EFFECT OF MAGNETIZATION OF WATER ON INDUCTION TIME AND GROWTH PERIOD OF NATURAL GAS HYDRATE

.第54卷增刊化工学Vol. 54 Suppl.2003年12月Journal of Chemical Industry and Engineering (China)December 2003EFFECT OF MAGNETIZATION OF WATER ONINDUCTION TIME AND GROWTH PERIODOF NATURAL GAS HYDRATEKUANG Li and FAN Shuanshi(Guangzhou Institue of Energy Conversion , Chinese Academy of Sciences , Guangzhou 510070，Guangdong, China)Abstract The effect of diluted solution' s magnetization on induction time and growth period of natural gashydrate (NGH) has been investigated in quiescent reaction system at pressure of 4. 5 MPa and temperatureof 274 K with SDS as surfactant, by using volume fixed and pressure falling method. Experimental resultsshow that magnetization will have effect on the induction time of NGH. After magnetization with magneticfield intensity of 0.33 T, the induction time of NGH has been reduced to 47 min (average) from 99 min(average) in which there is no magnetization. On the other hand, the induction time has been prolongedafter magnetization of the diluted solution with magnetic field intensity of0.05 T, 0.11 T, 0.22 T, 0.44T. Especially with magnetic field intensity of 0. 11 T, the induction time had even been prolonged to 431min (average). The effect of magnetization on the growth period of NGH has not been found at theexperimental condition.Keywords natural gas hydrate, magnetization, growth, induction timestorage technology is also safe with its low storageINTRODUCTIONpressure-3]. But there are three problemns that needNatural gas hydrate (NGH) as a kind of .to be solved; (a) the growth rate of NGH is verypotential strategic energy is distributed abroad onslow, (b) the NGH may contain a large quantitythe seabed and permafrost where condition permit.of water，(c) the NGH need to be separated andIt is hope to use NGH as a substitute for coal andtransported after forming.The growth rate ofoil which will be exhausted in the near futurel1.2] ,NGH in quiescent reaction system is very slow. .because its energy storage density is high and thereThere will be a period of induction time in theis not any residue left after burning. The researchreaction. It will depend on the experimentalabout NGH develops quickly in many areas such ascondition that how long the induction time will be.At first, it will perform a film at the water gasenergy, environment protection, etc.It has many advantages that natural gasinterface. To continue the reaction, water and gashydrate is used to storage and transport naturalcannot but diffuse through this film, so the growthgas. Natural gas hydrate might contain 180rate of NGH is bound up with the diffuse rate ofvolumes (at standard pressure and temperature) ofwater and gas. It might greatly improve thenatural gas per volume hydrate. This kind ofgrowth rate of NGH to add stir to the system. Butit will cost much energy and make the hydratecontain中国煤化工same time, theCoresponding author: Prof. FAN Shuanshi. E - mail:addictihydrate@ms. giec. ac. cnMHCNMHded. It may adFoundation item: supported by the National Natural Sciencethe cost oI equlpment ana maintenance.Foundation of China (No, 50176051) and the State Key DevelopmentKalogerakis et al has found that some kind ofProgram for Basic Research of China (Na. 2000263060.surfactant may enhance the growth rate of NGH,●82.