RU2413577C1 - Vibration ball mill - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: invention relates to deep-drying and grinding devices. Vibration ball mill comprises cylindrical drum divided by perforated webs into sections. Said drum runs in flexible supports and is driven by two-mass inertial vibrator. Mill is filled with grinding bodies that feature sizes decreasing from loading sleeve to outlet. Part of the last section is perforated. Drum is furnished with heat exchange jacket with spiral tape insert to make coil channel to drying agent to pass into aforesaid heat exchange jacket. Drum last section perforation is made in it last part on length making not more than à of section length per 1/3 of surface perimetre. Loading sleeve is made up of two coaxial cylinders made from flexible material. Inner cylinder is perforated over all its length while outer, solid, cylinder is connected to drying agent discharge union. Drum every section is filled with grinding bodies for, at least, 0.5 of its volume. Web between I and II sections is solid at bottom half and perforated at top part, perforated holes are smaller than particle size of initial stock and grinding bodies of I section. ^ EFFECT: higher efficiency of producing dry powders. ^ 2 dwg

Description

The invention relates to devices for deep drying of materials with concomitant grinding and vigorous stirring for instrumental implementation of a method for producing powders from plant materials in continuous mode by contact-convection supply of a drying agent. Vibratory ball mill can be used in chemical, pharmaceutical, agricultural and food industries. It can be used for continuous grinding of mineral salts, dried fruits, berries; drying powders; mixing powders of solid substances, including during concomitant grinding and drying; mixing powders of solids with the liquid phase.

Known vibratory rotary ball mill [see patent No. 2147931, IPC В02С 17/06, 17/14, 2000], consisting of a cylindrical drum divided into sections, which is mounted in bearings with the possibility of rotation on a movable vibrating plate located on spring supports on a fixed base, which is equipped with a planar vibrator. To implement the continuous grinding process, the mill is made with a loading unit that ensures optimal filling of the drum with grinding bodies and crushed material. However, this design does not allow drying and grinding processes combined in time, and the mixing process is carried out by rotating the drum from a separate drive, which complicates the design and maintenance.

By design, the closest to the invention is a vibratory ball mill [see patent No. 2229340, IPC В02С 17/14, 2004], containing a cylindrical drum, divided by perforated baffles into sections, part of the last of which is made perforated, filled with grinding bodies with decreasing section sizes from the loading sleeve to the outlet, mounted on elastic supports and driven into circular vibrations by a two-mass inertial vibrator, while the drum is equipped with a heat exchange jacket having a spiral ribbon insert forming a helical channel for the passage of the drying agent in the heat exchange jacket e, the perforation of the last section of the drum is made in its lower part to a length of not more than 1/2 of the section length by 1/3 of the surface perimeter, while the loading sleeve is made in the form of two coaxially arranged cylinders of flexible material, the inner cylinder being perforated along its entire length, and the external, continuous, is connected to the nozzle for the release of the drying agent, and each section of the drum is filled with grinding media by at least 0.5 of its volume.

However, this design does not allow intensively carrying out the drying process in all sections of the drum, since through the perforated partitions of the sections, the crushed liquid phase is distributed evenly in the lower part of all sections, forming a continuous stationary medium from which moisture evaporates from its surface with the completion of the evaporated moisture from the internal volume of paste due to diffusion.

The objective of the invention is to increase the efficiency of obtaining dry powders with a narrow range of dispersion, increasing the rate of moisture removal by eliminating a continuous liquid medium from subsequent sections, concentrating it only in the first section of the drum.

The problem is solved in that in a vibration mill containing a cylindrical drum, divided by perforated baffles into sections, part of the last of which is made perforated, filled with grinding bodies with decreasing section sizes from the loading sleeve to the outlet, mounted on elastic supports and driven into circular vibrations by a two-mass an inertial vibrator, the drum is equipped with a heat exchange jacket having a spiral ribbon insert forming a helical channel for the passage of the drying agent into the heat exchange Oh shirt, the perforation of the last section of the drum is made in its lower part to a length of not more than 1/2 the length of the section on 1/3 of the perimeter of the surface, while the boot sleeve is made in the form of two coaxially arranged cylinders of flexible material, the inner cylinder being perforated along the entire length and the external, solid, is attached to the nozzle for the release of the drying agent, and each section of the drum is filled with grinding media by at least 0.5 of its volume, and the partition between sections I and II is made continuous in the lower half and perforated into rhney half with openings smaller than the size of feedstock particles prepared by grinding bodies and I section.

