- Email: [email protected]
Product distribution and heating performance of lignocellulosic biomass pyrolysis using microwave heating
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ScienceDirect ScienceDirect Energy Procedia 00 (2018) 000–000 ScienceDirect ScienceDirect Energy Procedia 00 (2018) 000–000
Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available
Energy (2018) 000–000 910–915 EnergyProcedia Procedia152 00 (2017)
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Applied Energy Symposium and Forum 2018: Low carbon cities and urban energy systems, Applied Energy Symposium andSymposium Forum 2018: carbon cities and urbancities energy CUE2018, 5–7 June 2018, Shanghai, China CUE2018-Applied Energy andLow Forum 2018: Low carbon andsystems, CUE2018, 5–7 June 2018, Shanghai, China urban energy systems, 5–7 June 2018, Shanghai, China
Product distribution and heating performance of lignocellulosic Product distribution and heating performance ofand lignocellulosic The 15th International Symposium District Heating Cooling biomass pyrolysis using on microwave heating biomass pyrolysis using microwave heating a Assessing the feasibility of aausing theKuan heatbb, Shang-Lien demand-outdoor Yu-Fong Huang , Pei-Te Chiueh , Wen-Hui Loa,a,* a Yu-Fong Huang , Pei-Te Chiueh , Wen-Hui Kuan , Shang-Lien Lo * temperature functionEngineering, for aNational long-term district forecast Graduate Institute of Environmental Taiwan University, 1 Rooseveltheat Rd. Sec. demand 4, Taipei 106, Taiwan, ROC a
b
a Department of Safety, Health and Environmental Engineering, Ming Chi University Gongjuan New TaipeiROC City 243, Graduate Institute of Environmental Engineering, National Taiwan University,of 1 Technology, Roosevelt Rd.84 Sec. 4, TaipeiRd., 106, Taiwan, b a,b,c and Environmental a c Rd., New Taipei City c 243, ROC Department of Safety, Health Engineering,aTaiwan, Ming Chi Universitybof Technology, 84 Gongjuan Taiwan, ROC
I. Andrić
*, A. Pina , P. Ferrão , J. Fournier ., B. Lacarrière , O. Le Corre
a
IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France Abstract c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France
Abstract Lignocellulosic biomass feedstocks, including rice straw, rice husk, corn stover, sugarcane bagasse, sugarcane peel, waste coffee Lignocellulosic biomass riceleucaena straw, rice husk, cornpyrolyzed stover, sugarcane sugarcane peel, waste coffee grounds, bamboo leaves,feedstocks, pennisetumincluding grass, and wood, were by usingbagasse, microwave heating. Both maximum grounds, leaves,rate pennisetum grass,pyrolysis and leucaena wood, werebiomass pyrolyzed by using microwave Bothpower maximum temperature and heating of microwave of lignocellulosic increased with increasingheating. microwave level. Abstractbamboo temperature andrequired heating rate of microwave of lignocellulosic biomass increasing level. The minimum microwave powerpyrolysis level could be approximately 60 increased W. Solid,with liquid, and gasmicrowave yields of power microwave The minimum power level could approximately 60 W.theSolid, liquid, andsolutions gas yields ofdecreasing microwave pyrolysis at 500required W weremicrowave inare thecommonly ranges of addressed 16–22, 40–48, 30–40 wt%, respectively. gaseous products primarily District heating networks in be theand literature as one of mostThe effective forwere the pyrolysis atof500 WCH were infrom the ranges 16–22, 40–48, 30–40 respectively. Thewhich gaseous products were primarily andthe CO whose concentration wererequire inwt%, thehigh ranges of 18–25, 6–8,are 51–59, andthrough 10–14 vol%, composed H2,emissions greenhouse gas building sector. These and systems investments returned the heat 4, CO, 2, of CH and COconditions whose concentration werevol%. in the rangesmicrowave of 18–25, 6–8, and 10–14decrease, vol%, composed Hthe respectively. The of light only 3–5 Besides, pyrolysis becould more energy2,concentration 4, CO, climate 2,hydrocarbons sales. Dueofto changed and was building renovation policies, heat demand in 51–59, theshould future respectively. Theinvestment concentration of period. light hydrocarbons was only 3–5 vol%. Besides, microwave pyrolysis should be more energysaving than conventional pyrolysis because of higher devolatilization and lower reaction temperature required. prolonging the return saving thanscope conventional pyrolysis of feasibility higher devolatilization and lower reaction temperature required. The main of this paper is to because assess the of using the heat demand – outdoor temperature function for heat demand Copyright 2018 Elsevier Ltd. All rights reserved. forecast. © The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 Copyright © © 2018 2018 Elsevier Elsevier Ltd. Ltd. All rights reserved. Copyright All rights reserved. Selection under responsibility of the scientific committee of Applied Energy Symposium and 2018:district Low buildingsand thatpeer-review vary in both construction period weather scenarios (low, medium, high)Forum and three Selection and peer-review under responsibility ofand thetypology. scientificThree committee of the CUE2018-Applied Energy Symposium and Selection andscenarios peer-review under responsibility of the scientific committee of Applied Energy Symposium anddemand Forum values 2018: Low carbon cities and urban energy systems, CUE2018. renovation were developed (shallow, intermediate, deep). To estimate the error, obtained heat were Forum 2018: Low carbon cities and urban energy systems. carbon citieswith andresults urban energy systems, heat CUE2018. compared from a dynamic demand model, previously developed and validated by the authors. Keywords: Lignocellulosic Pyrolysis; Microwave The results showed thatbiomass; when only weather changeheating is considered, the margin of error could be acceptable for some applications Keywords: biomass; Pyrolysis; Microwave heating (the errorLignocellulosic in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). 1.The Introduction value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the 1.decrease Introduction in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation considered). Onhigh the other hand,tofunction intercept increased for 7.8-12.7% decade (depending the Biomassscenarios is a resource showing potential deal with challenges of sustainable andper green energy, and itsonuse coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and Biomass is a resource showing high potential to deal with challenges of sustainable and green energy, and its use is expected to grow and expand in the near future [1]. Biomass feedstocks that can be produced with much lower improve thegreenhouse-gas accuracy demand is expected to grow of andheat expand inestimations. thethan neartraditional future [1]. fossil Biomass feedstocks can or be no produced with much life-cycle emissions fuels and withthatlittle competition with lower food
