Method and system for online analysis of free chlorine

Abstract

The application provides a free chlorine online analysis method and system, comprising: according to the preliminary purification gas, the part of moisture is treated through the condenser, the remaining moisture molecules are captured by using the adsorption material, and the intermediate gas medium after drying is obtained; if there is an element corrosion risk in the intermediate gas medium, the optical surface is protected by the inert coating, and the optical path system after protection is determined; the influence of baseline drift and noise flooding is processed by using the ultraviolet spectral differential absorption spectrum method through the preliminary spectral characteristic map, and clear absorption peak data after correction is obtained; according to the comparison between the clear absorption peak data and the preset weak absorption standard curve, the matching degree of the free content is judged, and the concentration value under online monitoring is determined; if the concentration value exceeds the stable operation threshold value, the spectral scanning parameter is adjusted through the feedback loop, and the final measurement result after optimization is obtained.

Description

Technical Field

[0001] This invention relates to the field of information technology, and in particular to an online analysis method and system for free chlorine. Background Technology

[0002] In industrial production, the high-concentration hydrogen chloride gas produced after combustion in electrolytic synthesis furnaces is often accompanied by moisture, dust, and trace amounts of free chlorine. Online monitoring of this complex gaseous medium is crucial for process control, safe emissions, and equipment protection. Accurately determining the free chlorine content directly impacts production stability, environmental compliance, and the long-term reliability of downstream equipment, thus becoming a vital part of process analysis in the chemical industry. Currently, most monitoring methods struggle to maintain long-term stable operation when dealing with such gases. Moisture and acid mist easily form liquid films or crystals on optical surfaces, leading to severe attenuation of the optical signal; dust particles scatter and obstruct the light path, causing baseline drift. These defects do not stem from a single interference source but are amplified by the combined effects of multiple components in the gas, causing traditional optical detection to rapidly lose accuracy under actual operating conditions, frequently resulting in reading deviations or even complete failure. Particularly noteworthy is the sharp contradiction between the highly corrosive nature of high-concentration hydrogen chloride and the extremely low content of trace amounts of free chlorine. Hydrogen chloride gas continuously corrodes optical components. Once the mirror or lens is damaged, the light transmittance decreases, directly weakening the ability to capture weak absorption signals. Meanwhile, the concentration of free chlorine is typically only in the range of tens to hundreds of ppm, and its absorption characteristic signal is inherently very weak. Any attenuation of the optical path will further submerge this already small signal in noise, leading to a higher detection limit and insufficient sensitivity to meet process requirements. Therefore, how to effectively resist the damage of strong corrosion to the optical system while clearly capturing the extremely weak absorption characteristics of free chlorine in the harsh environment of high concentrations of hydrogen chloride, moisture, dust, and trace amounts of free chlorine, thereby achieving accurate, rapid, and stable online concentration measurement, has become a core technical challenge in gas analysis of electrolysis processes. Summary of the Invention

[0003] This invention provides an online analysis method for free chlorine, mainly comprising: High-concentration hydrogen chloride gas, accompanied by moisture and dust, is collected from the electrolytic synthesis furnace via a gas conduit. Dust particles are separated using a pre-set particulate filter membrane, yielding a pre-purified gas after dust removal. The pre-purified gas then passes through a condenser to process the moisture-laden portion, and residual moisture molecules are captured using an adsorbent material to obtain a dried intermediate gas medium. If corrosion risk is detected in the intermediate gas medium, an inert coating is applied to protect the optical surface, establishing a protected optical path system. The protected optical path system is used to detect trace amounts of free chlorine in the intermediate gas medium using ultraviolet (UV) spectroscopy, obtaining preliminary spectral characteristic data. The preliminary spectral characteristic data is then processed using UV differential absorption spectroscopy to address baseline drift and noise intrusion, resulting in corrected, clear absorption peak data. The clear absorption peak data is compared with a pre-set weak absorption standard curve to determine the matching degree of free chlorine content and the concentration value under online monitoring. If the concentration value exceeds the stable operating threshold, the spectral scanning parameters are adjusted via a feedback loop to obtain the optimized final measurement result.

