Multi-stage biomass gasification in Internally Circulating Fluidized-bed Gasifier (ICFG): Test operation of animal-waste-derived biomass and parametric investigation at low temperature

In this study, the design, construction and operation of an Internally Circulating Fluidized-bed Gasifier (ICFG) are introduced in detail. ICFG design provides a multi-stage gasification process, with bed material acting as the medium for char combustion and heat exchange by its internal circulation. And it is used for the steam gasification of animal waste at low temperature in view of producing fuel gas. The effects of pressure balance, pyrolysis temperature, catalytic temperature and steam/feedstock ratio on the gasifier performance (e.g. product gas yield, gas composition, tar content) are also discussed. Hydrogen-rich and low-tar product gas can be produced from the low-calorific feedstock, in the properly designed process together with high-performance catalyst.     

提高流化床中铁矿粉还原反应速度的研究(Ⅰ)

为探索提高还原反应速度和防止粘结可能的新途径,研究了以流化床还原尾气先对矿粉进行附着碳处理并预热,再进行流态化还原的过程,并运用极差分析方法考察了影响还原速度和粘结的因素主次顺序。实验表明,用矿粉预附着碳后再还原和提高还原压力、还原气线速的方法,能使流化床中铁矿粉的还原速度大大增快并防止粘结,矿粉附着碳量5%,达70%还原度所需的时间仅为8分钟,比不采取附着碳工序的还原时间缩短20分钟左右。影响还原速度和粘结的主要因素分别是矿粉附着碳量和还原温度。     

流化床夹带颗粒浓度轴向分布的研究

继φ500mm 流化床中的夹带研究之后,本工作在φ154mm 有机玻璃流化床中实验研究了 FCC 催化剂,DX 型苯酐催化剂和丙烯腈催化剂在稀相区夹带颗粒浓度的轴向分布规律。在 TPH 概念和前人工作的基础上,本工作提出了一修正夹带模型和“恒夹带出口高度”CEOH 的概念,并获得了多种条件下的稀相区颗粒浓度的统一关联式。     

流化床中吸附干燥大豆特性研究

在流化状态下种子（大豆）与硅胶能够很好的混合，通过湿含量梯度进行传质，干燥后种子质量显著提高；种子与硅胶粒径不同，便于分离。通过实验比较了在不同混合比和不同流化条件下种子的干燥特性。随着吸附剂的加入，干燥速率明显增大，并且随着风速的提高、硅胶与种子混合比的增大，干燥速率也随之提高。通过试验还表明，采取流化床与固定床动静结合的吸附干燥方式，在节能和产品质量方面有一定的优势。     

Semi-continuous hydrogen production from catalytic methane decomposition using a fluidized-bed reactor

Non-oxidative, catalytic decomposition of hydrocarbons is an alternative, one-step process to produce pure hydrogen with no production of carbon oxides or higher hydrocarbons. Carbon produced from the decomposition reaction, in the form of potentially valuable carbon nanotubes, remains anchored to the active catalyst sites in a fixed bed. To facilitate periodical removal of this carbon from the reactor and to make hydrogen production continuous, a fluidized-bed reactor was envisioned. The hypothesis that the tumbling and inter-particle collisions of bed material would efficiently separate nanotubes anchored to the active catalyst sites of the bed particles was tested and shown to be invalid. However, a switching mode reaction system for the semi-continuous production of hydrogen and carbon nanotubes by periodic removal and replenishment of the catalytic bed material has been successfully demonstrated.     

Evaluation of oxygen uncoupling characteristics of oxygen carrier using micro-fluidized bed thermogravimetric analysis

Oxygen uncoupling characteristics of a natural manganese ore and a perovskite-type oxide CaMn0.5Ti0.375Fe0.125O3 were studied by using a microfluidized bed thermogravimetric analysis (MFB-TGA) technology which is based on a real-time mass measurement of fluidizing particles inside a bubbling bed reactor. The chemical stability, kinetics of the oxygen release and uptake reactions and flu-idization property were investigated and the experimental data measured by MFB-TGA were compared with the results in a regular TGA instrument (TGA Q500). The regular TGA Q500 results show the reac-tivity of both the manganese ore and perovskite oxide are stable for multi cycles, and the oxygen uncou-pling capacity of the manganese ore is～1.2％(mass) which is～2 times higher than that of the perovskite oxide. However, the experimental results from the MFB-TGA indicated that there is a serious agglomer-ation for the manganese ore. A very important finding is that the reaction rate of oxygen release and oxy-gen uptake of the perovskite oxide measured by the MFB-TGA are ～2 and ～4 times faster than that of testedby the TGA Q500. We can conclude that MFB-TGA is a very useful tool to measure the reactivity stability and kinetics of oxygen carriers in high-throughput analysis instead of the regular TGA.     

