褐煤水热提质改善水煤浆的成浆性、流变性和稳定性的实验研究

吴君宏

褐煤水热提质改善水煤浆的成浆性、流变性和稳定性的实验研究

吴君宏^,

浙江省发展规划研究院, 浙江杭州 310012

详细信息

中图分类号: TQ536
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- 被引次数: 0
出版历程
- 收稿日期: 2018-10-15
- 修回日期: 2019-01-13
- 网络出版日期: 2021-01-23
- 刊出日期: 2019-03-10

Hydrothermal dewatering of lignite to improve the slurry-ability, rheology, and stability of coal-water slurry

WU Jun-hong^,

Zhejiang Development & Planning Institute, Hangzhou 310012, China

More Information

Corresponding author: WU Jun-hong, E-mail: garywu@zju.edu.cn

摘要

摘要: 采用水热法对小龙潭褐煤进行提质处理，从煤质特性、含氧基团、表面亲水性和粒度分布等因素，探究了水热提质对褐煤水煤浆成浆浓度、流变特性以及稳定性的影响。结果表明，水热提质脱除了褐煤中的水分，氧含量降低，煤阶升高。水热提质脱除了褐煤中含氧基团，煤水表面接触角增大，褐煤表面亲水性得到改善。小龙潭褐煤颗粒粒度呈现双峰分布，水热提质后褐煤颗粒粒径减小且趋于规则。水热提质改善了水煤浆的成浆性能，成浆浓度由提质前的44.09%，最高可提升到61.94%。在相近的表观黏度下，水热提质后水煤浆的稠度系数K减小，流变指数n增大，水热提质在降低浆体黏度的同时，仍保持假塑性流体特征。水热提质降低水煤浆的析水率，延缓了浆体出现硬沉淀的时间，改善浆体的稳定性。水热提质从理化特性对褐煤进行深度改性，从而获得高浓度，假塑性以及稳定性良好的符合工业应用的水煤浆。
- 水热提质 /
- 褐煤 /
- 水煤浆 /
- 成浆特性 /
- 流变特性
Abstract: Xiaolongtan lignite was upgraded by hydrothermal dewatering (HTD). The main factors affecting slurry-ability of the lignite including coal property, oxygen functional groups, surface hydrophilicity, and particle size distribution were analyzed. The effect of HTD on solid concentration, rheology, and stability of the upgraded coal was also investigated. The results show that a substantial amount of moisture was removed, oxygen content decreased, and the coal rank was enhanced by HTD upgrading. The contact angle between coal and water increased after removal of oxygen functional groups by HTD, thereby improving surface property of the upgraded lignite. A typical bimodal distribution of the lignite particle size was observed. The mean particle diameter of lignite decreased and the lignite particles became more regular after HTD. HTD upgrading significantly improved slurry-ability of the lignite. The solid concentration of raw coal was 44.09%, while that of the upgraded coal after HTD increased to 61.94%. The consistency coefficient K decreased, while the rheological index n increased for the CWS prepared from the upgraded coals. HTD upgrading decreased the apparent viscosity, and maintained the shear-thinning behavior of pseudo-plastic fluid. Moreover, as the water separation ratio decreased and formation of hard sedimentation was delayed, stability of the CWS was enhanced after HTD upgrading. Overall, the physico-chemical properties of Xiaolongtan lignite were significantly modified after HTD, thus a high-quality slurry fuel with high solid concentration, superior pseudo-plastic behavior, and good stability could be achieved.
- hydrothermal dewatering /
- lignite /
- coal-water slurry /
- slurry-ability /
- rheology

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图 1 水热反应系统装置示意图

Figure 1 Schematic of the hydrothermal reaction system

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图 2 原煤及水热提质煤C(1s)的XPS谱图

Figure 2 XPS spectra (C 1s) of raw and hydrothermally dewatered coals

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图 3 煤样接触角与氧含量的关联

Figure 3 Relationship between contact angle and oxygen content in coal during HTD upgrading

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图 4 原煤及水热提质煤的粒径分布

Figure 4 Particle-size distribution of raw and hydrothermally dewatered coals

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图 5 水热提质前后褐煤的黏度-浓度特性

Figure 5 Viscosity-concentration dependence of coal water slurry before and after HTD upgrading

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图 6 水煤浆的表观黏度-剪切速率关系曲线

Figure 6 Dependence between apparent viscosity and shear rate

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图 7 水煤浆的剪切应力-剪切速率关系曲线

Figure 7 Dependence between shear stress and shear rate

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图 8 水热提质前后褐煤水煤浆的析水率

Figure 8 Water separation ratio of coal water slurry before and after HTD upgrading

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表 1 原煤和水热提质煤的煤质分析

Table 1 Coal property analyses of raw coal and hydrothermally dewatered coals

Sample	Proximate analysis w_ad/%				Q_b, _ad /(MJ·kg^-1)	Ultimate analysis w_d/%					O/C atomic ratio
Sample	M	A	V	FC	Q_b, _ad /(MJ·kg^-1)	C	H	N	O	S_t	O/C atomic ratio
Raw coal	16.44	12.12	39.09	32.35	18.15	56.00	3.64	1.49	22.05	2.32	29.5
HTD-200	11.26	13.70	38.24	36.80	20.59	59.05	3.76	1.71	17.76	2.28	22.6
HTD-250	9.30	14.60	36.48	39.62	21.98	60.83	3.84	1.78	15.19	2.26	18.7
HTD-300	6.21	15.65	34.83	43.31	23.28	63.96	4.14	1.86	11.14	2.21	13.1

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表 2 原煤与水热提质煤的官能团相对百分含量

Table 2 Relative contents of different functional groups in raw and upgraded coals

Sample	Content w/%
	C-C/C-H	C-O	C=O	O=C- O
	284.8 eV	286.1 eV	287.5 eV	289.0 eV
Raw coal	64.52	25.26	6.37	3.85
HTD-200	67.88	22.37	6.29	3.26
HTD-250	71.30	20.84	5.61	2.25
HTD-300	76.95	16.53	4.64	1.88

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表 3 原煤及水热提质煤的粒径参数

Table 3 Parameters of particle diameter in raw and hydrothermally dewatered coals

Sample	Parameters of particle diameter /μm
Sample	D_mean	D₁₀	D₅₀	D₉₀
Raw coal	50.57	5.28	38.25	116.8
HTD-200	39.84	4.07	27.61	95.82
HTD-250	33.20	3.68	23.00	78.54
HTD-300	30.07	3.42	20.93	68.90

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表 4 水热提质前后褐煤的定黏浓度

Table 4 Fixed-viscosity concentration of coal water slurry before and after HTD upgrading

Sample	Raw coal	HTD-200	HTD-250	HTD-300
Fixed-viscosity concentration/%	44.09	55.42	58.96	61.94

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表 5 水热提质前后褐煤水煤浆的流变特性参数

Table 5 Parameters of rheological property for coal water slurry before and after HTD upgrading

Sample	η_c/(mPa·s)	K/(Pa·s)	n	R²
Raw coal	990.5	7.05	0.568	0.999
HTD-200	1022.0	4.25	0.675	0.993
HTD-250	1019.0	3.80	0.716	0.987
HTD-300	987.1	2.59	0.803	0.994

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