Co-combustion Characteristics and Kinetic Analysis of Sediment From Dianchi Lake

doi:10.12096/j.2096-4528.pgt.23095

Abstract

Abstract:

Objectives Urban rivers and lakes often serve as carriers of sewage, with a large amount of sediment enriched with nitrogen and heavy metal elements. The combustion disposal method is clean, efficient, economical, and environmentally friendly. Studying the combustion kinetics of the sediment is crucial for its disposal and utilization. Methods The thermogravimetric analysis method is employed to compare and analyze the single combustion characteristics of the sediment in Dianchi Lake. In order to provide a reference for practical engineering applications, the sediment is co-combusted with coal at mixing ratios of 10%, 20%, and 30%. Using KAS, FWO, and Coats methods, 11 commonly used kinetic mechanism functions and solid-state reaction mechanism functions are selected to fit the activation energy and mechanism functions of each reaction stage. Results The combustion of sediment is divided into four stages. Compared with sludge and coal slurry, it has a lower ignition temperature, making it easier to burn, but a higher burnout temperature, indicating differences in the overall combustion characteristics. When sediment is burned at different heating rates, lower heating rates are more conducive to combustion. Co-combusting sediment with coal shows a synergistic effect, and their interaction has a positive impact on the combustion characteristics. As the mixing ratio increases, the ignition performance improves. However, when the mixing ratio reaches 30%, the combustibility index significantly decreases, indicating that excessive mixing ratio is detrimental to improving the combustion performance of the fuel. The final fitting shows that the reaction mechanisms in the second and third stages of the combustion process are consistent, while the fourth stage is different. Conclusions Sediment can be used as a fuel, burning of sediment and coal can improve the ignition performance of coal and conducive to the stable combustion of coal, but the mixing ratio should not exceed 30%. The research results provide a reference for practical engineering applications.

Key words: sediment, thermogravimetric experiment, combustion of sediment, combustion properties, kinetic analysis, apparent activation energy, reaction mechanism function, mixing ratio

CLC Number:

TK 16

Xinyu ZHENG, Jialin CHEN, Fei ZHANG, Suilin WANG, Lei LIU, Peng YUAN, Qi WU, Zhong HUANG. Co-combustion Characteristics and Kinetic Analysis of Sediment From Dianchi Lake[J]. Power Generation Technology, 2025, 46(1): 180-189.

Figures/Tables 21

Tab. 1 Industrial and elemental analysis of experimental material

样品	工业分析				元素分析
样品	M_ad	A_ad	V_ad	F_C,ad	C_d	H_d	O_d	N_d	S_d
滇池底泥	6.70	66.30	25.10	1.80	12.74	2.22	11.07	0.66	0.31
红河污泥	6.49	52.52	38.97	2.02	21.37	3.56	15.12	3.00	0.79
山东煤泥	1.29	43.06	22.07	32.95	39.96	2.52	11.45	0.73	0.37
红河褐煤	20.15	22.41	39.83	37.76	54.13	6.19	13.52	1.19	2.55

Fig. 1 XRD analysis of Dianchi Lake sediment and lignite

Tab. 2 XRF analysis of sediment before and after dehydration

样品	物质质量分数
样品	SiO₂	Al₂O₃	CaO	Fe₂O₃	K₂O	TiO₂	MgO	SO₃
底泥(脱水)	50.16	19.32	14.43	7.47	3.19	1.91	1.51	1.75
底泥	66.73	14.90	3.30	5.71	4.61	1.89	0.99	0.87
褐煤	35.54	29.14	10.58	8.84	0.91	1.31	1.28	11.78

Fig. 2 STA449F3 comprehensive thermal analyzer

Tab. 3 Reaction mechanism function

机理函数	$G (α)$	机理函数	$G (α)$
Jander二维扩散	$[1 - (1 - α) 12] 2$	Avrami-Erofeev方程 $($ n=1.5)	$[- l n (1 - α)] 1.5$
Jander三维扩散	$[1 - (1 - α) 13] 2$	Avrami-Erofeev方程 $($ n=2)	$[- l n (1 - α)] 2$
反Jander三维扩散	$[(1 + α) 13 - 1] 2$	Avrami-Erofeev方程 $($ n=3)	$[- l n (1 - α)] 3$
ZLT三维扩散	$[1 / (1 - α) 13 - 1] 2$	收缩球状(体积)	$1 - (1 - α) 13$
Mample单行法则	$- l n (1 - α)$	化学反应(2级)	$(1 - α - 1) - 1$
Valensi二维扩散	$α + (1 - α) l n (1 - α)$

