scholarly journals Optimization Issues of a Hammer Mill Working Process Using Statistical Modelling

2021 ◽  
Vol 13 (2) ◽  
pp. 973
Author(s):  
Gigel Paraschiv ◽  
Georgiana Moiceanu ◽  
Gheorghe Voicu ◽  
Mihai Chitoiu ◽  
Petru Cardei ◽  
...  

Our paper presents the hammer mill working process optimization problem destined for milling energetic biomass (MiscanthusGiganteus and Salix Viminalis). For the study, functional and constructive parameters of the hammer mill were taken into consideration in order to reduce the specific energy consumption. The energy consumption dependency on the mill rotor spinning frequency and on the sieve orifices in use, as well as on the material feeding flow, in correlation with the vegetal biomass milling degree was the focus of the analysis. For obtaining this the hammer mill was successively equipped with 4 different types of hammers that grind the energetic biomass, which had a certain humidity content and an initial degree of reduction ratio of the material. In order to start the optimization process of hammer mill working process, 12 parameters were defined. The objective functions which minimize hammer mill energy consumption and maximize the milled material percentage with a certain specific granulation were established. The results obtained can serve as the basis for choosing the optimal working, constructive, and functional parameters of hammer mills in this field, and for a better design of future hammer mills.

2019 ◽  
Vol 11 (9) ◽  
pp. 2477 ◽  
Author(s):  
Georgiana Moiceanu ◽  
Gigel Paraschiv ◽  
Gheorghe Voicu ◽  
Mirela Dinca ◽  
Olivia Negoita ◽  
...  

In order to obtain bioenergy (biogas, biofuel) or pellets, different types of lignocellulosic biomass are subjected to a mechanical pretreatment, first by size reduction, then by separating, and ultimately by fracturing or bio-refining. Biomass processing mainly refers to a grinding process that occurs until reaching certain limits. The size reduction process, such as grinding, is an operation that is executed with different levels of energy consumption, considering biomass mechanical characteristics and the necessary grinding level. This paper, illustrates a comparative analysis of experimental results obtained by grinding multiple types of vegetal biomass (Miscanthus, corn stalks, alfalfa, willow) used in the process of bio-refining and bio-fracturing. Experiments were realized using both a laboratory knife mill Grindomix GM200 (Retsch GmbH, Haan, Germany), and a 22 kW articulated hammer mill, using different grinding system speeds and different hammer mill sieves. Results have shown that biomass mechanical pre-processing grinding leads to supplementary costs in the overall process through bio-refining or bio-fracturing in order to obtain bio-products or bio-energy. So, specific energy consumption for grinding using a hammer mill can reach 50–65 kJ/kg for harvested Miscanthus biomass, and 35–50 kJ/kg for dried energetic willow, using a 10 mm orifice sieve, values which increase processing costs.


2019 ◽  
Vol 14 (1) ◽  
pp. 100-106
Author(s):  
Константин Миронов ◽  
Konstantin Mironov ◽  
Николай Оболенский ◽  
Nikolay Obolenskiy ◽  
Вера Гоева ◽  
...  

Based on the analysis of existing studies of the process of grinding grain, the goal and objectives of the research were set, a crusher of a grain of impact-reflective action was developed. The results of theoretical studies of the working process of the grain crusher, including the study of grains’ movement along the beam and the determination of the trajectory of movement of particles in the grinding chamber, are given As a result of the study of various methods of supplying the material, the lowest energy consumption was obtained when the comminuted material was fed through the upper loading window. In order to determine the joint influence of the factors under study on the criterion of optimization and the exclusion of insignificant, the semi-replica of the full factorial experiment was implemented. Variable factors were the rotor speed, the angle of attack, the material feed, the diameter of the holes, and the angle of coverage of the end sieve. The optimization criterion was specific energy consumption. At the next stage, grain refinement was investigated using a peripheral sieve instead of an end sieve, as well as a peripheral sieve and an end sieve at the same time. It was found that with an increase in the angle of attack hit the percentage of the yield of the finished product through a peripheral sieve increases. Also, to compare theoretical and practical studies, paint was applied to the surface, and then the nature of paint wear was examined. From a photograph taken after grinding the grain, one can see that in the area characterized by a positive value of b, the paint has worn off (which indicates a sliding movement of the weevil), and in the area with a negative value of b, we can see blows of the weevils. That is, the presented theoretical dependences quite accurately describe the nature of the movement of the weevil in the grinding chamber of the crusher. In order to determine the optimal values of the studied factors, a second-order experiment plan was implemented. The method of superimposing two-dimensional sections of the response surfaces yielded optimal values of the factors under study. At the same time, energy consumption amounted to 1 ... 1.3 (kW ∙ h) / (t - measurement unit), and the amount of dust and whole grains does not exceed the norms stipulated by GOST.


