Article pubs.acs.org/IECR
Analysis and Characterization of Heat Transfer Fouling during Evaporation of a Lignocellulosic Biomass Process Stream Raghu N. Gurram and Todd J. Menkhaus* †
Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, 501 East St. Joseph Street, Rapid City, South Dakota 57701, United States ABSTRACT: Within a biorefinery production process, concentrating the sugar-rich hydrolysate stream by evaporation prior to fermentation can enhance the fermentation productivity and reduce downstream product recovery costs. However, fouling of the evaporator surface by soluble and suspended solids within the process steams can become problematic. In this study we analyzed fouling characteristics of an acid pretreated pine wood enzymatic hydrolysate using an annular fouling probe in batch mode at 110, 120, 130, and 140 °C with 0, 10, and 20% total suspended solids based on dry weight/volume. Results showed that the rate of fouling and the induction period for onset of fouling depended strongly on temperature, with a maximum fouling resistance of ∼0.5 m2·K/kW experienced at 130 and 140 °C with no suspended solids present. Characterization of the fouling deposits was studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), SEM energy dispersive spectroscopy (SEM-EDS), and inductively coupled plasma (ICP) analysis. CaSO4 was identified as the predominant foulant in the deposits at temperatures >120 °C with 10% total suspended solids. On the basis of the analyses and characterizations, an attempt was made to understand the fouling mechanisms, and fouling reduction techniques were suggested to improve the process efficiencies.
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INTRODUCTION Biorenewable fuels such as ethanol, butanol, biodiesel, and biogasoline have received considerable attention as potential replacements for petroleum-derived products. Recent research and development for producing renewable products has concentrated on utilizing abundant lignocellulosic biomass as opposed to conventional agricultural crop-based raw materials such as cornstarch and sugar cane. Conversion of lignocellulosic biomass into bioethanol involves four main processes: physicochemical pretreatment, enzymatic saccharification, fermentation, and distillation for purification of ethanol.1 Regardless of the microorganisms used during fermentation, the final ethanol concentration depends on the pretreatment and hydrolysis yields.2,3 For milled pine feedstocks, with limited solids loading (≤20%) during the pretreatment, the glucose concentration in the final hydrolysate following enzymatic hydrolysis is only 36−40 g/L even for highly efficient cellulose biochemical conversions of >90%.4−6 This translates into relatively low maximum ethanol titers following fermentation, before distillation, of only 18−20 g/L, even when all of the glucose is converted to ethanol.7−9 This, in turn, leads to elevated energy requirements for purification using distillation, which constitutes more than 50% of the total energy consumption for an entire bioethanol facility.10 Therefore, an imperative improvement needed for cost-effective ethanol production is to obtain higher ethanol yields and higher ethanol concentrations during fermentation.11 One possible solution is to increase the hydrolysate sugar concentrations prior to fermentation. This can reduce distillation energy costs due to elevated titers, while simultaneously enhancing fermentation productivities.12 From preliminary ASPEN Plus simulations (unpublished data), the energy consumption during downstream distillation, with and without the prior evaporation is 1.9 and 8.8 MW, respecitively, to recover 90% ethanol with 95% purity. Using a sugar preconcentration step prior to fermentation, the total energy © 2013 American Chemical Society
consumption including the evaporation is 7.7 MW, which accounts for 12.5% energy savings. Evaporation has been widely used for several decades in the desalination industry to recover purified water and in the food and dairy industry to concentrate fruit juice and milk.13−17 However, fouling of evaporator heat transfer surfaces during evaporation has been identified as a serious problem due to increasing the heat transfer resistance leading to increased energy consumption, higher cleaning costs, and more frequent shut down periods.18 Understanding the mechanisms and tendencies of process materials to foul heat transfer surfaces would provide information to alleviate fouling and increase process energy efficiency. Heat transfer fouling depends on properties of the process streams as well as operating conditions such as temperature and pressure. For instance, it has been shown that the presence of proteins and suspended solids will rapidly foul heat transfer surfaces. In the processing of milk, β-lactoglobulin aggregation was found to be the reason for severe fouling, while small amounts of solid debris, oils, and ash fouled the evaporator heat exchanger in a corn dry-grind thin stillage evaporation process.19−25 On the other hand, a higher temperature gradient (the difference between the process stream and heat transfer surface temperature) has been reported to increase the fouling of Kraft black liquor evaporators, but no mechanistic characterization was completed.26 Similarly, high surface temperatures alone can lead to thermal degradation of sugars.27−29 In addition to fouling, degradation of sugars within lignocellulosic biomass to bioethanol conversion process creates inhibitory products that Received: Revised: Accepted: Published: 11111
April 1, 2013 July 9, 2013 July 19, 2013 July 19, 2013 dx.doi.org/10.1021/ie401038y | Ind. Eng. Chem. Res. 2013, 52, 11111−11121
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Figure 1. (a) Schematic of fouling test unit operated in batch mode. (b) Cross-sectional view of the annular fouling probe.
