電磁爐爐盤(pán)運(yùn)輸傳送帶裝置的設(shè)計(jì)含9張CAD圖,電磁爐,盤(pán)運(yùn),傳送帶,裝置,設(shè)計(jì),CAD 附錄A 帶式輸送機(jī)技術(shù)的最新發(fā)展 M. A. AlspaughOverland Conveyor Co., Inc. MINExpo 2004拉斯維加斯, 內(nèi)華達(dá)州，美國(guó) ，9，27, 2004 摘要 粒狀材料運(yùn)輸要求帶式輸送機(jī)具有更遠(yuǎn)的輸送距離、更復(fù)雜的輸送路線和更大的輸送量。為了適應(yīng)社會(huì)的發(fā)展，輸送機(jī)需要在系統(tǒng)設(shè)計(jì)、系統(tǒng)分析、數(shù)值仿真領(lǐng)域向更高層次發(fā)展。傳統(tǒng)水平曲線和現(xiàn)代中間驅(qū)動(dòng)的應(yīng)用改變和擴(kuò)大了帶式輸送機(jī)發(fā)展的可能性。本文回顧了為保證輸送機(jī)的可靠性和可用性而運(yùn)用數(shù)字工具的一些復(fù)雜帶式輸送機(jī)。 前言 雖然這篇文章的標(biāo)題表明在皮帶輸送機(jī)技術(shù)中將提出“新”發(fā)展，但是提到的大多思想和方法都已存在很長(zhǎng)時(shí)間了。 我們不懷疑被提出一些部件或想法將是“新”的對(duì)你們大部分人來(lái)說(shuō)。所謂的“新”就是利用成熟的技術(shù)和部件組成特別的、復(fù)雜的系統(tǒng)； “新”就是利用系統(tǒng)設(shè)計(jì)工具和方法，匯集一些部件組成獨(dú)特的輸送機(jī)系統(tǒng)，并解決大量粒狀原料的裝卸問(wèn)題；“新”就是在第一次系統(tǒng)試驗(yàn)(委任)之前利用日益成熟的計(jì)算機(jī)技術(shù)進(jìn)行準(zhǔn)確節(jié)能計(jì)算機(jī)模擬。 同樣，本文的重點(diǎn)是特定復(fù)雜系統(tǒng)設(shè)計(jì)及滿足長(zhǎng)距離輸送的要求。 這四個(gè)具體課題將覆蓋： l 托輥?zhàn)枇? l 節(jié)能 l 動(dòng)力分散 l 分析與仿真 節(jié)能 減小設(shè)備整體電力消費(fèi)是所有項(xiàng)目的一個(gè)重要方面，皮帶輸送機(jī)是也不例外。 雖然與其他運(yùn)輸方法比較皮帶輸送機(jī)總是運(yùn)輸大噸位高效率的手段，但是減少帶式輸送機(jī)的功率消耗的方法還是很多的。 皮帶輸送機(jī)的主要阻力組成部分有： l 托輥?zhàn)枇? l 托輥與皮帶的摩擦力 l 材料或輸送帶彎曲下垂引起的阻力 l 重力 這些阻力加上一些混雜阻力組成輸送材料所需的力。1 在一臺(tái)輸送長(zhǎng)度400米的典型短距離輸送機(jī)中,力可以分為如圖1所示的幾個(gè)部分，圖中可以看出提升力所占比例最大，而阻力還是占絕大部分。 圖1 在高傾斜輸送帶中如礦用露天傾斜輸送帶，所受力可分解為圖2所示的幾個(gè)部分，其中提升力仍占巨大比例。由于重力是無(wú)法避免的，因此沒(méi)有好的方法減少傾斜式輸送機(jī)所受力。 圖 2 但是在長(zhǎng)距離陸上輸送機(jī)中，所受力更趨向圖3所示的幾個(gè)部分，不難看出摩擦力幾乎是所受力的全部。這種情況下考慮主要受力才是最重要的。 圖 3 力量演算具體是超出本文的范圍之外，但是值得一提的是，在過(guò)去幾年對(duì)所有四個(gè)區(qū)域橡膠凹進(jìn)、對(duì)準(zhǔn)線和材料或者傳送帶彎曲等方面的重要研究都在進(jìn)行。 并且，雖然在處理每特定區(qū)域時(shí)大家有不同意見(jiàn)，通常對(duì)整體項(xiàng)目經(jīng)濟(jì)是必要和重要的是被大家被接受的。 在2004個(gè)SME年會(huì)上，MAN Takraf的Walter Kung介紹了題為“Henderson粗糙礦石輸送系統(tǒng)—回顧組裝、起動(dòng)和操作”2。 這個(gè)項(xiàng)目在1999年12月被實(shí)施并且包括一個(gè)24公里(3飛行)陸上轉(zhuǎn)達(dá)的系統(tǒng)替換地下礦碾碎路軌貨車使用系統(tǒng)。 圖4 - Henderson PC2到PC3調(diào)動(dòng)站 最長(zhǎng)的傳動(dòng)機(jī)在這個(gè)系統(tǒng)(PC2)是16.28公里長(zhǎng)與475m升距。最重要的系統(tǒng)事實(shí)是提供的功率(4000千瓦在1783 mtph 和4.6 m/s)的50% 被要求用來(lái)轉(zhuǎn)動(dòng)一條空載的帶子，因此輸送系統(tǒng)的效率是很重要的。需密切注意托輥、傳送帶蓋子橡膠和對(duì)準(zhǔn)線。用文件說(shuō)明有關(guān)的效率的差別是的一種方法， 使用"相等的摩擦系數(shù)f"的22101標(biāo)準(zhǔn)定義作為比較主要抵抗的總數(shù)的另一種方法。過(guò)去，象這樣典型輸送裝置的綜合設(shè)計(jì)噪音系數(shù)大約是0.016f。MAN Takraf正估計(jì)他們對(duì)力的敏感達(dá)到到0.011的f，超過(guò)30%的削減。這在減少設(shè)備建造成本上做出了重大貢獻(xiàn)。通過(guò)六次的實(shí)際動(dòng)態(tài)測(cè)量顯示價(jià)值是0.0075，甚至比期望值低30%。 Kung先生強(qiáng)調(diào)這將在僅僅用電費(fèi)用一項(xiàng)上每年減少費(fèi)用10萬(wàn)美元。 線路優(yōu)化 圖5 – 中國(guó)天津 水平適應(yīng)性 當(dāng)然最高效率的材料運(yùn)輸方式是從一點(diǎn)到下一點(diǎn)的直線輸送。 但是，由于自然和認(rèn)為障礙的存在，我們?cè)陂L(zhǎng)距離輸送過(guò)程中直接直線輸送的可能性越來(lái)越小。第一臺(tái)水平彎曲輸送機(jī)已在很多年前安裝使用，但它今天似乎關(guān)于安裝的每臺(tái)陸上傳動(dòng)機(jī)在方向至少有一個(gè)水平變化。并且今天的技術(shù)允許設(shè)計(jì)師相對(duì)地容易地調(diào)整這些曲線。 圖5和圖6顯示的是把煤從蘊(yùn)藏地運(yùn)輸?shù)街袊?guó)天津港口管理處的陸上輸送裝置。這套運(yùn)輸機(jī)由E.J. O’Donovan & Associates設(shè)計(jì)，由 Continental Conveyor Ltd of Australia 公司承建，長(zhǎng)達(dá)9千米的輸送距離4臺(tái)1500千萬(wàn)電機(jī)驅(qū)動(dòng)運(yùn)輸能力達(dá)6000 mtph 。 