Chasselin, H

Couvrat, M

Djokic, Marko

Marin, Guy

Olahová, Natália

Reyniers, Marie-Françoise

Riallant, F

Sarris, Stamatis

Van Geem, Kevin

English

Ghent University Academic Bibliography

aLaboratory for Chemical Technology, Ghent University http://www.lct.UGent.be Al-based coating for coke reduction during ethane steam cracking  Sarris S.A.a, Olahova N.a, Dokic M.a, Couvrat M.b, Riallant F.b, Chasselin H.b, Reyniers M.F.a, Marin G.B. a, Van Geem K.M.a 1 2016 AIChE Annual Meeting, San Francisco, U.S.A bManoir Industries, 12 Rue des Ardennes BP8401 - Pitres 27108 VAL DE REUIL Cedex  Outline • Introduction  • Experimental procedures  • Effluent analysis  • Coking rates   • SEM & EDX and XPS  • Conclusions  • Acknowledgments 2 2016 AIChE Annual Meeting, San Francisco, U.S.A 3 Steam Cracking 2016 AIChE Annual Meeting, San Francisco, U.S.A                                                     Main source of ethylene, propylene and other valuable hydrocarbons (i.e. olefins and aromatics)   commercially prevailing petrochemical process  Cracker C2H4, C3H6 POLYMERIZATION    UNITS Valuable Products  4 The enemy 2016 AIChE Annual Meeting, San Francisco, U.S.A                                                     Steam cracking is a very complex process:  High Temperatures  < 1300 ˚C for the metal   Feedstock composition  gases to heavy crude oils  Operating conditions  steam dilution, pressure, temperature  Reactor configuration  heat flux and mixing                                            Coke formation     5 Coke formation and Anti-coking 2016 AIChE Annual Meeting, San Francisco, U.S.A                                                     Main mechanisms lead to coke formation: Catalytic (initial catalytic behavior) Radical (long-term performance) Condensation (especially in heavy feeds)  Anti-coking technologies: 3D reactor technologies Feed additives Surface technologies 6 JSR set-up 2016 AIChE Annual Meeting, San Francisco, U.S.A Suitable for experimental validation of the effect of material, process conditions and pretreatments on coke formation  Well mixed reactor  Temperature measurement very close to the coupon  No reaction before the reactor  Mass track - accuracy of a μg/s  Different feedstock, different conditions 0.02.04.06.08.010.012.014.016.018.020.0051015202530350 1 2 3 4 5 6Coking rate [10-3g/s/m²]Weight increase [mg]Time [h]Filtered WeightFitted WeightCoking rateOn-line measurement of coking rates 7 2016 AIChE Annual Meeting, San Francisco, U.S.A  Initial coking rate is representative of the catalytic coking behavior of an alloy  Asymptotic coking rate refers to the long-term behavior of a material   Initial coking rate = Average coking rate value from 15 min - 1 h of cracking   Asymptotic coking rate  = Average coking rate value from 5 h - 6 h 8 CoatAlloyTM 2016 AIChE Annual Meeting, San Francisco, U.S.A Alumina forming layer  Providing an aluminum reservoir  Preventing inter diffusion  Chemically inert towards the base metal Studied conditions 9 2016 AIChE Annual Meeting, San Francisco, U.S.A Material effect CoatAlloy or MXM (as reference) DMDS effect Continuous addition (CA) of 41 ppmw S/HC and/or Presulfiding (PreS) with 500 ppmw DMDS/H2O Pretreatment effect N2 and H2O effect during stabilization and decoking Aging effect Cyclic (8 cc) Ethane Steam Cracking Experimental sequence 2016 AIChE Annual Meeting, San Francisco, U.S.A 10  Absence of Nitrogen during stabilization points  Only Steam/Air treatment is applied for CoatAlloy  1023 K    Air    12-14 h 1023 K  1173 K  N2 + Air or H2O/  Air   30 min 1173 K   H2O/  Air     15 min Pretreatment Decoking Only before the 1cc 4-7 cc Decoking 1173 K   H2O/  Air     15 min 3 cc of 6 h and decoking 4 cc of 1 h and decoking 1173 K     C2H6 + H2O   6 h 1023 K  1173 K  N2/Air or H2O/  Air   30 min 1173 K    