scholarly journals Study on Calculation Method of Negative Pressure Loss Considering the Deformation of Drainage Borehole

Author(s):  
Xue-Bo Zhang ◽  
Jian-liang Gao
PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242719
Author(s):  
Qingjie Qi ◽  
Xinlei Jia ◽  
Xinhua Zhou ◽  
Youxin Zhao

The internal collapse of deep seam drainage borehole and negative pressure loss represents a serious technical problem affecting gas drainage. To address this problem a creep model of coal around borehole was established based on the plastic softening characteristics of coal. The final collapse time of the borehole was determined and used to derive the three stages of the borehole collapse process. The model of negative pressure loss in drainage borehole was established according to the theory of fluid dynamics, the model of methane gas flow and the creep model of the coal around the borehole. The relationship between the negative pressure loss of drainage and the change of borehole aperture was derived, thereby revealing the main influencing factors of the negative pressure loss in the borehole. A drainage technique named “Full-hole deep screen mesh pipe” was introduced and tested to prevent the collapse of borehole and reduce the negative pressure loss. The result shows that after the borehole was drilled, the borehole wall was affected by the complex stress of the deep coal seam, the coal surrounding the borehole collapsed or presented the characteristics of creep extrusion towards the borehole. The “Full-hole deep screen mesh pipe drainage technology” could effectively control the collapse as well as the deformation of the borehole and reduced the negative pressure loss. Compared with the traditional drainage technology, the methane gas drainage concentration was increased by 101% and the gas flow was increased by 97% when the methane gas was drained for 90 days, the gas drainage efficiency increased significantly.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Weijiu Cui ◽  
Chuankai Zhao ◽  
Sheng Wang

Traditional methods fail to predict the pumping pressure loss of high-performance concrete properly in super high-rise pumping situations due to complex changes of concrete properties. Therefore, it is imperative to propose a relative accurate method for pumping pressure estimation in super high-rise buildings. This paper builds the simplified pressure calculation method “pressure induced by the gravity plus pressure along the pipe line.” The later one is gained by establishing topology optimized model based on computational fluid dynamics and considering the lubrication layer formation. The effect of rheological properties and flow rate is analyzed based on this model in detail. Furthermore, the developed calculation method is verified by the measured pumping pressure during the super high-rise building construction of the Shanghai Tower (the tallest building in China recently). The relative differences between the calculation results and the measured data in situ are less than 6%, indicating the applicability of this method for predicting the pressure loss of the super high-rise pumping.


Author(s):  
A. L. Shuraits ◽  
A. V. Birykov ◽  
A. P. Usachev

Statement of the problem. Currently, there is no methodology for calculating the degree of clogging of a multilayer filter cartridge taking into account the prevention of deposition of mechanical impurities in the gap between the coarse and fine filter cylindrical filter cartridges. In this regard, the development of such a technique is an urgent task. Results. In this paper, we propose a calculation method for determining the average integral degree of clogging of multilayer cylindrical filter cartridges with mechanical impurities and pressure loss on them which take into account the prevention of sedimentation of mechanical impurities in the gap between the coarse and fine filter cartridges.Conclusions. The results obtained make it possible to determine the pressure loss and the average integral degree of clogging of the multilayer filter cartridge depending on the decrease in the living cross-section of all filter meshes in the process of clogging and to prevent the deposition of solids in the gap between the coarse and fine filter cartridges.


Author(s):  
А. Л. Шурайц ◽  
А. В. Бирюков ◽  
А. П. Усачев

Состояние проблемы. В настоящее время отсутствует методика расчета степени засорения многослойного фильтрующего картриджа, учитывающая недопущение осаждения механических примесей в зазоре между цилиндрическими фильтрующими картриджами грубой и тонкой очистки. В этой связи разработка такой методики является актуальной задачей. Результаты. В данной работе предложена методика расчета по определению среднеинтегральной степени засорения многослойных цилиндрических фильтрующих картриджей механическими примесями и потери давления на них, которые учитывают недопущение осаждения механических примесей в зазоре между цилиндрическими фильтрующими картриджами грубой и тонкой очистки. Выводы. Полученные результаты позволяют определить величины потерь давления и среднеинтегральной степени засорения многослойного фильтрующего картриджа в зависимости от величины уменьшения живого сечения всех фильтрующих сеток в процессе их засорения и предотвратить осаждение механических примесей в зазоре между цилиндрическими фильтрующими картриджами грубой и тонкой очистки. Statement of the problem. Currently, there is no methodology for calculating the degree of clogging of a multilayer filter cartridge taking into account the prevention of deposition of mechanical impurities in the gap between the coarse and fine filter cylindrical filter cartridges. In this regard, the development of such a technique is an urgent task. Results. In this paper, we propose a calculation method for determining the average integral degree of clogging of multilayer cylindrical filter cartridges with mechanical impurities and pressure loss on them which take into account the prevention of sedimentation of mechanical impurities in the gap between the coarse and fine filter cartridges. Conclusions. The results obtained make it possible to determine the pressure loss and the average integral degree of clogging of the multilayer filter cartridge depending on the decrease in the living cross-section of all filter grids in the process of clogging and to prevent the deposition of solids in the gap between the coarse and fine filter cartridges. Statement of the problem. Currently, there is no methodology for calculating the degree of clogging of a multilayer filter cartridge taking into account the prevention of deposition of mechanical impurities in the gap between the coarse and fine filter cylindrical filter cartridges. In this regard, the development of such a technique is an urgent task. Results. In this paper, we propose a calculation method for determining the average integral degree of clogging of multilayer cylindrical filter cartridges with mechanical impurities and pressure loss on them which take into account the prevention of sedimentation of mechanical impurities in the gap between the coarse and fine filter cartridges. Conclusions. The results obtained make it possible to determine the pressure loss and the average integral degree of clogging of the multilayer filter cartridge depending on the decrease in the living cross-section of all filter grids in the process of clogging and to prevent the deposition of solids in the gap between the coarse and fine filter cartridges.


1999 ◽  
Vol 3 (1) ◽  
pp. 45-50
Author(s):  
Zbylut J. Twardowski ◽  
Jimmy D. Haynie ◽  
Harold L. Moore
Keyword(s):  

2012 ◽  
Vol 60 (S 01) ◽  
Author(s):  
S Raab ◽  
T Weimann ◽  
W Sienel ◽  
L Lampl ◽  
M Beyer

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