However, the annular fluid field characteristics and cinders transport laws of GDP are not well understood, due to the lack of relevant theoretical research and experimental research. To overcome the above problems, the grooved drill pipe (GDP) possessing coupled cinders removal mechanism (CRM) has been proposed and applied in the soft coal seams. The cinders accumulation and engineering accidents are more likely to occur in the soft coal seam, such as drill pipe sticking (Lu et al., 2010 Li et al., 2020a Li, 2016). However, the cinders in soft coal seam are not able to be effectively removed out of the annulus by the geological drill pipes, due to the low mechanical strength and easy collapse properties of the soft coal seam. Currently, the geological drill pipes, the most common coal mining facilities, have been applied in the coal seam with the reason of their superior hardness and simplicity. Coal plays a dominant role in China's energy structure, and the demand for coal will remain at a high level. ![]() This indicates the performance of cinders transport can be improved by increasing inlet velocity of drilling fluid.Ĭoal, known as the main industrial raw material, plays an important strategic position in the development of manufacturing, thermal power, chemical industries, etc. The volume fraction of residual cinders is dramatically reduced from 0.144 to 0.085 as the inlet velocity increases from 0.6 m/s to 1.2 m/s. A role of guiding and tangential force on fluid field by the helix grooves is found. The results show that the annular velocity and cinders distribution present periodic variations with the drill pipe pitch. Finally, the precision of this model was verified via the experimental data. The annular fluid field characteristics and cinders transport laws of GDP were studied in this model by considering drag force, lift force, and virtual mass force. In this study, the cinders transport model of GDP was developed based on an improved method, combining the kinetic theory of granular flow and Eulerian-Eulerian two-phase flow model. In turning from the texts of other philosophers to his own, Cinders enables readers to follow the trajectory from Derrida’s early work on the trace, the gramma, and the voice to his later writings on life, death, time, and the spectral.Īmong the most accessible of this renowned philosopher’s many writings, Cinders is an evocative and haunting work of poetic self-analysis that deepens our understanding of Derrida’s critical and philosophical vision.Despite the grooved drill pipe (GDP) has been applied in the soft coal seam in recent years, it remains unclear of the cinders transport mechanism in the annulus of GDP. It also contains some of his most essential elaborations of his thinking on the feminine and on the legacy of the Holocaust (both a word-from the Greek hólos, “whole,” and kaustós, “burnt”-and a historical event that invokes ashes) in contemporary poetry and philosophy. In a style that is both highly condensed and elliptical, Cinders offers probing reflections on the relation of language to truth, writing, the voice, and the complex connections between the living and the dead. For Derrida, cinders or ashes-at once fragile and resilient-are “the better paradigm for what I call the trace-something that erases itself totally, radically, while presenting itself.” ![]() In Cinders Derrida ranges across his work from the previous twenty years and discerns a recurrent cluster of arguments and images, all involving in one way or another ashes and cinders. I had to explain myself to it, respond to it-or for it.” It imposed itself upon me with the authority, so discreet and simple it was, of a judgment: ‘cinders there are’ ( il y a là cendre). “More than fifteen years ago,” Jacques Derrida writes in the prologue to this remarkable and uniquely revealing book, “a phrase came to me, as though in spite of me.
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