深冷液體存貯與輸送的實(shí)現(xiàn)

1、Cryogenic Storage and DeliveryWhy it Works深冷液體存貯與輸送的實(shí)現(xiàn)Jan. 5th, 2012CHTRAMAT-EN-003(2012)Company ConfidentialOverview概述nGasses are stored as liquid for several reasons氣體之所以液化存貯lHigher storage density高存貯密度lEasier Delivery logistics容易輸送lEasier Pumping易泵輸送lUse of the refrigeration content制冷技術(shù)的使用1 VCS 1

2、500(9) 8X8 Racks (576) High Pressure CylindersCompany ConfidentialWhat a storage Tanks Does貯罐可以做到nStores the Liquid, keeping it cold.貯存液體,使其保持低溫nAllows for Refilling可重新充裝nMaintains Pressure保持壓力nAllows for Level Measurement保持液位nAllows for Withdrawal使用lGas applications氣體使用lLiquid Applications液體使用nProt

3、ects itself from over pressurization.防止罐體超壓Company ConfidentialUnderstanding a Liquefied Gas理解液化氣體nImportant fluid properties include重要的液體參數(shù)包括lPressure壓力lTemperature溫度lDensity密度lEnergy能量nThe relationship between these properties is fixed for a fluid. Knowing any two allows us to predict the rest.對(duì)任一

4、液體而言,這些參數(shù)之間的關(guān)系是確定的,任何兩個(gè)已知的參數(shù)都可以推導(dǎo)出其他的參數(shù).nThe least intuitive, but most influential is the energy of the fluid.最直接也是最有影響的參數(shù)是能量.nUnderstanding the Influence of energy on the fluid is critical to understand why cryogenic systems work the way they do.理解液體能量有助于理解深冷系統(tǒng)工作的原理nThermodynamics is the study of h

5、ow energy affects the state of a fluid.此處的熱力學(xué)是解釋能量如何影響液體狀態(tài)的學(xué)科nEnergy (heat) will move from one body to the next if there is a temperature difference between them. The higher the difference, the faster the energy is transferred. Energy is also introduced when work is done on the liquid. Anytime the l

6、iquid is transferred, there is an increase in the energy of the liquid.兩個(gè)物體之間存在溫差時(shí)即可產(chǎn)生傳熱. 溫差越大,傳熱越快.對(duì)液體做功也能產(chǎn)生能量. 輸送液體時(shí)液體的能量會(huì)增加.Company ConfidentialIntuitive Material Properties物質(zhì)特性參數(shù)Property特性Description描述Units單位Example of Influence on design設(shè)計(jì)相關(guān)示例Pressure壓力Force/Unit Area單位面積受力PSI, PSIA, PSIGPa, Mp

7、aInner Vessel Thickness內(nèi)容器壁厚Outer Vessel Thickness外容器壁厚Temperature溫度Response that an amount of material has based on the energy it is carrying表示物體冷熱程度Fahrenheit, Rankine 華氏度Celsius, Kelvin攝氏度Material Selection材料選擇Vaporizers汽化器PB Coils自增壓器Density密度Mass/Unit Volume單位體積的質(zhì)量Specific Volume = 1/Density#/F

8、t3#/Gal.Kg/literKg/NM3R/2T=PR/SaRColdest Recorded Temperature, AntarcticaCryogenic TemperatureDark Side of the MoonOxygen Liquifies at ambient pressuresNitrogen Liquifies at ambient pressuresHydrogen liquifies at ambient pressuresHelium Liquifies at ambient pressuresAbsolute zero, Theoretically no m

9、olecular motion-297 F-320 F-423 F-452 F-460 F-126 F-148 F-280 FWater Boils Hot Summer Day, PhoenixWater FreezesCold Winter Day, Minneapolis+110 F+32 F-20 F+212 FCompany ConfidentialHeat (Energy) Property能量參數(shù)Property特性Description描述Units單位Example of Influence on design設(shè)計(jì)相關(guān)示例Internal Energy內(nèi)能(U)Energy

