Effect of Operating Conditions and Additives on the Product Yield and

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Effect of Operating Conditions and Additives on the Product Yield and Sulfur Content in Thermal Cracking of Vacuum Residue from Abadan Refinery Amir Safiri1, 2, Javad Ivakpour1*, Farhad Khorasheh2** 1

2

Petroleum Refining Division, Research Institute of Petroleum Industry, Tehran, Iran Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran

Abstract Thermal cracking of vacuum distillation residue of Abadan refinery in Iran was performed under delayed coking conditions to investigate the effect of operating conditions on the yield and sulfur content of products. At reactions temperatures of 440 to 500°C and pressures of 1, 3 and 5 bar, the products included gases, liquids, and coke. The yields of liquid products were higher at 1 bar compared with those for higher pressures. Increasing the reaction temperature at given reaction pressure led to an increase in the yield of liquid products. Increasing the reaction pressure at a given reaction temperature led to higher yields of coke and gases as well as a decrease in the sulfur content of coke and liquid products. The effects of iron oxide and aluminum oxide nanoparticle additives on the product yields and sulfur content were also investigated. The results indicated that different concentration of additives would increase the liquid yields and decrease the sulfur content of both coke and liquid products as compared with experiments with no nanoparticles added.

Keywords: Vacuum Distillation residue, Delayed Coking, Thermal Cracking, Petroleum Coke, Additives

*

[email protected], +982148255038, P. O. Box: 1485733111

**

[email protected], +982166165411, P. O. Box: 11155-9465 1 ACS Paragon Plus Environment

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1. Introduction Petroleum refining processes lead to production of heavy hydrocarbons known as residue that contain significant amounts of sulfur and metals that contribute to air pollution when they are burned. Among the various processes for residue upgrading, non-catalytic thermal processes are preferred by the refineries due to their simplicity, low cost, and mild operating conditions. The high metal and sulfur content of residues would contribute to catalyst deactivation for any catalytic residue upgrading processes. Thermal cracking processes are therefore more suitable for residues. Delayed coking is often used as a thermal cracking process for residue upgrading with the aim of converting the residues to lighter distillation products including fuel gas, naphtha, and light and heavy gas oil. Delayed coking is economically attractive and can be used to upgrade any feedstock containing different amounts of sulfur and metals. Coke is also formed as a major product in delayed coking. Raw petroleum coke can be used directly as fuel, as additive in the cement industry, combined with coal as fuel in utilities and cogeneration facilities, in synthesis gas production by gasification, and in higher grade quality for producing anode and graphite electrodes. 1-14 In thermal cracking of residue free radicals are primarily formed by breaking of carbon-carbon bonds. The resulting free radicals could either decompose to form a smaller olefin or stabilize by hydrogen abstraction to give the corresponding saturated compound. The lighter components formed by cracking of residue contribute to gas and liquid products while the heavier components are polymerized to form coke.

15

The thermal cracking reactions result in the

formation of a series of precursor molecules that are separated from the oil phase to form a new meso-phase when their concentration is increased with increasing residue conversion.

6, 16

Asphaltenes are known as the precursors for coke formation. 17 Feed properties and process conditions can affect the quantity and quality of delayed coking products. Feed properties such as density, aromatic and asphaltene content, Conradson carbon residue, and sulfur and metal content play an important role on the quality of products. After carbon and hydrogen, the most abundant element in crude oil is sulfur. Sulfur compounds are found in organic and inorganic forms in petroleum fractions. Inorganic sulfur such as elemental 2 ACS Paragon Plus Environment

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sulfur, hydrogen sulfide and iron sulfide could be present in the form of solution or suspension in crude oil. On the other hand, organic sulfur compounds such as thiols, sulfides, and thiophenic compounds are the main source of sulfur in crude oil. The sulfur compounds in residues mainly appear in poly-aromatic ring structures. Thiols, sulfides, aromatic sulfides and heavy disulfides that are present in naphthenic and aromatic structures of residue fractions have high reactivity and are likely converted to hydrogen sulfide at high temperatures. In the case of sulfur in aromatic ring structures, however, sulfur removal is only slightly achieved.

18, 19

In thermal

cracking of residue, the main parameters affecting the sulfur content of the products are the feed sulfur content and the reaction temperature. Higher sulfur content, density and Conradson carbon residue of feedstock would result in an increase in the sulfur content of products. Since most of the sulfur tend to concentrate in the heavy fractions of crude oils, heavier feedstock have higher sulfur content.