圖6 – 天津輸送線平面圖 Wyodak礦位于美國(guó)懷俄明州粉河流域，是記錄中最古老的連續(xù)經(jīng)營(yíng)的煤礦，自1923年運(yùn)營(yíng)至今。它一般運(yùn)用坡面(圖7)從新的礦坑到裝置756m (2,482 ft)與700m (2,300 ft)水平的半徑。 這表明由于水平輪的應(yīng)用輸送機(jī)不需要設(shè)計(jì)太長(zhǎng)3。 圖7- Wyodak 煤礦 隧道式 如通過(guò)沒(méi)有水平曲線線路，另一項(xiàng)產(chǎn)業(yè)，隧道挖掘，就不能使用帶式輸送機(jī)了。 隧道就想象廢水和運(yùn)輸那樣的基礎(chǔ)設(shè)施在全世界有。 移動(dòng)隧道糞肥的最有效率的方法通過(guò)把推進(jìn)的輸送裝置和隧道機(jī)器的后部連結(jié)起來(lái)。但是這些隧道極少是直的。 這里有一個(gè)例子，西班牙10.9m直徑隧道的在巴塞羅那之下作為地鐵(火車)引伸項(xiàng)目一部分。大陸輸送機(jī)機(jī)有限公司安裝了前4.7km傳動(dòng)機(jī)如圖8和9所顯示和最近接受合同安裝第二臺(tái)8.39公里輸送機(jī)。 圖 8- 巴塞羅那隧道平面圖 圖 9- 隧道內(nèi)部 另一個(gè)例子， 肯珀建設(shè)邊境時(shí)，建設(shè)一個(gè)直徑3.6米長(zhǎng)6.18公里的隧道作為大都市圣路易斯的下水道區(qū)。鮑姆加特納隧道(圖10)將裝有600毫米寬的用4個(gè)中間運(yùn)動(dòng)用帶子系住的6.1 公里輸送裝置。 圖10- 鮑姆加特納隧道平面圖 管狀輸送裝置 如果常規(guī)輸送機(jī)不能滿足必須的輸送要求，帶式輸送機(jī)的一種管狀輸送機(jī)會(huì)是不錯(cuò)的選擇。 圖 11- 管狀輸送裝置 它最簡(jiǎn)單的描述，管狀輸送機(jī)就是由管狀橡膠管和空轉(zhuǎn)輥組成。這種設(shè)計(jì)具有其他傳送方式的優(yōu)點(diǎn)，更有自己的特點(diǎn)。 托輥可以在各個(gè)方向傳力允許更復(fù)雜的曲線輸送。這些曲線可以是水平或垂直或混合形式。這樣的輸送機(jī)輸送帶與托輥之間的重力和摩擦力保證原料在輸送管道內(nèi)。 Figure 12 管狀輸送機(jī)的另一個(gè)好處可以輸送粉狀原料并且可以減少溢出浪費(fèi)，因?yàn)椴牧鲜窃诠艿纼?nèi)部。一個(gè)典型的例子是環(huán)境效益和適應(yīng)性特好的美國(guó)猶他州地平線礦（圖12）。這個(gè)長(zhǎng)3.38公里的管狀輸送機(jī)由ThyssenKrupp Robins 安裝通過(guò)一個(gè)國(guó)家森林并且橫斷了22個(gè)水平段和45個(gè)垂直段。 Metso 繩索輸送機(jī) 另一種由常規(guī)衍變來(lái)的是Mesto 繩索輸送機(jī)（MRC），通常以纜繩傳送帶著名。這個(gè)產(chǎn)品以長(zhǎng)途輸送著名，在距澳大利亞30.4公里的沃斯利鋁土礦上應(yīng)用的輸送帶是最長(zhǎng)的單個(gè)飛行輸送機(jī)。在鋼繩輸送機(jī)上，驅(qū)動(dòng)裝置和運(yùn)載媒介是分離的。 圖13 - MRC-平直的部分 這種驅(qū)動(dòng)與輸送裝置的分離允許輸送有小半徑的水平彎曲，這種設(shè)計(jì)優(yōu)于根 距張緊力和地勢(shì)的傳統(tǒng)設(shè)計(jì)。 圖 14 MRC與常規(guī)輸送機(jī)水平曲線的不同 圖 15- 位于加拿大 Line Creek的MRC 圖15顯示的是位于加拿大Line Creek河畔的一條長(zhǎng)10.4公里水平半徑430米的纜繩輸送帶 立式輸送裝置 有時(shí)材料需要被提升或下降而常規(guī)輸送機(jī)被限制在16—18度附近的傾斜角度內(nèi)。但是帶式輸送機(jī)的非傳統(tǒng)衍變不管是在增加角度還是平直方面都是相當(dāng)成功的。 大角度輸送機(jī) 第一臺(tái)大角度輸送機(jī)由Continental Conveyor & Equipment Co.公司生產(chǎn)，非常利用常規(guī)輸送機(jī)零部件（圖16）構(gòu)成。當(dāng)原料在兩條帶子之間輸送時(shí)，被稱為三明治輸送裝置。 圖16 Continental 公司的第100套大傾角輸送裝置采用獨(dú)特的可平移式設(shè)計(jì)，作為Mexican de Canenea的堆過(guò)濾墊（圖17）。 Figure 17 垂直式輸送裝置 第二種立式輸送裝置展現(xiàn)的是一種非常規(guī)的帶式裝置，它可以實(shí)現(xiàn)垂直輸送（圖18）。 這種Mesto 垂直輸送機(jī)，2001年由Frontier Kemper 安裝在白縣煤礦Pattiki 2礦（圖19），將煤由273米深的礦井輸出并達(dá)到1,818 mtph的輸送能力。 圖18 圖19- Pattiki 2礦 動(dòng)力分散 在最近過(guò)去的一段時(shí)間里，一種最有趣的發(fā)展是電力沿輸送道路的分配?？吹捷斔蜋C(jī)驅(qū)動(dòng)裝置安裝在收尾末端，讓尾端驅(qū)動(dòng)完成輸送帶的拉緊輸送工作。但是現(xiàn)在的發(fā)展觀念是把驅(qū)動(dòng)安裝在任何需要的位置。 在帶式輸送機(jī)上多個(gè)位置安裝動(dòng)力源的想法已經(jīng)存在很長(zhǎng)一段時(shí)間了。第一次應(yīng)用是1974年安裝在美國(guó)Kaiser煤礦。緊接著是在地下煤礦中得到應(yīng)用，而且長(zhǎng)臂開(kāi)采法也越來(lái)越體現(xiàn)它的優(yōu)越性。采礦設(shè)備的效率和能力也得到巨大改善。礦工們也開(kāi)始尋找大的礦區(qū)從而減少移動(dòng)大型采礦設(shè)備的次數(shù)及時(shí)間。礦井寬度和礦井分格長(zhǎng)度都得到增加。 當(dāng)?shù)V井分格長(zhǎng)度增加后，輸送問(wèn)題開(kāi)始出現(xiàn)。接近4-5千米的輸送長(zhǎng)度所需要的電力和輸送帶的強(qiáng)度比以前地下煤礦需要的大很多。問(wèn)題是大號(hào)的高電力驅(qū)動(dòng)裝置安裝及移動(dòng)困難。雖然膠帶技術(shù)能夠滿足膠帶所需強(qiáng)度要求，它意味著需要比鋼鐵更重要的強(qiáng)度及加硫處理。由于長(zhǎng)臂開(kāi)采法的盤(pán)區(qū)傳動(dòng)機(jī)經(jīng)常推進(jìn)和后退，礦工需要經(jīng)常增加或取消滾筒的正傳與逆轉(zhuǎn)。