Dense phase pneumatic transport of

Dense phase pneumatic transport of bulk materials has become an important technology in many industries: from pharmaceuticals to petro-chemicals and power generation.
This is due to the increasing demands for product quality, and of environmental legislation. Much current industrial interest centers on a particular mode of dense phase transport called ‘plug flow’. This type of low velocity pneumatic conveying has been quoted as causing less particle attrition, reduced component wear, and lower energy costs. For these reasons, plug flow systems are widely applied in many modern industrial applications. [1] The discrete element method (DEM), sometimes called the distinct element method, is becoming widely used in simulating granular flows. Pioneering work in the application of the method to granular systems was carried out by Cundall and Strack(1979) [2]. Also they developed the program BALL to simulate assemblies of discs. Early work concentrated on the use of ‘springs and dashpots’ to represent particle interactions. Y.Tsuji [3] [4] further developed and modified Cundall and Strack’s model, where DEM was first employed in simulation of a plug flow system. The Ergun equation was applied to give the fluid force acting on particles in a moving or stationary bed. The wave-like motion of the flow boundary was observed clearly in that simulation. And good agreement was obtained for the relation between the height of the stationary deposited layer and the plug flow velocity. But due to the limitation of computation time, the author only considered the large particles (d > 10 mm), and simulated a short pipe with only 1000 particles. Quantitative disagreement was observed in the results. To make the calculation to be more realistic, the present authors consider smaller particles (d=3 mm), longer pipe (L=8 m) and simulate more than 40000 particles. A nonlinear spring and dashpot model has been employed in the present work combined with finite difference method and SIMPLE method (Semi-Implicit Method for Pressure- Linked Equation).

結果 (中文) 1:

密相气力输送的散装材料已成为一项重要的技术，在很多行业： 从药品到石油化工和发电。这是因为不断增长的需求，为产品质量和环境立法。关注当前的工业中心运输称为 '塞流' 的密相的特定模式。这种类型的低流速气力输送已引述了造成少颗粒自然减员、 减少的组件磨损和降低能源成本。基于这些原因，塞的流系统广泛应用于许多现代的工业应用。[1] 离散单元法 （DEM），有时被称为离散元方法，成为广泛应用于模拟颗粒流。由 Cundall 和 Strack(1979) [2] 进行开创性研究方法对颗粒系统的应用。此外他们开发的程序球来模拟程序集的光盘。早期的工作集中在 '弹簧和阻尼器' 的使用来表示粒子的相互作用。Y.Tsuji [3] [4]，进一步开发和修改 Cundall 和特拉的模型，DEM 第一次从事插头流系统的仿真。额尔古纳方程给移动的或静止的床内颗粒的流体力。在这个模拟可明显观察流边界的波状运动。好协议制得的固定高度之间的关系为沉积层和插头流速。但由于计算时间所限，笔者仅考虑较大的颗粒 （d > 10 毫米），并模拟仅 1000年颗粒的短管。定量的分歧，观察结果。为了使计算更现实，本作者考虑了更小的粒子 （d = 3 毫米)、 不再管 (L = 8 m) 和模拟超过 40000 粒子。弹簧和阻尼器的非线性模型已从事目前的工作，结合有限差分法及单纯形方法 （压力-链接方程的 Semi-Implicit 方法）。

結果 (中文) 3:

散装物料气力输送已经成为许多行业的一个重要技术：从药品到佩特罗化工及发电。
这是由于产品质量要求的不断提高，与环境立法。当前许多工业集中在一个特定的模式浓相输送被称为“塞流”。这种低速气力输送已经引述造成较小颗粒的磨损，减少部件的磨损，并降低能源成本。由于这些原因，塞流系统被广泛应用在许多现代工业应用。【1】离散元法（DEM），有时被称为离散单元法，广泛用于模拟颗粒流。该方法在颗粒系统中的应用的开创性工作是由库德尔和施特拉克进行（1979）[ 2 ]。同时他们开发的程序模拟组件的盘球。早期的工作集中在“弹簧和阻尼器来表示粒子相互作用。Y. Tsuji [ 3 ] [ 4 ]进一步发展和改进的库德尔和施特拉克的模型，在DEM在塞流系统仿真首先采用。Ergun方程施加给流体的力作用在颗粒在移动或固定床。在模拟清楚地观察到波浪状的流动边界的运动。并获得良好的协议固定的沉积层高度和塞流速度之间的关系。但由于计算时间的限制，本文只考虑大颗粒（D＞10 mm），以1000粒子模拟短管。观察到的结果定量的分歧。为了使计算更接近现实，本文作者认为较小的颗粒（D = 3 mm），长管（L = 8 m）和40000以上的粒子模拟。一个非线性弹簧和阻尼器的模型已被应用在目前的工作中结合有限差分法和简单的方法（压力-半隐式方法与方程
）。