20

Moreover for a given feedstock, increasing the thermal cracking temperature

would usually result in a higher amount of sulfur in the liquid products as the enhanced cracking of the feedstock components would lead to the formation of sulfur containing cracked components in the liquid products. Furthermore, carbon-sulfur bond is a weak bond in the hydrocarbon molecules of the crude oil that is more readily cracked compared with other bonds. Thus by increasing the reaction temperature, the cleavage of carbon-sulfur bonds would result in an increase in the sulfur content of gas and liquid products. Many investigators have reported that with increasing thermal cracking temperature, the sulfur content of gas and liquid products had increased while the sulfur content of coke had decreased. 21-23 Product yields from thermal cracking of residue also depend on feedstock properties including Conradson carbon residue, asphaltene content and density. Coke yield was found to increase with increasing Conradson carbon residue content.

24

Additionally, the yield of liquid products

was found to increase with decreasing density of the feedstock.

25

Furthermore, low coking

temperatures lead to the formation of pitch or soft coke. When the coking temperature is too high, the coke that is produced is hard and difficult to be separated from the coke drum. High coking temperatures would also increase the possibility of coke formation in the furnace and pipelines.

26, 27

Many investigations have reported the effects of temperature on product yields

indicating an increase in the liquid and gas yields and a decrease in the coke yield with increasing reaction temperature.

24, 28

Singh et al. investigated the thermal cracking of four

different feedstock in an autoclave reactor at different temperatures and reported that an increase 3 ACS Paragon Plus Environment

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in the reaction temperature increased the yields of gas and liquid products for all feedstock.

7

Hauser et al. studied the thermal cracking of three different residues obtained from vacuum distillation of Kuwait crude oil and observed that with increasing reaction temperature, the yields of gaseous products increased slightly while the increase in the yields of liquid products and the decrease in the pitch yields were more significant.

21

Asgharzadeh et al. (2011) investigated the

thermal cracking of vacuum distillation residues from Tehran and Bandar Abbas refineries at different temperatures and reported that an increase in the reaction temperature led to an increase in the yields of gas and liquid products. 29 They found that for a given reaction temperature, the product yields first increased with increasing reaction time but subsequently reached constant levels at longer residence times. The same behavior for product yields with residence time was also observed for higher reaction temperatures except that the approach to constant yield levels was achieved at lower residence times. This observation was also reported by other investigators indicating that as the reaction temperature is increased, the time required for completion of the thermal cracking process is reduced due to the higher rates of cracking and polymerization reactions.

30

The effect of reaction pressure on the quantity and quality of thermal cracking

products has also been reported by some investigators indicating that an increase in reaction pressure would lead to increased yields of coke and gaseous products. 24, 27, 28 High yield of liquid products with low sulfur content is an important issue for any coking process. Numerous studies have investigated the effect of temperature on product yields but only limited data is available on the effect of pressure on the product yields and sulfur content. Furthermore, using additives such as iron and aluminum oxides could increase the products quality. The metal oxides are considered as useful additives in catalytic cracking processes due to their high surface area as well as high concentration and strength of acid sites.

31

Results of

previous studies reveal that aluminum oxide could increase both the catalyst stability at higher temperatures and the rate of cracking reactions by reducing the activation energy.

32, 33

It is also

shown that the rate of cracking reactions could be improved using iron oxide-modified ZSM-5 catalyst by enhancing the acidity and lowering the activation energy by up to 21 kJ/mol.

34

Bortnovsky showed that when added as additives, aluminum oxide causes more cracking in comparison with iron oxide molecules due to the presence of more Bronsted acid sites. 35

4 ACS Paragon Plus Environment

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In this work, the thermal cracking of vacuum distillation residue from Abadan refinery was carried out in an autoclave reactor under delayed coking conditions to investigate the effects of operating conditions including reaction temperature and pressure, as well as addition of iron oxide and aluminum oxide nanoparticles as additives, on the yields and sulfur contents of the products.

2. Experimental Section 2.1 Materials The properties of vacuum distillation residue from Abadan refinery that was used as the feedstock are presented in Table 1. The properties of iron oxide and aluminum oxide nanoparticles that were used as additives are presented in Table 2.

