Numerical simulation of heat transfer properties of large-sized biomass particles during pyrolysis process.

During the pyrolysis process of large particles, the conduction between particles cannot be ignored. In the present work, a numerical simulation model for the pyrolysis of biomass particles was established, which takes into account the conduction within the particles. Based on this model, the temperature distribution inside the particle during the pyrolysis process was determined and the effects of particle size, moisture content, and gas velocity on heat transfer characteristics were analyzed. The results showed that the temperatures at different positions of the particles along the inflow direction were quite different, and the maximum temperature difference inside the particles was about 146.7 K for a particle diameter of 10 mm and a velocity of 0.2 m/s. During the pyrolysis process of biomass particles, there were two peaks of Nusselt number. The increase of moisture content prolonged the pyrolysis time. The pyrolysis. time of particles with moisture content of 15 % was about 1.5 times longer than that of dry particles when the particle diameter was 10 mm. Increasing the particle size decreased the difference between the two peaks and increased the time interval between the two peaks. Increasing the gas velocity can improve the heat transfer, but the effect of too high gas velocity on improving the heat transfer is limited. The present study is of great importance for a detailed understanding of the pyrolysis process of biomass particles.

Stabilizing Li-Rich Layered Cathode Materials Using a LiCoMnO4 Spinel Nanolayer for Li-Ion Batteries.

Lithium-rich cathodes have excess lithium in the transition metal layer and exhibit an extremely high specific capacity and good energy density. However, they still have some disadvantages. Here, we propose LiCoMnO4, a new nanolayer coating material with a spinel structure, to modify the surface of lithium cathode oxide (Li7/6Mn1/2Ni1/6Co1/6O2) with a layered structure. The designed cathode with nanolayer spinel coating delivers an excellent reversible capacity, outstanding rate capability, and superior cycling ability whilst exhibiting discharge capacities of 300, 275, 220, and 166 mAh g-1 at rates of 0.1 C at 2.0-4.8 V formation and 0.1, 1, and 5 C, respectively, between 2.0 and 4.6 V. The cycling ability and voltage fading at a high operational voltage of 4.9 V were also investigated, with results showing that the nanolayer spinel coating can depress the surface of the lithium cathode oxide layer, leading to phase transformation that enhances the electrochemical performance.

[Application of special acupoints for chronic gastritis in ancient literature of acupuncture and moxibustion].

The application of special acupoints for different primary symptoms of chronic gastritis in ancient literature of acupuncture and moxibustion was analyzed and summarized. With keywords, electronic and manual retrieval of ancient literature being performed to establish a database, the association rules were performed with SPSS Modeler 18. As a result, ① among all the 2243 items included, 109 items mentioned special acupoints (excluding those only mentioned crossing acupoint). The frequency of special acupoints was 2554 (71.7%), and the special acupoints on the spleen meridian, the stomach meridian, the conception vessel were frequently used. The frequency of five-shu point was highest, followed by front-mu points. ② The special acupoints for four main primary symptoms of chronic gastritis, "stomachache" "vomiting and regurgitation" "belching and acid regurgitation" and "epigastric fullness", included Zusanli (ST 36), Neiguan (PC 6), Zhongwan (CV 12), Gongsun (SP 4), Taibai (SP 3). In addition, the back-shu points were also selected to treat the primary symptoms other than "epigastric fullness". Zhangmen (LR 13) was added to treat "belching and acid regurgitation". The combination of Neiguan (PC 6) and Gongsun (SP 4) showed the strongest correlation; due to different primary symptoms, the combination had different emphasis.

AHP-based approach for optimization of waste disposal method in urban functional zone.

In this study, the municipal solid waste (MSW) is considered as one kind of energy source in urban planning scheme instead of a trash stream. Considering the characteristics of MSW from different urban functional zones and the current energy supply modes, an evaluation model for waste-to-energy (WtE) method was set up based on the analytical hierarchy process technique. The model consists of three layers: 15 fundamental indices, 4 influencing factors based on fundamental indices and the target functions supported by influencing factors. Taking an urban functional region of a city in north China as the research object, 4 alternatives are compared according to their weights and the sensitivities of the influencing factors are analyzed. The result will provide guide for the disposal method of WtE in new urban district planning and old urban redevelopment.

