RU216399U1 - Electric rotary kiln with sectional heating - Google Patents

Abstract

The utility model relates to continuous furnaces for heat treatment of finely dispersed material or suspensions at a controlled heating temperature in continuous operation and constant mixing of the material. The technical result of the utility model is the provision of zones with controlled temperature support inside the furnace drum for the implementation of standard technological processes of chemical, construction, machine and metallurgical production. The specified technical result is achieved by the fact that the electric rotary kiln with sectional heating, containing a heating device made in the form of a multi-turn cylindrical inductor; smooth-walled drum mounted coaxially inside the heating device, based on rollers mounted on the frame; drum rotation drive; thermal insulation fixed on the drum coaxially to the inductor throughout the entire hot zone; loading and unloading mechanisms that have thresholds and a gas exhaust system, characterized in that the heating device consists of several modules (sections) of the induction system, each of the modules includes its own inductor, matching device and inverter (generator). In this case, regardless of the parameters of each module of the induction system, a magnetic coupling will occur between adjacent inductors, which must be taken into account and its consequences minimized when designing the system. However, there are no strict restrictions on the use of methods for loading and unloading the working material in the furnace. Also disclosed are various modifications of the furnace with a description of their functional application.

Description

The utility model relates to continuous furnaces for heat treatment of finely dispersed material or suspensions at a controlled heating temperature in continuous operation and constant mixing of the material.

Rotary kilns are known for roasting cement clinker (RU 91141 U1, publ. 01/27/2010, RU 2648734 C1, publ. 03/28/2018), expanding expanded clay (RU 2210042 C1, publ. 08/10/2003), production of porous aggregates (RU 2055289 C1, publ. 27.02.1996), cement and chemical industries, metallurgical, refractory and machine-building plants [1]. The common and main disadvantage of all the above furnaces is the use of internal heat-insulating lining of furnaces, which wears out during operation, and therefore requires a shutdown of the production line and scheduled repairs, which can last for months, since the average dimensions of the drum of large rotary kilns are about 3 m in radius and 35-50 m long. There is a solution to the indicated problem in the form of using external thermal insulation of the furnace, which is used as a prototype for a utility model.

The closest to the proposed utility model in technical essence is an INDUCTION FURNACE WITH A RETORT (RU 198165 U1, publ. 06/22/2020), containing a heating device made in the form of a multi-turn cylindrical inductor, a retort installed coaxially inside the heating device, with on it with thermal insulation, which provides isolation of the retort from the inductor throughout the entire hot zone; the loading mechanism is made in the form of an auger, the unloading mechanism is provided with an additional threshold and an unloading chamber located behind it, having a hatch for dumping part of the waste material and the possibility of connection with a gas outlet pipe.

The disadvantage of the known device is the lack of controlled temperature zones necessary to ensure the production processes of standard rotary kilns with smooth or at least stepwise heating (thermal preparation, degassing, sintering, calcination, swelling, roasting, etc.).

The task solved by the utility model is to provide zones with controlled temperature support inside the furnace drum for the implementation of standard technological processes of chemical, construction, machine and metallurgical production.

This problem is achieved in that the electric rotary kiln with sectional heating, containing a heating device made in the form of a multi-turn cylindrical inductor; smooth-walled drum mounted coaxially inside the heating device, based on rollers mounted on the frame; drum rotation drive; thermal insulation fixed on the drum coaxially to the inductor throughout the entire hot zone; loading and unloading mechanisms that have thresholds and a gas exhaust system, characterized in that the heating device consists of several modules (sections) of the induction system, each of the modules includes its own inductor, matching device and inverter (generator).

In this case, regardless of the parameters of each module of the induction system, a magnetic connection will occur between adjacent inductors, which must be taken into account and its consequences minimized when designing the system [2].

In FIG. 1 schematically shows the proposed electric rotary kiln with sectional heating.

In FIG. 2 is an example of a diagram of the formation of temperature regimes in an electric rotary kiln with sectional heating.

Electric rotary kiln with sectional heating includes a drum 1 installed coaxially with several modules (sections) of the induction system 2, which in conjunction with the drum 1 constitute a heating device. The drum 1 is isolated from the modules of the induction system 2 by thermal insulation 3.