而且硫化結(jié)合需要長(zhǎng)期維護(hù)以保證強(qiáng)度，因而失去的產(chǎn)品生產(chǎn)時(shí)間在一個(gè)完全盤(pán)區(qū)中是很嚴(yán)重的。現(xiàn)在需要超過(guò)風(fēng)險(xiǎn)，并且中間驅(qū)動(dòng)的應(yīng)用限制了輸送帶的伸長(zhǎng)及張緊這樣就允許纖維膠帶在長(zhǎng)距離輸送機(jī)中應(yīng)用。 現(xiàn)今，中間驅(qū)動(dòng)技術(shù)被很好的接受并越來(lái)越廣泛的應(yīng)用于地下煤礦中。世界范圍內(nèi)的許多礦把這項(xiàng)技術(shù)整合到現(xiàn)在和未來(lái)礦業(yè)計(jì)劃當(dāng)中來(lái)增加他們的整體采礦效率和效益6。 表20所示的張緊圖顯示了中間驅(qū)動(dòng)的重大好處。這種平面前驅(qū)的輸送機(jī)有簡(jiǎn)單的皮帶張力分布如黑色線條所示。雖然平均皮帶張力在每個(gè)周期期間只約為最大值的40%，但必須圍繞最大估量值附近。黑色線條的急劇回落表示頂頭滑輪要求的總扭矩和力量來(lái)啟動(dòng)輸送機(jī)。 將受力分解到兩個(gè)地點(diǎn)（紅線），當(dāng)總功率基本相同的情況下，皮帶張力差不多減少40%。因此更小的輸送帶和更小的電源組可以得到運(yùn)用。為了進(jìn)一步擴(kuò)展這種方式，增加第二中間驅(qū)動(dòng)（綠線），皮帶峰頂張力進(jìn)一步下降。 隧道產(chǎn)業(yè)也迅速采用這種技術(shù)并且把這項(xiàng)技術(shù)提高到更好的水平，更復(fù)雜更先進(jìn)。但挖隧道最需要的是水平曲線的進(jìn)步。 通過(guò)中間驅(qū)動(dòng)（圖21）的一種應(yīng)用例如Baumgartner 隧道如前圖10所描述，皮帶張緊力可以通過(guò)在重要的地點(diǎn)安裝戰(zhàn)略驅(qū)動(dòng)來(lái)控制，從而實(shí)現(xiàn)輸送帶的小曲線換向。 圖20 圖21 在圖22中，綠色投影區(qū)域代表彎曲結(jié)構(gòu)的地點(diǎn)。藍(lán)色線條代表輸送帶運(yùn)載面，粉紅色線條代表輸送帶返回面?？梢园l(fā)現(xiàn)在彎曲半徑最小750米時(shí)輸送帶運(yùn)載面和返回面所受張緊力均達(dá)到最小。 圖22 盡管到目前為止，這項(xiàng)技術(shù)陸上輸送機(jī)中沒(méi)有廣泛的應(yīng)用，一些傾向于水平曲線的技術(shù)卻得到發(fā)展。圖23顯示了南美洲的一條長(zhǎng)8.5千米硬巖層輸送帶，它需要4個(gè)中間驅(qū)動(dòng)來(lái)實(shí)現(xiàn)4段2000米半徑的曲線轉(zhuǎn)向。 Figure 23- 平面圖 圖24顯示在彎曲段有與沒(méi)有驅(qū)動(dòng)時(shí)輸送帶的張緊力比較。 分散驅(qū)動(dòng)的優(yōu)點(diǎn)在MRC纜繩輸送帶中也得到應(yīng)用。然而張緊運(yùn)載的繩索有別于負(fù)載傳送帶，安裝中間驅(qū)動(dòng)更加容易，輸送的原料不用離開(kāi)運(yùn)載輸送帶的表面。張緊運(yùn)載的繩索與輸送帶分開(kāi)足夠的距離，便利在安裝中間驅(qū)動(dòng)后繼續(xù)工作。(圖25). 圖24- 張緊曲線 圖25 分析與仿真 許多人在爭(zhēng)論我們建造以上描述的復(fù)雜輸送機(jī)的能力時(shí)，歸因于許多分析和仿真工具的發(fā)展。組件制造商可以通過(guò)測(cè)試他的產(chǎn)品以保證符合規(guī)格；然而系統(tǒng)工程師很少能測(cè)試完成的系統(tǒng)，知道它在站點(diǎn)完成。所以計(jì)算方法和工具在模仿各種各樣不同學(xué)科和組分上的作用是絕對(duì)重要的。 動(dòng)態(tài)開(kāi)始和停止 當(dāng)進(jìn)行開(kāi)始和停止試驗(yàn)時(shí)，假設(shè)所有的質(zhì)量單元同時(shí)加速；也就是把輸送帶看做一個(gè)剛體（非彈性體）。實(shí)際上，推進(jìn)扭矩通過(guò)滑輪產(chǎn)生的壓力波傳遞給輸送帶，并通過(guò)壓力波的傳播帶動(dòng)輸送帶運(yùn)行。壓力在輸送帶上傳播時(shí)發(fā)生由阻礙輸送帶運(yùn)行的阻抗產(chǎn)生的縱波引起的變化。7 從1959開(kāi)始許多出版物都指出彈性輸送帶的大輸送量、長(zhǎng)距離輸送機(jī)在停止和啟動(dòng)時(shí)會(huì)導(dǎo)致傳動(dòng)裝置、驅(qū)動(dòng)裝置、張緊裝置的選擇等錯(cuò)誤。對(duì)彈性瞬變響應(yīng)的疏忽可能導(dǎo)致不精確的后果： l 輸送帶最大壓力 l 滑輪上的最大壓力 l 輸送帶的最小壓力及原料泄漏 l 提升壓力要求 l 提升行程和速度要求 l 驅(qū)動(dòng)輪 l 啟動(dòng)轉(zhuǎn)矩 l 制動(dòng)轉(zhuǎn)矩 l 各驅(qū)動(dòng)間的負(fù)載分擔(dān) l 原料在斜面上的穩(wěn)定性 為了長(zhǎng)期應(yīng)用，通過(guò)數(shù)學(xué)模型對(duì)彈性輸送帶在開(kāi)始和停止時(shí)的狀態(tài)進(jìn)行模擬是非常重要的。 一部完整輸送機(jī)系統(tǒng)的模型可通過(guò)劃分輸送機(jī)為一系列的有限元素來(lái)實(shí)現(xiàn)。每個(gè)元素由一個(gè)質(zhì)量和一個(gè)流變彈簧組成，如圖26所示。 圖 26 許多分析輸送帶無(wú)力性能的方法都在研究，如把它看做一個(gè)流變彈簧，而且大量的技術(shù)也被用來(lái)這方面的研究。一個(gè)合適的模型需要包含以下幾個(gè)方面： 1. 傳送帶縱向拉伸量的彈性模數(shù) 2. 對(duì)從屬運(yùn)動(dòng)的阻抗 3. 凹陷處的粘彈性損失 4. 由于輸送帶的下垂引起的輸送帶模數(shù)變動(dòng) 因?yàn)榧償?shù)學(xué)解決這些動(dòng)態(tài)問(wèn)題是非常復(fù)雜的，它的目標(biāo)不是詳述基礎(chǔ)的動(dòng)態(tài)理論分析。相反，它的目的是讓長(zhǎng)距離輸送、水平彎曲、分散驅(qū)動(dòng)在輸送機(jī)上更普遍，對(duì)傳送帶停止和開(kāi)始進(jìn)行彈性動(dòng)態(tài)分析的重要性是開(kāi)發(fā)適當(dāng)?shù)目刂扑惴ā? 