10、measure that includes molecular energy at constant volume.物體在恒定體積下包括分子運(yùn)動(dòng)的能量總和dU/dT=CvBTU/lbJ/kgHold Time壓力保持時(shí)間(analysis where pressure changes within a control mass研究在恒定質(zhì)量下壓力變化)Enthalpy 焓(H)Energy measure that includes molecular energy and work energy at constant pressure.物體在恒壓下的能量和功的總和dH/dT=CpH=U+P

11、VBTU/lbJ/kgPB Coil sizing自增壓器計(jì)算Vaporizer Sizing汽化器計(jì)算NER Calculation蒸發(fā)率計(jì)算(analysis where mass changes within a control volume研究在恒定體積下質(zhì)量變化)Entropy熵(S)Energy measure that is used to measure lost work potential and energy efficiency.Tds=dU=PdVTds=dH-VdPBTU/lb-RJ/kg-KUsed in designing efficient liquefact

12、ion systems. Helpful in evaluating the energy added by pumps.Company ConfidentialPage 7名詞解釋nCryogenic 深冷lA branch of engineering that relates to the production and effects of very low temperature, usually -230F and colder.nHeat leak 熱泄漏nCavitation 氣穴lPartial or full loss of pump prime due to insuffi

13、cient subcooling or Net Positive Suction Head nDepressurization Flash LosslVaporization caused by reducing the gas phase pressure to something less than saturated vapor pressure of the liquid. Company ConfidentialPage 8nCondensation 冷凝lThe conversion of vapors into liquid by cooling the vapors.nEqui

14、librium 平衡lA state where the liquid and gas phases coexist a the same temperature and vapor pressure.nSaturation 飽和lA state where the liquid and gas phases coexist in equilibrium.名詞解釋Company ConfidentialPage 9nSubcooling 過(guò)冷度lRaising gas space pressure above the normal vapor pressure of a saturated l

15、iquid creating Net Positive Suction Head(NPSH).nStratification 分層lA vertical temperature gradient with colder product at the bottom and warmer product at the top.nEntrainment 霧沫lLiquid droplets carried along with a flowing gas stream.名詞解釋Company ConfidentialPage 10三相點(diǎn)n三相點(diǎn) triple pointl是指在熱力學(xué)里，可使一種物質(zhì)

16、三相（氣相，液相，固相）共存的一個(gè)溫度和壓力的數(shù)值l三相共存時(shí)具有固定的溫度和壓強(qiáng)l氦，是唯一沒(méi)有三相點(diǎn)的物質(zhì)l例：水的三相點(diǎn)在0.01（273.16K），611.73Pa l.LNG StationWater_boil.wmvCompany Confidential水的蒸發(fā)過(guò)程n開(kāi)始水的溫度：78 （25 .5）n飽和蒸汽壓：3.169x103Pan水開(kāi)始沸騰： 79 （26.1 ）n飽和蒸汽壓：3.3x103PaPage 11Company ConfidentialPage 12臨界點(diǎn)臨界點(diǎn)n臨界點(diǎn)臨界點(diǎn) critical point l一種熱力學(xué)狀態(tài)，此時(shí)在最高可能溫度下物質(zhì)的液態(tài)和氣態(tài)

17、可以平衡共存n臨界溫度臨界溫度 critical temperature l物質(zhì)處于臨界狀態(tài)時(shí)的溫度。 l物質(zhì)以液態(tài)形式出現(xiàn)的最高溫度。 l溫度不超過(guò)某一數(shù)值，對(duì)氣體進(jìn)行加壓，可以使氣體液化，而在該溫度以上，無(wú)論加多大壓力都不能使氣體液化，這個(gè)溫度叫該氣體的臨界溫度。在臨界溫度下，使氣體液化所必須的最小壓力叫臨界壓力。n臨界壓力臨界壓力 critical pressure l物質(zhì)處于臨界狀態(tài)時(shí)的壓力（壓強(qiáng)）。l在臨界溫度時(shí)使氣體液化所需要的最小壓力。 l液體在臨界溫度時(shí)的飽和蒸氣壓。Company ConfidentialPage 13飽和狀態(tài)、飽和蒸氣壓、飽和溫度n飽和狀態(tài) saturati

