【正文】 用在相反的或上游的盤片上的線性壓力迫使盤片離開閥座。如果尺寸相同，并且在相同壓力下操作，平行閥與螺旋閥相比，所要求的軸向力較小，而軸向力是由正閉合包圍，只要稍加考慮就可以知道原因。因此密封可以分為兩大類，靜態(tài)的和動態(tài)的。而且對于主要的定做密封的設(shè)備要進(jìn)行特殊考慮。被分為兩種類型，界面密封和間隙密封。間隙密封描繪了包括四個(gè)截然不同的種類的家族。間隙密封能在機(jī)器內(nèi)部與環(huán)境之間產(chǎn)生一個(gè)壓力差。間隙密封的實(shí)例是黏膠密封，速度密封和軸封?，F(xiàn)在使用的更加廣泛而且證明了對一種工業(yè)的重要性。機(jī)械密封目前的技術(shù)水平已發(fā)展到這樣的程度，從105托的高真空度到5000磅/平方英寸都能處理。重要密封環(huán)的一個(gè)是連在軸承上并且隨它一起運(yùn)動，另一個(gè)密封環(huán)是固定的并與殼體相連。任何流體泄露時(shí)都流過這個(gè)表面因?yàn)樽饔迷谳S線方向的里使得摩擦接觸一直存在。穩(wěn)定的接觸防止了或最小化了摩擦區(qū)域的泄露。其次，潤滑劑用一個(gè)微小的薄膜將介質(zhì)覆蓋從而減小摩擦同時(shí)建立以份額緊密的密封。對一個(gè)機(jī)械斷面來說做一個(gè)軸的可靠性分析是不可能的，因?yàn)?，每一個(gè)機(jī)械密封都是在一個(gè)純經(jīng)驗(yàn)注意基礎(chǔ)上設(shè)計(jì)發(fā)展的，任何新的密封都設(shè)計(jì)都必須以經(jīng)驗(yàn)為主的測試，因?yàn)閷γ芊馓匦允亲詈蟊憩F(xiàn)預(yù)測并沒有可靠性理論基礎(chǔ)。自動化化學(xué)過程原因某些或所有可能的下列基本利益的實(shí)現(xiàn)當(dāng)自動控制時(shí)引入化學(xué)過程：（1）一種化工過程，不管是在實(shí)驗(yàn)規(guī)模的設(shè)備內(nèi)或在中間實(shí)驗(yàn)裝置內(nèi)，還是在生產(chǎn)規(guī)模裝置內(nèi)進(jìn)行，都能夠在無操作人員活化工技術(shù)員看管的情況下連續(xù)運(yùn)行。此外，自動化控制，無需人員在鄰近的危險(xiǎn)設(shè)備。這可能是由放置一個(gè)水銀溫度計(jì)中填充的解決方案，觀測的溫度，然后手動調(diào)整電壓的爐具通過變阻器加熱元件，使溫度保持在理想的范圍。基本上，這一功能的控制系統(tǒng)，來衡量變量的值，溫度，然后產(chǎn)生一個(gè)反應(yīng)限制其偏離參考點(diǎn)，在50 ℃下?？梢钥闯?，這個(gè)系統(tǒng)包含相同的四個(gè)基本要素的手動控制系統(tǒng)前段所述。流動這種情況是可以預(yù)想，重要的是物料平衡要求的過程中，他任何時(shí)候都保持人。另外，適當(dāng)?shù)臏囟瓤刂瞥３Ｊ鞘直匾某晒\(yùn)作了許多分離過程，如蒸餾，結(jié)晶。液位水平控制往往與流量控制。成分控制根據(jù)物料的性質(zhì)，采用一系列不同的技術(shù)，就可實(shí)現(xiàn)物質(zhì)組成的控制③?；旌衔锏拇_切成分往往擁有一套獨(dú)特的物理特性?；瘜W(xué)特性，往往是監(jiān)測控制的目的包括pH值，氧化還原電位和電導(dǎo)率。v230。In the case of biomass bustion , however, this will be possible on only very large scales, whereas atmospheric biomass gasification is projected to attain these efficiencies on considerably smaller scales。kei??n] 可是對于生物質(zhì)能，它將可能僅在非常大的范圍內(nèi)獲得，然而在大氣中的生物質(zhì)氣化將在相當(dāng)小的范圍內(nèi)獲得這些效能。It is further parable to a coalfueled power plant with respect to flue gas emissions and solid residues from the bustion process and flue gas —；bustion—；flue—煙道；這是進(jìn)一步就煙氣排放和在燃燒過程、煙氣清理中的固體殘留與燃煤發(fā)電廠的比較。C and 595176。Increase the toughness。Secure the proper grain structure。it may even crack if make the steel more ductile, it must be is identical with annealing, except that the steel is air cooled。在退火中，使鋼加熱到轉(zhuǎn)變溫度以上的一個(gè)適宜溫度后緩慢地冷卻。淬火淬火就是通過冷浸鋼，那就是使鋼從轉(zhuǎn)變溫度以上的一個(gè)溫度快速冷卻。至于該過程怎樣使鋼變得有韌性，我們將在以后討論。改善熱處理鋼可能產(chǎn)生的粗糙晶粒的晶粒結(jié)構(gòu)。提高切削性能提高導(dǎo)電性。但是，在鋼的應(yīng)用部分里，強(qiáng)度不是唯一的必需考慮的性能?；鼗鹗怯脕硎柜R氏體獲得可延展性，通常強(qiáng)度會降低一些。回火過程是這樣達(dá)到的：把淬火后的部分加熱到轉(zhuǎn)變溫度的某點(diǎn)，然后維持這溫度一個(gè)小時(shí)或更多，這要根據(jù)部件的大小判斷。退火淬火和回火兩個(gè)熱處理過程來生產(chǎn)高強(qiáng)度的鋼以便抵抗沖擊和變形而不受破壞。退火過程退火過程就是加熱鋼到稍低于最低轉(zhuǎn)變溫度的一個(gè)溫度后保持一會兒。在完全退火中，冷卻必須要非常緩慢地進(jìn)行從而形成粗糙的珠光體。正火正火過程包括將溫度加熱到第三轉(zhuǎn)變溫度以上，然后讓該加熱部分在空氣中冷卻直到與空氣溫度相同。任何一塊鋼，它的組成部分通常是不統(tǒng)一的。這樣鋼的成分就會更均勻從而使熱處理方法更統(tǒng)一。那就是說，金屬的收縮可以被觀測到。打算使金屬收縮的力并沒有減少，當(dāng)金屬再次被冷卻時(shí)，這個(gè)力與內(nèi)應(yīng)力一樣不變。C，假設(shè)所有的部分被均勻加熱，然后緩慢冷卻到室溫。因此，對薄殼體有：W=PrEt說明：W=半徑的偏差值，E=彈性橫量當(dāng)rt0時(shí)，方程式（）和（）給出精確的結(jié)果。換句話說，?1 是恒在任意橫截面上。因此σri,隨著σ1知道了，表示為：w=r(PiriPOrO)(12μ)+(PiPO)rirO(1+μ)Er(rri)2O22222第五篇：過程裝備與控制工程專業(yè)英語翻譯 17Reading Material 17Stress CategoriesThe various possible modes of failure which confront the pressure vessel designer are:(1)Excessive elastic deformation including elastic instability.