life-cycle emissions thangrown traditional fossil lands fuels abandoned and with little or no competition food productiongreenhouse-gas may include: perennial plants on degraded from agricultural use, cropwith residues, © 2017 Themay Authors. Published by Elsevier production include: perennial plantsLtd. grown on degraded lands abandoned from agricultural use, crop residues, Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. Tel.: +886-2-2362-5373; fax: +886-2-2392-8821. Keywords: Heat demand; Forecast; Climate change E-mail address:author. [email protected] * Corresponding Tel.: +886-2-2362-5373; fax: +886-2-2392-8821. E-mail address: [email protected]
1876-6102 Copyright © 2018 Elsevier Ltd. All rights reserved. Selection peer-review under responsibility the scientific 1876-6102and Copyright © 2018 Elsevier Ltd. All of rights reserved. committee of the Applied Energy Symposium and Forum 2018: Low carbon cities and urban energy systems, CUE2018. Selection and peer-review under responsibility of the scientific committee of the Applied Energy Symposium and 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Forum 2018: Low carbon cities urbanCommittee energy systems, Peer-review under responsibility of theand Scientific of The 15thCUE2018. International Symposium on District Heating and Cooling.
1876-6102 Copyright © 2018 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the CUE2018-Applied Energy Symposium and Forum 2018: Low carbon cities and urban energy systems. 10.1016/j.egypro.2018.09.092
2
Yu-Fong Huang et al. / Energy Procedia 152 (2018) 910–915 Author name / Energy Procedia 00 (2018) 000–000
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sustainably harvested wood and forest residues, double crops and mixed cropping systems, and municipal and industrial wastes [2]. In most cases, biomass is converted into fuels and chemicals by using biochemical and thermochemical processes. However, it is difficult to process the biomass biologically because of the natural resistance of plant cell walls to microbial and enzymatic deconstruction, collectively known as biomass recalcitrance [3]. Biomass can be used in a variety of thermochemical ways to provide energy: direct combustion to produce heat, gasification to produce gaseous fuels, and fast pyrolysis to produce liquid fuels [4]. The products of these thermochemical processes are divided into a volatile fraction consisting of gases, vapors and tar components, and a carbon-rich solid residue [5]. Microwaves are a portion of electromagnetic spectrum with wavelengths from 1 mm to 1 m, corresponding to frequencies between 300 MHz and 300 GHz [6–11]. Microwave heating is unique and offers a number of advantages over conventional heating processes, such as rapid and selective heating, quick start-up and stopping, and higher level of safety and automation [6]. Microwave heating is the transfer of electromagnetic energy to thermal energy and thus is energy conversion, rather than heat transfer [7], so there could be less or even negligible limitation caused by heat transfer in microwave processing. Microwave heating techniques are currently undergoing investigation for applications in various fields where the advantages of microwave radiation may lead to substantial savings in energy consumption, processing time, and environmental remediation [9]. A number of potential problems are inherent in microwave heating, including the phenomenon of hotspot formation [11]. Biomass pyrolysis assisted by microwave heating is a promising technique for the production of biofuels and chemicals [11– 17]. The most important advantage of microwave pyrolysis is the significant reduction in temperature (and thus savings in energy) observed for microwave pyrolysis compared with conventional pyrolysis, particularly for gas production [13]. A preliminary study of microwave pyrolysis has been presented in the previous article [18]. In this study, both product distribution and heating performance of microwave pyrolysis of various lignocellulosic biomass feedstocks were analyzed and discussed in depth. Besides, the solid yield of microwave pyrolysis of lignocellulosic biomass was compared with that of conventional pyrolysis. 2. Materials and methods 2.1. Materials The samples of this study were nine different lignocellulosic biomass feedstocks, such as rice straw (RS), rice husk (RH), corn stover (CS), sugarcane bagasse (SB), sugarcane peel (SP), coffee grounds (CG), bamboo leaves (BL), pennisetum grass (PG), and leucaena wood (LW), which were collected locally from factories, markets and farms. All the biomass feedstocks were naturally air-dried, shredded, and sieved by a 50-mesh (0.297 mm) screen prior to microwave pyrolysis and related characterization experiments. 2.2. Experimental device This study used a single-mode (focused) microwave device which operates at a frequency of 2.45 GHz. A schematic diagram of microwave pyrolysis system can be found elsewhere [19]. Both reaction tube (40 cm length, 5 cm outer diameter) and crucible (3 cm height, 4 cm outer diameter) were made of quartz. A K-type thermocouple sensor was placed against the bottom of the quartz crucible to measure the real-time temperature of biomass sample. Pure nitrogen gas was purged into the system at a flow rate of 50 mL/min to ensure anoxic condition in the reaction system. During the microwave pyrolysis experiments, reflected microwave power levels were lowered by adjusting a three-stub tuner and a short-circuit plunger. 2.3. Experimental procedure The shredded and sieved biomass feedstock (3–5 g) was added to the quartz crucible and then placed inside the quartz tube. The height of the quartz crucible was adjusted to be located in the path of microwave propagation. After sufficient purging was performed to maintain an inert atmosphere, the power supply was turned on and the microwave output was switched to a designated microwave power level (300, 400, and 500 W) for a designated
