裝配圖基于YQP36預加水盤式成球機設計
裝配圖基于YQP36預加水盤式成球機設計,裝配,基于,yqp36,加水,盤式成球機,設計
文 獻 資 料
專 業(yè) 機械設計制造及其自動化
學 生 姓 名 楊 聞 達
班 級 B材機022
學 號 0210120211
指 導 教 師 楊 曉 紅
文 獻 資 料
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畢業(yè)實習報告
專 業(yè) 機械設計制造及其自動化
學 生 姓 名 楊 聞 達
班 級 B材機022
學 號 0210120211
指 導 教 師 楊 曉 紅
日 期 2006.03.19
實 習 報 告
一、 概述
實習的主要目的在于通過此次實習對具體建材機械設備的設計方法、設計規(guī)范、加工工藝、制造過程和裝配過程有所掌握及對各種加工設備的使用有所了解，對所學專業(yè)知識的鞏固，并對畢業(yè)設計和畢業(yè)論文的撰寫針對性地和最大限度地準備素材，收集實際生產(chǎn)管理資料，同時增強自身的分析和解決工程問題的能力、實踐能力、自學能力及創(chuàng)新能力。間接地了解機械生產(chǎn)企業(yè)運作管理，為以后的工作及創(chuàng)業(yè)增加砝碼，打下堅實的基礎(chǔ)。
實習的具體目的在于通過此次實習熟悉機立窯、回轉(zhuǎn)窯、球磨機、破碎機、選粉機、輸送攪拌機械等的生產(chǎn)過程及控制方式，特別是了解預加水成球盤（YQP36）的設計、制造、安裝和調(diào)試，了解成球盤結(jié)構(gòu)功能、成球過程、最新的成球技術(shù)及成球盤在整個水泥生產(chǎn)過程的具體作用。
畢業(yè)實習是一次針對畢業(yè)設計的綜合性的實踐，是一次很好的專業(yè)知識的運用訓練，是一次從學校向社會過渡的準備。
二、 實習過程
本次所到的實習基地有江蘇鵬飛集團建材設備廠、江蘇鵬飛集團總部、江蘇海建集團、江蘇蘇亞公司和鹽城聯(lián)鑫水泥有限公司。具體實習過程如下：
3月7日在江蘇鵬飛集團建材設備廠進行建材裝備實習，主要熟悉回轉(zhuǎn)窯、球磨機、烘干機、破碎機、輸送攪拌機和預加水成球盤等及其輔助零部件的結(jié)構(gòu)、設計、制造工藝、安裝的具體過程。
3月8日在江蘇鵬飛集團總部進行建材裝備實習，主要熟悉管磨機、回轉(zhuǎn)窯等大型設備的結(jié)構(gòu)工藝。
3月9號—3月10日在江蘇海建集團進行裝備實習，主要熟悉回轉(zhuǎn)窯、球磨機、烘干機、輥壓機、打散機、成球盤、輸送攪拌機和選粉機等及其輔助零部件的結(jié)構(gòu)、設計制造安裝的具體過程。
3月14日在江蘇蘇亞公司進行裝備實習，主要了解各種選粉機和除塵器的構(gòu)造和制造安裝過程。
3月16日在鹽城聯(lián)鑫水泥有限公司實習，主要了解采用立窯生產(chǎn)水泥的各種設備的結(jié)構(gòu)和技術(shù)要求、生產(chǎn)流程和功用的實現(xiàn)。
三、 實習內(nèi)容
對于回轉(zhuǎn)窯的認識：
1.回轉(zhuǎn)窯結(jié)構(gòu)組成
濕法回轉(zhuǎn)窯簡圖
1-煤倉；2-燃燒器；3-窯頭罩；4-簡體，5-輪帶和支承托輪；6-傳動裝置；7-窯內(nèi)熱交換器；8-料漿喂料器，9-煙室；10-電收塵器；11-煙囪；12-排風機；13-熱料冷卻
筒體、輪帶、托輪、支承裝置、傳動裝置、窯頭和窯尾密封裝置等部分組成
2 .回轉(zhuǎn)窯機械結(jié)構(gòu)特點
薄壁筒體。形大體重。多支點的支承，熱工設備。
3 .在回轉(zhuǎn)窯設計、制造、運輸、安裝等各環(huán)節(jié)中，應始終考慮該機器“大而重”的特點，并切實保證“直而圓”的要求。
對立窯的認識：
機械立窯主要由喂料裝置、窯罩煙囪、窯體、卸料裝置、傳動裝置，電氣控制、料封和料位控制、收塵裝置組成。
卸料裝置有塔篦和立窯底座構(gòu)成。塔篦主要由鑄造而成，起到卸料和破碎的作用，所以塔篦本身就需要有很好的結(jié)構(gòu)來避免摩損。立窯底座中心與主軸中心一致，在側(cè)邊還布有下料管和風管。風管給煅燒的料球通風一達到合理分布立窯內(nèi)預熱帶、燒成帶和冷卻帶的分布及料球的燃燒質(zhì)量。
對球磨機的認識：
1 .球磨機的分類
操作方法不同而有開流閉流之分；卸料方式不同而有中卸和尾卸之分；傳動方式不同而有邊緣傳動和中心傳動之分。
