RU2241182C1 - Heater for lump raw material - Google Patents

Abstract

FIELD: building and metallurgical industry, particularly equipment for thermal treating carbonate material.

SUBSTANCE: heater has body with lining, gas-distribution chamber and loading chute arranged coaxially one to another, annular collector, unloading means and insert arranged above unloading means for heated raw material displacement to periphery. Gas-distribution chamber is made as diffuser with divergence angle of 5^o - 40^o. Unloading means is made as round rotary table with lining having working surface inclined to table center at an angle of 3^o - 15^o.

EFFECT: increased efficiency of rotary furnaces, decreased fuel consumption and power inputs.

1 dwg, 1 ex

Description

The invention relates to devices for heat treatment of lumpy carbonate rocks (limestone, dolomite, magnesite, etc.) with hot gases and can be used in metallurgical, chemical, construction and other industries.

The closest in technical essence is the heater of the lime kiln (US patent No. 3766663, CL F 26 B 17/12, CL USA 34/168, 432/106). The heater includes a cylindrical lined casing expanding in the middle part, a feed stream, an annular gas distribution chamber located under the expanding part of the casing, through many holes connecting to the flues, an exhaust gas collector installed in the center of the casing, a holding zone in the lower tapering part of the casing, installed an insert above the discharge opening to displace the heated raw materials to the periphery.

The disadvantages of this heater:

- when high-temperature dusty gases pass through the holes in the refractory dividing wall, the latter will inevitably overgrow with lime dust; cleaning of nastily will require labor and time;

- overgrowing and clogging of the holes leads to an uneven distribution of hot gases over the cross section of the layer and, accordingly, to a decrease in the thermal efficiency of the heater;

- counterflow heat exchange is characterized by the initial contact of hot gases with heated material, which is the cause of the formation of cakes, which, dropping down, clog the discharge chute.

The technical task of creating a heater is:

- improving the reliability of the heater (increased productivity, reduced operating costs, including cleaning and repairs, eliminating the formation of accretions and cakes);

- reduction of unit costs of electricity and fuel.

To solve this problem, in a lump of raw material heater containing a lined body, a coaxial gas distribution chamber and a charging chute, an annular collector located between the heat and the casing, an unloading device and an insert installed above it to displace the heated raw materials to the periphery, the gas distribution chamber is made in the form of a diffuser with an expansion angle of 5 ... 40 °, and the unloading device is in the form of a rotating annular table with a lining, the working surface of which is inclined to the center under glom 3 ... 15 °. The lining of the casing, the wall of the chamber and the free slopes of the raw materials (under the chamber, as well as between the estrus and the casing) form a heating zone in which heat exchange between the gases and the raw material proceeds. Under the heating zone is a holding zone, in which the temperature is equalized in pieces and in the layer.

The proposed essential features ensure the achievement of the following technical results during operation of the heater:

- the implementation of the gas distribution chamber in the form of a diffuser allows to reduce the speed of the gas flow without loss of pressure;

- a decrease in the velocity of the gas stream at the entrance to the layer and passing through it will provide a decrease in pressure losses in a quadratic dependence;

- the entry of hot gases into the cold layer of raw materials eliminates the formation of cakes in it over the entire range of operating temperatures (up to 1200 ° C), which ensures the intensification of the process;

- the implementation of the unloading device in the form of a rotating annular table with a working surface inclined to the center makes it possible to reduce the cost of manufacturing and operating the heater: the joining and lapping of the hearth to the body is simplified, the pieces are not bonded and compacted when moving to the center, the consumption of heat-resistant steel is eliminated.

The execution of a gas distribution chamber with an expansion angle of more than 40 ° leads to excessively high pressure losses in the diffuser itself - up to 30% of all losses. With an opening angle of less than 5%, the diffuser loses its main function: to extinguish the gas flow rate without loss of pressure. Giving the working surface of the table a slope of more than 15 ° will complicate the adjustment of the rate of descent of raw materials, since small changes in the angular velocity of the table will lead to significant and uncontrolled changes in the consumption of raw materials. When the angle is less than 3 °, compaction and abrasion of the raw material occurs and at the same time the load on the drive increases.

