UA55891A - method for granulation from liquid phase - Google Patents

Abstract

Method for granulation from liquid phase provides for introduction of heated gaseous fluidizing agent into apparatus filled with granules with formation of quazi-liquefied layer. At the volume of last one fluid is atomized. Rotational motion of granules with central upflow and peripheral downflow is formed. Liquid is atomized up to size of drops in granules upflow at the most 0.5 micron. Relative humidity of fluidizing agent in zone of fluid atomizing is kept equal to 100%.

Description

The invention belongs to heat and mass exchange equipment, in particular to methods of granulation in a fluidized bed and can be used in the chemical, food industry and mineral fertilizer production industry.

A known method of granulation from the liquid phase, in which a heated gaseous liquefying agent is introduced into the apparatus filled with granules to form a pseudo-liquefied layer, over the free surface of which a liquid is sprayed |Sazhyn V.S. Osovye! drying techniques. - M.: Khimiya, 1984. - P. 149, fig. 5.7, fig. During liquid spraying, its drops move from top to bottom towards the upward flow of the liquefying heat transfer agent. As a result of the sharp braking of these drops, they coalesce with each other with the formation of drops with a size of tenths of a millimeter or more.

When such drops fall on the surface of solid particles of the fluidized bed, uneven excessive moistening of these particles occurs, which leads to their spontaneous and unregulated agglomeration and subsequent significant violation of the particle size composition of the resulting product. In addition, this method involves a significant loss of liquid as a result of drops of liquid falling on the walls of the device.

The method of granulation from the liquid phase is the closest to the proposed invention, in which a heated gaseous liquefying agent is introduced into the apparatus filled with granules to form a fluidized bed and a liquid is sprayed into the volume of the latter (patent of Ukraine Me40356, IPC" B 01

In 2/04, publ. 16.07.2001, Bull. Mob).

In contrast to the considered analogue, this method, due to the spraying of liquid in the volume of the solid phase layer, excludes the sticking of the liquid phase on the walls of the apparatus, and therefore non-productive losses of the product due to its crystallization on the walls of the apparatus. However, the possible formation of large drops of liquid leads to the same consequences as in the indicated analogue. In addition, the impact of drops of a significant size on the granules of the solid phase and the subsequent evaporation from their surface of the liquid solvent lead to uneven "embedding" of the components of the liquid solution in the growing granule, and, accordingly, to the production of a product with an uneven distribution of components along the radius and on the surface of the granules . In addition, the strength of the obtained granules in this case turns out to be unsatisfactory.

The invention is based on the task of improving the method of granulation from the liquid phase, in which the new conditions of atomization of the latter ensure the production of strong granules of the solid phase with a uniform distribution of components along the radius and on the surface of the granules.

The problem is solved by the fact that in the method of granulation from a liquid solution, in which a heated gaseous fluidizing agent is introduced into the apparatus filled with granules to form a fluidized bed and a liquid is sprayed in the volume of the latter, according to the proposed invention, the new thing is that the apparatus forms a circulating the movement of granules with a central upward and peripheral downward flow, the liquid is sprayed to the size of drops no more

0.5 μm in the upward flow of granules, while in the area of liquid spraying they provide the relative humidity of the liquefying agent 10095

During the movement of granules through the indicated area, an ultrathin (at the molecular level) film of liquid is formed on their surface due to adhesion and sorption forces. After the granules leave the area of liquid spraying and the subsequent movement of the granules in the downward flow, the granules come into contact with the heated gaseous liquefying agent, which causes intensive removal of the solvent and the formation of microcrystals and microparticles of mineral and organic substances on their surface. After the next entry of granules into the area of liquid spraying due to liquid wetting, these microcrystals are firmly connected to each other and form a frame structure, inside which microparticles of organic substances are placed. As a result, a high-quality granular product with a uniform distribution of components, significant strength and low tendency to clumping and clumping during transportation and storage is obtained.

The product obtained according to the proposed method, compared to the product obtained according to the method - the closest analogue, has the ultimate stress during compression 2 times more, is not subject to caking and by 5095 has a more uniform distribution of components in the volume of granules.

The proposed invention provides a high-quality granulated product with a given dispersed composition and uniform content of components.

Claims (1)

The method of granulation from the liquid phase, in which a heated gaseous liquefaction agent is introduced into the apparatus filled with granules to form a fluidized bed, and a liquid is sprayed into the volume of the latter, which is distinguished by the fact that in the apparatus the granules form a circulation movement with a central upward and peripheral downward flow, the liquid spray to a droplet size of no more than 0.5 μm in the upward flow of granules, while in the area of liquid spraying ensure a relative humidity of the liquefying agent of 100,905.