Tab. 3 Reaction mechanism function

机理函数	$G (α)$	机理函数	$G (α)$
Jander二维扩散	$[1 - (1 - α) 12] 2$	Avrami-Erofeev方程 $($ n=1.5)	$[- l n (1 - α)] 1.5$
Jander三维扩散	$[1 - (1 - α) 13] 2$	Avrami-Erofeev方程 $($ n=2)	$[- l n (1 - α)] 2$
反Jander三维扩散	$[(1 + α) 13 - 1] 2$	Avrami-Erofeev方程 $($ n=3)	$[- l n (1 - α)] 3$
ZLT三维扩散	$[1 / (1 - α) 13 - 1] 2$	收缩球状(体积)	$1 - (1 - α) 13$
Mample单行法则	$- l n (1 - α)$	化学反应(2级)	$(1 - α - 1) - 1$
Valensi二维扩散	$α + (1 - α) l n (1 - α)$

Fig. 3 TG curves of sediment at different heating rates

Fig. 4 TG curves under different sample heating rates of 20 K/min operating conditions

Tab. 4 Ignition temperature, burnout temperature, and weight loss under different heating rates

升温速率/(K/min)	着火温度/℃	燃尽温度/℃	TG/%
10	245.4	741.3	52.20
20	257.3	746.7	69.46
30	258.1	743.9	71.52

Fig. 5 DTG curves of sediment at different heating rates

Fig. 6 DTG curves under different sample heating rates of 20 K/min operating conditions

Tab. 5 Reaction temperature range of sediment at different stages under different heating rate

反应阶段	底泥升温速率
反应阶段	10 K/min	20 K/min	30 K/min
1	30.0~245.4	30.0~240.7	30.0~248.6
2	245.4~449.2	240.7~457.2	248.6~452.5
3	449.25~653.1	457.25~673.8	452.5~656.4
4	653.1~741.4	673.8~746.7	656.4~743.9

Fig. 7 TG curves of different proportions mixed at a heating rate of 20 K/min

Fig. 8 DTG curves of different proportions mixed at a heating rate of 20 K/min

Fig. 9 Experimental and theoretical TG-DTG curve of blending under different blending ratios

Fig. 10 Characteristics of 10%, 20%, and 30% mixed combustion of bottom mud and lignite

Fig. 11 tropic of different equal conversion rates fitted by KAS method

Fig. 12 tropic of different equal conversion rates fitted by FWO method

Tab. 6 Two methods for fitting the average Ea values of each stage

反应阶段	表观活化能平均值/(kJ/mol)
反应阶段	FWO	KAS
2(α=0.1~0.55)	126.042 267 9	123.668 620 9
3(α=0.6~0.8)	206.459 811 5	191.462 116 4
4(α=0.8~0.9)	491.233 700 3	512.002 159 2

Tab. 7 Coats method fitting parameters

阶段	机理函数	斜率a	截距b	活化能E	相关系数
2、3	Avrami-EROfeev(n=3)	-15 353.3	8.71	127.64	0.91
4	ZLT	-58 327.6	30.84	484.93	0.91

Fig. 13 Tropic of different mechanism functions fitted by Coats method in the fourth stage

Fig. 14 Tropic of different mechanism functions fitted by Coats method in the second and third stages