[0004] This invention provides an online free chlorine analysis system, mainly comprising: a gas collection and preliminary purification module, used to collect high-concentration hydrogen chloride gas accompanied by moisture and dust from an electrolytic synthesis furnace through a gas conduit, and to separate dust particles using a preset particle filter membrane to obtain a pre-purified gas after dust removal; a moisture treatment and drying module, used to process the moisture-accompanying portion of the pre-purified gas via a condenser, and to capture the remaining moisture molecules using an adsorption material to obtain a dried intermediate gas medium; a corrosion protection and optical path determination module, used to protect optical surfaces with an inert coating and determine the protected optical path system if corrosion risk is detected in the intermediate gas medium; and a spectral detection and data acquisition module, used for... A protective optical path system is used to detect the intermediate gas medium using ultraviolet spectral absorption spectroscopy to obtain the absorption spectrum data of trace free chlorine, resulting in a preliminary spectral characteristic map. A spectral correction and peak extraction module is used to apply ultraviolet differential absorption spectroscopy to process the baseline drift and noise submersion effects using the preliminary spectral characteristic map, obtaining clear absorption peak data after correction. A concentration matching and judgment module is used to compare the clear absorption peak data with a preset weak absorption standard curve to determine the degree of matching of the free chlorine content and determine the concentration value under online monitoring. A feedback adjustment and optimization module is used to adjust the spectral scanning parameters through a feedback loop if the concentration value exceeds the stable operating threshold, obtaining the optimized final measurement result. The technical solution provided by this invention can include the following beneficial effects: This invention discloses an online method for analyzing free chlorine. This method addresses the unique operational scenario where high-concentration hydrogen chloride gas produced by electrolytic synthesis furnaces is accompanied by large amounts of moisture and dust, severely interfering with optical detection and making accurate online monitoring of trace free chlorine content difficult. It achieves a breakthrough through a combination of multi-stage purification and intelligent protection. First, a particulate filter membrane is used to separate dust, followed by condensation and deep dehumidification using adsorption materials to obtain a dry intermediate gas medium. Then, to address the risk of component corrosion, an inert coating is introduced to protect the optical surface, constructing a reliable optical path system. Based on this, laser spectral scanning is used to acquire the absorption spectrum data of trace free chlorine, and then Fourier transform infrared algorithms are used to effectively correct baseline drift and noise interference, obtaining clear absorption peaks. Finally, the concentration value is determined by comparison with a preset standard curve, and scanning parameters are optimized through concentration exceeding the threshold feedback, forming a closed-loop precise measurement. This invention solves the technical challenge of stable and accurate online monitoring of trace free chlorine in complex media of high humidity, high dust, and high corrosion, significantly improving measurement accuracy, reliability, and real-time performance, providing key technical support for the safe and stable operation of electrolytic processes. Attached Figure Description

[0005] Figure 1 This is a flowchart of an online analysis method for free chlorine according to the present invention.

[0006] Figure 2 This is a schematic diagram of an online free chlorine analysis system according to the present invention. Detailed Implementation