化工学报December 2003or even alter the mechanism of growth. Which wasInstitute of Spaceflight Industry Company. Thalready shown in many papers4.5]. The effect ofmagnetization apparatus with adjustable magneticoutfield including sound field and magnetic field onfield intensity range from 0 to 0.5 T andthe induction time and growth period of gasmagnetization distance of 95 mm was made byhydrate is a new subject. Liu Yonghong and LiuBaotou Yuanci Technology Company.AgilentYong have tried this area5.,n]. They have studied(34970A) data gather was used to gather thethe effect of ultrasonic and static magnetic field onexperimental' data. A 20 MPa pressure gauge and athe growth and decomposition of refrigerant0.1 MPa vacuum gauge accurate to 0.25% of fullhydrate. The research of Liu Yong showed thatscale was made by Xi' an Gauge Company.the induction time of refrigerant hydrate could be1.2 Experimental materialreduced from 9 h to about 40 min. The research toNanHai Guicheng Haowen Gas Companyapply ultrasonic and magnetic field is in progress insupplied the natural gas with purity of 99. 9%，Itmany areas like agriculture planting, medical care,consists of 91. 98% methane, 5. 06% ethane andscale preventing, metallurgy, sewage treatment,2. 96% propane ( mol component) . Surfactantoil exploitation, material synthesizing, etc. Water(SDS) with purity of 98% was supplied bysystem will alter in its structure and charactersGuangzhou Chemical Reagent Company. We madeincluding optics character, electron character,distilled water ourselves.hydration of ion， superficial tension, etc after.3 Experimental procedure (see Fig. 1)magnetization[8- 10]. We have studied the effect ofStep 1: rinse the cell and give it airing, fix it,magnetization of diluted solution on the inductioncheck the experimental equipment, assure that alltime and growth period.parts are in order. Turn off valve 5, 7，8, 10,1 EXPERIMENT11 and pressure adjuster while other valves areturned on. Step 2: turn on the bath and data1.1 Experimental equipmentgather, set the temperature condition and begin toThe experimental equipment consists of cell,record the experimental data. Turn on valve 7,bath，temperaturesensor, pressuresensor ,pressure adjuster, vacum pump，magnetizationvacuum pump 15. The vacuum gauge 14 andpressure sensor 4 can indicate the pressure of theapparatus, data gather, pressure gauge, vacuumgauge, digital camera, etc. The cell with volumesystem. We can also know the temperature of theof 196 ml is made of stainless steel and can resistsystem by temperature sensor 3. Step 3: when thepressure of 20 MPa .It has a release valve and acell lid that can be opened to observe the hydrate[e贸南00and take photos. The cell and the pressure adjuster(YT-5) were made by Jiangsu Hai' an InstrumentCompany of Oil Research. The water bath(DC1006) which can control the temperature of画1:system range from一10 C to 100 C and accurateto士0.05 C was made by Ningbo TianhengFig. 1 Schematic diagram of experimental equipmentInstrument Company. The temperature of the cell-0ol。2- hath: 3- tomnerature sensor;was monitored with platinum resistance (Pt100)中国煤化工,9, 10, 11- valve，probes accurate to士0.1 K .The pressure sensorYHC N M H Gssure gauge;4- vacum gauge; 15- - vacuum pump;(SPTA-10) range from 0 to 10 MPa and accurate16- pressure adjuster; 17- gas cylinderto 0.187% of full scale was made by No. 702Vol. 54 Suppl.Journal of Chemical Industry and Engineering (China)temperature and pressure are consistent withrepeat times of magnetization is 10. The dilutedexperimental require (274 K)，turn off valve 6,solution will be injected into the cell right awayturn on valve 5, so 50 ml diluted solution (SDS)after magnetization. The magnetic field intensitycan be injected into the cell. The operation can beof magnetization which was used in experiment isachieved with buret accurate to 0. 1 ml. Turn off0 T，0.05 T, 0.11 T，0.22 T, 0.33 T,valve 5 after rejection. Step 4: when the0.44 T.temperature is consistent with the experimental2 RESULTS AND DISCUSSIONrequire again, turn off valve 7, turn on valve 8,shut off the vacum pump 15. Turn on valve 6,The original experimental data is the pressure10，11，pressure adjuster 16 orderly, begin toand temperature of the system in the reactioninfuse the cell with natural gas, we can monitorprocess (Fig. 2) . We can get the induction time t;the pressure of system by pressure gauge 13 duringand growth period tg at different magnetic fieldthe process. When the gauge reading achieved 4. 