18、on condition l液體汽化時(shí)，其分子不斷從液體中逸出，同時(shí)也有分子從蒸氣中進(jìn)入液體，當(dāng)達(dá)到同一時(shí)間進(jìn)出液體的分子數(shù)相等并平衡時(shí)的狀態(tài)。n飽和蒸氣壓 saturated vapor pressure l在一定溫度下，與液體或固體處于相平衡的蒸氣所具有的壓力稱為飽和蒸氣壓。l同一物質(zhì)在不同溫度下有不同的蒸氣壓，并隨著溫度的升高而增大。n飽和溫度 saturation temperaturel是指 液體和蒸氣處于動(dòng)態(tài)平衡狀態(tài)即飽和狀態(tài)時(shí)所具有的溫度ts。l飽和狀態(tài)時(shí)，液體和蒸氣的溫度相等。l飽和溫度一定時(shí)，飽和壓力也一定；反之，飽和壓力一定時(shí)，飽和溫度也一定。l溫度升高，會(huì)在新的溫度下形成

19、新的動(dòng)態(tài)平衡狀態(tài)。物質(zhì)的某一飽和溫度必對(duì)應(yīng)于某一飽和壓力。Company ConfidentialPage 14蒸發(fā)、汽化、沸騰和沸點(diǎn)n汽化汽化 vaporization l物質(zhì)從液態(tài)轉(zhuǎn)變?yōu)槠麘B(tài)的過(guò)程n蒸發(fā)蒸發(fā) evaporationl物質(zhì)從液態(tài)轉(zhuǎn)化為氣態(tài)的相變過(guò)程n沸騰沸騰 boiling l在液體表面和內(nèi)部同時(shí)發(fā)生的劇烈汽化現(xiàn)象n沸點(diǎn)沸點(diǎn) boiling pointl液體沸騰的溫度n蒸發(fā)和沸騰的聯(lián)系蒸發(fā)和沸騰的聯(lián)系l它們都是液體汽化的方式，即都屬于汽化現(xiàn)象，液體在蒸發(fā)和沸騰的過(guò)程中，都需要吸收熱量。l.VCDNitrogen_boil.wmvCompany ConfidentialPage

20、 15沸點(diǎn)、沸騰和蒸發(fā)n蒸發(fā)和沸騰的區(qū)別蒸發(fā)和沸騰的區(qū)別l蒸發(fā)是液體在任何溫度下都能發(fā)生的汽化現(xiàn)象，而沸騰是液體在一定溫度（沸點(diǎn)）下，并繼續(xù)加熱，才能發(fā)生的汽化現(xiàn)象。 l蒸發(fā)是只在液體表面發(fā)生的緩慢的汽化現(xiàn)象，而沸騰是在液體表面和內(nèi)部同時(shí)發(fā)生的劇烈的汽化現(xiàn)象。 l蒸發(fā)時(shí)液體溫度會(huì)下降，而沸騰中液體溫度保持不變（在液體表面上壓強(qiáng)不改變的前提下）。 l影響蒸發(fā)速度的因素是：液體的表面積，液體的溫度，液體表面附近的空氣流速；影響沸點(diǎn)的因素是：液體表面上的氣壓，液體的純凈程度。 影響沸騰速度的因素：液體體積和原先的溫度 l沸騰時(shí)有氣泡產(chǎn)生，而蒸發(fā)時(shí)則無(wú)氣泡產(chǎn)生。 l蒸發(fā)的微觀本質(zhì)為：由于分子的熱運(yùn)動(dòng)，

21、使液體表面的分子離開(kāi)液體，進(jìn)入空氣中。 l蒸發(fā)在任何溫度都會(huì)進(jìn)行，只是溫度越高越快，反之越慢。而沸騰必須溫度在沸點(diǎn)，且繼續(xù)吸熱。 l沸騰的微觀本質(zhì)為：由于汽化劇烈產(chǎn)生了氣泡，不僅液體表面的分子要離開(kāi)液體，液體內(nèi)部氣泡壁上的分子也要離開(kāi)液體，進(jìn)入空氣中。沸騰現(xiàn)象中包含了蒸發(fā)現(xiàn)象，但蒸發(fā)現(xiàn)象卻不包括沸騰現(xiàn)象。Company ConfidentialPage 16汽化潛熱n汽化潛熱 latent heat of vaporization l單位質(zhì)量的液體轉(zhuǎn)變?yōu)橄嗤瑴囟鹊恼魵鈺r(shí)吸收的熱量稱為汽化潛熱，簡(jiǎn)稱汽化熱l它隨溫度升高而減小，因?yàn)樵谳^高溫度下液體分子具有較大能量，液相與氣相差別變小。l在臨界溫度