以圖23 8.5千米輸送機(jī)為例，兩個(gè)虛擬開(kāi)始被模擬來(lái)比較它們的控制算法。一種是兩個(gè)1000千瓦的驅(qū)動(dòng)安裝在頭部尾端，二個(gè)1000千瓦驅(qū)動(dòng)安裝在輸送面的中點(diǎn)，另一個(gè)1000千瓦驅(qū)動(dòng)安裝在尾部，要極端小心保證所有驅(qū)動(dòng)的協(xié)調(diào)與維護(hù)。 圖27顯示一個(gè)不協(xié)調(diào)并嚴(yán)重?cái)[動(dòng)輸送機(jī)120秒啟動(dòng)的扭矩圖及其相應(yīng)的速度輸送帶擺動(dòng)圖。T1/T2滑動(dòng)比率表明推進(jìn)滑動(dòng)可能發(fā)生。圖28顯示對(duì)應(yīng)的一個(gè)180秒啟動(dòng)圖，并能夠安全和順利的加速輸送機(jī)。 圖27-120 秒惡劣啟動(dòng) 圖 28- 180 良好啟動(dòng) 轉(zhuǎn)運(yùn)站的質(zhì)流 運(yùn)用中間驅(qū)動(dòng)和鏈板輸送能長(zhǎng)期使用的一個(gè)原因就是消除轉(zhuǎn)運(yùn)站。許多最困難的問(wèn)題在帶式輸送機(jī)裝貨和卸載附近集中。傳送溜槽通常選在輸送機(jī)高效維護(hù)區(qū)域，同時(shí)重大生產(chǎn)風(fēng)險(xiǎn)在這里集中。 l 堵塞 l 輸送帶和滑道損傷和磨蝕物質(zhì)退化 l 粉塵 l 裝貨/溢出偏心 過(guò)去，沒(méi)有分析工具，反復(fù)試驗(yàn)和經(jīng)驗(yàn)是設(shè)計(jì)工程師唯一可用的設(shè)計(jì)方法；現(xiàn)在，數(shù)值仿真方法的存在允許設(shè)計(jì)師在制造之前測(cè)試他們的設(shè)計(jì)。 數(shù)字仿真是根據(jù)一個(gè)實(shí)際的物理系統(tǒng)設(shè)計(jì)的模型，并在計(jì)算機(jī)上模擬和分析結(jié)果。仿真體現(xiàn)在實(shí)踐中學(xué)習(xí)的精神。為了了解現(xiàn)實(shí)及其復(fù)雜性，我們?cè)谟?jì)算機(jī)上建立虛擬物體并動(dòng)態(tài)的觀察它們間的相互作用。 分離元素法是解決工程學(xué)和應(yīng)用科學(xué)如粒狀材料流等不連續(xù)的機(jī)械行為問(wèn)題的一種數(shù)字模擬技術(shù)。值得注意的是，由非連續(xù)行為引起的行為不能依靠傳統(tǒng)基基于計(jì)算機(jī)的連續(xù)流塑造方法例如有限元素分析、有限差規(guī)程和甚而計(jì)算流體動(dòng)力學(xué)(CFD)的來(lái)進(jìn)行模擬。 DEM系統(tǒng)模仿每個(gè)部件或微粒的動(dòng)態(tài)行為和機(jī)械互作用，并提供分析期間每個(gè)部件和微粒的位置、速度、和力量的詳細(xì)描述。8 在分析過(guò)程中，微粒被塑造成有形狀的物體，這些物體之間及于界限表面、運(yùn)載表面互相作用，這些物體接觸和碰撞形成他們之間法向、切向力. 正常接觸分力在碰撞過(guò)程中引起一個(gè)線性有彈性恢復(fù)的組分和一個(gè)粘阻力來(lái)模擬能量損失。線性有彈性組分系數(shù)根據(jù)自身屬性確定，正常粘滯系數(shù)可以根據(jù)一個(gè)等效恢復(fù)系數(shù)的彈簧來(lái)塑造（圖29）。 圖29 圖30顯示顆粒下落通過(guò)傳送帶溜槽。圖示中顆粒的顏色代表他們的速度。紅色代表零速度，而綠色代表最高速度。也許這些工具的最大好處就是一位老練的工程師能通過(guò)形象化表示設(shè)計(jì)施工前有個(gè)行像的表現(xiàn)。有了這個(gè)形象的感覺(jué)在施工過(guò)程中可以盡量減少不必要的工作。 其他定量數(shù)據(jù)也可能被隱藏包括在輸送帶或滑道墻壁的沖擊和剪切力。 圖30 前景 更大的帶式輸送機(jī) 本文提到了一臺(tái)最長(zhǎng)的唯一飛行常規(guī)輸送機(jī)，長(zhǎng)16.26公里的Henderson PC2。但一臺(tái)19.1公里的輸送機(jī)在美國(guó)正在建設(shè)中，并且一臺(tái)23.5公里的飛行式輸送機(jī)在澳洲被設(shè)計(jì)。其他長(zhǎng)30-40公里的輸送機(jī)在世界其他地區(qū)討論研究。 當(dāng)定量凹進(jìn)的方式為人所知，輸送帶制造商開(kāi)發(fā)了低輾壓抗壓儲(chǔ)力10-15%的橡膠輸送帶。與改進(jìn)的設(shè)施方法和對(duì)準(zhǔn)線一起作用，節(jié)能是可以實(shí)現(xiàn)的。 地下煤礦和隧道承包商將繼續(xù)使用已經(jīng)證明對(duì)他們有好處的分散驅(qū)動(dòng)方式；至少有兩種在表面輸送機(jī)中安裝中間驅(qū)動(dòng)的輸送機(jī)在2005年運(yùn)行。 在德國(guó)，RWE Rheinbraun 使煤礦用輸送機(jī)輸送量達(dá)到30,000 tph ，并且其他表面煤礦也在有計(jì)劃的接近這個(gè)輸送量。隨著輸送兩的增加，輸送帶的速度也在增加，這樣就要求更好的設(shè)備、工藝公差、阻力和動(dòng)力分析。 我們希望輸送機(jī)能夠更遠(yuǎn)、更寬、更高、更快，采用所有分析工具來(lái)分析系統(tǒng)性能。因?yàn)槊颗_(tái)輸送機(jī)都是獨(dú)特的，我們唯一的預(yù)見(jiàn)方式就是外面的數(shù)據(jù)分析和模仿工具。因此由于外面的目標(biāo)越來(lái)越大，我們有必要改進(jìn)設(shè)計(jì)工具。 附錄B Latest Developments in Belt Conveyor Technology M. A. Alspaugh Overland Conveyor Co., Inc. Presented at MINExpo 2004Las Vegas, NV, USA September 27, 2004 Abstract Bulk material transportation requirements have continued to press the belt conveyor industry to carry higher tonnages over longer distances and more diverse routes. In order keep up, significant technology advances have been required in the field of system design, analysis and numerical