邊緣傳動常用中空軸軸承支承，而中心傳動常采用滑履支承，其主要用于大型磨機上。
2 .球磨機的結(jié)構(gòu)基本上由以下五部分組成：
2.1 進料裝置 包括下料斗螺旋筒及襯板等部件
2.2 支承裝置 分兩端主軸承式，兩組輪帶托輪式．一端滑履軸承、一端主軸承，兩端都是滑履軸承。采用鑄鋼底座，從而起到吸振作用
球磨機主軸承承擔整個磨機回轉(zhuǎn)部分的重力，一般由軸瓦、軸承蓋、軸承座、潤滑及冷卻系統(tǒng)所組成。3米以上磨機要求其軸承進行潤滑再潤滑。
2.3 回轉(zhuǎn)部分：包括中空軸、端蓋、筒體、隔倉板、襯板。
2．3．1 筒體：
筒體是球磨機的主要工作部件之一，物料在筒體內(nèi)被研磨體沖擊和研磨而磨成細粉。筒體是用鋼板卷制焊接而成的圓筒形薄壁殼體，在筒體上還開有磨門。
制造筒體的材料有普通結(jié)構(gòu)鋼A3，鍋爐鋼板20 g，20號優(yōu)質(zhì)結(jié)構(gòu)鋼和16Mn低合金結(jié)構(gòu)鋼。這些材料的強度、塑性和可焊性都能滿足要求。常采用三輥式和四輥式的卷板機卷曲而成。
筒體上固定襯板和隔倉板的螺栓孔，應根據(jù)襯板尺寸等距開設，縱橫成行。筒體焊縫中心與螺栓孔中心應不少于二倍半的螺栓直徑，因焊縫附近有較大的應力集中影響，同時也便于螺栓的固定。
筒體在制造中要滿足下列要求：筒體斷面要圓，筒體縱向中心線要直，法蘭端面與縱向中心線垂直。筒體各部分存在著內(nèi)應力，是磨機工作時出現(xiàn)裂縫的根源，所以在筒體焊接，焊縫要叉開，外圓點焊，內(nèi)圓線焊，切割磨門和鉆孔后，應當退火，就有可能防止裂縫出。直徑3米以上的筒體一定要求退火處理。常用波口有X形和V形。
筒體兩端的法蘭止口圓與磨頭要同心，端蓋與筒體結(jié)合面要精加工，兩端法蘭止口要彼此平行，并與筒體縱向中心線垂直， 磨頭和法蘭螺栓孔要精確重合，并有不少于15%的鉸孔螺栓栓起定位作用， 螺栓要用同種牌號的鋼制造,并要均勻地擰緊。
對于筒體的加工采用落地車床，如C6031（最大直徑：3150mm，最大長度：2000mm）。其采用錐體盤夾緊，通過摩擦帶動通體周向轉(zhuǎn)動。
筒體為了維持其成形后的圓度，常采用工裝，同時其也用于調(diào)圓作用，如米字撐。
2．3．2 磨頭：
磨頭由中空軸和端蓋等部分組成，是磨機的主要零件之一，承受著整個磨機的動載荷，磨頭的結(jié)構(gòu)形式主要有兩部，一種是中空軸和端蓋鑄造成一整體；另一種磨頭是把端蓋和中空軸分別鑄造，加工后再組裝到一起。
一般大中型磨機采用鑄ZG35 作為中空軸的材料，小磨機因為受力較小，考慮到成本低和取材容易，一般用鑄鐵或球墨鑄鐵作為磨頭材料。
進料螺旋筒磨機端需要配鋼球擋圈，以免砸傷螺旋，同時也起到均勻穩(wěn)定出料的作用。另一種方法是采用改變螺旋螺距的大小來達到進料快速，出料均勻穩(wěn)定的效果。
出料段螺旋的螺距一致，主要要求其出料均勻穩(wěn)定。
中空軸卸料段外圓處裝有回轉(zhuǎn)篩，回轉(zhuǎn)篩除有起到篩料選料的作用外，還有排出破碎鋼球的作用，在其結(jié)構(gòu)上都有體現(xiàn)。最后安裝入出料斗，對于出料斗要求有很好的密封。
2．3．3 襯板：
襯板的表面形狀：平襯板，壓條襯板，突棱襯板，階梯襯板，平襯板，壓條襯板。
襯板類型
a） 壓殺襯板；b）突棱襯板；（c）波形襯板；d）階梯襯板；e）平襯板；
f）波紋襯板；（g）半球形襯板 l一壓條；2一平襯板
2．3．4 隔倉板：
隔倉板上裝有篦板，其對磨料進行篩選、分倉，從而對不同粒徑的磨料進行相對的粉磨。同時也隔開不同直徑的磨球。這樣不會導致過粉磨，增加電耗。
2．4 卸料裝置：
由螺旋出料筒、出料中空軸、回轉(zhuǎn)篩和出料斗組成。對于邊緣傳動的磨機而言，其出料中空軸與中心傳動的磨機的有所不同，相應的出料斗也不同，主要就是存在中空軸端還有連有聯(lián)軸器的結(jié)構(gòu)。
2．5 傳動裝置：
中心和邊緣傳動兩種形式，包括電機減速機、聯(lián)軸器及邊緣傳動的大小輪。
對于邊緣傳動形式的磨機而言，小齒輪軸通常有中心孔和起吊孔，從而在起吊的過程中不因其重量而帶來起吊的不便，避免影響其加工后的質(zhì)量和出現(xiàn)人身安全。
對除塵器的認識：
XLK型旋風收塵；CLT／A型旋風收塵器；XLP型旋風收塵器；組合式旋風收塵器；氣環(huán)反吹袋式收塵器；脈沖袋式收塵器；機械回轉(zhuǎn)反吹袋式收塵器；反吹風袋式收塵器；旋風順氣脈沖袋式收塵器。
