課題換熱器畢業(yè)設(shè)計(jì)翻譯

1、<p>　　Comparison of Water-water Heat Exchanger Between Shell-and-tube Type and Plate Type</p><p>　　Abstract : </p><p>　　The closed-cycle cooling water system in the water of heat exchanger

2、selection, discusses in detail the shell and tube heat exchanger with plate structure and properties of technical and economic comparison of selection for the water of heat exchangers provide a reference. </p><

3、;p>　　Keywords: heat exchanger performance comparison </p><p>　　Power plants have been built from the domestic point of view, for the closed cycle cooling water system of the water of heat exchanger the

4、re are two types, one is shell and tube heat exchanger, and the other is a plate heat exchanger. Shell and tube heat exchanger is commonly used in heat exchangers form, in power plant design has been widely used, but som

5、e imported units in the domestic power plant, gas-steam combined cycle power plants and nuclear power plants have adopted multi-plate heat exc</p><p>　　A shell-and plate heat exchanger structure Introduction

6、 </p><p>　　(1) Shell and tube heat exchanger </p><p>　　Shell and tube heat exchanger is a former Marine Room, tubes, tube, after the composition of the water room. Tubes used to pump-type tubes,

7、 which consists of front and rear tube plate, baffle plate, rod, will be away from the tube, heat-exchange component. Rod and tube plate, split-flow plate using threaded connections, heat exchange tube and tube sheet wel

8、ding using sealed expansion joint increases. In the shell side of the water at the entrance to the tube bundle to set anti-scour plate, in or</p><p>　　(2) The plate heat exchanger </p><p>　　Plat

9、e heat exchanger is a corrugated-shaped by a group composed of parallel metal plates in the plate's four corners have the access hole, the side panels were clamped in a fixed plate with a connecting tube and activiti

10、es of pressed board framework, and used to clamp clamping bolts. The connecting pipe with the hole right in the channel plate, and with hot-swappable external piping connected to two kinds of liquids, heat transfer plate

11、s and the activities of pressed sheet hanging below the beam</p><p>　　There is a heat transfer plate itself has a specific shape and is solid tight gasket seal to prevent external leakage, and to heat exchan

12、ge of the two kinds of liquids by means alternately counter-current flow on heat transfer plates to another within the channel between the . Ripples on the plate not only improve the level of fluid turbulence, and the fo

13、rmation of many points of contact in order to withstand the normal operating pressures. Fluid flow, physical properties, pressure drop and temp</p><p>　　2. Heat exchanger design conditions </p><p&

14、gt;　　Heat exchanger should be designed to meet the maximum output power from the start-up to load when you run a variety of needs, and left a certain margin to ensure the heat exchanger at maximum load, the maximum water

15、 temperature and maximum thermal resistance when the dirt, in the prescribed maintenance cycle, able to complete the task given cooling. </p><p>　　With the introduction of domestic-type 300 MW coal-fired uni

16、ts, for example, the cooling device requires cooling water inlet temperature is not greater than 37.5 ℃ , from the cooling device out of the cooling water is heated before the maximum temperature is about 42.8 ℃ , its ba

17、sic parameters are as follows: </p><p>　　In addition to the cooling water salt water </p><p>　　Design pressure 1.0 MPa </p><p>　　Flow 1800 m

18、3 / h </p><p>　　Out of water temperature 42.8/37.5 </p><p>　　Pressure drop of ~ 0.06 MPa </p><p>　　Cooling water Seawater (seawater and river wa

19、ter alternately change) </p><p>　　Design pressure 0.5 MPa </p><p>　　Inlet temperature 33 ℃ </p><p>　　Water temperature </p><p>　　Circulatin

20、g water </p><p>　　Drop of pressure 0.05 ~ 0.06 MPa </p><p>　　3.Shell and plate heat exchanger in comparison </p><p>　　3.1 Comparison of design parameters </p>&

21、lt;p>　　According to the design of heat exchanger, respectively, made the following three conditions of the program: </p><p>　　Program 1:two 100% capacity, Tube shell heat exchanger </p><p>　　

22、Program 2:two 100% capacity plate heat exchanger </p><p>　　Program 3:three 50% capacity plate heat exchangers </p><p>　　Parameters of the program in Table 1. </p><p>　　Table 1.The d

23、esign parameters of the scheme of heat exchanger</p><p>　　3.2 The open-cycle cooling water (water of the cooling water side heat exchanger) system, equipment selection Comparison </p><p>　　Accor

