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最低喷动速度是喷动床设计的重要参数之一。过去人们习惯采用Mathur-Gisher公式来计算,但由于该公式是建立在小直径床层(D_c=0.076~0.3m)实验的基础上的,故在大直径床层上应用时,产生明显的偏差。本文通过实际数据分析,提出了大直径喷动床层最低喷动速度计算的经验公式。 相似文献
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惰性粒子喷动床中反应干燥集成化制备超细碳酸钙 总被引:1,自引:0,他引:1
在一内径为42mm的惰性粒子喷动床中, 以CO2气体和Ca(OH)2悬浮液制备超细碳酸钙粒子为研究对象,实验考察了进气中CO2气体浓度、Ca(OH)2悬浮液浓度、反应温度,静床高等操作条件对产物制备的影响。结果表明,利用惰性粒子喷动床反应与干燥集成化的特点,获得了平均粒度为80 nm、含水量低于0.15%的方解石型超细碳酸钙粒子,开发了一步法制备超细碳酸钙的新工艺。 相似文献
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煤焦与CO2的气化反应是评价煤种气化反应活性的重要指标之一.分别在自主设计的一套微型喷动床反应装置和热重分析仪上采用等温和非等温的方法对煤焦-CO2气化反应动力学进行探讨.结果表明:神华焦和大雁焦CO2气化反应符合混合反应模型,其采用非等温分析方法由Coats-Redfern近似函数和Doyle近似函数得到的反应活化能... 相似文献
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1前言在普通喷动床的环形区底部额外引入一股辅助气体,由于喷动气体和辅助气体各自独立地改变,气固系统将出现下列几种体系或操作状态:①固定床;②充气喷动床;③喷流床;④带射流的流化床。长期以来对充气喷动床与喷流床的区别不是很清楚的[1~5]。张怀清等[6... 相似文献
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狭缝式矩形喷动床中多粒度颗粒体系的最大喷动压降 总被引:2,自引:0,他引:2
在 15 0 mm× 5 0 mm× 110 0 mm的矩形喷动床中 ,研究了单一粒径体系和二组分及三组分混合粒径颗粒体系的最大喷动压降受颗粒粒径及粒度组成、静止床高和气体入口狭缝宽度的影响情况。实验采用宽度为2、4、6 mm三种宽度的狭缝式气体分布板 ,实验物料为单一粒径分别为 1、1.5、2 mm的玻璃珠。实验表明矩形喷动床的最大喷动压降与上述三种影响因素都有关系。本文还给出了最大喷动压降随这三种因素变化的实验关联式 相似文献
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ABSTRACT This paper presents an axisymmetric three-dimensional semi-empirical model that describes the airflow in both the spout and annular regions. Both the pressure and air velocity distributions can be calculated at any point inside the dryer. Thus, the effect of the fluid dynamics on the heat and mass transfer coefficients and, consequently, on the drying process, can be evaluated. The finite element method was used to solve the model. Pressure distributions were measured for several conditions in which stable spouted bed flow regime was attained. Simulated pressure distributions agreed well with experimental data. 相似文献
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在实验滴流床反应器内用含23%Cu,17%Cr的氧化铝催化剂进行过氧化氢的等温分解,以测试不同操作条件下液相色反应物围化率空时的依赖关系。实验证实对氧化氢分解是一个液相反应物起限制性作用的1级反应,模型预测与实验数据的比较表明:除催化剂效率因子以外,必须考虑外部质量传递和催化剂不完全润湿的影响,Dudkovic提出考虑催化剂总效率因子的近似模型完全能够模拟上述2种影响。 相似文献
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From the successful drying of paddy in a lab-scale triangular spouted bed (TSB), a pilot scale unit with a capacity of 500kg/batch was constructed and used to dry paddy of high moisture contents. The drying tests showed that air temperatures of up to 160°C in the first stage, followed by a lower temperature of 80-100°C in the second stage, can be used to dry paddy from more than 25% down to around 15% (w.b.) without significantly changing grain quality in terms of head rice recovery. Moisture distribution in the pilot-scale TSB was observed to be satisfactorily uniform. 相似文献
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R.S. Concei o Filho M.A.S. Barrozo J.R. Limaverde C.H. Ataí de 《Drying Technology》1998,16(9):2049-2064
Soybean seeds were coated with fertilizer by the atomization of a fertilizer suspension using a spouted bed. The efficiency of coating adhesion was measured as the coating mass adhering to the seeds and the sprayed solids mass. The change in moisture mass between coated and uncoated seeds was considered in the evaluation of yield. A study of binder concentration and process time was conducted in order to discover conditions under which germination of coated seeds was feasible. Final experiments were done in order to quantify the influences of spouted bed air temperature and fertilizer suspension flowrate on the process yields and the germination capacity of coated seeds. Two empirical equations resulted from the use of Myers' surface technique (1976). These equations predict yield and germination for the range of variables studied. 相似文献
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R.S. Conceição Filho M.A.S. Barrozo J.R. Limaverde C.H. Ataíde 《Drying Technology》2013,31(9-10):2049-2064
