SK1452004A3 - Method of production of concentrated and directional heat exchange in a rotating furnace and device for thereof - Google Patents

Abstract

Efficient combustion of gaseous fuel and thermochemical formation the annealing / sintering process and others materials in rotary kiln conditions. Flame is formed by the method of combustion of a homogeneous mixture at stoichiometric the balance of gas and air and is directed obliquely at the surface of the annealed material in the form of a volumetric stream with adjustable radial and meridial sector angle in the kinetic combustion process with significant proportion of radiant heat. Devices to create them medium and directed heat exchange consists of gas a burner burner with a length that exceeds the coolant zone, equipped with the necessary elements of different shape and location.

Description

Method for producing concentrated and directed heat exchange in rotary kilns and apparatus for producing it

Technical field

The invention relates to a method for efficient combustion of gaseous fuel and the formation of a thermochemical process of annealing or sintering refractory and other materials under rotary kiln conditions.

BACKGROUND OF THE INVENTION

PP 1137-2003 dated 10 September 2003 and ÚV no.

3698th

It is important to recall this knowledge to clarify this patent. Heat transfer takes place in three ways: radiation, convection and conduction, which have a specific heat transfer mechanism and are governed by different laws.

Of particular importance in annealing / sintering / material in rotary kilns are two types of heat transfer: convection and radiation.

The specific heat transfer by convection is defined by the granulometric characteristic of the powder materials according to the dust entrainment and radiation - using a low-temperature diffusion combustion process. According to literature data, the total proportion of heat transmitted by radiation in the presence of soot particles, in the case of a long burner, i. in the case of diffuse combustion is max. 18 to 20% of the total amount of heat received by the entire furnace surface and the material 6 to 7%. In addition, the known design of the burner devices, heating the refractory insulating layer of the furnace to practically the same temperature along its periphery, does not create conditions for efficient heat exchange between it and the fried roasted (sintered) material as the furnace is rotated. Therefore, some of the thermal energy received by the flame-resistant heat-insulating layer is lost as a result of thermal conductivity and radiation to the surrounding environment.

In this way, a comprehensive analysis of the operation of gas-fired rotary furnaces shows that the existing combustion engine design and heating space aerodynamics do not provide optimal high efficiency coefficient of useful efficiency and eliminate the possibility of controlling the direction and concentration of heat flow to the annealed zone material, which is accompanied by considerable heat and material losses.

Conversion of rotary kiln operation to a high-temperature gas-fired mode to a kinetic zone of 2100 to 2150 ° C with a radiant fraction of 55 to 65% requires the creation and development of complete aerodynamics of the heater and special burner devices ensuring heat flux concentration in the location sector of the annealed / sintered material, heating to the combustion apparatus of the supplied gas and air to account for the thermal energy of the cooling zone.

The aim was therefore to create an efficient annealing / sintering / heat and mass exchange process at the expense of the principal change in flame aerodynamics and its orientation in the combustion chamber of the high temperature gas combustion process with structural confirmation of its execution ensuring technological parameters of the thermodynamic annealing / sintering process / stoichiometric combustion. a homogeneous mixture reaching the maximum temperature of the burner with the transformation of thermal energy into heat, creating a short and strong flame and improving its heating of gas (up to its combustion) and air due to cooling of the burner as well as high partial pressure of water vapor generated during combustion increase the degree of “blackness” of the flame and also the rational utilization of the radiant capacities of the heat-resistant insulating layer of rotary kilns by using the heat obtained from the flame as a result of heat exchange of the flue gas stream. due to its "distribution" and "adhesion" in the zone of contact with the material to be heated to heat it.

Radiant heat transfer in high-temperature furnaces is critical, since in this way 80-90% of all the heat produced by the heated material is transferred (A.I.Evdokimov, V.V.Kosterin, Natural Gas in Color Metallurgy, "Metallurgia", M., 1972, p. 62 ... 65,141 /. In this case, for the intensification of the heating, the flame temperature can be higher than the temperature of the refractory lining by 370 ° C or more. When the air is heated from 273 to 770 ° K, the flame spread rate increases 2 and more times, and fuel consumption decreases by 34% / Glinkov M. A., Stepanov M.E., VUZOV Reports Black Metallurgy, 1961, No. 9, p. 143; Zaberežnyj, I.I., Use of heated air in color metallurgy furnaces. "Metalurgizdat", 1958, Bašanov L.I.a.kol. Non-ferrous metals. 1967, no. 1, p.37 /.