22、下，物質(zhì)處于臨界態(tài)，氣相與液相差別消失，汽化熱為零。Company ConfidentialPVT/PET Surface壓力/體積（能量）/溫度nThere is a relationship between the properties of a fluid that is known for each type of fluid. We can design equipment based on this relationship對(duì)任意一種特定流體，其特性之間都存在固定關(guān)系，可以利用其進(jìn)行設(shè)備設(shè)計(jì)nAny two properties will dictate the third. Th

23、is creates a three dimensional property relationship 任意兩個(gè)參數(shù)可以確定第三個(gè)，以此確定三者函數(shù)關(guān)系nThe physical state of the fluid is based on where we are on this surface relationship流體的物理狀態(tài)是基于它處于關(guān)系函數(shù)中的位置Company ConfidentialnThe most critical area of the surface is the vapor dome. In this region we define the transitio

24、n from liquid to gas.P-T曲線中關(guān)鍵區(qū)域是飽和區(qū)域（飽和液相線及飽和汽相線以下），此區(qū)域內(nèi)液體 汽化為氣體。nAbove the dome, the fluid acts in a predictable manner and follows a linear relationship between pressure and density.曲線以上，流體在壓力和密度之間存在線性關(guān)系nPure liquid is essentially incompressible due to pressure, yet its density will change with in

25、creasing energy純液體是不可壓縮的，但隨著能量的變化它的密度會(huì)產(chǎn)生變化。PVT/PET Surface壓力/體積（能量）/溫度Company ConfidentialCompany ConfidentialCompany ConfidentialSaturation/Equilibrium飽和/平衡nFluid that is on the dome space is said to be in equilibrium or saturated飽和區(qū)內(nèi)的流體處于飽和或平衡狀態(tài)nA saturated state is often further noted by the coin

26、cident corresponding pressure or temperature to this position.飽和狀態(tài)下壓力或溫度可以維持不變.nWhen Saturated a pressure, any reduction in pressure, or increase in heat will result in the fluid changing from liquid to vapor. Vaporization or boiling飽和壓力下，任何壓力的降低或能量的增加都導(dǎo)致液體的汽化（汽化或沸騰）nCommensurately any increase in p

27、ressure or reduction in heat will result in the fluid changing from vapor to liquid. Condensation相應(yīng)地，任何壓力的升高或能量的減少都會(huì)導(dǎo)致氣體的液化（冷凝）nA fluid that in liquid state and marginally away from the dome by virtue of excessive pressure is said to be sub-cooled. Such a liquid has capacity absorb heat and/or lose

28、pressure and still not begin to vaporize or boil液態(tài)的流體在增壓會(huì)形成過(guò)冷。它在吸熱并/或降壓的情況下并不汽化或沸騰。Company ConfidentialSaturation飽和Increasing Temperature增壓Increasing Pressure Required to Keep Molecules from being Liberated (Boiling )沸騰Increasing Density密度增加Increasing Heat Energy能量增加Sub-Cooled過(guò)冷Equilibrium平衡Boiling沸

29、騰Company ConfidentialStores the Liquid, keeping it cold液體存貯及保溫nHeat transfers slowly into the stored liquid熱量會(huì)緩慢傳導(dǎo)給液體nLiquid near the wall heats up before the internal liquid靠近筒壁的液體首先升溫nThe reduced density cause the liquid to migrate to the top of the liquid, separating and distributing the heat une

30、venly升溫后的液體密度降低,向上移動(dòng),導(dǎo)致了熱量傳遞的不均勻nThe same happens in the vapor side of the tank罐的氣相存在同樣現(xiàn)象nThis uneven distribution of the heat creates sub cool on the liquid and is called stratification熱量的不均勻分布導(dǎo)致液體的過(guò)冷,稱做分層nTo stratify, there needs to be isolation between the temperatures. Horizontal tanks will stra