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MATERIALS AND METHODS Raw Material. Ponderosa pine wood (∼35% moisture) was kindly provided by Baker Timber (Rockerville, SD) in sawdust form. The saw dust was sieved to obtain a dust size of 140 > 120 > 110 °C. This may be due to the fouling at 140 °C taking a different mechanism and thus delaying foulant adherence to the heated surface. The fouling curves with 10% and 20% dry wt/vol TSS followed an asymptotic nature similar to what can be seen during crystallization fouling.19,31 This suggests that there were some salts with inverse solubility that precipitated and fouled the surface by mineral deposition in the presence of solids. Similar observations were reported by Muller-Steinhagen and Branch which showed the precipitation of Burkeite, a salt of sodium carbonate sulfate (Na6CO3(SO4)2) in the fouling deposits of Kraft black liquor evaporators operated at 130 °C
Figure 3. Fouling resistance curves of enzymatic hydrolysate with 0, 10, and 20 wt %/vol TSS at 110 and 120 °C. Error bars represent standard deviation of triplicate samples.
Figure 4. Fouling resistance curves of enzymatic hydrolysate with 0, 10, and 20 wt %/vol TSS at 130 and 140 °C. Error bars represent standard deviation of triplicate samples.
Table 2. Effect of Temperature and Total Suspended Solids on Fouling Resistance, Rate of Fouling, and Rate of Evaporationa temperature (°C) 110
120
130
140
total suspended solids (% TSS)
maximum fouling resistance (m2·K/kW)
average fouling rate (m2·K/kW·s)
average evaporation rate (mL/min)
0 10 20 0 10 20 0 10 20 0 10 20
0.00 0.03 0.16 0.18 0.26 0.29 0.50 0.38 0.20 0.51 0.49 0.30
0.00 0.00 0.12 0.38 1.13 1.26 3.96 2.50 2.15 4.67 5.85 2.99
0.24 0.28 0.19 0.50 1.00 0.90 1.03 1.61 1.48 1.35 2.40 1.80
a
All samples represent the average of three trials with less than 5% deviation between replicates.
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with 65% solids concentration.26 Interestingly, the rates of fouling and evaporation for our study with 10% dry wt/vol TSS are higher compared to 0 and 20% dry wt/vol TSS and reached a maximum 5.85 m2·K/kW·s and 2.40 mL/min at 140 °C, respectively (Table 2). This may also be due to the formation of a thin mineral deposit layer that assisted in faster evaporation and fouling deposition as well. From these observations it can be inferred that formation of a thin mineral deposit layer had improved heat transfer characteristics compared to the protein, sugar, and lignin adsorption observed at 0% and 20% dry wt/vol TSS. The presence of different levels of suspended and soluble solids could also impact boiling point elevation effects and thus cause different intrinsic rates of boiling. While this effect was not specifically isolated, it could have impacted the results observed within this study for different solids levels. According to the study by Larsson et al., the expected boiling point elevation is less than 1 °C based on the amount of solids evaluated in this study.43 At the same time, any boiling point elevation effect would have been similar for samples with the same initial solids present, and all slurries contained the same liquid composed of identical soluble solids. Appearance of Deposits. Deposits obtained from the surface of the fouling probe following all experiments had a smooth appearance and were strongly bonded to the heating surface (Figure 5). In all cases, the deposits had a brownish/black layer of what appeared to be charred sugar and burned lignin immediately adjacent to the heating surface. It was noticed that deposits collected at higher temperatures generally gave highly porous scales (Figure 5F); inferring neucleate boiling might have prevailed where bubbles penetrated the fouled layer. This nucleate deposition mechanism most likely delayed the induction periods observed at 140 than 130 °C (Figures 3 and 4). Jamialahmadi and Muller-Steinhagen reported similar findings of increased nucleation sites and longer induction periods with higher probe heat fluxes in a study to observe the effect of calcium sulfate scale formation under pool boiling conditions.44
Figure 5. Photographs of nonfouled (A) and fouled probe at 120 °C 0% TSS (B), 120 °C 10 wt %/vol TSS (C), 120 °C 20 wt %/vol TSS (D), 130 °C 20 wt %/vol TSS (E), and 140 °C 20 wt %/vol TSS (F).
