SU95113A1 - The method of firing crushed material - Google Patents

Description

Loose chalk is not suitable for briquette; Vrovanu and it can not be burnt mine furnaces.

It has been proposed to burn loose, crushed chalk in a suspended state.

Odnzko, crisp firing schemes of loose chalk determine the hankling nature of the movement of chalk and tenlonobel (flue gases). Therefore, the flue gases of the heat carrier almost do not participate in the heating of the chalk, which requires up to 30% of the total heat spent on the production of lime; consequently, it is possible for the proper use of the physical tenlo of the flue gases in the well-known techiological scheme of lime production, so the heat losses from the flue gases are very large.

In addition, dust-like lime obtained by this method has a high temperature (900–1000 °) upon entering the dust collector, and in order to avoid large losses of finished products, it is necessary to expend considerable funds for the construction of complex dust removal systems.

The well-known principle of creating a counter-flow of solid particles and gas-carrier with the so-called "laying layer of material" also does not achieve the goal when firing loose chalk, because the grinding and separating devices cannot provide a grain size distribution of chalk, which is close to monofraction: 1: a fine grain output is obtained; for which it is virtually impossible to organize a falling layer; in addition, it is difficult to use the physical heat of the finished lime, and the process with a low coefficient of heat utilization.

It was also proposed to divide the flash material before firing in suspension in a vertical furnace into a crust and a fine fraction.

No

The described method of firing the crushed material, in particular, loose chalk, refers to these latter, but differs from them in that the coarse fraction is introduced into the furnace from above, whereby the bulk material is lowered uniformly, and the small fraction is introduced into the furnace from below and slid upwards along the mine air blown from below.

To reduce the removal of small and medium fractions of chalk and increase the degree of roasting, they reduce the speed of upward movement of the mixture of small fractions with air.

The drawing shows the implementation of the proposed method.

Preparation and roasting of chalk and cooling of the finished lime is carried out in a vertical kiln. In the middle of the furnace, the height of it comes from the half-furnace 2 of the gas that goes up, the burnout due to additional air supplied from the Lower part of the furnace. Coarsely ground in a mine mill 3, the chalk enters a large cross section mine 4, from which only fine particles are carried away, and the bulk of the particles fall down and are fed to the upper part of the furnace with a screw feeder 5. These large particles of chalk form a falling layer; moving towards the rising flue gases, they warm up, dry, and in the middle height of the furnace / are thermally decomposed; after that, a large part of them, due to the loss in weight, changes its direction and begins to move upwards, while the bulk of large particles continue to fall down through the lower zone of the furnace /.

Into the furnace / from below it enters from the outflowing air with suspended chalk fractions in it and moves upwards, meeting the falling large particles of lime and cooling them. At the same time, thin chalk fractions suspended in air are heated and dried. A considerable amount of heat is expended on this, which makes it possible to use only half the physical heat of large lime fractions to cool them to a temperature of 100 °.

From the bottom of the kiln / ready: the lime is removed through a conventional lock valve.

The fine fractions heated in the lower zone consume in the firing zone a minimal amount of high potential heat. The carrier air, which serves as secondary air for the afterburning of the semi-gas coming from the firebox, is heated in the lower zone to a high temperature, which favors the afterburning.

The calcined fine fractions continue to be carried up the cure; towards the falling layer of KpynHFJX particles of chalk, they give up their physical heat to heat the latter and get into a dust collector (cyclone) 6.

Medium-sized lime particles, which change their direction and move upward, also form an opposite layer in relation to the falling one and give it their physical heat.

Thus, heat losses with waste gases from finished products are minimized due to the oncoming movement of streams (layers) of suspended and falling particles.

A separate semi-gas furnace 2 can be replaced by burners built into the middle part of the furnace /.

The proposed scheme of counter layers can be applied not only when burning loose chalk and lime, but also in other cases of thermal processing of any kind of materials in a suspended state.

The burning zone of the furnace 1 can be made in the form of a diffuser; In this case, reducing the velocity of the gases in the cap will prevent the removal of large and medium sized particles from the burning zone. Longer residence of particles in the burning zone will provide a greater degree of decomposition. As for the fine particles of chalk, although they will immediately pass through the burning zone, the heat input and decomposition reactions for them are so intensified in the high temperature region that the burning of these particles is not completely ensured.

To reduce the average of the unit, the upper zone can be made smaller in diameter, creating an intermediate part B between it and the transition zone B in the form of a cofuser.

Subject matter

Claims (2)

1. A method of firing crushed material, for example, loose chalk, in a suspended state in a vertical furnace with a preliminary separation of the material into two fractions, characterized in that the coarse fraction is introduced into the furnace from above for uniform lowering, and the small fraction is moved from below and moves it up through the mine with air blown from below. 2. An implementation of the method according to claim 1, characterized in that the upward movement speed of the mixture of fine fractions of chalk with air is reduced, in order to reduce outflows and increase the degree of roasting. The priority of p. 2-27 nyu 1951  3 - № 95113 j1 Llj u with