2023年全國(guó)碩士研究生考試考研英語(yǔ)一試題真題(含答案詳解+作文范文)_第1頁(yè)
已閱讀1頁(yè),還剩13頁(yè)未讀 繼續(xù)免費(fèi)閱讀

下載本文檔

版權(quán)說明:本文檔由用戶提供并上傳,收益歸屬內(nèi)容提供方,若內(nèi)容存在侵權(quán),請(qǐng)進(jìn)行舉報(bào)或認(rèn)領(lǐng)

文檔簡(jiǎn)介

1、<p><b>  英文原文</b></p><p>  High Productivity —A Question of Shearer Loader Cutting Sequences</p><p>  K. Nienhaus, A. K. Bayer & H. Haut, Aachen University of Technology, GE

2、R</p><p>  1 Abstract</p><p>  Recently, the focus in underground longwall coal mining has been on increasing the installed motor power of shearer loaders and armoured face conveyors (AFC), more

3、 sophisticated support control systems and longer face length, in order to reduce costs and achieve higher productivity. These efforts have resulted in higher output and previously unseen face advance rates. The trend to

4、wards “bigger and better” equipment and layout schemes, however, is rapidly nearing the limitations of technical and </p><p>  2 Introductions</p><p>  Traditionally, in underground longwall min

5、ing operations, shearer loaders produce coal using either one of the following cutting sequences: uni-directional or bi-directional cycles. Besides these pre-dominant methods, alternative mining cycles have also been dev

6、eloped and successfully applied in underground hard coal mines all over the world. The half-web cutting cycle as e.g. utilized in RAG Coal International’s Twentymile Mine in Colorado, USA, and the “Opti-Cycle” of Matla’s

7、 South African sho</p><p>  Whereas the mentioned mines are applying the alternative cutting methods according to their spe-cific conditions, –e.g. seam height or equipment used, –this paper looks systematic

8、ally at the differ-ent methods from a generalised point of view. A detailed description of the mining cycle for each cutting technique, including the illustration of productive and non-productive cycle times, will be fol

9、lowed by a brief presentation of the performed production capacity calculation and a summary of the t</p><p>  3 State-of-the-art of shearer loader cutting sequences</p><p>  The question “Why a

10、re different cutting sequences applied in longwall mining?” has to be an-swered, before discussing the significant characteristics in terms of operational procedures. The major constraints and reasons for or against a sp

11、ecial cutting method are the seam height and hard-ness of the coal, the geotechnical parameters of the coal seam and the geological setting of the mine influencing the caving properties as well as the subsidence and espe

12、cially the length of the longwall face. F</p><p>  A categorization of shearer loader cutting sequences is realised by four major parameters . Firstly, one can separate between mining methods, which mine coa

13、l in two directions – meaning from the head to the tailgate and on the return run as well – or in one direction only. Secondly, the way the mining sequence deals with the situation at the face ends, to advance face line

14、after extract-ing the equivalent of a cutting web, is a characteristic parameter for each separate method. The nec-essary tr</p><p>  Bi-directional cutting sequence</p><p>  The bi-directional

15、cutting sequence, depicted in Figure 1a, is characterised by two sumping opera-tions at the face ends in a complete cycle, which is accomplished during both the forward and return trip. The whole longwall face advances e

16、ach complete cycle at the equivalent of two web distances by the completion of each cycle. The leading drum of the shearer cuts the upper part of the seam while the rear drum cuts the bottom coal and cleans the floor coa

17、l. The main disadvantages of this cutting</p><p>  Uni-directional cutting sequence</p><p>  In contrast to the bi-directional method, the shearer loader cuts the coal in one single direction wh

18、en in uni-directional mode. On the return trip, the floor coal is loaded and the floor itself cleaned. The shearer haulage speeds on the return trips are restricted only by the operators’ movement through the longwall fa

19、ce, or the haulage motors in a fully automated operation. The sumping procedure starts in near the head gate, as shown in Figure 1b. The low machine utilisation because of cutting</p><p>  Half web cutting s

20、equence </p><p>  The main benefit of half web cutting sequences is the reduction of unproductive times in the mining cycle, which results in high machine utilisation. This is achieved by cutting only a half