fingerprint regions 1220−1350 and 2750−3000 cm−1, respectively.45 At the same time, the IR spectra of the concentrate had all the characteristic signals of cellulose, hemicellulose, and its derived polysaccharides.45−47 This indicated that lignin was responsible for forming the first layer of fouling on the heat transfer surface as observed in Figures 3 and 4 with the addition of solids. SEM and SEM-EDS Analysis. Fouling deposits obtained at 120, 130, and 140 °C with 10% dry wt/vol TSS were specifically chosen to determine the effect of temperature through SEM analysis, as the fouling curves indicated a likely crystallization mechanism due to their asymptotic nature with the addition of solids.19,31 Scanning electron micrographs of these deposits are shown in Figure 7A−C. The micrographs show the structure of the deposit on the heat transfer surface. Figure 7A shows a needlelike crystal formation embedded within the lignin material, while Figure 7B and C shows a uniform and regular organized crystalline structure. Such variations in the morphology are a result of the salt precipitation above the solubility limit. The needlelike crystals in Figure 7A show the initiation of salt precipitation with the critical solubility reached at 120 °C, while uniform and more organized crystals in Figure 7 B and C indicate the complete insolubility at higher temperatures 130 and 140 °C. The intensity of sulfur and calcium peaks from the EDS spectra indicate that the crystals formed are predominantly calcium sulfates. Similar SEM calcium sulfate crystal images have been
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FOULING DEPOSIT CHARACTERIZATION FTIR Analysis. FTIR spectra of all the deposits collected at different experimental conditions were very similar to the spectra shown in Figure 6A for the deposits collected at 130 °C with 0, 10 and 20% TSS. The typical functional groups and the IR signal peaks with the possible compounds were referenced from the previous work by Yang et al.45 The deposits collected at different temperatures with 0, 10 and 20% solids loadings consisted of alkenes, esters, aromatics, ketones, and alcohols with oxygencontaining functional groups, e.g., OH stretching (3400−3200 cm−1), CO stretching (1765−1715 cm−1), COC stretching vibration (1270 cm−1), and COH (∼1050 cm−1). However, a significant difference was found in the fingerprint region 1220−1350 and 2750−3000 cm−1 for the fouling deposit IR spectra with no solids (0% TSS), where some peaks were absent. To confirm the additional peaks were due to the presence of solids, fouling deposits obtained at 120, 130, and 140 °C with 20% dry wt/vol TSS were washed to separate the water-soluble components. FTIR spectra of all the washed solids and dried concentrate at different temperatures were very similar to the spectra shown in Figure 6B. Remarkably, the IR spectra of washed solids were very similar to the lignin spectra reported by Yang et al. with the characteristic CO stretching (phenol) and CHn stretching (aromatic compounds) in the highlighted 11117
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were added, uniform and organized crystal formation was notified in the fouling deposit on the heated surface (Figure 7C), which suggested that the crystallization occurred only with the addition of solids. It is thought that sulfate ions from the liquor reacted with a source of calcium, presumably from added solids, to form crystals of CaSO4. However, when more solids were added, the fouling deposit was mostly woody and partly crystalline (Figure 7E), which shows the inhibition of crystal formation by higher solids loadings, thus reducing fouling. Interestingly, this is in agreement with the observed lower rates of fouling and fouling resistance with 20% dry wt/vol TSS than 10% dry wt/vol TSS at 140 °C (Figure 4 and Table 2). ICP and Ash Analysis. ICP analysis was performed to determine elemental composition of the original pine and all of the fouling deposits collected. In the original raw material (Ponderosa pine), calcium was identified as the major component followed by sulfur, potassium, iron, sodium, magnesium, aluminum, phosphorus, and trivial concentrations of manganese, copper, and zinc (Table 3). Sulfur and calcium are the two predominant elements in all the fouling deposits and the concentrations increased as temperature increased ranging from 330 to 700 and 32 to 83 ppt for S and Ca, respectively. Therefore, the observed crystals in SEM images at 120, 130, and 140 °C with addition of 10% (dry wt/vol) solids (Figures 7A−C) were very likely the result of CaSO4 precipitation, with solids as the major source