Investigation on synergistic characteristics of sludge and lignite during co-hydrothermal carbonization

doi:10.11949/0438-1157.20190072

Abstract

Abstract:

The resource utilization of sludge has always been the focus of research by scholars. And their conversion into high quality solid fuels (hydrochars) via hydrothermal carbonization (HTC) is proved to be a promising potential technology. In this work, Co-HTC of sludge (sewage sludge, SS; deinking sludge, DS) and lignite (LC) was investigated to obtain a better preparation technology of sludge-derived hydrochars. The synergetic effect of mixing ratio (3∶7, 5∶5, 7∶3) on the HTC upgrading of sludge/LC mixtures was explored. And the combustion performance of hydrochars was also analyzed. The results have demonstrated that sludge/LC mixtures at a mixing ratio of 5∶5 have exhibited an optimal performance of hydrochar products. Specifically, the hydrochar yields can reach up to 81.08% and 86.00% for LC/SS and LC/DS, respectively. And high synergistic coefficients are observed in hydrochar yield (LC/SS-1.69%, LC/DS-0.18%), organics retention (LC/SS-11.90%, LC/DS-2.64%) and carbon retention (LC/SS-4.08%, LC/DS-0.77%), indicating a more remarkable synergetic effect of LC/SS than LC/DS. Besides, the higher heating value (HHV) and coalification degree of hydrochars can be enhanced by the increasing proportion of LC, which not only improves the fuel characteristics of hydrochars, but also makes it more stable and sufficient in the combustion process. These findings indicate that higher quality fuels can be obtained by Co-HTC pretreatment, thereby realizing the effective utilization of sludge/lignite.

Key words: sludge, lignite, co-hydrothermal carbonization, synergistic effects, products characterization

摘要：

污泥的资源化利用一直是国内外学者研究的焦点，对其进行水热提质处理后作为燃料应用是一种潜在的利用手段。本研究主要探讨城市污泥（SS）、脱墨污泥（DS）分别与褐煤（LC）以不同混合比例（3∶7、5∶5、7∶3）共水热碳化时的协同作用，并分析其固相产物（水热炭）的燃料品质。结果表明，当LC/SS、LC/DS混合比例为5∶5时，水热炭产率分别为81.08%和86.00%，并获得了最大协同系数（水热炭产率：1.69%和0.18%；有机物保留率：11.90%和2.64%；碳保留率：4.08%和0.77%）。其中，LC/SS的协同作用总是比LC/DS显著。随着LC添加量的增大，水热炭的热值和煤化程度均随之提高，不仅改善了水热炭的燃料特性，还使得燃烧过程更为稳定且充分。由此说明，通过共水热碳化预处理的方式可以制得较高品质的燃料，从而实现污泥/褐煤的有效利用。

关键词: 污泥, 褐煤, 共水热碳化, 协同作用, 燃料特性

CLC Number:

TK 6

Yanpei SONG, Xiuzheng ZHUANG, Hao ZHAN, Nantao WANG, Xiuli YIN, Chuangzhi WU. Investigation on synergistic characteristics of sludge and lignite during co-hydrothermal carbonization[J]. CIESC Journal, 2019, 70(8): 3132-3141.

宋艳培, 庄修政, 詹昊, 王南涛, 阴秀丽, 吴创之. 污泥与褐煤共水热碳化的协同特性研究[J]. 化工学报, 2019, 70(8): 3132-3141.

