Effect of hydrothermal oxidation pretreatment on the physicochemical properties of fuel pellets prepared from cotton stalks

doi:10.16085/j.issn.1000-6613.2021-1935

Abstract

Abstract:

Cotton stalk (CS) was first pretreated by hydrothermal oxidation (HTO) process in an autoclave at 180—280℃ and then densified to prepare fuel pellets. The effect of HTO temperature on the physicochemical properties of the resulted CS pellets was investigated by thermogravimetric analyzer, X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FTIR), etc. The results indicated that the resulted CS yield decreased with the increase of HTO temperature. The hemicellulose contained in CS decomposes completely before HTO temperature reached to 180℃, the amorphous cellulose decomposed before 200℃, the crystalline cellulose decomposed before 260℃, and the relative content of the lignin gradually increased. The cellulose crystallinity of the resulted CS showed a decreasing trend as HTO temperature increases. The fixed carbon yield, the calorific value and the energy density of the resulted CS pellet increased, but the combustion characteristic became worse. The apparent density of the resulted CS pellet remained around 1300kg/m3, and the compressive strength decreased with increasing HTO temperature. The compressive strength of the pellet prepared from CS pretreated at 180℃ was the maximum, which increased by 183.33% compared with that from the raw material. The key factors affecting the compressive strength were crystalline cellulose which could act as a skeleton support and pseudo-lignin which acted as binder. The fuel pellet from CS pretreated at 180℃ showed the best combustion characteristic and physical properties with the calorific value of 17.76MJ/kg, the energy density of 23.44GJ/m³, and the compressive strength of 11.9MPa. The resulted indicated that the biomass pellets could be used as high-quality solid fuels.

Key words: cotton stalk, fuel pellet, hydrothermal oxidation, mechanical properties, combustion characteristic

摘要：

以棉秆为研究对象，经180~280℃水热氧化预处理后热压制备成型颗粒。利用热重分析、X射线衍射（XRD）及傅里叶变换红外光谱（FTIR）等分析手段，考察了水热氧化预处理温度对棉秆成型颗粒理化性能及燃烧性能的影响。结果表明：随着水热氧化温度的升高，棉秆的固相产物产率降低，半纤维素于180℃之前完全分解，无定形纤维素于200℃完全分解，结晶纤维素于260℃完全分解，水热氧化固相产物的纤维素结晶度呈现逐渐减小的趋势，而木质素相对含量增加；棉秆成型颗粒的固定碳含量、热值和能量密度增加，但燃烧性能变差。水热氧化预处理后棉秆成型颗粒的表观密度保持在1300kg/m3左右，抗压强度则随着水热氧化温度的增加而下降，其中180℃水热氧化预处理后棉秆成型颗粒的抗压强度相比原料成型燃料增加了183.33%。本研究范围内，经180℃水热氧化预处理后获得的棉杆成型颗粒的燃烧性能和物理性能最佳，其热值为17.76MJ/kg，能量密度为23.44GJ/m³，抗压强度达11.90MPa，可作为优质生物质成型燃料使用。

关键词: 棉秆, 成型颗粒, 水热氧化, 机械性能, 燃烧特性

CLC Number:

YANG Jifan, ZHANG Shouyu, CAO Zhongyao, LANG Sen, LIU Simeng, ZHOU Yi, HU Nan, WU Yuxin. Effect of hydrothermal oxidation pretreatment on the physicochemical properties of fuel pellets prepared from cotton stalks[J]. Chemical Industry and Engineering Progress, 2022, 41(8): 4417-4424.

杨济凡, 张守玉, 曹忠耀, 郎森, 刘思梦, 周义, 胡南, 吴玉新. 水热氧化预处理对棉秆成型颗粒理化性质的影响[J]. 化工进展, 2022, 41(8): 4417-4424.