[Evaluation of integrated control measures for soil-transmitted nematodiasis in Jinhu County, Jiangsu Province].

OBJECTIVE: To evaluate the effect of integrated control measures on soil-transmitted nematodiasis so as to provide the evidence for formulating the appropriate control strategies and measures in Jinhu County, Jiangsu Province. METHODS: Since 1995, the comprehensive control measures were carried out for soil-transmitted nematodiasis, and the measures included deworming, health education, safe water, sanitation and environmental remediation. The effects of the comprehensive control measures were evaluated by the investigations of the prevalence of soil-transmitted nematodiasis, awareness of health knowledge, and behaviors of residents. RESULTS: From 1995 to 2012, 646,437 person--times were administrated in deworming medication with 2.48 times per capita; the benefit rate of safe water was 97.90%; the popularity rate of harmless toilets was 86.89%. The awareness rate of health knowledge increased from 54.05% in 1996 to 95.60% in 2012, the difference between them were statistically significant (chi2 = 230.92, P < 0.01); the rate of correct health behaviors increased from 59.07% in 1996 to 96.40% in 2012, the difference between them had statistical significance (chi2 = 202.69, P < 0.01). The prevalence of soil-transmitted nematodiasis decreased from 62.57% in 1989 to 1.21% in 2012, the difference had statistical significance (chi2 = 1016.92, P < 0.01). The infection rates of Ascaris lumbricodes, hookworm and Trichuris trichiura were 0.58%, 1.12% and 0, respectively in 2012, and compared with the rates of those infections in 1989, the decline rates were 94.96%, 97.28% and 100% respectively, the differences between them were statistically significant (chi2 Ascaris = 129.50, chi2 hookworm = 544.62, chi2 Trichurisch = 254.19, all P < 0.01). CONCLUSION: The comprehensive control strategies and measures are effective and soil-transmitted nematodiasis has been controlled in Jinhu County.

[Carbonization of heavy metal Cu implanted sewage sludge and stability of heavy metal in the resulting char].

In this research, a new method for sewage sludge (SS) disposal was introduced, by which heavy metals were implanted into sewage sludge before pyrolysis. Cu was adopted as the representative of heavy metals to test this process and was implanted in the form of CuCl2. Effects of Cu implanting concentration and reaction temperature on the residual ratio and immobilization of heavy metals in pyrolysis char were studied. Meanwhile, two leaching methods were employed with the purpose to determine the maximum capacity of heavy metal immobilization in the char. The primary research results showed that when the Cu implanting concentration was 0.5% (mass fraction), more than 90% of Cu remained in the char after carbonization, and the leachability of heavy metals in the char was related to pyrolysis temperature. Cu leaching from the char increased with increasing pyrolysis temperature. There was also a limitation for Cu implanting concentration in the sewage sludge, which was determined by the destination of the pyrolyzed char. If it went to sanitary landfill, the limitation would be 0.5%. The primary results showed that sewage sludge could be kneaded with other wastes containing heavy metals before pyrolysis to achieve co-processing.

[Influence of ammonia on leaching behaviors of incineration fly ash and its geochemical modeling].