21、 web in mid face with bi-directional gate sequences as shown in Figure 2a. The full web is mined at the face ends, with lower speeds allowing faster shearer operation in both directions in mid seam. Beside the realisatio

22、n of higher haulage speeds, the coal flow on the AFC is more balanced for shearer loader tr</p><p>  Half-/partial-opening cutting sequence</p><p>  The advantage of the half- or, more precisely

23、, partial- opening cutting sequence is the fact that the face is extracted in two passes. Figure 2b shows that the upper and middle part of the seam is cut during the pass towards the tailgate. Whereas the last part of t

24、his trip for the equivalent of a ma-chine length the leading drum is raised to cut the roof to allow the roof support to be advanced. On the return trip the bottom coal is mined with the advantage of a free face and a sm

25、aller proportio</p><p>  4 Production capacity calculations</p><h2>  A theoretical comparison of the productivity between different mining methods in general, or in this case between different

26、shearer loader cutting cycles, is always based on numerous assumptions and technical and geological restrictions. As a result, this production capacity calculation does not claim to offer exact results, although it does

27、indicate productivity trends and certain parameters for each analysed method. </h2><p>  The model works with so-called height classes varying the seam thicknesses between 2m and 5m in steps of 50cm. Equipme

28、nt is assigned to each class, having been selected by looking at the best-suited technical properties available on the market [4]. Apart from the defined equipment, it is assumed that the seam is flat and no undulations

29、or geological faults occur. In the model, the ventilation and the roof support system represent no restrictions to the production. Since the aim of this model is </p><p>  The variable parameters in this com

30、parison of the four cutting sequences are, (besides seam thick-ness) the specific cutting energy of the coal to be cut and the length of the longwall face. The former varying between 0.2 and 0.4kWh/m³, the latter be

31、tween 100m and 400m in 50m intervals. The 100m shortwalls were deliberately selected, since they are coming more into focus for various reasons. Geotechnical aspects, like e.g. the caving ability of the hanging wall and

32、faults, restrict long-wall pan</p><p>  5 Conclusions </p><p>  In recent years much effort has been put into the optimisation of longwall operations to increase productivity and efficiency. In

33、 many cases the emphasis of these improvements was mainly focused on the equipment, e.g. increased motor power or larger dimensions of AFC’s. The organisational aspect has sometimes been neglected or did not rank as high

34、 on the agenda as other topics. In this paper, it has been demonstrated that the selected mining method has a significant impact on the achievable prod</p><p>  In a theoretical model four cutting sequences

35、have been compared to each other while varying seam thickness, face length and coal properties in terms of specific cutting energy. </p><p>  For each seam or height class a defined set of equipment was used

36、 with consistent restraints. Though each mine is unique, some general conclusions can be drawn analysing the capacity model. Under the restrictions of the model the half web cutting sequence offers the highest output of

37、all analysed methods fol-lowed by the half-opening mode. Depending on the face length, the bi-directional cutting method has advantages compared to the uni-directional sequence in terms of higher productivity. </p>

38、<p><b>  中文譯文</b></p><p>  高效生產(chǎn) —一個(gè)關(guān)于采煤機(jī)截割的次序的問題</p><p><b>  1 摘要</b></p><p>  目前, 地面下長(zhǎng)壁采煤法致力于增加安裝在采煤機(jī)和甲板輸送機(jī)的電機(jī)功率, 以及更先進(jìn)的支架控制系統(tǒng)和增加工作面長(zhǎng)度,以達(dá)到減少費(fèi)用和取得較高的生

39、產(chǎn)效率的目的。這種努力已經(jīng)造成較高的開支和先前未見過的設(shè)備費(fèi)用增長(zhǎng)速度?,F(xiàn)在趨向于 "更大和更好" 的儀器和裝備,然而這種趨勢(shì)在技術(shù)上和費(fèi)用上的可行性已經(jīng)達(dá)到極限。為了要實(shí)現(xiàn)進(jìn)一步促進(jìn)生產(chǎn)力的增加,合理、有機(jī)地規(guī)范長(zhǎng)臂采煤法的工序應(yīng)該是解決提高生產(chǎn)效率問題的唯一的合理答案。在本文中論述了通過合理安排采煤機(jī)的截割次序以實(shí)現(xiàn)提高采煤工作效率。</p><p><b>  2 簡(jiǎn)介<