2016 ◽  
Vol 70 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Djuro Vukmirovic ◽  
Jovanka Levic ◽  
Aleksandar Fistes ◽  
Radmilo Colovic ◽  
Tea Brlek ◽  
...  

In recent years there is an emerging trend of coarse grinding of cereals in production of poultry feed due to positive influence of coarse particles on poultry digestive system. Influence of grinding method (hammer mill vs. roller mill) and grinding intensity of corn (coarseness of grinding) on mill specific energy consumption and pellet quality was investigated. By decreasing grinding intensity of corn (coarser grinding), specific energy consumption of both hammer mill and roller mill was significantly decreased (p < 0.05). When comparing similar grinding intensities on hammer mill and roller mill (similar geometric mean diameter or similar particle size distribution), specific energy consumption was higher for the hammer mill. Pellet quality decreased with coarser grinding on hammer mill but, however, this effect was not observed for the roller mill. Generally, pellet quality was better when roller mill was used. It can be concluded that significant energy savings could be achieved by coarser grinding of corn before pelleting and by using roller mill instead of hammer mill. From the aspect of pellet quality, if coarser grinding is applied it is better to use roller mill, concerning that more uniform particle size distribution of corn ground on roller mill probably results in more uniform particle size distribution in pellets and this provides better pellet quality.


2020 ◽  
Vol 22 (2) ◽  
pp. 405-414
Author(s):  
Vasyl Arsiri ◽  
Oleg Kravchenko

AbstractThe indicator of the quality of modern turbomachines is only the coefficient of efficiency, which characterizes the ratio of the useful work of compressors or fans to the energy expended on the drive. For the analysis of the quality of the motion, processes in flow parts, the values of resistances are used which are difficult to be considered as an indicator of the efficiency of dynamic processes. The report presents the results of visual diagnostics of the structure of flows during the movement in the elements of turbomachines, as well as options for improving the geometry of the flow parts - in the inlet pipes, impellers.For the analysis of the efficiency of the motion of liquids and gases in flowing parts, a calculated index is proposed - the coefficient of hydraulic efficiency of dynamic processes. The joint use of two indicators - the efficiency of transformation of different types of energy (efficiency of turbomachines) and the efficiency of dynamic processes in flowing parts allows us to develop and to analyze the results of reconstruction of turbomachines. Reconstruction of turbomachines with the purpose of improving the geometry of the flow parts provides an increase in productivity of turbines, compressors, fans and pumps, while reducing the specific energy consumption for the processes of compression and transport of liquids and gases. Optimization of turbomachines flow parts based of flow structure visual diagnostics allows to reduce noise and vibration, as well as to solve other problems.


2017 ◽  
pp. 113-117
Author(s):  
E. R. Magaril ◽  
R. Z. Magaril ◽  
L. V. Trushkova

There were obtained the values of the relative reactivity of different types of bonds in interaction with hydrogen atoms, methyl radicals, as well as values of the effective relative reactivity when using an inert diluent, enabling to improve knowledge about the pyrolysis of raw materials of a given composition. A method was developed for increasing the selectivity of the pyrolysis for the desired products of the process (lower olefins), reducing the yield of liquid products of condensation and specific energy consumption, based on the influence of hydrogen on the thermal reactions of alkanes and alkenes.


1991 ◽  
Vol 27 (4) ◽  
pp. 324-329
Author(s):  
A. K. Mattis ◽  
S. V. Shishaev ◽  
G. D. Zaitsev ◽  
A. V. Tolmachev

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