2.2 Experimental Procedure Figure 1 shows the schematic diagram of the experimental apparatus that was used for thermal cracking of the feedstock. In each experiment, 45 g of feed was placed in a 450 ml stainless steel autoclave. Nitrogen flow (1) was used to purge the reactor prior to the start of a run, to maintain the reactor pressure, and to remove the reaction products. Pressure gauge (3) indicated the nitrogen pressure after the regulator that was considered as the reactor working pressure. A needle valve (4) was used to adjust the nitrogen flow rate at levels low enough that foaming and blocking of the exit line was prevented. The nitrogen flow rate as indicated by the flow meter (5) was set to be 15 ml/min. A check valve (6) was used to prevent the back flow of thermal cracking products since the pressure inside the autoclave could increase significantly at the beginning of a run due to the rapid formation of gaseous products especially at high reaction temperatures. The autoclave (7) was located inside a furnace (8) that provided the required heating. The products removed from the autoclave by the nitrogen flow would enter the condenser (10) where those that would condense at ambient would be accumulated in the storage tank (9). The temperature of the gas leaving the condenser was determined by thermometer (11) 5 ACS Paragon Plus Environment

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and its flow rate was measured by a flow meter (12). A back pressure regulator (13) was used to maintain the autoclave pressure at the desired value. The gas stream was then vented after passing through a gas scrubber (14). In all experiments the heating rate was adjusted so that the desired reaction temperature was reached at a rate of 10oC/min and subsequently maintained for 3 hours. Coke and liquid products inside the autoclave were collected once the autoclave had cooled to room temperature. Once the furnace temperature had started to increase at the start of a thermal cracking experiment, volatile components were removed from the feedstock by the nitrogen flow. The liquid products were collected in the storage tank after passing through the condenser. During the initial stage of heating the gas flow rates indicated by flow meters (5) and (12) were identical as no thermal cracking reactions had occurred leading to the formation of non-condensable product gases. With increasing temperature and the onset of thermal cracking of the feedstock, the flow of non-condensable gases resulted in a higher gas flow rate indicated by flow meter (12) compared with flow meter (5). The increase in the product gas flow rate led to an increase in the number of gas bubbles discharged from the gas scrubber. The bubble count from the scrubber was used as an indicator to establish the minimum temperature for the onset of thermal cracking of the feedstock at this pressure. For a more accurate determination of this minimum temperature, the furnace temperature could be increased at a lower rate (for example 1oC/min as compared with 10oC/min employed in this study). To find the products yields, the weight of the empty autoclave was measured (by 2-digit balance) prior to the start of each experiment. Then, the weight of feed sample was determined considering the difference between the reactor containing the sample and initial empty one. Having determined the weight of the autoclave and the remaining solid product at the end of the experiment, the yield of produced coke could be calculated. The amount of liquid products was determined by measuring the weight of the storage tank before and after each experiment. The amount of produced gas can be calculated by mass balance between the feed and coke, liquid, and gaseous products.

3. Results and Discussion 3.1 Effect of Coking Parameters on Products Yield and Sulfur Content 6 ACS Paragon Plus Environment

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Table 3 indicates that the liquid product yields (wt. %) increased with increasing reaction temperatures. This was expected as higher temperatures lead to higher free radical concentrations that enhance thermal cracking reaction rates. Data presented in this table indicate that at the reaction pressure of 1 bar, coke yields decreased with increasing temperature and gas yields were only slightly affected by the increasing reaction temperature. Table 3 also illustrates that at a constant temperature, the yield of liquid products decreased with increasing reaction pressure. With increased reaction pressure, the vaporization of cracked products is reduced allowing the cracked products to participate in secondary reactions including radical addition and polymerization reactions leading to heavier components, as well as further cracking leading to the formation of lighter products. As indicated in this table, the increase in both coke and gas yields with increasing reaction pressure came at the expense of the yield of liquid products. Thus the process goal of a high yield of liquid products can best be achieved at low pressures and high temperatures. Visual inspection of the liquid products also indicated a more viscous and darker liquid product with increasing reaction temperature as enhanced cracking of the feedstock at higher temperatures led to more residue components being cracked and ending up in the liquid products. Furthermore, in all level of temperatures and pressure parameters, rate of production of liquid goes up fast at first, then with a slow rate reduced, until no liquid produced. Figure 2 shows a typical pattern for the rate of bubble discharge from the scrubber at 1 bar and 400oC as the reaction proceeds. For the first hour after the start of a run, the bubble discharge rate is almost constant. A sudden increase in the effluent gas stream is indicative of the onset of thermal cracking. The reactor is kept at the reaction temperature for 3.5 hours after the onset of thermal cracking. During this phase of constant reaction temperature, the effluent gas flow rate (rate of thermal cracking reactions) would gradually decrease to that representing the nitrogen flow as the residue inside the reactor would be converted to different reaction products. The rate of thermal cracking reactions is highest initially gradually declining until no further products are produced. For most of the experiments performed in this study, the reaction was completed after about 3 hours from the onset of the reaction. Table 3 also present the coke yields at different reaction temperatures and pressures. At a constant pressure, coke yield decreased with increasing temperature as heavier residue components are cracked to lighter products rather than converting to coke. In addition, by increasing the temperature volatile substances trapped in the coke structure were released. At a 7 ACS Paragon Plus Environment

