磁性壳聚糖微球固定化酵母细胞及其用于发酵生产酒精的研究

通过溶胀一吸附法用磁性壳聚糖微球固定化酵母细胞,考察了磁性壳聚糖微球固定化酵母细胞的效果.结果表明,大量酵母细胞被固定在磁性微球表面,且磁性壳聚糖微球可重复使用.以所制备的磁性固定化酵母细胞发酵生产酒精,发酵醪液的酒精度高于悬浮酵母细胞发酵醪液的酒精度,重复使用磁性壳聚糖微球固定化酵母细胞再次发酵,醪液的酒精度虽然有所下降,但是仍高于悬浮酵母细胞发酵的酒精度.     

糖化醪酵母连续发酵生产酒精的研究

本文对淀粉质原料的糖化醪的固定化酵母连续发酵生产酒精和以糖化醪配制增殖液增殖固定化K字酵母,进行了研究和讨论,确定了较佳的工艺条件,得到了良好的结果。     

生物质和惰性颗粒二组分混合物的最小流化速度

实验发现纯锯末不能在流化床中流化，锯末中加入惰性固体颗粒构成锯末／玻璃珠、锯末／沙子双组分混合物可实现流化．研究了不同粒径、不同配比混合物的流化规律．已有的预测双组分混合物最小流化速度的公式不能应用于锯末／玻璃珠、锯末／沙子双组分混合物．同时研究了球形、椭圆形菜籽的最小流化速度，并研究了不同粒径菜籽与不同粒径沙子在不同比例下的最小流化速度，结果表明形状规则生物质／惰性颗粒混合物最小流化速度可由Ｃｈｉｂａ公式计算     

以玉米为原料的乙醇发酵工艺优化

以糖化醪液及发酵醪液为研究对象,通过响应面实验对ρ(糖)、营养成分及发酵工艺进行优化,达到提高酵母活性,实现高ρ(乙醇)发酵技术的突破。利用Placket-Burman(PB)实验证明磷酸氢二铵对乙醇发酵有促进作用,而磷酸氢二钾和硫酸钾对乙醇发酵无显著促进作用。利用响应面实验对ρ(糖化醪糖)及ρ(磷酸氢二铵)进行优化,当发酵醪与高质量浓度糖化醪[ρ(葡萄糖)=316 g/L]按体积比1∶1混合后,补加2 g/L磷酸氢二铵,并在30℃条件下发酵48 h,实现醪液ρ(乙醇)=137 g/L[φ(乙醇)=17%],醪液ρ(葡萄糖)1.7 g/L。     

PVC类废塑料在冷态流化床中流化行为的研究

在Φ50 mm×800 mm圆柱体的冷态流化床反应器中,对PVC类废塑料、石英砂及其混合物的流化特性进行了研究。研究了PVC颗粒粒径与混合物料中PVC质量分数对混合物料的流化特性的影响规律,得到指导热态实验的关键参数。实验结果表明,PVC颗粒粒径与混合物料中PVC质量分数会影响混合物料的最小流化速度,也影响PVC颗粒与石英砂混合的均匀度。混合物料中PVC的质量分数越小,其最小流化速度就越小,混合物料也越容易实现充分混合;PVC颗粒为Geldart B类颗粒,但由于形状不规则,黏性力大,塌落特性明显,流化性能较差,显示出C类颗粒的流化特性,同时实际的最小流化速度要大于理论最小流化速度。PVC与石英砂混合物料冷态流化行为的研究结果为热态流化床降解PVC颗粒提供了基础数据和实践依据。     

生物质和惰性颗粒二级分混合物的最小流化速度

实验发现纯锯末不能在流化床中流化，锯末中加入惰性固体颗粒构成锯末／玻璃珠、锯末／沙子双组分混合物可实现流化。研究了不同粒径、不同配要比混合物的流化规律。已有的预测双组分混合物最小流化速度的公式不能应用于锯末／玻璃珠／锯末／沙子双组分混合物。     

废醪液的絮凝过滤

一、引言在微生物发酵法生产丙酮、丁醇过程中有大量的废醪液排出。其中含有一定的有饲用价值的营养物质。其组成列于下表。长期以来,国内生产厂的废醪液,只有少量直接用作饲料或肥料。国外主要是将废醪液蒸干,作饲料添加剂。但蒸发干燥耗能较高。     