Yu-Fong Huang et al. / Energy Procedia 152 (2018) 910–915 Author name / Energy Procedia 00 (2018) 000–000
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3
processing time (30 min). The actual working microwave power level was determined by the incident power level subtracting the reflected power level. After the designated processing time, the power supply was turned off, and the carrier gas purging was stopped. The vapor produced during the experiment immediately passed through a condenser tube. The condensable and non-condensable parts of the product vapor were regarded as liquid and gaseous product, respectively. After self-cooled down to room temperature, the solid residue remaining in the quartz crucible was removed, weighed, and then stored in a desiccator. 3. Results and discussion 3.1. Biomass characteristics The general characteristics of lignocellulosic feedstocks are listed in Table 1. The combustible contents (volatile matter plus fixed carbon) of CS, SB, SP, and LW were relatively high (95–98 wt%), whereas those of RH and BL were lower (88–89 wt%). The carbohydrate content (hemicellulose plus cellulose) of SB was highest (approximately 74 wt%), whereas those of RH and BL were lowest (58–60 wt%). LW had the highest HHV (19.27 MJ/kg) whereas BL had the lowest (15.75 MJ/kg). According to the characteristics, CS, SB, SP, PG, and LW could have higher bioenergy potential, whereas the potential of RH and BL seems to be relatively low. Table 1. General characteristics of the lignocellulosic feedstocks. RS
RH
CS
SB
SP
CG
BL
PG
LW
9.32
6.34
8.58
8.61
5.30
7.97
7.14
8.32
10.50
Volatile matter
79.22
80.45
82.58
86.02
80.04
78.69
71.59
88.30
78.80
Fixed carbon
12.27
8.70
12.48
9.93
15.42
14.25
16.57
6.17
18.72
8.51
10.85
4.94
4.05
4.54
7.06
11.84
5.53
2.48
45.76
43.98
49.38
48.88
46.47
44.89
39.98
46.57
47.93
Moisture (wt%) Proximate analysis (wt%) a
Ash Ultimate analysis (wt%)
b
Carbon Hydrogen
6.22
5.94
6.52
6.71
6.23
6.14
5.81
6.27
6.59
Oxygenc
47.50
49.68
43.47
44.15
46.38
48.62
53.09
46.94
38.27
Nitrogen
0.52
0.40
0.63
0.27
0.92
0.35
1.12
0.22
7.21
Lignocellulosic analysis (wt%)b Extractives
4.39
5.52
5.27
5.44
8.18
12.35
5.28
5.18
7.53
Hemicellulose
31.12
28.03
28.94
27.40
26.40
30.03
25.55
29.07
26.56
Cellulose
38.14
30.42
43.97
46.55
41.11
33.10
34.14
35.52
37.36
Lignin
26.35
36.02
21.82
20.61
24.31
24.52
35.03
30.23
28.55
HHV (MJ/kg)
16.16
15.91
17.06
16.92
17.03
16.78
15.75
16.82
19.27
a
Dry basis. b Dry and ash-free basis. c Calculated by difference.
3.2. Microwave heating The maximum temperatures and heating rates of microwave pyrolysis of the nine biomass feedstocks at different microwave power levels are illustrated in Fig. 1. Both maximum temperature and heating rate increased with increasing microwave power level. Among these biomass feedstocks, the maximum temperatures of SP and BL were generally highest and lowest, respectively. Once again, the heating rates of SP and BL were generally highest and lowest, respectively. In general, the performance of microwave heating was positively correlated with the contents of volatile matter, cellulose, and carbon, but negatively correlated with the contents of ash, lignin, and
4
Yu-Fong Huang et al. / Energy Procedia 152 (2018) 910–915 Author name / Energy Procedia 00 (2018) 000–000
913
oxygen. The composition of biomass could therefore have substantial effect on microwave heating, although the effect should be weaker than that of microwave power level.
Fig. 1. Maximum temperatures and heating rates of microwave pyrolysis at different microwave power levels.
A linear relationship between heating rate and microwave power level (R2 = 0.98) can be found by using the regression analysis:
HR 0.23MPL 14.33
(1)
where HR is the heating rate and MPL is the microwave power level. If HR is 0, MPL will be approximately 62 W that could be regarded as the minimum required microwave power level to initiate the microwave heating of lignocellulosic biomass. On the other hand, there was a logarithmic relationship between maximum temperature and microwave power level (R2 = 0.99): MT 231.88 ln( MPL) 924.48
(2)
where MT is the maximum temperature. When MT is assumed to be the room temperature (25 ºC), MPL will be approximately 60 W that could be regarded as the minimum required microwave power level to initiate the microwave heating of lignocellulosic biomass as well. The two MPL values are not so different, and their difference should be attributable to the uncertainty of temperature measurement or other experimental errors. 3.3. Product yield The three-phase product distributions of microwave pyrolysis of the lignocellulosic biomass feedstocks at a microwave power level of 500 W are illustrated in Fig. 2. Among these feedstocks, their gas yields ranged from 30
914
Yu-Fong Huang et al. / Energy Procedia 152 (2018) 910–915 Author name / Energy Procedia 00 (2018) 000–000
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wt% to 40 wt%, the liquid yields were in the range from 40 wt% to 48 wt%, and the solid yields were in the range from 16 wt% to 22 wt%. SB and CS had the highest gas yield, whereas RH had the lowest. On the contrary, RH had the highest liquid yield, whereas CS had the lowest.