Figures/Tables 10

References 29

1	中华人民共和国国家能源局. 生物质能发展“十三五规划”[Z]. 2016-10-15.
	National Energy Administration. Biomass energy development“The 13th Five-Year Plan”[Z]. 2016-10-15.
2	WANG Z W, LEI T Z, YANG M, et al. Life cycle environmental impacts of cornstalk briquette fuel in China[J]. Applied Energy, 2017, 192: 83-94.
3	ANAND V, SUNJEEV V, VINU R. Catalytic fast pyrolysis of Arthrospira platensis (spirulina) algae using zeolites[J]. Journal of Analytical and Applied Pyrolysis, 2016, 118: 298-307.
4	崔旭阳, 杨俊红, 雷万宁, 等. 生物质成型燃料制备及燃烧过程添加剂应用及研究进展[J]. 化工进展, 2017, 36(4): 1247-1257.
	CUI Xuyang, YANG Junhong, LEI Wanning, et al. Recent progress in research and application of DBBF additive in preparation and combustion process[J]. Chemical Industry and Engineering Progress, 2017, 36(4): 1247-1257.
5	BEIG B, RIAZ M, RAZA NAQVI S, et al. Current challenges and innovative developments in pretreatment of lignocellulosic residues for biofuel production: a review[J]. Fuel, 2021, 287: 119670.
6	张帅, 王贤华, 李攀, 等. 预处理法提高生物质热解产物品质的研究进展[J]. 化工进展, 2014, 33(2): 346-352.
	ZHANG Shuai, WANG Xianhua, LI Pan, et al. Research progress in pretreatment method for the quality improvement of biomass pyrolysis products[J]. Chemical Industry and Engineering Progress, 2014, 33(2): 346-352.
7	金放鸣. 模拟自然加快碳循环: 水热转化生物质为高附加值产品[J]. 化工进展, 2010, 29(1): 1-10.
	JIN Fangming. Speed up the carbon cycle by mimicking nature: hydrothermal conversion of biomass into value-added products[J]. Chemical Industry and Engineering Progress, 2010, 29(1): 1-10.
8	FANG Guigan, LIU Shanshan, SHEN Kuizhong, et al. Wet oxidation pretreatment of poplar waste for enhancing enzymatic hydrolysis efficiency[J]. Paper and Biomaterials, 2017, 2(2): 8-17.
9	WANG C W, ZHANG S Y, WU S Y, et al. Effect of oxidation processing on the preparation of post-hydrothermolysis acid from cotton stalk[J]. Bioresource Technology, 2018, 263: 289-296.
10	孙梦圆, 张守玉, 王才威, 等. 棉秆水热及水热氧化过程水相产物分析研究[J]. 化工学报, 2020, 71(5): 2382-2388.
	SUN Mengyuan, ZHANG Shouyu, WANG Caiwei, et al. Aqueous products prepared by hydrothermal and hydrothermal oxidation processes of cotton stalk[J]. CIESC Journal, 2020, 71(5): 2382-2388.
11	VASSILEV S V, BAXTER D, ANDERSEN L K, et al. An overview of the organic and inorganic phase composition of biomass[J]. Fuel, 2012, 94: 1-33.
12	SEGAL L, CREELY J J, MARTIN A E, et al. An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer[J]. Textile Research Journal, 1959, 29(10): 786-794.
13	WU S Y, ZHANG S Y, WANG C W, et al. High-strength charcoal briquette preparation from hydrothermal pretreated biomass wastes[J]. Fuel Processing Technology, 2018, 171: 293-300.
14	MOON C, SUNG Y, AHN S, et al. Effect of blending ratio on combustion performance in blends of biomass and coals of different ranks[J]. Experimental Thermal and Fluid Science, 2013, 47: 232-240.
15	PENG X W, MA X Q, XU Z B. Thermogravimetric analysis of co-combustion between microalgae and textile dyeing sludge[J]. Bioresource Technology, 2015, 180: 288-295.
16	FLÓREZ PARDO L M, SALCEDO MENDOZA J G, LÓPEZ GALÁN J E. Influence of pretreatments on crystallinity and enzymatic hydrolysis in sugar cane residues[J]. Brazilian Journal of Chemical Engineering, 2019, 36(1): 131-141.
17	LENG E W, ZHANG Y, PENG Y, et al. In situ structural changes of crystalline and amorphous cellulose during slow pyrolysis at low temperatures[J]. Fuel, 2018, 216: 313-321.
18	ILANIDIS D, WU G C, STAGGE S, et al. Effects of redox environment on hydrothermal pretreatment of lignocellulosic biomass under acidic conditions[J]. Bioresource Technology, 2021, 319: 124211.
19	ZHU G K, YANG L, GAO Y, et al. Characterization and pelletization of cotton stalk hydrochar from HTC and combustion kinetics of hydrochar pellets by TGA[J]. Fuel, 2019, 244: 479-491.
20	KARIMI K, TAHERZADEH M J. A critical review of analytical methods in pretreatment of lignocelluloses: composition, imaging, and crystallinity[J]. Bioresource Technology, 2016, 200: 1008-1018.
21	SHINDE S D, MENG X Z, KUMAR R, et al. Recent advances in understanding the pseudo-lignin formation in a lignocellulosic biorefinery[J]. Green Chemistry, 2018, 20(10): 2192-2205.
22	STEFANIDIS S D, KALOGIANNIS K G, ILIOPOULOU E F, et al. A study of lignocellulosic biomass pyrolysis via the pyrolysis of cellulose, hemicellulose and lignin[J]. Journal of Analytical and Applied Pyrolysis, 2014, 105: 143-150.
23	LI S Q, SONG H, HU J H, et al. CO₂ gasification of straw biomass and its correlation with the feedstock characteristics[J]. Fuel, 2021, 297: 120780.
24	CAO Z Y, ZHANG S Y, HUANG X H, et al. Correlations between the compressive strength of the hydrochar pellets and the chemical components: evolution and densification mechanism[J]. Journal of Analytical and Applied Pyrolysis, 2020, 152: 104956.
25	孔令照. 生物质废弃物水热资源化处理过程及机理研究[D]. 上海: 同济大学, 2008.
	KONG Lingzhao. Research on hydrothermal reutilization process and mechanics of biomass wastes[D]. Shanghai: Tongji University, 2008.
26	LEE J T E, KHAN M U, TIAN H L, et al. Improving methane yield of oil palm empty fruit bunches by wet oxidation pretreatment: mesophilic and thermophilic anaerobic digestion conditions and the associated global warming potential effects[J]. Energy Conversion and Management, 2020, 225: 113438.
27	REZA M T, LYNAM J G, VASQUEZ V R, et al. Pelletization of biochar from hydrothermally carbonized wood[J]. Environmental Progress & Sustainable Energy, 2012, 31(2): 225-234.
28	WANG C W, ZHANG S Y, HUANG S, et al. Effect of hydrothermal treatment on biomass structure with evaluation of post-pyrolysis process for wood vinegar preparation[J]. Fuel, 2021, 305: 121513.
29	霍丽丽, 赵立欣, 郝彦辉, 等. 国内外生物质成型燃料质量标准现状[J]. 农业工程学报, 2020, 36(9): 245-254.
	HUO Lili, ZHAO Lixin, HAO Yanhui, et al. Quality standard system of densified biomass fuels at home and abroad[J]. Transactions of the Chinese Society of Agricultural Engineering, 2020, 36(9): 245-254.

