Evaluation of the Performance of Newly Developed Demulsifiers on

Apr 15, 2015 - PSD data shows that demulsifier Y reduced most of the particles of size less than 0.50 μm from the interface. Therefore, demulsifier Y...
0 downloads 9 Views 4MB Size
Download PDF
Article pubs.acs.org/IECR

Evaluation of the Performance of Newly Developed Demulsifiers on Dilbit Dehydration, Demineralization, and Hydrocarbon Losses to Tailings Ishpinder Kailey* and Jacqueline Behles Baker Hughes, 7020 45th Street, Leduc, Alberta, Canada T9E 7E7 ABSTRACT: The oil sands industry is continuously looking for demulsifiers that effectively dehydrate and demineralize diluted bitumen, minimize rag layer formation by controlling oil/water interface, and reduce naphtha and bitumen losses to tailings. In this paper, the performance of two newly developed demulsifiers, “X” and “Y”, were evaluated on the basis of diluted bitumen (dilbit) dehydration, demineralization, and naphtha and bitumen losses to tailings. The results demonstrate that the water removal efficiency of demulsifier Y is 14.15% higher than that of demulsifier X at 50 ppm dosage after 15 min of settling time. The solids removal efficiencies of demulsifiers X and Y at 50 ppm dosage after 15 min settling time, for the top dilbit fraction, were 13.9 and 21.5%, respectively. Demulsifier Y reduced the diluent and bitumen losses to the underflow by 16.7 and 13.8%, respectively, at 50 ppm dosage after 15 min of residence time as compared to demulsifier X. Therefore, demulsifier Y performed superior on all the key performance indicators (KPIs) studied as compared to demulsifier X. To determine the reason why the performance of demulsifier Y is superior to that of demulsifier X on all the KPIs, solids were collected from the original froth and the top, interface, and bottom fractions of the diluted froth after demulsification tests and characterized by X-ray diffraction analysis (XRD), X-ray energy dispersive spectrometry, scanning electron microscopy, particle size distribution (PSD), and wettability studies. XRD data shows that demulsifier Y reduced the clays, iron, and zirconium oxide minerals from the top and interface dilbit fractions when compared to the control sample. PSD data shows that demulsifier Y reduced most of the particles of size less than 0.50 μm from the interface. Therefore, demulsifier Y helps to resolve the interfacial material by removing the minerals that tend to form a rag layer, especially siderite, pyrite, magnetite, rutile, and anatase, from the oil/water interface to the underflow. to flow into either bitumen stream or tailings stream, and can ultimately halt the whole process if not managed properly.11 To meet oil sands industry requirements, mechanical or/and chemical techniques are employed to resolve water-in-diluted bitumen emulsions. The chemical approach is proven to be more cost-effective and technically feasible. In this approach the demulsifier modifies the interfacially active properties and displaces the interfacial materials from the interface. However, the co-occurrence of solids in the oil/water emulsions makes demulsification challenging.12 In bitumen froth treatment, the oil sands industry continually searches for demulsifiers, which effectively dehydrate and demineralize the diluted bitumen and reduce the hydrocarbon losses to tailings. In general, demulsifiers are blends of numerous polymers and comprise an extensive molecular weight distribution to meet all the key performance indicators (KPIs), such as dehydration and demineralization of the diluted bitumen, and hydrocarbon losses to tailings. Each constituent in a demulsifier formulation has a different partitioning ability and interfacial activity. In this paper we evaluated the performance of two newly developed demulsifiers, “X” and “Y”, on dilbit dehydration, demineralization, and naphtha/bitumen losses to tailings. Each constituent of the final demulsifier formulation