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constant temperature, coke yield increased with increasing pressure due to enhanced polymerization reactions and reduced vaporization of cracked residue. The coke formed at higher temperatures was also very hard and its removal from the autoclave was quite difficult. As illustrated in Table 4, the sulfur content of the liquid products increased with increasing reaction temperature. Carbon-sulfur bonds are weaker than carbon-carbon bonds and crack more readily under thermal cracking conditions. As sulfur is concentrated in the asphaltenes and resins present in the residue and cracking of carbon-sulfur bonds of residue components would lead to sulfur species ending up in the liquid products thus increasing the sulfur content of the liquid products. At a constant reaction temperature, an increase in the reaction pressure led to a decrease in the sulfur content of the liquid products. This result was consistent with a decrease in liquid product yields with increasing pressure as more of the residue, including the sulfur species, ended up in coke. Consistent with the above trends for sulfur contents of the liquid products were the results obtained for the sulfur content of coke presented in Table 4 indicating that the weight percent of sulfur in coke decreased with increasing reaction temperature at a constant pressure and decreased with increasing pressure at a constant reaction temperature due to an increase in the cracking of residue and overall coke yield with increasing pressure.

3.2 Effect of additives on product yields and sulfur content Liquid products are the most valuable products in delayed coking where the main objective is to maximize the production of distillates from heavy residue. To investigate the effect of different nanoparticles on the product yield and sulfur content from thermal cracking of residue, two different nanoparticles at 3 concentration levels of 100, 500 and 1000 ppm, were added to the feedstock and thermal cracking reactions were carried out at the pressure of 1 bar and a reaction temperature of 480oC was named selected point. The yields and sulfur contents of products in the presence of additives at different concentration levels are reported in Table 5 indicating that for all cases, the addition of nanoparticles resulted in an increase in the yield of liquid products especially with aluminum oxide at 1000 ppm and iron oxide at 500 ppm in comparison with thermal cracking with no additives. Furthermore, the sulfur content of coke and liquid products decreased when additives were used compared with thermal cracking without any additives. 8 ACS Paragon Plus Environment

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When additives were used, the nanoparticles were distributed within the residue acting as catalyst to facilitate the cracking reactions leading to higher liquid product and lower coke yields. The enhanced cracking activity, possibly due to the presence of acid sites of the additives, also led to the removal of lighter sulfur compounds resulting in slightly lower sulfur content of both coke and liquid products. The exact catalytic role of the additives is the subject of our ongoing investigations. The metal contents of the coke as determined by ASTM D5056 test indicated that almost all of the iron and aluminum nanoparticles added to the feed had accumulated in the product coke. The concentration of nanoparticles should therefore be checked to be within the acceptable range of values for iron or aluminum in the raw coke. To estimate the error associated with the experimental system, the runs at 480oC and pressures of 1 and 3 bar were repeated and the results are presented in Table 6 indicating a reasonable agreement between two sets of data.

4. Conclusions Abadan vacuum distillation residue has been thermally cracked in a laboratory scale autoclave by delayed coking. The reaction products including gas, liquid, and coke were determined at different reaction temperature and pressures. The results indicated that higher reaction pressures led to an increase in the coke yields and a decrease in the liquid product yields. Increasing reaction temperature at a constant pressure led to an increase in the yield and the sulfur content of liquid products and a decrease in the yield and sulfur content of coke. At a constant reaction temperature, liquid yields and the sulfur content of liquid and coke decreased and while the yields of coke and gas products increased with increasing pressure. Addition of 100 to 1000 ppm of iron oxide or aluminum oxide nanoparticles led to an increase the yield of liquid products and a slight decrease in the sulfur content of both coke and liquid products.