Figures/Tables 9

References 30

1	Saba A , Saha P , Reza M T . Co-hydrothermal carbonization of coal-biomass blend: influence of temperature on solid fuel properties[J]. Fuel Processing Technology, 2017, 167: 711-720.
2	Kambo H S , Dutta A . A comparative review of biochar and hydrochar in terms of production, physico-chemical properties and applications[J]. Renewable and Sustainable Energy Reviews, 2015, 45: 359-378.
3	Parshetti G , Liu Z , Jain A , et al . Hydrothermal carbonization of sewage sludge for energy production with coal[J]. Fuel, 2013, 111(3): 201-210.
4	Mun T Y , Tumsa T Z , Lee U , et al . Performance evaluation of co-firing various kinds of biomass with low rank coals in a 500 MWe coal-fired power plant[J]. Energy, 2016, 115: 954-962.
5	Zhuang X Z , Huang Y Q , Liu H C , et al . Relationship between physicochemical properties and dewaterability of hydrothermal sludge derived from different source[J]. Journal of Environmental Sciences, 2018, 69(7): 1-10.
6	Zhuang X Z , Zhan H , Huang Y Q , et al . Conversion of industrial biowastes to clean solid fuels via hydrothermal carbonization (HTC): upgrading mechanism in relation to coalification process and combustion behavior[J]. Bioresource Technology, 2018, 267: 17-29.
7	Liao J , Fei Y , Marshall M , et al . Hydrothermal dewatering of a Chinese lignite and properties of the solid products[J]. Fuel, 2016, 180: 473-480.
8	Wu J H , Wang J , Liu J Z , et al . Moisture removal mechanism of low-rank coal by hydrothermal dewatering: physicochemical property analysis and DFT calculation[J]. Fuel, 2017, 187: 242-249.
9	Liu J Z , Wu J H , Zhu J F , et al . Removal of oxygen functional groups in lignite by hydrothermal dewatering: an experimental and DFT study[J]. Fuel, 2016, 178: 85-92.
10	Alvarez R , Clemente C , Gomez-Limon D . The influence of nitric acid oxidation of low rank coal and its impact on coal structure [J]. Fuel, 2003, 82(15): 2007-2015.
11	Zhuang X Z , Huang Y Q , Song Y P , et al . The transformation pathways of nitrogen in sewage sludge during hydrothermal treatment[J]. Bioresource Technology, 2017, 245(Pt A): 463-470.
12	Zhang X J , Zhang L , Li A M . Hydrothermal co-carbonization of sewage sludge and pinewood sawdust for nutrient-rich hydrochar production: synergistic effects and products characterization[J]. Journal of Environmental Management, 2017, 201(2): 52-62.
13	Yao Z L , Ma X Q . Characteristics of co-hydrothermal carbonization on polyvinyl chloride wastes with bamboo[J]. Bioresource Technology, 2017, 247: 302-309.
14	王定美, 王跃强, 袁浩然, 等 . 水热炭化制备污泥生物炭的碳固定[J]. 化工学报, 2013, 64(7): 2625-2632.
	Wang D M , Wang Y Q , Yuan H R , et al . Carbon fixation of sludge biochar by hydrothermal carbonization[J]. CIESC Journal, 2013, 64(7): 2625-2632.
15	Liao Y F , Ma X Q . Thermogravimetric analysis of the co-combustion of coal and paper mill sludge[J]. Applied Energy, 2010, 87(11): 3526-3532.
16	Li F Y , Cao X D , Zhao L , et al . Effects of mineral additives on biochar formation: carbon retention, stability, and properties[J]. Environmental Science & Technology, 2014, 48(19): 11211-11217.
