SU773410A1 - Tunnel furnace - Google Patents

Description

(54) TUNNEL FURNACE

one

The invention relates to equipment for the production of calcining large-sized carbon products in the metallurgical and electric-coal industries.

Tunnel kilns are the most sophisticated units for burning products. Compared with other types of kilns, they are more economical in terms of fuel consumption and labor demand, they most fully automate the burning process and achieve relatively accurate adjustment, improved working conditions for personnel, as loading and unloading products produced outside the furnace.

The use of tunnel kilns for burning carbon products is associated with a number of difficulties caused by the specific properties of carbon materials. First, when firing in an oxidizing environment, there are large losses on the oxidation of products. Secondly, when heating and burning products from them, resinous shoulder straps are released, which, if not removed or create an oxygen-free atmosphere in the furnace, light up in the high-temperature zone, causing overheating and oxidation of the products. There are a number of ways to eliminate these shortcomings.

A well-known tunnel kiln, in the side walls of the working channel of which a series of inlets are made for dispersed supply of inert flue gases to it and w, spruce refuse to discharge resinous discharge gas throughout the entire zone of their maximum release 1.

The system is difficult to manufacture and operate, but it prevents the main part of the resinous shoulder straps from entering the high-temperature zone of the working Channel, where their combustion is undesirable. During the circulation of gases, partial burning of resinous shoulder straps occurs with the use of heat in the process.

The closest to the technical essence and the achieved result to the proposed is a tunnel oven, made as follows. The working channel has heating, firing and cooling zones. At the beginning of the burning zone, two smoke exhausters are installed at some distance from each other. In the course of the products, the first exhaust fan sucks purge gases from the working channel along with resinous shoulder straps and supplies them to the catalyst for burning out resinous. After that, the gas is partially directed to the muffle channels located along the heating zone, and partly to the purge of the working channel from the inlet end. The second smoke exhauster sucks the higher-temperature gases with a lower content of resinous shoulder straps. These gases are also directed through two ducts to catalysts for burning off volatile, after which one stream of gases is cooled at the heat exchanger and used to flush the working channel from the output end, and the other stream is additionally heated in a flue gas burner and fed to the furnace working channel directly to firing zone 2.

However, the gases from the first exhauster are supplied to the muffle channels and to the furnace purge with the same temperature, which negatively affects the quality of the burned products, since to eliminate the cracking of the products and to obtain a uniform structure, heating is necessary, at least to 450 ° C with a smooth and uniform rise in temperature. In addition, with such input of purge gases, the gases discharged from the muffle channels must have a rather high temperature, which is uneconomical. The gases from the second exhauster are brought to the firing temperature mainly due to fuel burners. After leaving the furnace, gases with such a high temperature partially flow to the heat exchanger, which is not economically viable. In addition, both exhausters, especially the second one, work on gases having a BLiroKyic temperature. This increases the cost and complexity of the design of smoke exhausters (according to our data, the domestic industry does not produce such smoke exhausters).

The aim of the invention is to simplify the design, reduce the cost of building and operating the furnace, improving its technological properties, increasing its reliability and performance.

The goal is achieved by the fact that in a tunnel kiln for burning carbon products containing a working channel with successive heating, burning and cooling zones, muffle channels separated by partitions from the working channel, a combustion chamber with burners installed in it, located above the working channel and separated from it overlapping, gas blowers are installed at the exit end of the muffle channels at the beginning of the furnace and are connected by gas ducts to the working channel of the furnace on both sides, with the muffle channels They are made for the entire length of the heating and firing zones and are connected at the entrance to the combustion chamber.

The essence of the invention is that the working channel of the furnace is blown on both sides with spent

with thick gases, which donated most of their heat to the products in the muffle heating system. The muffle channels are laid along the heating and firing zones on both sides of the working channel. Purge

gases, along with resinous shoulder straps, are discharged from the working channel before the burning zone in the zone of maximum volatiles through the openings in the ceiling to the external combustion chamber. In the combustion chamber on fuel burners, resinous inclusions are burned and the gas temperature is brought to the burning temperature (1200-1300 ° C). The heated gases from the combustion chamber enter the muffle channels to the smoke exhausters installed at the inlet end of the furnace. Such countercurrent movement of hot gases to cold products and relatively cold blowing gases ensures smooth and uniform heating of products throughout the heating and roasting zones. FIG. 1 shows the oven, general view.

in terms of; in fig. 2 - the same, transverse section; in fig. 3 is a longitudinal section through the working channel; in fig. 4 is a longitudinal section through a muffle channel.

