than the baseline value, the titration rate output value is dynamically generated by a nonlinear function, the formula is When the real-time ratio (R / B) is less than or equal to the baseline value, the titration rate is controlled to the maximum value (10,000 units).

[0008] Preferably, the S5 acceleration and braking control mechanism: if the real-time ratio change rate Δ(R / B) is less than 0.002 and the braking flag is not triggered, the current titration rate is superimposed on the previous rate output value; if the real-time ratio change rate Δ(R / B) is less than -0.05, the titration rate is forcibly set to zero; if the real-time ratio change rate Δ(R / B) is greater than 0.005, the braking flag is triggered, the titration rate is set to zero, and the brake is released after a preset time.

[0009] Preferably, the titration termination condition in C1 is to stop the titration when the real-time ratio (R / B) ≥ terminalR and the red component value (R) is greater than the green component value (G) or the titration time exceeds a preset time.

[0010] Preferably, the titration is performed simultaneously during distillation.

[0011] Preferably, the color sensor, the titration execution module and the processor are configured to execute the control method according to any one of claims 1 to 6.

[0012] Effects and advantages of the adaptive nonlinear Kjeldahl nitrogen analyzer titration control method of the present invention: 1. This invention uses a high-precision 16-bit three-primary color digital signal color sensor to collect color data in real time, and the processed color ratio meets the real-time judgment requirement of the titration end point. The dynamic baseline compensation mechanism set according to the color ratio can significantly improve the titration efficiency in the middle and late stages of distillation, avoiding under-titration or excessive titration time due to reaction lag.

[0013] 2. This invention, based on the dynamic adjustment of baseline values ​​and relative color ratios, utilizes nonlinear functions to construct a dynamic response mechanism for titration rate, so that the titration rate and the reaction process form an S-shaped curve match. When approaching the titration endpoint, the titration rate will show an exponential decay trend, achieving smooth deceleration and a kinetic mechanism in which the chemical reaction rate gradually slows down.

[0014] 3. This invention's dual-mode mechanism, based on acceleration and braking, effectively improves titration efficiency and enhances control robustness. The acceleration mode rapidly superimposes the previous rate at the initial reaction stage or when the titration speed needs to be accelerated, shortening analysis time. The braking mode immediately triggers braking upon detecting a sudden change or anomaly in the color ratio, preventing overtitration. Furthermore, real-time anomaly monitoring and automatic process termination ensure system stability. This mechanism makes the titration process more flexible and precise, adapting to diverse reaction conditions and enhancing overall control performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of an adaptive nonlinear Kjeldahl nitrogen analyzer titration control method. DETAILED DESCRIPTION

[0016] The following is a detailed, clear and complete description of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of further restrictions, the elements defined by the sentence "include..." do not exclude the presence of other identical elements in the process, method, article or apparatus that includes the elements.

[0017] In an adaptive nonlinear Kjeldahl nitrogen titration control method, a high-precision RGB color sensor is used to capture the color change in the reaction solution in real time. The nonlinear control is performed by The formula is determined, and the baseline is set to control the titration in real time to achieve accurate control of the titration.

[0018] The detailed invention scheme of Example 1 and the experimental methods in each example without specific conditions are all carried out according to conventional conditions in the art or conditions recommended by the manufacturer.

[0019] Example 1 Provided is an adaptive nonlinear Kjeldahl nitrogen analyzer titration control method, specifically comprising: Purpose of the experiment: A method for adaptive nonlinear fully automatic Kjeldahl nitrogen analyzer titration control is provided.