of calcium. However, the concentrations of calcium and sulfur were higher with no solids than 10 and 20% dry wt/vol TSS at any given temperature with no crystallization observed in SEM images (Figure 7D). The higher concentrations may be due to the dissolved calcium during the pretreatment at extreme temperatures. The answer to the question of why there was no precipitation of CaSO4 even though with their higher concentrations can be explained with the presence of aluminum ions in the hydrolysate. A study by Sarig and Mullin and Yehia et al. showed that presence of Al3+ ions inhibited the calcium sulfate precipitation and prolonged the induction period, but when the Al3+ ions were in excess concentrations above 4.2 ppt, an inverse relation was reported.54,55 Interestingly in this study, aluminum had the lowest concentration with 0% TSS at any temperature, which indicated that the presence of aluminum ions inhibited the CaSO4 precipitation, while a rapid sugar and protein deposition rate may not have allowed the crystal structure to develop and organize to the extent observed in Figures 7B and C. On the other hand, fouling deposits obtained with 10% TSS at any temperature had the highest aluminum concentration, which might have catalyzed the CaSO4 precipitation. Zinc had a similar trend, with highest concentration in fouling deposits with 10% dry wt/vol TSS. Results of this study indicate that higher concentrations of zinc may have also catalyzed the CaSO4 crystallization along with elevated aluminum concentrations. Ash content in the deposited fouling layer increased as temperature increased with the maximum of 14.8% dry basis observed at 130 °C with 20% (dry wt/vol) solids added (Table 3). A corresponding increase in Ca, Mg, Mn, and K concentrations in the fouling deposits with increasing temperature were suggestive that these elements are the principle components of ash. As expected, the percentage of ash increased with increase in solids loadings. Proposed Evaporator Fouling Mechanisms. On the basis of the fouling resistance data, SEM, and elemental analysis, it can be summarized that the fouling process strongly depends on temperature and the percentage of total suspended solids. At temperatures above 110 °C without solids, severe fouling with
Figure 6. FTIR absorption spectra of fouling deposits collected at 130 °C with 0, 10, and 20 wt %/vol TSS (A) and washed fouling deposit and the concentrate collected at 130 °C with 20% TSS (B).
reported in previous studies by Hoang et al. and Jamialahmadi and Muller-Steinhagen, who analyzed the effect of temperature on CaSO4 precipitation on heat exchanger surfaces.44,48 CaSO4 has been reported as the predominant foulant in the sugar evaporator scales and water purification heat exchanger scales.32,49−53 Calcium sulfate solubility decreases with increase in temperature, which is consistent with the EDS spectra showing more salt precipitation at higher temperatures.48,52 The form of CaSO4 (an-, hemi-, dihydrate) deposited was not determined. Different predominant fouling compounds were reported in evaporation of different feed materials. For example, Burkerite was identified as the major foulant in the process of Kraft black liquor evaporation, whereas calcium phosphate was found to be most prevalent in the dry-grind maize processing.25,26 These findings show the importance of feed material composition on heat transfer equipment fouling. In all cases, for the pine hydrolysate studied here, EDS spectra have carbon, oxygen, sodium, magnesium, aluminum, silica, phosphorus, and potassium peaks, which would be seen from carbohydrates (sugars) and ash (inorganic remnants of burnt lignin), respectively. SEM images of fouling deposits obtained at 140 °C with 0, 10 and 20% dry wt/vol TSS are shown in Figures 7D, C, and E, respectively. When there were no solids added to the hydrolysate, the fouling deposit was thick and bulky (Figure 7D), which indicated the fouling was due to sugar and protein; however a predominant sulfur peak in the EDS spectra also suggested an abundance of this compound in the hydrolysate. The sulfur was originally introduced during the pretreatment step as sulfuric acid to disrupt the complex structure of lignocellulose. Even after neutralization with ammonium hydroxide prior to enzymatic hydrolysis, the sulfur still existed. When 10% (dry wt/vol) solids 11118
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Figure 7. SEM images (left) and EDS spectra (right) of fouling deposits collected at 120 °C 10 wt %/vol TSS (A), 130 °C 10 wt %/vol TSS (B), 140 °C 10 wt %/vol TSS (C), 140 °C 0% TSS (D), and 140 °C 20 wt %/vol TSS (E).
