有机垃圾厌氧发酵过程的生物反应热模型研究

为了考察有机厌氧发酵过程生物热对发酵系统温度的影响,利用微生物生长动力学模型方程式和各组分的物料衡算方程式,建立了有机垃圾厌氧发酵生物反应热的动力学模型,并通过遗传算法对模型部分参数进行了优化。计算结果与文献中的实验值最大相对误差小于2%,表明所建立的生物反应热模型基本可信。本文模型和计算结果可为有机垃圾厌氧发酵过程保温装置的优化设计提供参考依据。

Structural evolution of chars from biomass components pyrolysis in a xenon lamp radiation reactor

The structural evolution of the chars from pyrolysis of biomass components （cellulose, hemicellulose and lignin） in a xenon lamp radiation reactor was investigated. The elemental composition analysis showed that the C content increased at the expense of H and O contents during the chars formation. The values of AH/C/ZSO/c for the formation of cellulose and hemicellulose chars were close to 2, indicating that dehydration was the dominant reaction. Meanwhile, the value was more than 3 for lignin char formation, suggesting that the occurrence of demethoxylation was prevalent. FTIR and XRD analyses further disclosed that the cellulose pyrolysis needed to break down the stable crystal structure prior to the severe depolymerization. As for hemicellulose and lignin pyrolysis, the weak branches and linkages decomposed firstly, followed by the major decomposition. After the devolatilization at the main pyrolysis stage, the three components encountered a slow carbonization process to form condensed aromatic chars. The SEM results showed that the three components underwent different devolatilization behaviors, which induced various surface mornhologies of the chars.

Effect of mixed moderately thermophilic adaptation on leachability and mechanism of high arsenic gold concentrate in an airlift bioreactor

A refractory gold concentrate with 19% arsenic was treated by a mixed moderately thermophiles in an airlift bioreactor through an adaptation protocol. The moderately thermophiles could respond well to 20%(w/v) pulp density with less than 10% loss of productivity, and resist arsenic up to 15 g/L. There were a lot of jarosite, arsenolite and sulfur, but not scorodite and ferric arsenate in the bioleached residue. Jarosite passivation and lower sulfur-oxidizing activity of the cells due to the toxicity of the high concentrations of soluble arsenic and iron ions at low p H value should mainly response for the incomplete extraction at high pulp density. The initial bacterial community did not change in nature except for new found P aeruginosa ANSC, but sulfur-oxidizing microorganisms have been dominant microorganisms after a long time of adaptation. Pseudomonas aeruginosa originating from the gold concentrate should be closely relative to the metabolism of the organic matters contained in the refractory gold concentrate.

Maximum Hydrogen Production by Autothermal Steam Reforming of Bio-oil With NiCuZnAI Catalyst

Autothermal steam reforming （ATR） of bio-oil, which couples the endothermic steam reform- ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effective production of hydrogen through ATR of bio-oil was performed at lower temperature with NiCuZnAl catalyst. The highest hydrogen yield from bio-oil reached 64.3% with a nearly complete bio-oil conversion at 600℃, the ratio of steam to carbon fed （S/C） of 3 and the oxygen to carbon ratio （O/C） of 0.34. The reaction conditions in ATR including temperature, O/C, S/C and weight hourly space velocity can be used to control both hydrogen yield and products distribution. The comparison between the ATR and common steam reforming of bio-oil was studied. The mechanism of the ATR of bio-oil was also discussed.

DNA-assisted rational design of BaF_2 linear and erythrocyteshaped nanocrystals

The synthesis of inorganic materials with special morphologies with the assistance of biological molecules is a potential development in the field of controllable growth and assembly of nanomaterials. In this paper, BaF2 nanocrystals in patterns of well-defined linear and erythrocyte-shaped structure were synthesized with the assistance of Escherichia coil DNA. Morphology and the arrangement of BaF2 particles on DNA were controllable by altering the reaction condition. Square nanoparticles arranged in linear chains were gained with the assistance of normal DNA; while, erythrocyte-shaped BaF2 nanospheres were synthesized with the assistance of denatured DNA. Besides, the influences of solvent, reaction temperature, concentration of reactants and the heating time on the morphology of the BaF2 particles were studied.

A Comparative Study on the Fixed Bed Pyrolysis of Different Biomass Solid Wastes

Biomass in the form of nutshell, hay of catkin, wheat straw and linseed residue in particles have been pyrolyzed in laboratory scale fixed bed reactor which yielded liquid oil, solid char and gas. The variation of oil yield for different biomass feedstock with reactor bed temperature and feed size is presented in this paper. A maximum liquid yield of 55 wt% of dry feedstock is obtained at an optimum temperature of 500℃ for a feed size of 300-600μm with a running time of 55 min for nutshell as the feedstock while the minimum liquid oil yield is found to be 30 wt% of feedstock at an optimum temperature of 400℃ for a feed size of 2.36 mm with a running time of 65 min for linseed residue as the feedstock. A comparison on the product yields is highlighted in this study. The pyrolysis liquid products are characterized and compared for some of the fuel properties like HHV （higher heating value）, viscosity, density and specific gravity.

Torrefied Pellets as Fuel for Two-Stage Technology of Biomass Conversion into Synthesis Gas

One of the most important properties of the torrefied pellets, along with high calorific value, is their hydrophobicity. Inability to absorb moisture and self-destruct under its influence determine possibility of using of pellets in the pyrolysis reactor. For the technology of two-stage thermal processing of biomass, developed at the Joint Institute for High Temperatures, the amount of synthesis gas which can be obtained from one kilogram of torrefied pellets is also important. A construction of the pilot torrefaction reactor powered by flue gas is shown. The results of experimental investigations of hydrophobicity of torrefied pellets produced by the reactor and quantity of synthesis gas which can be obtained by two-stage thermal processing of the pellets are presented. It is shown that torrefaction allows simplifying the process of conversion of pellets into synthesis gas without significant reduction in the volume of the gas.