對于旋風收塵器有采用二次出風。在其下端側(cè)邊有二次出風管，同時它也簡化了旋風的出風路徑。它改變了以往的旋風收塵器的功耗大的問題，將兩次出風再次回到選粉機，大大降低了功耗。
對輥壓機的認識：
輥壓機主要結(jié)構(gòu)：輥壓機主要結(jié)構(gòu)包括壓輥軸、傳動、機架、液壓、喂料。
所能達到效果有：55MPa的壓力，兩輥輪相對轉(zhuǎn)動，將30%～45%的料壓成塊狀。
輥輪在堆焊前外圓面上有加工的條紋，這樣保證堆焊的粘結(jié)質(zhì)量。輥輪的外圓邊處還有沉圓，以保證堆焊后的焊料能軸向固定。
對于輥壓機的主軸加工中為了對軸起到冷卻的效果，常有在軸上鉆中心通孔。主軸常采用鍛鋼加工制造而成。
對螺旋輸送機械的認識：
螺旋是螺旋輸送機的基本構(gòu)件，它是由軸和螺旋面組成的。另外還有電機和減速機等組成。軸承常采用調(diào)心軸承從而承受拌料時的軸向力。螺旋輸送機內(nèi)的螺旋面大多才用螺旋葉片按90°分布在軸上，也有采用螺旋葉片和螺旋面相結(jié)合的。對于一臺螺旋輸送機，常有在前段采用螺旋面式，后段采用螺旋葉片式，從而保證進料均勻，以便能在加水攪拌下能形成高質(zhì)量的球核。
對斗式提升機的認識：
斗式提升機的主要部件有：料斗、牽引構(gòu)件、機首、底座和中間罩殼等。常用的料斗有三種結(jié)構(gòu)形式：淺料斗、深料斗和導向邊料斗。斗式提升機所用的牽引構(gòu)件有輸送膠帶和鏈條。提升機所用鏈條有關(guān)節(jié)鏈及焊接鏈。提升機的中間罩殼，在固定式的裝置中，應用由 2～4 mm的薄鋼板焊成。
對烘干機的認識：
烘干機出料端一般用密封鋼皮密封，其內(nèi)部的揚料板采用不同的角度和長度以及之間的間距來調(diào)整揚料烘干的效果，從而達到節(jié)能高效的目的。
對成球盤的認識：
成球盤的成球過程中，除了有大盤由主電機通過減速機，大小齒輪的傳動所得到的轉(zhuǎn)動外，還有動力刮刀的轉(zhuǎn)動，另外也有無動力刮刀的自身轉(zhuǎn)動。
盤體有兩種：可調(diào)容量式和固定容量式盤體?？烧{(diào)式的盤體主要通過螺母螺栓的軸向調(diào)節(jié)實現(xiàn)。
有見到的傳動例子：
1． 電機（380V，8.5KW）+齒輪外嚙合減速器（i=15.75）
2． 三相電機（380V，16KW，1440r/min）+行星輪減速器（i=25）
3． 小齒輪要求進行調(diào)質(zhì)HB241-286處理，m=10,z=28,α=20°，A=625，ha*=1，ξ=0，h=225,Fp=0.18,fd=±0.045。
鉸孔套采用35材料，先鍛打成毛坯而后車削。
盤體的傾斜度要求在40°～55°
鉆腳座孔：1.先打小孔以便定位；2.鉆大孔。
四、 球磨機大齒輪加工的分析
大齒輪有以下2種加工工藝：
1.1 準備half結(jié)構(gòu)鑄造毛坯à銑half結(jié)構(gòu)的結(jié)合端面à畫線鉆孔à連接兩half結(jié)構(gòu)的輪圈à鉸孔à鉸制螺栓螺母連接à以輪緣內(nèi)圓為粗基準、車外端面、輪轂內(nèi)圓端面、輪緣外圓à以輪轂內(nèi)圓，輪緣側(cè)面為精基準車另一測輪轂側(cè)面、輪緣側(cè)面à刨齒à滾齒。
1.2 準備half結(jié)構(gòu)鑄件毛坯à銑half結(jié)構(gòu)的結(jié)合端面à合并half結(jié)構(gòu)，焊接à以輪緣內(nèi)圓為粗基準、車外端面、輪轂內(nèi)圓端面、輪緣外圓à以輪轂內(nèi)圓，輪緣側(cè)面為精基準車另一測輪轂側(cè)面、輪緣側(cè)面à拆焊à 鉆孔à對孔焊接à鉸孔à刨齒à滾齒。（其中刨齒為了提高效率，降低成本，質(zhì)量相對于直接滾齒稍差。）
有時在兩half結(jié)構(gòu)為了讓對孔合并方便常采用定位銷的方法定位兩half結(jié)構(gòu)。
五、 實習感想
通過此次實習，對水泥生產(chǎn)工藝和設備有進一步的認識，特別是水泥生產(chǎn)的過程裝備方面有更詳細的了解及對各設備內(nèi)部的結(jié)構(gòu)和作用有更深層次的認識。此次實習讓我們看到了書本上沒有的東西，也深知具體的技術(shù)問題的分析解決的能力是書本學習所無法給的，對于我們工程人員特別要加強自身的工程意識。此次實習也讓我們重新學習了制圖測繪、機械原理、機械設計、機械制造、水泥工藝和水泥設備等基礎(chǔ)專業(yè)知識，為我們的畢業(yè)設計和以后的工作打下基礎(chǔ)。