40、/b></p><p>  傳統(tǒng)上,在地面下長(zhǎng)壁采煤法操作方面,采煤機(jī)挖掘過程中,使用以下截割次序之一:反方向的或雙方向的循環(huán)。除了這兩種主要的方法,交替循環(huán)采煤也已經(jīng)應(yīng)用在地下的硬煤層開采中,它被成功地推廣在全世界的挖掘過程中。就半邊切斷循環(huán)舉例來說,在科羅拉多,美國(guó)在二十里煤礦利用,而且 Matla's 的南非短巷道操作的開采也在這被應(yīng)用。 其他類似的采掘已經(jīng)通過驗(yàn)證改進(jìn)截割次序能提高開采產(chǎn)量,

41、舉例來說,它大約能夠在產(chǎn)量上增加40%的。</p><p>  然而提到應(yīng)用在采煤上根據(jù)特殊情況而改變切割的方法,–用煤層高度和設(shè)備的使用來舉例說明,論文系統(tǒng)地論述通過從不同的角度采取不同的方法。詳細(xì)描述了采礦的每種切割方法, 包括能生產(chǎn)的和不能生產(chǎn)的循環(huán),以下將會(huì)給出一個(gè)簡(jiǎn)短的關(guān)于采煤機(jī)生產(chǎn)能力的計(jì)算和每個(gè)系統(tǒng)在技術(shù)上的受到的約束的概要說明。根據(jù)煤層的厚度采用不同標(biāo)準(zhǔn)的設(shè)備和合適的裝置 。此外采煤機(jī)和甲板輸送機(jī)

42、,工作面的長(zhǎng)度和特定采煤機(jī)截割方式等技術(shù)參數(shù)在本模型中根據(jù)不同的煤層厚度而改變。</p><p>  根據(jù)采煤的產(chǎn)量,不同采煤機(jī)截割的方法可以通過一個(gè)標(biāo)準(zhǔn)化方法繪制產(chǎn)量圖來反映不同截割方法的優(yōu)劣。 根據(jù)模型的特征,最優(yōu)的結(jié)果 ( 通過改變截割方式而得到的不同的采煤產(chǎn)量)就能獲得。 </p><p>  3 采煤截割次序的技術(shù)說明</p><p>  "為什

43、么長(zhǎng)壁采煤法應(yīng)用的不同切割次序?"這個(gè)問題是必須回答的,在以討論操作工序的主要規(guī)則之前,切割方法主要受到煤層的厚度和煤層硬度等因素的限制,就像煤層的物理參數(shù)和礦的地質(zhì)學(xué)條件影響煤的崩落能力一樣,同樣也會(huì)影響長(zhǎng)壁采煤法工作面的煤層塌方。對(duì)于不同的地質(zhì)條件,不同的截割次序都會(huì)得到不同的生產(chǎn)效率和不同質(zhì)量的工作面。 煤送入甲板輸送機(jī)之上正如采煤機(jī)截割,是采煤中的另外一個(gè)問題,尤其是在截齒上受到的屈服應(yīng)力和疲勞應(yīng)力。 一個(gè)對(duì)于選擇最適

44、合的截割次序的全面分析是必要的-適合采礦替換;因?yàn)椋话阈缘慕獯鹗遣荒鼙WC最佳的效率和產(chǎn)量。 </p><p>  對(duì)于一個(gè)采煤機(jī)截割次序的分類是通過四個(gè)主要的參數(shù)來規(guī)定的.第一,能在采礦方法之間分開,向礦井的兩個(gè)方向即從頭到尾。第二,根據(jù)截割次序,在到達(dá)工作面尾部, 預(yù)先在選取一個(gè)等價(jià)的線切斷網(wǎng),是區(qū)分截割方法的一個(gè)獨(dú)立的參數(shù)。必須有一定的距離空間以改變截割次序, 因?yàn)樽鲞@些需要一定的時(shí)間。 定義截割次序的另外

45、一個(gè)方面是網(wǎng)狀斷煤的軌跡。 然而傳統(tǒng)地完整的使用, 現(xiàn)代的甲板輸送機(jī)和液壓支架系統(tǒng)允許使用有效率的一半網(wǎng)方法操作。區(qū)分截割工藝的以前那些參數(shù)就可以把不同的截割方式區(qū)分。除了部份或半開口像被用在Matla的循環(huán)截割中的那些一樣的方法,切斷高度分別包括柔軟懸吊裝置和采煤機(jī)的高度,它和煤層厚度相等。 </p><p><b>  雙方向的截割次序</b></p><p>

