Simultaneous thermal analysis on the dynamical oxygen-lean combustion behaviors of coal in a O2/N2/CO2 atmosphere

Su, Haijun; Kang, Ning; Shi, Bobo; Ji, Hongmei; Li, Yunzhuo; Shi, Jingdong

doi:10.1016/j.joei.2021.03.003

Cited by 24 publications

(5 citation statements)

References 28 publications

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“…The increase in the pyrolysis residence time significantly reduced CO emissions and allowed the combustion process to proceed more completely, which resulted in the release of more heat. 28 The pyrolysis process of the sample at a higher temperature would produce more pyrolysis products so that the interaction between the pyrolysis products was enhanced, which contributed to the generation of more CO 2 and methane gas so that the released CO 2 content gradually decreased in the combustion process. 29 Therefore, it was further clarified that increasing the residence time of pyrolysis was beneficial to promoting the reduction of the burnout temperature of char.…”

Section: Results and Analysismentioning

confidence: 99%

“…CO and CO 2 gas layers would gradually form on the surface of the char particles, and the thickness of the surface ash also increased in the later stage of the combustion process, which hindered the diffusion of oxygen into the particles. The increase in the pyrolysis residence time significantly reduced CO emissions and allowed the combustion process to proceed more completely, which resulted in the release of more heat . The pyrolysis process of the sample at a higher temperature would produce more pyrolysis products so that the interaction between the pyrolysis products was enhanced, which contributed to the generation of more CO 2 and methane gas so that the released CO 2 content gradually decreased in the combustion process .…”

Section: Results and Analysismentioning

confidence: 99%

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Study on the Effect of Pyrolysis Conditions on the Combustion Behavior and Char Structure Evolution

et al. 2022

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Pyrolysis polygeneration technology has been widely applied due to its wide adaptability to coal types and mild reaction conditions. In this paper, the in situ process test combining pyrolysis and combustion of Pingshuo coal was carried out using a thermogravimetric analyzer and a fluidized-bed reactor. The influence of pyrolysis conditions on the combustion behavior and char structure was studied. The reduction of the pyrolysis temperature and the increase in pyrolysis residence time resulted in a lower burnout temperature of char, thereby improving the combustion characteristics of char. Furthermore, the maximum CO 2 release rate reached 2.8 mg/(g·s) during the combustion process. The decrease in the pyrolysis temperature was conducive to the increase of CO 2 release mass, suggesting a more complete burning of char. The char combustion process was mainly controlled by the chemical reaction according to the reaction kinetics study. The apparent rate constant of the combustion process increased gradually with the decrease in the pyrolysis temperature of char, and the rate of the combustion reaction increased, which contributed to the enhancement of the combustion performance of the char within the range of 850–950 °C. Meanwhile, the crystal structure inside the char changed significantly after different pyrolysis conditions. However, it had little influence on the molar content of carbon structure, which suggested that the amount of CO 2 released was mainly caused by the different resistances of oxygen diffusion to the reaction interface.

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Section: Results and Analysismentioning

confidence: 99%

Section: Results and Analysismentioning

confidence: 99%

Study on the Effect of Pyrolysis Conditions on the Combustion Behavior and Char Structure Evolution

et al. 2022

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“…At the same time, many scholars have conducted a lot of research on the effect of inert gas on preventing spontaneous combustion of coal. Most of the research focuses on comparing the oxidation characteristics [15][16][17][18][19][20], ignition characteristics [21], combustion characteristics [22], changes in functional groups [23], and the generation of index gases [24] of coal samples in O 2 /N 2 and O 2 /CO 2 atmospheres. These results show that the presence of N 2 and CO 2 is helpful to prevent CSC, and the effect of CO 2 injection is better than that of N 2 .…”

Section: Introductionmentioning

confidence: 99%

Carbon Dioxide Prevents Oxygen Adsorption at Low-Temperature Oxidation Stage of Low-Rank Coal: Laboratory Study and Molecular Simulation