24、ding to shell and tube and plate heat exchanger and cooling of different structural forms of water, need to choose a different electric filter and the open-cycle cooling water pumps, shown in Table 2. </p><p&g

25、t;　　Table 2.The filter and pump parameters of each scheme selection</p><p>　　3.3 Comparison of flow and heat transfer design </p><p>　　Shell and tube heat exchanger heat exchanger tubes are the

26、basic building blocks, which has in the pipe flow of a fluid and through the pipe apart from the provision of heat transfer between a fluid surface. According to both sides of the fluid nature of pipe materials, will hav

27、e a corrosive, water quality, poor water on the pipe flow, water quality, a good addition to brine on the shell side of the tube, so only use seawater corrosion-resistant tubes titanium tube, while cleaning dirt is more

28、c</p><p>　　Plate heat exchanger cooling water and cooling water have been on both sides of convection in the corrugated board, corrugated chevron corrugated using these heat transfer plates of corrugated bia

29、s, that is adjacent heat transfer plate has the same tilt angle but in a different direction ripple. Cross-sectional area along the flow direction is constant, but because of the ever-changing flow direction resulted in

30、changes in shape of flow channel, which leads to turbulence. The general heat transf</p><p>　　3.4 Comparison of heat transfer coefficient </p><p>　　Tube shell heat exchanger, a tube of fluid pas

31、sing through the lateral wall with the pipe flow of another fluid heat exchanger, each vertical cross-flow, the heat transfer coefficient is generally 1000 ~ 3000 w / (m2.k) . </p><p>　　Plate heat exchanger,

32、 cooling water, cooling water side by side with the uniform turbulent flow, two kinds of reverse flow of fluid, due to the role of ripples caused by turbulence, resulting in a high heat transfer rate, high resistance to

33、pressure drop and high shear stress field, which will led to the formation of inhibiting fouling in the heat transfer surface. The heat transfer coefficient is generally 3500 ~ 5500 w / (m2.k), this can save heat exchang

34、er heat transfer area. </p><p>　　3.5 Comparison of temperature difference </p><p>　　Shell and tube heat exchanger terminal temperature difference (ie, cooling water inlet temperature and the coo

35、ling water outlet temperature difference is) for about 5 ℃ . </p><p>　　Plate heat exchanger, because of its structural features can be economically achieved as low as 1 ℃ of temperature difference. </p>

36、;<p>　　3.6 Comparison of cooling water </p><p>　　Shell and tube heat exchanger cooling water and is generally the ratio of the cooling water is 1.2 ~ 2.5:1. </p><p>　　Plate heat exchanger

37、, due to two kinds of media flow path is basically the same heat transfer efficiency and high, plate heat exchangers can greatly reduce the amount of cooling water, cooling water and is generally the ratio of the cooling

38、 water of 0.8 ~ 1.1:1, so that Pipeline valves and pumps can reduce the running costs of the installation. </p><p>　　3.7 Comparison of installation and maintenance </p><p>　　Plate heat exchanger

39、 with small size and light weight characteristics, easy maintenance, without lifting set up maintenance facilities, and therefore less installation area. The artificial maintenance of plate heat exchanger including the f

40、olding machine to open, using spray guns and brushes clean plates and gaskets, inspection plates and gaskets, if necessary, replacement plates and gaskets. Plate heat exchangers to clean an annual general meeting, and wh

41、ether or not the actual needs should be </p><p>　　Shell and tube heat exchanger tube bundle is composed of its own weight were relatively large in size, in the maintenance pumping tube bundle when the need t

42、o stay out as long as the distance, it covers an area of more, with the necessary lifting needed to overhaul facilities. Shell and tube heat exchanger design life is generally 30 years, overhaul cycle, four years, when t

43、he heat exchanger leakage occurs, (which may be between the tube and tube sheet caused by leaking or broken pipe leakage) c</p><p>　　4. heat exchangers in the domestic power plant operation </p><p

44、>　　(1) Huaneng Yueyang Power Plant's two units 362 MW unit, the British manufacturer, plate heat exchanger is supplied complete with the host. Plant is located along the Yangtse, recycled water for the Yangtze Riv

45、er, where the Yangtze River water is characterized by coarse less sand and more plants and more of this recycled water into the steam room before the set up filters to deal with three plants and so on, but according to p

46、lant reflection of plate heat exchangers easily blocked, because the r</p><p>　　(2) Shanghai Wujing Power Plant 6 project hosts the Shanghai production of 300 MW of imported type unit, the unit closed coolin