样品	T₀/℃	DTG_max/%·min^-1	T_max/℃
CS-RAW	67.56	5.01	337.38
CS-HTO180	127.52	20.47	350.02
CS-HTO200	149.33	18.66	342.01
CS-HTO230	193.25	10.04	350.75
CS-HTO260	215.52	4.35	396.47
CS-HTO280	217.01	4.07	411.30

样品	T₀/℃	DTG_max/%·min^-1	T_max/℃
CS-RAW	67.56	5.01	337.38
CS-HTO180	127.52	20.47	350.02
CS-HTO200	149.33	18.66	342.01
CS-HTO230	193.25	10.04	350.75
CS-HTO260	215.52	4.35	396.47
CS-HTO280	217.01	4.07	411.30

样品	工业分析/%				热值/MJ·kg^-1	能量密度/GJ·m^-3
样品	水分（M_ad）	灰分（A_ad）	挥发分（V_daf）	固定碳（FC_daf）	热值/MJ·kg^-1	能量密度/GJ·m^-3
CS-RAW-B	10.73	2.92	86.87	13.13	17.36	20.89
CS-HTO180-B	5.78	2.35	81.05	18.95	17.76	23.44
CS-HTO200-B	6.09	2.92	75.34	24.66	19.31	25.76
CS-HTO230-B	5.92	2.93	66.11	33.89	22.03	29.35
CS-HTO260-B	3.63	2.01	58.59	41.41	24.61	32.02
CS-HTO280-B	4.01	2.06	54.76	45.24	26.35	34.15
ISO 17225标准	≤10				≥16.5

样品	工业分析/%				热值/MJ·kg^-1	能量密度/GJ·m^-3
样品	水分（M_ad）	灰分（A_ad）	挥发分（V_daf）	固定碳（FC_daf）	热值/MJ·kg^-1	能量密度/GJ·m^-3
CS-RAW-B	10.73	2.92	86.87	13.13	17.36	20.89
CS-HTO180-B	5.78	2.35	81.05	18.95	17.76	23.44
CS-HTO200-B	6.09	2.92	75.34	24.66	19.31	25.76
CS-HTO230-B	5.92	2.93	66.11	33.89	22.03	29.35
CS-HTO260-B	3.63	2.01	58.59	41.41	24.61	32.02
CS-HTO280-B	4.01	2.06	54.76	45.24	26.35	34.15
ISO 17225标准	≤10				≥16.5

样品	V_mean /%·min^-1	V_max /%·min^-1	T_i/℃	T_f/℃	S×10⁷ /%²·(min²·℃³)^-1
RAW-B	2.40	6.35	231.16	420.51	6.78
CS-HTO180-B	2.10	9.21	258.32	446.79	6.49
CS-HTO200-B	2.12	7.73	260.63	449.81	5.35
CS-HTO230-B	2.07	4.14	259.43	452.03	2.82
CS-HTO260-B	1.99	2.93	266.56	470.03	1.74
CS-HTO280-B	2.10	3.47	271.53	463.72	2.13