Simulation of SiO2/S coating deposition in a pilot plant set-up for coking inhibition

Wang, Zhiyuan; Xu, Hong; Zhou, Jianxin; Luan, Xinjun

doi:10.1016/j.cherd.2012.07.006

Cited by 10 publications

(12 citation statements)

References 26 publications

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“…The validation and limitation of the surface reaction schemes and kinetic parameters have been discussed in our previous study, and the models used in Table 2 were in good agreement with the pilot scale test (Wang et al, 2013) . In Table 2, E a for Si deposition is chosen based on the apparent activation energy of the SiO 2 growth rate in a hot-wall TEOS system, and in S deposition they are based on the apparent activation energies for related sulfide pyrolyses (Wang et al, 2013). Therefore, the schemes present the apparent reactions correlating gas intermediates and coating deposition rates.…”

Section: Surface Reaction Modelsupporting

confidence: 58%

“…Therefore, a simplified one-step reaction mechanism is adopted according to our previous study (Wang et al, 2013). In this mechanism, Si(OH) 4 , H 2 S, CH 3 SH and CH 3 SCH 3 are proposed to be the final Si/S-containing intermediate products of the decomposition of TEOS and DMDS before entering the tube reactor according to the thermodynamic calculation (Wang et al, 2013). The surface reaction schemes and kinetic parameters are shown in Table 2.…”

Section: Surface Reaction Modelmentioning

confidence: 99%

“…For the species inside the reactor, the kinetic theory is used to compute the viscosity, heat capacity and (Wang et al, 2013). thermal conductivity of these species in the mixture (Wang et al, 2013;Reid et al, 1977;ANSYS, Inc., 2011;Hu et al, 2011). For the molecular transport, the kinetic theory is used to compute the binary mass diffusion coefficient for species i in species j.…”

Section: Physical Propertiesmentioning

confidence: 99%

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PREPARATION AND SIMULATION OF THE ON-LINE SiO2/S COATING FOR COKING INHIBITION IN THE INDUSTRIAL CRACKING FURNACE

Wang

Ding

Huo

2019

Braz. J. Chem. Eng.

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Coke formation inside radiant coils is one of the main problems during thermal cracking of hydrocarbons. The on-line preparation of the coating for coking inhibition is a promising technology because it provides more flexibility to the operators on site. The SiO 2 /S coating was prepared on the inner surface of coils in an 8-year-served GK-VI industrial cracking furnace. The effects of the coating preparation process on the operation of TLE were studied. The coking rates of the tube with and without coating preparation were evaluated by the trend change of tube metal temperature. Simulations of the coating deposition process were further carried out using the computational fluid dynamics approach. The results showed that a significant temperature increase at the outlets of TLEs during coating preparation were due to the accumulation of SiO 2 and S in a loose form under the TLE operating conditions when the concentration of coating precursors was 7500 ppm (wt. %). In the three tests, coating precursors were mainly completely consumed in tubes and TLEs. For the coated tube, the run time was extended by 4-7 days because the catalytic coking was decreased. No significant changes in the distribution of products and molar yields of main products were observed. In the simulations, it was found that increasing the inlet flow rate led to a more uniform thickness and improved the mass content of sulfur in the coating. In the tube bend section, circumferential nonuniformities for the deposition were due to circumferential differences in the temperatures and mass fractions. The mass fraction of S in the coating was within the range of 0.02%-0.1%. The control step for the SiO 2 /S coating deposition was kinetic. Based on the simulation results, the optimized coating preparation parameters were determined, i.e., the inlet flow rate of 15t/h, the outlet temperature of 1093K and the inlet mass concentration of 3000 ppm (wt. %).

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Section: Surface Reaction Modelsupporting

confidence: 58%

Section: Surface Reaction Modelmentioning

confidence: 99%

Section: Physical Propertiesmentioning

confidence: 99%

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PREPARATION AND SIMULATION OF THE ON-LINE SiO2/S COATING FOR COKING INHIBITION IN THE INDUSTRIAL CRACKING FURNACE

Wang

Ding

Huo

2019

Braz. J. Chem. Eng.