simulation. The application of traditional components in non-traditional applications requiring horizontal curves and intermediate drives have changed and expanded belt conveyor possibilities. Examples of complex conveying applications along with the numerical tools required to insure reliability and availability will be reviewed. Introduction Although the title of this presentation indicates “new” developments in belt conveyor technology will be presented, most of the ideas and methods offered here have been around for some time. We doubt any single piece of equipment or idea presented will be “new” to many of you. What is “new” are the significant and complex systems being built with mostly mature components. What is also “new” are the system design tools and methods used to put these components together into unique conveyance systems designed to solve ever expanding bulk material handling needs. And what is also “new” is the increasing ability to produce accurate Energy Efficiency computer simulations of system performance prior to the first system test (commissioning). As such, the main focus of this presentation will be the latest developments in complex system design essential to properly engineer and optimize today’s long distance conveyance requirements. The four specific topics covered will be: l Idler Resistance l Energy Efficiency l Distributed Power l Analysis and Simulation Energy Efficiency Minimizing overall power consumption is a critical aspect of any project and belt conveyors are no different. Although belt conveyors have always been an efficient means of transporting large tonnages as compared to other transport methods, there are still various methods to reduce power requirements on overland conveyors. The main resistances of a belt conveyor are made up of: l Idler Resistance l Rubber indentation due to idler support l Material/Belt flexure due to sag being idlers l Alignment These resistances plus miscellaneous secondary resistances and forces to over come gravity (lift) make up the required power to move the material.1 In a typical in-plant conveyor of 400m length, power might be broken into its components as per Figure 1 with lift making up the largest single component but all friction forces making up the majority. Figure 1 In a high incline conveyor such as an underground mine slope belt, power might be broken down as per Figure 2, with lift contributing a huge majority. Since there is no way to reduce gravity forces, there are no means to significantly reduce power on high incline belts. Figure 2 But in a long overland conveyor, power components will look much more like Figure 3, with frictional components making up almost all the power. In this case, attention to the main resistances is essential. Figure 3 The specifics of power calculation is beyond the scope of this paper but it is important to note that significant research has been done on all four areas of idlers, rubber indentation, alignment