high resistance was caused by strong adherence of sugars and proteins to the heated surface. When only 10% solids were added, the fouling observed was dominated by crystallization of calcium sulfate with inverse solubility, a precipitation process catalyzed by
the presence of relatively high concentrations of aluminum and zinc ions. The addition of more solids actually resulted in enhancing the evaporation process by inhibiting the dominant protein and crystallization fouling mechanisms. At higher 11119
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Table 3. Elemental Composition (Parts Per Thousand (ppt)) and Ash Content (Percent Dry Basis) of Fouling Deposits Collected at Different Temperatures and Solids Loadings 110 °C Na Mg Al P K S Ca Mn Fe Cu Zn ash
130 °C
120 °C
20% TSS
0% TSS
10% TSS
20% TSS
0% TSS
10% TSS
20% TSS
0% TSS
10% TSS
20% TSS
3.3 2.8 1.5 1.3 5.8 6.9 13.9 0.5 4.9 0.4 0.4 1.6
11.7 5.8 2.0 4.4 19.2 451 35.1 1.4 20.6 1.9 2.0 6.9
11.8 7.6 3.8 3.8 24.0 605 58.5 1.9 21.0 3.4 1.1 9.0
10.6 4.4 5.1 3.0 11.7 414 44.1 1.1 21.5 1.1 2.4 9.8
8.6 5.1 4.8 3.2 9.9 333 33.0 1.2 23.9 0.8 0.8 10.7
7.8 7.1 3.9 4.2 29.4 651 83.7 1.7 20.4 3.9 2.1 8.0
14.8 6.3 5.6 3.8 19.6 540 39.3 1.7 27.5 2.3 3.8 10.5
11.3 6.6 5.4 3.5 16.6 493 33.7 1.5 28.8 0.8 1.2 14.8
12.0 9.4 3.9 4.4 25.3 704 56.4 2.2 23.6 3.5 2.0 5.0
8.1 6.2 6.2 3.8 17.7 487 33.8 1.6 28.7 1.5 3.3 12.6
9.4 6.7 5.2 3.7 16.0 444 32.1 1.5 32.1 1.3 1.3 15.7
(2) Lin, Y.; Tanaka, S. Ethanol Fermentation from Biomass Resources: Current State and Prospects. Appl. Microbiol. Biotechnol. 2006, 69, 627− 642. (3) Groot, W. J.; Sikkenk, C. M.; Waldram, R. H.; van der Lans, R. G. J. M; Luyben, K. C. A. M. Kinetics of Ethanol Production by Baker’s Yeast in an Integratd Process of Fermentation and Microfiltration. Bioprocess Eng. 1992, 8, 39−47. (4) Roche, C. M.; Dibble, C. J.; Stickel, J. J. Laboratory-scale Method for Enzymatic Saccharification of Lignocellulosic Biomass at High-solids Loadings. Biotech. Biofuels. 2009, 2, 28 DOI: 10.1186/1754-6834-2-28. (5) Carter, B.; Squillace, P.; Gilcrease, P. C.; Menkhaus, T. J. Detoxification of a Lingocellulosic Biomass Slurry by Soluble Polyelectrolyte Adsorption for Improved Fermentation Efficiency. Biotechnol. Bioeng. 2011, 108, 2053−60. (6) Martinez, A.; Rodriguez, M. E.; Wells, M. L.; York, S. W.; Preston, J. F.; Ingram, L. O. Detoxification of Dilute Acid Hydrolysates of Lignocellulose with Lime. Biotechnol. Prog. 2001, 17, 287−293. (7) Sassner, P.; Galbe, M.; Zacchi, G. Techno-Economic Evaluation of Bioethanol Production from Three Different Lignocellulosic Materials. Biomass. Bioenergy 2008, 32, 422−430. (8) Galbe, M.; Zachhi, G. A Review of the Production of Ethanol from Softwood. Appl. Microbiol. Biotechnol. 2002, 59, 618−628. (9) Banerjee, S.; Mulidar, S.; Sen, R.; Giri, B.; Satpute, D.; Chakrabarti, T.; Pandey, R. A. Commercializing Lignocellulosic Bioethanol: Technology Bottlenecks and Possible Remedies. Biofuels. Bioproducts. Biorefining 2010, 4, 77−93. (10) Shuler, M. L.; Kargi. F. Bioprocess Engineering: Basic Concepts, 2nd ed.; Prentice Hall: Upper Saddle River, NJ, 2002. (11) Galbe, M.; Sassner, P.; Wingren, A.; Zacchi, G. Process Engineering Economics of Bioethanol Production. Advances. Biochem. Eng. Biotechnol. 