Search

It is of importance to realize high-efficiency and clean utilization of fossil energy, especially for coal in China, while the development of oxy-fuel combustion technology is helpful to the large-scale capture of CO2. Meanwhile, oxy-fuel combustion can further lower the NOx emission observably. Semi-coke, a by-product of the coal chemical industry, has high calorific value and low volatile content. The mass fraction of volatile matter of semi-coke is about 5%-20%. The calorific value of lignite pyrolyzed semi-coke is generally 50–80% higher than that of raw lignite. Properly blending antibiotic filter residue with high volatility and semi-coke can improve the combustion characteristics. Both semi-coke and antibiotic filter residue have a large production, but less work has been performed on the oxy-fuel co-combustion of two fuels. The synergistic mechanism between these two fuels has yet to be fully understood. The synergistic mechanism between these two fuels has yet to be fully understood. In this work, the detailed physical–chemical properties of semi-coke and antibiotic filter residue were determined. The oxy-fuel co-combustion and co-pyrolysis characteristics of their blends were investigated by thermogravimetric analysis, with the synergies further evaluated using the interaction coefficient and relative root-mean-square error. The experimental results presented that the oxygen concentration mainly exerted influences on oxy-fuel co-combustion process during the stage of fixed carbon combustion beyond 400 °C. The synergies are enhanced with the oxygen content at oxygen concentrations ranging from 12 to 35%, while 45% oxygen content may inhibit the interactions between apparent fuels. The values of interaction coefficient in N2 atmosphere are very close to 1, so little synergy exists during pyrolysis. Meanwhile, mutual inhibition occurs between the component fuel during the pyrolysis of fuel with a semi-coke proportion of less than 60% in the CO2 atmosphere, and the two fuels promote each other as the percentage of semi-coke accounts for 80% of blending samples. This present work improved understanding of the co-processing of semi-coke and antibiotic filter residue is needed. The clean and efficient utilization of semi-coke is conducive to carbon neutrality and provides support for large-scale carbon capture. [ABSTRACT FROM AUTHOR]

Swine manure (SM) is one of the dominant livestock wastes in China. Pyrolysis is increasingly needed in valorizing SM into diverse products. However, little is known about the pyrolysis characteristics for SM. The results showed that the common-used solid-liquid separation in the SM management chain changed its physicochemical properties and pyrolysis characteristics. Specifically, the average activation energies (Ea) calculated by Flynn-Wall-Ozawa, Kissenger-Akahira-Sunose and Starink models for SM collected in pigsty (SM-A) were 184.70, 181.34 and 181.73 kJ/mol (R2 > 0.9) at conversion rate (a) = 0.2–0.7, respectively, which were increased by > 30 kJ/mol for solid-liquid separated SM (SM-B). Top pre-exponential values (A) for SM-A were also lower than these for SM-B. The ΔG and ΔS were decreased with the progressing of SM-A pyrolysis, while these for SM-B pyrolysis showed increases. Furthermore, SM-A pyrolysis produced more gas species than SM-B, which was more reactive during pyrolysis. Finally, this study suggested that although SM could be a potential energy source through the conversion by pyrolysis, attention should be paid on the impacts of manure management chain on SM pyrolysis. [Display omitted] • Swine manure (SM) from pigsty and after solid-liquid separation are compared. • Solid-liquid separated SM has distinct properties to SM excreted in pigsty. • SM from pigsty has a lower E a for pyrolysis than the solid-liquid separated SM. • More gaseous species are observed for the pyrolysis of SM from pigsty. • Manure management chain have impacts on pyrolysis characteristics of manure. [ABSTRACT FROM AUTHOR]

Zhundong coalfield is one super-huge coalfield newly discovered in China. However, ash-related problems have occurred due to its high content of alkali metals. Water washing is a possible approach to improve its utilization while little research was conducted on Zhundong coals. This study deals with the effect of water washing on alkali metal removal, thermal behaviors, and NO x emission of Zhundong coals. Experimental results show that water-soluble sodium is the predominant chemical form accounting for 70–92% of total sodium, while the case of potassium is different. The pore structure shows a considerable change after being washed. Sodium can be effectively removed while the removal ratio is closely related to water temperature and washing time. The mean apparent activation energy of coal pyrolysis decreases after being washed at low temperature, while high temperature of washing water hinders the pyrolysis. Certain sodium has a catalytic effect on pyrolysis while excessive sodium exhibits inhibitory influence. The conversions of fuel-N to NO and to N 2 O of washed coals are higher than those of raw coals. Water washing has a slight negative effect on NO x emission and combustion reactivity which is related to the catalytic effect of sodium within coal structure. [ABSTRACT FROM AUTHOR]