17	Tay J H , Chen X G , Jeyaseelan S , et al . Optimising the preparation of activated carbon from digested sewage sludge and coconut husk[J]. Chemosphere, 2001, 44(1): 45-51.
18	Seredych M , Bandosz T J . Tobacco waste/industrial sludge based desulfurization adsorbents: effect of phase interactions during pyrolysis on surface activity[J]. Environmental Science & Technology, 2007, 41(10): 3715-3721.
19	Xie C D , Liu J Y , Xie W M , et al . Quantifying thermal decomposition regimes of textile dyeing sludge, pomelo peel, and their blends[J]. Renewable Energy, 2018, 122: 55-64.
20	Xie C D , Liu J Y , Zhang X C , et al . Co-combustion thermal conversion characteristics of textile dyeing sludge and pomelo peel using TGA and artificial neural networks[J]. Applied Energy, 2018, 212: 786-795.
21	庄修政, 黄艳琴, 阴秀丽, 等 . 污泥水热处理制备清洁燃料的研究进展[J]. 化工进展, 2018, 37(1): 311-318.
	Zhuang X Z , Huang Y Q , Yin X L , et al . Research on clean solid fuel derived from sludge employing hydrothermal treatment[J]. Chemical Industry and Engineering Progress, 2018, 37(1): 311-318.
22	庄修政, 宋艳培, 詹昊, 等 .水热污泥与煤在混燃过程中的协同效应特性研究[J]. 燃料化学学报, 2018, 46(12): 1437-1446.
	Zhuang X Z , Song Y P , Zhan H , et al . Synergistic effects in co-combusting of hydrochar derived from sewage sludge with different-rank coals[J]. Journal of Fuel Chemistry and Technology, 2018, 46(12): 1437-1446.
23	Zornoza R , Moreno-Barriga E , Acosta J A , et al . Stability, nutrient availability and hydrophobicity of biochars derived from manure, crop residues, and municipal solid waste for their use as soil amendments[J]. Chemosphere, 2016, 144: 122-130.
24	Barbanera M , Cotana F , Di-Matteo U . Co-combustion performance and kinetic study of solid digestate with gasification biochar[J]. Renewable Energy, 2018, 121: 597-605.
25	He C , Giannis A , Wang J Y . Conversion of sewage sludge to clean solid fuel using hydrothermal carbonization: hydrochar fuel characteristics and combustion behavior[J]. Applied Energy, 2013, 111: 257-266.
26	He C , Wang K , Yang Y H , et al . Utilization of sewage-sludge-derived hydrochars toward efficient cocombustion with different-rank coals: effects of subcritical water conversion and blending scenarios[J]. Energy & Fuels, 2014, 28(9): 6140-6150.
27	Gil M V , Oulego P , Casal M D , et al . Mechanical durability and combustion characteristics of pellets from biomass blends[J]. Bioresource Technology, 2010, 101: 8859-8867.
28	Mursito A T , Hirajima T , Sasaki K . Upgrading and dewatering of raw tropical peat by hydrothermal treatment[J]. Fuel, 2010, 89(3): 635-641.
29	Peng C , Zhai Y B , Zhu Y , et al . Production of char from sewage sludge employing hydrothermal carbonization: char properties, combustion behavior and thermal characteristics[J]. Fuel, 2016, 176: 110-118.
30	Nonaka M , Hirajima T , Sasaki K . Upgrading of low rank coal and woody biomass mixture by hydrothermal treatment[J]. Fuel, 2011, 90(8): 2578-2584.