Incineration fly ash could be contaminated with NH3 that was slipped from the ammonia-based selective non-catalytic reduction(SNCR) process and from evaporation of municipal solid wastes' leachate involved in the wastes. This research was conducted to investigate the impacts of ammonia on leaching of dissolved organic carbon (DOC) and metals from incineration fly ash in the pH range of 3.66-12.44 with an active ammonia spike. A geochemical modeling software Visual MINTEQ was adopted to calculate the chemical speciation of metals under the leaching conditions to reveal the mechanism behind the impacts. It was proved that at pH > 9, the leaching of DOC increased significantly in the presence of high concentrations of ammonia (> or = 1 357 mg x L(-1)), but there was little effect when the ammonia level in eluates was not higher than 537 mg x L(-1). At pH < 6, metals in fly ash were released mainly in the form of free metal ions and chloride complexes, which were little influenced by ammonia; while at pH 8-12, higher concentrations of ammonia (> or = 3 253 mg x L(-1)) mobilized Cd, Cu, Ni and Zn significantly due to the formation of soluble metal-ammonia complexes, and the leaching rates reached their peaks at pH around 9; however, ammonia had little impacts on Al and Pb leaching within this pH range. At pH > 12, for Cd, Cu, Ni and Zn, their leaching species were predominantly in the form of hydroxide complexes. Under the ammonia concentration of 3253 mg x L(-1), the Visual MINTEQ modeling results were compared with the experimental data, and it was proved that the leaching of Al, Pb and Zn was mainly controlled by precipitation/dissolution modeling, while Cd, Cu and Ni were controlled by precipitation/dissolution and surface complexation/precipitation processes; Visual MINTEQ modeling could well describe the leaching behaviors of Al, Cu, Pb and Zn from incineration fly ash.

[Kinetic mechanism and characteristics researches for hydrazine-based NOx removal at moderate to high temperatures].

The kinetic mechanism of NOx reduction with hydrazine hydrate in selective non-catalytic reduction (SNCR) process was studied and verified by the experimental results, the dominant radicals and reactions were confirmed through sensitivity analysis and key parameters in SNCR process have been obtained. The results of numerical simulation based on the proposed mechanism showed that the effective temperatures for SNCR de-NOx process were bimodal distribution with the optimum temperatures being 650 degrees C and 975 degrees C respectively and the lower temperature window fell in the range of 597-747 degrees C; while the experimental results proved the bimodal distribution of effective temperature with peak values being 653 degrees C and 968 degrees C respectively and the lower temperature window was within the range of 587-707 degrees C for hydrazine-based SNCR process, Simulation results and experimental results matched well with respect to reaction behaviors versus temperature. Through sensitivity analysis it had been found that the most effective reaction to reduce NO was the decomposition reaction of N2H4 to NH2 and the most helpful radical was NH2. Compared to ammonia the temperature window of hydrazine-based SNCR process on the lower temperature side is more flexible for application. Decreased O2 concentration would move the temperature window to the right side, which was contrary to that of ammonia; while increased n(N2H4)/n(NO) moved the temperature window to the left side and NO, reduction efficiency was also improved. All of these results showed that hydrazine has lower temperature window than those traditional de-NOx reagents and it will be widely used in application of SNCR as a potential reductant for NOx reduction.

[Influence of impurities on waste plastics pyrolysis: products and emissions].

The study is aimed to evaluate the impact of impurities like food waste, paper, textile and especially soil on the pyrolysis of waste plastics. For this purpose, emissions, gas and liquid products from pyrolysis of waste plastics and impurities were studied, as well as the transfer of element N, Cl, S from the substrates to the pyrolysis products. It was found that the presence of food waste would reduce the heat value of pyrolysis oil to 27 MJ/kg and increase the moisture in the liquid products, therefore the food residue should be removed from waste plastics; and the soil, enhance the waste plastics' pyrolysis by improving the quality of gas and oil products. The presence of food residue, textile and paper leaded to higher gas emissions.

Hydrothermal treatment of incineration fly ash for PCDD/Fs decomposition: the effect of iron addition.

