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Vibrofluidized bed drying of citrus processing residue for byproduct recovery.

机译：对柑橘加工残渣进行振动流化床干燥，以回收副产物。

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摘要

Approximately 44% of the citrus that is processed becomes processing residue. The residue consists of the non-juice components of a citrus fruit, primarily peel and pulp, and is recovered by conversion to animal feed. The material is hygroscopic, agglomerating, has a wide particle size distribution, and must be carefully dried to avoid thermal damage to nutrients and flavors. This dissertation evaluates the possibility of utilizing a vibrofluidized bed dryer for citrus processing residue. Results demonstrate that it is possible to overcome the agglomeration difficulties associated with this material, offering an economically viable alternative processing methodology.;To properly analyze this proposed system, a benchtop vibrofluidized bed dryer was designed, constructed and instrumented. Vibrofluidization and batch drying trials were conducted and analyzed. An economic evaluation of the proposed process was undertaken. Two mathematical models of the drying process were developed and validated.;Characteristics that describe the vibrofluidized bed drying of the residue were determined. The conditions that facilitated fluidization were: (1) A particle size distribution of the dried residue that was lognormal, had a geometric mean diameter, dgw, of 3.829 mm, and a geometric standard deviation, Sgw, of 2.49x10-07 mm. (2) A vibrational acceleration, Aω2/g, of 2.54. (3) A minimum vibrofluidization velocity, Umvf, of 4.2 cm/s. The controlling mechanism of the falling rate period was determined to be diffusion, with an effective diffusion coefficient, Deff, of 2.85x10-5 cm/s, and critical moisture content, Mc, of 30%. Economic evaluation of the proposed method has a payback period of 4.34 years, and an estimated processing cost of ;Models were developed based on bed hydrodynamics and three-phase drying kinetics, and thin-layer drying. Both models accurately predicted the drying curves. The three-phase kinetic drying model solved a series of simultaneous equations, and differential equations, based on moisture and enthalpy balances. This complex model successfully predicted the bed hydrodynamic properties and serves to facilitate scale-up, design, and bed configuration investigations. For the thin-layer drying model, the drying constants, K & N, for Page's equation were determined as a function of bed temperature. This computationally simple, single-parameter model would serve process control algorithms.
机译：大约44％的柑橘被加工残渣。残留物由柑橘类水果的非果汁成分组成，主要是果皮和果肉，可通过转化为动物饲料加以回收。该材料具有吸湿性，结块性，粒径分布广泛，必须小心干燥，以免对营养和风味造成热损伤。本论文评估了利用振动流化床干燥器处理柑橘渣的可能性。结果表明，可以克服与这种材料相关的团聚困难，从而提供一种经济可行的替代加工方法。为了正确地分析该提议的系统，设计，构造和安装了台式振动流化床干燥器。进行了振动流化和分批干燥试验并进行了分析。对提议的过程进行了经济评估。建立并验证了干燥过程的两个数学模型。确定了描述残留物经振动流化床干燥的特征。促进流态化的条件是：（1）干燥残渣的粒径分布呈对数正态分布，其几何平均直径d gw 为3.829毫米，几何标准偏差S < sub> gw ，为2.49x10 -07 毫米。 （2）振动加速度Aω 2 / g为2.54。 （3）最小振动流化速度U 为4.2 cm / s。确定下降速率周期的控制机制是扩散，其有效扩散系数D 为2.85x10 -5 cm / s，且临界水分含量为，M c 为30％。该方法的经济评价的投资回收期为4.34年，估计的加工成本为；基于床的流体动力学和三相干燥动力学以及薄层干燥，建立了模型。两种模型都能准确预测干燥曲线。三相动力干燥模型基于水分和焓平衡，解决了一系列联立方程和微分方程。这个复杂的模型成功地预测了床的水动力特性，并有助于进行规模放大，设计和床构造研究。对于薄层干燥模型，佩奇方程式的干燥常数K和N确定为床温的函数。该计算简单的单参数模型将用于过程控制算法。

著录项

  • 作者

    Roe, Eric A.;

  • 作者单位

    University of South Florida.;

  • 授予单位 University of South Florida.;
  • 学科 Agriculture Food Science and Technology.;Engineering Agricultural.;Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 166 p.
  • 总页数 166
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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