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february 2023

Comment of the chief technologist to the article "Features of the use of methane-hydrogen fraction as fuel for boilers of power plants"

The chief technologist of ANO "Hydrogen Technology Solutions" B.A. Rybakov found a very interesting article: "Features of the use of methane-hydrogen fraction as fuel for boilers of power plants" and wrote his comments. The article was written by M.A. Taimarov, V.K. Ilyin, E.G. Chiklyaev, R.G. Sungatullin (Kazan State Power Engineering University).

Comment No. 1: "This article presents the results of measuring and comparing the combustion rate, the temperature at the outlet of the furnace and the concentration of nitrogen oxides in the flue gases of the TGM-84A power boiler with a capacity of 420 tons of steam per hour during the combustion of hydrogen-containing and natural gas."

Comment No. 2: "The article notes the influence of the heat of combustion of fuel gas on the temperature in the core of the torch":

Quote from the article: "The methane-hydrogen fraction is a by-product of a gaseous hydrocarbon during oil refining to produce final petroleum products. In connection with the prospective use of the methane-hydrogen fraction as an alternative fuel to natural gas for combustion in the power boilers of thermal power plants, it became necessary to study the combustion processes of the methane-hydrogen fraction in large volumes. The conversion of the OH1000/1 and OH-1000/2 furnaces from combustion of the methane-hydrogen fraction with a calorific value of 25.45 MJ/m3 to combustion of the composition with a calorific value of 18.8 MJ/m3 leads to a decrease in the temperature in the core of the torch by an average of 100 ° C."

Comment No. 3: "An increase in the concentration of hydrogen in the fuel gas leads to an increase in combustion speed".

Quote from the article: "The results of experiments obtained by the authors to determine the concentration of nitrogen oxides NOx and the combustion rate of the methane-hydrogen fraction in the OH-1000/1 furnace and the natural gas in the TGM-84A boiler, depending on the heat of combustion Qnr, showed that an increase in the hydrogen content of H2 from 10.05% (by weight) up to 18.36% leads to an increase in the combustion rate w by 45%. Speed of combustion of natural gas with a methane content of 98.89% CH4 in the boiler TGM-84A is 0.84 m / s, that is 2.5 times lower than the combustion rate of the methane-hydrogen fraction with a content of H2 10.05%."

Comment No. 4: "It should be noted that the article provides data on the mass concentration of hydrogen. Given the low value of the hydrogen density, this article is about conducting tests on the combustion of a gas mixture with a high volume concentration of hydrogen. For example, with a mass concentration of hydrogen in a methane-hydrogen mixture of 10% (90% methane), the volume concentration of hydrogen will be 48%.

With a mass concentration of hydrogen in a methane-hydrogen mixture of 18.8% (81.2% methane), the volume concentration of hydrogen will be 66%."

Comment No. 5: "Table 1 of the article provides data on the chemical composition and characteristics of hydrogen-containing gases (HG), such as density and lower heat of combustion, which were burned in the furnaces of the Ryazan refinery.

The mass concentration of hydrogen (H2) varies in the range from 11.04% to 18.36%, and the mass concentration of methane (CH4) – from 3.64% to 44.18%.

It is important to note that in the compositions of VSG shown in Table 1, along with hydrocarbons such as ethane, propane, butane, pentane and hexane, nitrogen (N2) with a mass concentration of 4.93% to 19.9% is present, as well as oxygen (O2) with a mass concentration of 1.35% to 6.18%."

Comment No. 6: "Table 2 shows data on the concentration of nitrogen oxides (NOx) in the flue gases of the TGM-84A boiler during the combustion of HCG with mass concentrations of hydrogen (H2) 10.1%, 10.05% and 18.36% and methane 28.3%, 28.27% and 18.28%, as well as natural gas (without hydrogen) with a mass concentration of 98.89% methane.

α is the coefficient of excess air.

NOx is the concentration of nitrogen oxides in the combustion products, reduced to one value of the excess air coefficient equal to 1.4.

From this table, it can be seen that in the presence of hydrogen in the fuel gas, NOx emissions are reduced compared to emissions of nitrogen oxides formed during the combustion of natural gas.

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