[Product Name]Analysis of Acetylene Content in Liquid Oxygen by Gas Chromatography

[Product Introduction]Acetylene is an unsaturated hydrocarbon with extremely low solubility in liquid oxygen, about 5.2 cm/L, and has high chemical activityinstable. Excess acetylene will be suspended in liquid oxygen as white solid particlesMedium, low explosion lower limit, explosion sensitivity *, causing distillation towerThe main source of the explosion.The air separation unit is an important device for urea production. Due to the presence of trace amounts of acetylene in liquid oxygen, when acetylene accumulates to a certain amount, it is easy to cause explosions. Therefore, it is necessary to regularly detect the content of acetylene. In order to meet the needs of rapid detection in workshop production, self-made chromatography columns are used for chromatographic analysis instead of colorimetric analysis, which is simple, fast, and highly accurate.

【 Principle of Measurement 】Based on the usage of gas chromatography, a hydrogen flame ionization detector (FID) is used to determine trace amounts of acetylene in liquid oxygen. FIDDuring work, carrier gas, hydrogen gas, and air are required. When hydrogen gas burns in air, there are very few ions in the flame, but if hydrocarbons are present, the ions increase significantly. When the carrier gas flowing out from behind the column and the sample are mixed with hydrogen gas and burned in air, organic compounds are ionized into positive and negative ions. Under the action of an electric field, the positive and negative ions generate a current relative to the mass of the combustion material. This ionization is amplified by a microcurrent amplifier and recorded by a data processing machine as a qualitative and quantitative basis.

Keywords: air separation equipment; Acetylene; testing; Gas chromatographAnalysis of Acetylene Content in Liquid Oxygen by Gas Chromatography

[Analysis steps]

1. Experimental instruments

2. The choice of adsorption is crucial in chromatographic analysis, as the separation degree of components is the key to accurate quantification. Therefore, an appropriate chromatographic column must be selected. The liquid oxygen gas source used in the experiment contains impurities such as ethane, ethylene, propane, etc. in addition to acetylene being tested. To separate these three impurities, TDK was first used as a packed column, but the spectrum showed poor separation efficiency and low sensitivity, making it unsuitable for use in this method. Then, self-made organic polymer microspheres were selected as the adsorption column, which had sufficient separation effect and high sensitivity. Organic polymer microspheres: particle size 0-177-0.25 mm.

3. Measurement conditions

Column temperature 65 ℃; Detector temperature 75.5 ℃; Carrier gas (N2): 0.07MPa; H2:0.05 MPa; Air:0.09 MPa; Chromatography column<3 mm × 4m stainless steel packed column (self-made); The injection volume is 1 ml.

3detection range

The experiment was prepared by diluting the steel cylinder standard sample10.1ppmThe sample with the lowest detection concentration is0.1ppm.

The reliability of this analysis method was tested using an external standard method for quantification, with a steel cylinder standard gas containing 10.6 × 10-6 acetylene.

Experimental instruments:GC2020Zhongkepu card

data processorN2000 Workstation Ak-2Air generator;HK-3Type hydrogen generator; The carrier gas is high-purity nitrogen.