50intensity (as Fig.2 and Fig. 3 which is also tabledMPa，turn off valve 10，11 and pressure adjusteras Table 1 and Table 2) by time curve of pressure16. At this time, the cell is occluded. It takes atand temperature. Each experiment repeated 4most 30 seconds to complete the infusion of gas.times. We can get average induction time ti andWhen the induction time passed, the dilutedaverage growth period tag (Fig. 3 and Fig. 4).solution may react with the infused natural gas and2.1 Efect of magnetization on the induction timeform natural gas hydrate at experimentalHydrate formation consists of dissolution ofconditions. Because the forming of NGH willgases in liquids, induction time, growth period.consume large quantities of natural gas and releaseThere are two kind of definition about theheat，pressure in the cell will descend andinduction time usully11,12J 。In this paper, itemperature will rise. To some extend the reactionmeans period of time from the complete of thewill halt. Step 5: when the pressure signal do notinfusion of gas to a point in which pressure of thealter any more in 60 min, turn off valve 6 on thesystem begin to decrease rapidly (at the samecell, discharge the cell, turn on valve 5 to releasetime, the temperature of systembegan togas from the cell. As hydrate will notincrease).' The growth period means a period ofdecomposition completely right away, we can opentime from the complete of the induction time to athe lid to observe and take photos. Step 6: cleanpoint in which pressure of the system will notup all parts of experimental equipment，turn offdecrease obviously ( the pressure signal will notdata gather and bath and analyse the data. Preparechange in 60 min).for the next experiment.inductiontimeDistilled water that was used to confectdiluted solution was quantified by electron scale(BS2000S) accurate to 0.01 g. Surfactant wasg 25-- Pessuresquantified by analysis scale ( TG328A) accurate to0.1 mg. All the experiments are achieved atpressure of 4. 50 MPa and temperature of 274 K2-2with no stir. The concentration of surfactant中国煤化工向w2(SDS) is 200 mg●kg~'. There is not any variety[HCNMHGin condition of magnetization such as velocity ofFig.2" Pressure and temperature duringdiluted solution and repeat time of magnetization.the reaction processThe velocity of magnetization is 1.6 m●sI',(Magnetic field intensity=0. 44 T)●84●化工学December 2003Table 1 Induction time of the reaction after magnetization at diferent magnetic field intensity (p= 4.50 MPa,T=274 K)Magnetic fieldInduction time 1Induction time 2Induction time 3Induction time 4Average inductionintensity/T/minmintime/ min74.561.5139. 1124.299. 8250.05306. 2105. 4113. 8231. 4189. 20.11470. 6517. 6452. 6282. 1430. 7250.22126202.5236. 7319.8221. 250.3335. 654.293.74.847.0750.44.82.8221.130.894. 6107. 325Table 2 Growth period of NGH after magnetization at dfferent magnetic field intensity (p= 4.50 MPa,T=274 K)Growth period 1Growth period 2Growth period 3Growth period 4Average growth/ minperiod/ min157.9152. 1257198. 4191. 35386. 5212.7219. 8561345568. 7618.853.5374. 1529. 5250. 22201.1295. 3319.1401. 5304. 25139.4159. 4178.4120.149. 0250.44196323.9221204. 2236. 