and material/belt flexure over the last few years. And although not everyone is in agreement as to how to handle each specific area, it is generally well accepted that attention to these main resistances is necessary and important to overall project economics. At the 2004 SME annual meeting, Walter Kung of MAN Takraf presented a paper titled “The Henderson Coarse Ore Conveying System- A Review of Commissioning, Start-up and Operation”2. This project was commissioned in December 1999 and consisted of a 24 km (3 flight) overland conveying system to replace the underground mine to mill rail haulage system. Figure 4- Henderson PC2 to PC3 Transfer House The longest conveyor in this system (PC2) was 16.28 km in length with 475m of lift. The most important system fact was that 50% of the operating power (~4000 kW at 1783 mtph and 4.6 m/s) was required to turn an empty belt therefore power efficiency was critical. Very close attention was focused on the idlers, belt cover rubber and alignment. One way to document relative differences in efficiency is to use the DIN 22101 standard definition of “equivalent friction factor- f” as a way to compare the total of the main resistances. In the past, a typical DIN fused for design of a conveyor like this might be around 0.016. MAN Takraf was estimating their attention to power would allow them to realize an f of 0.011, a reduction of over 30%. This reduction contributed a significant saving in capital cost of the equipment. The actual measured results over 6 operating shifts after commissioning showed the value to be 0.0075, or even 30% lower than expected. Mr. Kung stated this reduction from expected to result in an additional US$100, 000 savings per year in electricity costs alone. Route Optimization Figure 5- Tiangin China Horizontal Adaptability Of course the most efficient way to transport material from one point to the next is as directly as possible. But as we continue to transport longer distances by conveyor, the possibility of conveying in a straight line is less and less likely as many natural and man-made obstacles exist. The first horizontally curved conveyors were installed many years ago, but today it seems just about every overland conveyor being installed has at least one horizontal change in direction. And today’s technology allows designers to accommodate these curves relatively easily. Figures 5 and 6 shows an overland conveyor transporting coal from the stockpile to the shiploader at the Tianjin China Port Authority installed this year. Designed by E.J. O’Donovan & Associates and built by Continental Conveyor Ltd of Australia, this 9 km overland carries 6000 mtph with 4x1500 kW drives installed. Figure 6- Tiangin China Plan View The Wyodak Mine, located in the Powder River Basin of Wyoming, USA, is the oldest continuously operating coal mine in the US having recorded annual production since 1923. It currently utilizes an overland (Figure 7) from the new pit