1. INTRODUCTION In oil sands mining operations, bitumen can be liberated via the flotation method, where the oil-enriched ore is mixed with hot water at 85 °C in the presence of caustic soda. Oil liberated from the oil sands rises to the top of the flotation vessel as bitumen froth with the aid of air bubbles. The bitumen froth typically comprises about 60 wt % bitumen, 30 wt % water, and 10 wt % solids. In a typical process, diluent is added to bitumen froth to reduce viscosity to further lessen the water and solids contents. The paraffinic and naphtha-based are two main processes currently being used to treat the bitumen froth. In the paraffinic process, a proportion of diluent to bitumen (D/B) over two is preferred, and the diluted bitumen contains an overall water and solids contents below 0.1 wt %.1−3 While in the naphtha-based process, at D/B of 0.6 to 0.75, the diluted bitumen typically comprises about 2−5 wt % water and 0.3−1 wt % solids.4,5 The interfacial active materials like clays, resins, asphaltenes, and naphthenic acids create a firm film at the oil/water interface, inhibiting coalescence among the water droplets.6−9 It is vital to eliminate the emulsified water and solids from the diluted bitumen because the dissolved salts in water pose serious corrosion issues to the pipelines and processing facilities. Furthermore, emulsified water and solids form a rag layer at the oil/water interface.10,11 The rag layer comprises multiple emulsions stabilized by a slight portion of asphaltenes.5,10 The untreated rag layer can widen to a size © 2015 American Chemical Society

Received: Revised: Accepted: Published: 4839

February 3, 2015 April 8, 2015 April 15, 2015 April 15, 2015 DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

2.4. Interfacial Tension Measurement. Fisher Scientific Semiautomatic Model 21 Tensiomat Tensiometer and Pt/Ir ring technique was employed for interfacial tension measurements. 60 wt % toluene-diluted bitumen and deionized (DI) water were used as oil and aqueous phases, respectively. Demulsifier was added in the oil phase. All of the investigations were accomplished at 20.0 ± 0.5 °C. 2.5. Solids Extraction. The known amount of diluted froth samples from top and interface fractions were transferred into weighed Teflon centrifuge tubes and centrifuged at 15,000 rpm for 30 min using a Beckman Coulter Optima L-90K ultracentrifuge. After 30 min the top oil from centrifuge tubes was carefully removed with plastic pipettes. The centrifuge tubes containing solids were filled with toluene, sonicated until the solids entirely dispersed, and centrifuged. The sonication and centrifugation stages were reiterated until the supernatant was clear. The solids were dried at 115 °C for 2 h in an oven. The tubes containing dry solids were reweighed to calculate the percent solids in diluted froth samples. The demineralization or solids removal efficiency of demulsifiers X and Y for each dosage was calculated from

was carefully selected so that the combined demulsifier package meets all the KPIs.

2. MATERIALS AND METHODS 2.1. Materials. The mineable oil producers from Athabasca region provided fresh bitumen froth, naphtha, and vacuum distillation feed bitumen. The Dean−Stark extraction method was used to determine the components of the bitumen froth. The composition of froth averaged approximately 56.57 ± 0.17 wt % bitumen, 34.19 ± 0.32 wt % water, and 9.24 ± 0.04 wt % solids. Toluene and ethylene glycol dimethyl ether used for interfacial tension (IFT) and relative solubility number (RSN) measurements, respectively, were obtained from Fisher Scientific. 2.2. Demulsifiers. Baker Hughes Evan Ginn Research and Development Centre in Sugar Land, Texas supplied the demulsifiers for this work. Two demulsifier formulations, X and Y, were prepared and studied in the Baker Hughes Oil Sands Laboratory in Leduc, Alberta. RSN values of demulsifiers X and Y were measured at 9.32 and 9.50, respectively. The details of the RSN determination method can be found in ref 13. 2.3. Demulsification Tests. The bottle tests were used to simulate the demulsification performance of inclined plate settlers and settling tanks. The bitumen froth was heated to 80 °C in a water bath and then homogenized using a motor-driven stirrer in a water jacketed stainless steel beaker. The homogenized froth was then split into about 90 g subsamples in a set of numbered bottles. The naphtha was also homogenized at room temperature using a paint shaker and then split into subsamples at naphtha-to-bitumen proportion of 0.6. The bitumen froth and naphtha samples were placed in water bath at 80 °C for 30 min. The naphtha samples were transferred to the respective bitumen froth samples, and after being dosed with the demulsifier, the naphtha diluted froth samples were shaken on a horizontal shaker at high speed for 6 min. The demulsifier dosage was based on the bitumen content of the froth. Two undosed bottle tests were controls in each set of bottle tests. The bottles were placed back in a water bath and allowed to settle under gravity. Diluted froth samples were collected at the 1/3 height from the surface at 15 min from each bottle, and the water content was measured by a Karl Fisher titration. The average water content in the two control tests was used as a reference point. The dehydration or water removal efficiency of demulsifiers X and Y for each dosage was calculated from dehydration efficiency (%) =

