Influence of hydrothermal carbonized sewage sludge on coal water slurry performance

Abstract

Coal utilization, as a major energy source, raises sustainability concerns and environmental impacts, prompting researchers to explore blending it with other feedstocks. This study discusses hydrochar coal-water slurry (HC-CWS) preparation conditions, emphasizing apparent viscosity and exploring the influence of high ash content on char reactivity. The study highlights that the presence of free water in sludge is moderately influential, while high amounts of free water in raw sewage sludge (SS) and its near absence during hydrothermal carbonization (HTC) of SS are both unfavorable for enhancing the overall performance of coal-water slurry (CWS). HTC reduces the concentration of hydroxyl functional group, enhancing slurry performance and reducing ash content in HC-CWS, indicating that coal complements hydrochar (HC). High-temperature HC preparation is unsuitable for HC-CWS due to increased viscosity and decreased stability. In terms of ash content, the optimal pH and HC ratio for CWS are determined at 30% HC. The gasification reactivity of HC, prepared at 180 °C with a 30% HC ratio in CWS at R_0.5 is 6 × 10⁻³ and at R_0.9 is 9 × 10⁻³. However, increasing HC to 50% diminishes reactivity under CO₂ atmosphere. The inhibitory effect was observed with an increasing percentage of HC in CWS and the synergy factor decreased in the following order: 10% HC > 30% HC > 50% HC, i.e., from 1.04 to 0.35. The possible reason is the presence of high ash content and their similar initial gasification rates during its early stages.

Graphical abstract

Keywords

hydrochar coal water slurry / high ash content / slurry properties / gasification reactivity

References

[1] Numviyimana C , Warchoł J , Khalaf N , Leahy J J , Chojnacka K . Phosphorus recovery as struvite from hydrothermal carbonization liquor of chemically produced dairy sludge by extraction and precipitation. Journal of Environmental Chemical Engineering, 2022, 10(1): 106947

[2] Yang X , Wang B , Song X , Yang F , Cheng F . Co-hydrothermal carbonization of sewage sludge and coal slime with sulfuric acid for N, S doped hydrochar. Journal of Cleaner Production, 2022, 354: 131615

[3] Mosqueda A , Medrano K , Gonzales H , Yoshikawa K . Effect of hydrothermal and washing treatment of banana leaves on co-gasification reactivity with coal. Energy Procedia, 2019, 158: 785–791

[4] Zhu H , Yang Z , Yao Y , Ju X , Wang D , Liu Y , Zhang Y , Zhou A . Preparation of the modified sludge-semi-coke water slurry and analysis of its slurring performance and mechanism. Powder Technology, 2023, 413: 118039

[5] Wang L , Chang Y , Li A . Hydrothermal carbonization for energy-efficient processing of sewage sludge: a review. Renewable & Sustainable Energy Reviews, 2019, 108: 423–440

[6] Hu M , Hu H , Ye Z , Tan S , Yin K , Chen Z , Guo D , Rong H , Wang J , Pan Z . . A review on turning sewage sludge to value-added energy and materials via thermochemical conversion towards carbon neutrality. Journal of Cleaner Production, 2022, 379: 134657

[7] Peng C , Zhai Y , Zhu Y , Xu B , Wang T , Li C , Zeng G . Production of char from sewage sludge employing hydrothermal carbonization: char properties, combustion behavior and thermal characteristics. Fuel, 2016, 176: 110–118

[8] Chen X , Wang C , Wang Z , Zhao H , Liu H . Preparation of high concentration coal water slurry of lignite based on surface modification using the second fluid and the second particle. Fuel, 2019, 242: 788–793

[9] Zhang Y , Xu Z , Tu Y , Wang J , Li J . Study on properties of coal-sludge-slurry prepared by sludge from coal chemical industry. Powder Technology, 2020, 366: 552–559

[10] Chu R , Li Y , Meng X , Fan L , Wu G , Li X , Jiang X , Yu S , Hu Y . Research on the slurrying performance of coal and alkali-modified sludge. Fuel, 2021, 294: 120548

[11] Jiang X , Zhou Y , Meng X , Wu G , Miao Z , Sun F , Xu E . The effect of inorganic salt modification of sludge on the performance of sludge-coal water slurry. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2023, 664: 131146

[12] Li W , Li W , Liu H , Yu Z . Influence of sewage sludge on the slurryability of coal-water slurry. Fuel, 2009, 88(11): 2241–2246

[13] Liu M , Duan Y , Bikane K , Zhao L . Effect of waste liquid produced from the hydrothermal treatment of both low-rank coal and sludge on the slurryability of coal sludge slurry. Fuel, 2017, 203: 1–10