2007, 108, 303−327. (12) Dehkhoda, A.; Brandberg, T.; Taherzadeh, M. J. Comparison of Vacuum and High Pressure Evaporated Wood Hydrolyzate for Ethanol Production by Repeated Fed-Batch Using Flocculating. Saccharomyces Cerevisiae. Bioresources 2009, 4, 309−320. (13) El-Dessouky, H. T.; Ettouney, H. M. Multiple-Effect Evaporation Desalination Systems: Thermal Analysis. Desalination 1999, 125, 259− 276. (14) Jaakkola, H. Cost Effective Evaporators for Desalination. Desalination 1997, 108, 357−360. (15) Saravacos, G. D.; Moyer, J. C.; Wooster, G. D. Concentration of Liquid Foods in a Pilot-Scale Falling Film Evaporator. New York’s Food Life Sci. Bull. 1970; No. 4. (16) Heluane, H.; Colombo, M.; Ingaramo, A.; Hernandez, M. R.; Cesca, M. Multipole-Effect Evaporation in a Sugar Factroy. A Measured Varibles Study. Latin. American. Appl. Res. 2001, 31, 519−524. (17) Wright, P. G. Heat Transfer Coefficient Correlations for Robert Juice Evaporators. Int. Sugar. J. 2008, 110, 750−759.
temperatures, a nucleate boiling mechanism prevailed that could have delayed fouling due to increased nucleation sites. With all of these observations, it can be inferred that the mechanism of fouling changes with temperature and addition of solids. Summarizing all the results and mechanisms, fouling can be reduced by enzyme recovery and sulfate ions removal prior to evaporation.
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CONCLUSIONS Fouling characteristics of Ponderosa pine wood hydrolysate were analyzed during concentration process by batch evaporation at 110, 120, 130, and 140 °C with 0, 10 and 20% dry wt/vol total suspended solids through costume designed annular fouling probe. Temperature had a stronger effect on the fouling rates and induction periods; the rate of fouling increased with an increase in initial surface temperature, while the induction periods decreased with temperature. CaSO4 has been identified as the predominant foulant in the deposits through SEM-EDS and ICP elemental analyses. Tentative mechanisms of the deposition process have been proposed and are consistent with the fouling data. Proposed mechanisms suggest that sulfate ion removal and enzyme recovery could be helpful in reducing the cleaning costs by lower fouling to improve the process efficiencies within the lignocellulosic biorefinery industry.
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AUTHOR INFORMATION
Corresponding Author
*Tel.: (605) 394-2422. Fax: (605) 394-1232. E-mail: Todd.
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS Financial support for R.N.G. was provided by the USDA NIFA, AFRI Competitive Grant no. 2010-65504-20372, and the South Dakota School of Mines and Technology. In addition, the work was partially supported by funding from the U.S. Department of Energy, Office of the Biomass Program.