31、tify less than vertical tanks. Small tanks less than large ones. Tanks in motion will not stratify at all.分層的形成需要溫度的不均勻不分布. 臥罐分層少于立罐;罐體積越大分層越明顯;移動(dòng)罐不分層HEATCompany ConfidentialAllows for Refilling重新充裝nAs the tank is likely attached to a use device, interrupting the use of a tank for filling is undesir

32、able, there is a need to maintain tank pressure while refilling罐總在使用當(dāng)中,為了充裝打斷使用是不可接受的.因此充裝時(shí)需要維持罐內(nèi)壓力nIntroduction of liquid to the tank will cause the vapor in the top to be compressed. This will raise the pressure充液時(shí)頂部液體汽化導(dǎo)致空間壓縮、壓力上升nIntroduction of liquid into the warm, stratified, vapor space will

33、 tend to remove heat from the vapor and in turn cause it to condense. This will reduce the pressure in the tank把液體注入暖的、分層的氣相空間將導(dǎo)致氣體的熱量傳到液體使之凝結(jié)。這將使罐的壓力降低。nHaving both a top and bottom fill valves allow for the tank to be connected to a use application and be filled without interruption. The filling o

34、perator will manipulate the top and bottom fill valve while monitoring the tank pressure.頂充和底充同時(shí)使用使得充裝時(shí)不用停止罐的使用。操作者可以監(jiān)控壓力，選擇使用頂充或底充。Fill Check (swing)Top/Bottom fill (globe-angle)Thermal Relief (non-code)Hose Drain(globe)Spray BaffleCompany ConfidentialMaintains Pressure壓力保持nIn order to increase pre

35、ssure, tanks are configured with a pressure building, or PB, circuit.貯罐配置PB來(lái)實(shí)現(xiàn)升壓nThe force of the weight of liquid is allowed to drive liquid out of the tank and through an ambient air heat exchanger. 液體自身的重量使液體流入熱交換器nThe liquid first absorbs heat until it is saturated at the tank pressure液體首先在貯罐壓力下

36、吸熱至飽和nContinued heating begins to boil the liquid繼續(xù)吸熱至沸騰nSome additional heating of the vapor will occur before the gas is returned to the top of the tank.氣體回到罐內(nèi)前將繼續(xù)吸收一部分熱量nThe more easily the tank is stratified , the more effective the PB system will work. Vertical tanks have the advantage of incre

37、ase liquid head (push) and more advantageous distribution of heat 液體分層越容易，PB效率越高nSome vapor may be reduced in volume once it enters the confines of the cold tank進(jìn)入冷罐后部分蒸汽的體積會(huì)變小.Thermal Relief (2, non-code)DP = Density X heightIsolation Valves (2, globe)PB Regulator(pressure reducing)PB CoilHeatCompa

38、ny ConfidentialPB Circuit增壓回路增壓回路nThe PB circuit is intended to replace the volume of liquid removed with gas at the same pressure增壓循環(huán)的目的是在同壓下用氣體取代減少的液體nOnly liquid head is available to drive the mass through the circuit只有液柱壓力能夠驅(qū)動(dòng)循環(huán)nLiquid side regulators deliver higher capacities but tend to oversh

39、oot on recovery液相調(diào)壓閥能夠提供更多的液體給氣相空間以補(bǔ)足失去的液體Company ConfidentialAllows for Level Measurement液位測(cè)量nThe same pressure that drives the PB also is used to drive a differential pressure gauge for estimating the level in the tank.驅(qū)動(dòng)增壓的壓力同樣能夠驅(qū)動(dòng)差壓式壓力計(jì)顯示貯罐內(nèi)的液位nThe gauge will show the level between the surface i

40、n the tank and the surface of liquid in the liquid phase line. This approximates the level in the tank表頭能夠顯示罐內(nèi)液面和液相管內(nèi)液面之間的差值，近似于罐內(nèi)的差值。Equalization Valve (needle)DP=Density X heightPhase line isolation(2, needle)Pressure GuageCompany ConfidentialAllows for Level Measurement液位測(cè)量nAbrupt changes in pres

