SU665191A1 - Method and apparatus for thermal treatment of pulverulent material - Google Patents

Description

one

The invention relates to the field of heat treatment of dispersed or granulated materials in a heat carrier stream and can be used in the pulp and paper industry for heat treatment of process chips, for the regeneration of lime from lime sludge, etc.

The known method of heat treatment of dispersed material by influencing the flow of heat transfer fluid on the material during countercurrent movement of the heat transfer fluid and the material in the conical and cylindrical parts of the heat exchanger includes: its upper cylindrical and lower conical parts made in the form of a retort, feed hopper for feeding the material, pipelines for supply coolant and pipe for unloading the processed material 1.

The known method does not allow to provide high quality heat treatment of the material and to conduct the process quite effectively.

The aim of the invention is to increase the efficiency of the process.

The goal is achieved by the fact that the heat treatment of the material is carried out at the flow rate of the heat-transfer fluid in a narrow section of the apparatus body equal to. (0.8-

l, 2) -t / BHT. and at the height of the layer of material calculated by the formula:

H (&, Q) -D, .UJU ,,,.,

where H is the height of the layer of material, m;

DO is the diameter of a narrow section of the conical part of the housing, m;

i / o - flow rate of the coolant in a narrow section of the conical part of the housing of the apparatus, m / s; vpt - speed of material particles helix, m / s.

The method is carried out by an apparatus, the difference of which is that the diameters of the cylindrical part and a narrow section of the conical part of the body of the apparatus are related by the relation:

,

0

where d

diameter of the cylindrical part of the apparatus, m; DO-diameter of narrow section of the conical part of the apparatus case, m; and the height of the conical part of the apparatus is not less than the diameter of its narrow section.

Apparatus for carrying out the method

presented in the drawing. The device includes

retort 1, feed hopper 2 for feeding

material in the retort, pipelines 3 for

supplying the heat carrier and the nozzle 4 for discharging the processed material from the apparatus.

The method of heat treatment of dispersed material using the apparatus is carried out as follows.

The initial dispersed material is loaded into the bunker 2, from where it is continuously fed to the retort 1. In the retort 1 a suspended layer of material is formed, which is formed by the material flow from the bunker 2 and the coolant flow, which is fed into the retort 1 from the bottom through pipelines 3. In the lower part of the retort into its A narrow section forms a gas gap A, which is formed by the flow of heat-transfer agent, acts as a supporting device for the material in the retort and keeps it in suspension. The dispersed material from the hopper 2 enters the retort 1 and during the heat treatment process gradually moves from top to bottom under the influence of the continuous loading of fresh material from the bunker 2, receives the necessary heat treatment and then removes it through the nozzle 4.

The method of heat treatment of a material can be carried out only if the required characteristics of the suspended layer are achieved, which are achieved by an appropriate set of design parameters of the retort and operating parameters of the coolant supply.

Experimental studies of the invention have established that if the design parameters of the retort satisfy the following relationships:

),

where D is the diameter of the cylindrical part

body of the apparatus, m; DO is the diameter of a narrow section of the conical part of the body of the apparatus, m, and the operational parameters of the process are given the ratio:

t /, 3 (0.8-1,2)., „,.

I (6.0-7.0). BUT. ,",.,

where I - the height of the layer of material, m;

PP - flow rate of coolant in a narrow section of the conical part of the apparatus, m / s; Vit - speed of helix particles of material, m / s,

then in the retort the weighted layer mode is realized, which is characterized by the following features.

In the layer there is no longitudinal mixing of the material and a uniform distribution of the material in the transverse and longitudinal sections of the layer is observed.

When the material loading into the retort is stopped, the material unloading in the lower part of the retort is stopped, and the height of the material layer remains constant in the retort. If a material is loaded into a retort with a certain amount of material, the material is unloaded in a part of the retort with the same intensity, and the height of the material layer in

the retort is also kept constant. At the same time, the material in the retort moves from top to bottom, i.e., from the beginning of processing to its completion. The rate of movement of the material is determined by the volume of the retort and the intensity of the loading of the material and, thus, can be controlled with greater accuracy by the loading mode. When serving in the lower part of the retort

coolant with a certain temperature is filtered through a layer of material. The temperature of the coolant drops due to the heat transfer to the material, and the corresponding

heat treatment zones. The material, moving from top to bottom, consistently passes them and receives the necessary heat treatment stages. The residence time of the material in each

The heat treatment zone is determined by the intensity of the material loading into the retort, as well as the duration of the heat treatment zones, which in turn are determined by the flow rate and temperature of the heat transfer medium and the intensity of heat transfer from the heat transfer medium to the material.

The noted characteristics of the caged layer eliminate the longitudinal mixing of the material and achieve the formation of several heat treatment zones in one retort, continuously following one after the other, and also ensuring control over the residence time of the material particle in all heat treatment zones, which leads to high quality heat treatment of the material.

The above characteristic features of a suspended layer are preserved not only in the case of processing a dispersed material with a uniform particle size distribution, but also in the case of a heterogeneous particle size composition of a material or a material of different density, if the deviation of particle sizes from the average does not exceed ± 40%, from the average does not exceed ± 20%.

Pilot tests of the lime regeneration process were carried out

weighted layer with the following installation parameters.

The diameter of the narrow section of the body (Do) is 100 mm, the diameter of the cylindrical part (D) is 250 mm, the height of the conical part of the body

(h) 200 mm, the height of the cylindrical part of the body is 1000 mm, the flow velocity of the coolant in a narrow section of the body (Lo) is 1.0 m / s, the soaring speed of the particles of material (Uvit.) is 30 m / s. The particle diameter of the material is 5-10 mm. The temperature in the burning zone, the residence time of the material and the burning zone is from 20 to 22 minutes.

The scatter in the residence time of the material in the burning zone is practically absent, which ensures a high uniformity of burning of the material particles in a single reactor and high quality of burning (the content of active CaO in lime is 87.5%, a value close to the maximum).

Claims (2)

1. The method of heat treatment of a dispersed material by exposing the flow of heat transfer fluid to the material during countercurrent movement of the heat transfer fluid and material in the conical and cylindrical parts of the heat exchanger, characterized in that, in order to increase the process efficiency, heat treatment of the material is carried out at a flow velocity of the heat transfer fluid in a narrow section the case of the apparatus is equal to (0.8-1.2) vit. and at the height of the layer of material calculated by the formula: I am 6, Och-7,0. D., ",., where H is the height of the layer of material, m; DQ — diameter of the narrow section of the crown part of the enclosure, m; i / o - flow rate of the coolant in a narrow section of the conical part of the apparatus, m / s; yit - speed of material particles helix, m / s. 2. An apparatus for carrying out the method according to claim 1, comprising an upper cylindrical and lower conical part, made in the form of a retort, a feed hopper for feeding material, pipelines for feeding a heat transfer medium and a nozzle for unloading the treated material, characterized in that the diameters of the cylindrical part and the narrow The sections of the conical part of the apparatus are connected by the relation: , 0 where D is the diameter of the cylindrical part of the apparatus, m; D. Diameter of a narrow section of the conical part of the apparatus, m; and the height of the conical part of the apparatus is not less than the diameter of its narrow section. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 220808, F 27В 15/00, 1967.  ) i / i / ly SM / T