气体加压烘焙对玉米秸秆提质及热解特性的影响

高攀; 赵泽衡; 刘禹彤; 郭得忠; 杨少霞

doi:10.1016/S1872-5813(21)60190-1

气体加压烘焙对玉米秸秆提质及热解特性的影响

doi: 10.1016/S1872-5813(21)60190-1

1.
华北电力大学新能源学院, 北京 102206
2.
国网甘肃刘家峡水电厂, 甘肃临夏 731100
3.
华北电力大学水利与水电工程学院, 北京 102206

基金项目: 国家自然科学基金(51776070, 51206045)和中央高校基金(2018MS033)资助

详细信息

通讯作者:
E-mail：gaopan@ncepu.edu.cn

中图分类号: TK6
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出版历程
- 收稿日期: 2021-10-19
- 修回日期: 2021-12-06
- 录用日期: 2021-12-29
- 网络出版日期: 2022-01-11
- 刊出日期: 2022-06-25

Effect of gas-pressurized torrefaction on the upgrading and pyrolysis characteristics of corn stalk

1.
School of New Energy, North China Electric Power University, Beijing 102206, China
2.
State Grid Gansu Liujiaxia Hydropower Plant, Linxia 731100, China
3.
School of water conservancy and Hydropower Engineering, North China Electric Power University, Beijing 102206, China

Funds: The project was supported by the National Natural Science Foundation of China (51776070, 51206045) and the Fundamental Research Funds for Central Universities (2018MS033)

摘要

摘要: 在不同温度及压力下对玉米秸秆进行了烘焙，通过元素分析、FT-IR、TGA以及固定床热解等方式分析了烘焙产物的理化特性与热解特性，研究了气体加压烘焙对生物质燃料特性及热转化行为的影响，结果表明，烘焙样品的脱氧效率及能量密度均随烘焙温度的升高而增加；在相同质量收率时，加压烘焙所需温度比常压烘焙低约40 ℃，且能量收率、碳收率、脱氧效率以及烘焙产物的能量密度分别为常压烘焙的1.125、1.142、1.539和1.131倍；加压烘焙样品比常压烘焙表现出更好的疏水性，且更易于脱水；当烘焙温度为250 ℃时，加压烘焙样品热解气相产物中CH₄和H₂含量分别为常压烘焙的2.135和1.439倍；加压烘焙样品热解液相产物中酚类相对含量增加，最高可达51.11%，而呋喃类和酸类物质含量则明显下降。相较于常压烘焙，加压烘焙在相同温度下对生物质具有更好的提质效果。
- 玉米秸秆 /
- 加压烘焙 /
- 提质 /
- 热解特性
Abstract: Corn straw was torrefied under at different temperatures and the torrefied products were characterized by proximate analysis, ultimate analysis, FT-IR, TGA and pyrolysis experiments; the effect of gas-pressurized torrefaction on the upgrading and pyrolysis characteristics of corn stalk was investigated. The results indicate that the deoxidation efficiency and energy density of torrefied products under both atmospheric pressure (AP) and gas pressured (GP) conditions increase with the increase of torrefaction temperature. The temperature required for GP torrefaction is almost 40 °C lower than that for AP torrefaction to obtain the same mass yield. The energy yield, carbon yield, deoxidation efficiency and the energy density of GP-torrefied corn straw are 1.125, 1.142, 1.539 and 1.131 times higher than those of AP-torrefied one, respectively. The GP-torrefied corn straw shows better hydrophobicity and is easier to dehydrate. In addition, the pyrolysis of GP-torrefied corn straw produces significantly higher fractions of CH₄ and H₂ in the gaseous product than the pyrolysis of AP-torrefied one; meanwhile, the relative content of phenols in the liquid products for the pyrolysis of GP-torrefied samples also increases up to 51.11%, whereas the contents of furans and acids decrease considerably. All these suggest that GP torrefaction performs better in biofuel upgrading than AP torrefaction under the same temperature.
- corn stalk /
- gas-pressurized torrefaction /
- upgrading /
- pyrolysis characteristics

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FIG. 1594. FIG. 1594.

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图 1 不同烘焙条件下的质量收率与能量收率(a)、氧脱除效率(b)以及碳收率(c)

Figure 1 Mass yield and energy yield (a), oxygen removal efficiency (b) and carbon yield (c) of various torrefied corn stalk samples under different conditions

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图 2 原生及烘焙玉米秸秆的 Van Krevelen 图

Figure 2 Van Krevelen diagram of raw and torrefied corn stalks

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图 3 不同压力下加压烘焙的质量收率与能量收率(a)、氧脱除效率(b)以及碳收率(c)

Figure 3 Mass yield and energy yield (a), oxygen removal efficiency (b) and carbon yield (c) for the torrefaction of corn stalks under different pressures at 250 ℃

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图 4 原生及烘焙玉米秸秆的吸水特性(a)与脱水特性(b)曲线

Figure 4 Water absorption (a) and desorption (b) curves of the raw and torrefied corn stalk samples

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图 5 原生(a)及烘焙(b)玉米秸秆的FT-IR光谱谱图

Figure 5 FT-IR spectra of the raw (a) and torrefied (b) corn stalk samples under different torrefaction conditions

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图 6 原生(a)及烘焙(b)玉米秸秆的TG和DTG曲线