(Wo − Wd) × 100 Wo

demineralization efficiency (%) =

(So − Sd) × 100 So

(2)

where So is the solids content in the control test and Sd is the solids content on addition of the demulsifier. The results indicated for each dosage are the average of three measurements. The solids from the froth and bottom fraction of diluted froth were collected from a Dean−Stark analysis. The clean solids from the froth and the top, interface, and bottom fractions were characterized using X-ray diffraction analysis (XRD), X-ray energy dispersive spectrometry (EDS), scanning electron microscopy (SEM), particle size distribution (PSD) and wettability studies. 2.6. Optical Microscopy. Micrographs of emulsions were obtained using an Olympus BX51 microscope. The samples were taken at the 1/3 height of the diluted froth from the top surface and above the oil/water interface for a control run and the diluted froth treated with 50 ppm of demulsifiers X and Y. 2.7. Characterization of Solids. The diffraction patterns of the minerals were obtained by using a Rigaku Ultima IV Xray diffractometer incorporated with cross beam optics (CBO) technology equipped with cobalt X-ray source (Co Kα) and D/ teX detector. The solids were disseminated in deionized (DI) water and moved on a quartz plate. Preceding each measurement, the water was evaporated by heating at low temperature. TOPAS software was employed for the quantitative phase analysis of the minerals prevailing in the randomly oriented sample. Rietveld analysis was performed using the PDXL program provided with the diffractometer to determine the existing minerals by weight percent. Inorganic Crystal Structure Database (ICSD) was used for records of inorganic crystal structures. EDS was conducted using an Oxford Instruments INCA Xact detector. PSD measurements were performed with a JEOL JSM-6600 SEM instrument using Image Pro software. The particles were sputter-coated with gold in a vacuum chamber prior to SEM measurement. The reported frequency of a particle size represents the number of particles with that size in a total of 500 particles measured.

(1)

where Wo is the water content in the control test and Wd is the water content on the addition of the demulsifier. The results indicated for each dosage are the average of three measurements. After 15 min of settling, the diluted froth samples in each bottle are distributed into three fractions for mineralogy studies. About 60 mL of diluted froth samples collected at 1/3 height from the top surface is called the “top fraction”. The next 20 mL of diluted froth samples collected above the oil/water interface is called the “interface fraction”. The remaining dilbit at the interface and on the inner walls of the bottle was carefully removed. The residual fluid left in the bottle is called “bottom fraction”. 4840

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research The film flotation technique was practiced to measure quantitatively the solids wettability.11,14,15 A methanol−water mixture is used as the analytical liquid. The surface tension was measured at different methanol−water mole fractions. For wettability measurements, solids from the interface fractions for control run and after demulsification with demulsifier Y were washed with excess toluene and then dried. 2.8. Underflow Preparation. The underflow was prepared to measure the effect of demulsifiers X and Y on bitumen and diluent losses to tailings. After 30 min of settling, the bottles were removed from the water bath and the diluted bitumen phase was removed cautiously above the free water at oil/water interface. The fluid left in the bottle is called the underflow. 2.9. Hydrocarbon Loss Measurement. Diluent losses to the underflow were measured by the use of the Baker Hughes proprietary method. Bitumen losses to the underflow were calculated by the Dean−Stark extraction method. The underflow prepared according to the procedure described in section 2.8 was displaced to a Soxhlet extraction thimble and constantly extracted with toluene. The amount of bitumen lost to the underflow was evaluated using a filter paper method.