47、g water systems, heat exchanger shell and tube water of the cooling water from the circulating water system supply, recycled water to take The Huangpu River's water, water, garbage, debris more, so water of heat exch

48、anger entrance to set up two open-rotary filter, 11 aircraft fitted with the original design of the filter for the imported equipment, filter pore size 3 ~ 4</p><p>　　Analysis was mainly due to small pore si

49、ze filters, filters in the structure design is not suited to China's water quality. To address the above issues, adopted a new electric automatic backwash filters, filter pore size of ψ 6 mm in good condition after t

50、he operation, not to have been blocked. </p><p>　　Early Chinese production of the 300 MW coal-fired units are mostly closed cooling water system chosen shell and tube water of heat exchanger operation are be

51、tter. In recent years, because of technological advances in design optimization needs, shell and tube exchanger Shui covers an area of large maintenance facilities in the main disadvantage of large plant layout optimizat

52、ion is even more prominent in a number of circulating water system for the secondary cooling The crew in the water, taking </p><p>　　5 .technical and economic analysis </p><p>　　With the introdu

53、ction of domestic-type 300 MW units, for example, under the water of heat exchanger design conditions and closed cycle cooling water system requirements, shell and tube and plate manufacturers made an initial offer, resp

54、ectively, other major auxiliary equipment is valued comparisons shown in Table 3. </p><p>　　Table 3.Comparison of three schemes of investment</p><p>　　Plate heat exchanger using imported equipme

55、nt, and its offer when the offer is being made according to the exchange rate converted into yuan, and only consider the value-added tax. The above table does not include maintenance and overhaul costs, its difficult to

56、estimate out, only qualitative analysis, for shell and tube heat exchangers include water-room, dirt handling of leak when plugging costs. Pairs of plate heat exchangers including plate cleaning and gasket replacement, b

57、ecause it is less</p><p>　　6. Conclusion </p><p>　　Through the shell and tube and plate heat exchanger comparisons can be drawn the following conclusions: plate heat exchanger, heat transfer, he

58、at transfer efficiency, small size and light weight in the disassembly, when the cooling water better, it is a kinds of ideal heat exchanger device. But for a large number of cooling water, sand, dirt, plants and so on e

59、xist, filters can not function effectively, it is easy to plug, resulting in frequent cleaning, affecting the safe operation of unit. </p><p>　　管殼式與板式水水換熱器的比較分析</p><p><b>　　摘要 : </b>

60、</p><p>　　通過(guò)閉式循環(huán)冷卻水系統(tǒng)中水水換熱器的選型,詳細(xì)論述了管殼式與板式換熱器的結(jié)構(gòu)性能技術(shù)經(jīng)濟(jì)比較,為水水換熱器的選型提供參考。</p><p>　　關(guān)鍵詞:換熱器;性能;比較</p><p>　　從國(guó)內(nèi)已建發(fā)電廠來(lái)看,用于閉式循環(huán)冷卻水系統(tǒng)的水水換熱器有兩類,一類是管殼熱換器,另一類是板式換熱器。管殼換熱器是常用的換熱器形式,在電廠設(shè)計(jì)中已得到了廣

61、泛的應(yīng)用,而在國(guó)內(nèi)一些進(jìn)口機(jī)組的電廠、燃?xì)庹羝?lián)合循環(huán)電廠和核電站多有采用板式換熱器。由于板式換熱器緊湊、重量輕、高傳熱效率,人們對(duì)它的興趣日益增長(zhǎng)。本文針對(duì)管殼式及板式換熱器二種型式進(jìn)行比較,并提出選型參考意見(jiàn)。</p><p>　　管殼式及板式換熱器結(jié)構(gòu)簡(jiǎn)介</p><p><b>　　管殼式換熱器</b></p><p>　　管殼式換熱器

62、是由前水室、管束、筒體、后水室等組成。管束采用可抽式管束,它由前后管板、折流板、拉桿、定距管、換熱管組成。拉桿與管板、拆流板采用絲扣連接,換熱管與管板采用脹接加密封焊。在殼側(cè)水入口處的管束上設(shè)置防沖板,以防止被冷卻水直接沖刷換熱管。為了減少管束裝入或抽出筒體時(shí)的摩擦力,在管束上設(shè)有滑軌。為了檢查清理室中垃圾、泥沙及管子的堵塞等,在前后水室端蓋上設(shè)有檢查孔。為了監(jiān)視水水換熱器的運(yùn)行情況,在被冷卻水側(cè)(除鹽水側(cè))及冷卻水側(cè)(海水側(cè))進(jìn)出口都