ABSTRACT Soybean seeds were coated with fertilizer by the atomization of a fertilizer suspension using a spouted bed. The efficiency of coating adhesion was measured as the coating mass adhering to the seeds and the sprayed solids mass. The change in moisture mass between coated and uncoated seeds was considered in the evaluation of yield. A study of binder concentration and process time was conducted in order to discover conditions under which germination of coated seeds was feasible. Final experiments were done in order to quantify the influences of spouted bed air temperature and fertilizer suspension flowrate on the process yields and the germination capacity of coated seeds. Two empirical equations resulted from the use of Myers' surface technique (1976). These equations predict yield and germination for the range of variables studied. 相似文献
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Sachin Y. Chinnapa Reddy Ashok N. Bhaskarwar 《Chemical Engineering Communications》2000,178(1):103-127
A model to predict conversions in a froth bed reactor has been developed. The model is then compared against the available experimental data on the oxidation of sodium sulfide in a foam bed contactor. The predictions using the present model are also compared against those based on the model of a foam bed reactor developed earlier. The predictions using the present model agree fairly well with the experimental data and, in some cases, are even in better quantitative agreement than the previous single stage model of a foam bed reactor. The case of significant surface resistance due to surfactant has also been analyzed theoretically, obtaining analytical solutions for the concentration profile and fractional gas absorption in a liquid froth shell. 相似文献
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喷动床环隙区内颗粒流的数学模型和仿真 总被引:3,自引:0,他引:3
Solids motion in the annulus of a spouted bed can be considered as a quasi-static deforming flow similar to that in a silo. Several simplified granular-flow models by Sullivan et al. including kinematic, potential and plastic theory, are investigated in this paper. The model of solids circulation by Morgan et al is combined with the above granular models to predict solids axial velocity in annulus. The finite element method is adopted and the complicated spout-annulus shape geometry is especially considered. Simulated results are compared with experimental data from He et al. It indicates that kinematic theory agrees well with experiments. The regressed kinematic constant B for annulus flow is greatly larger than that for silo flow. Potential theory obtains similar result with kinematic theory, but is incomplete in its physical significance. Plastic theory gives unrealistically oscillatory solution because of the over simplification of stress field. Finally, the Euler equations coupling the momentum transfer of solids with the frictional stress field are proposed for future study. 相似文献
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Ultra-fine powders are difficult to be fluidized due to the strong particle to particle cohesiveness.However, the authors‘ experiments showed that the ultra-fine powder CaCO3 could be stably fluidized in a spouted bed with a draft tube. The effects of geometric and operating parameters on solid circulation rate of ultra-fine powder CaCO3 were investigated in a 120 mm diameter transparent semicircular spouted bed with a draft tube. Three draft tubes with different sizes were used in this study. It was found that the solids circulation rate was mainly dependent on the drawing rate of the gas jet from the nozzle, then on the gas transport capacity in the draft tube. With increasing gas feed rate, distance between the nozzle and the draft tube inlet and draft tube diameter, the solids circulation rate could be increased. Based on the jet theory, a quantitative correlation was proposed for predicting the solid circulation rate of ultra-fine powders in a spouted bed with a draft tube by taking into account the gas transport capacity in the draft tube. 相似文献