41、sure will either expand or compress the vapor portion of the liquid phase line. This will in turn make the Differential pressure gauge vary.突然的壓力變化將會(huì)導(dǎo)致液相管內(nèi)蒸汽的膨脹或壓縮，這將導(dǎo)致差壓式壓力表的變化nOver time, heat leak into the liquid phase line will return the gauge to a normal indication. This however may take severa

42、l hours. Pressure changes that occur over minutes can result in misleading indications.隨著時(shí)間的變化，進(jìn)入液相管的熱量將使得表頭回到正常的指示。然后需要也許幾個(gè)小時(shí)，壓力變化將很快導(dǎo)致不正確的指示nA similar issue can occur if the equalization valve is left open for a period of time. The equalization valve should only be opened after the isolation valve

43、s are closed當(dāng)平衡閥打開(kāi)時(shí)，類似情況也會(huì)出現(xiàn)。只有隔離閥關(guān)閉時(shí)才能打開(kāi)平衡閥Equalization Valve (needle)DP=Density X heightPhase line isolation(2, needle)Pressure GuageCompany ConfidentialAllows for Withdrawal Liquid Applications液體使用nAs liquid is withdrawn, the vapor in the top of the tank will expand to accommodate the missing liq

44、uid volume.取液時(shí)，罐頂蒸汽將膨脹以充填液相空間nIf this continues until the pressure drops to the saturation pressure of the liquid, the liquid will begin to boil.壓力將一直降低到液體的飽和壓力，液體開(kāi)始沸騰nLiquid applications that are driven by cryogenic pumps are a special case. Inefficiencies in pumps will add heat to and reduce the p

45、ressure on the liquid that is in the pump. Such heat will boil the liquid in the pump causing the pump to stop working. Excessive boiling, or cavitation, in the pump can cause severe damage to the pump. Maintaining some sub-cool on the liquid is important for pump performance. The liquid must have c

46、apacity to absorb some pressure drop and heat addition without boiling.用低溫泵驅(qū)動(dòng)的液體使用情況有所不同，泵做功會(huì)把熱量帶到泵里的液體使之壓力降低。這些熱量將會(huì)使液體沸騰并使泵停止工作。過(guò)度的沸騰或者氣穴使泵損壞，保持一定的過(guò)冷對(duì)泵有利。液體應(yīng)該有一定的吸納壓降和熱量而不導(dǎo)致沸騰的能力。Company ConfidentialnTo maintain sub-cool, a PB system is employed. The amount of flow through he PB is very small. The

47、liquid through the PB is expanded from the liquid density to the vapor density. Typically the PB flow rate only needs to be about 5% of the liquid flow rate from the tank.使用增壓系統(tǒng)以維持過(guò)冷。通過(guò)增壓系統(tǒng)的流量極小，它從液體膨脹為氣體。一般而言通過(guò)增壓系統(tǒng)的流量?jī)H為液體使用流量的5%nA thermo-Siphon tank maintains sub-cool at the inlet of the pump by co

48、ntinuously flowing cold liquid from the bottom of the tank across the pump inlet and back to the bottom of the tank. This flow is induced by the inefficiency heat of the pump. As the heat warms the cold liquid, its density is reduced. This difference in density creates a small pressure difference an

49、d a convective flow. As long as the convective flow exceeds the pump speed, the tanks will keep a small amount of sub cool on the liquid from the liquid head of the tank. If the pump speed greatly exceeds this convective flow, a PB system may need to be employed.熱虹吸罐通過(guò)不斷地從罐底部抽取冷的液體通過(guò)泵入口并回到罐的底部來(lái)維持泵入口

50、的過(guò)冷。泵的做功產(chǎn)生熱量使流量降低。熱量使冷的液體加熱導(dǎo)致了液體密度的降低，密度的差異造成了極小的壓力差異和對(duì)流。由于這一對(duì)流速度大于泵的速度，罐將保持液體一定的過(guò)冷度。如果泵速大于過(guò)渡，則需要使用增壓系統(tǒng)。Allows for Withdrawal Liquid Applications液體使用Company ConfidentialAllows for Withdrawal Gas applications氣體使用nGas applications are those where the customer is going to use the product in gaseous for

