A method for determining the composition content of coal pyrolysis products

Abstract

The invention discloses a method for determining content of coal pyrolysis resultant. The method comprises (1) obtaining the mass of C, H, O, N and S in 100 g dry ash-free basis coal by employing an element analysis process and respectively recording as mC, mH, mO, mN and mS g, and employing a coal industrial analysis process to measure the caloric value Q[net ,dnf] of combustible substances in dry ash-free basis coal and measure the mass of coke and volatile compounds generated after pyrolysis respectively to be mFC and mV g; (2) calculating the air quantity demanded by combustion of 100 g dry ash-free basis coal to be mA g according to a combustion chemical formula; (3) obtaining the value of a, b and c from a coal pyrolysis formula (1) according to the data in the step (1) by balancing the mole numbers of N and S elements, thereby respectively determining the substance amount of C, N and S elements in coal, and calculating x[i] values according to a formula (14) by employing a process of solving a minimum value of a function, thereby determining the content of H2O, CO, CO2, a hydrocarbon mixture and H2.

Description

technical field [0001] The invention belongs to the field of thermal energy engineering, and in particular relates to a method for determining the composition content of coal pyrolysis products. Background technique [0002] The combustion of pulverized coal has to go through stages such as pyrolysis of organic matter, combustion of volatile matter, and heterogeneous reaction of coal char. Pyrolysis is the first step of pulverized coal combustion, and the mass of volatile matter precipitated in this process accounts for about 10% to 50% of the mass of raw coal; Volatile matter is coupled with the combustion process of coke. Due to the influence of volatile matter flame, coal char particles can be ignited below its ignition temperature, and volatile matter has both combustion-promoting and "oxygen-grabbing" effects on coke; The nitrogen oxides produced by partial combustion are related to factors such as reaction temperature, coal quality characteristics, and gas composition;...

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Problems solved by technology

[0003] In order to determine the amount and rate of volatile matter precipitation, thermogravimetric analysis is usually used to test the weight loss and weight loss rate of coal at different heating rates and pyrolysis temperatures; the measurement of pyrolysis components is more complicated and costly; Combining the solution model with experimental data is a more effective research method; in order to predict the composition of coal pyrolysis products, the literature [A predictivemulti-step kinetic model of coal devolatilization[J].Fuel, 2010, 89(2): 318 -328] believed that coal is composed of mixed functional groups that produce specific types of gases with different kinetic parameters, and proposed that during the pyrolysis process, a multi-step kinetic method was used to determine the composition of the pyrolysis products of coal; literature [ Emission of volatile organic compounds from coal combustion[J]. Fuel, 2009, 78(13): 1527-1538] used kinetic and thermodynamic analysis methods to obtain the volatile organic compounds VOCs (Volatile Organic Compounds ) and PAHs (Polynuclear Aromatic Hydrocarbons) and other trace air pollutants formation and emission data; in these methods, the reaction kinetic parameters of each component are used as known data, and these data are not often measured and used in actual production , and the cost of experimental determination of these parameters is relatively high, and the determination of the composition of coal pyrolysis products is greatly affected by the accuracy of these parameters. Therefore, the thermodynamic method has certain defects

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