Sample	Proximate analysis/%(mass, db)			Ultimate analysis /%(mass,daf)					Fuel ratio	HHV / (J·g^-1)
Sample	A	VM	FC	C	H	O	N	S	Fuel ratio	HHV / (J·g^-1)
SS	56.11	37.57	6.32	48.46	8.20	34.61	7.59	1.14	0.17	9451
DS	66.02	32.65	1.33	57.45	7.18	32.19	2.59	0.59	0.04	5520
LC	6.73	48.41	44.86	65.70	5.02	27.84	0.90	0.54	0.93	24100

Sample	Proximate analysis/%(mass, db)			Ultimate analysis /%(mass,daf)					Fuel ratio	HHV / (J·g^-1)
Sample	A	VM	FC	C	H	O	N	S	Fuel ratio	HHV / (J·g^-1)
SS	56.11	37.57	6.32	48.46	8.20	34.61	7.59	1.14	0.17	9451
DS	66.02	32.65	1.33	57.45	7.18	32.19	2.59	0.59	0.04	5520
LC	6.73	48.41	44.86	65.70	5.02	27.84	0.90	0.54	0.93	24100

Sample		Proximate analysis/%(mass,db)			Ultimate analysis/%(mass,daf)					Fuel ratio
Sample		A	VM	FC	C	H	O	N	S	EV	CV	SC/%
LC/SS	L0∶S1	76.46	19.80	3.74	56.19	8.62	29.41	4.46	1.32	0.19	—	—
	L3∶S7	51.77	30.27	17.96	61.00	6.53	29.13	2.72	0.62	0.59	0.44	36.26
	L5∶S5	35.59	35.25	29.16	62.90	5.69	28.92	2.02	0.47	0.83	0.60	37.94
	L7∶S3	23.42	39.72	36.86	64.22	5.41	28.42	1.57	0.38	0.93	0.76	21.49
	L1∶S0	6.49	46.52	46.99	66.72	4.85	27.10	1.03	0.30	1.01	—	—
LC/DS	L0∶D1	70.61	25.53	3.86	59.54	7.04	32.13	0.92	0.37	0.15	—	—
	L3∶D7	50.40	33.45	16.15	62.06	5.83	30.83	0.92	0.36	0.48	0.41	18.01
	L5∶D5	37.04	36.29	26.67	63.50	5.51	29.75	0.92	0.32	0.73	0.58	26.55
	L7∶D3	24.37	40.71	34.92	64.83	5.45	28.48	0.93	0.31	0.86	0.75	13.97
	L1∶D0	6.49	46.52	46.99	66.72	4.85	27.10	1.03	0.30	1.01	—	—

Sample		Proximate analysis/%(mass,db)			Ultimate analysis/%(mass,daf)					Fuel ratio
Sample		A	VM	FC	C	H	O	N	S	EV	CV	SC/%
LC/SS	L0∶S1	76.46	19.80	3.74	56.19	8.62	29.41	4.46	1.32	0.19	—	—
	L3∶S7	51.77	30.27	17.96	61.00	6.53	29.13	2.72	0.62	0.59	0.44	36.26
	L5∶S5	35.59	35.25	29.16	62.90	5.69	28.92	2.02	0.47	0.83	0.60	37.94
	L7∶S3	23.42	39.72	36.86	64.22	5.41	28.42	1.57	0.38	0.93	0.76	21.49
	L1∶S0	6.49	46.52	46.99	66.72	4.85	27.10	1.03	0.30	1.01	—	—
LC/DS	L0∶D1	70.61	25.53	3.86	59.54	7.04	32.13	0.92	0.37	0.15	—	—
	L3∶D7	50.40	33.45	16.15	62.06	5.83	30.83	0.92	0.36	0.48	0.41	18.01
	L5∶D5	37.04	36.29	26.67	63.50	5.51	29.75	0.92	0.32	0.73	0.58	26.55
	L7∶D3	24.37	40.71	34.92	64.83	5.45	28.48	0.93	0.31	0.86	0.75	13.97
	L1∶D0	6.49	46.52	46.99	66.72	4.85	27.10	1.03	0.30	1.01	—	—

Sample	Residues /%(mass)	Characteristic temperatures /℃			(dw/dt)_max/ (%(mass)·min^-1)	(dw/dt)_mean/ (%(mass)·min^-1)	S×10⁸/ (min^-2·℃^-3)
Sample	Residues /%(mass)	T _i	T _m	T _b	(dw/dt)_max/ (%(mass)·min^-1)	(dw/dt)_mean/ (%(mass)·min^-1)	S×10⁸/ (min^-2·℃^-3)
SS	57.7	210.8	309.1	730.5	-1.81	-0.60	3.37
L0S1	76.6	222.7	313.3	711.3	-0.95	-0.34	0.92
L3S7	52.7	315.7	384.7	696.9	-5.25	-0.71	5.36
L5S5	37.5	319.7	371.1	681.1	-7.69	-0.96	10.60
L7S3	25.8	325.4	366.7	669.2	-9.74	-1.16	15.96
L1S0	9.0	333.3	364.5	662.1	-13.96	-1.44	27.32
DS	50.9	240.3	330.7	789.5	-1.57	-0.65	2.23
L0D1	60.3	292.1	338.9	772.3	-1.22	-0.53	0.99
L3D7	43.9	299.4	375.7	745.4	-3.38	-0.78	3.97
L5D5	34.0	310.2	375.0	740.4	-5.03	-0.93	6.56
L7D3	29.2	312.4	367.3	716.1	-5.87	-1.03	8.67
L1D0	9.0	333.3	364.5	662.1	-13.96	-1.44	27.32