脉动流化干燥过程的实验研究

将热气体引入流化床，对流化床中的矩形波脉动干燥过程进行了实验研究。实验中使用了小米和硅胶两种物料，考察了物料湿含量及床层温度变化情况，并将脉动流化干燥与无脉动流化干燥效果进行比较，发现小米在一定的脉动条件下能够节能，而硅胶的节能效果不明显。文章还对气流脉动流化干燥的应用和进一步研究方向进行了分析和展望。     

我愿化身为一个酵母——记天冠集团乙醇公司乙醇厂工艺工程师赵朋

＂我愿化身为一个酵母,随着流动的醪液去探索神秘的发酵机理＂,在一次技术创新表彰会上,赵朋的话,打动了在场所有的人。酵母究竟有着怎样的魔力,会让赵朋为之倾倒,如此痴迷？     

振动流化干燥技术

一、振动流化干燥的特点 振动流化干燥是在一般流化干燥的基础上附加振动作用,来处理一般流化干燥难以处理的易粘结、易团聚物料的待殊干燥方式,它与一般流化干燥相比,具有很多突出的优点:     

Internally circulating fluidized bed for continuous adsorption and desorption

An internally circulating fluidized bed has been developed for continuous adsorption and desorption. This system can be used more generally for many other reaction/regeneration operations. It helps to separate and to recover gaseous pollutants and reusable compounds (e.g. CO₂, SO₂, organic solvent vapors, along with other gases). Two fluidized beds are arranged next to each other. The partition wall in the upper and lower part of the fluidized beds has horizontal openings to let solid matter pass through. As the two beds are fluidized at different rates, the bed material starts to circulate between the two beds. The bed material doubles as an adsorbent. In the adsorption zone, polluted gas is used for fluidization; in the desorption zone, heated air or steam is used. The main differences from conventional fixed-bed adsorbers are that plants can be built in a more compact manner, higher flow rates can be achieved, and separate optimization of the two zones (adsorption zone, desorption zone) is possible.     

离心流化床初始流化状态的研究(Ⅱ)实验研究

对离心流化床初始流化状态进行了实验研究。结果表明,下行程床层压降流速曲线的规律一致,流化时床层压降趋于稳定;上行程曲线受床体结构、物料装填方式和运行状况的影响很大。实验测定初始流化速度应采用下行程曲线。可视性实验证实了离心流化床逐层初始流化,已流化部分的床层物料充分混合。     

Flow patterns and mass transfer rates in fluidized bed ion exchange equipment

The axial mixing of ion exchange resin and liquid in fluidized beds is modelled by a series of well-mixed cells for the resin and an equal or larger number of mixed cells for the liquid. Concentration breakthrough curves are calculated using this mixing model, assuming finite mass transfer kinetics and irreversible equilibrium. The model is used to describe mixing patterns and kinetics in static fluidized beds (no resin flow); the information so obtained can be used to design continuous and periodic flow counter-current fluidized bed ion exchange systems.     

The uses of magnetic fields in the processing of solids

This paper shows how properly applied magnetic fields can advantageously be used to control the behavior of streams of solids which contain some magnetizable material. In particular, we describe the development of a new magnetic flow meter for solids, a quick acting on-off valve with no mechanical action, a sliding solids reactor which may be used for particle filtration and related operations, a positively controlled multistage moving bed contactor, fluidized beds with no gross bubbling or gas bypassing, and especially, a reliably operating distributor-downcomer for fluidized beds.The prospects are considered that these devices may open the way to new types of gas/solids contactors including non-plugging trouble-free multistage fluidized beds.     

Some Drying Aspects of Multistage Fluidized Beds

Multistage fluidized beds with and without downcomers to the horizontal perforated plates are used to dry food materials under different experimental conditions. The influence of various operating parameters such as inlet temperature of the heating medium, flow rate of the heating medium, material flow rate, and number of stages have been investigated. The performance of multistage fluidized beds with and without downcomers is compared and the difference in performance is explained based on stagnancy and short-circuiting of materials in each stage.     

