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Cite This: Energy Fuels XXXX, XXX, XXX−XXX
Comments on “Key Performance Indicators Reveal the Impact of Demulsifier Characteristics on Oil Sands Froth Treatment” Indervir Shukla
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Scico Technologies, Karachi 75600, Pakistan ABSTRACT: In the paper titled “Key performance indicators reveal the impact of demulsifier characteristics on oil sands froth treatment” by Ishpinder Kailey, [Kailey, I. Key performance indicators reveal the impact of demulsifier characteristics on oil sands froth treatment. Energy Fuels 2017, 31, 2636−2642] the author emphasized the importance of interfacial tension (IFT) and relative solubility number (RSN) on the performance of demulsifiers in the oil sand froth treatment. However, the IFT data analyses were incorrect, which led to wrong conclusions. The reason why demulsifier performance is related to RSN was not explained. In addition, the paper has issues with the experimental method and literature citation.
T
Table 1. Dynamic and Static Interfacial Tension Values
here are many issues with the data analyses and conclusions in the paper titled “Key performance indicators reveal the impact of demulsifier characteristics on oil sands froth treatment” by Ishpinder Kailey.1 (1) The author claimed that a Baker Hughes proprietary method was used to measure the diluent loss. It is impossible for other researchers who read Kailey’s paper to know how the data was collected and assess whether the method and data are reasonable. In Kailey’s paper,1 the diluent loss is about 2% when the froth was treated by the demulsifier with the lowest relative solubility number (RSN) (Figure 8). Although the diluent losses in a blank sample (i.e., without demulsifier application) were not presented, they must be lower than 2% in the samples with demulsifier application because demulsifier application increases diluent losses on the basis of Kailey’s findings.2 In another recently published paper by Kailey,2 the diluent losses are around 5.5% in the blank sample (Figure 13), which is more than double compared with the 2% loss of this paper. The compositions of the bitumen froth reported in both papers are quite close: 57.16% bitumen, 33.13% water, and 9.71% solids (27.48% fines) in the current paper,1 compared with 56.57% bitumen, 34.19% water, and 9.24% solids in the other paper.2 Why are the diluent losses drastically different while bitumen froth compositions are so close? If the diluent losses are determined by other parameters, why were they not provided in the paper? (2) The author measured dynamic interfacial tension (IFT) at the toluene/water interface and static IFT at the diluted bitumen/water interface. The author claimed that series B demulsifiers had lower dynamic IFT values than series A demulsifiers and were more interfacially active than series A demulsifiers. These statements are not true. To clearly present the facts, the dynamic equilibrium IFT and static IFT values shown in Figures 1, 2, 5, and 6 were extracted and are listed in Table 1. In fact, the IFT values of B2, B3, and B4 are all higher than those of the corresponding A series (A2, A3, and A4, respectively), whereas the IFT value of B5 was the same as that of A5 and the IFT value of B1 was slightly lower than that of A1. Therefore, it is false © XXXX American Chemical Society
series
demulsifier
RSN
dynamic IFT mN/m
static IFT mN/m
A
A1 A2 A3 A4 A5 B1 B2 B3 B4 B5
8.7 10.7 12.6 15.8 21.3 7.3 8.6 10.6 14.8 20.7
16.5 13.0 9.0 10.0 6.5 15.5 14.0 11.0 11.0 6.5
25.0 21.0 19.8 17.4 16.8 22.2 21.2 19.6 18.3 16.5
B
to state that series B demulsifiers had lower dynamic IFT values than series A demulsifiers. In addition, the static IFT values of series B demulsifiers are nearly the same as those of the corresponding series A demulsifiers, with the only exception of the IFT of B1 being lower than that of A1. Hence, the dynamic as well as static IFT values of both series are quite close, indicating similar interfacial activity. Thus, the statement that series B demulsifiers performed better than series A demulsifiers due to the lower IFT values of series B in the Abstract and Conclusions section is incorrect. (3) The core focus of Kailey’s paper is the correlation between key performance indicators (KPIs) and RSN, which is shown as KPIs as a function of RSN in Figures 3−9. The author reported that demulsifier performance increased with increasing RSN in a very wide range from 7.3 to 20.7 (A series) and 8.7 to 21.3 (B series). In fact, the relationship between demulsifier performance and RSN has been reported in the literature. Xu et al.3 found that the optimum performance was achieved at RSN of 18−22 corresponding to propylene oxide (PO)/ethylene oxide (EO) of 1.0−1.8. Berger et al.4 found that there was no correlation between RSN and demulsifier performance Received: December 16, 2018 Revised: February 14, 2019 Published: February 19, 2019 A
DOI: 10.1021/acs.energyfuels.8b04347 Energy Fuels XXXX, XXX, XXX−XXX
Energy & Fuels
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after performing 2400 field bottle tests. Wu et al.5 observed that the best demulsifier performance was achieved at RSN of 7.5−12.5 with molecular weight (MW) of 7500−15 000. Kailey was supposed to explain why the KPIs depended on RSN and to compare his/her findings with the literature. Unfortunately, Kailey presented data without explaining why KPIs depend on RSN. Kailey1 referenced the papers by Berger et al.4 and Wu et al.5 but omitted their findings on the effect of RSN on demulsifier performance.1 Moreover, in the Conclusions section of the paper by Berger et al.,4 the fourth conclusion is “no correlation exists between RSN, hydrophilic−lipophilic balance (HLB), or hexane acetone titration and demulsifier performance”. In the Introduction section of Kailey’s paper,1 Berger’s paper was cited in the sentence “the proficiency of a demulsifier is primarily measured by its HLB and the capability to destroy the film at the O/W interface”. Evidently, the author completely changed the conclusion of Berger’s paper that he/she referenced, which is unethical.