Figure 6 TG and DTG curves of the raw (a) and torrefied (b) corn stalk samples

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图 7 常压烘焙(a)和加压烘焙(b)玉米秸秆的热解动力学补偿效应

Figure 7 Kinetic compensation effect for the pyrolysis of the torrefied biomass samples obtained from AP torrefaction (a) and GP torrefaction (b)

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图 8 加压烘焙强化提质原理示意图

Figure 8 Schematic diagram of gas pressured torrefaction for biomass upgrading

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图 9 常压烘焙(a)及加压烘焙(b)玉米秸秆热解三相产物产率

Figure 9 Pyrolysis product distribution of AP (a) and GP (b) torrefied corn straw

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图 10 常压烘焙(a)及加压烘焙(b)玉米秸秆热解气相产物组分分布

Figure 10 Gas product distribution of AP- (a) and GP-torrefied (b) corn straw samples

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图 11 原生及烘焙玉米秸秆热解液相产物组分分布

Figure 11 Liquid product distribution of raw and torrefied corn stalk

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表 1 玉米秸秆灰分的XRF成分分析

Table 1 XRF analysis of corn stalk ash

Sample	Content w/%
Sample	SiO₂	K₂O	CaO₂	MgO	P₂O₅	Al₂O₃	Fe₂O₃	Na₂O
Corn stalk	44.01	17.97	9.48	7.13	5.92	3.13	2.47	0.59

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表 2 原生及烘焙玉米秸秆的基本性质

Table 2 Basic properties of raw and torrefied biomass samples

Sample	Proximate analysis w/%（dry base）			Elemental analysis w/%（dry base）				Q_HHV/(MJ·kg⁻¹)
Sample	V	FC	A	C	H	O*	N	Q_HHV/(MJ·kg⁻¹)
Raw	72.67	19.63	7.70	43.70	5.34	40.43	2.83	17.65
180-AP	72.42	19.84	7.74	44.73	5.21	40.23	2.09	17.91
210-AP	71.09	21.12	7.79	44.95	5.14	40.12	2.00	17.97
230-AP	68.06	22.63	9.31	45.25	5.18	38.22	2.04	18.09
250-AP	66.56	22.30	11.14	45.42	4.89	36.29	2.26	18.15
180-GP-5	65.40	26.0	8.60	50.12	4.97	34.36	1.95	19.82
210-GP-5	55.51	31.22	13.27	52.14	4.76	27.69	2.14	20.53
230-GP-5	53.82	31.58	14.60	55.00	4.79	23.49	2.12	21.67
250-GP-5	48.96	35.79	15.25	57.37	4.80	19.97	2.62	22.71
250-GP-1	48.49	36.38	15.13	57.02	4.80	20.36	2.69	22.58
250-GP-3	48.92	36.02	15.06	57.48	4.81	20.02	2.63	22.77
250-GP-7	48.53	35.88	15.59	58.20	4.79	18.79	2.63	23.06
O*：calculated by difference

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表 3 不同温度5 MPa加压烘焙需要的初始压力与加压能耗

Table 3 Initial pressure and energy consumption for 5 MPa GP torrefaction at different temperatures

Torrefaction temperature/℃	Initial pressure/MPa	Energy consumption/MJ
180	3.29	2.87
210	3.09	2.65
230	2.96	2.51
250	2.85	2.39

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表 4 原生及烘焙样品的热解特性参数

Table 4 Pyrolysis parameters of the raw and torrefied corn stalk samples

Sample	t_i/℃	t_p/℃	R_max/(%·min⁻¹)	R_v/(%·min⁻¹)	w_f/%	Δt_1/2/℃	D_i/10⁻⁷
Raw	199.00	320.40	5.88	0.92	12.06	252.67	3.65
180-AP	231.00	325.96	5.52	0.93	19.75	250.00	2.93
210-AP	247.71	327.28	6.52	0.92	20.65	268.55	2.99
230-AP	260.99	326.69	6.74	0.90	22.68	286.56	2.76
250-AP	287.49	326.45	2.74	0.61	41.73	299.33	0.98
180-GP	235.64	316.11	4.38	0.93	20.04	272.83	2.15
210-GP	240.74	320.46	3.81	0.77	32.88	285.45	1.73
230-GP	237.19	319.87	2.56	0.69	40.05	283.15	1.19
250-GP	267.92	432.99	1.32	0.55	47.16	288.87	0.40

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表 5 原生及烘焙样品的动力学参数

Table 5 Kinetic parameters for the pyrolysis of raw and torrefied corn straw samples.

Sample	Temperature range/℃	E/(kJ·mol⁻¹)	A/min⁻¹	R²
Raw	220−350	37.99	1.14×10⁴	0.9989
180-AP	220−350	55.43	5.09×10⁵	0.9849
210-AP	220−350	70.97	1.32×10⁷	0.9900
230-AP	220−350	81.47	9.89×10⁷	0.9970
250-AP	220−350	68.44	1.15×10⁷	0.9929
180-GP	220−350	49.07	7.61×10⁴	0.9974
210-GP	220−350	49.73	7.79×10⁴	0.9985
230-GP	220−350	41.17	9.38×10³	0.9984
250-GP	220−450	34.11	8.05×10²	0.9851

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