Fig. 2. Three-phase product distributions of lignocellulosic biomass pyrolysis at a microwave power level of 500 W.
The concentrations of H2, CH4, CO, and CO2 were in the ranges of 18–25, 6–8, 51–59, and 10–14 vol%, respectively. Among these lignocellulosic biomass feedstocks, microwave pyrolysis of RS and RH produced more H2 whereas BL produced less. However, microwave pyrolysis of SP and BL produced more CO but RS, RH, and CG produced less. This could be attributable to their different elemental and lignocellulosic compositions, resulting in different microwave heating performance and reaction intensity. Besides, the formation and type of primary product (prior to secondary reactions) could be another crucial factor that needs to be further testified and verified. A comparison in solid yields of microwave pyrolysis and conventional pyrolysis of rice straw at various temperatures is illustrated in Fig. 3. As can be seen, the solid yield of microwave pyrolysis was substantially lower than that of conventional pyrolysis when both methods were carried out at the same temperature. This difference was up to approximately 30 wt% at the temperatures of 200–250 ºC, and it decreased to approximately 5 wt% at the temperatures of 300–500 ºC. Furthermore, the solid yield of microwave pyrolysis at approximately 500 ºC almost equals to the sum of fixed carbon and ash contents of rice straw, and thus the fixed carbon fraction of rice straw would start to be pyrolyzed at higher temperatures. However, conventional pyrolysis would need approximately 600 ºC for the pyrolysis of fixed carbon. In general, to achieve the same solid yield, the temperature required for conventional pyrolysis would be higher than that for microwave pyrolysis by approximately 100 ºC. Therefore, compared with conventional pyrolysis, microwave pyrolysis should be more energy-saving.
Fig. 3. A comparison in solid yields of microwave pyrolysis and conventional pyrolysis of rice straw.
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4. Conclusions The maximum temperature and heating rate of microwave pyrolysis of lignocellulosic biomass both increased with increasing microwave power level. The minimum required microwave power level could be approximately 60 W, which was determined according to the correlations of microwave power level with maximum temperature and heating rate. The difference in gaseous product compositions could be attributable to different elemental and lignocellulosic compositions, resulting in different microwave heating performance and reaction intensity. To achieve the same solid yield, the temperature required for conventional pyrolysis would be higher than that for microwave pyrolysis by approximately 100 °C. Microwave pyrolysis should be more energy-saving than conventional pyrolysis because of lower solid yield (i.e., higher devolatilization extent) and lower reaction temperature required. Acknowledgements The authors gratefully acknowledge the financial support from the Ministry of Science and Technology, Taiwan, ROC (104-2221-E-002-029-MY3). References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19]
Melero JA, Iglesias J, Garcia A. Biomass as renewable feedstock in standard refinery units. Feasibility, opportunities and challenges. Energy Environ Sci 2012;5:7393–420. Tilman D, Socolow R, Foley JA, Hill J, Larson E, Lynd L, et al. Beneficial biofuels—the food, energy, and environment trilemma. Science 2009;325:270–1. Himmel ME, Ding SY, Johnson DK, Adney WS, Nimlos MR, Brady JW, et al. Biomass recalcitrance: engineering plants and enzymes for biofuels production. Science 2007;315:804–7. Bridgwater AV, Meier D, Radlein D. An overview of fast pyrolysis of biomass. Org Geochem 1999;30:1479–93. Yaman S. Pyrolysis of biomass to produce fuels and chemical feedstocks. Energy Conv Manag 2004;45:651–71. Haque KE. Microwave energy for mineral treatment processes—a brief review. Int J Miner Process 1999;57:1–24. Thostenson ET, Chou TW. Microwave processing: fundamentals and applications. Compos Pt A-Appl Sci Manuf 1999;30:1055–71. Lidström P, Tierney J, Wathey B, Westman J. Microwave assisted organic synthesis—a review. Tetrahedron 2001;57:9225–83. Jones DA, Lelyveld TP, Mavrofidis SD, Kingman SW, Miles NJ. Microwave heating applications in environmental engineering—a review. Resour Conserv Recycl 2002;34:75–90. Kappe CO. Controlled microwave heating in modern organic synthesis. Angew Chem Int Ed 2004;43:6250–84. Appleton TJ, Colder RI, Kingman SW, Lowndes IS, Read AG. Microwave technology for energy-efficient processing of waste. Appl Energy 2005;81:85–113. Menéndez JA, Arenillas A, Fidalgo B, Fernandez Y, Zubizarreta L, Calvo EG, et al. Microwave heating processes involving carbon materials. Fuel Process Technol 2010;91:1–8. Luque R, Menéndez JA, Arenillas A, Cot J. Microwave-assisted pyrolysis of biomass feedstocks: the way forward? Energy Environ Sci 2012;5:5481–8. Lam SS, Chase HA. A review on waste to energy processes using microwave pyrolysis. Energies 2012;5:4209–32. Yin C. Microwave-assisted pyrolysis of biomass for liquid biofuels production. Bioresour Technol 2012;120:273–84. Mushtaq F, Mat R, Ani FN. A review on microwave assisted pyrolysis of coal and biomass for fuel production. Renew Sust Energ Rev 2014;39:555–74. Li J, Dai J, Liu G, Zhang H, Gao Z, Fu J, et al. Biochar from microwave pyrolysis of biomass: A review. Biomass Bioenerg 2016 ;94:228– 44. Lo SL, Huang YF , Chiueh PT , Kuan WH. Microwave pyrolysis of lignocellulosic biomass. Energy Procedia 2017;105:41–6. Huang YF , Chiueh PT , Kuan WH , Lo SL. Effects of lignocellulosic composition and microwave power level on the gaseous product of microwave pyrolysis. Energy 2015;89:974–81.
