An optical fiber sensing system and method for on-line monitoring of hydrogen and impurity content in petrochemical hydrogen-carrying pipelines

Abstract

The invention discloses an optical fiber sensing system and a method for online monitoring of contents of hydrogen and impurities of a petrochemical hydrogen-loaded pipeline. The system comprises a measuring gas guiding bypass pipe, an optical signal enhancement gas chamber, a light source unit, a signal detection unit, a signal demodulation unit, a data processing unit and the like, wherein laser emitted by the light source unit is guided into the optical signal enhancement gas chamber through optical fibers and optical cables and excites a Raman signal of gas; meanwhile, the signal detection unit transmits a signal detected by the detection unit to the signal demodulation unit positioned in a non-explosionproof zone through a transmission optical cable; demodulated data are transmitted to the data processing unit through an RS-485 serial port line for data processing and real-time display of measurement parameters. The system can simultaneously perform online monitoring of the contents of high-concentration hydrogen and impurity gases (such as CH4, CO, CO2 and H2S) in a process pipeline in industries such as petrifaction; in addition, a sensor is intrinsically safe, so that online monitoring of hazardous gases such as hydrogen is safer and more accurate.

Description

technical field [0001] The invention relates to a system and method for on-line monitoring of hydrogen concentration and impurity content, in particular to an optical fiber sensing system and method for on-line monitoring of hydrogen and impurity content in petrochemical hydrogen-carrying pipelines. Background technique [0002] At present, the hydrogen-carrying process is widely used in the petrochemical industry. Under the conditions of appropriate temperature, hydrogen concentration and pressure, it can generate chemical products such as hydrocarbons or alcohols with a certain molecular weight. Ethylene hydrogen is used in hydrocracking units and wax oil hydrogenation units, if the purity of ethylene hydrogen decreases (CH 4 , CO, CO 2 Impurity content rises), will reduce the system hydrogen partial pressure of above-mentioned hydrogenation unit, is unfavorable for hydrogenation reaction, has a strong impact on product quality. On the other hand, the ethylene hydrogen u...

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Problems solved by technology

Ethylene hydrogen is used in hydrocracking units and wax oil hydrogenation units, if the purity of ethylene hydrogen decreases (CH 4 , CO, CO 2 Impurity content rises), will reduce the partial pressure of hydrogen in the system of the above-mentioned hydrogenation unit, which is not conducive to the hydrogenation reaction and seriously affects the product quality

On the other hand, the ethylene hydrogen used by many enterprises is purchased from outside. Due to the limitation of the process, the ethylene hydrogen from the ethylene demethanizer inevitably contains a certain concentration of CH 4 , if the operation of the ethylene demethanizer is unstable, it will lead to CH in the ethylene hydrogen 4 The content increases, making the effective component H 2 Lower content, higher purchase price

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