SU1257391A1 - Rotary kiln - Google Patents

Abstract

The invention relates to the field of heat treatment of bulk materials in rotary kilns and can be used in alumina industry. The purpose of the invention is to simplify the reliability of the furnace. A rotary kiln comprising a body with a refractory lining and a heat shield placed on the outer surface of the body. The screen is made in the form of a solid shell, installed coaxially with the body of the discharge end of the furnace to form an airtight cavity for filling it with a working substance. 1 il. you ate oo

Description

The invention relates to the heat treatment of particulate materials in rotary kilns and can be used in alumina production.

The aim of the invention is to increase the reliability of the rotary kiln for alumina calcination.

The drawing shows a schematic of a furnace.

The rotary kiln for calcining alumina consists of a cylindrical body 1, a discharge end, inside which the refractory lining 2 is placed. The furnace butt is closed by a cover head 3, in which the burner 4 is placed. The bottom of the head 3 rests on the discharge shaft 5. On the outer surface of the body 1 the discharge end of the furnace is placed a heat shield 6, made in the form of a solid shell, installed outside the coaxial body and forming with it a splody annular sealed cavity 7. On the outside the surfaces of the screen 6 are made of fins 8, which increase the heat-transfer surface. The screen 6 is also equipped with a safety device (bursting plate 9 and pressure gauge 10). The annular gap between the screen 6 and the head of the cover is closed by a seal 11.

A rotary alumina calcination kiln works as follows:

Before starting work, the sealed cavity 7 is filled with a working substance and performs the function of a heat pipe.

. The heated material subjected to heat treatment flows out of the furnace in a continuous flow from the furnace into the discharge shaft 5. The source of energy for the heat treatment of the material is oil or gas burned with a burner 4. The body 1 is protected from overheating from the inside by means of a refractory lining 2. However, the end of the body 1, entering inside the head of the shelter 3, is subjected to intense heating and from the outside by radiation from the hot material entering the shaft, as well as from the hot lining of the head of the cover 3. Therefore, disposed about the outer surface of the heat shield 6, which prevents the housing 1 from overheating and deformation Thu provides resistance in the lining

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This zone also increases the reliability of the operation of the discharge end of the furnace.

The very intense heat radiation flux comes from below from the discharge charge 5 and falls on the lower part of the heat pipe of screen 6. Here boiling up of the working substance (liquid) takes place, which consumes a significant amount of thermal energy, due to which the outer wall of the heat screen is effectively cooled. Liquid vapors spread throughout the entire volume of the heat pipe and condense on colder surfaces outside the cover of the cover 3. The condensed liquid droplets flow back to the boiling point, since it occupies the lowest position. More active condensation of vapors of the working body is facilitated by fins 8, which increase the heat-release surface and accelerate the flow of heat into the environment. The implementation of the heat shield 6 from a solid annular shell with the formation of a heat pipe with the furnace body provides a more efficient removal of heat penetrating to the body and through the lining 2.

The presence of screen 6 safety device S 1 allows you to maintain the integrity of the screen in case

emergency condition of the furnace, for example, unforeseen destruction of the lining 2 in the area of the housing 1 closed by a heat shield. And the installation of the pressure gauge 10 makes it possible to judge the state of the working fluid inside the heat pipe.

Making the heat shield from a continuous ring-shaped heat pipe greatly simplifies its design while simultaneously increasing the efficiency of heat removal from the overheating zone of the body, which reduces the number of emergency stops of the calcination furnace due to destruction of the discharge lining end up to 2-3 times a year, reduces overhead costs the restoration of the lining and heating of the furnace after an emergency repair, which consumes fuel and electricity. In addition, the reduction in the number of heat changes as a result of more reliable operation of the discharge end of the furnace contributes to an increase in the service life

the entire lining of the furnace, reducing the cost of its refurbishment.

Claims (1)

Invention Formula A rotary kiln predominantly for calcining alumina, containing a cylindrical housing with a discharge end, placed on its inner surface refractory The lining and heat shield installed on the outer surface of the case are distinguished by the fact that, in order to increase reliability, the heat shield is made in the form of a continuous shell mounted coaxially with the body of the discharge end of the furnace to form an airtight cavity for filling with the working substance. 10 9  6 (I ||| . X k to xx x X Bf Editor K. Voloshchuk Compiled by N. Novikov Tehred I. Veres Proofreader E. Roshko Order 4904/35 Circulation 561 Subscription VYIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4