Acknowledgements


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The authors are thankful to the Research Institute of Petroleum Industry of Iran (RIPI) and Iranian Mines and Mining Industries Development and Renovation Organization (IMIDRO) for financially supporting this work.

References 1.

Halim, H. P.; Im, J. S.; Lee, C. W., Preparation of needle coke from petroleum by-

products. Carbon letters, 2013, Vol. 14, No. 3, p: 152-161. 2.

Menoufy, M.; Ahmed, H.; Betiha, M.; Sayed, M., A Comparative study on hydrocracking

and hydrovisbreaking combination for heavy vacuum residue conversion. Fuel 2014, 119, 106110. 3.

Vafi, K.; McCaffrey, W. C.; Gray, M. R., Minimization of Coke in Thermal Cracking of

Athabasca Vacuum Residue in a High-Temperature Short-Residence Time Continuous Flow Aerosol Reactor. Energy & Fuels 2012, 26, (10), 6292-6299. 4.

Zachariah, A.; Wang, L.; Yang, S.; Prasad, V.; de Klerk, A., Suppression of coke

formation during bitumen pyrolysis. Energy & Fuels 2013, 27, (6), 3061-3070. 5.

Guo, A.; Zhang, X.; Wang, Z., Simulated delayed coking characteristics of petroleum

residues and fractions by thermogravimetry. Fuel Processing Technology 2008, 89, (7), 643-650. 6.

Ebrahimi, S.; Moghaddas, J.; Aghjeh, M., Study on thermal cracking behavior of

petroleum residue. Fuel 2008, 87, (8), 1623-1627. 7.

Singh, J.; Kumar, M.; Saxena, A. K.; Kumar, S., Studies on thermal cracking behavior of

residual feedstocks in a batch reactor. Chemical engineering science 2004, 59, (21), 4505-4515. 8.

Chen, Q.; Yin, Q.; Wang, S.; Hua, B., Energy-use analysis and improvement for delayed

coking units. Energy 2004, 29, (12), 2225-2237. 9.

Gary, J. H.; Handwerk, G. E., Petroleum Refining: Technology and Economics. 4 ed.;

Marcel Dekker: New York, 2001. 10.

Shen, H.; Ding, Z.; Li, R. Thermal Conversion–An Efficient Way for Heavy Residue

Processing, 15th World Petroleum Congress, 1997. 11.

Rahmani, S.; McCaffrey, W.; Gray, M. R., Kinetics of solvent interactions with

asphaltenes during coke formation. Energy & fuels 2002, 16, (1), 148-154.


Page 11 of 22

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

12.

Role of chain reactions and olefin formation in cracking, hydroconversion, and coking of

petroleum and bitumen fractions. Energy & fuels 2002, 16, (3), 756-766. 13.

Elliott, J.; Wedlak, D. In Residue upgrading with SYDEC delayed coking: Benefits and

economics, 1st Asia bottom of the barrel technology conference, 2007. 14.

Castañeda, L.; Muñoz, J.; Ancheyta, J., Combined process schemes for upgrading of

heavy petroleum. Fuel 2012, 100, 110-127. 15.

Alshareef, A. H.; Scherer, A.; Tan, X.; Azyat, K.; Stryker, J. M.; Tykwinski, R. R.; Gray,

M. R., Effect of chemical structure on the cracking and coking of archipelago model compounds representative of asphaltenes. Energy & Fuels 2012, 26, (3), 1828-1843. 16.

Gentzis, T.; Rahimi, P., A microscopic approach to determine the origin and mechanism

of coke formation in fractionation towers. Fuel 2003, 82, (12), 1531-1540. 17.

Wang, J.; Anthony, E. J., A study of thermal-cracking behavior of asphaltenes. Chemical

engineering science 2003, 58, (1), 157-162. 18.

Gray, M. R.; Ayasse, A. R.; Chan, E. W.; Veljkovic, M., Kinetics of hydrodesulfurization

of thiophenic and sulfide sulfur in Athabasca bitumen. Energy & fuels 1995, 9, (3), 500-506. 19.