H2O/  Air     15 min 1173 K     C2H6 + H2O   1 h 1-3 cc 1023 K  1173 K  N2 /Air or H2O/  Air   30 min 1173 K     C2H6 + H2O   6 h 8 cc Decoking 1173 K   H2O/  Air     15 min 1023 K  1173 K  N2 /Air or H2O/  Air   30 min Cooling down Last cc  Alloy reference CoatAlloy reference CoatAlloyPretreatmentFe-Ni-Cr optimalImproved only steamFe-Ni-Cr optimalImproved only steamidCracking Temperature (K)N2 during stabilizationdilutionCA DMDS (ppmw S per HC)PreS (ppmw DMDS per H2O)componentH2 4.25 4.23 4.26 4.24CO2 0.003 0.003 0.002 0.003CO 0.01 0.01 0.01 0.01CH4 7.05 7.14 7.08 7.17C2H6     30.21 29.96 30.02 29.88C2H4     49.76 50.42 49.87 50.41C3H8     0.11 0.12 0.11 0.12C3H6     0.76 0.77 0.76 0.77C2H2     1.38 1.41 1.39 1.421,3-C4H6   2.03 2.07 2.03 1.97Benzene 2.55 2.47 2.54 2.4841 410 500no no0.33 0.33CA CA+PreS1173 1173Effluent analysis 2016 AIChE Annual Meeting, San Francisco, U.S.A 11  No differences are observed in C oxides between coating and reference  No effect of the mat rial in the product distribution CA effect – Initial Rate 2016 AIChE Annual Meeting, San Francisco, U.S.A 12 CoatAlloy supresses catalytic coking in comparison with the reference  70 % ethane conversion  Tgas= 1173 K  41 ppmw S/HC of DMDS CA effect – Asymptotic Rate 2016 AIChE Annual Meeting, San Francisco, U.S.A 13  70 % ethane conversion  Tgas= 1173 K  41 ppmw S/HC of DMDS  CoatAlloy performs a factor 2 better than the reference after cyclic aging  CA + PreS effect – Initial Rate 2016 AIChE Annual Meeting, San Francisco, U.S.A 14  70 % ethane conversion  Tgas= 1173 K  41 ppmw S/HC of DMDS  500 ppmw DMDS/H2O  PreS has a less pronounced effect on the reference when is combined with CA  the two materials coke similarly CA + PreS effect – Asymptotic Rate 2016 AIChE Annual Meeting, San Francisco, U.S.A 15  70 % ethane conversion  Tgas= 1173 K  41 ppmw S/HC of DMDS  500 ppmw DMDS/H2O  CoatAlloy and MXM perform similarly after cyclic aging 16 SEM & EDX cross sectional analysis 2016 AIChE Annual Meeting, San Francisco, U.S.A  Increased uniformity of the coating is observed after application of steam  The absence of nitrogen during stabilization points is beneficial 17 XPS analysis pre-nitrated sample 2016 AIChE Annual Meeting, San Francisco, U.S.A  No nitrogen is identified on the surface of CoatAlloy after exposure to nitrogen  No nitrates are expected to be formed 18 Conclusions 2016 AIChE Annual Meeting, San Francisco, U.S.A Figure 4-10: Cross-sectional elemental mapping of coupon T3. The images were taken at a magnification of 3000x and a voltage of 15 kV.  CoatAlloy performs better than the reference under industrially relevant conditions  The coating stability, thickness and homogeneity is not affected throughout the cyclic aging experiments  Addition of steam during the in-situ decoking and pretreatment of the coating improves its subsequent coking behavior  Presulfiding shows no beneficial impact on the coking behavior of CoatAlloy  The presence of pure N2 has a negative effect on the homogeneity of the coating  The optimization of the pretreatment depending on the material composition and properties is of great interest        19 Acknowledgments 2016 AIChE Annual Meeting, San Francisco, U.S.A Figure 4-10: Cross-sectional elemental mapping of coupon T3. The images were taken at a magnification of 3000x and a voltage of 15 kV. • The research leading to these results has received funding from the Long Term Structural Methusalem Funding by the Flemish Government. • The Laboratory for Chemical Technology Questions 20 2016 AIChE Annual Meeting, San Francisco, U.S.A 

Al-based coating for coke reduction during ethane steam cracking

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Al-based coating for coke reduction during ethane steam cracking

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