[0020] Experimental steps: S1: Add ammonium sulfate standard sample to the digestion tube and insert the digestion tube into the Kjeldahl nitrogen analyzer. After starting distillation, use the TCS3200D-TR colorimeter to obtain color data in real time and perform data preprocessing. The collected RGB raw data is filtered to suppress noise interference, and then the red-to-blue color ratio (R / B) is calculated. S2: Calculate the relative color ratio. The calculation formula is as follows: ; S3: Adjust the baseline to set the initial baseline value to baseline=0.65, corresponding to the initial color state of the reaction. When R / B>baseline and output<10000, increase the baseline value by intervalV=0.001: , where the upper limit of the baseline value is 0.85 to prevent misjudgment of the endpoint due to over-adjustment; S4: Dynamically generate the non - linear control titration rate. If R / B ≤ baseline, the titration rate is the maximum value of 10,000 units (corresponding to full - speed titration); if R / B > terminalR, the rate is zero (terminate titration); if baseline < R / B and R / B ≤ terminalR, use a non - linear function to calculate the rate: , where the function outputs a value approaching zero when approaching the end point (relativeR → terminalR) to achieve smooth deceleration; S5: Acceleration and braking control. If the real - time rate of change of the ratio Δ(R / B) < 0.002 and the braking flag is not triggered, superimpose the previous rate output value: To cope with the insufficient rate caused by reaction lag, if Δ(R / B) < - 0.05, it is determined that the color drops suddenly, and the rate is immediately set to zero to prevent over - titration. If the real - time rate of change of the ratio Δ(R / B) > 0.05, the braking flag is triggered, the titration rate is set to zero, and the braking is released after a preset time; C1: Judge the titration termination condition. When the real - time ratio (R / B) ≥ terminalR and the red component value (R) is greater than the green component value (G) or the titration time exceeds the preset time, stop titration; otherwise, return to obtain the color ratio; C2: At this time, the conditions for titration termination are met, and it is necessary to further judge whether the distillation has ended at this time. If it has ended, directly terminate the titration and give the titration result; otherwise, return to obtain the color ratio.

[0021] Experimental results: Through the above process, multiple groups of experiments are carried out to accurately detect the color change in the titration reaction, accurately control the dosage in the titration, accurately observe and record the data error caused by environmental changes in the titration reaction, and accurately control the dosage in the distillation process to achieve accurate real - time detection of the nitrogen content.

[0022] In Example 1, an RGB tri - color sensor is used, which can recognize the full - spectrum range of 380 - 7,000 nm. Its color reproduction accuracy ΔE ≤ 0.5, which is much higher than the accuracy of the human eye (ΔE ≥ 1.5), providing support for the accuracy of titration and titration end - point judgment. The titration volume control uses a stepping motor with an accuracy of 2.5 μL / step, whose accuracy and stability are much higher than manual titration. Precise titration can be achieved by controlling the motor speed through PWM. Experimental data shows that the RSD of the titration results of standard samples can be as low as 0.2%.

[0023] In Example 1, when the titration rate monitored in real time falls below 10,000 units during the titration process, the system activates a dynamic baseline compensation mechanism: the baseline value is gradually increased in preset steps to optimize reaction kinetics. This strategy significantly improves titration efficiency in the middle and late stages of distillation, especially for high-nitrogen samples. If the titration endpoint has not been reached after the preset distillation cycle, continuous fine-tuning of control parameters can accelerate the titration rate, avoiding under-titration or excessive titration time due to reaction lag.

[0024] In Example 1, a nonlinear feedback control model was used to dynamically adjust the titration rate. This mechanism, by constructing an exponentially decaying control function, creates a nonlinear mapping between the titrant increment and the system error. As the theoretical endpoint is approached, the titration rate adaptively decays exponentially. This strategy effectively suppresses overshoot oscillations caused by linear control, ensuring the system response curve meets asymptotic stability requirements and maintaining a smooth color ratio curve during the experiment.

[0025] In Example 1, in the acceleration and braking control mechanism, control compensation is introduced in the acceleration stage to prevent the problem of slow titration caused by the exponential decay effect of the titration rate; the braking stage is mainly to avoid the drastic change in color ratio caused by excessive titration reaction or other interference factors, which can effectively suppress the overshoot phenomenon. The occasional bubble interference during the experiment causes a drastic change in color ratio and has no effect on the experimental results.