Cheng,

Wang,

Tan

et al. 2023

Processes

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Carbon dioxide (CO2) is widely used in the prevention and control of spontaneous coal combustion. In this manuscript, three low-rank coals with different metamorphic degrees were selected as the research objects. The temperature-programmed experiments, in situ infrared cooling experiments, simulation of the competitive adsorption of CO2 and oxygen (O2) in coal pores, and simulation study of the CO2 inhibition of the coal oxygen composite reaction were used to obtain the role and effect of CO2 in preventing oxygen adsorption in coal at the low-temperature oxidation stage. It was concluded that CO2 can displace the O2 near the pore wall to physically prevent the adsorption of O2. Through the changing law of heating rate and a kinetics analysis, it was found that CO2 can increase its activation energy by 5.3–108.3% during the slow heating stage of coal and reduce its heat rate. At around 120 °C, coal loses the protective effect of CO2. From the changes in functional groups, it can be seen that when coal was cooled in the CO2 atmosphere, mainly pyrolysis and condensation reactions occurred due to the lack of O2. In addition, CO2 can also inhibit the chain reaction of the chemical adsorption of oxygen in coal. This work provides a theoretical basis for CO2 prevention and the control of spontaneous coal combustion.

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“…As a kind of unconventional natural gas resources, coalbed methane (CBM) is mainly composed of a large amount of CH 4 , a small amount of CO 2 , N 2 , H 2 O, and a small amount of other gases. , At present, CBM exploitation has become a hot issue, especially in China where CBM reserves are abundant (about 36.8 trillion m 3 ). − As a clean energy, China has an urgent need for CBM, which can make up for China’s energy shortage problem. , However, the complex storage conditions of CBM in China, the low permeability of coal seams, and the difficulty in mining have caused the contradiction between the growing demand for CBM and the difficulty in energy supply. − …”

Section: Introductionmentioning

confidence: 99%

“…3−5 As a clean energy, China has an urgent need for CBM, which can make up for China's energy shortage problem. 6,7 However, the complex storage conditions of CBM in China, the low permeability of coal seams, and the difficulty in mining have caused the contradiction between the growing demand for CBM and the difficulty in energy supply. 8−10 Coal is a complex material composed of inorganic and organic matter with complex internal structural characteristics.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Strength Damage of Bitumite in Different Freezing States after the Freezing of Liquid Nitrogen at Ultralow Temperature

et al. 2022

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In order to explore the evolution law of mechanical strength of frozen and thawed coal samples after the freezing of liquid nitrogen (LN 2 ) at ultralow temperature, the Yuanzhuang bitumite is cored to make standard samples. The MTS testing machine and ultrasonic detector are used for testing, and the stress−strain curve and ultrasonic time domain image of coal samples are obtained. The evolution law of mechanical strength of coal samples is studied. The results showed that (1) uniaxial compressive strength, elastic modulus, and ultrasonic longitudinal wave velocity of frozen coal samples are positively correlated with the freezing time of LN 2 in 0−50 min and negatively correlated with the freezing time of LN 2 in 50−150 min. (2) The uniaxial compressive strength, elastic modulus, and ultrasonic longitudinal wave velocity of thawed coal samples decrease with the increase of LN 2 freezing time. (3) With the increase of the LN 2 freezing time, the time-domain waveform of coal samples begins to be disordered, and the frequency-domain waveform begins to shift to low peaks, and branch peaks are generated. (4) The brittleness index of frozen coal samples increases with the increase of freezing time, and the brittleness index of thawed coal samples decreases with the increase of freezing time. Compared with the frozen coal samples, the thawed coal samples are subjected to greater thermal stress under the freezing of LN 2 at the same time, which shows a stronger deterioration of mechanical properties. The results can provide a reference for LN 2 fracturing and antireflection.

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Simultaneous thermal analysis on the dynamical oxygen-lean combustion behaviors of coal in a O2/N2/CO2 atmosphere

Cited by 24 publications

References 28 publications

Study on the Effect of Pyrolysis Conditions on the Combustion Behavior and Char Structure Evolution

Study on the Effect of Pyrolysis Conditions on the Combustion Behavior and Char Structure Evolution

Carbon Dioxide Prevents Oxygen Adsorption at Low-Temperature Oxidation Stage of Low-Rank Coal: Laboratory Study and Molecular Simulation

Mechanical Strength Damage of Bitumite in Different Freezing States after the Freezing of Liquid Nitrogen at Ultralow Temperature

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