在實習過程中，主要對成球盤和球磨機有進一步的認識。
對于成球盤，了解了它的過去和現(xiàn)在最新的技術(shù)，現(xiàn)在的發(fā)展方向是向節(jié)能高效上發(fā)展。對于不同的公司，其產(chǎn)品有很大的不同，主要有在傳動方式和傳動布局有所不同。在盤體設計制造安裝上也有不同，主要四采用是否可調(diào)容量和采用材料的不同，有采用剪裁不同的鋼板進行焊接，也有大量使用型材，特別是槽鋼和工字鋼的使用，從而在強度和成本上有更大的突破。在刮板方面，最近為了節(jié)省能源消耗，使用無動力刮板或有動力刮板和無動力刮板結(jié)合使用，但對于無動力刮板的設計上仍存在缺陷，在常使用V形刮板已在成球質(zhì)量上就如此，現(xiàn)在更多的是采用攪拌式的邊刮刀和底刮刀，這樣的改進也解決了成球質(zhì)量上的要求。調(diào)角器的設計上除了能調(diào)整盤體傾斜的角度外，還要求能鎖緊的效果，其中采用蝸輪蝸桿傳動和螺母螺栓軸向傳動能有更好的效果。這樣的改進從而能保證質(zhì)量。
對于球磨機，有中卸式和尾卸式，同時也有中心傳動式和邊緣傳動式。此次實習就其具體的結(jié)構(gòu)有了全面的認識 ，從支承裝置、傳動裝置、筒體結(jié)構(gòu)、進料裝置和出料裝置等都有深入的理解。
此次實習鍛煉了我的分析和解決工程問題的能力、獨立思考和自學的能力和實踐能力。此次實習所收集的資料為我畢業(yè)設計做好了充分的準備。
8
Feasibility study requirements for a new cement plant
R.Hogg, D Frame and M.E. Asim, WS Atkins Consultants, UK, discuss the theory and practice of undertaking large cement plant projects.
FOR SPANISH AND FRENCH VERSIONS PLEASE REFER TO THE SPECIAL TRANSLATED SECTION AT THE BACK OF THE ISSUE
Introduction
The decision to start the construction of an entirely new cement plant facility, or a major capacity extension at an existing cement works, should always be based on a detailed techno-economic feasibility study. Such a study will indicate to the promoter the viability of the business in terms of the best technical solution, the overall capital and operating casts, the magnitude of the operation in terms of production and workforce needed, and the return on his investment over a period of time.
A typical feasibility study deals with the following issues:
Marketing study.
Raw materials proving.
Site studies.
Conceptual engineering and process design.
Analysis of alternatives.
Project cost including infrastructure.
Project schedule.
Investment analysis, risk assessment, development of financial structures.
Project finance.
Discussion with financing institutions.
