SU1516722A1 - Heat-and-mass exchange rotary apparatus - Google Patents

Abstract

The invention allows to intensify heat and mass transfer and reduce the amount of dust carried away from the rotary kiln of alumina (cement) production. This is achieved by installing in the rotary kiln vnutripechnyh heat and mass transfer devices of free-running chains fixed around the perimeter of the kiln, and a group of heat exchangers-activators 3, which are installed concentrically furnace in the boot end and fed into the processed material, and in the discharge end of the kiln fuel is burned the combustion products of which are passed through the furnace and heat exchangers. The heat exchangers-activators 3 rotate with a frequency higher than the rotational speed of the furnace, and in the areas of their rotation they create a volume zone of active contact of the processed material and furnace gases. The heat exchangers 3 are made in the form of rotating rings, equipped with actuators 7, mounted outside the furnace body. The axis of rotation of the rings at an angle of 90 ° intersect the axis of rotation of the furnace. In addition, the geometric centers of the rings are spaced apart by a distance greater than the internal diameter of the furnace. 2 Il.

Description

FI.2

The invention of Otositg to TechC - to achieve intensive heat and mass transfer in rotary kilns of the glucose industry and the building materials industry in the production of cement, and can also be used in other heat exchange rotating aggregates.

The aim of the invention is the intensification of heat and mass transfer and the reduction of yield from the furnace.

The pa of Fig. 1 shows a longitudinal section of the rotary kiln; figure 2 - section aa in figure 1.

The heat and mass transfer device of the rotary kiln 1 contains a free-running heat exchanger device installed at the charging end (not shown). Values are fastened in a circular order around the circumference of the furnace body 1. The weight of the hinge is

Hz. „1ts

  12 when -r I, and I

0.8,

tf.u, l- u.e

where F (is the surface of the chains;

RF c - surface area of the furnace, N

where they are hung; I (is the chain length;

Вц - diameter of the furnace in the chain

zone.

The chain curtain starts at a distance of 1.5 D and 3 from the cut-off of the furnace 1. The length of the chain curtain is 1.0 D cj. The pitch of the chains along the axis of the furnace 1 is 200 mm, and along the circumference of the C of O. mm. At a distance ID j (D g - the inner diameter of the furnace 1, D. D c 3) concentric with the furnace 1 and the fr om end of it, a group of heat exchangers-activators 2-A is installed, having the form of rings with hot-wire chain curtains fixed inside them around the perimeter 5. The density of hanging the chains inside the rings is 6-8. The length of each chain is 1.2-1.3 of the inner diameter of the ring (D j g), while the ratio

--- - 0.25 - 0.35 (where R is the arrow D to

sagging gryl ndy). The shafts of the 6 rings are equipped with electric drives 7, which are attached to the furnace body 1 Out; the shafts of the electric drives 7 are in counter-rotation and are rigidly connected to the rings of 6 rings, which are in place of them through the furnace body 1

0

5 0 5

0

five

in the bearings and bearings. The axes of rotation of the rings diametrically at an angle of 90 ° intersect the axis of rotation of the furnace 1, and their geometric centers 0 (; Oz coincide with the axis of rotation of the furnace 1 and are separated from each other at a distance greater than the internal diameter (Dg) of furnace 1, i.e. .

 DB and 0.0 DB.

If this condition is met, an emergency stop of one of the rotating heat exchangers 2-4 does not disturb the operation of adjacent rings.

The number of rings installed by the Q boot end of the furnace 1 is determined by thermal calculation. Learning high intensity of heat and mass transfer, all elements of rotating heat exchangers 2-4, which come into contact with furnace gases, are made of heat-resistant steel.

The conductor line 1e of the device and the trolley for supplying electrical power to the drives of the heat exchangers 2-4 are not shown.

The device works as follows, simultaneously.

An intrahepatic heat-exchanging device of free-hanging chains and a group of ten-exchangers-activators 2-4, having the shape of rings with developed (inside the rings) solid chain curtains 5, are installed in the loading end of the rotary furnace 1 and fed to it (loading end) the material to be treated is in the form of nepheline-limestone pulp with a relative humidity of 30%. The rings are rotated with a frequency co exceeding the rotation frequency of the furnace 1 (().

In Fig. 1, the arrows indicate the direction of rotation of the heat exchangers 2-4 of the furnace 1, as well as the movement of the material and the furnace gases.

The mixture moves through the furnace 1 by the expense of its slope (3%) and rotation (W / min) to the discharge end, in which the fuel oil is burned. The products of combustion are drawn with the help of two smoke exhausters through the furnace 1 and heat and mass transfer devices. The material being processed and the furnace gases flow countercurrently. Pa areas where the rings are installed, due to the frequency of their rotation () create a volume zone of active contact of the treated mixture and furnace gases.

515

Free-flowing chains play the role of a wet filter of the fine fraction carried out from the furnace 1, dust and fine particles of the material being processed, weighed into the gas phase by the heat exchanger-activator 2-4 closest to the cold cut. The heat exchange in the wet filter section is of a regenerative nature, in which the wet chains with adhered charge rise into the gas flow, are heated with waste gases, then sink into the wet charge layer, giving off their heat. The process of heat recovery occurs at a frequency equal to the frequency of rotation of the furnace () „.

The most intense heat and mass transfer occurs in the installation zone of heat exchangers-activators 2-4, which rotate at a frequency that exceeds the rotation frequency of the furnace 1. To evenly distribute the load and balance the resulting moments, each of the heat exchangers 2-4 is driven by two electric drives 7, which mounted on the outside of the furnace body 1 and operate in the opposite direction of rotation. The frequency of rotation of the heat exchangers (to) is determined experimentally by calculation, based on the conditions for creating a turbulent mixing mode and obtaining a given thermal power of the preparation zone of the furnace 1,

By creating a volumetric active contact zone of the material being processed and a turbulent aerohydrodynamic mixing mode (over the entire cross section of the furnace 1) of the gaseous, liquid and solid phases of the contacting media, the coefficient of convective heat exchange increases in proportion to the frequency of rotation of the heat exchangers-activators 2-4 ( U) | c)

6722

and volume concentration (G,) of particles

charge, weighed surface activators. At the same time, the coefficient of turbulent dynamic viscosity increases (the zones and with it its dust removal capacity, which can be expressed by the dust retention coefficient in the zone (Ku),

ten

the ability of the volume zone of active contact depends on the values of GV and (l).

In addition, due to the fact that the V preparation zone of the charge (especially in its wet part) intensifies the processes of mixing the layer, its transportation in the axial direction of the furnace 1 and the regeneration of heat between the layer of the charge and furnace gases.

Thus, the use of the proposed device intensifies heat and mass transfer and reduces dust removal from the rotary kiln, thereby increasing the productivity of the kiln,

the specific fuel consumption and weight of heat exchangers made of hot metal is reduced.

Claims (1)

Invention Formula A heat and mass transfer device of a rotary kiln containing rotating rotary heat and mass transfer elements installed inside the kiln, the rotation axes of which diametrically intersect the kiln rotation axis, characterized in that, in order to intensify heat exchange and reduce dust removal, heat and mass exchange elements are made in the form of a kiln mounted concentrically along the kiln axis groups of rings with fixed chain curtains fixed inside them around the perimeter; their geometric centers are located at a distance from each other and greater than the internal diameter of the furnace. f1amepuaf ( Furnace loading end Once narrow the end of the nevu. figure 1