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140 °C
original pine
REFERENCES
(1) Hamelinck, C. N.; van Hooijdonk, G.; Faajj, A. P. C. Ethanol from Lignocellulosic Biomass: Techno-Economic Performance in Short-, Middle- and Long-Term. Biomass. Bioenergy. 2005, 28, 384−410. 11120
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Article
(18) Muller-Steinhagen, H. Heat Transfer Fouling: 50 Years After the Kern and Seaton model. Heat. Transfer. Eng. 2011, 32, 1−13. (19) Fryer, P. J.; Belmar-Beiny, M. T. Fouling of Heat Exchangers in the Food Industry: A Chemical Engineering Perspective. Trends. Food. Sci. Tech. 1991, 2, 33−37. (20) de Jong, P. Impact and Control of Fouling in Milk Processing. Trends. Food. Sci. Tech. 1997, 8, 401−405. (21) Bansal, B.; Chen, X. D. A Critical Review of Milk Fouling in Heat Exchangers. Compr. Rev. Food. Sci. Food. Safety 2006, 5, 27−33. (22) Jebson, R. S.; Chen, H. Performances of Falling Film Evaporators on Whole Milk and a Comparison with Performance on Skim Milk. J. Dairy. Res. 1997, 64, 57−67. (23) Singh, V.; Panchal, C. B.; Eckhoff, S. R. Effect of Corn Oil on Thin Stillage Evaporators. Cereal Chem. 1999, 76, 846−849. (24) Wilkins, M. R.; Singh, V.; Belyea, R. L.; Buriak, P.; Wallig, M. A.; Tumbleson, M. E.; Rausch, K. D. Analysis of Heat Transfer Fouling by Dry-Grind Maize Thin Stillage Using an Annular Fouling Apparatus. Cereal Chem. 2006, 83, 121−126. (25) Wilkins, M. R.; Singh, V.; Belyea, R. L.; Buriak, P.; Wallig, M. A.; Tumbleson, M. E.; Rausch, K. D. Effect of pH on Fouling Characteristics and Deposit Compositions in Dry-Grind Thin Stillage. Cereal Chem. 2006, 83, 311−314. (26) Muller-Steinhagen, H.; Branch, C. A. Heat Transfer Fouling in Kraft Black Liquor Evaporators. Exp. Ther. Flu. Sci. 1997, 14, 425−437. (27) Sugisawa, H. The Thermal Degradation of Sugars. II. The Volatile Decomposition Products of Glucose Caramel. J. Food. Sci 1966, 31, 381−385. (28) Fagerson, I. S. Thermal Degradation of Carbohydrates: A Review. J. Agri. Food. Chem. 1969, 17, 747−750. (29) Nolasco, J., Jr.; Massaguer, P. R. Thermal Degradation Kinetics of Sucrose, Glucose and Fructose in Sugarcane Must for Bioethanol Production. J. Food. Process. Eng. 2006, 29, 462−477. (30) Bott, T. R. Fouling Notebook; The Institution of Chemical Engineers: Rugby, England, 1990. (31) Mwaba, M. G.; Golriz, M. R.; Gu, J. A Semi-Empirical Correlation for Crystallization Fouling on Heat Exchange Surfaces. Appl. Thermal. Eng. 2006, 26, 440−447. (32) East, C. P.; Doherty, W. O. S; Fellows, C. M.; Yu, H. Characterization of Sugar Juice Heat Exchanger Tube Deposit. Surf. Interface Anal. 2011, 43, 1231−1239. (33) Yu, H.; Sheikholeslami, R. Composite Fouling on Heat Exchange Surface in Australian Sugar Mill Evaporator. Heat. Transfer. Eng. 2009, 30, 1033−1040. (34) Gurram, R. N; Datta, S.; Lin, Y. J.; Snyder, S. W.; Menkhaus, T. J. Removal of Enzymatic and Fermentation Inhibitory compounds from Biomass Slurries for Enhanced Biorefinery Process Efficiencies. Bioresour. Technol. 2011, 102, 7850−7859. (35) Burke, D. R.; Anderson, J.; Gilcrease, P. C.; Menkhuas, T. J. Enhanced Solid−Liquid Clarification of Lignocellulosic Slurries Using Polyelectrolyte Flocculating Agents. Biomass. Bioenergy 2011, 35, 391− 401. (36) Arora, A.; Dien, B. S.; Belyea, R. L.; Singh, V.; Tumbleson, M. E.; Rausch, K. D. Heat Transfer Fouling Characteristics of Microfiltered Thin Stillage from the Dry Grind Process. Bioresour. Technol. 