The analysis of scientific, technical and patent literature shows that there are no coincidences of the distinguishing features of the inventive lump raw material heater with signs of known technical solutions. Based on this, it is concluded that the claimed technical solution meets the criterion of “inventive step”.

The following is an embodiment of the invention, not excluding other options within the claims, with reference to the drawing, which shows a diagram of a lump raw material heater (vertical section along the axis).

The lump raw material heater consists of a housing 1, a gas distribution chamber 2, a feed chute 3, feed pipes 4, a raw material hopper 5 formed by the housing lining, a chamber wall and free slopes of the raw material 6 of the heating zone 7, the holding zone 8, the annular collector 9, the unloading table 10, drive 11, insert 12, discharge opening 13, discharge chute 14, flues 15, grate 16. Position α denotes the angle of inclination of the surface of the table lining towards the center, and position β denotes the expansion angle of the diffuser tion chamber. Heater of lump raw materials works as follows.

Example. Raw materials, for example, limestone of a fraction of 20 ... 50 mm from the hopper 5 by gravity through pipelines 4 and through the feed chute 3 enters the housing 1 of the heater. On the way, the fine fraction is separated from the raw materials on the grate sieve 16, the ingress of which into the heater can lead to a significant increase in the aerodynamic resistance of the heated raw material layer. From estrus 3, the feed enters the annular heating zone 7, forming a free slope 6, and then into the holding zone 8. In the annular heating zone 7, heat is exchanged between the gas and feed streams. Hot gases (products of the combustion of fuel and CO ₂ released during the dissociation of CaCO ₃ ) at a temperature of 1000 ... 1200 ° C through the flues 15 and through the gas distribution chamber 2, made in the form of a diffuser, enter the feed layer located under the funnel under chamber 2. Angle β expansion of the diffuser of chamber 2 is 5 ... 40 degrees, due to which a decrease in the gas flow rate before entering the layer occurs with virtually no pressure loss. The initial contact of the gas and the raw material occurs in the direct flow, and in the upper part of the slope 6 under the chamber 2, the hot gases come in contact with the cold raw material, due to which high values of the heat transfer coefficient are achieved within 12 ... 18 kW / m ³ · deg. Then the gases in the layer of raw materials are rotated by almost 180 degrees and are sent to the manifold 9, while continuing to contact the falling raw materials in countercurrent. The collector is used to collect the cooled gases leaving the upper slopes, and transfer them through the gas treatment unit to the exhaust fan. As a result of contact, the exhaust gases almost completely give off physical heat to the raw materials, heating its surface to 850 ... 900 ° C and subjecting it to dissociation by 10 ... 20%. Due to the decrease in the gas flow rate before entering the layer, the pressure loss in the layer itself is significantly reduced. Heated raw materials are characterized by temperature heterogeneity both within individual pieces and in the layer as a whole. When raw materials fall into the holding zone 8, the temperature is equalized. The temperature of raw materials discharged from the heater is 700 ... 800 ° C.

Unloading of the heated raw materials from the heater is carried out through the discharge opening 13 connected to the unloading estrus 14. The central estrus 13 is provided on the rotary table 10. The latter is rotated by the drive 11. The rotation speed of the table is 0.3 ... 0.8 rpm. Due to the inclination of the working surface of the table lining to the center at an angle of 3 ... 15 ° C, the unloading of the heated raw material proceeds without a fire, and also without compaction and destruction of the material. The insert 12 pushes the heated raw materials from the central part of the heater to the periphery, which ensures uniform discharge over the cross section of the heater.

The application of the present invention allows to increase the productivity of rotary kilns by 15-20%, reduce fuel consumption by 13-18% and electricity by 5-8%.

Claims (1)

A lump of raw material heater, comprising a lined body, a coaxial gas distribution chamber and a charging chute, an annular collector located between the heat and the casing, an unloading device and an insert installed above it to displace the heated raw material to the periphery, characterized in that the gas distribution chamber is made in the form of a diffuser with an angle expansion 5 ... 40 °, and the unloading device - in the form of a rotating annular table with a lining, the working surface of which is inclined to the center at an angle of 3 ... 15 °.