Reuse of bottom ash and fly ash from mechanical-bed and fluidized-bed municipal incinerators in manufacturing lightweight aggregates

This study involved the reuse of residues, including fly ash (FA) and bottom ash (BA), from municipal solid waste (MSW) incineration and reservoir sediment (RS) to make lightweight aggregates (LWAs) and to evaluate the effects of the incinerator type, material mixing ratio, and preparation conditions on the properties of the resulting aggregates. The MSW incineration ashes were mixed in three different ratios (65% BA + 15% FA, 70% BA + 10% FA, and 75% BA + 5% FA) with reservoir sediment and were sintered at temperatures of 950–1050?°C. The ash samples were obtained from an incineration plant equipped with fluidized-bed (FB) and mechanical-bed (MB) furnaces. The ash from the FB incinerator could be turned into LWAs at a relatively low temperature (1000?°C). Compressive strength measurements indicated that these aggregates were stronger than those manufactured using the ash from the MB incinerator. The BA and FA from the FB incinerator showed good chemical stabilities due to the operating conditions of the incinerator, suggesting that they are suitable for fabricating LWAs. Thus, the thermal synthesis of LWAs from mixtures of incineration residue and RS is a highly effective method for the recycling/disposal of MSW incinerator ash.     

Multi-objective optimization of an industrial fluidized-bed catalytic cracking unit (FCCU) using genetic algorithm (GA) with the jumping genes operator

The multi-objective optimization of industrial operations using genetic algorithm and its variants, often requires inordinately large amounts of computational (CPU) time. Any adaptation to speed up the solution procedure is, thus, desirable. An adaptation is developed in this study that is inspired from natural genetics. It is based on the concept of jumping genes (JG; transposons). The binary-coded elitist non-dominated sorting genetic algorithm (NSGA-II) is adapted, and the new code, NSGA-II-JG, is used to obtain solutions for the multi-objective optimization of an industrial fluidized-bed catalytic cracking unit (FCCU). This unit is associated with a complex model that is highly compute-intense. The CPU time required for this problem is found to reduce fivefold when NSGA-II-JG is used, as compared to when NSGA-II is used. Solutions of similar two-objective optimization problems for the FCCU are compared. NSGA-II-JG also gives improved convergence characteristics and spread of the optimal Pareto points for two simpler multi-objective optimization problems studied here. Indeed, in one problem, where several optimal Pareto fronts exist, the new code gives the correct, global optimal Pareto set, while the original code (binary-coded NSGA-II) converges to local Paretos. The JG operator is associated with some kind of macro–macro-mutation and introduces higher exploratory capabilities, counteracting the effect of elitism in NSGA-II. We, thus, have a better algorithm incorporating the advantages of elitism. This adaptation can prove to be of considerable value for solving other compute-intense problems in chemical engineering.     

新式流化床在PVC树脂干燥上的应用

介绍了株洲化工厂从日本引进的单级内热式流化床干燥工艺和设备参数，对不同干燥方法的优、缺点作了比较，并对内热式流化床为什么节能效果显著作了对比分析。     

Nitrate removal characteristics of high performance fluidized-bed biofilm reactors

Two laboratory-scale high performance fluidized bed biofilm reactors (FBBR) with sand as the biofilm carrier were used to investigate the denitrification of high-strength nitrate wastewater with specific emphasis on the effect the nitrogen loading rate and the superficial velocity (V(s)). The results demonstrated that the FBBR system is capable of efficiently handling an exceptionally high nitrate nitrogen concentration of 1000 mg N/L. At a loading rate of 6.3 kg-N/m(3)(bed).d almost complete denitrification was achieved with a removal efficiency of 99.8% and an effluent concentration of 2mg N/L at V(s) values of 45, 55 and 65 m/h. The maximum efficient loading rate (R(max)) at which the US drinking water nitrate-nitrogen standard concentration of 10mg N/L would be exceeded was found to be a function of the applied V(s). The R(max) was found to be 12 kg-N/m(3)(bed).d at a V(s) value of 45 m/h. As V(s) was increased to 55 and 65 m/h, the optimum R(max) dropped to 9.5 and 8 kg-N/m(3)(bed).d, respectively. Higher denitrification rates were achieved at relatively lower V(s). However, there is a minimum practical velocity below which agglomeration of biomass would occur. The suspended solids concentration in the effluent was below 30 mg/L throughout the study.