ScienceDirect ScienceDirect Energy Procedia 00 (2018) 000–000 ScienceDirect ScienceDirect Energy Procedia 00 (2018) 000–000
Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available
Energy (2018) 000–000 910–915 EnergyProcedia Procedia152 00 (2017)
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
www.elsevier.com/locate/procedia
Applied Energy Symposium and Forum 2018: Low carbon cities and urban energy systems, Applied Energy Symposium andSymposium Forum 2018: carbon cities and urbancities energy CUE2018, 5–7 June 2018, Shanghai, China CUE2018-Applied Energy andLow Forum 2018: Low carbon andsystems, CUE2018, 5–7 June 2018, Shanghai, China urban energy systems, 5–7 June 2018, Shanghai, China
Product distribution and heating performance of lignocellulosic Product distribution and heating performance ofand lignocellulosic The 15th International Symposium District Heating Cooling biomass pyrolysis using on microwave heating biomass pyrolysis using microwave heating a Assessing the feasibility of aausing theKuan heatbb, Shang-Lien demand-outdoor Yu-Fong Huang , Pei-Te Chiueh , Wen-Hui Loa,a,* a Yu-Fong Huang , Pei-Te Chiueh , Wen-Hui Kuan , Shang-Lien Lo * temperature functionEngineering, for aNational long-term district forecast Graduate Institute of Environmental Taiwan University, 1 Rooseveltheat Rd. Sec. demand 4, Taipei 106, Taiwan, ROC a
b
a Department of Safety, Health and Environmental Engineering, Ming Chi University Gongjuan New TaipeiROC City 243, Graduate Institute of Environmental Engineering, National Taiwan University,of 1 Technology, Roosevelt Rd.84 Sec. 4, TaipeiRd., 106, Taiwan, b a,b,c and Environmental a c Rd., New Taipei City c 243, ROC Department of Safety, Health Engineering,aTaiwan, Ming Chi Universitybof Technology, 84 Gongjuan Taiwan, ROC
I. Andrić
*, A. Pina , P. Ferrão , J. Fournier ., B. Lacarrière , O. Le Corre
a
IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France Abstract c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France
Abstract Lignocellulosic biomass feedstocks, including rice straw, rice husk, corn stover, sugarcane bagasse, sugarcane peel, waste coffee Lignocellulosic biomass riceleucaena straw, rice husk, cornpyrolyzed stover, sugarcane sugarcane peel, waste coffee grounds, bamboo leaves,feedstocks, pennisetumincluding grass, and wood, were by usingbagasse, microwave heating. Both maximum grounds, leaves,rate pennisetum grass,pyrolysis and leucaena wood, werebiomass pyrolyzed by using microwave Bothpower maximum temperature and heating of microwave of lignocellulosic increased with increasingheating. microwave level. Abstractbamboo temperature andrequired heating rate of microwave of lignocellulosic biomass increasing level. The minimum microwave powerpyrolysis level could be approximately 60 increased W. Solid,with liquid, and gasmicrowave yields of power microwave The minimum power level could approximately 60 W.theSolid, liquid, andsolutions gas yields ofdecreasing microwave pyrolysis at 500required W weremicrowave inare thecommonly ranges of addressed 16–22, 40–48, 30–40 wt%, respectively. gaseous products primarily District heating networks in be theand literature as one of mostThe effective forwere the pyrolysis atof500 WCH were infrom the ranges 16–22, 40–48, 30–40 respectively. Thewhich gaseous products were primarily andthe CO whose concentration wererequire inwt%, thehigh ranges of 18–25, 6–8,are 51–59, andthrough 10–14 vol%, composed H2,emissions greenhouse gas building sector. These and systems investments returned the heat 4, CO, 2, of CH and COconditions whose concentration werevol%. in the rangesmicrowave of 18–25, 6–8, and 10–14decrease, vol%, composed Hthe respectively. The of light only 3–5 Besides, pyrolysis becould more energy2,concentration 4, CO, climate 2,hydrocarbons sales. Dueofto changed and was building renovation policies, heat demand in 51–59, theshould future respectively. Theinvestment concentration of period. light hydrocarbons was only 3–5 vol%. Besides, microwave pyrolysis should be more energysaving than conventional pyrolysis because of higher devolatilization and lower reaction temperature required. prolonging the return saving thanscope conventional pyrolysis of feasibility higher devolatilization and lower reaction temperature required. The main of this paper is to because assess the of using the heat demand – outdoor temperature function for heat demand Copyright 2018 Elsevier Ltd. All rights reserved. forecast. © The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 Copyright © © 2018 2018 Elsevier Elsevier Ltd. Ltd. All rights reserved. Copyright All rights reserved. Selection under responsibility of the scientific committee of Applied Energy Symposium and 2018:district Low buildingsand thatpeer-review vary in both construction period weather scenarios (low, medium, high)Forum and three Selection and peer-review under responsibility ofand thetypology. scientificThree committee of the CUE2018-Applied Energy Symposium and Selection andscenarios peer-review under responsibility of the scientific committee of Applied Energy Symposium anddemand Forum values 2018: Low carbon cities and urban energy systems, CUE2018. renovation were developed (shallow, intermediate, deep). To estimate the error, obtained heat were Forum 2018: Low carbon cities and urban energy systems. carbon citieswith andresults urban energy systems, heat CUE2018. compared from a dynamic demand model, previously developed and validated by the authors. Keywords: Lignocellulosic Pyrolysis; Microwave The results showed thatbiomass; when only weather changeheating is considered, the margin of error could be acceptable for some applications Keywords: biomass; Pyrolysis; Microwave heating (the errorLignocellulosic in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). 1.The Introduction value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the 1.decrease Introduction in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation considered). Onhigh the other hand,tofunction intercept increased for 7.8-12.7% decade (depending the Biomassscenarios is a resource showing potential deal with challenges of sustainable andper green energy, and itsonuse coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and Biomass is a resource showing high potential to deal with challenges of sustainable and green energy, and its use is expected to grow and expand in the near future [1]. Biomass feedstocks that can be produced with much lower improve thegreenhouse-gas accuracy demand is expected to grow of andheat expand inestimations. thethan neartraditional future [1]. fossil Biomass feedstocks can or be no produced with much life-cycle emissions fuels and withthatlittle competition with lower food