Whilst any feasibility study must include technical aspects, it is important to realize the full implications of marketing research and accurate financial projections.
Pro-feasibility study
In order to minimize front end expenditure and to quickly obtain a firm indication of the likely project viability, a pre-feasibility study is performed.
The pre-feasibility study is carried out at low cost, but in sufficient detail to show whether a full feasibility study is justified. The pre-feasibility study will examine the market place, the raw materials, capital and operating costs, and develop a business plan to show the likely returns on the investment, and identify the risks and scale of operation involved.
Typically this exercise will take four to six weeks to complete, commencing with a site visit. However, the study is largely performed by desk research and reference to the in-house date base. The site visit is used to determine the suitability of raw materials for cement manufacture, local building and civil engineering costs, cost of land and peculiarities of the particular site location, and local cost of consumables required in the operation of the plant. The desk research concentrates upon current plant and machinery costs, financial and marketing considerations and preliminary plant sizing and determination of the process route.
In the event of the pre-feasibility study showing a clear indication that it is worthwhile to proceed with the project, then a full feasibility study can be initiated.
Full feasibility study
Market research
The objective of the market study is to establish the demand for the various types of cement in the context of the region or market area of the proposed plant. The study seeks to establish the current and forecast cement usage over a 5-7 year period. The forecast is then used together with the indicated selling prices to generate the likely revenue stream for the proposed operation.
