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CN-122017060-A - Online monitoring system for gas purity of alkaline electrolytic tank

CN122017060ACN 122017060 ACN122017060 ACN 122017060ACN-122017060-A

Abstract

The invention discloses an online monitoring system for gas purity of an alkaline electrolytic cell, and aims to solve the problems of response lag, insufficient detection precision, insufficient suitability and the like in the prior art. The gas sampling, preprocessing, gas chromatography analysis and control alarm module is integrated in the analysis cabinet through modularized integrated design, is arranged at the outlet of the separator nearby, samples and detects on site, sampling points are accurately distributed in a downstream stable flow field area of the separator, the preprocessing module adopts a multistage purification link to ensure clean and dry gas and constant temperature, the gas chromatograph is provided with a mixed chromatographic column and a miniature thermal conductivity detector, so that second-level accurate detection of oxygen in hydrogen and hydrogen in oxygen is realized, and a closed-loop protection is formed by matching a safety interlocking mechanism. The spectrum detection module constructs a chromatography-spectrum dual detection cooperative framework, and is complementary with gas chromatography accurate calibration. The system remarkably improves the detection response speed and low-load suitability, ensures the safe and stable operation of the electrolytic tank, and is suitable for various alkaline water electrolysis hydrogen production scenes.

Inventors

  • ZHANG YU
  • ZHENG LINYI

Assignees

  • 江苏双良氢能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260112

Claims (10)

  1. 1. The online monitoring system for the gas purity of the alkaline electrolytic tank is characterized in that the online monitoring system is integrated in an analysis cabinet in a modularized mode, the analysis cabinet is arranged nearby near an outlet of a separator, and a gas sampling module, a pretreatment module, an analysis module and a control and alarm module are integrated in the analysis cabinet; the analysis module comprises a gas chromatograph, a gas analysis module and a gas analysis module, wherein the gas chromatograph is used for quantitatively analyzing components of the pretreated gas and detecting hydrogen and oxygen components in the gas; The control and alarm module is electrically connected with the analysis module, transmits detection data to the remote control end in real time, compares the detection data with a preset safety threshold, alarms when the detection data exceeds the threshold, and automatically cuts off the power supply of the electrolytic tank.
  2. 2. An on-line monitoring system of gas purity of an alkaline electrolyzer according to claim 1 characterized in that the gas chromatograph is equipped with a micro thermal conductivity detector (μ -TCD), a mixed chromatographic column consisting of a molecular sieve 5A chromatographic column for separating O 2 from H 2 , porapakQ chromatographic column for separating hydrocarbon impurities, and a PorapakQ chromatographic column, and a carrier gas supply unit.
  3. 3. The online monitoring system for gas purity of an alkaline electrolyzer according to claim 2, wherein the mixed chromatographic columns are connected in series, the gas inlet end of the molecular sieve 5A chromatographic column is connected with the sampling end of the gas outlet pipeline of the electrolyzer, and the gas outlet end of the PorapakQ chromatographic column is connected with the gas inlet of a micro thermal conductivity detector (μ -TCD); the carrier gas provided by the carrier gas supply unit is high-purity nitrogen, and the purity of the high-purity nitrogen is more than or equal to 99.999%; The carrier gas flow rate of the gas chromatograph main body is set to be 30mL/min, and the detection period is less than or equal to 30 seconds; The lower limit of the gas chromatograph main body for detecting the oxygen in the hydrogen is less than or equal to 0.2 percent, and the lower limit of the gas chromatograph main body for detecting the hydrogen in the oxygen is less than or equal to 2.0 percent.
  4. 4. The online monitoring system for gas purity of an alkaline electrolyzer of claim 1, wherein the sampling probe of the gas sampling module is made of hastelloy C-276, and the sampling point is arranged at 20D downstream of the electrolyzer separator.
  5. 5. The online monitoring system for the gas purity of the alkaline electrolytic tank according to claim 1, wherein the pretreatment module comprises a gas-liquid separator, an adsorption device and a cooling device which are sequentially arranged, the gas-liquid separator adopts a cyclone foam remover, solid desiccant and catalyst are filled in the adsorption device, and the cooling device is a spiral tube type heat exchanger or a double tube type heat exchanger, so that the gas temperature is reduced to 25+/-2 ℃.
  6. 6. The online monitoring system for the gas purity of the alkaline electrolytic tank according to claim 1, wherein the analysis module is a chromatographic-spectral dual-detection cooperative design and comprises a meteorological chromatographic module and a spectral detection module, the gas chromatographic module is accurate detection, and the spectral detection module is rapid detection through near infrared spectral detection, so that cooperative detection of rapid response and accurate calibration is formed.
  7. 7. The online monitoring system for gas purity of an alkaline electrolyzer of claim 6, wherein the spectral detection module comprises a detection channel comprising a laser light source emitting a specific laser to match the absorption peak of O 2 /H 2 , a photodetector capturing the laser absorption signal; The laser wavelength of the laser source is designed to set a characteristic absorption peak of 1.58 mu m for H 2 and a characteristic absorption peak of 760nm for O 2 ; The photoelectric detector is an indium gallium arsenide (InGaAs) high-speed detector; The detection point of the spectrum detection module is arranged in a homologous manner with the sampling end of the gas sampling module, mounting bases are arranged on two sides of the pipeline, and a laser source and a photoelectric detector are respectively mounted on the mounting bases on two sides, so that a laser beam transversely penetrates through the section of the pipeline perpendicular to the axis of the pipeline and irradiates on the photoelectric detector.
  8. 8. The online monitoring system for the gas purity of the alkaline electrolytic tank according to claim 7, wherein the spectrum detection module further comprises a reference channel for correcting the light intensity attenuation caused by alkali mist and water vapor in real time, the reference channel and the detection channel are integrated in the same optical housing to form a double-light-path parallel structure, a reference light source of the reference channel emits laser without an O 2 /H 2 absorption peak as a reference standard, and a reference detector is arranged on the other side of the pipeline together with a detector of the detection channel.
  9. 9. The online monitoring system for the gas purity of the alkaline electrolytic tank according to claim 1, wherein the alarm signal comprises an audible and visual alarm signal and a shutdown control signal for cutting off a power supply of the electrolytic tank, and the alarm logic is integrated with a DCS system, and synchronously triggers a shutdown command and a valve cut-off control command when a threshold value is exceeded.
  10. 10. An on-line monitoring system for gas purity of an alkaline electrolyzer according to claim 1, characterized by comprising the following monitoring method: S1, respectively collecting gas samples of a hydrogen outlet and an oxygen outlet of an alkaline electrolytic cell through a gas sampling module; S2, sequentially carrying out gas-liquid separation, adsorption and constant-temperature cooling on a sample by a pretreatment module, and then conveying the sample to a gas chromatograph; S3, detecting the content of oxygen in the hydrogen and hydrogen in the oxygen by a gas chromatograph through a micro thermal conductivity detector (mu-TCD) and a mixed chromatographic column to obtain a real-time detection value; s4, comparing the real-time detection value with a preset threshold value, triggering an alarm through an alarm module if the real-time detection value exceeds the preset threshold value, and outputting a control signal to an electrolytic tank control system.