The proposed technical solution is not described in the literature. The solution to this problem was achieved by concentrating a continuous liquid phase (puree) in the first section of the drum in order to prevent the latter from spreading over all subsequent sections and to reduce the surface of evaporation of moisture from the continuous surface of the liquid phase by as many times as the sections were divided into a drum. When the level of the liquid phase is exceeded by 0.5 of the volume of the first section, the excess flows to the subsequent sections, forming a porous medium mixed with grinding media and a fraction of the dried processed material. When vibrating, the porous medium easily passes into a suspended state, which accelerates the process of moisture removal from the surface of conglomerates “grinding body - liquid phase”, “dried particle - liquid phase”. The combination of these techniques is absent in the prototype, therefore, the invention meets the criterion of "novelty."

When conducting a comparative analysis of the proposed technical solution with analogues, it was found that the combination of its distinguishing features, taking into account the achieved result, is also not known, which confirms compliance with the criterion of "inventive step".

Industrial applicability is confirmed by examples and a description of the operation of the device.

The invention is illustrated by drawings of a General view of the device (figure 1) and a cross section of the first section of the drum (figure 2).

The vibrating mill consists of a housing, which is a horizontal drum 1 (Fig. 1), having a heat exchange jacket 2 with a spiral ribbon insert 12, which forms a helical channel for the passage of the drying agent.

The length of the drum is divided into sections by perforated partitions 4, moreover, the partition between sections I and II is continuous in the lower half and perforated in the upper half of the surface with sizes smaller than the prepared particles of the feedstock and grinding bodies of section I, and the partitions of subsequent sections are perforated on the lower half of the surface. The size of the holes on the partitions decreases from the entrance to the exit to the drum, and in each section is smaller than the size of the grinding media. Each section is filled with at least 0.5 of its volume by grinding media 15, the size of which decreases from section to section. The end wall 10 of the last section has a perforation of 1/3 of the radius from the central axis of the housing, and the size of the holes corresponds to the particle size of the marketable products. In addition, the housing of the last section in the lower part to a length of no more than Ѕ the length of the section by 1/3 of the perimeter of the surface of the housing of the last section has openings 9 for the exit of the coolant from the shirt into the housing. The drum is mounted on elastic supports 5 (figure 2) having the same stiffness in the vertical and horizontal directions to ensure circular vibrations of the housing, to create which a two-mass inertial vibrator 3 is attached to the housing.

In the first section, there is a loading device consisting of a feed hopper 6, a loading sleeve 7 and a nozzle for draining the drying agent 8. The loading sleeve is made in the form of two coaxially arranged cylinders of flexible material, the inner cylinder being perforated along the entire length, and the outer, continuous, attached to the nozzle 8 to exit the drying agent (CA). The drying agent is fed into the jacket 2 through the nozzle 14. The finished product is unloaded through the perforated end wall 10 of the housing, the pipe 11 and the shutter 13.

Vibratory ball mill operates as follows.

Washed and pre-prepared raw materials are loaded into the feed hopper 6 and through the loading sleeve 7 completely fills the first section of the drum 1. At the same time, the feedstock is located in the hopper and the loading sleeve to maintain the fill factor in the first section 1. The maximum grinding intensity is ensured by the abrasive effect of grinding media bodies to particles of the feedstock, which at the same time goes into the state of a continuous liquid phase (paste) filling the lower part of the I section. The excess liquid phase of the feedstock of more than 0.5 volume of the I section goes into subsequent sections, forming a porous medium with the loading of subsequent sections.