diluted froth in both the top and interface fractions has fewer solids and less water in the presence of Y as compared to X. To find the correlation between the dehydration efficiencies of demulsifiers and their IFT, the IFT between DI water and 60 wt % toluene-diluted bitumen was considered in the absence and presence of demulsifiers X and Y. Figure 4 shows the correlation between the IFT and demulsifier dosage. Figure 4 indicates that the IFT decreases as the demulsifier dosage increases and also IFT values are lower in the presence of demulsifier Y. Thus, the demulsifier Y led to lowest IFT (Figure 4) and the highest water removal efficiencies (Figure 1) in the dosage range studied. Numerous researchers have made an effort to relate demulsification performance with IFT. Bhardwaj and Hartland report the rapid partitioning of the demulsifier at the oil/water interface, decreased IFT, and improved demulsification efficiency.16 Byoung et al. found the inverse relation between IFT and the dehydration efficiency with the increase in the demulsifier concentration.17 Even though a converse relation was established between dehydration efficiency and IFT herein, other aspects should be measured when choosing a demulsifier formulation. 3.2. Effect on Solids Content. The solids content of the dilbit samples collected from the top and interface fractions after 15 min of residence time were determined by high-speed centrifugation. Figures 5 and 6 show the relation between the demulsifier concentration and solids extracted from the top and interface diluted bitumen fractions, respectively. The performance of demulsifier Y was superior to that of X for solids removal from the top and interface dilbit fractions over the dosage range studied. The solids removal efficiencies of demulsifiers X and Y when using 15 ppm demulsifier for the top dilbit fraction were 7.69 and 12.3%, respectively. However, at 50 ppm dosage, the solids removal efficiencies of demulsifiers X and Y were 13.9 and 21.5%, respectively. The solids removal efficiency of demulsifier Y is 7.6% higher than that of X at 50 ppm dosage for the top dilbit fraction. The results reveal that both the demulsifiers are reducing the solids content from both the top and interface fractions of diluted froth. However, the performance of demulsifier Y on solids removal from both the top and interface fractions of diluted froth was relatively better than that of demulsifier X over the dosage range studied. The solids collected from the froth and top, interface, and bottom fractions after demulsification with demulsifiers X and Y were characterized with XRD, EDS, SEM, PSD, and wettability studies and compared against those collected from the control run (no demulsifier). The composition of the solids was examined using XRD analysis and is summarized in Figure 7. Figure 7A shows the relative abundance of minerals in the solids collected from the top fraction of demulsification test at 15 min of residence time for control test and in the presence of 50 ppm demulsifiers X and Y. The XRD data demonstrates that the performance of of demulsifier Y was superior to that of demulsifier X in the removal of minerals such as microcline, clinoclore, pyrite, anatase, siderite, and zirconium oxide from the top fraction. Demulsifier Y decreased the microcline, clinochlore, siderite, pyrite, anatase, and zirconium oxide by 57, 41.7, 3.1, 27.6, 9.1, and 38.9%, respectively, in the top fraction as compared to the control test (no demulsifier). Demulsifier X reduced the microcline, clinochlore, siderite, pyrite, anatase and

3. RESULTS AND DISCUSSION To measure the performance of chemical demulsification, the typical KPIs are the water content and the solids content in the diluted bitumen products and bitumen/diluent losses to the tailings. The lower the value of the KPIs reached, the better the performance of the froth treatment. 3.1. Effect on Water Content. Demulsification of the froth samples was performed at the rates of 0, 15, 30, and 50 ppm of either demulsifier X or Y. The water contents of the dilbit were examined at 15 min of residence time using a Karl Fischer titrator and plotted against the demulsifier dosage, as shown in Figure 1. Figure 1 shows that Y is consistently better than X

Figure 1. Correlation between percent water content of diluted bitumen and demulsifier dosage.

over the dosage range studied. The dehydration efficiencies of Y are 1.20, 5.20, and 14.15% higher than those of X at 15, 30, and 50 ppm dosages, respectively, after 15 min of residence time. Figures 2 and 3 show the light micrographs for the diluted froth from the top and interface fractions, respectively, for a control run and the diluted froth treated with 50 ppm of demulsifiers X and Y at 15 min of residence time. These micrographs noticeably demonstrate that demulsifiers X and Y are separating the water and solids from the top and interface fractions as compared to the control run. Both the size and the number of water droplets decreased after demulsification. The 4841

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 2. Micrographs of diluted froth samples collected at the 1/3 height from the top surface at 80 °C after 15 min of residence time: (A) control run, (B) 50 ppm demulsifier X, and (C) 50 ppm demulsifier Y. All images were taken in bright field. The scale bar in each image indicates 20 μm.