The study of combustion characteristics and kinetic parameters plays an important role in the determination of the coal fire combustion regime. Four Chinese coals from the Jurassic and Carboniferous-Permian periods were selected to study the influence of the geological time on the coal combustion characteristics. The thermogravimetry and differential scanning calorimetry with different heating rates were employed to identify the combustion characteristics and oxidation reaction kinetics of coal samples. It was found that a high heating rate could boost the characteristic temperatures of coal, and the curves characteristics of thermogravimetry and differential scanning calorimetry of all coal samples were the same. The ignition temperatures of coals from the Carboniferous-Permian period were lower than that of coals from the Jurassic period. During the coal combustion stage, the heat release of the Carboniferous-Permian coal samples was 166.86–2423.84 J/g, higher than that of the Jurassic coal samples. By Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink methods, it was found that the activation energy required for combustion reaction of Carboniferous-Permian coals was 37.18–88.95 kJ/mol, lower than that of Jurassic coals, revealing that the combustion performance of Carboniferous-Permian coals was superior to that of Jurassic coals. [Display omitted] • Effect of geological time on the combustion characteristics of coal was investigated. • The oxidation kinetics of Jurassic and Carboniferous-Permian coals were verified by multiple methods. • The spontaneous combustibility of Jurassic and Carboniferous-Permian coals was compared by combustion characteristics. • A high heating rate increases the characteristic temperature of coal in the high-temperature phase substantially. [ABSTRACT FROM AUTHOR]

Abstract: The treatment and disposal of sewage sludge have been one of the most significant environmental problems in China. Production of solid fuel from sewage sludge could be an effective way to work out this problem as it can realize the harmlessness treatment and recycling of these wastes simultaneously. This study proposed a novelty process, including the steam explosion (SE) pretreatment, mechanical dewatering, natural drying and pelleting, to produce solid fuel from sewage sludge. Dewatered sewage sludge with moisture content about 80% and the leaves of Chinese parasol were used as raw materials. A L 16(45) orthogonal table was employed to arrange the experiments to investigate the feasibility of the proposed process and optimize the operating parameters such as the ratio of sludge to leaves α and size of leaves S, pressure P and holding time H of the SE process. The range analysis and Analysis of Variance (ANOVA) were carried out to detect the optimal level within the observed range and the predominance of each factor. The thermogravimetric (TG) method was also adopted to characterize the combustion behaviors of these sludge derived fuel (SDF). The results show that no important factor has been omitted from the orthogonal design and the experimental results are consequently reliable. Considering only the SE operating parameters, the holding time H with a percentage contribution φH of 31.75% is the main influencing factor on the dewaterability of the SE treated products. With a holding time of 55s, the moisture of all the solid product is lower than 46.5% after mechanical dewatering with a press pressure of 1.0MPa for 1.5h. Moreover, the dewaterability of the SE products becomes better with the increase of the SE pressure. The optimal parameters to produce solid fuel from sewage sludge and leaves were α =2:1, H =70s, P =2.4MPa, and S =40mm within the range observed in this study. The wet base heating value of these fuels is more than 4000kJ·kg−1, which are capable of self-sustaining combustion. The TG analysis results show that these fuels have a good combustion performance with a low ignition point, narrow range of combustion temperature. The combustion process of these fuels includes three stages, which were evaporation of water, combustion of the volatile matters and fixed carbon respectively. Finally, an energy consumption model considering the main advantage was employed to investigate the economy of the process proposed in this study. All the data demonstrate the proposed process is powerful to control the water content and also an energy-savings method to produce solid fuel from bio-wastes. [Copyright &y& Elsevier]