The consultant must have considerable experience in the global cement industry and be able to approach a feasibility study with an excellent knowledge of prevailing market conditions and likely trends. Each individual company and market does, however, present a unique set of circumstances which must be fully understood. The normal approach adopted is first to study the company and identify its strengths and weaknesses, strategic direction and motivation. This is essential in providing an immediate picture of the company’s likely success in achieving its aims.
The second stage of the marketing survey, desk research, puts the initial discussions into context by examining a wide range of published data relevant to the industry.
Sources of published data are collated and compared by a team of researchers and consultants in an operation to substantiate known trends and uncover new information. It is not sufficient to rely on information several months old, and without an international perspective, trends in cement production and demand are frequently misleading.
Collecting published data is an on-going process, but having established a background to the study, information should, where possible, be verified using independent sources with firsthand accounts of the industry and its outlook. Companies, government organisations and other industry associations are often willing to provide their own assessment lf markets, but care needs to be taken not to compromise any party prepared to give its view.
Armed with a comprehensive selection of published data and industry opinion, the job of the consultant at this stage is to accurately define not only the market size for a particular product, but the likely change in that market. Such changes are often predicted by historic relationships between, for instance GDP and overall construction activity; economic growth and housing starts of cement consumption and population size. Figure 1 illustrates this point. Without taking into account subjective opinion and recognizing changing user requirements for different cement types, such forecasts can be flawed. Analysis of such factors is particularly important in lesser developed countries where impressive growth rates can change the balance of construction activity over remarkably short periods of time.
Other economic information likely to have a bearing on the market are government tariffs, import duties and sector subsidies. Even in free market areas, many aspects of economies are regarded as being of strategic importance and governments frequently strive to preserve national interests wherever possible by fixing prices of imposing import tariffs. Should import tariffs be relaxed of prices allowed to move in line with supply and demand, there will be an appreciable change in the market conditions. National companies, for instance, might suddenly find themselves uncompetitive. With cheaper imports, the balance between cement grinding and clinker production requirements could change quite dramatically. It would be up t the government to accommodate these changes, but one of the principle tasks of the consultant is to anticipate them.
This last point highlights what is perhaps the single most important yet difficult to determine aspect of a market study: competitor reaction. Knowing of others investment plans, government licensing, likely dates of completion, principle contractors involved and distribution partners is difficult and time consuming, but it is not enough. Competitors are not just nationals of those who have historically sold their product through the same predictable channels of distribution. There are an increasing number of companies who would like to reduce dependence on suppliers by vertically integrating their operations. This could entail building their own plant or developing their own deep water terminal to import cement directly. Others might decide to diversify into selling, for example, ready missed concrete. Some large users might be on verge of entering into long term agreements with one company or looking to buy form further afield. The combinations are numerous but it is up to the company investing in expensive plant and machinery to understand its customers and convince both itself and the investors that it really does have the best view of the market.
Raw materials proving
The volume and quality of the raw material deposits have to be established with accuracy. A wide ranging search for raw materials may start with desk research and consultation with National Geological Survey data and available geological mapping. The search will include examination of aerial photography records and satellite imagery e.g. Landsat or SPOT.
The desk research is followed buy site visits to the proposed location by geologists who take the study a step forward by making on-site examinations of previously identified geological horizons and outcrops. The first samples are taken by channeling from promising outcrops, road cuttings, recent excavations or from purpose excavated test pits. Field testing of the samples is required to provide an initial indication of the calcium carbonate, silica, alumina and iron content of the deposit. The testing is simple, rapid and economical and the geologist can adjust the field investigations and maximize the recovery of useful information.
The most promising samples are chemically analysed in testing laboratories and when sufficient data has been obtained in terms of chemical quality, and the probable volume established, a decision to mount a full drilling campaign can be made.
The primary raw material or limestone, is core drilled and careful records of the geological progression is made as the cores are recovered, recorded and laid sequentially in the core boxes,(Figure 2). Individual and composite samples are taken from the cores and sent to laboratories experienced in the testing of cement raw materials. In order to minimize drilling costs is essential that the initial results of the first borehole are analysed rapidly and the results known in order to make further decisions on location, angle and direction of subsequent boreholes.
The information obtained from the chemical analyses and the geological record derived from the cores in then used to establish the geological structure and the volume of the deposit. The optimum quarry developments are then developed.