Figure 7 also reveals that the total clay content (i.e., kaolin, illite, albite, microcline, and clinochlore) decreased in the top fraction, but increased in the interface and bottom fractions. In the control test the total clay contents are 25.5, 23.3, and 17 wt % in top, interface, and bottom fractions, respectively. The presence of 50 ppm of demulsifier Y reduced the total clay content in the top fraction by 12.5%. These clays fall to the interface and bottom layers and hence increase the clay contents by 25.3 and 24.1%, respectively, in the interface and bottom fractions. Figures 7(A) and 7(B) show that the minerals kaolin, illite, and clinochlore are decreasing in the top fraction and increasing in the interface fraction at 15 min of settling time in the presence of 50 ppm of demulsifier Y. These results illustrate that these clays are falling toward the bottom in the demulsification test and 15 min of residence time might not be enough for all the solids to completely separate to the bottom phase. Figure 8 shows the elemental distribution in solids collected from the top, interface, and bottom fractions of demulsification tests at 15 min of residence time. Figure 8A reveals that demulsifier Y decreased elements such as magnesium (Mg), aluminum (Al), silicon (Si), potassium (K), calcium (Ca), titanium (Ti), iron (Fe), zirconium (Zr), manganese (Mn), and copper (Cu) by 15.4, 30.1, 29.7, 37.3, 19.2, 40.5, 36.4, 14.3, 34.6, and 30.8%, respectively, by weight from the top fraction after 15 min of residence time at 50 ppm dosage. In contrast, 50 ppm demulsifier X at 15 min of residence time reduced Al, Si,

zirconium oxide by 30.4, 8.3, 2.8, 12.2, 3.0, and 19.4%, respectively, in the top fraction as compared to the control test. Figure 7B illustrates the relative abundance of minerals in solids collected from the interface fraction of demulsification test at 15 min of residence time for control test and in the presence of 50 ppm demulsifiers X and Y. The XRD data indicates that both demulsifiers X and Y targeted minerals such as siderite, pyrite, anatase, rutile, anhydrite, albite, and microcline at the interface, but demulsifier Y showed higher performance than X. Figure 7B shows that at 50 ppm dosage and 15 min of settling time demulsifier Y removed 61.7 and 54.7% of siderite and pyrite, respectively, whereas demulsifier X removed 43.7 and 31.3% of siderite and pyrite, respectively, from the interface. These iron materials are known to be surface active and would accumulate at the interface, causing rag buildup.17 Thus, demulsifier Y helps to resolve the iron minerals that are known to form a rag layer. Demulsifier Y reduced the titanium oxide minerals, such as anatase and rutile, by 32.6 and 35%, respectively, at the interface while demulsifier X reduced anatase and rutile by 23.9 and 16.2%, respectively. Figure 7C illustrates the relative abundance of minerals collected from the bottom fraction of the demulsification test at 15 min of residence time for control test and in the presence of 50 ppm demulsifiers X and Y. These results reveal that both demulsifiers X and Y facilitated the separation of every mineral from the froth to the bottom layer. 4842

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 3. Micrographs of diluted froth samples collected above oil/water interface at 80 °C after 15 min of residence time: (A) control run, (B) 50 ppm demulsifier X, and (C) 50 ppm demulsifier Y. All images were taken in bright field. The scale bar in each image indicates 20 μm.

Figure 4. Correlation between interfacial tension and demulsifier dosage in water/60 wt % toluene-diluted bitumen.

K, Ca, Ti, Fe, Zr, Mn, and Cu by 21.1, 13.6, 60.0, 3.3, 29.4, 24.01, 28.6, 24.2, and 25.0%, respectively, by weight from the top fraction. These EDS results show that demulsifier Y outperformed on heavy metals removal and also justify the removal of minerals such as microcline [KAlSi3O8], clinochlore [(Mg,Fe,Al)6(Si,Al)4O10(OH)2], siderite [FeCO3], pyrite [FeS2], anatase [TiO2], and zirconium oxide [ZrO2] by demulsifiers (shown in Figure 7A) from the top fraction demulsification test solids.