to the plant 756m long (2,482 ft) with a 700m (2,300 ft) horizontal radius. This proves a conveyor does not need to be extremely long to benefit from a horizontal turn. 3 Figure 7- Wyodak Coal Tunneling Another industry that would not be able to use belt conveyors without the ability to negotiate horizontal curves is construction tunneling. Tunnels are being bore around the world for infrastructure such as waste water and transportation. The most efficient method of removing tunnel muck is by connecting an advancing conveyor to the tail of the tunnel boring machine. But these tunnels are seldom if ever straight. One example in Spain is the development of a 10.9m diameter tunnel under Barcelona as part of the Metro (Train) Extension Project. Continental Conveyor Ltd. installed the first 4.7km conveyor as shown in Figures 8 and 9 and has recently received the contract to install the second 8.39 km conveyor. Figure 8- Barcelona Tunnel Plan View Figure 9- Inside Tunnel In another example, Frontier Kemper Construction is currently starting to bore 6.18 km (20,275 ft) of 3.6m (12 foot) diameter tunnel for the Metropolitan St. Louis (Missouri) Sewer District. The Baumgartner tunnel (Figure 10) will be equipped with a 6.1 km conveyor of 600mm wide belting with 4 intermediate drives. Figure 10- Baumgartner Tunnel Plan View Pipe Conveyors And if conventional conveyors cannot negotiate the required radii, other variations of belt conveyor such as the Pipe Conveyor might be used. Figure 11- Pipe Conveyor In its simplest description, a pipe conveyor consists of a rubber conveyor belt rolled into a pipe shape with idler rolls. This fundamental design causes the transported material to be totaled enclosed by the belt which directly creates all the advantages. The idlers constrain the belt on all sides allowing much tighter curves to be negotiated in any direction. The curves can be horizontal, vertical or combinations of both. A conventional conveyor has only gravity and friction between the belt and idlers to keep it within the conveyance path. Figure 12 Another benefit of pipe conveyor is dust and/or spillage can be reduced because the material is completely enclosed. A classic example where both environment and adaptability to path were particularly applicable was at the Skyline Mine in UT, USA (Figure 12). This 3.38 km (11,088 ft) Pipe Conveyor was installed by ThyssenKrupp Robins through a national forest and traversed 22 horizontal and 45 vertical curves.4 Metso Rope Conveyor Another variation from conventional is the Metso Rope Conveyor (MRC) more commonly known as Cable Belt. This product is known for long distance conveying and it claims the longest single flight conveyor in the world at Worsley Alumina in Australia at 30.4 km. With Cable Belt, the driving tensions (ropes) and the carrying medium (belt) are separated (Figure 13). Figure 13- MRC- Straight Section This separation of the tension carrying member allows positive