China is the largest producer of traditional Chinese herbal medicine in the world. Chinese herbal medicine waste (CHHMW) is a byproduct of Chinese medicine factory and treated directly by landfill. In this way, untreated traditional CHHMW will cause more and more environmental problems. Therefore, it is urgent to reuse and hazard freely treat CHHMW. The CHHMW treated by thermochemical process is a better way than landfill. For this aim, in this paper, pyrolysis characteristics and kinetics of three CHHMWs were investigated by thermogravimetric analysis. The experiment results show, under the experimental condition, that heating rate and particle size have little impact on the pyrolysis process and the judgment of pyrolysis mechanism. The pyrolysis kinetic parameters of three CHHMWs under different heating rates were calculated using the modified Freeman-Carroll method. [ABSTRACT FROM AUTHOR]

Abstract: Moso bamboo (Phyllostachys pubesescens) is a major bamboo species which is widely used for temporary scaffolding in China. Its fast growing and low ash content make moso bamboo a potential renewable energy resource. In present work, thermal behaviors of moso bamboo and its lignocellulosic fractions were investigated using thermogravimetric analysis. Furthermore, to understand whether the delignification effect of white-rot fungi can promote the thermal decomposition of bamboo especially the lignin component, the changes in lignocellulose components as well as thermal behaviors of bamboo and acid detergent lignin were investigated. The results showed that the white-rot fungal pretreatment is advantageous to thermal decomposition of lignin in bamboo. The weight losses of ADL samples became greater and the thermal processes were accelerated after biopretreatment. The total pyrolysis weight loss increased from 57.14% to 65.07% for Echinodontium taxodii 2538 treated bamboo ADL sample. [Copyright &y& Elsevier]

Abstract: The aim of this work was to study the flammability of grassland fuels of the Songhua Jiang-Nen Jiang Plain in China. A Pyris Diamond TG-DTG was used, and the grassland materials examined were Aneurolepidium chinense, Chloris virgata, Phragmites communis, Suaeda corniculata, Lathyrus quinquenervius, Hemarthria japonica, Puccinellia chinampoensis, Calamagrostis epigejos, Medicago ruthenica and Lespedeza davurica. These species are very common in the Songhua Jiang-Nen Jiang Plain, and are frequently devastated by wildland fires. Mass loss is an important index for modelling wildland fires and for fire hazard studies on biomass fuels. In the TG-DTG curves, evaporation of a moisture peak and two dominating thermal oxidative degradation peaks were recorded. The relative data determined was used to compare the ignitability, combustibility and sustainability of the species. An index of integrated flammability was calculated for the examined species, and the relative flammability was ranked in the order: Medicago ruthenica>Suaeda corniculata>Lespedeza davurica>Lathyrus quinquenervius>Chloris virgata>Hemarthria japonica>Puccinellia chinampoensis>Phragmites communis>Calamagrostis epigejos>Aneurolepidium chinense. The flammability ranking of these natural fuels can be used in grassland fire management planning, fire behaviour modelling and fire hazard assessment. [Copyright &y& Elsevier]

