THERMAL DEHYDRATION OF THE SODIUM CARBONATE HYDRATES

A thermal gravimetric method was employed to explore the course of dehydration of Na₂CO₃ · 10 H₂O, and Na₃CO₃ · H₂O particles. Experimental data were amassed both in the temperature-increasing and constant temperature mode. Very small sample masses were used in an effort to eliminate an effect of heat and mass transfer processes on the rate of reaction. Kinetic equations of Arrhenius type were proposed for two stages of the dehydration and tested against the results collected by experiment.     

加拿大一枝黄花纤维素合成吸油材料的工艺条件与吸附性能

以加拿大一枝黄花纤维为基材,采用悬浮聚合接枝共聚法制备吸油材料。考察了引发剂过氧化苯甲酰(BPO)用量、交联剂十六烷基三甲基溴化铵(CTAB)用量和甲基丙烯酸甲酯(MMA)与甲基丙烯酸正丁酯(BMA)单体质量比对该产物吸油性能的影响,并通过红外光谱(IR)和扫描电镜(SEM)考察了加拿大一枝黄花接枝前后的性质。结果表明:产物表面附有聚合物,且原材料中的C=O键断裂,产生醚键。这说明加拿大一枝黄花表面已接枝甲基丙烯酸酯。在单体甲基丙烯酸甲酯与甲基丙烯酸正丁酯的质量比为0.75,引发剂BPO质量分数为0.7%和交联剂CTAB质量分数为1.2%的条件下制备吸油材料,其吸附葵花籽废油的性能较好,吸油倍率为21.036 g/g,且重复吸油性能较好。     

高温煤气金属脱硫剂的研究进展

煤的清洁转化利用符合中国的能源结构,高温煤气脱硫是提高能源利用率的关键技术。本文综述了单一金属氧化物和复合金属氧化物干法脱除H2S的研究进展,对比分析了单一金属氧化物在脱硫效率、使用温度和再生方面的优缺点,指出由于单一金属氧化物脱硫剂不能满足实际生产需要,因此兼有单一金属氧化物优点的复合金属脱硫剂成为未来研究方向。同时,论述了复合金属脱硫剂的制备原则、脱硫效率及再生等方面的研究状况。在此基础上,重点对铁酸锌和钛酸锌两种具有代表性的复合脱硫剂及其他复合金属脱硫剂进行了介绍。     

Calcium-based sorbents behaviour during sulphation at oxy-fuel fluidised bed combustion conditions

Sulphur capture by calcium-based sorbents is a process highly dependent on the temperature and CO₂ concentration. In oxy-fuel combustion in fluidised beds (FB), CO₂ concentration in the flue gas may be enriched up to 95%. Under so high CO₂ concentration, different from that in conventional coal combustion with air, the calcination and sulphation behaviour of the sorbent must be defined to determine the optimum operating temperature in the FB combustors.In this work, the SO₂ retention capacity of two different limestones was tested by thermogravimetric analysis at typical oxy-fuel conditions in FB combustors. The effect of the main operating variables affecting calcination and sulphation reactions, like CO₂ and SO₂ concentrations, temperature, and sorbent particle size, was analysed.It was observed a clear difference in the sulphation conversion reached by the sorbent whether the sulphation takes place under indirect or direct sulphation, being much higher under indirect sulphation. But, in spite of this difference, for a given condition and temperature, the CO₂ concentration did not affect to the sulphation conversion, being its major effect to delay the CaCO₃ decomposition to a higher temperature.For the typical operating conditions and sorbent particle sizes used in oxy-fuel FB combustors, the maximum sorbent sulphation conversions were reached at temperatures of about 900 °C. At these conditions, limestone sulphation took place in two steps. The first one was controlled by diffusion through porous system of the particles until pore plugging, and the second controlled by the diffusion through product layer. As a consequence, the maximum sulphation conversion increased with decreasing the particle size and increasing the SO₂ concentration.     