Description

Online monitoring system for gas purity of alkaline electrolytic tank Technical Field The invention relates to the technical field of hydrogen production by alkaline water electrolysis, in particular to an online monitoring system for gas purity of an alkaline electrolytic tank. Background The alkaline electrolytic tank is used as core equipment for large-scale hydrogen production, and the purity monitoring of hydrogen and oxygen in the operation process is directly related to production safety and efficiency. In the prior art, the gas purity monitoring mostly adopts a mode of 'remote sampling and centralized analysis', namely, a gas sample at the outlet of a separator is transmitted to a central analysis laboratory through a long-distance pipeline, and detection is completed by means of equipment such as a gas chromatograph. On one hand, long-distance transmission leads to prolonged residence time of a gas sample in a pipeline, response delay can reach a plurality of minutes, rapid fluctuation of gas purity under a low-load working condition cannot be captured in time, namely, gas yield of an electrolytic tank is reduced during low load, residence time of the gas in a separator is shortened, separation efficiency is reduced, oxygen content in hydrogen is easy to rapidly rise to form explosive mixed gas, a delayed detection result can lead to missing of optimal disposal opportunity, on the other hand, a sampling pipeline is easy to be influenced by environmental temperature and humidity, alkali liquor fog drops are easy to adhere to a pipe wall and scale, sample components are distorted, meanwhile, a traditional pretreatment device is mostly dependent on spray washing and adsorbent purification, the problems of high water resource consumption and frequent adsorbent replacement exist, and operation and maintenance cost and shutdown risks are increased. In addition, the single detection means is difficult to consider the response speed and the detection precision, the traditional gas chromatograph can accurately quantify, but the detection period is longer, the real-time monitoring requirement under the fluctuation working condition can not be adapted, and part of the rapid detection technology is easily interfered by alkali mist and water vapor, and the detection stability is insufficient, so that the actual requirements of the large-scale and high-stability operation of the alkaline electrolytic tank are difficult to meet in the aspects of safety, suitability and economy of the conventional monitoring system. In view of the above, there is a need for an online monitoring system for gas purity of an alkaline electrolyzer to solve the above-mentioned problems. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide an online monitoring system for the gas purity of an alkaline electrolytic cell. In order to achieve the above purpose, the technical scheme of the invention is as follows: The online monitoring system for the gas purity of the alkaline electrolytic tank is integrated in an analysis cabinet in a modularized manner, the analysis cabinet is arranged nearby an outlet of a separator, and a gas sampling module, a preprocessing module, an analysis module and a control and alarm module are integrated in the analysis cabinet; the sampling end of the gas sampling module is respectively connected with a hydrogen outlet pipeline and an oxygen outlet pipeline of the alkaline electrolytic tank to form a nearby sample; The pretreatment module is arranged at the rear stage of the gas sampling module and is used for carrying out gas-liquid separation, adsorption and constant-temperature cooling treatment on the sampled gas; the analysis module comprises a gas chromatograph, which is used for quantitatively analyzing components of the pretreated gas and detecting hydrogen and oxygen components in the gas; The control and alarm module is electrically connected with the analysis module, transmits detection data to the remote control end in real time, compares the detection data with a preset safety threshold, alarms when the detection data exceeds the threshold, and automatically cuts off the power supply of the electrolytic tank. Further, the gas chromatograph is configured with a micro thermal conductivity detector (μ -TCD), a mixed chromatographic column consisting of a molecular sieve 5A chromatographic column for separating O 2 from H 2, porapakQ chromatographic columns for separating hydrocarbon impurities, and a PorapakQ chromatographic column, and a carrier gas supply unit. Furthermore, the connection mode of the mixed chromatographic column is serial connection, the air inlet end of the molecular sieve 5A chromatographic column is connected with the sampling end of the gas outlet pipeline of the electrolytic tank, and the air outlet end of the PorapakQ chromatographic column is connected with the air inlet of the micro thermal conductivity detector (mu-TCD); the carrie