[0007] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0008] like Figures 1-2 This embodiment of an online analysis method for free chlorine may specifically include: S101, high-concentration hydrogen chloride gas, accompanied by moisture and dust, is collected from the electrolytic synthesis furnace via a gas conduit. A pre-set particulate filter membrane is used to separate the dust particles, resulting in a pre-purified gas after dust removal. In this embodiment, the electrolytic synthesis furnace, as the source of hydrogen chloride gas, typically has a complex internal environment. During production, the high-concentration hydrogen chloride gas is often not pure, but rather accompanied by a large amount of moisture and dust particles generated during production. If these dust particles directly enter the subsequent analysis system, they can easily cause pipeline blockage and even contaminate precision optical detection elements, severely affecting the stability and accuracy of online monitoring. Therefore, this embodiment first draws out this mixed gas via a gas conduit and uses a pre-set particulate filter membrane for physical separation. The pore size of this particulate filter membrane can be set according to the particle size distribution of dust particles in actual working conditions to ensure effective interception of the vast majority of solid impurities, thereby providing a relatively clean pre-purified gas for subsequent processing steps. S102, based on the portion of the pre-purified gas accompanied by moisture treated by a condenser, the remaining moisture molecules are captured using an adsorption material to obtain a dried intermediate gas medium. Considering that although the preliminary purified gas removes solid dust, it still contains a high concentration of moisture. The presence of moisture not only corrodes subsequent detection equipment, but more importantly, water molecules may cause absorption interference in the ultraviolet spectral region, or alter the optical properties of the gas due to condensation and liquefaction, leading to deviations in the final free chlorine measurement results. Therefore, this embodiment employs a two-stage dehumidification strategy. First, a condenser is used to cool the gas, causing most of the saturated water vapor in the gas to condense into liquid water and be discharged, achieving preliminary "coarse dehydration." Further, the gas after condensation may still retain a small amount of moisture molecules. Although this amount is small, it is still significant in high-precision trace analysis. Therefore, this embodiment continues to use adsorption materials for deep drying of the gas. The adsorption material can be a specific molecular sieve or desiccant with high affinity for water molecules but without chemical reaction with hydrogen chloride gas. Through this process, the remaining moisture molecules can be captured, ultimately obtaining an intermediate gas medium with a dryness level meeting the requirements of optical detection. This application embodiment enables in-depth control of gas humidity, minimizing background interference from moisture in spectral analysis. As an optional embodiment, in practical applications, the corrosiveness of gases is a key factor affecting instrument lifespan. That is, after S102, before entering the core optical detection unit, the system needs to assess the potential threat of the gas to the equipment. Based on this, this application embodiment further includes, after S102: S103, if a component corrosion risk is detected in the intermediate gas medium, the optical surface is protected with an inert coating, and the protected optical path system is determined. When a component corrosion risk is detected in the intermediate gas medium, it indicates that the gas is chemically reactive, or the material of the optical surface is sensitive to the current hydrogen chloride concentration.If the exposed optical surface comes into direct contact with the gas, it may cause lens fogging, mirror oxidation, or window corrosion, leading to a decrease in luminous flux and a deterioration in signal-to-noise ratio. Therefore, this embodiment of the application employs a protective mechanism, namely, protecting the optical surface with an inert coating. This inert coating is typically made of acid- and corrosion-resistant materials, such as Teflon or specific nano-coatings, which effectively isolate the corrosive gas from direct contact with the optical component substrate while maintaining good light transmittance. In this embodiment, the assessment of the presence of corrosion risk can be based on a combination of preset gas concentration thresholds, ambient temperature, and the material characteristics of the optical components. If a risk is confirmed, it is ensured that the gas flow path is entirely through a protected optical path system treated with an inert coating. In this case, users can confidently perform long-term online monitoring without frequently replacing corroded optical components. Through this embodiment, preventative protection of the optical system can be achieved, significantly extending the maintenance cycle and lifespan of the online analysis system and ensuring data reliability during long-term operation. S104, using a protected optical path system, the intermediate gas medium is detected by ultraviolet spectral absorption to obtain the absorption spectrum data of trace free chlorine, thus obtaining a preliminary spectral characteristic map. After determining the protected optical path system, this embodiment of the application will utilize this path to perform substantial optical detection on the intermediate gas medium. Since free chlorine molecules have characteristic absorption peaks in the ultraviolet band, this embodiment of the application selects ultraviolet spectral absorption as the detection method. Specifically, the ultraviolet beam emitted by the light source passes through the gas chamber filled with the intermediate gas medium (i.e., the protected optical path system), and the free chlorine molecules in the gas absorb light energy of a specific wavelength. The detector receives the light signal after passing through the gas and converts it into an electrical signal, thereby resolving the absorption spectrum data. It should be noted that this step obtains a preliminary spectral characteristic map. Due to the complexity of the industrial environment, in addition to the characteristic absorption signal of free chlorine, this preliminary map may also contain superimposed light source fluctuations, electronic circuit noise, and non-specific absorption of other trace background components in the gas. Although dust and moisture have been removed in the previous steps, baseline drift and random noise still exist. Therefore, although the preliminary spectral feature map obtained at this time contains core information, it is often not clear enough, and direct use for quantitative calculation may lead to large errors. To solve this problem and improve the sensitivity and accuracy of detection, this embodiment of the application will further process the data after S104. In S105, the influence of baseline drift and noise submersion is processed by ultraviolet differential absorption spectroscopy using the preliminary spectral feature map to obtain clear absorption peak data after correction. Since the preliminary spectral feature map is often mixed with