The drum 1 has supporting discs 4 for installation on rollers 5 fixed on the frame 6. Sections of the induction system consist of an inductor 7, a matching device 8 and an inverter (generator) 9, also fixed on the frame 6 to maintain the alignment of the device.

The mechanisms for hermetic loading and unloading of the working material can be made in various versions, necessary to ensure the filling of the drum 1 with the working material, depending on the technological processes in production. Frame 6, if necessary, can be additionally equipped with hinges for turning the device at a certain angle to the horizon.

Electric rotary kiln with sectional heating operates as follows. The working material is fed into the loading mechanism. In a smooth-walled drum 1, made of heat-resistant steel, heat is generated by means of an eddy current induced from an alternating electromagnetic field of a cylindrical inductor 7 of a modular induction system 2. Rotating, the drum 1 evenly distributes the working material along its entire length. Due to the external thermal insulation 3 and the required number of modules of the induction system 2, different temperature zones are created inside the drum 1. The length of the drum 1 is determined by the zones necessary for the production process, and can reach values at which it will be necessary to use additional support disks 4 in order to avoid mechanical overvoltage and destruction of the device heating.

As the temperature zones pass inside the drum 1, the working material is evenly heated in accordance with the stages of technical processing. For example, using the proposed solution, it is possible to implement a furnace for the production of expanded clay with successive zones of thermal preparation, swelling and annealing. For the occurrence of heating reactions, accompanied by the release of volatile products, certain technological parameters are required, such as the thickness of the layer of the material being calcined, the time spent in the calcination zone, and the performance of the device. Constant maintenance of the thickness of the layer of the material being annealed ensures the threshold of the end flange. The required performance is determined by the optimal geometry of the furnace drum 1, which depends on the maximum temperature of the process and is based on the use of relationships between productivity, inner radius and drum length [3].

After the threshold on the end flange, the material enters the discharge chamber. The discharge of the material can be carried out in the cold chamber. The discharged part of the material corresponds to the continuously incoming flow of material from the loading chamber.

If necessary, due to the hermetic loading and unloading of the working material, an isolated atmosphere is created inside the drum 1, the flow rate of which can be adjusted using an external gas control system.

The use of several modules of the induction system, including its own inductor 7, a matching device 8 and an inverter (generator) 9, makes it possible to achieve the temperature control of the working material necessary for the technological process, as, for example, is shown in the graph of figure 2. Temperature zones alternate with zones of power reduction from - due to the need to reduce the influence of the magnetic coupling of adjacent inductors and the inclusion of additional supporting disks 4 in the design. As can be seen from the graph, the zones of reduced power have almost no effect on the temperature of the working fluid due to external thermal insulation 3.

If necessary, modification is possible to tilt the frame 6 and the axis of rotation of the retort at an arbitrary angle with respect to the horizon.

Since the utility model has been described in sufficient detail, it will be apparent to those skilled in the art that it can be modified in various ways without departing from the spirit and scope of the utility model. All such modifications are intended to be included within the scope of the appended claims.

Bibliographic list of information sources

1. Lisienko V.G. Rotary kilns: heat engineering, management and ecology: Reference book: In 2 books. Book 1 / V.G. Lisienko, Ya.M. Shchelokov, M.G. Ladygichev. - M.: Teplotechnik, 2004. - 688 p.

2. Abdulkhakov I.Yu. Magnetically coupled systems of induction heating with individual posts of food Cand. … cand. tech. Sciences: 05.09.10 / I.Yu. Abdulkhakov. - St. Petersburg, 2019. - 163 p.

3. Patent of the Russian Federation RU 198165 "INDUCTION FURNACE WITH RETORT" dated 06/22/2020.

Claims (2)

1. An electric rotary kiln with sectional heating, containing a heating device, a smooth-walled drum installed coaxially inside the heating device, based on rollers mounted on a frame, a drum rotation drive, thermal insulation fixed coaxially on the drum throughout the entire hot zone, loading and unloading mechanisms , which have thresholds, and a gas exhaust system, characterized in that the heating device is made of sections of the induction system, each of the sections includes its own inductor, matching device and generator, mounted on the frame coaxially with the drum. 2. Electric rotary kiln according to claim 1, characterized in that swivel hinges are installed on the frame.

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