(2)Excessive plastic deformation.(3)Brittle fracture.(4)Stress rupture/creep deformation(inelastic).(5)Plastic instabilityincremental collapse.(6)High strainlow cycle fatigue.(7)Stress corrosion.(8)Corrosion dealing with these various modes of failure, we assume that the designer has at his disposal a picture of the state of stress within the part in would be obtained either through calculation or measurements of the both mechanical and thermal stresses which could occur throughout the entire vessel during transient and steady state question one must ask is what do these numbers mean in relation to the adequacy of the design? Will they insure safe and satisfactory performance of a ponent? It is against these various failure modes that the pressure vessel designer must pare and interpret stress example, elastic deformation and elastic instability(buckling)cannot be controlled by imposing upper limits to the calculated stress must consider, in addition, the geometry and stiffness of a ponent as well as properties of the plastic deformation mode of failure can, on the other hand, be controlled by imposing limits on calculated stresses, but unlike the fatigue and stress corrosion modes of failure, 。綜合垂直dσdr方向上的力和不計(jì)高階的項(xiàng)，于是我們得到σEq—σr=r第二種關(guān)系可以表達(dá)為：σq=（1+μ）（12μ）[εq(1μ)+μ（εr+ε）]σr=Eσ1=（1+μ）（12μ）E[εr(1μ)+μ（ε(1μ)+μ（εq+ε+ε）]）]（1+μ）（12μ）[ε1qr.()與及把結(jié)果代入Eq.()得：dwdr+1dwrdr—wr=0Br方程的一個(gè)值為W=Ar+r=riatσ：w= — μrε1+= —pir= —poatr=roOEr(rri)r2(1μ2μ（）PiriPOrO）+rirO(1+2222μ)（PiPO）］ 當(dāng)W被求得，σ、圓柱的厚度可以表達(dá)為：rirOσq=PiriPOri+(PiPO)（rOr)riσr= —POriPiri+(PiPO)（r2OrirOr)riσr=徑向應(yīng)力σq=環(huán)向應(yīng)力Pi=內(nèi)部壓力PO=外部壓力ri=內(nèi)半徑rO=外半徑r=任意點(diǎn)的半徑、。接著要求助于Lame首先提出來的“厚殼”理論。第四篇：過程裝備與控制工程專業(yè)英語翻譯4Reading Material4Stresses in Cylindrical Shells due to Internal PressureThe classic equation for determining stress in a thin cylindrical shell subjected to pressure isobtained from of forces perpendicular to plane ABCD gives:PL ．2r =2σqLtorσqq=PrtWhereP=pressure,L=length of cylinder ,σThe strain εε=is defined as_2prr2prr=hoop stress ,r=radius, t=thicknessq2p(r+W)2prrr=qorεq=WrAlsoεdWdrThe radial deflection of a cylindrical shell subjected to internal pressure is obtained by substituting the quantity into Eq.().Hence for thin cylindersW=PrEt2Where W= radial deflection, E= modulus of elasticityEquations()and()give accurate results when r rt decreases,however , a more accurate expression is needed because the stress distribution through the thickness is not is then made to the “thick shell” theory first developed by derived equations are based on the forces and stresses shown in theory assumes that all shearing stresses are zero due to symmetry and a plane that is normal to the longitudinal axes before pressure is applied remains plane other words ,?1 is constant at any cross sectionA relationship between σrand σqcan be obtained by taking a freebody diagram ofring dr as shown in forces in the vertical direction and neglecting higherorde terms ,we then haveσ—σr=dσdrrqA second relationship is written asσ σr=q=E（1+μ）（12μ）E[εq(1μ)+μ（εr+ε）]σ1=（1+μ）（12μ）E[εr(1μ)+μ（ε(1μ)+μ（εq+ε+ε）]）]（1+μ）（12μ）[ε1qrSubstituting Eqs.()and()into the first t