Agarwal P; Sharma DK, Comparative studies on the biodesulfurization of crude oil with

other desulfurization techniques and deep desulfurization through integrated processes. Energy Fuels 2010, 24, 518-524. 20.

Barron, J.; Vanderploeg, A.; McReynolds, H., Sulfur Distribution in Thermal Cracking of

High-Sulfur Feed Stocks. Industrial & Engineering Chemistry 1949, 41, (12), 2687-2690. 21.

Hauser, A.; AlHumaidan, F.; Al-Rabiah, H., NMR investigations on products from

thermal decomposition of Kuwaiti vacuum residues. Fuel 2013, 113, 506-515. 22.

Potapenko, O. V.; Doronin, V. P.; Sorokina, T. P.; Talsi, V. P.; Likholobov, V. A.,

Transformations of thiophene compounds under catalytic cracking conditions. Applied Catalysis B: Environmental 2012, 117, 177-184. 23.

Yan, J.; Yang, J.; Liu, Z., SH radical: the key intermediate in sulfur transformation during

thermal processing of coal. Environmental science & technology 2005, 39, (13), 5043-5051. 24.

Muñoz, J. A.; Aguilar, R.; Castañeda, L. C.; Ancheyta, J., Comparison of Correlations for

Estimating Product Yields from Delayed Coking. Energy & Fuels 2013, 27, (11), 7179-7190. 25.

Stockman, L., Petroleum Coke: the coal hiding in the tar Sands. Oil Chance International,

Washington DC, USA 2013. 11 ACS Paragon Plus Environment

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 22

26.

Parkash, S., Refining processes handbook. Gulf Professional Publishing: 2003.

27.

Sawarkar, A. N.; Pandit, A. B.; Samant, S. D.; Joshi, J. B., Petroleum residue upgrading

via delayed coking: A review. The Canadian Journal of Chemical Engineering 2007, 85, (1), 124. 28.

Friday, J. In PD 20 (3) Production of High Quality Needle Coke, 9th World Petroleum

Congress, 1975. 29.

Asgharzadeh Shishavan, R.; Ghashghaee, M.; Karimzadeh, R., Investigation of kinetics

and cracked oil structural changes in thermal cracking of Iranian vacuum residues. Fuel Processing Technology 2011, 92, (12), 2226-2234. 30.

Sawarkar, A.; Pandit, A.; Joshi, J., Studies in coking of Arabian mix vacuum residue.

Chemical Engineering Research and Design 2007, 85, (4), 481-491. 31.

Yigezu, Z. D.; Muthukumar, K., Catalytic cracking of vegetable oil with metal oxides for

biofuel production. Energy Conversion and Management 2014, 84, 326-333. 32.

Jiao, Y.; Liu, A.; Li, C.; Wang, J.; Zhu, Q.; Li, X.; Chen, Y., Catalytic cracking of RP-3

jet fuel over wall-coated Pt/ZrO 2–TiO 2–Al 2 O 3 catalysts with different Al2O3 ratios. Journal of Analytical and Applied Pyrolysis 2015, 111, 100-107. 33.

Fu, X.; Shen, W.; Yao, T.; Hou, W., Physical chemistry Beijing. In China: China Higher

Education Press: 2006. 34.

Li, X.; Shen, B.; Xu, C., Interaction of titanium and iron oxide with ZSM-5 to tune the

catalytic cracking of hydrocarbons. Applied Catalysis A: General 2010, 375, (2), 222-229. 35.

Bortnovsky, O.; Sazama, P.; Wichterlova, B., Cracking of pentenes to C2–C4 light olefins

over zeolites and zeotypes: Role of topology and acid site strength and concentration. Applied Catalysis A: General 2005, 287, (2), 203-213.


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List of Figures Figure 1. Schematic diagram for experimental setup Figure 2. Number of bubbles discharging from gas scrubber vs. time


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11 12

13

14

10

9 2

3

4

6 5

1 7 8

Figure 1. Schematic diagram for experimental setup: (1) Nitrogen source; (2) Regulator; (3) Pressure gauge; (4) Needle valve; (5) Flow meter; (6) Check valve; (7) Autoclave; (8) Furnace; (9) Storage tank; (10) Condenser; (11) Thermometer; (12) Flow meter; (13) Back pressure regulator; (14) Gas scrubber.