References 20

1	JING L D， WU C X， LIU J T，et al ．The effects of dredging on nitrogen balance in sediment-water microcosms and implications to dredging projects[J]．Ecological Engineering，2013，52：167-174． doi:10.1016/j.ecoleng.2012.12.109
2	韩卫博，卞双，汪涛，等．燃煤电厂脱硫废水及污泥中重金属污染物控制研究进展[J]．发电技术，2020，41(5)：497-509． doi:10.12096/j.2096-4528.pgt.20064
	HAN W B， BIAN S， WANG T，et al ．Research progress on control of heavy metals pollutants in desulfurization wastewater and sludge of coal-fired power plants[J]．Power Generation Technology，2020，41(5)：497-509． doi:10.12096/j.2096-4528.pgt.20064
3	张宏伟，张永生，汪涛，等．电厂燃煤飞灰固化脱硫污泥重金属铅特性研究[J]．发电技术，2024，45(3)：527-534．
	ZHANG H W， ZHANG Y S， WANG T，et al ．Study on the characteristics of heavy metal lead in desulfurization sludge solidified by coal-fired fly ash in power plant[J]．Power Generation Technology，2024，45(3)：527-534．
4	王彦霖，贾里，王碧茹，等．城市污泥和煤泥混燃过程中交互作用的影响及机理[J]．中南大学学报(自然科学版)，2022，53(10)：4174-4184．
	WANG Y L， JIA L， WANG B R，et al ．Influence and mechanism of interaction in co-combustion of sewage sludge and coal slime[J]．Journal of Central South University (Science and Technology)，2022，53(10)：4174-4184．
5	何必繁，王里奥，黄川．重庆城市污泥燃烧及动力学特性分析[J]．中国电机工程学报，2010，30(35)：32-37．
	HE B F， WANG L A， HUANG C ．Study on combustion characteristics and kinetics of Chongqing municipal sewage sludge[J]．Proceedings of the CSEE，2010，30(35)：32-37．
6	李爱民，刘淑静，王伟云．大物料量污泥燃烧机理及表观动力学特性[J]．燃烧科学与技术，2009，15(5)：381-387．
	LI A M， LIU S J， WANG W Y ．Combustion mechanism and apparent kinetic characteristics of massive sewage sludge sample[J]．Journal of Combustion Science and Technology，2009，15(5)：381-387．
7	罗立群，周鹏飞，涂序．湖泊底泥燃烧特性及其热动力学分析[J]．中国矿业，2019，28(6)：149-154．
	LUO L Q， ZHOU P F， TU X ．Combustion characteristics and thermodynamic analysis of lake sediments[J]．China Mining Magazine，2019，28(6)：149-154．
8	刘秀如，吕清刚，赵科．城市污水污泥热解特性及动力学研究[J]．热能动力工程，2010，25(6)：677-680．
	LIU X R， LÜ Q G， ZHAO K ．Pyrolysis characteristics and kinetic study of urban sewage water and sludge[J]．Journal of Engineering for Thermal Energy and Power，2010，25(6)：677-680．
9	胡艳军，宁方勇，钟英杰．城市污水污泥热解特性及动力学规律研究[J]．热能动力工程，2012，27(2)：253-258．
	HU Y J， NING F Y， ZHONG Y J ．Study on pyrolysis characteristics and kinetics of municipal sewage sludge[J]．Journal of Engineering for Thermal Energy and Power，2012，27(2)：253-258．
10	HU M， CHEN Z， GUO D，et al ．Thermogravimetric study on pyrolysis kinetics of Chlorella pyrenoidosa and bloom-forming cyanobacteria[J]．Bioresource Technology，2015，177：41-50． doi:10.1016/j.biortech.2014.11.061
11	JIANG C， ZHOU W， BI H，et al ．Co-pyrolysis of coal slime and cattle manure by TG-FTIR-MS and artificial neural network modeling：Ppyrolysis behavior，kinetics，gas emission characteristics[J]．Energy，2022，247：123203． doi:10.1016/j.energy.2022.123203
12	任宁，张建军．热分析动力学数据处理方法的研究进展[J]．化学进展，2006，18(4)：410-416．
	REN N， ZHANG J J ．Progress in datum treatment methods of thermal analysis kinetics[J]．Progress in Chemistry，2006，18(4)：410-416．
13	段妮娜，王磊磊，朱勇，等．河湖底泥的来源、性质和处理处置技术：与污水厂污泥的比较[J]．城市道桥与防洪，2019(12)：166-170．
	DUAN N N， WANG L L， ZHU Y，et al ．Sources，properties and treatment and disposal technologies of river bottom sludge：comparison with sewage plant sludge[J]．Urban Roads Bridges & Flood Control，2019(12)：166-170．
14	LIU C， LIU J， SUN G，et al ．Thermogravimetric analysis of (co-) combustion of oily sludge and litchi peels：combustion characterization，interactions and kinetics[J]．Thermochimica Acta，2018，667：207-218． doi:10.1016/j.tca.2018.06.009
15	CHEN J， MU L， CAI J，et al ．Pyrolysis and oxy-fuel combustion characteristics and kinetics of petrochemical wastewater sludge using thermogravimetric analysis[J]．Bioresource Technology，2015，198：115-123． doi:10.1016/j.biortech.2015.09.011
16	LI J， FAN S， ZHANG X，et al ．Investigation on co-combustion of coal gasification fine ash and raw coal blends：thermal conversion，gas pollutant emission and kinetic analyses[J]．Energy，2022，246：123368． doi:10.1016/j.energy.2022.123368
17	LÓPEZ-GONZÁLEZ D， FERNANDEZ-LOPEZ M， VALVERDE J L，et al ．Kinetic analysis and thermal characterization of the microalgae combustion process by thermal analysis coupled to mass spectrometry[J]．Applied Energy，2014，114：227-237． doi:10.1016/j.apenergy.2013.09.055
18	李朝阳，牛胜利，韩奎华，等．次烟煤与半焦富氧混燃特性热重分析[J]．燃料化学学报，2022，50(8)：937-953． doi:10.1016/s1872-5813(21)60002-1
	LI C Y， NIU S L， HAN K H，et al ． Thermogravimetric analysis on the characteristics of oxy-fuel co-combustion of sub-bituminous coal and semi-coke[J]．Journal of Fuel Chemistry and Technology，2022，50(8)：937-953． doi:10.1016/s1872-5813(21)60002-1
19	CHEN Z， LI J， GUAN S，et al ．Kinetics，thermodynamics and gas evolution of atmospheric circulating fluidized bed coal gasification fly ash combustion in air atmosphere[J]．Fuel，2021，290：119810． doi:10.1016/j.fuel.2020.119810
20	段一航，高宁博，全翠．水热处理对含油污泥热解特性及动力学影响[J]．化工进展，2023，42(2)：603-613．
	DUAN Y H， GAO N B， QUAN C ．Effect of hydrothermal treatment on pyrolysis characteristics and kinetics of oily sludge[J]．Chemical Industry and Engineering Progress，2023，42(2)：603-613．