بررسی اثر فشار بر میزان ماندگی گاز در راکتورهای حبابی و دوغابی

نوع مقاله: مقاله پژوهشی

نویسندگان

واحد تبدیلات گازی، پژوهشکده گاز، پژوهشگاه صنعت نفت

چکیده

در صنعت، معمولاً ستون راکتورهای حبابی و دوغابی در فشارهای بالای اتمسفری در حدود Bar ا7-35 کار می‌کنند. با وجود بررسی‌های زیادی که در مورد ستون‌های حبابی و دوغابی انجام شده، تعداد مطالعات آزمایشگاهی صورت گرفته در فشار بالا بسیار محدود می‌باشد. در این مقاله، اثر فشار و غلظت جامد بر روی ماندگی کلی گاز با استفاده از آزمایش اختلاف فشار بررسی شده است. آزمایش‌های انجام شده در این مطالعه با استفاده از گازهای نیتروژن و هوا، سیال پارافین و سیلیس به عنوان جامد در یک ستون راکتوری به قطر cm 16 و ارتفاع m 8/2 انجام گرفته است. محدوده فشار مطالعه شده در این تحقیق بین Bar ا7-18 است. مشاهده شد که افزایش فشار عملیاتی، موجب افزایش ماندگی کلی افزوده می‌شود. همچنین شدت اثر افزایش فشار بر روی ماندگی کلی گاز با افزایش غلظت جامد کاهش می‌یابد. در نهایت، معادله‌ای جهت برآورد ماندگی کلی گاز برای فشارهای بالا بر حسب چگالی گاز (ρg)، سرعت ظاهری گاز (Ug)، چگالی دوغاب (ρSL)، ویسکوزیته دوغاب (μSL) و کشش سطحی مایع (σL) ارائه شد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating the Effect of Pressure on Gas Holdup of Bubble and Slurry Bubble Columns

نویسندگان [English]

  • Mohammadreza Alaei
  • Mohammad Irani
  • Ali Nakhaeipour
Gas Research Division, Research Institute of Petroleum Industries
چکیده [English]

Bubble and slurry bubble column reactors usually work under pressures beyond the atmosphere in the industries. Although many studies have been done about bubble and slurry bubble column reactors, experimental studies under elevated pressure are very limited. In this study, the effects of pressure and slurry concentration on the gas holdup have been investigated by using pressure difference tests. The experiments of this study are made under pressures up to 18 bar and paraffin and silica are used as the liquid and solid contents. Increasing the operation pressure leads to an increase in gas holdup. It is also found out that the effect of pressure is vanished by increasing the slurry concentration. The experiments are performed in a column with a diameter of 16 cm and a height of 2.8 m. The gases used are nitrogen and air. Finally, a new experimental correlation is developed as a function of gas density (ρg), superficial velocity of gas (Ug), slurry density (ρSL), slurry viscosity (μSL), and liquid surface tension (σL); the correlation is obtained by using the data extracted from this investigation and is in good agreement with the experimental data.

کلیدواژه‌ها [English]

  • Bubble Column Reactor
  • Slurry Bubble Column Reactor
  • Gas Holdup
  • Elevated Pressure
  • Experimental Correlation
مراجع

[1]. Krishna R., and Sie S. T., “Design and scale up of a bubble column slurry reactor for Fischer-Tropsch synthesis. Chemical Engineering Science”, 56(2): pp. 537-545, 2001.

[2]. Fan L.S., Yang G.Q., Lee D.J., Tsuchiya K. and Luo X., “Some aspects of high-pressure phenomena of bubbles in liquids and liquid-solid suspensions”, Chemical Engineering Science, 54(21): pp. 4681-4709, 1999.

[3]. Kemoun A., Kemoun A., Ong B. Ch., Gupta P., Al-Dahhan M. H. and Dudukovic M. P., “Gas holdup in bubble columns at elevated pressure via computed tomography. International Journal of Multiphase Flow”, 27(5): pp. 929-946, 2001.

[4]. Kojima H., Sawai J., and Suzuki H., “Effect of pressure on volumetric mass transfer coefficient and gas holdup in bubble column”, Chemical Engineering Science, 52(21-22): pp. 4111-4116, 1997.

[5]. Krishna R., Urseanu M.I., and Dreher A.J., “Gas hold-up in bubble columns: influence of alcohol addition versus operation at elevated pressures”, Chemical Engineering and Processing, 39(4): pp. 371-378, 2000.

6]. Letzel H. M., Schouten J. C., Krishna R. and van den Bleek C. M., “Gas holdup and mass transfer in bubble column reactors operated at elevated pressure” Chemical Engineering Science, 54(13-14): pp. 2237-2246, 1999.

[7]. Letzel H.M., Schouten J.C., van den Bleek C.M. and Krishna R., “Influence of elevated pressure on the stability of bubbly flows”, Chemical Engineering Science, 52(21-22): pp. 3733-3739, 1997.