The catalytic effect of Fe addition on the decomposition of polychlorinated dibenzo-dioxins and polychlorinated dibenzofurans (PCDD/Fs) contained in municipal solid waste incineration (MSWI) fly ash during the hydrothermal process was investigated. Influencing factors, such as Fe addition mode, reaction time and cooling procedure after reaction, were tested to evaluate their effects. Experimental results indicated that Fe addition in the form of a mixture of ferrous sulphate and ferric sulphate enhanced decomposition of PCDD/Fs contained in the MSWI fly ash, particularly for the decomposition of 2,3,7,8-tetrachlorodibenzo-dioxin and 2,3,7,8-tetrachlorodibenzo-furan under the reaction temperature of 563 K. The decomposition rate of PCDD/Fs reached 90.33% by international toxicity equivalent (I-TEQ) when Fe was added as a mixture of ferrous and ferric sulphates by 5% (wt/wt) with the Fe (III)/Fe (II) ratio being 2; without Fe addition, the decomposition rate of PCDD/Fs was only 46.17% by I-TEQ in the same process. Fe addition in the form of ferrous sulphate alone also showed an enhancing effect on PCDD/Fs decomposition, but the associated decomposition rates were relatively lower, suggesting iron oxides formed from the mixture of ferric and ferrous sulphates are more favourable catalysts. At the same time, the cooling procedure after the hydrothermal reaction became more flexible if Fe was added in the form of a mixture of ferric and ferrous sulphates. Although a longer reaction time was helpful to increase decomposition rates of PCDD/Fs, 1 h was proved to be a reasonable time under this condition.

[Analysis on the target product from sewage sludge pyrolysis and experiments on using the char for enhancing plant cultivation].

Characteristics of sewage sludge pyrolysis under low temperatures were studied and the influences of reaction temperature and moisture content on products distribution and their properties were also investigated with a purpose to select a proper target product. After a dissective comparison, char produced from the pyrolysis process was chosen as the target product and then its effect on plant cultivation was checked by using it to plant garlic when blended into normal soil; also its heavy metals contents and their transfer to the garlic were investigated. The primary research results showed that with the moisture content reduced to a certain level, char production was above 40% of sewage sludge when the pyrolysis process took place under 550 degrees C; ash content of the char is around 60% - 65%, but it is rich with nitrogen, phosphorus and potassium contents. The heavy metal contents in the char meet up with the limitations for land use, and the garlic stems planted in the soil blended with the char grew much faster than those planted in normal soil with their averaged height being 3-4 cm higher; however the heavy metal contents in the fast-growing garlic stems were a little higher than that in the normal ones, which was not suitable for edible plants. The results obtained suggested that char produced from sewage sludge pyrolysis process could be a target product arranged for land use especially for non-edible plant cultivation.

[Study on inhibition of NO(x) and dioxin emissions by carbohydrazide under moderate to high temperatures].

Experimental researches were carried out on the inhibition effects of carbohydrazide (CHZ) on NO(x) and dioxin emissions under moderate to high temperatures, namely De-NO(x) effect of CHZ was investigated in the temperature range of 450-1 050 degrees C with the O2 concentration between 10.1% and 16.7%; and its suppression effect on dioxin emissions was studied both by spraying CHZ solution into incineration flue gases and by mixing CHZ in iron ore in the sintering pot. It was proved that CHZ could reduce NO(x) with dual temperature-linked peaks, i. e. the De-NO(x) efficiency peaks appeared both around 600 degrees C and 967 degrees C, with a vale around 850 degrees C. The results also indicated that CHZ had good suppression effect on dioxin synthesis in the fly ash precipitated in the temperature range of 250-450 degrees C when CHZ solution was sprayed into flue gases at proper temperatures; comparably, for dioxin emissions from the iron ore sintering pot, the more CHZ mixed into iron ore, the less dioxin emissions took place; when the mixture proportion of CHZ (mass fraction) was up to 0.1%, the concentration of PCDD/Fs in TEQ in sintering flue gases was decreased by 78.8% compared to the scenario without CHZ mixing, showing that CHZ is an effective inhibitors for reducing dioxin emissions in the iron ore sintering furnace. All of these results showed that CHZ is a potential inhibitor for dioxin emissions from incinerators and iron ore sintering furnaces as well as a reduction agent for NO(x).