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“…Their results indicated that the anti-coking performance increased from 37% to 69% as the thickness of alumina coatings increased from 318 to 1280 nm. In addition, Xu et al [10][11][12] published a series of articles on the anti-coking property of the SiO 2 /S composite coating during light naphtha steam cracking and reported that the SiO 2 /S coating reduces coke yield by 60% compared with the uncoated tube. More recently, Liu et al [13] prepared a MnCr 2 O 4 spinel coating on HP40 alloy by pack cementation and subsequent thermal oxidation and applied it to inhibit coke formation during light naphtha thermal cracking.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Growth Characteristics and Properties of CVD TiN and TiO2 Anti-Coking Coatings

et al. 2019

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Coating metals with anti-coking materials inhibit their catalytic coking and are especially beneficial in the pyrolysis of hydrocarbon fuels. It is believed that growth characteristics and properties may play a pivotal role in the anti-coking performance of chemical vapor deposition (CVD) coatings. In this study, TiN and TiO 2 coatings were obtained by CVD using TiCl 4 -N 2 -H 2 and TiCl 4 -H 2 -CO 2 systems, respectively. The effects of deposition time, residence time, and partial pressure were examined, and the coating microstructure was characterized by scanning electron microscopy (SEM). The results reveal that the effect of deposition parameters on the growth characteristics of TiN and TiO 2 coatings is very different. The growth of the TiN coating shows characteristics of the island growth model, while the TiO 2 coating follows the layer model. In general, the growth rate of the star-shaped TiN crystals is higher than that of crystals of other shapes. For the TiO 2 coating, the layer mode growth characteristics indicate that the morphology of the TiO 2 coating does not change significantly with the experimental conditions. Coking tests showed that the morphology of non-catalytic cokes is not only affected by the temperature, pressure, and coking precursor, but is also closely related to the surface state of the coatings. Both TiN and TiO 2 coatings can effectively prevent catalytic coking and eliminate filamentous cokes. In some cases, however, the N or O atoms in the TiN and TiO 2 coatings may affect common carbon deposits formed by non-catalytic coking, such as formation of needle-like and flaky carbon deposits.

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“…For Al 2 O 3 coating, Eser et al [1] and Liu et al [15] investigated the effectiveness of MOCVD Al 2 O 3 coatings in mitigating carbon deposition due to thermal oxidation in thermal stressing of Jet A (350 o C and 3.5 MPa, 1 mL/min for 5 h), and thermal cracking of Chinese RP-3 jet fuel under supercritical conditions (inlet temperature, 575 o C; outlet temperature, 650 o C; pressure, 5 MPa), respectively. For SiO 2 coating, Xu et al [16][17][18] published a series of articles on anti-coking property of the SiO 2 /S composite coating during light naphtha steam cracking, and reported that the SiO 2 /S coating reduces coke yield by 60% compared with that observed in the blank tube. However, the MOCVD Al 2 O 3 coating is essentially amorphous instead of crystalline, and its surface presents coordinatively unsaturated Lewis acid sites and strong Brønsted acid sites, which are beneficial to form coking.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the anti-coking performance of CVD TiN, TiO 2 and TiC coatings for hydrocarbon fuel pyrolysis

Tang

Shi

Wang

et al. 2017

Ceramics International

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Simulation of SiO2/S coating deposition in a pilot plant set-up for coking inhibition

Cited by 10 publications

References 26 publications

PREPARATION AND SIMULATION OF THE ON-LINE SiO2/S COATING FOR COKING INHIBITION IN THE INDUSTRIAL CRACKING FURNACE

PREPARATION AND SIMULATION OF THE ON-LINE SiO2/S COATING FOR COKING INHIBITION IN THE INDUSTRIAL CRACKING FURNACE

Comparison of Growth Characteristics and Properties of CVD TiN and TiO2 Anti-Coking Coatings

Comparison of the anti-coking performance of CVD TiN, TiO 2 and TiC coatings for hydrocarbon fuel pyrolysis

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