tracking of the ropes (Figure 14) which allow very small radius horizontal curves to be adopted that defeat the traditional design parameters based on tension and topography. Figure 14 MRC vs. Conventional Conveyor in Horizontal Curve Figure 15- MRC at Line Creek, Canada Figure 15 shows a 10.4 km Cable Belt with a 430m horizontal radius at Line Creek in Canada. Vertical Adaptability Sometimes material needs to be raised or lowered and the conventional conveyor is limited to incline angles around 16-18 degrees. But again non-traditional variations of belt conveyors have been quite successful at increased angles as well as straight up. High Angle Conveyor (HAC.) The first example manufactured by Continental Conveyor & Equipment Co. uses conventional conveyor components in a non-conventional way (Figure 16). The concept is known as a sandwich conveyor as the material is carried between two belts. Figure 16 Continental’s 100th installation of the HAC was a unique shiftable installation at Mexican de Canenea’s heap leach pad (Figure 17). Figure 17 Pocketlift. The second example shows a non-traditional belt construction which can be used to convey vertically (Figure 18). This Metso Pocketlift. belt was installed by Frontier Kemper Constructors at the Pattiki 2 Mine of White County Coal in 2001 (Figure 19). It currently lifts 1,818 mtph of run-of-mine coal up 273 m (895 ft). 5 Figure 18 Figure 19- Pattiki 2 Mine Distributed Power One of the most interesting developments in technology in the recent past has been the distribution of power along the conveyor path. Is has not been uncommon to see drives positioned at the head and tail ends of long conveyors and let the tail drive do the work of pulling the belt back along the return run of the conveyor. But now that idea has expanded to allow designers to position drive power wherever it is most needed. The idea of distributing power in multiple locations on a belt conveyor has been around for a long time. The first application in the USA was installed at Kaiser Coal in 1974. It was shortly thereafter that underground coal mining began consolidating and longwall mines began to realize tremendous growth in output. Mining equipment efficiencies and capabilities were improving dramatically. Miners were looking for ways to increase the size of mining blocks in order to decrease the percentage of idle time needed to move the large mining equipment from block to block. Face widths and panel lengths were increasing. When panel lengths were increased, conveyance concerns began to appear. The power and belt strengths needed for these lengths approaching 4 -5 km were much larger than had ever been used underground before. Problems included the large size of high power drives not to mention being able to handle and move them around. And, although belting technology could handle the increased strength requirements, it meant moving to steel reinforced belting that was much heavier and harder to