Forest fuels are the basis of fire occurrences, while ground dead fuels are an important part of forest fuels. Undestanding the pyrolysis characteristics and gas emissions of forest fuels is of great significance to explore the effects of forest fire on atmospheric environment and carbon balance, as well as to prevent and combat forest fire. In this study, the thermogravimetric analysis and gas emission analysis were conducted on leaf litter of six tree species ( Pinus sylvestris var. mongolica , Picea koraiensis , Fraxinus mandshurica , Juglans mandshurica , Quercus mongolica , Betula platyphylla ) in Heilongjiang Province to explore the pyrolysis process and combustibility of forest fuels, to analyze their pyrolysis characteristics, pyrolysis kinetics characteristics, gas emission characteristics. A four-dimensional evaluation of their combustibility was conducted based on pyrolysis parameters. The results showed that the pyrolysis temperature of holocellulose in the leaves of those six tree species ranged in 143.31-180.48 ℃ at the beginning and 345.04-394.38 ℃ at the end, lignin pyrolysis temperature ranged in 345.04-394.38 ℃ at the beginning and 582.85-609.31 ℃ at the end. The pyrolysis of the six kinds of arbor blades during the pyrolysis process affected fuel ash content, quality and temperature of the total pyrolysis. The activation energies of two main pyrolysis stages of leaves of six tree species were 18.88-27.08 kJ·mol -1 and 13.25-27.54 kJ·mol -1 , respectively, and the pre-exponential factors were 3.13-26.28 min -1 and 1.30-22.55 min -1 . The holocellulose activation energy and pre-exponential factor of the pyrolysis stage for P. koraiensis , F. mandshurica , Q. mongolica , and B. platyphylla were greater than that of the lignin pyrolysis stage, while the opposite was true for P. sylvestris var. mongolica and J. mandshurica . The release amounts of CO and CO 2 at the pyrolysis stage of the holocellulose was 535.16-880.11 mg·m -3 and 7004.97-10302.05 mg·m -3 , and that at the pyrolysis stage of lignin was 240.31-1104.67 mg·m -3 and 20425.60-33946.68 mg·m -3 , respectively. The release of CO and CO 2 at the pyrolysis stage of healdellulose was less, but mass loss was greater than that at the pyrolysis stage of lignin. In the four-dimensional combustibility ranking of the six tree species leaves, B. platyphylla was the best ignitable, P. koraiensis was the most combustible, and P. sylvestris var. mongolica was the most sustainable and consumable. The ignitability was significantly positively correlated with pyrolysis kinetics parameters of the holocellulose, while the sustainability was negatively correlated with that of lignin.

Wastewater treatment plants produce millions of tons of sewage sludge. Sewage sludge is recognized as a promising feedstock for power generation via combustion and can be used for energy crisis adaption. We aimed to investigate the quantitative effects of various sludge characteristics on the overall sludge combustion process performance. Different types of sewage sludge were derived from numerous wastewater treatment plants in Beijing for further thermogravimetric analysis. Thermogravimetric-differential thermogravimetric curves were used to compare the performance of the studied samples. Proximate analytical data, organic compositions, elementary composition, and calorific value of the samples were determined. The relationship between combustion performance and sludge composition was also investigated. Results showed that the performance of sludge combustion was significantly affected by the concentration of protein, which is the main component of volatiles. Carbohydrates and lipids were not correlated with combustion performance, unlike protein. Overall, combustion performance varied with different sludge organic composition. The combustion rate of carbohydrates was higher than those of protein and lipid, and carbohydrate weight loss mainly occurred during the second stage (175-300°C). Carbohydrates have a substantial effect on the rate of system combustion during the second stage considering the specific combustion feature. Additionally, the combustion performance of digested sewage sludge is more negative than the others., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

This is the first study on the co-pyrolysis of spent substrate of Pleurotus ostreatus and coal tar pitch, and the activated carbon prepared from the pyrolytic char. Thermogravimetry (TG) analysis was carried out taking spent substrate, coal tar pitch and spent substrate-coal tar pitch mixture. The activation energies of pyrolysis reactions were obtained via the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods. The kinetic models were determined by the master-plots method. The activated carbons were characterised by N2-adsorption, Fourier transform infrared spectroscopy and X-ray diffraction. Experimental results demonstrated a synergistic effect happened during co-pyrolysis, which was characterised by a decreased maximum decomposition rate and an enhanced char yield. The average activation energies of the pyrolysis reactions of spent substrate, coal tar pitch and the mixture were 115.94, 72.92 and 94.38 kJ mol(-1) for the Flynn-Wall-Ozawa method, and 112.17, 65.62 and 89.91 kJ mol(-1) for the Kissinger-Akahira-Sunose method. The reaction model functions were f(α) = (1-α)(3.42), (1-α)(1.72) and (1-α)(3.07) for spent substrate, coal tar pitch and the mixture, respectively. The mixture char-derived activated carbon had a Brunauer-Emmett-Teller surface area up to 1337 m(2) g(-1) and a total pore volume of 0.680 cm(3) g(-1). Mixing spent substrate with coal tar pitch led to the creation of more micropores and a higher surface area compared with the single spent substrate and coal tar pitch char. Also, the mixture char-derived activated carbon had a higher proportion of aromatic stacking. This study provides a reference for the utilisation of spent substrate and coal tar pitch via co-pyrolysis, and their pyrolytic char as a promising precursor of activated carbon., (© The Author(s) 2014.)