2010, 101, 6521−6527. (37) Palmqvist, E.; Grage, H.; Meinander, N. Q.; Hahn-Hagerdal, B. Main and Interaction Effects of Acetic Acid, Furfural, and phydroxybenzoic Acid on Growth and Ethanol Productivity of Yeasts. Biotechnol. Bioeng. 1999, 63, 46−55. (38) Carter, B.; Gilcrease, P. C.; Menkhaus, T. J. Removal and Recovery of Furfural, 5-hydroxymethylfurfural and Acetic Acid from Aqueous Solutions Using a Soluble Polyelectrolyte. Biotechnol. Bioeng. 2011b, 108, 2046−52. (39) Moulin, G.; Boze, H.; Galzy, P. Inhibition of Alcoholic Fermentation. Biotech. Genetic. Eng. Rev. 1984, 2, 365−382. (40) Yang, B.; Gray, M. C.; Liu, C.; Lloyd, T. A.; Stubler, S. L.; Converse, A. O.; Wyman, C. E. Unconventional Relationships for Hemicellulose Hydrolysis and Subsequent Cellulose Digestion. Lignocellulose Biodegradation; Saha, B.C., Hayashi, K., Eds.; ACS
Symposium Series 889; American Chemical Society: Washington, D.C., 2004; Chapter 6, pp 100−125. (41) Yang, B.; Wyman, C. E. Dilute Acid and Autohydrolysis Pretreatment. In Methods in Molecular Biology: Biofuels; Mielenz, J., Ed.; Humana Press: Totowa, NJ, 2009. (42) Agbisit, R. M.; Singh, V.; Valenti, J. J.; Kakleas, M.; Tumbleson, M. E.; Rausch, K. D. Technique to Measure Surface-Fouling Tendencies of Steepwater from Corn Wet Milling. Cereal Chem. 2003, 80, 84−86. (43) Larsson, M.; Galbe, M.; Zacchi, G. Recirculation of Process Water in the Prodcution of Ethanol from Softwood. Bioresour. Technol. 1997, 60, 143−151. (44) Jamialahmadi, M.; Muller-Steinhagen, H. A New Model for the Effect of Calcium Sulfate Scale Formation on Pool Boiling Heat Transfer. J. Heat Transfer 2004, 126, 507−517. (45) Yang, H.; Yan, R.; Chen, H.; Lee, D. H.; Zheng, C. Characteristics of Hemicellulose, Cellulose and Lignin Pyrolysis. Fuel 2007, 86, 1781− 1788. (46) Higgins, H. G.; Stewart, C. M.; Harrington, K. J. Infrared Spectra of Cellulose and Related Polysaccharides. J. Polym. Sci. 1961, 51, 59−84. (47) Ibrahim, M.; Alaam, M.; El-Heas, H.; Jalbout, A. F.; de Leon, A. Analysis of Structure and Vibrational Spectra of Glucose and Fructose. Ecl. Quim. 2006, 31, 15−20. (48) Hoang, T. A.; Ang, H. M.; Rohl, A. L. Effects of Temperature on the Scaling of Calcium Sulphate in Pipes. Powder. Tech. 2007, 179, 31− 37. (49) Sheikholeslami, R.; Ng, M. Calcium Sulfate Precipitation in Presence of Non-domimant Calcium Carbonate: Thermodynamics and Kinetics. Ind. Eng. Chem. Res. 2001, 40, 3570−3578. (50) Broadfoot, R.; Tan, S. Y. Understanding juice flow patterns in Robert evaporators. Aus. Soc. Sugar. Cane. Technol. 2005, 27, 400. (51) Lu, C. H.; Fabuss, B. M. Calcium Sulfate Scaling in Saline Water Distillation. Ind. Eng. Chem. Proc. Des. Dev. 1968, 7, 206−212. (52) Hasson, D.; Zahavi, J. Mechanism of Calcium Sulfate Scale Deposition on Heat Transfer Surfaces. Ind. Eng. Chem. Fund. 1970, 9, 1− 10. (53) Glater, J.; Schwartz, J. High-Temperature Solubility of Calcium Sulfate Hemihydrate and Anhydrite in Natural Seawater Concentrates. J. Chem. Eng. Data 1976, 21, 47−52. (54) Sarig, S.; Mullin, J. W. Effect of Trace Impurities on Calcium Sulphate Precipitation. J. Chem. Tech. Biotech. 1982, 32, 525−531. (55) Yehia, N. S.; Ali, M. M.; Kandil, K. M.; El-Maadawy, M. M. Effects of Some Parameters Affecting the Crystallization Rate of Calcium Sulfate Dihydrate in Sodium Chloride. Solution J. Am. Sci. 2011, 7, 635− 644.
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