46、  在圖1中被描述的雙方向的截割次序, 是表示工作面二點(diǎn)之間的特點(diǎn),在一個(gè)完全的截割操作周期中, 是在兩者的向前和返回期間是完成的。整個(gè)長(zhǎng)壁采煤法每個(gè)周期的完成等價(jià)于在網(wǎng)狀截割軌跡的一個(gè)巡回。滾筒的前端面截割煤層的頂部而滾筒的后端面截割煤層的下部,同時(shí)起到清除落煤的作用。這個(gè)切割的方法主要的缺點(diǎn)主要表現(xiàn)在截割時(shí)間和操作比較復(fù)雜。 因此,趨勢(shì)近幾年來要增加工作面的長(zhǎng)度以減少挖掘過程中的沖擊載荷和延長(zhǎng)截齒的壽命。</p>&l

47、t;p><b>  單方向的截割次序</b></p><p>  與雙方向的方法相反,在單向模型里截割采煤機(jī)截割是朝一個(gè)方向進(jìn)行的。 在回返行程中,地板煤是被采煤機(jī)底板它本身清理。截割運(yùn)動(dòng)在往返時(shí)被在工作面限制了操作運(yùn)動(dòng)推進(jìn)的速度。截割操作在工作面的開頭部位,如圖1 b所示。因?yàn)榍懈顒?dòng)作只能是一個(gè)方向循環(huán)而使截割的工作效率低,它是單向截割次序的主要缺點(diǎn)。此外煤流可能是相當(dāng)不規(guī)則,它依賴

48、于采煤機(jī)在截割周期中的位置。</p><p><b>  半滾筒截割次序</b></p><p>  半滾筒截割的主要優(yōu)點(diǎn)是它減少采煤機(jī)在截割過程中的無(wú)效截割時(shí)間,造成高機(jī)器利用。如圖 2 所顯示的半滾筒截割次序處于工作面中間位置時(shí),它與雙方向截割次序具有一致性。完整的滾筒在截割結(jié)束時(shí),藉由更快速地允許的較低速度在煤層的中間部位向兩個(gè)方向操作。除了實(shí)現(xiàn)較高的牽引速度,

49、在甲板輸送機(jī)被的采煤機(jī)雙向循環(huán)的煤流而平衡。</p><p><b>  半開口切割次序</b></p><p>  這種方法的優(yōu)點(diǎn)更突出,它實(shí)際上是在二個(gè)方法中的提高和改進(jìn)。如圖2 b所示煤層的上端面和中間部分在向它的后端面時(shí)被截割。在回程底部的煤與自由的面和工作面的較小比例的來切斷煤層來一起截割;結(jié)果其牽引速度由于受到材料的切割能特性而限制。滾筒截割在煤層的中間部

50、位不會(huì)產(chǎn)生無(wú)效的截割時(shí)間。類似的回程后門工作面必須在進(jìn)入主工作面之前減小機(jī)身長(zhǎng)度。</p><p><b>  4 生產(chǎn)力計(jì)算</b></p><p>  不同的采礦方法之間的生產(chǎn)力在理論上的做一個(gè)大體的比較, 因?yàn)樵谶@情況通過在不同的之間采煤機(jī)的截割周期,總是存在很多假定和技術(shù)上的以及地質(zhì)學(xué)的限制為基礎(chǔ)。因而,不能提供精確的結(jié)果,但是它為每個(gè)截割方法的分析確實(shí)提供了

51、生產(chǎn)力的高低趨勢(shì)和某些參數(shù)。 </p><p>  該模型實(shí)用于煤層厚度在2 m 和 5 m 之間以50cm為一個(gè)等級(jí)的被稱之為厚煤層的煤礦類型,根據(jù)不同的等級(jí)選擇不同的設(shè)備,可以在市場(chǎng)上選擇最適合該等級(jí)開采的設(shè)備。除了規(guī)范儀器之外,它假設(shè)煤層是平坦的且沒有波動(dòng)和地質(zhì)上的缺陷。在模型中,通風(fēng)和頂層支持系統(tǒng)不對(duì)生產(chǎn)超出限制。 既然這一個(gè)模型的目標(biāo)要實(shí)現(xiàn)進(jìn)一步的增加生產(chǎn)力,該計(jì)算是基于在沒有人工的操作干預(yù)的情況下一個(gè)

