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Energy and Environment
Published in T.M. Aggarwal, Environmental Control in Thermal Power Plants, 2021
In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers. The coal is next pulverized into a very fine powder. The pulverizers may be ball mills, rotating drum grinders, or other types of grinders.
Human-in-the-Loop Control
Published in William S. Levine, Control System Applications, 2018
Harry G. Kwatny, Claudio Maffezzoni, JohnJ. Paserba, Juan J. Sanchez-Gasca, Einar V. Larsen
Finally, in coal fired units fuel is supplied by pulverizers, not influenced by the rest of the plant. The pulverizers have sluggish dynamics due to the dead time of the grinding process and to the uncertain behavior of such machines caused by coal quality variation and machine wear. For those plants, where fuel flow cannot be considered a directly manipulated variable, the slow response of coal pulverizers must be cascaded with the evaporator dynamics of Figure 11.7 often creating severe problems for system stability and control.
Introduction to Powder Handling Processes
Published in linoya Koichi, Masuda Hiroaki, Watanabe Kinnosuke, Powder and Bulk Solids Handling Processes, 2017
linoya Koichi, Masuda Hiroaki, Watanabe Kinnosuke
Figure 1.3 shows the cement production process. The raw materials, such as limestone, silica, clay, and slag, are roughly pulverized and blended. The intermediate materials are pulverized again. The size reduction of particles in this stage is carried out carefully because the degree of calcination depends strongly on particle size. The feed materials for the second mill are thus well dried, so that the mill works smoothly. The mill feed rates should also be controlled; otherwise, it is difficult to meet the size specifications. The output powder of the mill is stored in a silo or a feed hopper.
Separation and characterization studies of end-of-life mobile printed circuit boards
Published in Particulate Science and Technology, 2021
G. Ellamparuthy, S. I. Angadi, D. S. Rao, M. K. Ghosh, S. Basu
Comminution of EoL mobile PCBs is one of the essential processing stages that eases the liberation of metals and nonmetallic materials. Association of electronic components on bare EoL mobile PCBs is complicated as these components are varying in size and exhibit different material properties such as brittleness, ductile, malleable, and hardness. Besides, copper layers of very thin foil in micron size are laminated by non-conducting polymer substrate, with many adjacent layers arranged one over the other. For recycling EoL mobile PCBs, metallic and nonmetallic component liberation is of prime importance that could be achieved following comminution. The liberation of materials bounded by screws and rivets is easy than the elements bounded by coating, binding, welding, and encapsulating. Alloyed, coated, etched materials cannot be unlocked by comminution (Zhang and Forssberg 1997). The EoL PCBs components are hard and malleable as a result impact mills are extensively used for liberation of metals and nonmetals, which occur at a coarser size due to lower interfacial bonding between the components. Literature (Koyanaka et al. 2000; Yoo et al. 2009; Oliveira et al. 2009; Vidyadhar and Das 2013; Eswaraiah and Soni 2015) reports various types of crushers/mills were employed to reduce the particle size of EoL PCBs. Laboratory scale investigations involve size reduction by hand cutting, mechanical cutting, guillotine, etc. in the primary stage. Further size reduction was achieved following impact mills, hammer mills, and pulverizers.
Study of particle size distribution of pulverized coals in utility boilers
Published in Particulate Science and Technology, 2018
The particle size analysis is utilized to estimate the performance of the grinding circuits (pulverizers) and to build the degree of liberation of the values at different particle sizes after size reduction. A varied number of methods aiming at determining PSD like mechanical sieving, cycloning, microscopy, and so forth have been described in the literature (Gómez 1990; Dierickx et al. 2000). However, it is essential that the PSD analysis methods must be precise and trustworthy as necessary alterations in plant operation may be based on the results of the laboratory tests. Therefore, controlling PSD is necessary for increase in productivity and quality of products (Zhang et al. 2012).