[0026] The fully automated Kjeldahl nitrogen determination system in Example 1 integrates distillation, titration, and analysis modules, achieving full process automation through precise timing control. In experiments, the system, based on a 5-minute distillation cycle, combined with a dynamic titration algorithm and online color monitoring, completed the entire process from initiating distillation of a standard sample to calculating the final nitrogen content in just 5-6 minutes. Data from multiple parallel experiments demonstrated excellent reproducibility, with relative standard deviations (RSDs) consistently below 0.5%, meeting the requirements of high-end analysis.

[0027] Those skilled in the art will appreciate that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0028] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0029] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited to this. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

[0030] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An adaptive nonlinear Kjeldahl nitrogen analyzer titration control method, characterized in that: The following steps are involved: S1: Real-time acquisition of color data of the titration reaction solution, including the red component value (R) and the blue component value (B); S2: Calculate the real-time ratio of the red component value to the blue component value (R / B), and calculate the relative color ratio based on the preset baseline value; S3: Automatically adjust the baseline value; S4: Calculate the precise titration rate using the nonlinear control formula; S5: Introduce acceleration and braking mechanisms to adjust the titration rate; C1: When the preset titration termination condition is met, the titration operation is triggered to stop; C2: When the distillation time is reached and the titration termination conditions are met, the titration is terminated and the final titration volume is calculated based on the titration volume data within the preset time window; otherwise, the titration continues.

2. The adaptive nonlinear Kjeldahl nitrogen analyzer titration control method according to claim 1, characterized in that: The relative color ratio in S2 is calculated using the formula relativeR = (R / B - baseline) / (1.0 - baseline).

3. The adaptive nonlinear Kjeldahl nitrogen analyzer titration control method according to claim 1, characterized in that: The adaptive adjustment of the baseline value in S3 is specifically as follows: when the real-time ratio (R / B) is greater than the current baseline value and the titration rate is less than 10000, the baseline value is gradually increased according to the formula baseline = baseline + intervalV until the preset upper limit value (0.85) is reached. The initial value of the baseline value is 0.65, and the adjustment step (intervalV) is 0.

001.

4. The adaptive nonlinear Kjeldahl nitrogen analyzer titration control method according to claim 1, characterized in that: The nonlinear control in S4 includes: when the real-time ratio (R / B) is greater than the baseline value, the titration rate output value is dynamically generated by the nonlinear function, and the calculation formula is: When the real-time ratio (R / B) is less than or equal to the baseline value, the titration rate is controlled to the maximum value (10,000 units).

5. The adaptive nonlinear Kjeldahl nitrogen analyzer titration control method according to claim 1, characterized in that: The S5 acceleration and braking control mechanism: If the real-time proportional change rate Δ(R / B) is less than 0.002 and the braking flag is not triggered, the current titration rate is superimposed on the previous rate output value; If the real-time ratio change rate Δ(R / B) is less than -0.05, the titration rate is forced to be set to zero; if the real-time ratio change rate Δ(R / B) is greater than 0.005, the brake flag is triggered, the titration rate is set to zero, and the brake is released after the preset time.

6. The adaptive nonlinear Kjeldahl nitrogen analyzer titration control method according to claim 1, characterized in that: The titration termination condition in C1 is: when the real-time ratio (R / B) ≥ terminalR and the red component value (R) is greater than the green component value (G) or the titration time exceeds the preset time, the titration is stopped.

7. The method for controlling the titration of an adaptive nonlinear Kjeldahl nitrogen analyzer according to claim 1, wherein , the titration is carried out simultaneously with the distillation.

8. The adaptive nonlinear Kjeldahl nitrogen analyzer titration control method according to claim 1, characterized in that: The color sensor, titration execution module and processor are used to execute the control method described in any one of claims 1-6.

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