52、完全自動(dòng)化的系統(tǒng)操作的工作面。制約牽引速度的唯一因素是甲板輸送機(jī),切割電動(dòng)機(jī)和牽引電動(dòng)機(jī)相互獨(dú)立。 </p><p>  通過比較四種截割次序的可變參數(shù) (除了煤層厚度) 煤截割的能耗和長(zhǎng)壁采煤法的工作面的長(zhǎng)度被降低。前者在0.2 到0.4,后者在100 m 和 400 m 之間每間隔50 m,因?yàn)樗鼈兪艿蕉喾矫娴囊蛩赜绊憽?在地理方面, 像舉例來說墻壁崩落能力和缺陷,它限制煤層最大工作面長(zhǎng)度達(dá)到150 m, 像

53、在南非和英國(guó)。 因?yàn)檫@一個(gè)原因,如此一項(xiàng)詳細(xì)長(zhǎng)壁采煤發(fā)的潛在可行性分析被認(rèn)識(shí)合理的。 </p><p><b>  5 總結(jié)</b></p><p>  近幾年來,很多工作都是致力于長(zhǎng)壁采煤法的最優(yōu)化以增加到生產(chǎn)力和效率的目的。在許多情況,他們過于強(qiáng)調(diào)把重心集中在設(shè)備,舉例來說 增加甲板輸送機(jī)的電動(dòng)機(jī)功率和增大其尺寸。而某些積極的方面有時(shí)被在不同程度上被忽略,它們沒有

54、被提升到一個(gè)比較重要的日程。 在論文中,通過選擇不同的截割次序的采礦方法在生產(chǎn)力上所取得的成功產(chǎn)生深遠(yuǎn)影響。 </p><p>  當(dāng)煤層厚度、工作面長(zhǎng)度、煤層的性質(zhì)以及相關(guān)的截割能耗改變時(shí) ,四中截割模式在一個(gè)理論上可以進(jìn)行相互比較。對(duì)于每種煤層和其厚度等級(jí)的限制而選擇響應(yīng)的設(shè)備。雖然每種截割方式不同,但通過分析該模型可以得到一般性的結(jié)論。根據(jù)模型的約束條件,半滾筒截割的產(chǎn)量最高;在相同的工作面長(zhǎng)度的情況下,雙

溫馨提示

  • 1. 本站所有資源如無(wú)特殊說明,都需要本地電腦安裝OFFICE2007和PDF閱讀器。圖紙軟件為CAD,CAXA,PROE,UG,SolidWorks等.壓縮文件請(qǐng)下載最新的WinRAR軟件解壓。
  • 2. 本站的文檔不包含任何第三方提供的附件圖紙等,如果需要附件,請(qǐng)聯(lián)系上傳者。文件的所有權(quán)益歸上傳用戶所有。
  • 3. 本站RAR壓縮包中若帶圖紙,網(wǎng)頁(yè)內(nèi)容里面會(huì)有圖紙預(yù)覽,若沒有圖紙預(yù)覽就沒有圖紙。
  • 4. 未經(jīng)權(quán)益所有人同意不得將文件中的內(nèi)容挪作商業(yè)或盈利用途。
  • 5. 眾賞文庫(kù)僅提供信息存儲(chǔ)空間,僅對(duì)用戶上傳內(nèi)容的表現(xiàn)方式做保護(hù)處理,對(duì)用戶上傳分享的文檔內(nèi)容本身不做任何修改或編輯,并不能對(duì)任何下載內(nèi)容負(fù)責(zé)。
  • 6. 下載文件中如有侵權(quán)或不適當(dāng)內(nèi)容,請(qǐng)與我們聯(lián)系,我們立即糾正。
  • 7. 本站不保證下載資源的準(zhǔn)確性、安全性和完整性, 同時(shí)也不承擔(dān)用戶因使用這些下載資源對(duì)自己和他人造成任何形式的傷害或損失。

評(píng)論

0/150

提交評(píng)論