The secondary raw materials, clays or shales, may be proven by means of auger drilling of by test pit excavation using mobile hydraulic excavators or in some cases by hand excavation. These materials are similarly recorded and chemically analysed as for the limestones.
Using the chemical analysis of the raw material, computerized raw mix designs can be carried out. The in-house program used has several facilities which can be called upon. Firstly, all the necessary standard equations which must be satisfied for lime saturation, silica ratio, alumina ratio, hydraulic modulus, etc., are built into the program. Secondly, the mix design can be refined by adjusting the compound composition and observing the effect upon the standard ratios. Finally, cost factors can be added to the raw materials to obtain the optimum raw mix which minimizes the most expensive raw materials, but satisfies the above criteria.
Process design
The optimum process route for a specific plant is dependent upon a number of factors including the physical and chemical nature of the raw material deposits. The selection of plant and machinery is made based on the following factors”
Disposition of the raw material deposits.
Moisture content and other physical properties of the raw materials.
Level of undesirable chemical elements.
Mineralogy (particularly the content and size of silica).
Abrasiveness, grindability and the burnability of the raw materials.
Fuel types and relative costs.
Environmental protection requirements.
Electrical power availability, cost and energy efficiency requirements.
Site topography and congstraints.
Market constraints.
Labour and maintenance constraints.
The disposition of the raw materials in terms of dip and strike and physical location dictate how the primary and secondary raw material quarries are opened up, how they are to be worked and how the access roads are to be developed. The geological method of deposition and hardness of the raw materials will also determine how the quarry is to be planned and the methods of extraction determined.
The moisture content of the raw materials and the change in their characteristics as the moisture content alters has an important effect upon the choice of the primary crusher and storage systems. The moisture content has even greater implications when considering the raw milling system to be proposed in conjunction with the optimum temperature of preheater exit gas. A balance has to be struck between the requirements of the kiln system, the number of cyclone stages that can be used, and the heat requirements of the raw mill for raw materials drying.
The level of undesirable chemical elements in the raw materials, such as potassium, sodium, magnesia, chlorides and sulfur requires careful consideration in the selection of the type of kiln system. The varying levels of impurity elements in conjunction with the sulfur in the raw material and possible additional sulfur intake from the kiln fuel, lead to the necessary decisions to be made relating to the acceptance and sizing of a bypass system.
The mineralogy can vary greatly among raw materials in different countries. The method of deposition and the occurrence of the chemical elements in each of the raw materials can have a marked effect on the characteristics of combination in the kiln burning process. Notably this leads to variations in kiln fuel conditions. Predictions upon how the raw-materials will behave when combined in the necessary proportions to obtain a commercial cement, are based upon laboratory burning and grinding tests conducted as part of the feasibility study.
Energy and fuel usage are two key matters high on the agenda of all potential and existing cement plant operators. The cement industry has always been very conscious of making the maximum use of heat energy, and to this end heat transfer from the kiln gases to the raw materials, of from the hot clinker to the combustion air, has always been utilized.
Today more than ever the efficient use of energy and fuel is sought affair and a range of plant and equipments available for consideration. Technical economy of scale is also an important factor and where the market justify large capacity plant, correspond with reductions in the cost of products are achieved.
Energy consumption is be reduced through the use of roll-milling systems for raw meal in plant of tube mills, high efficiency separators in both the raw milling and cement milling departments, low pressure drop cyclones in the preheater of the burning process, and by the preheater of high pressure grinding rolls, and recent introduction of the horizontal roller mill, the so-called Horomill. The selection of the optimum planning processes ensures that the KWh/h electrical power consumption minimised.
Fuel consumption is reduced the introduction of efficient cyclones construction with heat resistant tubes and an increase in the number of stages of preheater to mount maximum use of the hot gases leaving from the kiln. Fuel consumption is also siderable affected by the designation ancillary plant such as the kiln separators, gas ducting, kiln burner, flow control valves and instrumentation.
Another recent development is the transfer of all the hot exhausted gases form the clinker cooler back onto the raw mill, thus saving on the heat required for drying the raw material. This arrangement also has the acute advantage of reducing the capital of the plant by the elimination of a cipitator or other clinker cooler collection system and its associating equipment.
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