life-cycle emissions thangrown traditional fossil lands fuels abandoned and with little or no competition food productiongreenhouse-gas may include: perennial plants on degraded from agricultural use, cropwith residues, © 2017 Themay Authors. Published by Elsevier production include: perennial plantsLtd. grown on degraded lands abandoned from agricultural use, crop residues, Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. Tel.: +886-2-2362-5373; fax: +886-2-2392-8821. Keywords: Heat demand; Forecast; Climate change E-mail address:author. [email protected] * Corresponding Tel.: +886-2-2362-5373; fax: +886-2-2392-8821. E-mail address: [email protected]
1876-6102 Copyright © 2018 Elsevier Ltd. All rights reserved. Selection peer-review under responsibility the scientific 1876-6102and Copyright © 2018 Elsevier Ltd. All of rights reserved. committee of the Applied Energy Symposium and Forum 2018: Low carbon cities and urban energy systems, CUE2018. Selection and peer-review under responsibility of the scientific committee of the Applied Energy Symposium and 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Forum 2018: Low carbon cities urbanCommittee energy systems, Peer-review under responsibility of theand Scientific of The 15thCUE2018. International Symposium on District Heating and Cooling.
1876-6102 Copyright © 2018 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the CUE2018-Applied Energy Symposium and Forum 2018: Low carbon cities and urban energy systems. 10.1016/j.egypro.2018.09.092
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sustainably harvested wood and forest residues, double crops and mixed cropping systems, and municipal and industrial wastes [2]. In most cases, biomass is converted into fuels and chemicals by using biochemical and thermochemical processes. However, it is difficult to process the biomass biologically because of the natural resistance of plant cell walls to microbial and enzymatic deconstruction, collectively known as biomass recalcitrance [3]. Biomass can be used in a variety of thermochemical ways to provide energy: direct combustion to produce heat, gasification to produce gaseous fuels, and fast pyrolysis to produce liquid fuels [4]. The products of these thermochemical processes are divided into a volatile fraction consisting of gases, vapors and tar components, and a carbon-rich solid residue [5]. Microwaves are a portion of electromagnetic spectrum with wavelengths from 1 mm to 1 m, corresponding to frequencies between 300 MHz and 300 GHz [6–11]. Microwave heating is unique and offers a number of advantages over conventional heating processes, such as rapid and selective heating, quick start-up and stopping, and higher level of safety and automation [6]. Microwave heating is the transfer of electromagnetic energy to thermal energy and thus is energy conversion, rather than heat transfer [7], so there could be less or even negligible limitation caused by heat transfer in microwave processing. Microwave heating techniques are currently undergoing investigation for applications in various fields where the advantages of microwave radiation may lead to substantial savings in energy consumption, processing time, and environmental remediation [9]. A number of potential problems are inherent in microwave heating, including the phenomenon of hotspot formation [11]. Biomass pyrolysis assisted by microwave heating is a promising technique for the production of biofuels and chemicals [11– 17]. The most important advantage of microwave pyrolysis is the significant reduction in temperature (and thus savings in energy) observed for microwave pyrolysis compared with conventional pyrolysis, particularly for gas production [13]. A preliminary study of microwave pyrolysis has been presented in the previous article [18]. In this study, both product distribution and heating performance of microwave pyrolysis of various lignocellulosic biomass feedstocks were analyzed and discussed in depth. Besides, the solid yield of microwave pyrolysis of lignocellulosic biomass was compared with that of conventional pyrolysis. 2. Materials and methods 2.1. Materials The samples of this study were nine different lignocellulosic biomass feedstocks, such as rice straw (RS), rice husk (RH), corn stover (CS), sugarcane bagasse (SB), sugarcane peel (SP), coffee grounds (CG), bamboo leaves (BL), pennisetum grass (PG), and leucaena wood (LW), which were collected locally from factories, markets and farms. All the biomass feedstocks were naturally air-dried, shredded, and sieved by a 50-mesh (0.297 mm) screen prior to microwave pyrolysis and related characterization experiments. 2.2. Experimental device This study used a single-mode (focused) microwave device which operates at a frequency of 2.45 GHz. A schematic diagram of microwave pyrolysis system can be found elsewhere [19]. Both reaction tube (40 cm length, 5 cm outer diameter) and crucible (3 cm height, 4 cm outer diameter) were made of quartz. A K-type thermocouple sensor was placed against the bottom of the quartz crucible to measure the real-time temperature of biomass sample. Pure nitrogen gas was purged into the system at a flow rate of 50 mL/min to ensure anoxic condition in the reaction system. During the microwave pyrolysis experiments, reflected microwave power levels were lowered by adjusting a three-stub tuner and a short-circuit plunger. 2.3. Experimental procedure The shredded and sieved biomass feedstock (3–5 g) was added to the quartz crucible and then placed inside the quartz tube. The height of the quartz crucible was adjusted to be located in the path of microwave propagation. After sufficient purging was performed to maintain an inert atmosphere, the power supply was turned on and the microwave output was switched to a designated microwave power level (300, 400, and 500 W) for a designated
