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20 / April 2021 powderbulk.com COMPARING HORIZONTAL AND VERTICAL DRYERS IN DYNAMIC DRYING When considering whether to use a horizontal or vertical dryer for dynamic contact drying, there are a few aspects to consider. What material type are you using? Does your material have specific process parameters? Is your process a batch or continuous one? This article describes how horizontal and vertical contact dryers work and what material each dryer is best suited for. Jan Wankerl, BHS-Sonthofen vertical and horizontal configurations. Increased process efficiency, the gentle handling of sensitive materials, and the elimination of temperature and humidity fluctuations make dynamic contact drying the method of choice for a variety of applications ver- sus traditional stationary drying. In industrial production processes, achieving a consistently high-quality material is of the utmost importance. Material quality may suffer during drying, especially if the temperature and humidity fluctuate over the course of the process. When your goal is to consistently and precisely maintain defined operating parameters during the drying process, dynamic drying is preferable to stationary drying. Mixing while drying material During contact drying, whether taking place in a hor- izontal or vertical dryer, as shown in Figure 1, the material being dried is continuously mixed with mix- ing instruments (such as blades or a helix) throughout the entire drying process. Because new particles are V ertical or horizontal dryers — which dryer is right for what type of task? Each dryer has its own advantages and disadvantages, as shown in Table I. Vertical dryers work well for batch processes, whereas horizontal dryers can manage batch and con- tinuous processes. Also, both dryer types can handle a variety of materials. Ultimately, the decision of whether to use a horizontal or vertical dryer depends on your application's process and end product. Before you decide on a vertical or horizontal dryer, you need to determine if you're going to use a station- ary or dynamic contact drying process. In a stationary or static dryer, the material being dried remains still on a tray or conveyor belt while the drying takes place. Stationary dryers, such as industrial drying ovens, are good for drying highly fragile materials with shear forces. In a dynamic contact dryer, the material is continuously mixed with paddles or blades while being dried. Compared to traditional stationary dryers, which don't provide even heat distribution, dynamic contact dryers offer a number of advantages in both Horizontal Vertical Mode of operation Continuous and batch Batch Applications From powder to high-viscosity slurries and filter cakes From liquids to free-flowing bulk materials Advantages High energy input and therefore increased potential drying capacities Near complete material discharge and easy to clean Highly suitable for food and pharmaceutical requirements Limitations Difficult to completely empty and reduced cleanability Can't operate in continuous processes TABLE I A comparison of horizontal and vertical contact dryers.