RU2425312C2 - Shaft furnace for burning lump material - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: shaft furnace consists of lined shaft with zones of heating, burning and cooling, of ceramic core with channels communicating with fuel combusting devices and cavity of furnace, of loading and unloading devices, and also of fuel combusting devices - core and periphery - mounted on upper and lower tiers of burning zone. The furnace is equipped with devices for withdrawal of hot air from the zone of cooling and combustion products from a lower section of the burning zone and for their supply into the heating zone made in form of radial horizontal channels in furnace lining located in an upper section of the cooling zone and a middle section of the heating zone. The channels communicate with working surface of the furnace and interconnected with pipelines positioned outside working space of the furnace.

EFFECT: upgraded quality of burning due to counter-flow in burning zone and direct flow of combustion products and burned material; increased zone of burning due to reduced zone of cooling at maintaining thermal-technical characteristics of heating and cooling zones; maintaining general height of furnace.

3 cl, 3 dwg

Description

The invention relates to shaft furnaces for burning bulk material, for example limestone, and can be used in metallurgy, chemical, construction, as well as in soda and sugar industries.

Known vertical shaft limestone kiln company IPROMET SA, Bucharest, containing a lined shaft with zones of heating, firing and cooling, loading and unloading devices, as well as peripheral fuel burning devices installed on one tier, and two smoke exhaust fans. One of the fans draws flue gases from the upper part of the furnace, and the other takes hot air from the cooling zone and part of the flue gases from the lower part of the firing zone and delivers them through pipelines to the fuel-burning devices. The temperature of the gases taken by this fan in the technological mode is 550-600 ° C.

A disadvantage of the known furnace is the high cost of a fan operating at temperatures of 550-600 ° C, in connection with its manufacture from expensive heat-resistant steels and ceramics. The use of fans made of cheaper materials reduces the reliability of their work. Such fans at high temperatures quickly fail and during operation require a decrease in the speed of rotation of the impeller, which leads to a deterioration of gas dynamics in the furnace and a decrease in the temperature of the air supplied to the combustion.

In addition, the air taken from the cooling zone has a high dust content and, when supplied to the fuel-burning devices, incapacitates them, clogging the nozzle with dust, which reduces the reliability of the furnace as a whole.

Closest to the claimed device in technical essence and the technical result achieved is a shaft furnace for firing bulk materials, containing a lined shaft with heating, firing and cooling zones, a ceramic core installed in the firing zone and having channels communicating with fuel-burning devices and the furnace cavity, loading and unloading devices, as well as fuel and core burning devices and peripherals installed on the upper and lower tiers of the firing zone. The gas distribution sectors are closed ceramic structures with horizontal channels communicating through openings with the cavity of the central pillar. The cooling zone is equipped with a device for removing hot air and supplying it to the upper core channels in the firing zone (see patent RU 23217809 C2, 08/20/2007).

This device is taken as a prototype.

A disadvantage of the known furnace is its low reliability, due to the fact that the air taken from the cooling zone is dusty and its supply to the upper channels of the ceramic core leads to clogging with dust. The supply of this air to the burner devices of the firing zone also clogs them with dust, which generally leads to a decrease in the reliability of the furnace.

In addition, in the known furnace during the technological process it is impossible to change the size of the firing zone, which does not allow to obtain lime with an adjustable extinguishing time without changing the furnace output, since the extinguishing time, with other equal furnace parameters and limestone characteristics, depends on the calcination temperature and lime residence time in the firing zone.

The problem to which this invention is directed, is to increase the reliability of the furnace and optimize the distribution of heat fluxes in the shaft of the furnace.

The problem is solved in that in a shaft furnace for firing lump material containing a lined shaft with heating, firing and cooling zones, a ceramic core having channels communicating with fuel burning devices and the furnace cavity, loading and unloading devices, as well as fuel burning core devices and peripheral installed on the upper and lower tiers of the firing zone, the feature is that it is equipped with devices for the selection of hot air from the cooling zone and combustion products from the lower the second part of the burning zone and feeding them into a preheating zone constructed as radial horizontal channels in the lining of the furnace, located at the top of the cooling zone and the middle part of the preheating zone communicating with the furnace working space and interconnected pipes located outside the oven space.

In addition, the peculiarity is that control devices are installed on the pipelines.

In addition, hatches for cleaning these sections were made on horizontal sections of pipelines.

The inventive combination of essential features allows to obtain the following technical result.

Supply of the furnace with devices for taking hot air from the cooling zone and combustion products from the lower part of the firing zone and supplying them to the heating zone, made in the form of horizontal radial channels in the lining of the furnace located in the upper part of the cooling zone and the middle part of the heating zone in communication with the worker the space of the furnace and interconnected pipelines located outside the working space of the furnace, increases the reliability of the furnace, since with this direction of gas flows the possibility abivaniya dust core channels and burner fuel combustion devices.