Figure 8B shows elemental distribution in solids collected from the interface fraction. Figure 8B illustrates that demulsifier Y reduces the elements such as Ti, Fe, and Zr by 24.8, 33, and 100%, respectively, by weight from the interface fraction after 15 min of residence time with a 50 ppm dosage. On the other hand, demulsifier X removed the heavy metals Ti, Fe, and Zr by 16.2, 8.0, and 100%, respectively, at 15 min and 50 ppm dosage. These results justify the removal of minerals such as siderite, pyrite, anatase, rutile [TiO2], and zirconium oxide shown in 4843

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 5. Correlation between the demulsifier concentration and solids extracted from the top diluted bitumen fraction.

Figure 6. Correlation between the demulsifier concentration and solids extracted from the interface diluted bitumen fraction.

Figures 9 and 10 show the SEM photomicrographs for the solids in the top, interface, and bottom fractions in the control run and in the presence of 50 ppm of demulsifier Y, respectively, at 15 min of settling time. The scale bar in all the SEM photomicrographs is 50 μm. SEM photomicrographs show that all the samples consist of aggregates of angular, subangular, and subrounded, clay size to coarse sand size particles. Figure 9 demonstrates the top and interface fractions are more crowded with solids than the bottom fraction. Demulsifier Y helped to separate the solids from the top and interface fractions to the bottom fraction, as shown in Figure 10. Hence, the demulsification with 50 ppm of demulsifier Y helped clean the top and interface fractions. Particle size analysis was conducted on the SEM photomicrographs. The particle size of solids was measured using the Image Pro Plus software using 500 particles analyzed in each tests fraction. The particle size histogram for the solids collected from the interface fraction from the control test and in the presence of demulsifiers X and Y is shown in Figure 11. Demulsifier Y at 50 ppm dosage and 15 min of settling time separated most of the particles of size less than 0.50 μm from the interface.

Figure 7B by both demulsifiers, but Y performed superior to X for removal of Fe and Ti from the interface fraction demulsification test solids. In addition, the XRD results for iron are greater than the EDS results, which indicate the iron occurs in crystalline compounds. For instance, the EDS analysis detected 33 wt % iron removal from the interface fraction, while XRD analysis detected 62.2 wt % iron removal by demulsifier Y. Figure 8C shows the elemental distribution of the solids collected from the bottom fraction of demulsification tests after 15 min of residence time. The elemental distribution illustrates that the concentration of all the elements is increasing in the bottom fraction after demulsification in the presence of 50 ppm of demulsifiers X or Y. The reduction of minerals in the top fraction is evident as the minerals are increasing in bottom fractions; the elemental composition also increases as shown in Figures 7C and 8C. Comparison of panels A and B of Figures 8 shows that the elements Al, K, Ca, and Cu are decreasing in the top fraction and increasing in the interface fraction after 15 min of residence time in the presence of 50 ppm of demulsifier Y. These results illustrate that the solids are settling out toward the bottom fraction during demulsification and the 15 min of residence time might not be enough for all the solids to completely separate to the bottom phase. 4844

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 7. Relative abundance of minerals determined by XRD in solids collected from the (A) top fraction, (B) interface fraction, and (C) bottom fraction.

Figure 12 presents the percentage of floating solids isolated from the interface fractions for control run and after demulsification with demulsifier Y. The solids flotability is influenced by their dimensions and wetting properties, which means that small hydrophobic solids will drop in higher methanol ratios. In pure water, 100% of the solids collected from the interface fraction of the control test floated, in contrast to 87.4% from the interface fraction in the presence of

demulsifier Y. These results indicate that the solids in the interface fraction of the control run are more hydrophobic than those collected from samples in the presence of demulsifier Y. XRD data also indicated that the demulsifier Y separated the hydrophobic solids, such as siderite, pyrite, magnetite, albite, anatase, and rutile, from the interface fraction. Upon decreasing the surface tension by increasing methanol mole fraction, all the solids from the interface fraction of the control test floated until 4845

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 8. Relative abundance of metals in solids collected from the (A) top fraction, (B) interface fraction, and (C) bottom fraction.