63、設(shè)置溫度和壓力測(cè)點(diǎn),此外還設(shè)有排氣和放水接口等。</p><p><b>　　板式換熱器</b></p><p>　　板式換熱器是由一組波紋形的平行金屬板構(gòu)成的,在板片的4個(gè)拐角處都有通道孔,板被夾緊在一個(gè)側(cè)面附有連接管的固定板和活動(dòng)壓緊板的框架中,并用夾緊螺栓加以?shī)A緊。這些連接管同板上的通道孔對(duì)中,并與熱交換的兩種液體的外部管路相連,傳熱板和活動(dòng)壓緊板懸掛在頂部承載

64、梁的下面并由底部橫梁使其對(duì)準(zhǔn)定位。傳熱板本身是有其有特定形狀并被固緊的墊片密封,以防止外部泄漏,并把熱交換的兩種液體按逆流方式交替地流過(guò)另一對(duì)傳熱板之間的通道內(nèi)。板片上的波紋不但提高流體的湍流程度,并且形成許多接觸點(diǎn),以承受正常的運(yùn)行壓力。流體的流量、物理性質(zhì),壓降和溫度差決定了板片的數(shù)目和尺寸。</p><p><b>　　換熱器設(shè)計(jì)條件</b></p><p>　

65、　換熱器設(shè)計(jì)應(yīng)滿足電廠從起動(dòng)到最大出力時(shí)各種負(fù)荷下的運(yùn)行需要,并留有一定的裕量,保證換熱器在最大負(fù)荷、最高進(jìn)水溫度和最大污垢熱阻時(shí),在規(guī)定的檢修周期內(nèi),仍能完成給定的冷卻任務(wù)。以國(guó)產(chǎn)引進(jìn)型300 MW燃煤機(jī)組為例,各冷卻設(shè)備要求冷卻水進(jìn)水溫度不大于37.5℃ ,從冷卻設(shè)備出來(lái)被加熱過(guò)的冷卻水最高溫度約為42.8℃ ,其基本參數(shù)如下:</p><p>　　被冷卻水 除鹽水</p

66、><p>　　設(shè)計(jì)壓力 1.0 MPa</p><p>　　流量 1800 m3/h</p><p>　　進(jìn)出水溫度 42.8/37.5</p><p>　　壓降 ～0.06 MPa</p>&

67、lt;p>　　冷卻水 海水(海水與河水交替變化)</p><p>　　設(shè)計(jì)壓力 0.5 MPa </p><p>　　進(jìn)水溫度 33℃</p><p><b>　　出水溫度</b></p><p><b>　　循環(huán)水

68、量</b></p><p>　　壓降 0.05～0.06 MPa</p><p>　　管殼式及板式換熱器的比較</p><p><b>　　3.1設(shè)計(jì)參數(shù)比較</b></p><p>　　根據(jù)換熱器的設(shè)計(jì)條件分別作了如下3個(gè)方案:</p><p>

69、;　　方案1: 2臺(tái)100%容量的管殼式換熱器</p><p>　　方案2: 2臺(tái)100%容量的板式換熱器</p><p>　　方案3: 3臺(tái)50%容量的板式換熱器</p><p>　　各方案的參數(shù)見(jiàn)表1。</p><p>　　表1各方案換熱器的設(shè)計(jì)參數(shù)</p><p>　　3.2開(kāi)式循環(huán)冷卻水(水水換熱器冷卻水側(cè))系

70、統(tǒng)設(shè)備選擇比較</p><p>　　根據(jù)管殼式及板式換熱器的不同結(jié)構(gòu)形式和冷卻水量,需選擇不同的電動(dòng)濾網(wǎng)和開(kāi)式循環(huán)冷卻水泵,詳見(jiàn)表2。</p><p>　　表2各方案選擇的濾網(wǎng)與水泵參數(shù)</p><p>　　3.3 流動(dòng)傳熱設(shè)計(jì)比較　　管殼式換熱器的管子是換熱器的基本構(gòu)件，它為在管內(nèi)流過(guò)一種流體和穿越管外的另一種流體之間提供傳熱面。根據(jù)兩側(cè)流體的性質(zhì)決定管子材料