Article
AUTHOR INFORMATION
ORCID
Indervir Shukla: 0000-0003-4553-9838 Notes
The author declares no competing financial interest.
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REFERENCES
(1) Kailey, I. Key performance indicators reveal the impact of demulsifier characteristics on oil sands froth treatment. Energy Fuels 2017, 31, 2636−2642. (2) Kailey, I.; Behles, J. Evaluation of the performance of newly developed demulsifiers on dilbit dehydration, demineralization, and hydrocarbon losses to tailings. Ind. Eng. Chem. Res. 2015, 54, 4839− 4850. (3) Xu, Y.; Wu, J.; Dabros, T.; Hamza, H.; Wang, S.; Vidal, M.; Venter, J.; Tran, T. Optimizing the PPO/PEO contents in DET-based surfactants for destabilization of a W/O emulsion. Can. J. Chem. Eng. 2004, 82, 829−835. (4) Berger, P. D.; Hsu, C.; Arendell, P. In Designing and selecting demulsifiers for optimum field performance based on production fluid characteristics, Proceedings of International Symposium on Oilfield Chemistry, San Antonio, TX, SPE 16285, 1987; pp 457−464. (5) Wu, J.; Xu, Y.; Dabros, T.; Hamza, H. Effect of demulsifier properties on destabilization of W/O emulsion. Energy Fuels 2003, 17, 1554−1559.
(4) In addition to the major issues mentioned above, there are more problems with the paper. Some of Kailey’s statements and data are unreliable because the provided information about the demulsifiers used was insufficient. For example, Kailey1 discussed the effect of MW on demulsifier performance, even though MWs were provided for only 4 out of 10 demulsifiers. Kailey1 stated in the abstract that two series (A and B) of EO−PO block copolymers were synthesized and studied. However, the author did not synthesize the demulsifiers in his/her work as the author stated that the demulsifiers were supplied from other people in the Materials and Methods section. Furthermore, the details of the synthesis of the demulsifiers were not provided. Kailey1 stated that the EO in the EO block of the demulsifiers varied from 0 to 40%. We do not know if the 40% is by weight in the molecule or by mole in the total EO and PO. When the EO content is zero, A1 and B1 have a MW of 4000 and 8000, respectively. Because they have the same starting base material and no EO, the MW difference of 4000 is solely due to the PO. In other words, B1 has 69 (4000 divided by the molar mass of propylene oxide, 58) more moles of PO than A1. Although it has such a high PO content with no EO, B1 demonstrated relatively strong interfacial activity and achieved >30% dehydration efficiency at 25 ppm and 30 min retention time. On the basis of the EO and PO contents of B1, the performance of B1 is dubious. Kailey did not discuss the experimental error for water removal, solids removal, diluent loss, RSN, and IFT data at all in his/her paper.1 The slight difference between the IFT results may be purely due to experimental noise. In the abstract, Kailey stated that “the demulsifiers were defined by relative solubility number (RSN) and interfacial tension (IFT)”. IFT is not a material property. It is a time-dependent value and is system dependent. How can the author define a demulsifier by its IFT? In conclusion, the author used undisclosed methods to study demulsifiers of undisclosed structures. Clearly, the author arrived at false conclusions by using misleading and questionable analyses as well as presenting direct observations lacking any scientific explanation. B
DOI: 10.1021/acs.energyfuels.8b04347 Energy Fuels XXXX, XXX, XXX−XXX