[14] Singh M K , Ratha D , Kumar S , Kumar D . Influence of particle-size distribution and temperature on rheological behavior of coal slurry. International Journal of Coal Preparation and Utilization, 2016, 36(1): 44–54

[15] Li D , Liu J , Wang S , Cheng J . Study on coal water slurries prepared from coal chemical wastewater and their industrial application. Applied Energy, 2020, 268: 114976

[16] Sjöström K , Chen G , Yu Q , Brage C , Rosén C . Promoted reactivity of char in co-gasification of biomass and coal: synergies in the thermochemical process. Fuel, 1999, 78(10): 1189–1194

[17] Wojtacha-Rychter K , Howaniec N , Smoliński A . Investigation of co-gasification characteristics of coal with wood biomass and rubber seals in a fixed bed gasifier. Renewable Energy, 2023, 20: 119725

[18] Howaniec N , Smoliński A . Biowaste utilization in the process of co-gasification with bituminous coal and lignite. Energy, 2017, 118: 18–23

[19] Guo S , Xu D , Guo X , Li X , Zhao C . Multi-response optimization of sewage sludge-derived hydrochar production and its CO₂-assisted gasification performance. Journal of Environmental Chemical Engineering, 2022, 10(1): 107036

[20] Gai C , Chen M , Liu T , Peng N , Liu Z . Gasification characteristics of hydrochar and pyrochar derived from sewage sludge. Energy, 2016, 113: 957–965

[21] Zheng X , Chen W , Ying Z , Huang J , Ji S , Wang B . Thermodynamic investigation on gasification performance of sewage sludge-derived hydrochar: effect of hydrothermal carbonization. International Journal of Hydrogen Energy, 2019, 44(21): 10374–10383

[22] Chen S , Sun Z , Zhang Q , Hu J , Xiang W . Steam gasification of sewage sludge with CaO as CO₂ sorbent for hydrogen-rich syngas production. Biomass and Bioenergy, 2017, 107: 52–62

[23] Khan S , Elkadi K , Janajreh I . Investigation of the co-gasification behavior of Kentucky coal and palm woody biomass. Procedia Computer Science, 2023, 224: 314–321

[24] Zdeb J , Howaniec N , Smoliński A . Utilization of carbon dioxide in coal gasification—an experimental study. Energies, 2019, 12(1): 140

[25] Smoliński A , Howaniec N , Bąk A . Utilization of energy crops and sewage sludge in the process of co-gasification for sustainable hydrogen production. Energies, 2018, 11(4): 809

[26] Lin C , Zuo W , Yuan S , Zhao P , Zhou H . EEffect of moisture on gasification of hydrochar derived from real-MSW. Biomass and Bioenergy, 2023, 178: 106976

[27] Yu M M , Masnadi M S , Grace J R , Bi X T , Lim C J , Li Y . Co-gasification of biosolids with biomass: thermogravimetric analysis and pilot scale study in a bubbling fluidized bed reactor. Bioresource Technology, 2015, 175: 51–58

[28] Liu J , Wang J , Chen C , Chen Y , Zheng X . Preparing coal slurry from organic wastewater to achieve resource utilization: slurrying performance and dispersant suitability. Fuel, 2023, 339: 126970

[29] Cavali M , Benbelkacem H , Kim B , Bayard R , Libardi Junior N , Gonzaga Domingos D , Woiciechowski A L , Castilhos A B . Co-hydrothermal carbonization of pine residual sawdust and non-dewatered sewage sludge-effect of reaction conditions on hydrochar characteristics. Journal of Environmental Management, 2023, 340: 117994

[30] Saetea P , Tippayawong N . Recovery of value-added products from hydrothermal carbonization of sewage sludge. International Scholarly Research Notices, 2013, 1: 268947

[31] Yang X , Wang B , Guo Y , Yang F , Cheng F . Insights into the structure evolution of sewage sludge during hydrothermal carbonization under different temperatures. Journal of Analytical and Applied Pyrolysis, 2023, 169: 105839

[32] Malhotra M , Garg A . Hydrothermal carbonization of sewage sludge: optimization of operating conditions using design of experiment approach and evaluation of resource recovery potential. Journal of Environmental Chemical Engineering, 2023, 11(2): 109507

[33] Malhotra M , Garg A . Hydrothermal carbonization of centrifuged sewage sludge: determination of resource recovery from liquid fraction and thermal behaviour of hydrochar. Waste Management, 2020, 117: 114–123

