کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1757052 1523008 2016 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Investigation of methane diffusion in low-rank coals by a multiporous diffusion model
ترجمه فارسی عنوان
بررسی انتشار متان در زغال سنگ های پایین با استفاده از مدل انتشار چندتایی
کلمات کلیدی
انتشار گاز، مدل انتشار چند ضلعی، ساختار پوسته، فشار، محتوای رطوبت
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
چکیده انگلیسی


• A multiporous diffusion model was established to model the diffusion data of low-rank coals.
• The different methane diffusion mechanisms in low-rank coals were analyzed.
• The effects of pressure and moisture on the methane diffusion of low-rank coals were studied.

To study the methane diffusion behaviors of low-rank coals (Ro,m of 0.45% and 0.58%), a combination of CO2 adsorption, N2 adsorption/desorption, and mercury intrusion porosimetry (MIP) measurements were used to characterize the pore structure of coals, and a new multiporous diffusion model was established to model methane diffusion under dry and moist conditions during the methane adsorption process. The results indicate that the pore structure of low-rank coal samples exhibits a multimodal pore size/volume distribution and has a greater percentage of microporosity and mesoporosity. The multiporous model provides a better fit than the bidisperse model, which deviates significantly from the data, especially during the initial diffusion stage. Based on the multiporous diffusion model, the macropore diffusivity (10−4∼10−3 s−1) is generally one to three orders of magnitude greater than the mesopore diffusivity (10−5∼10−4 s−1) and micropore diffusivity (10−6∼10−5 s−1). Moreover, both the macropore diffusivity and micropore diffusivity show a decreasing trend with increasing pressure, whereas a strong positive correlation exists between the mesopore diffusivities and pressure, indicating that the effect of pressure on methane diffusion in pores with different sizes is different during the adsorption process. This difference may be due to the competition between the different mechanisms of gaseous methane diffusion and the swelling of the coal matrix caused by gas adsorption. Furthermore, the moisture-reduced methane diffusivities is mainly due to the moisture in the coal matrix that adsorbs to the pore surface and occupies the pore space, as well as changes the pore structure according to the effect of mineral swelling from the adsorbing moisture. Therefore, these results may have a significant implication for understanding the transport mechanism of methane in coals and the design of enhanced CBM recovery.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Natural Gas Science and Engineering - Volume 33, July 2016, Pages 97–107
نویسندگان
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