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processing time (30 min). The actual working microwave power level was determined by the incident power level subtracting the reflected power level. After the designated processing time, the power supply was turned off, and the carrier gas purging was stopped. The vapor produced during the experiment immediately passed through a condenser tube. The condensable and non-condensable parts of the product vapor were regarded as liquid and gaseous product, respectively. After self-cooled down to room temperature, the solid residue remaining in the quartz crucible was removed, weighed, and then stored in a desiccator. 3. Results and discussion 3.1. Biomass characteristics The general characteristics of lignocellulosic feedstocks are listed in Table 1. The combustible contents (volatile matter plus fixed carbon) of CS, SB, SP, and LW were relatively high (95–98 wt%), whereas those of RH and BL were lower (88–89 wt%). The carbohydrate content (hemicellulose plus cellulose) of SB was highest (approximately 74 wt%), whereas those of RH and BL were lowest (58–60 wt%). LW had the highest HHV (19.27 MJ/kg) whereas BL had the lowest (15.75 MJ/kg). According to the characteristics, CS, SB, SP, PG, and LW could have higher bioenergy potential, whereas the potential of RH and BL seems to be relatively low. Table 1. General characteristics of the lignocellulosic feedstocks. RS
RH
CS
SB
SP
CG
BL
PG
LW
9.32
6.34
8.58
8.61
5.30
7.97
7.14
8.32
10.50
Volatile matter
79.22
80.45
82.58
86.02
80.04
78.69
71.59
88.30
78.80
Fixed carbon
12.27
8.70
12.48
9.93
15.42
14.25
16.57
6.17
18.72
8.51
10.85
4.94
4.05
4.54
7.06
11.84
5.53
2.48
45.76
43.98
49.38
48.88
46.47
44.89
39.98
46.57
47.93
Moisture (wt%) Proximate analysis (wt%) a
Ash Ultimate analysis (wt%)
b
Carbon Hydrogen
6.22
5.94
6.52
6.71
6.23
6.14
5.81
6.27
6.59
Oxygenc
47.50
49.68
43.47
44.15
46.38
48.62
53.09
46.94
38.27
Nitrogen
0.52
0.40
0.63
0.27
0.92
0.35
1.12
0.22
7.21
Lignocellulosic analysis (wt%)b Extractives
4.39
5.52
5.27
5.44
8.18
12.35
5.28
5.18
7.53
Hemicellulose
31.12
28.03
28.94
27.40
26.40
30.03
25.55
29.07
26.56
Cellulose
38.14
30.42
43.97
46.55
41.11
33.10
34.14
35.52
37.36
Lignin
26.35
36.02
21.82
20.61
24.31
24.52
35.03
30.23
28.55
HHV (MJ/kg)
16.16
15.91
17.06
16.92
17.03
16.78
15.75
16.82
19.27
a
Dry basis. b Dry and ash-free basis. c Calculated by difference.
3.2. Microwave heating The maximum temperatures and heating rates of microwave pyrolysis of the nine biomass feedstocks at different microwave power levels are illustrated in Fig. 1. Both maximum temperature and heating rate increased with increasing microwave power level. Among these biomass feedstocks, the maximum temperatures of SP and BL were generally highest and lowest, respectively. Once again, the heating rates of SP and BL were generally highest and lowest, respectively. In general, the performance of microwave heating was positively correlated with the contents of volatile matter, cellulose, and carbon, but negatively correlated with the contents of ash, lignin, and
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oxygen. The composition of biomass could therefore have substantial effect on microwave heating, although the effect should be weaker than that of microwave power level.
Fig. 1. Maximum temperatures and heating rates of microwave pyrolysis at different microwave power levels.
A linear relationship between heating rate and microwave power level (R2 = 0.98) can be found by using the regression analysis:
HR 0.23MPL 14.33
(1)
where HR is the heating rate and MPL is the microwave power level. If HR is 0, MPL will be approximately 62 W that could be regarded as the minimum required microwave power level to initiate the microwave heating of lignocellulosic biomass. On the other hand, there was a logarithmic relationship between maximum temperature and microwave power level (R2 = 0.99): MT 231.88 ln( MPL) 924.48
(2)
where MT is the maximum temperature. When MT is assumed to be the room temperature (25 ºC), MPL will be approximately 60 W that could be regarded as the minimum required microwave power level to initiate the microwave heating of lignocellulosic biomass as well. The two MPL values are not so different, and their difference should be attributable to the uncertainty of temperature measurement or other experimental errors. 3.3. Product yield The three-phase product distributions of microwave pyrolysis of the lignocellulosic biomass feedstocks at a microwave power level of 500 W are illustrated in Fig. 2. Among these feedstocks, their gas yields ranged from 30
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wt% to 40 wt%, the liquid yields were in the range from 40 wt% to 48 wt%, and the solid yields were in the range from 16 wt% to 22 wt%. SB and CS had the highest gas yield, whereas RH had the lowest. On the contrary, RH had the highest liquid yield, whereas CS had the lowest.
Fig. 2. Three-phase product distributions of lignocellulosic biomass pyrolysis at a microwave power level of 500 W.