The selection of hot air from the cooling zone and combustion products from the lower part of the firing zone and their supply to the heating zone is carried out without the use of blowing means by their natural movement due to the pressure difference in these zones of the furnace, which reduces the cost of the design of the furnace as a whole.

The selection of hot air from the cooling zone and combustion products from the lower part of the firing zone and supplying them to the heating zone improves the quality of firing due to the organization of countercurrent and direct flow of combustion products and fired material in the firing zone, and also increases the firing zone by reducing the cooling zone while maintaining thermotechnical characteristics of the heating and cooling zones and while maintaining the overall height of the furnace.

Lengthening the firing zone and the possibility of changing its size, provided with the help of control devices installed on the pipelines, allows you to get lime with an adjustable extinguishing time.

The lengthening of the firing zone and the organization in the firing zone of countercurrent and direct flow of combustion products and fired material increases the productivity of the furnace by 10 - 15% while achieving a higher degree of limestone decarbonization.

The invention is illustrated by drawings, where figure 1 shows a shaft furnace, a longitudinal section, figure 2 - section a - a in figure 1, figure 3 - section bB in figure 1, figure 4 - view In figure 1.

The shaft furnace for calcining bulk materials contains a lined shaft 2 enclosed in a casing 1 with heating zones 3, calcination 4 and cooling 5. A ceramic core 6 is installed in the shaft 2, having channels 7 communicating with fuel-burning devices and the furnace cavity. On the upper tier of the firing zone 4, fuel-burning core devices 8 and peripheral 9 are installed, on the lower tier - devices 9. A loading device 10 is installed in the upper part of the shaft 2, and an unloading device 11 is installed in its lower part. For air extraction from the upper part of the cooling zone 5 and parts of the combustion products from the lower part of the firing zone 4 in the lining of the shaft 2 are made of radial horizontal channels 12 in communication with the working space of the furnace. To supply a mixture of air and combustion products in the heating zone 3 in the lining of the shaft 2, radial horizontal channels 13 are made, also communicating with the working space of the furnace. Channels 12, 13 are interconnected by pipelines 14 located outside the working space of the furnace.

The selection of exhaust gases from the mine 2 is carried out through the central 15 and peripheral 16 devices by means of a smoke exhaust (not shown).

Regulating devices — throttles 17 — are installed on pipelines 14, and hatches 18 are made on horizontal sections of pipelines 14 for cleaning these sections of dust coming from air taken from cooling zone 5.

Shaft furnace for firing bulk materials works as follows.

Bulk material to be fired, such as limestone, with the help of a loading device 10 enters the heating zone 3 of the shaft 2, where it is heated by the combustion products of the fuel.

When the material moves down through the firing zone 4, it is fired in countercurrent combustion products. Most of the combustion products (about 85-95%) coming from fuel burning devices 8, 9, rising upstream in countercurrent with falling limestone, pass through the calcination zone 4 and the heating zone 3, give their heat to the calcined material and are removed from the furnace through the central 15 and peripheral 16 channels through a smoke exhaust (not shown).

A smaller part of the combustion products (5-15%), moving in the lower part of the firing zone in a direct flow with the fired material, is mixed with air supplied for cooling lime, and through channels 12, pipelines 14 and channels 13 enter the heating zone 3, from where removed through the central 15 and peripheral 16 channels through a smoke exhaust. The mixture of air and flue gases, taken from the cooling zone 5, has a temperature of 700-800 ° C. The supply of this mixture to the heating zone 3, where the process proceeds at similar temperatures, improves the convective heat transfer between flue gases and limestone and, as a result, feeds material with a higher temperature into the calcination zone.

Unloading of the finished product from the cooling zone 5 is performed by the unloading device 11.

Using the present invention allows to increase the firing zone by reducing the cooling zone while maintaining the thermal characteristics of the heating and cooling zones and maintaining the overall height of the furnace. This increases the productivity of the furnace and the quality of firing due to the organization in the firing zone of countercurrent and direct flow of combustion products and the fired material.

Claims (3)

1. A shaft furnace for burning lump material, comprising a lined shaft with heating, firing and cooling zones, a ceramic core having channels communicating with fuel burning devices and a furnace cavity, loading and unloading devices, and core and peripheral fuel burning devices installed on the top and lower tiers of the firing zone, characterized in that it is equipped with devices for taking hot air from the cooling zone and combustion products from the lower part of the firing zone and supplying them to the heating zone a, made in the form of radial horizontal channels in the lining of the furnace, located in the upper part of the cooling zone and the middle part of the heating zone, communicating with the working space of the furnace and interconnected by pipelines located outside the working space of the furnace. 2. A shaft furnace according to claim 1, characterized in that control devices are installed on the pipelines. 3. The shaft furnace according to claim 1, characterized in that hatches for cleaning these sections are made on horizontal sections of pipelines.

Images