Issue
Korean Journal of Chemical Engineering,
Vol.35, No.2, 337-347, 2018
Intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by redistribution of hydrogen between the units
The dehydrogenation and dewaxing of hydrocarbons of middle-distillate fractions, which proceed in the hydrogen medium, are of great importance in the petrochemical and oil refining industries. They increase oil refining depth and allow producing gasoline, kerosene, and diesel fractions used in the production of hydrocarbon fuels, polymer materials, synthetic detergents, rubbers, etc. Herewith, in the process of dehydrogenation of hydrocarbons of middle distillate fractions (C9-C14) hydrogen is formed in the reactions between hydrocarbons, and the excess of hydrogen slows the target reaction of olefin formation and causes the shift of thermodynamic equilibrium to the initial substances. Meanwhile, in the process of hydrodewaxing of hydrocarbons of middle distillate fractions (C5-C27), conversely, hydrogen is a required reagent in the target reaction of hydrocracking of long-chain paraffins, which ensures required feedstock conversion for production of low-freezing diesel fuels. Therefore, in this study we suggest the approach of intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by means of redistribution of hydrogen between the two units on the base of the influence of hydrogen on the hydrocarbon transformations using mathematical models. In this study we found that with increasing the temperature from 470 °C to 490 °C and decreasing the hydrogen/feedstock molar ratio in the range of 8.5/1.0 to 6.0/1.0 in the dehydrogenation reactor, the production of olefins increased by 1.45-1.55%wt, which makes it possible to reduce hydrogen consumption by 25,000Nm3/h. Involvement of this additionally available hydrogen in the amount from 10,000 to 50,000Nm3/h in the dewaxing reactor allows increasing the depth of hydrocracking of long-chain paraffins of middle distillate fractions, and, consequently improving low-temperature properties of produced diesel fraction. In such a way cloud temperature and freezing temperature of produced diesel fraction decrease by 1-4 °C and 10-25 °C (at the temperature of 300 °C and 340 °C respectively). However, when the molar ratio hydrogen/hydrocarbons decreases from 8.5/1.0 to 6.0/ 1.0 the yield of side products in the dehydrogenation reactor increases: the yield of diolefins increases by 0.1-0.15%wt, the yield of coke increases by 0.07-0.18%wt depending on the feedstock composition, which is due to decrease in the content of hydrogen, which hydrogenates intermediate products of condensation (the coke of amorphous structure). This effect can be compensated by additional water supply in the dehydrogenation reactor, which oxidizes the intermediate products of condensation, preventing catalyst deactivation by coke. The calculations with the use of the model showed that at the supply of water by increasing portions simultaneously with temperature rise, the content of coke on the catalyst by the end of the production cycle comprises 1.25-1.56%wt depending on the feedstock composition, which is by 0.3-0.6%wt lower that in the regime without water supply.
[References]