51、m. This means that the cryogen is going to be vaporized to a gas before it reaches the application.氣體使用用于客戶要求使用氣態(tài)產(chǎn)品的場(chǎng)合，這意味著在使用前深冷液體應(yīng)該已經(jīng)蒸發(fā)成氣體。nThe liquid withdrawn needs to have its volume replaced as in the liquid withdrawal, or the pressure will drop and potentially disrupt the end user. 提液后突出部分應(yīng)被填

52、充，或意味著壓力將會(huì)降低并影響最終使用。nAlthough maintaining sub-cool is not critical, maintaining pressure for the end use application is. Here again the PB is used to maintain pressure.盡管維持過(guò)冷并不重要，但維持一定的壓力以確保最終應(yīng)用很重要。需要用增壓系統(tǒng)來(lái)維持壓力。. Company ConfidentialnA gas use application also allows us to withdraw from the vapor ph

53、ase of the tank if desired.如果有需要，同樣可能從氣相空間來(lái)提取氣體供使用。nDoing so creates the opportunity to quickly correct any over-pressure issues in the tank.如此，將有機(jī)會(huì)快速糾正罐內(nèi)的過(guò)高壓力。nThis circuit, called and economizer circuit, is controlled by a regulator that opens at a prescribed point typically above the PB set point

54、.這一循環(huán)被稱為經(jīng)濟(jì)回路，它由一個(gè)在設(shè)定壓力高于增壓開(kāi)啟壓力的調(diào)壓閥控制。nVapor is driven through the circuit by the liquid head generated in a dip tube that runs the length of the tank.蒸汽由液柱靜壓力驅(qū)動(dòng)通過(guò)回路，此回路為一根與罐體高度相同的下行的管路nWhen open, a mixture of liquid from the bottom and vapor from the top is drawn into the final vaporizer and to the

55、customer. Since they are using gas phase product, such a mixture is of no consequence to the customer. 當(dāng)回路開(kāi)啟時(shí)，從底部的液體和頂部的氣體混后后進(jìn)入汽化器并供給用戶。由于客戶最終使用的是氣體，因此氣液混合物對(duì)用戶沒(méi)有影響。Allows for Withdrawal Gas applications氣體使用Company ConfidentialGas-Use/PB氣體使用/增壓 Product to CustomerEconomizer Regulator(back pressure)Ec

56、onomizer Isolation(globe or swing check)Gas Use Valve(globe)Company ConfidentialGas-Use/Economizing氣體使用/經(jīng)濟(jì)回路Product to CustomerEconomizer Isolation(globe or swing check)Economizer Regulator(back pressure)DP = Density X heightGas Use Valve(globe)DPCompany ConfidentialP.B. Regulator增壓調(diào)壓閥Spring Chamber

57、SpringDiaphragmInletBiasing SpringoutletCompany ConfidentialEconomizer Regulator經(jīng)濟(jì)閥InletSpring ChamberSpringoutletDiaphragmCompany ConfidentialVaporizer Design汽化器HeatGas Use(globe)Temperature Control Valve(globe w/Thermo-well)Houseline Regulator(pressure reducing)Vaporizer Relief(usually coded)Vapor

58、izerFrom TankTo ApplicationnVaporizers should be designed to consider icing effect on efficiencies汽化器設(shè)計(jì)考慮結(jié)冰對(duì)效率的影響nExcessive gas velocities can create entrainment that will decrease exit gas temperatures過(guò)高氣體流速引起的夾帶會(huì)降低氣體溫度nExit gas temperatures can only “approach” ambient. (typically 20 degree F is us

59、ed)氣體溫度最高接近環(huán)境溫度Company ConfidentialProtects itself from over pressurization過(guò)壓保護(hù)nAs liquid absorbs heat, it expands. If there is no room for such expansion, the pressure will rise quickly in a tank.液體吸熱后會(huì)膨脹，如果沒(méi)有可膨脹的空間，壓力會(huì)急劇上升。nThe tanks have relief valves that will open in such an instance. Since the volumetric flow rate of the relief valve is many time larger than the volumetric growth rate, the pressure will quickly correct itself. In doing so, there will be liquid discharge from the relief valve. This is undesirable since it hard on the life of