The concentrations of H2, CH4, CO, and CO2 were in the ranges of 18–25, 6–8, 51–59, and 10–14 vol%, respectively. Among these lignocellulosic biomass feedstocks, microwave pyrolysis of RS and RH produced more H2 whereas BL produced less. However, microwave pyrolysis of SP and BL produced more CO but RS, RH, and CG produced less. This could be attributable to their different elemental and lignocellulosic compositions, resulting in different microwave heating performance and reaction intensity. Besides, the formation and type of primary product (prior to secondary reactions) could be another crucial factor that needs to be further testified and verified. A comparison in solid yields of microwave pyrolysis and conventional pyrolysis of rice straw at various temperatures is illustrated in Fig. 3. As can be seen, the solid yield of microwave pyrolysis was substantially lower than that of conventional pyrolysis when both methods were carried out at the same temperature. This difference was up to approximately 30 wt% at the temperatures of 200–250 ºC, and it decreased to approximately 5 wt% at the temperatures of 300–500 ºC. Furthermore, the solid yield of microwave pyrolysis at approximately 500 ºC almost equals to the sum of fixed carbon and ash contents of rice straw, and thus the fixed carbon fraction of rice straw would start to be pyrolyzed at higher temperatures. However, conventional pyrolysis would need approximately 600 ºC for the pyrolysis of fixed carbon. In general, to achieve the same solid yield, the temperature required for conventional pyrolysis would be higher than that for microwave pyrolysis by approximately 100 ºC. Therefore, compared with conventional pyrolysis, microwave pyrolysis should be more energy-saving.
Fig. 3. A comparison in solid yields of microwave pyrolysis and conventional pyrolysis of rice straw.
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4. Conclusions The maximum temperature and heating rate of microwave pyrolysis of lignocellulosic biomass both increased with increasing microwave power level. The minimum required microwave power level could be approximately 60 W, which was determined according to the correlations of microwave power level with maximum temperature and heating rate. The difference in gaseous product compositions could be attributable to different elemental and lignocellulosic compositions, resulting in different microwave heating performance and reaction intensity. To achieve the same solid yield, the temperature required for conventional pyrolysis would be higher than that for microwave pyrolysis by approximately 100 °C. Microwave pyrolysis should be more energy-saving than conventional pyrolysis because of lower solid yield (i.e., higher devolatilization extent) and lower reaction temperature required. Acknowledgements The authors gratefully acknowledge the financial support from the Ministry of Science and Technology, Taiwan, ROC (104-2221-E-002-029-MY3). References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19]
Melero JA, Iglesias J, Garcia A. Biomass as renewable feedstock in standard refinery units. Feasibility, opportunities and challenges. Energy Environ Sci 2012;5:7393–420. Tilman D, Socolow R, Foley JA, Hill J, Larson E, Lynd L, et al. Beneficial biofuels—the food, energy, and environment trilemma. Science 2009;325:270–1. Himmel ME, Ding SY, Johnson DK, Adney WS, Nimlos MR, Brady JW, et al. Biomass recalcitrance: engineering plants and enzymes for biofuels production. Science 2007;315:804–7. Bridgwater AV, Meier D, Radlein D. An overview of fast pyrolysis of biomass. Org Geochem 1999;30:1479–93. Yaman S. Pyrolysis of biomass to produce fuels and chemical feedstocks. Energy Conv Manag 2004;45:651–71. Haque KE. Microwave energy for mineral treatment processes—a brief review. Int J Miner Process 1999;57:1–24. Thostenson ET, Chou TW. Microwave processing: fundamentals and applications. Compos Pt A-Appl Sci Manuf 1999;30:1055–71. Lidström P, Tierney J, Wathey B, Westman J. Microwave assisted organic synthesis—a review. Tetrahedron 2001;57:9225–83. Jones DA, Lelyveld TP, Mavrofidis SD, Kingman SW, Miles NJ. Microwave heating applications in environmental engineering—a review. Resour Conserv Recycl 2002;34:75–90. Kappe CO. Controlled microwave heating in modern organic synthesis. Angew Chem Int Ed 2004;43:6250–84. Appleton TJ, Colder RI, Kingman SW, Lowndes IS, Read AG. Microwave technology for energy-efficient processing of waste. Appl Energy 2005;81:85–113. Menéndez JA, Arenillas A, Fidalgo B, Fernandez Y, Zubizarreta L, Calvo EG, et al. Microwave heating processes involving carbon materials. Fuel Process Technol 2010;91:1–8. Luque R, Menéndez JA, Arenillas A, Cot J. Microwave-assisted pyrolysis of biomass feedstocks: the way forward? Energy Environ Sci 2012;5:5481–8. Lam SS, Chase HA. A review on waste to energy processes using microwave pyrolysis. Energies 2012;5:4209–32. Yin C. Microwave-assisted pyrolysis of biomass for liquid biofuels production. Bioresour Technol 2012;120:273–84. Mushtaq F, Mat R, Ani FN. A review on microwave assisted pyrolysis of coal and biomass for fuel production. Renew Sust Energ Rev 2014;39:555–74. Li J, Dai J, Liu G, Zhang H, Gao Z, Fu J, et al. Biochar from microwave pyrolysis of biomass: A review. Biomass Bioenerg 2016 ;94:228– 44. Lo SL, Huang YF , Chiueh PT , Kuan WH. Microwave pyrolysis of lignocellulosic biomass. Energy Procedia 2017;105:41–6. Huang YF , Chiueh PT , Kuan WH , Lo SL. Effects of lignocellulosic composition and microwave power level on the gaseous product of microwave pyrolysis. Energy 2015;89:974–81.