various interference signals, such as baseline drift caused by slow changes in light source intensity and random noise generated by electronic devices, these factors can easily submerge the weak absorption signal of trace free chlorine, leading to measurement failure.To extract true and effective signals from complex backgrounds, this application introduces differential ultraviolet absorption spectroscopy (DOAS) for data processing. This method utilizes the difference between the narrow-band absorption characteristics of gas molecules and the broadband extinction characteristics of particulate scattering, removing broadband background through mathematical filtering, thereby effectively correcting baseline drift. In this application embodiment, by applying the differential absorption spectroscopy algorithm, the system can smooth high-frequency noise superimposed on the spectrum and separate low-frequency background interference from the total spectrum. After this series of processing operations, previously blurred or noise-masked characteristic peaks become visible, ultimately obtaining clear absorption peak data after correction. This data retains only the absorption structure of the rapidly changing portion directly related to free chlorine concentration, greatly improving the signal-to-noise ratio and laying a solid data foundation for subsequent high-precision quantitative analysis. S106, by comparing the clear absorption peak data with a preset weak absorption standard curve, the degree of matching of free chlorine content is determined, and the concentration value under online monitoring is determined. After obtaining high-quality clear absorption peak data, it needs to be converted into specific concentration values. This application embodiment pre-constructs a weak absorption standard curve, which is plotted under strictly controlled experimental conditions by calibrating the absorbance characteristics of different known concentrations of free chlorine gas and their corresponding values. During actual online monitoring, the system compares the real-time, clear absorption peak data with this standard curve. Specifically, the degree of matching between the measured data and the standard curve is calculated using the least squares method or other fitting algorithms. Since the preceding steps have eliminated most interference, this comparison process accurately reflects the true content of free chlorine in the gas. Based on the matching results, the system determines the concentration value under online monitoring through interpolation or regression calculations. This process not only achieves a leap from qualitative to quantitative analysis but also effectively ensures linearity and accuracy within the trace detection range due to the use of the standard curve comparison method, ensuring the authenticity and reliability of the monitoring data. S107, if the concentration value exceeds the stable operating threshold, the spectral scanning parameters are adjusted through a feedback loop to obtain the optimized final measurement result. In actual electrolytic synthesis production processes, fluctuations in operating conditions may cause drastic changes in the free chlorine content in hydrogen chloride gas. If the current concentration value exceeds the system's preset stable operating threshold—for example, if the concentration is too high, causing detector saturation, or if the concentration is too low, causing a weak signal—the originally fixed spectral scanning parameters may no longer be applicable, thus affecting the accuracy of the measurement. To address this issue, this application's embodiments design an intelligent feedback loop. When an abnormal concentration value is detected, the system automatically triggers a parameter optimization mechanism. Through the feedback loop, the system can dynamically adjust key parameters of the spectrometer, such as integration time, light source intensity, or number of scans. For example, when the concentration is too high, the integration time can be reduced to prevent saturation; when the concentration is too low, the number of scans can be increased to improve the signal-to-noise ratio.Through this adaptive adjustment, the system can maintain optimal detection conditions across different concentration ranges, thereby obtaining optimized final measurement results. This gives the analysis system provided in this application embodiment a wider dynamic range and stronger environmental adaptability. Corresponding to the online analysis method for free chlorine in the above embodiment, this application embodiment also provides an online analysis system for free chlorine. For ease of explanation, only the parts relevant to this application embodiment are shown. The system mainly includes: a gas collection and preliminary purification module, used to collect high-concentration hydrogen chloride gas accompanied by moisture and dust from the electrolytic synthesis furnace through a gas conduit, and to separate dust particles using a preset particle filter membrane to obtain a preliminary purified gas after dust removal. This module, as the system's inlet, undertakes the key task of physical dust removal, ensuring the smooth flow of subsequent gas paths. A moisture treatment and drying module, used to treat the moisture-accompanying portion of the preliminary purified gas via a condenser, and to capture the remaining moisture molecules using adsorption materials to obtain a dried intermediate gas medium. Through the combination of condensation and adsorption, this module effectively removes moisture interference, ensuring the dryness of the optical detection environment. The corrosion protection module protects optical surfaces with an inert coating and identifies the protected optical path system if corrosion risk is detected in the intermediate gas medium. This module embodies the system's preventative maintenance strategy, extending the lifespan of precision optical components through material protection. The spectral detection module uses the protected optical path system to detect trace amounts of free chlorine in the intermediate gas medium via ultraviolet absorption spectroscopy, obtaining preliminary spectral characteristic data. As the core sensing unit, this module performs the initial conversion between optical signals and chemical concentration information. The spectral correction module applies differential ultraviolet absorption spectroscopy to address baseline drift and noise intrusion using the preliminary spectral characteristic data, obtaining clear, corrected absorption peak data. This module utilizes advanced algorithms to extract effective feature signals from complex background noise. The concentration judgment module compares the clear absorption peak data with a preset weak absorption standard curve to determine the degree of matching of free chlorine content and the concentration value under online monitoring. This module is responsible for the final quantitative calculation, converting the optical signal into a user-readable concentration indicator. The parameter optimization module adjusts the spectral scanning parameters via a feedback loop if the concentration value exceeds the stable operating threshold, obtaining an optimized final measurement result. This module endows the system with intelligent adjustment capabilities, ensuring accurate measurement data even under fluctuating operating conditions.