The furnace has four working channels 1 and five muffle channels 2. The walls 3 between the working and muffle channels are made of plates of structural graphite and fixed to the frame structures of heat-resistant concrete 4. Above the burning zone

J) there are five combustion chambers 5. The chambers have openings 6 for supplying enriched volatile gases from the furnace, burners 7, channels 8 for supplying hot air and openings 9 for exhausting flue gases into the muffle channels 2. Muffle

 The channels have baffles 10. For removal of gases from the muffle channels, there is a bore 11, into which gases fall through the openings 12. For collecting the gases from the bore, there are two smoke exhausters 13, one of which is back-up. The intake is made from the collecting chamber of the hog 14. Discharge chambers 15 are located behind the smoke exhausters, having outlets 16-18 with gates 19. The outlet 16 is connected to the distribution channel 20 having four openings for gas supply

S into the working zone of the furnace 21. The outlet 17 is connected to the chimney 22. The outlet 18 is connected to the duct 23, in which there are pipes of the heat exchanging device 24. Both the duct 23 (working and reserve) are connected to the duct 24, at the end of which there are openings 25 for the entry of gas into the working zone of the furnace. For the supply to the muffle channels of the air cooling zone, there are two fans 26 (working and standby) with a collection duct, taps and slide valves 27-29. Pipes 30 are provided for discharging heated air. The lock chambers are equipped with gates 31.

The furnace works as follows.

Trolleys with items in the backfill or without them are fed into the furnace through sluice chambers and using pushers (not indicated) move along the furnace in the direction of arrow A. Exhaust flue gases are fed into the furnace at both ends and move along arrows B. Gases moving with products, heated from contact with the walls of the 3 muffle ducts 2 and the products are heated and pre-fired. Gases, moving countercurrently with the products, first cool them, accumulate heat, and then, get into the burning zone between the heated muffle walls and the calcined products, heat up to the burning temperature and produce the products. The temperature of these gases is easily controlled by supplying cooling air to the muffle channels of the cooling zone in the direction of arrow B. The position of the burning zone is also regulated. When contacted with products, the gases in the furnace are enriched with volatile epaulets. When it enters the combustion chamber 5, the gases are heated by the heat obtained from burning the volatiles on the burners and by the fuel supplied to the burners. Hot air from the muffle channels of the cooling zone is used for combustion. The air supply is regulated so that when gases enter the muffle channels, the combustion of graphite plates is not observed. This is provided by means of sight pipes and instrumentation (not shown). The flue gases, moving along the muffle channel along the arrow T, release most of their heat through the wall, after which the exhaust fan is directed partly to the furnace at both its ends, and partly to be discharged into the chimney. Since volatiles are burned, gas scrubbing is not required. The gases supplied to the furnace for cooling the products pass through the heat exchanger 24. The degree of cooling of the gases on the heat exchanger is regulated in such a way as to ensure the cooling of the product to 400 ° C at the exit of the furnace.

The furnace is made of heat resistant concrete. The topochia chamber is lined on the inside with a refractory brick. The facing plates of the muffle channels can be made, for example, of structural graphite, and during installation they are mounted on

a solution of carbonaceous materials on a coke pitch composition used to obtain calcined products. The use of plates of structural graphite in addition to high heat resistance and thermal conductivity

walls provide a high degree of sealing them, since during the operation of the furnace all the cracks, gaps and pores are sealed with pyrolytic carbon, as with the aspirated gases containing resinous shoulder straps from the working channel into the muffle

Intensive deposition of pyrolytic carbon on iieli machines and its overgrowing begins. Carbonate slabs can also be used as slab material.

The use of this tunnel kiln for burning carbon products reduces capital investment by reducing the installation of refractory materials, reducing operating costs and improving product quality.

Claims (2)

Invention Formula Tunnel kiln for burning carbon products, containing a working channel with successively located heating, roasting and cooling zones, muffle channels separated from the working channel, a combustion chamber with burners installed in it, located above the working channel and separated from it by an overlap, gas blowing devices and devices for supplying cooling air, characterized by heme, in order to increase reliability, productivity and reduce the cost of building and operating a furnace, gas blower devices at the outlet of the muffle ducts at the beginning of the furnace, they are connected to the working channel of the furnace on both sides, while the muffle channels are made for the entire length of the zones heating and firing and inlet are connected to the combustion chamber. Sources of information taken into account in the examination 1. UK patent number 902674, cl. 51/2, published. 1959. 2. Patent of the USSR No. 417960, cl. F 27 B 9/00, 1967.