56.2 mN/m, known as the higher wetting surface tension.15 Further decrease in surface tension by methanol addition decreased the percentage of floating solids both in the absence and presence of demulsifier Y until 26.8 mN/m, at which point 100% of the solids dropped, identified as the lower wetting surface tension.15 3.3. Effect on Hydrocarbon Losses to Underflow. The diluent losses to underflow were determined by using the Baker Hughes proprietary method. The diluent losses are expressed as a percentage of the diluent collected by the Baker Hughes method to the original amount of diluent added to the test sample. The values presented in this section are indications

only and cannot be correlated to the actual system because the test system cannot simulate the downstream processing equipment used by mining operators, such as hydrocyclones and the naphtha recovery units that further reduce the hydrocarbon losses to tailings. Therefore, the data presented shows losses higher than those that would be expected in the commercial plant. The important point to note is that comparisons can be made between the different demulsifiers to show the same, better, or worse performance on losses to the underflow. The diluent losses to the underflow as a function of demulsifier dosage are shown in Figure 13. Demulsifier Y 4846

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 9. SEM images for the solids from the top, interface, and bottom fractions after demulsification for the control test (no demulsifier) after 15 min of residence time.

also showed superior performance as compared to demulsifier X on the bitumen losses to the underflow. Demulsifier Y reduced the bitumen losses to the underflow by 12.6 and 13.8% by weight, as compared to demulsifier X at 30 and 50 ppm, respectively, after 15 min of residence time. These results show that the incorporation of the chemistries in demulsifier Y exhibited substantial improvement on lowering the bitumen losses as compared to demulsifier X.

showed superior performance with lower diluent losses to the underflow as compared to that of demulsifier X. Demulsifier Y reduced the diluent losses to the underflow by 9.2 and 16.7% by weight as compared to demulsifier X at 30 and 50 ppm, respectively, after 15 min of residence time. These results reveal that the incorporation of the new chemistry in demulsifier Y showed a significant improvement in reducing the diluent losses as compared to demulsifier X. The correlation between bitumen losses to the underflow and demulsifier dosage is shown in Figure 14. Demulsifier Y 4847

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 10. SEM images for the solids from the top, interface, and bottom fractions after demulsification in the presence of 50 ppm demulsifier Y after 15 min of residence time.

4. CONCLUSIONS

demulsifier X. The dehydration and demineralization efficiencies of demulsifier Y are 14.15 and 7.6%, respectively, higher than those of demulsifier X at 50 ppm dosage and 15 min of settling time. XRD analysis of solids collected after

Demulsifier Y performed in a superior manner on all the KPIs of demulsification, such as dilbit dehydration, demineralization, and hydrocarbon losses to the underflow, as compared to 4848

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research

Figure 11. Comparison of the particle size histogram for the solids collected from the interface fraction for the control test and in the presence of 50 ppm of demulsifiers.

Figure 14. Correlation between percent bitumen loss to the underflow and demulsifier dosage. Figure 12. Correlation between percentage of floating solids and methanol/water surface tension.

the interface fraction. Compared to demulsifier X, demulsifier Y helped to reduce the diluent and bitumen losses to the underflow by 16.7 and 13.8%, respectively, at 50 ppm dosage after 15 min of settling time.

■

AUTHOR INFORMATION

Corresponding Author

*Phone: (780) 980-5978. Fax: (780) 980-5989. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS The authors thank our colleagues in the Baker Hughes Evan Ginn Research & Development Center, Sugar Land, Texas and in Fort McMurray, Alberta for their valuable support. We also thank Larry Sartori and Mark Williams for their valuable suggestions. The permission from Baker Hughes to publish this paper is greatly appreciated.