Modelling turbulent fluidized bed reactors: tracer and fibre optic probe studies

Phenomenological models for turbulent fluidized beds are presented in this study. These models are based on a “core-annulus” representation of the turbulent fluidized bed.Three flow regions are considered: (1) gas flows through a dense annular region and is either perfectly mixed or in plug flow; (2) gas circulates in the core as bubbles in plug flow; (3) gas is perfectly mixed in a dense emulsion phase, also in the core zone. The models also account for mass transfer between different regions by assuming various possible gas exchange paths.A new technique which combines novel reflective fibre optic probes and statistical signal treatment is used to measure local flow properties. Results from fibre optic experiments coupled with those from an inert non-adsorbing tracer (helium) allow for mass transfer parameter assessment.These data demonstrate the importance of incorporating an annular region in the simulation of the main bed section of turbulent fluidized beds. Modelling results of this work strongly suggest the critical importance of gas exchange between bubbles in the core and a pseudo-homogeneous annular region.     

Mass transfer in liquid-fluidized and spouted beds of ion exchange resin at low Reynolds number

Rates of mass transfer from the liquid phase to small ion exchange resin particles (0.78 mm in mean diameter) in fluidized and spouted beds were studied experimentally. Dilute aqueous solution of sodium hydroxide was fed into the beds of strong cation exchange resin and the exit concentration of the solution was determined by conductivity measurement. In spouted beds, the initial conversion and K_l increased with bed height, but decreased with fluid flowrate. The model, applying material balance of the reactant and axisymmetric flow of fluid in the annulus of a spouted bed, predictions of the initial conversion in spouted beds are satisfactory. In fluidized beds, the obtained mass transfer coefficients were correlated and compared with other works.     

APPLICATIONS OF CROSSFLOW MAGNETICALLY STABILIZED FLUIDIZED BEDS

The utilization of fluidized beds to effect separations has been limited by the fluid bypassing and particle mixing which tends to decrease the efficiency of separation. Application of a magnetic field to a fluidized bed of magnetizable particles produces a quiescent state with several of the best properties of both fluidized and fixed beds. Similar to fluidized beds, the magnetized beds resemble a liquid and are easily transported between vessels. Their contacting properties, however, are close to those of packed beds with near plug flow of both the fluid and bed particles. These magnetized fluidized beds have advantages when operated in a crossflow configuration, with continuous participates movement transverse to the ascending flow of the fluidizing fluid. Applications of these crossflow beds include solids/solids separation, fluid filtering, and chromatographic separations.     

Particle flow behavior in three-phase fluidized beds

Non-uniform flow behavior of fluidized solid particles in three-phase fluidized beds has been analyzed by adopting the stochastic method. More specifically, pressure fluctuation signals from three-phase fluidized beds (0.152 m ID x 2.5 m in height) have been analyzed by resorting to fractal and spectral analysis. Effects of gas flow rate (0.01-0.07 m/s), liquid flow rate (0.06-0.18 m/s) and particle size (0.001-0.006 m) on the characteristics of the Hurst exponent, spectral exponent and Shannon entropy of pressure fluctuations have been investigated. The Hurst exponent and spectral exponent of pressure fluctuations attained their local maxima with the variation of liquid flow rate. The Shannon entropy of pressure fluctuation data, however, attained its local minima with the variation of liquid flow rate. The flow transition of fluidized solid particles was detected conveniently by means of the variations of the Hurst exponent, spectral exponent and Shannon entropy of pressure fluctuations in the beds. The flow behavior resulting from multiphase contact in three-phase fluidized beds appeared to be persistent and can be characterized as a higher order deterministic chaos.     

Flow characteristics in packed and fluidized rotating beds

Free particles in a rotating tapered cylindrical container are, as a consequence of the circular motion, forced radially outwards towards the circumference to form a packed annular bed. If the container wall is porous and a fluid is allowed to flow radially inward, the bed material may become fluidized. In the resultant centrifugal fluidized bed, radial accelerations many times one g can be generated, permitting much larger fluid flow rates during fluidization than are possible with a conventional fluidized bed. Entrainment of material can also be greatly reduced in such a geometry.The flow in both packed and fluidized beds in a rotating system is analyzed. Expressions are found for the shape of the bed as well as the distribution of particles in packed beds containing mixtures of materials having different size distributions and densities. Based on these results, equations predicting the pressure drop and radial flow distribution are deduced. The condition and location where initial fluidization of the packed bed occurs are predicted. Similarly, conditions in the fluidized state are analyzed, and it is shown that the tangential velocity distribution in the bed under these conditions is directly proportional to the bed radius.Experiments confirming the validity of the analytic models are conducted over a range of operating conditions for different bed materials.