71、，將具有腐蝕性，水質(zhì)差的海水放在管內(nèi)流動(dòng)，水質(zhì)較好的除鹽水放在管子外殼側(cè)，這樣管子只需采用耐海水腐蝕的鈦管，同時(shí)清洗污垢較為方便，管徑從傳熱流體力學(xué)角度考慮，在給定殼體內(nèi)使用小直徑管子，可以得到更大的表面密度，但大多數(shù)流體會(huì)在管子表面上沉積污垢層，尤其管內(nèi)冷卻水水質(zhì)較差，泥沙和污物及海生物的存在，都可能會(huì)在管壁上形成沉積物，將傳熱惡化并使定期的清洗工作成為必要，管子清洗限制管徑最小約為20 mm，鈦管一般采Φ25 mm，對(duì)給定的流體，污

72、垢形成主要受管壁溫度和流速的影響，為得到合理的維修周期，管內(nèi)側(cè)水的流速應(yīng)在2 m／s左右（視允許壓降的要求）。由于一般冷卻水選用海水、河水等，較易引起結(jié)垢，對(duì)管殼式換熱器，應(yīng)根據(jù)水質(zhì)含沙量情況需設(shè)置膠球清洗裝置進(jìn)行定期清洗?！　“迨綋Q熱器的冷卻水和被冷卻水在波紋板的兩側(cè)對(duì)流，波紋采用人字形波紋，這些傳熱板的波紋斜交，即在相鄰的傳熱板上具有傾斜角相同而方向不同的波紋。沿流動(dòng)方向橫截面積是恒定的，但</p><p>

73、;　　板式換熱器中，冷卻水側(cè)與被冷卻水側(cè)流動(dòng)均勻湍流，兩種流體逆向流動(dòng)，由于波紋的作用引起湍流，從而產(chǎn)生高傳熱率，高阻力壓降以及高切應(yīng)力場(chǎng)，這將導(dǎo)致抑制污垢在傳熱面上形成。其傳熱系數(shù)一般為3500～5500 w／（m2．k），由此，可節(jié)省換熱器的換熱面積。</p><p>　　3.5 端差比較　　管殼式換熱器傳熱端差（即冷卻水進(jìn)口溫度和被冷卻水出口溫度差）為5℃左右。 板式換熱器由于它的結(jié)構(gòu)特點(diǎn)可以經(jīng)

74、濟(jì)地做到低至1℃的端差。 3.6 冷卻水量比較 管殼式換熱器一般冷卻水量和被冷卻水量之比為1．2～2．5∶1。 板式換熱器，由于2種介質(zhì)流道基本相同且傳熱效率高，因此板式換熱器可大大降低冷卻水量，一般冷卻水量和被冷卻水量之比為0．8～1．1∶1，這樣可以降低管道閥門(mén)和泵的安裝運(yùn)行費(fèi)用。 3.7 安裝檢修的比較 板式換熱器具有體積小，重量輕的特點(diǎn)，檢修方便，不需設(shè)檢修起吊設(shè)施，故安裝占地較少。板

75、式換熱器的人工維護(hù)包括將整機(jī)折開(kāi)，用噴水槍和刷子清洗板和墊片，檢查板片和墊片，如有必要，更換板片和墊片。板式換熱器一般每年要清洗1次，并且無(wú)論是否實(shí)際需要都要做。當(dāng)應(yīng)用河水、海水等水質(zhì)較差的冷卻水時(shí)，由于泥沙和污物的存在，以及微生物的快速生長(zhǎng)有引起表面污染和堵塞的危險(xiǎn)。在國(guó)外，應(yīng)用河水作冷卻水時(shí)，清洗頻率很高，平均每年3．3次?！　」軞な綋Q熱器是由管束組成，自身重量體積都較大，在檢修抽管時(shí)需要留出管束一樣長(zhǎng)的距離，故</p>

76、;<p>　　表3三方案的投資比較</p><p>　　板式換熱器采用進(jìn)口設(shè)備，它的報(bào)價(jià)已按報(bào)價(jià)時(shí)的匯率折算成人民幣，并只考慮了增值稅。上表中未包括維護(hù)和檢修費(fèi)用，因其較難估出，只能定性分析，對(duì)于管殼式換熱器主要包括水室里污物的處理，發(fā)生泄漏時(shí)進(jìn)行堵管的費(fèi)用。對(duì)板式換熱器包括板片的清洗和墊片更換，因?yàn)樗那逑创螖?shù)較管殼式多及墊片使用2～3年后需要更換，故板式換熱器的檢修維護(hù)費(fèi)用要高。從以上比較可以看