  1. Speight JG, The Refinery of the Future, Elsevier (2011).
  2. Stratiev D, Petkov K, Hydrocarb. Process., 88(9), 93, 2009
  3. Phillips G, Liu F, Hydrocarbon Eng., 8(9), 63, 2003
  4. Rana MS, Samano V, Ancheyta J, Diaz JAI, Fuel, 86(9), 1216, 2007
  5. Leprince P, Petroleum refining. Volume 3. Conversion Processes, Editions Technip (2000).
  6. Jones DSJ, Pujado PR, Handbook of Petroleum Processing, Springer (2006).
  7. Riazi MR, Characterization and Properties of Petroleum Fractions, ASTM manual series (2005).
  8. Ancheyta J, Alvarez-Majmutov A, Leyva C, John Wiley & Sons, Inc, New Jersey, Canada (2016).
  9. Sharafutdinov I, Stratiev D, Shishkova I, Dinkov R, Batchvarov A, Petkov P, Rudnev N, Fuel, 96(1), 556, 2012
  10. Lown AL, Peereboom L, Mueller SA, Anderson JE, Miller DJ, Lira CT, Fuel, 117, 544, 2014
  11. Anwar A, Garforth A, Fuel, 173, 189, 2016
  12. Lysenko SV, Kulikov AB, Onishchenko MI, Rakhmanov EV, Karakhanov EA, Moscow Univ. Chem. Bull., 71(1), 37, 2016
  13. Bao TT, Zhou B, Deng J, Wu ZJ, J. Shanghai Jiaotong University, 19(6), 721, 2014
  14. Speight JG, CRC Press (2016).
  15. Castaneda LC, Munoz AD, Ancheyta J, Catal. Today, 248, 220, 2014
  16. Long R, Picioccio K, Zagoria A, Petroleum Technology Quarterly, 16(3), 2011
  17. Cruz FE, De Oliveira S, Int. J. Thermodyn., 11(4), 187, 2008
  18. Docekal J, Int. J. Hydrog. Energy, 11(11), 709, 1986
  19. Castaneda LC, Munoz JAD, Ancheyta J, Fuel, 90(12), 3593, 2011
  20. Jie X, Gonzalez-Cortes S, Xiao T, Wang J, Yao B, SlocombeSlocombe DR, Al-Megren HA, Dilworth JR, Thomas JM, Edwards PP, Angew. Chem.-Int. Edit., 56(34), 10170, 2017
  21. Wu L, Liang XQ, Kang LX, Liu YZ, Chin. J. Chem. Eng., 25(8), 1061, 2017
  22. Sadighi S, Ahmad A, Rashidzadeh M, Korean J. Chem. Eng., 27(4), 1099, 2010
  23. Zahedi G, Yaqubi H, Ba-Shammakh M, Appl. Catal. A: Gen., 358(1), 1, 2009
  24. Hayati R, Abghari SZ, Sadighi S, Bayat M, Korean J. Chem. Eng., 32(4), 629, 2015
  25. Verstraete JJ, Le Lannic K, Guibard I, Chem. Eng. Sci., 62(18-20), 5402, 2007
  26. Alvarez A, Ancheyta J, Appl. Catal. A: Gen., 351(2), 148, 2008
  27. Sunggyu L, Encyclopedia of Chemical Processing, CRC Press (2005).
  28. Olah GA, Hydrocarbon Chemistry, Wiley, New York (2002).
  29. He SB, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (2009).
  30. Sanfilippo D, Miracca I, Catal. Today, 111(1-2), 133, 2006
  31. Paris RS, L'Abbate ME, Liotta LF, Montes V, Barrientos J, Regali F, Aho A, Boutonnet M, Jaras S, Catal. Today, 275, 141, 2016
  32. Rakoczy RA, Morse PM, Hydrocarb. Process., 92(7), 2013
  33. Frantsina E, Belinskaya N, Popova N, MATEC Web of Conferences, 85, 01023, 2016
  34. Frantsina EV, Ivashkina EN, Ivanchina ED, Romanovskii RV, Chem. Eng. J., 238, 224, 2015
  35. Belinskaya NS, Frantsina EV, Ivanchina ED, Chem. Eng. J., 329, 283, 2017
  36. Catal. Surv. Jpn., Ivashkina EN, Frantsina EV, Romanovsky RV, Dolganov IM, Ivanchina ED, Kravtsov AV, Catalysis in Industry, 4(2), 110 (2012).
  37. Kravtsov AV, Ivanchina ED, Ivashkina EN, Frantsina EV, Kiseleva SV, Romanovskii RV, Pet. Chem., 53(4), 267, 2013
  38. Belinskaya NS, Frantsina EV, Ivanchina ED, Popova NV, Belozertseva NE, Pet. Coal, 58(7), 695, 2016
  39. Chang N, Gu Z, Korean J. Chem. Eng., 31(5), 780, 2014
  40. Yoon S, Choi WC, Park YK, Kim HY, Lee CW, Korean J. Chem. Eng., 27(1), 62, 2010