и параметрического критерия

для заданного габарита (диаметра корпуса Д), приводят загрузку в состояние интенсивного перемешивания, что способствует эффективному теплообмену между нагретой стенкой корпуса и загрузкой и удалению влаги с поверхности частиц загрузки и шаров. Сопутствующее измельчение частиц загрузки за счет ударно-истирающего действия мелющих тел постоянно обновляет поверхность испарения. Измельченное исходное сырье превращается в сплошную жидкую фазу (пасту) и заполняет нижнюю часть I секции. Избыток жидкой фазы исходного сырья более 0,5 объема I секции переходит через перфорированную перегородку между I и II секциями в последующие секции, образуя в них пористую среду в виде частиц измельченного сырья и шаровой загрузки с развитой поверхностью испарения влаги, при этом частицы сырья продолжают измельчаться и сушиться, получая тепло, контактируя с нагретой стенкой корпуса и нагретыми шарами, а также через конвективный теплообмен с сушильным агентом, проходящим через весь корпус от последней секции к первой. Сплошная жидка фаза (паста) сохраняется только в первой секции, а в остальных секциях имеет место дисперсная среда, находящаяся во взвешенном состоянии.Inertial vibrator 3 causes the housing to oscillate. Oscillation parameters (amplitude A and angular oscillation frequency ω) selected from the relation of the Froude criterion

and parametric criterion

for a given size (case diameter D), the load is brought into a state of intensive mixing, which contributes to efficient heat transfer between the heated wall of the body and the loading and removal of moisture from the surface of the loading particles and balls. The concomitant grinding of loading particles due to the shock-abrasive action of grinding media constantly updates the evaporation surface. The crushed feedstock turns into a continuous liquid phase (paste) and fills the lower part of the first section. The excess liquid phase of the feedstock of more than 0.5 volume of the I section passes through the perforated partition between the I and II sections to the subsequent sections, forming a porous medium in the form of particles of crushed raw materials and ball loading with a developed surface of moisture evaporation, while the particles of raw materials continue to grind and dried, receiving heat, in contact with the heated wall of the body and heated balls, as well as through convective heat transfer with a drying agent passing through the entire body from the last section to the first. The continuous liquid phase (paste) is preserved only in the first section, and in the remaining sections there is a dispersed medium in suspension.

A drying agent (hot air) is supplied to the heat exchange jacket through the fitting 14 and, passing through the screw channel, heats the drum casing evenly over the entire surface, and when it reaches the perforated zone 9 of the last section of the drum, it enters the latter into the convective heat exchange zone. The increase in the cross-sectional area of the movement of the drying agent during the transition from the shirt to the case significantly reduces its speed, contributing to a more complete heat transfer between it and the particles in suspension, which intensifies the drying process. The drying agent, passing through the perforated partitions of the sections, enters the first section, completely filled with the initial wet product, where it is preheated and completely cleaned of the entrained fine fraction of the finished powder, which adheres to the wet surface of the particles of the initial product when passing through the pores between the particles. Purified, cooled and saturated with moisture vapor drying agent is removed through the nozzle 8.

Ready dry powder fills the last section of the drum at 2/3 of the height along the radius, which eliminates the wear of grinding media, and excess powder is removed through the perforated end wall of the last section, discharge hatch 11 and shutter 13.

The study of the drying process in a vibratory mill of potatoes and chokeberry showed an increase in actual productivity compared to the analogue by 1.2-1.5 times due to the exclusion of a continuous liquid phase from the subsequent sections except for the first with combined contact-convective heat transfer between the drying agent and the load.

Claims (1)

A vibrating ball mill containing a cylindrical drum, divided by perforated baffles into sections, part of the last of which is made perforated, filled with grinding bodies with decreasing section sizes from the loading sleeve to the outlet, mounted on elastic supports and driven into circular vibrations by a two-mass inertial vibrator, while the drum is equipped with a heat exchange jacket having a spiral ribbon insert forming a helical channel for the passage of the drying agent in the heat exchange jacket e, the perforation of the last section of the drum is made in its lower part to a length of not more than 1/2 of the section length by 1/3 of the surface perimeter, while the loading sleeve is made in the form of two coaxially arranged cylinders of flexible material, the inner cylinder being perforated along its entire length, and the external, continuous, is attached to the nozzle for the release of the drying agent, and each section of the drum is filled with grinding media by at least 0.5 of its volume, characterized in that the partition between the I and II sections is continuous in the lower half and the perforation it is open in the upper half of the surface with openings smaller in size than the prepared particles of the feedstock and grinding bodies of the first section.

Images