525It showed in Fig.2 that the drop of the240▲Growth perodofCNGHpressure curve and raise of temperature curve is∞0士Averege gow peidofNGHp-4.50MPa_200invisible during the induction time. It is close toT= 274KF 60horizontal line. But the pressure will drop rapidly1201fter the induction time, while the temperaturewill rise indicating its high reaction rate. It will:1↑islow down gradually in about 20 min.Thepressure and temperature curve will be close to03 04 a:horizontal line again.Magnetictield nensty/TFig.4 Growth period of NGH after magnetization▲Inductiontimeion tmeat different magnetic field intensityp=450 MraicnteT=274Kincrease of magnetic field intensity the inductiontime increase from 47.1 min to 107.3 min. Theexperimental results do not show the best value ofmagnetic field intensity.2.2 The effect of diluted solution's magnetization203 24 ason the growth periodMagneic fild itersly/TMagnetization of diluted solution will not haveFig. 3 Induction time of the reaction afterevident effect on the growth period of NGH at themagnetization at different magnetic field intensityexperimental conditions. The growth period curveMagnetization with different magnetic fieldof different magnetic field intensity is flat contrastintensity may have different effect on the inductionto the induction time curve. At first, the growthtime of NGH. At first, at the range from 0 to 0.33period prolonged in a sort with the increase ofT，with the increase of the magnetic fieldma中国煤化工shorten at the rangeintensity, the induction time increase from 99. 8fr(|YHC N M H Gwth period prolongedmin to 430. 7 min, and then decrease to 47. 1 min.with the increase of magnetic field intensity rangeAt the range of 0.33 T to 0.44 T，with the from 0.22 T to0.44 T.Vol. 54 Suppl.Journal of Chemical Industry and Engineering (China)●85●3 Rogers R E，Zhong Y. Feasibility of Storing Natural Gas in3 CONCLUSIONSHydrates Commerially. In; Second international symposiumon gas hydrates, Toulouse, 843- 872(1) Magnetization will have evident effect on4 Zhang Chunsun (章春笋)，Fan Shanshi (樊栓獅)，Guothe induction time of NGH.Yankun (鄭彦坤)，Zhen Xin (郑新)。Effects of VariousSurfactants on Natural Gas Hydrate Formation. Natural Gas(2) Under the experimental conditions, theIndustry (天然气工业)，2003, 23 (1): 91- -95induction time decrease from 99 min (average) in5 Zhong Y, Rogers R E Surfactant Effects on Gas Hydratewhich there is no magnetization to 47 minFormation. Chem. Eng. Sci, 2000, 55: 4175-4187(average) after magnetization of diluted solution6 Liu Yonghong (刘永红) , Guo Kaihua (郭开华), Liang Deqing(梁德青)，Fan Shuanshi (樊栓狮). The Effect of Ultrasonie(200 mg●kg-'， SDS) with magnetic fieldon the Growth Process of HCFC-141b Hydrate. Jourmnal ofintensity of 0.33 T. On the other hand, theWHUT (武汉理工大学学报)，2002, 24 (12): 21-23induction time of NGH prolonged to 189 min, 4317 Liu Yong (刘勇), Guo Kaihua (郭开华)，Liang Deqing (梁德青)，Fan Shuanshi (樊栓狮). Growth of Refrigerant Hydratemin, 221 min，and 107 min separately afterHCFC-141b Under Magnetic Field. China Science (中 国科学magnetization with magnetic field intensity of 0. 05B辑)，2003, 33 (1): 89- -96T, 0.11 T, 0.22 T, and 0.44 T.8 Xie Qifen (谢绮芬). Magnetization of Water (磁化水).Bejing Beijing Science and Technology Press, 1983(3) The evident effect of magnetization on the9 Mao Jufan (毛钜凡) , Liu Manqiong (刘曼琼)，Wang Henggrowth period of NGH has not been found at the(王恒)，trans. Magneization of Water (磁化水)。Chinaexperimental conditions.Measure Press, 198210 Miroslav Colic, Dwain Morse. The elusive mechanism of theReferencesmagnetic‘ memory’of water. Colloids and Surfaces A:Physicochemical and Engineering Aspects， 1999， 154;Sun Zhigao (孙志高), Fan Shuanshi (樊栓狮), Guo Kaihua167- -174(郭开华)。An Advance in the Research on Natural Gas11 Kashchiev D, Verdoes D, van Rosmalen G M J. CrystalHydrate. Natural Gas Industry (天然气工业)，2001，21Grorh，1991, 110; 373(1): 93- -9612 Kashchiev D. Nucleation; Basic Theory with Applications.2 Zhou Huaiyang (周怀阳)，Peng Xiaotong (彭晓彤), Ye YingOxford; Butterworth Heinemann, 2000(叶瑛). Natural Gas Hydrate (天然气水合物)。Beijing:China Ocean Press, 2000中国煤化工MYHCNMHG