[8]. Letzel M.H., Schouten J.C., van den Bleek C.M. and Krishna R. , “Effect of gas density on large-bubble holdup in bubble column reactors”, AIChE Journal, 44(10): pp. 2333-2336, 1998.

[9]. Lin T.J., Tsuchiya K., and Fan L.S., “Bubble flow characteristics in bubble columns at elevated pressure and temperature”, AIChE Journal, 44(3): pp. 545-560, 1998.

[10]. Luo X., Lee D. J., Lau R.,Yang G. and Fan L.S., “Maximum stable bubble size and gas holdup in high-pressure slurry bubble columns”, AIChE Journal, 45(4): pp. 665-680, 1999.

[11]. Reilly I.G., Scott D. S., Debruijn T. J. W and Macintyre D., “The role of gas phase momentum in determining gas holdup and hydrodynamic flow regimes in bubble column operations”, The Canadian Journal of Chemical Engineering, 72(1): pp. 3-12, 1994.

[12]. Shollenberger K.A., Torczynski J.R., Adkins D.R., O›Hern T.J. and N.B. Jackson, “Gamma-densitometry tomography of gas holdup spatial distribution in industrial-scale bubble columns”, Chemical Engineering Science, 52(13): pp. 2037-2048, 1997.

[13]. Wilkinson P.M., Spek A.P., and van Dierendonck L.L. , “Design parameters estimation for scale-up of high-pressure bubble columns”, AIChE Journal, 38(4): pp. 544-554, 1992.

[14]. Kumar S., Dudukovic M.P., and Toseland B.A., Measurement techniques for local and global fluid dynamic quantities in two and three phase systems, in Other Information: PBD: p. Medium: ED; Size: pp. 52, Jan 1998.

[15]. Boyer C., Duquenne A.-M., and Wild G., “Measuring techniques in gas-liquid and gas-liquid-solid reactors”, Chemical Engineering Science, 57(16): pp. 3185-3215., 2002.

[16]. Su X. and Heindel T.J., “Gas Holdup in a Fiber Suspension”, The Canadian Journal of Chemical Engineering, 81(3-4): pp. 412-418, 2003.

[17]. Su, X. and Heindel T.J., “Gas Holdup Behavior in Nylon Fiber Suspensions. Industrial & Engineering Chemistry Research”, 43(9): pp. 2256-2263, 2004.

[18]. Kara S., Shah Y. T., and Carr N. L., “Hydrodynamics and axial mixing in a three-phase bubble column”, Industrial & Engineering Chemistry Process Design and Development, 21(4): pp. 584-594, 1982.

[19]. Tang C. and T.J. Heindel, “Time-dependent gas holdup variation in an air-water bubble column”, Chemical Engineering Science, 59(3): pp. 623-632, 2004.

[20]. Tang C. and T.J. Heindel, “Effect of fiber type on gas holdup in a cocurrent air-water-fiber bubble column”, Chemical Engineering Journal, 111(1): pp. 21-30, 2005.

[21]. Tang C. and Heindel T.J., “Gas-liquid-fiber flow in a cocurrent bubble column”, AIChE Journal, 51(10): pp. 2665-2674, 2005.

[22]. Behkish A., Men Z., Inga J. R. and Morsi B. I, “Mass transfer characteristics in a large-scale slurry bubble column reactor with organic liquid mixtures”, Chemical Engineering Science, 57(16): pp. 3307-3324, 2002.

[23]. Dewes I. and Schumpe A., “Gas density effect on mass transfer in the slurry bubble column”, Chemical Engineering Science, 52(21-22): pp. 4105-4109, 1997.

[24]. Idogawa K., Ikeda K., Fukuda T., and Morooka S., “Effect of gas and liquid properties on the behavior of bubbles in a column under pressure”, International Chemical Engineering, 27: p. 93-99, 1987.

[25]. Jiang P., Lin T. J., Luo X. and Fan L. S, “Flow visualization of high pressure (21 MPa) bubble column: bubble characteristics”, Chemical engineering research & design, 73: pp. 269-274, 1995.

[26]. Lau R., Peng W., Velazquez-Vargas L. G., Yang G. Q, and Fan L.-S., “Gas−Liquid Mass Transfer in High-Pressure Bubble Columns. Industrial & Engineering Chemistry Research”, 43(5): pp. 1302-1311, 2004.

[27]. Lemoine R., Behkish A. and Morsi B.I., “Hydrodynamic and Mass-Transfer Characteristics in Organic Liquid Mixtures in a Large-Scale Bubble Column Reactor for the Toluene Oxidation Process”, Industrial & Engineering Chemistry Research, 2004. 43(19): pp. 6195-6212.