[0009] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for online analysis of free chlorine, characterized in that, The method includes: High-concentration hydrogen chloride gas, accompanied by moisture and dust, is collected from the electrolytic synthesis furnace through a gas conduit. The dust particles are separated using a pre-set particle filter membrane to obtain the pre-purified gas after dust removal. Based on the portion of moisture accompanying the pre-purified gas after being treated by the condenser, the remaining moisture molecules are captured by adsorption materials to obtain a dried intermediate gas medium. If a risk of component corrosion is detected in the intermediate gas medium, the optical surface is protected with an inert coating to determine the protected optical path system. A protective optical path system was used to detect the intermediate gas medium by ultraviolet spectral absorption method, and the absorption spectrum data of trace free chlorine were obtained to obtain a preliminary spectral characteristic map. By applying differential absorption spectroscopy to the preliminary spectral characteristic maps, the effects of baseline drift and noise inundation were addressed, and clear absorption peak data after correction were obtained. By comparing the clear absorption peak data with the preset weak absorption standard curve, the degree of matching of the free content is determined, and the concentration value under online monitoring is determined. If the concentration value exceeds the stable operating threshold, the spectral scanning parameters are adjusted through the feedback loop to obtain the optimized final measurement result.

2. The method for online analysis of free chlorine according to claim 1, characterized in that, The process involves collecting high-concentration hydrogen chloride gas, accompanied by moisture and dust, from the electrolytic synthesis furnace via a gas conduit, and then separating the dust particles using a pre-set particle filter membrane to obtain a pre-purified gas after dust removal.

3. The method for online analysis of free chlorine according to claim 1, characterized in that, The process involves treating the moisture-laden portion of the initially purified gas via a condenser, then using an adsorption material to capture the remaining moisture molecules, resulting in a dried intermediate gas medium.

4. The method for online analysis of free chlorine according to claim 1, characterized in that, If a risk of component corrosion is detected in the intermediate gas medium, the optical surface is protected by an inert coating to determine the protected optical path system.

5. The method for online analysis of free chlorine according to claim 1, characterized in that, The protective optical path system detects the intermediate gas medium using ultraviolet spectral absorption to obtain the absorption spectral data of trace amounts of free chlorine, thus obtaining a preliminary spectral characteristic map.

6. The method for online analysis of free chlorine according to claim 1, characterized in that, The method involves using differential absorption spectroscopy with ultraviolet light to process baseline drift and noise inundation through preliminary spectral feature maps, thereby obtaining clear, corrected absorption peak data.

7. The method for online analysis of free chlorine according to claim 1, characterized in that, The method involves comparing clear absorption peak data with a preset weak absorption standard curve to determine the degree of matching of free content and thus determine the concentration value under online monitoring.

8. The method for online analysis of free chlorine according to claim 1, characterized in that, If the concentration value exceeds the stable operating threshold, the spectral scanning parameters are adjusted through a feedback loop to obtain the optimized final measurement result.

9. An online analysis system for free chlorine, characterized in that, The system includes: The gas collection and preliminary purification module is used to collect high-concentration hydrogen chloride gas, which is accompanied by moisture and dust, from the electrolytic synthesis furnace through a gas conduit, and to separate dust particles using a preset particle filter membrane to obtain preliminary purified gas after dust removal. The moisture treatment and drying module is used to process the moisture-accompanying part of the pre-purified gas through the condenser, and then use adsorption materials to capture the remaining moisture molecules to obtain a dried intermediate gas medium. The corrosion protection and optical path determination module is used to protect the optical surface with an inert coating and determine the protected optical path system if a risk of corrosion of the component is detected in the intermediate gas medium. The spectral detection and data acquisition module is used to detect intermediate gas media by ultraviolet spectral absorption using a protected optical path system, obtain the absorption spectral data of trace amounts of free chlorine, and obtain a preliminary spectral characteristic map. The spectral correction and peak extraction module is used to process the effects of baseline drift and noise inundation by applying ultraviolet differential absorption spectroscopy to the preliminary spectral feature map, and obtain clear absorption peak data after correction. The concentration matching and judgment module is used to compare the clear absorption peak data with the preset weak absorption standard curve to determine the degree of matching of the free content and determine the concentration value under online monitoring. The feedback adjustment and optimization module is used to adjust the spectral scanning parameters through a feedback loop if the concentration value exceeds the stable operating threshold, so as to obtain the optimized final measurement result.

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