Solution - Application of Gas Chromatography in Determining the Composition Content of Coke Oven Gas

Gas spectrum containing C2Gas spectrum containing C2/C3

Introduction:

In the process of producing coke through coking, the yellow brown gas mixture produced by the coal charging furnace during dry distillation in the coking chamber of the coke oven is called coke oven gas. The composition of coke oven gas is very complex, with a variety of toxic and harmful components, such as nitrogen-containing compounds, sulfur-containing compounds, hydrocarbons, etc. The main components include combustion luminescent components, combustion heating components, and inert gases.

At present, there are three methods for detecting the components of coke oven gas in China: the "Chemical Analysis Method for Main Components of Artificial Gas" GB12205-90 standard, the "Gas Chromatography Analysis Method for Constant Components of Artificial Gas and Liquefied Petroleum Gas" GB/T 10410-2008 standard, and the "Gas Chromatography Analysis Method for Components of Coke Oven Gas" GB/T 28901-2012 standard. Among them, GB12205-90 is measured using an Austrian gas analyzer, which has a slow measurement speed and large errors. GB/T 10410-2008 and GB/T 28901-2012 use gas chromatography to analyze the components of coke oven gas, but multiple injections are required to obtain three spectra, which is not only inefficient but also unable to display all component peak information on one spectrum, which brings unnecessary trouble to quantitative result calculation.

In order to improve analysis accuracy, shorten analysis time, increase work efficiency, simplify analysis methods, and facilitate quantitative result calculation, we have developed a three valve five column gas chromatography solution specifically for coke oven gas analysis. This analysis solution uses gas chromatography to determine crude gas and purified main product net gas. The main components measured include hydrogen H2, oxygen O2, carbon monoxide CO, carbon dioxide CO2, nitrogen N2, methane CH4, ethylene C2H4, ethane C2H6, propylene C3H6, propane C3H8, and so on. The instrument adopts an automated process of dual thermal conductivity detector (TCD), automatic injection, and automatic cutting. One injection can display the peak information of all components including H2, O2, N2, CH4, CO, CO2, C2H4, C2H6, C3H6, and C3H8 in coke oven gas on one spectrum.

Harmful components such as H2S, H2O, NH3, and nitrogen oxides that affect quantitative result calculations in the analysis are retained in the pre column and blown back, which does not affect the calculation of constant gas components. At the same time, it also improves the service life of the chromatographic analysis column, the stability and reliability of the analysis system.

Method principle:

Use a gas chromatograph with a thermal conductivity detector to separate the components in the sample using a dedicated column for coke oven gas, and record the peak height values of each component through a data processing system. Under the same operating conditions, the calibration normalization method is used to analyze the standard gas with known component content. The measured chromatographic peak height is compared with the standard gas spectral peak height to calculate the content of each component in the sample.

Experimental instruments:

Gas chromatograph model: Shanghai Jinghe AnalyElf G60 gas chromatograph (three valve five column dual TCD)

Nitrogen: 40L steel cylinder gas (purity>99.999%)

High purity hydrogen generator: XGH-300

Oil free air generator: XGA-2000

Gas chromatography conditions:

Experimental results:

Spectral diagram of standard sample results

Repeatability index of standard samples

Spectrum of C3H8 and C3H6 at a concentration of 100ppm

Conclusion:

This process can analyze the components such as H2, O2, N2, CH4, CO, CO2, C2H4, C2H6, C3H8, C3H6 in coke oven gas in 20 minutes. If C3 component analysis is not required, it can be shortened to 12 minutes. The reproducibility of each component is less than 3%. Propane and propylene can be detected at 100ppm, and other components can be detected at a minimum of 20-50ppm. This solution has high column load, high degree of automation, and high efficiency and accuracy. One injection can obtain the content of each component of coke oven gas, and can also provide calorific value calculation. This method meets the relevant requirements of GB/T 28901-2012 Gas Chromatography Analysis Method for Coke Oven Gas Components.