[28]. Oyevaar M.H., De La R., Sluijs T., C.L. Van Der, and K.R. Westerterp, Interfacial areas and gas hold-ups in bubble columns and packed bubble columns at elevated pressures. Chemical Engineering and Processing: Process Intensification, 26(1): pp. 1-14, 1989.

[29]. Oyevaar M.H., Bos R., and K.R., “Interfacial areas and gas hold-ups in gas--liquid contactors at elevated pressures from 0.1 to 8.0 MPa”, Chemical Engineering Science, 46(5-6): pp. 1217-1231, 1991.

[30]. Pohorecki R., Pohorecki R., Moniuk W. and Zdrójkowski A., “Hydrodynamics of a pilot plant bubble column under elevated temperature and pressure”, Chemical Engineering Science, 56(3): pp. 1167-1174, 2001.

[31]. Stegeman D., Knop P. A., Wijnands A. J. G., and Westerterp K. R., “Interfacial Area and Gas Holdup in a Bubble Column Reactor at Elevated Pressures. Industrial & Engineering Chemistry Research”, 35(11): pp. 3842-3847, 1996.

[32]. Tarmy B., Min Chang, Coulaloglou C. and Ponzi P., “Hydrodynamic characteristics of three phase reactors”, Chemical Engineering, 407: pp. 18-23, 1984.

[33]. Urseanu M.I., Guit R.P.M, Stankiewicz A., Van Kranenburg G., and Lommen J.H.G.M., “Influence of operating pressure on the gas hold-up in bubble columns for high viscous media”, Chemical Engineering Science. 58(3-6): pp. 697-704.

[34]. Wilkinson P.M., Haringa H., and Van Dierendonck L.L., “Mass transfer and bubble size in a bubble column under pressure”, Chemical Engineering Science, 49(9): pp. 1417-1427.

[35]. Yang G.Q. and Fan L.S., “Axial liquid mixing in high-pressure bubble columns”, AIChE Journal, 49(8): pp. 1995-2008, 2003.

[36]. Behkish A., Lemoine R., Sehabiague L., Oukaci R. and Morsi B. I., “Gas holdup and bubble size behavior in a large-scale slurry bubble column reactor operating with an organic liquid under elevated pressures and temperatures”, Chemical Engineering Journal, 128(2-3): pp. 69-84, 2007.

[37]. Deckwer W., Louisi Y., Zaidi A. and Ralek M., “Hydrodynamic properties of Fischer-Tropsche slurry reactor”, Industrial & Engineering Chemistry Process Design and Development, 19: pp. 699-708, 1980.

[38]. Inga J.R. and Morsi B.I., “Effect of Operating Variables on the Gas Holdup in a Large-Scale Slurry Bubble Column Reactor Operating with an Organic Liquid Mixture”, Industrial & Engineering Chemistry Research, 1999. 38(3): p. 928-937.

[39]. Vafopulos I., K., and Moser F., “The influence of partial-and gas density on the mass transfer”, Chemical Engineering Technology, 47: pp. 681-786, 1975.

[40]. Krishna R., P.M. Wilkinson, and L.L. Van Dierendonck, “A model for gas holdup in bubble columns incorporating the influence of gas density on flow regime transitions”, Chemical Engineering Science, 46(10): pp. 2491-2496, 1991.

[41]. Krishna R., De Swart J. W. A., Hennephof D. E, Ellenberger J.and Hoefsloo H. C. J., “Influence of increased gas density on hydrodynamics of bubble-column reactors”, AIChE Journal, 40(1): pp. 112-119, 1994.

[42]. Krishna R., De Swart J. W. A., Ellenberger J., G. B. Martina and C., “Gas holdup in slurry bubble columns: Effect of column diameter and slurry concentrations”, AIChE Journal, 43(2): pp. 311-316, 1997.

[43]. Koide K., Takazawa A., Komura M.and Matsunaga H., “Gas holdup and volumetric liquid-phase mass transfer coefficient in solid-suspended bubble columns”, Journal of chemical engineering of Japan, 17(5): pp. 459-466, 1984.

[44]. Kelkar B.G., Y.T. Shah, and N.L. Carr, “Hydrodynamics and axial mixing in a three-phase bubble column”, Effects of slurry properties. Industrial & Engineering Chemistry Process Design and Development, 23(2): pp. 308-313, 1984.

[45. Yasunishi A., Fukuma M., and Muroyama K., “Measurement of Behavior of Gas Bubbles and Gas Holdup in a Slurry Bubble Column by a Dual Electroresistivity Probe Method”, Journal of Chemical Engineering of Japan, 19: pp. 444-449, 1986.

[46]. Hikita H., Asai S., Tanigawa K., Segawa K.and Kitao M., “Gas hold-up in bubble columns”, The Chemical Engineering Journal, 20(1): pp. 56-67, 1980.