高活性钙基烟气脱硫剂的研究进展

介绍了钙基脱硫剂的原理和使用现状,总结了近年来在通过使用添加剂、掺入粉煤灰和水合作用三方面来改性钙基烟气脱硫剂活性的研究情况,指出提高脱硫剂的比表面积,降低吸收剂的钙硫比,提高钙基烟气脱硫剂的脱硫率和利用率是今后的发展方向。     

CuO/Al203烟气脱硫吸附剂再生技术的研究

对已经硫化的CuO/Al2O3脱硫吸附剂的可再生性进行了实验研究.实验证明,负载型金属氧化铜脱硫吸附剂在硫化后用还原性气体再生是实际可行的;CuO/Al2O3脱硫吸附剂最佳的再生温度为485℃、最佳反应气体流量为2.4L/min、最佳CH4浓度为1.1%.     

“Chemical Heat Accumulators”: A new approach to accumulating low potential heat

The first presentation of new composite Chemical Heat Accumulation materials based on granulated open-porous matrix filled with a hygroscopic substance is given. At storing heat, the materials operate in a reversible hydration/dehydration mode. When crystalline hydrates of simple salts are used as the hygroscopic substance, the new materials allow to reach the heat storing capacity up to 2000 kJ kg⁻¹ even for accumulation of low temperature heat (of circa 20–40°C). The materials also possess improved properties for mass and heat transfer. All these make a serious advantage of these materials in comparison with those using a latent melting-solidification heat as well as with zeolites capable of reversible hydration/dehydration. The new materials can be widely used in energy efficient and freons-less air conditioning devices, for cooling the electronic units, fire-extinguishing and some other applications.     

Treatment of hazardous shipyard wastewater using dolomitic sorbents

Hazardous shipyard wastewater is a worldwide problem, arising from ship repair. In this study an experimental programme was undertaken to establish the suitability of dolomite and dolomitic sorbent materials to remove contaminants from wastewater arising from a commercial shipyard. Experimental data indicate that dolomite and dolomitic sorbents have the ability to significantly reduce the COD concentration of the shipyard effluent (98% reduction). The data gained from trials at a shipyard indicated that the dolomite treatment process could be undertaken in a 8000 L pilot scale reaction vessel. Analysis of the wastewater using ICP-MS during the pilot trial indicated that the dolomite significantly reduced the concentrations of metallic impurities. The concentration of Sn ions, which is indicative of organo-tin complexes commonly found in shipyard wastewater, was reduced by 80% from its initial concentration in the pilot trial. The mechanism for the removal process using dolomite has been ascribed to a metal complexation/sorption process.     

锂基CO2吸附剂在吸附强化甲烷水蒸汽重整制氢中的应用研究进展

简介了吸附强化甲烷水蒸汽重整制氢的研究背景,重点介绍了新型锂基CO2吸附剂(包括Li2ZrO3、Li4SiO4、Na2ZrO3)在吸附强化甲烷水蒸汽重整制氢中的应用研究进展,对新型吸附剂在吸附强化制氢中的应用研究进行了展望。     

Sorptive Removal of Cesium-137 and Strontium-90 from Water by Unconventional Sorbents. I. Usage of Bauxite Wastes (Red Muds)

Bauxite wastes of alumina manufacture, i.e., red muds, have been tested for radiocesium and strontium removal from water. The red muds were water-washed, acid-, and heat-treated before usage to produce hydrous oxide like sorbents. Surface treatment of the sorbent was benefical for ¹³⁷s uptake, while heat-treatment was detrimental to the -SOH surface sites responsible for high ⁹⁰Sr affinity. Fractionation of the sorbent with respect to apparent grain size did not produce significant differences in the sorption efficiency. The distribution coefficients vs. equilibrium activity in solution showed a maximum with Cs, and a gradual decrease trend with Sr. The solution activity vs. adsorption data were fitted to B.E. T. (essentially types IV-V) isotherms for Cs and B.E. T.-Langmuir isotherms for Sr. Desorption, temperature-, pH-, and ionic strength-dependence tests revealed that the primary mode of sorption for both cations is specific adsorption while the secondary mode is ion exchange. A rise in pH favours the ion- exchange sorption of Sr while the specific adsorption of Cs is negatively affected. Competitive adsorption of an inert electrolyte, i.e., NaCl, severely hinders Cs sorption, while Sr sorption on water-washed red mud is not significantly affected.