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Absorber Optimization
Published in Kenneth Schifftner, Air Pollution Control Equipment Selection Guide, 2021
In a packed tower, the packed bed design and operation provides the basis upon which the desired mass transfer of the contaminant gas into the liquid can be achieved. The packed section (or “absorption” or “contact” section) is essentially of mechanical design (the surface of the absorbing or cooling liquid being mechanically increased, or “extended” as that liquid passes over the media) but that often exhibits a “chemical” function. As the gases are absorbed, for example, there may be an exotherm that could reduce the absorption of subsequent gases through the reduction in gas solubility. The absorbed gases may react with chemicals in the liquid thus producing reaction products that may reduce the rate of absorption. Those reaction products may also produce solids and/or scale that can mechanically affect the flow of the liquid over the packed bed media. As a result, various types of packing may be harnessed by the designer to maximize the mass transfer while minimizing solids build up and scaling. The options range from dumped type to structural.
Multiphase Flows with Droplets and Particles
Published in Greg F. Naterer, Advanced Heat Transfer, 2018
A packed bed is a hollow tube, pipe, or other vessel that is filled with a packing material such as particles. The packing can be randomly filled or it can have specifically structured packing and materials. Packed beds may also have catalyst particles or adsorbents which facilitate chemical reactions. The purpose of a packed bed is to enhance the contact area between two phases, typically gases and particles. Packed beds arise in various industrial systems such as chemical reactors, distillation columns, and scrubbers which remove gases from industrial processes prior to release to the atmosphere.
Experimental and numerical investigations on the local wall heat transfer coefficient in a narrow packed bed with spheres
Published in International Journal of Ambient Energy, 2022
Surfarazhussain S. Halkarni, Arunkumar Sridharan, S.V. Prabhu
In the chemical engineering field, the packed bed devices are used in a wide range of transport processes to enhance diffusion, reaction, catalysis, absorption and desorption, etc. In the present times, the utility of these packed bed systems is used in renewable energy power plants such as solar power, thermal energy storage, etc. In the present work, experimental studies are conducted to understand the heat transfer characteristics in packed beds with lower bed to particle diameter ratios (D/dp ∼ 1.25) in which only a single ball can be packed in each horizontal plane. The fluid flow happens in the void space between the walls and the packed balls. Colburn (1931), Leva (1947) and Leva and Grummer (1948) are the first set of researchers who have studied the wall heat transfer coefficient in packed columns initially. They have performed experiments with a bed to particle diameter ratio (D/dp = 2.5–3.5) and maintained constant wall temperature.
Effect of magnetic field on a loosely packed, tightly packed and an over-tightly packed metal powder bed
Published in Particulate Science and Technology, 2021
Kavin Sundarnath J. Ayyanathan, Sarada Kuravi
The pressure drop in a packed bed cannot be predicted analytically and accurately in all circumstances as the powdered particles often come with different sizes and shapes. Koekemoer et al. found that the material type of the particle and the particle size distribution affects the pressure drop of the packed bed, and introduced new constants in the Ergun equation (Koekemoer and Luckos 2015). Tian et al. studied the influence of wall effects on the pressure drops in packed beds. They concluded that equations of Ergun type with constant coefficients cannot predict the friction factor accurately and proposed improved correlations for wall corrected friction factors for spherical and sintered ore particles (Tian et al. 2016). This reflects that the transport properties of the packed bed largely depend on the packing, size and, shape of the particles, and the properties of the fluid as well. They also included that the values were in reasonable agreement with the Ergun equation with modified shape factors.
Simulation investigation on marine exhaust gas SO2 absorption by seawater scrubbing
Published in Journal of the Air & Waste Management Association, 2022
Wenjun Li, Yongxin Zhang, Zhongyang Zhao, Chang Liu, Yifan Wang, Mingqiang Shen, Haobo Dai, Yang Yang, Chenghang Zheng, Xiang Gao
A scrubber is the key equipment of EGCS, mainly including a spray scrubber, packed bed and bubbling reactor. The packed bed can achieve large contact area and residence time when liquid flows over the packing inside the column. Some scholars have studied the performance of packed bed when it is applied in EGCS (Flagiello et al. 2018, 2019; Iliuta 2019). However, the packed bed has drawbacks such as the disintegration of packing material and clogging of the packing due to deposition (Iliuta 2019; Javed, Mahmud, and Purba 2006) in some specific situations. For the bubbling reactor, high interfacial areas can be achieved depending on the size of bubbles but a high cost resulting from large pressure drops can be produced which for marine application is a strong limit. In spray scrubbers, the absorbent liquid is dispersed into small droplets to counter-currently contact and mix with the exhaust gas entering the spray scrubber. The application of spray scrubber in marine desulfurization has also been reported in some studies and some structure design and optimizations have been proposed (Caiazzo et al. 2013; Flagiello et al. 2019; Han et al. 2018). With the advantages of simple structure and high operational stability, spray scrubbe has applied widely in wet fuel gas desulfurization technology for power plants (Zhong et al. 2008). It is predictable that spray scrubber has also a good application prospect in marine EGCS. Whereas different from land desulfurization spray tower, the application of spray scrubber in EGCS faces more problems due to the different application scenarios and complex sea conditions during sailing. On the one hand, limited space of ships results in a requirement for more compact spray scrubber compared to land desulfurization spray tower. On the other hand, it is noticeable that the ship could swing during sailing when wave intensity in the sea is excessive, which leads to spray scrubber incline and influences the performance of thespray scrubber. Therefore, it is significant to develop spray scrubber with high adaptability for marine vessels.