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65

No. of bubble discharge in 30 sec.

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60 55 50 45 40 35 30 0

30

60

90

120

150

180

210

240

270

Time (min)

Figure 2. Number of bubbles discharging from gas scrubber vs. time (at 1 bar and 400°C)


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List of Tables Table 1. Properties of vacuum distillation residue from Abadan Refinery Table 2. Properties of iron oxide and aluminum oxide nanoparticles used as additives Table 3. Product yields at different reaction temperatures and pressures Table 4. Sulfur content of products at different reaction tepmeratures and pressures Table 5. Sulfur content and product yields at different concentration of nanoparticles Table 6. . Results of the repeatability of experimental sets


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Table 1. Properties of vacuum distillation residue from Abadan Refinery Property

Value ASTM test method

Kinematic Viscosity @ 100oC, cSt

572

D 2170

Kinematic Viscosity @ 135oC, cSt

107

D 2170

Specific Gravity @ 25/25oC

1.004

D 3289

Asphaltenes, mass%

4.3

SARA Test

Resins, mass%

22.3

SARA Test

Aromatics, mass%

50.1

SARA Test

Saturates, mass%

23.3

SARA Test

Pour Point, oC

>40

D 97

Conradson Carbon Residue, mass%

17.41

D 189

C content, mass%

86.1

D 5291

H content, mass%

10.4

D 5291

N content, mass%

0.5

D 5291

S content, mass%

3.35

D 4294

Vanadium (V), ppm

130

D 5863

Nickel (N), ppm

34

D 5863

Iron (Fe), ppm

2

D 5863


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Page 18 of 22

Table 2. Properties of iron oxide and aluminum oxide nanoparticles used as additives Nanoparticle

Purity

Average particle size

Specific surface area

Fe2O3 (III)

99.8%

20 – 30 nm

80 – 90 m2/g

Al2O3 (γ)

99%

< 30 nm

> 30 m2/g


Page 19 of 22

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Energy & Fuels

Table 3. Product yields at different reaction temperatures and pressures Pressure, bar

1

3 Coke

Liquid

5

Temperature/Product

Coke

Liquid

Gas

440 OC

28.33

57.56

14.11

*

*

460 OC

27.1

58.95

13.95

*

*

480 OC

26.33

60

13.67 28.78

50.92

20.3

28.95

39.53

31.52

500 OC

23.32

61.98

14.69 24.03

54.32

21.65

28.25

49.2

22.55

*experiments were not performed at these conditions


Gas

Coke

Liquid

Gas

Energy & Fuels

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Page 20 of 22

Table 4. Sulfur content of products at different reaction tepmeratures and pressures Pressure, bar

1

3 Coke

5

Temperature/Product

Coke

Liquid

Gas

Liquid

440 OC

5.81

1.63

5.43

*

*

460 OC

5.58

1.83

5.31

*

*

480 OC

5.56

1.84

5.76

5.53

1.51

4.88

500 OC

5.51

1.98

5.48

5.42

1.84

4.54

*experiments were not performed at these conditions


Gas

Coke

Liquid

Gas

5.3

1.46

3.95

5.11

1.53

5.12

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Energy & Fuels

Table 5. Sulfur content and product yields at different concentration of nanoparticles ppm

Liquid Yield (%)

Coke Yield (%)

Gas Yield (%)

Sulfur of Liquid (wt. %)

Sulfur of Coke (wt. %)

Sulfur of Gas (wt. %)

Selected Point

0

60

26.33

13.67

1.83

5.56

5.76

Al2O3

100

64.43

22.19

13.38

1.81

5.35

10.56

Al2O3

500

64.45

25.19

10.36

1.78

5.33

6.52

Al2O3

1000

66.44

23.56

10

1.76

5.21

7.78

Fe2O3

100

62.86

25.36

11.78

1.73

5.18

6.6

Fe2O3

500

66.67

23.47

9.86

1.68

5.09

8.81

Fe2O3

1000

62.99

24.68

12.33

1.68

5.09

7.04


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Page 22 of 22

Table 6. Results of the repeatability of experimental sets Experimental Pressure, bar

1

3

Coke, %

Liquid, %

Gas, %

1

26.33

60

13.67

2

26.21

60.09

13.7

1

28.78

50.92

20.3

2

28.43

51.08

20.49

set No.


Effect of Operating Conditions and Additives on the Product Yield and

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