Figure 13. Correlation between percent diluent loss to the underflow and demulsifier dosage.

demulsification with Y at 50 ppm dosage after 15 min of settling time decreased microcline, clinochlore, siderite, pyrite, anatase, zirconium oxide, and the total clay content by 57, 41.7, 3.1, 27.6, 9.1, 38.9, and 12.5%, respectively, from the top fraction; and siderite, pyrite, magnetite, microcline, albite, anatase, and rutile by 61.7, 54.7, 70.8, 29.0, 54.5, 32.6, and 35%, respectively, from the interface fraction, as compared to the control test. PSD data demonstrates that demulsifier Y separated most of the particles of size less than 0.50 μm from

■

REFERENCES

(1) Sheltantook, W. E. A perspective on the selection of froth treatment processes. Can. J. Chem. Eng. 2004, 82, 704−709. (2) Tipman R. N.; Long, Y.; Shelfantook, W. Solvent process for bitumen separation from oil sands froth. U.S. Patent 6,214,213 B1, 2001.

4849

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850

Article

Industrial & Engineering Chemistry Research (3) Long, Y. C.; Dabros, T.; Hamza, H. Stability and settling characteristics of solvent-diluted bitumen emulsions. Fuel 2002, 81, 1945−1952. (4) Long, Y. C.; Kan, J.; Walker, A.; Dabros, T. Process for treating heavy oil emulsions using a light aliphatic solvent-naphtha mixture. Canada Patent 2,435,113, 2005. (5) Czarnecki, J. Water-in-oil emulsions in recovery of hydrocarbons from oil sands. In Encyclopedic Handbook of Emulsion Technology; Sjoblom, J., Ed.; Marcel Dekker: New York, 2001; pp 497−514. (6) Yan, Z.; Elliott, J. A. W.; Masliyah, J. H. Roles of various bitumen components in the stability of water-in-diluted bitumen emulsions. J. Colloid Interface Sci. 1999, 220, 329−337. (7) Gao, S.; Moran, K.; Xu, Z.; Masliyah, J. Role of bitumen components in stabilizing water-in-diluted oil emulsions. Energy Fuels 2009, 23, 2606−2612. (8) Wu, X. Investigating the stability mechanism of water-in-diluted bitumen emulsions through isolation and characterization of the stabilizing materials at the interface. Energy Fuels 2003, 17, 179−190. (9) Wu, X. A. Selective Creaming: A novel technique to isolate interfacial organics and mineral solids from water-in-oil emulsions. Energy Fuels 2008, 22, 2346−2352. (10) Czarnecki, J.; Moran, K.; Yang, X. On the “Rag layer” and diluted bitumen froth dewatering. Can. J. Chem. Eng. 2007, 85, 748− 755. (11) Saadatmand, M.; Yarranton, H. W.; Moran, K. Rag layers in oil sand froths. Ind. Eng. Chem. Res. 2008, 47, 8828−8839. (12) Sztukowski, D. M.; Yarranton, H. W. Characterization and interfacial behavior of oil sands solids implicated in emulsion stability. Sep. Sci. Technol. 2004, 25 (3), 299−310. (13) Wu, J.; Xu, Y.; Dabros, T.; Hamza, H. Development of a method for measurement of relative solubility of nonionic surfactants. Colloids Surf., A 2004, 232, 229−237. (14) Fuerstenau, D. W.; Diao, I.; Williams, M. C. Characterization of the wettability of solid particles by film flotation, Part I: Experimental investigation. Colloids Surf. 1991, 60, 127−144. (15) Morvarid, M. K.; Yang, F.; Harbottle, D.; Moran, K.; Masliyah, J.; Xu, Z. Characterizing rag-forming solids. Can. J. Chem. Eng. 2013, 91, 1395−1401. (16) Bhardwaj, A.; Hartland, S. The dynamics of emulsification and demulsification of water-in-crude oil emulsions. Ind. Eng. Chem. Res. 1994, 33 (5), 1271−1279. (17) Byoung, Y. K.; Jun, H. M.; Tae-Hyun, S.; Seung-Man, Y.; JongDuk, K. Demulsification of water-in-crude oil emulsions by a continuous electrostatic dehydrator. Sep. Sci. Technol. 2002, 37 (6), 1307−1320.

4850

DOI: 10.1021/acs.iecr.5b00435 Ind. Eng. Chem. Res. 2015, 54, 4839−4850