[34] Tan Y , Ma X , Xu Z , Zhang B , Osman S M , Luque R . Insights into acid-base properties of hydrotalcite materials during hydrothermal carbonization of sewage sludge. Journal of the Energy Institute, 2023, 110: 101349

[35] Zhang W , He Y , Wang Y , Li G , Chen J , Zhu Y . Comprehensive investigation on the gasification reactivity of pyrolysis residue derived from Ca-rich petrochemical sludge: roles of microstructure characteristics and calcium evolution. Energy Conversion and Management, 2022, 253: 115150

[36] He C , Giannis A , Wang J Y . Conversion of sewage sludge to clean solid fuel using hydrothermal carbonization: hydrochar fuel characteristics and combustion behavior. Applied Energy, 2013, 111: 257–266

[37] Huang W , Zhang R , Giannis A , Li C , He C . Sequential hydrothermal carbonization and CO₂ gasification of sewage sludge for improved syngas production with mitigated emissions of NO_x precursors. Chemical Engineering Journal, 2023, 454: 140239

[38] Petrovič A , Cenčič Predikaka T , Škodič L , Vohl S , Čuček L . Hydrothermal co-carbonization of sewage sludge and whey: enhancement of product properties and potential application in agriculture. Fuel, 2023, 350: 128807

[39] Liang W , Wang G , Jiao K , Ning X , Zhang J , Guo X , Li J , Wang C . Conversion mechanism and gasification kinetics of biomass char during hydrothermal carbonization. Renewable Energy, 2021, 173: 318–328

[40] Raheem A , Ding L , He Q , Hussain Mangi F , Hussain Khand Z , Sajid M , Ryzhkov A , Yu G . Effective pretreatment of corn straw biomass using hydrothermal carbonization for co-gasification with coal: response surface Methodology-Box Behnken design. Fuel, 2022, 324: 124544

[41] Moon J , Mun T Y , Yang W , Lee U , Hwang J , Jang E , Choi C . Effects of hydrothermal treatment of sewage sludge on pyrolysis and steam gasification. Energy Conversion and Management, 2015, 103: 401–407

[42] Zhang X , Ma M , Bai Y , Su W , Song X , Lv P , Wang J , Yu G . Torrefaction of sludge under CO₂ atmosphere to improve the fuel properties for high temperature gasification with coal. Thermochimica Acta, 2022, 713: 179249

[43] Wei J , Gong Y , Guo Q , Chen X , Ding L , Yu G . A mechanism investigation of synergy behaviour variations during blended char co-gasification of biomass and different rank coals. Renewable Energy, 2019, 131: 597–605

[44] Ma M , Wang J , Song X , Su W , Bai Y , Yu G . Co-gasification of cow manure and bituminous coal: a study on reactivity, synergistic effect, and char structure evolution. ACS Omega, 2020, 5(27): 16779–16788

[45] Yang H , Song H , Zhao C , Hu J , Li S , Chen H . Catalytic gasification reactivity and mechanism of petroleum coke at high temperature. Fuel, 2021, 293: 120469

[46] Huo W , Zhou Z , Chen X , Dai Z , Yu G . Study on CO₂ gasification reactivity and physical characteristics of biomass, petroleum coke and coal chars. Bioresource Technology, 2014, 159: 143–149

[47] Ding L , Zhang Y , Wang Z , Huang J , Fang Y . Interaction and its induced inhibiting or synergistic effects during co-gasification of coal char and biomass char. Bioresource Technology, 2014, 173: 11–20

[48] Satyam Naidu V , Aghalayam P , Jayanti S . Synergetic and inhibition effects in carbon dioxide gasification of blends of coals and biomass fuels of Indian origin. Bioresource Technology, 2016, 209: 157–165

[49] Zhang Y , Zheng Y , Yang M , Song Y . Effect of fuel origin on synergy during co-gasification of biomass and coal in CO₂. Bioresource Technology, 2016, 200: 789–794

[50] Howaniec N , Smoliński A . Influence of fuel blend ash components on steam co-gasification of coal and biomass—chemometric study. Energy, 2014, 78: 814–825

[51] Zhang Z , Zhang L , Liu Y , Lv M , You P , Wang X , Zhou H , Wang J . Co-gasification synergistic characteristics of sewage sludge and high-sodium coal. ACS Omega, 2023, 8(7): 6571–6583

[52] Mosqueda A , Wei J , Medrano K , Gonzales H , Ding L , Yu G , Yoshikawa K . Co-gasification reactivity and synergy of banana residue hydrochar and anthracite coal blends. Applied Energy, 2019, 250: 92–97

Competing interests

The authors declare that they have no competing interests.

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