To address the complex challenge of increasing the overall efficiency of the thermodynamic annealing / sintering / powdering process, combustion was located in the annealing / sintering / homogeneous mixture zone, corresponding to stoichiometric equilibrium with complete premixing of gas and air with the combustion process of the concentrated and directed heat exchanges in the form of a pyramidal flame consisting of individual strands coming from the mixing chamber of the burner with an angle of opening of the sector of 35 to 40 °, the axis of which was at right angles to the surface radially

->

A segmented layer of annealed material whose length in the direction of its movement ensures the course of the thermodynamic process. The rate of discharge of the mixture from the mixing chamber nozzles exceeds the rate of combustion, avoiding the retraction or skipping of flames into the burner interior (Stoliner, E. B., Pauleva, E.F.). Report for the personnel of gas-fired boiler rooms. “Nedra”, 1990, p. 199 /. This method known from PP 1137-2003 resp. ÚV 3698 can be applied in certain combustion conditions.

For the cooling of the burner assembly, an annular burner structure is provided, including an outer annular gas collector, extending at the front to the inner gas collector disposed axially in the air collector and an effective cooling system for its outer surface or systems located parallel to the perimeter of the gas ducts gas to the mixing chamber, cooling the walls along the entire length by controlling the gas velocity mode at minimum friction resistance coefficient with boundary layer turbulization in the zone of increased heating of the external surface of the burners from radiation / Slichting, G., Boundary Layer Theory. 1969 s. 569 /.

To reduce the hydraulic resistance of the air collector and to reduce the electrical energy consumption of the blower fan drive, the property of the gas ejected into the air collector space is utilized to transform kinetic energy into potential and potential energy into kinetic / Budrin, D.V., Glinkov, M.A., et al. Metallurgical furnaces. Part 1. State Technical Publishing House for Black and Color Metallurgy, M. 1963, p.252 /, using ejection forces for the gas-air mixing process at optimal gas flow rates in the mixing chamber / Butakov, S.E., Aerodynamics of Industrial Ventilation Systems. VNIIOT, Moscow 1949, p.86 ... 105 /.

In order to reduce the heat losses in the mixing chamber and the cost of the electric drive of the smoke exhaust fan due to the uncontrolled air intake in the furnace head, a collector-type measuring device is mounted to control the volumes of fired products corresponding to their volume, excluding their passage.

The choice of geometry, design parameters of pyramidal stream components and its orientation when burning a homogeneous stoichiometric mixture is determined by the conditions for achieving the target and depends on the properties of the annealed material, the technological parameters of rotary kilns, air and gas pressure enabling the cooling zone to warm the environment. and transforming the mixture at the expense of energy / pressure / gas capabilities with minimal hydraulic resistance to the air supply system.

SUMMARY OF THE INVENTION

It is an object of the present invention to create a controlled efficient heat exchange and heat energy concentration of strong, short and high temperature flame and to conserve energy sources, the flame is produced by a homogeneous combustion process at stoichiometric gas and air balance and directed in a non-pyramidal shape. a flame consisting of individual strands coming from the burner mixing chamber with an angle of opening of the sector of 35-40 ° or more, whose axis is inclined to the surface of the radially segmented annealed / sintered material layer, taking into account the possibility of additional heating of part of the refractory insulating layer upstream of the roasted (sintered) material, whose length in the direction of its movement ensures the thermodynamic process, perpendicular to the surface of the annealed material in the form of a volumetric stream of different flame shape, consisting of individual variations based on a regulated radial sector angle in the mode of kinetic combustion process with a radiation ratio of about 50 to 55% ensuring that the conditions of the technological annealing process (sintering) of the material are met.

The pyramidal volumetric stream is formed from a variety of individual radial streams with a homogeneous flow rate exceeding the combustion rate.

The essence of the solution is also that in order to combine the process of homogenizing the media and saving energy costs for air transport, the gas supply to the mixing zone is performed at a flow velocity sufficient for ejection / entrainment / air.

The invention is also based on a device for producing a concentrated and directed heat exchange in rotary kilns consisting of a fire head, a gas burner, a shell, an interior enclosed with refractory bricks, a dust chamber, a support mechanism and a drive. a length that extends across the cooling zone. In order to reduce the air intake volumes from the surroundings of the flue gas chamber, it is equipped with a measuring device. In order to heat the gas from the furnace cooling zone, the gas burner is equipped with an external gas collector associated through a front radial-annular confuser with an internal gas collector axially disposed in the air collector and is equipped with air ejection nozzles to ensure a homogenization process. The air collector is equipped with several rows of mixing outlet nozzles, located in a single row or chess, with axes oriented radially to create a non-pyramidal volumetric flow of flame.

The essence of the solution is furthermore that in the high temperature zone, the external gas collector in the sector not occupied by the mixing outlet nozzles is provided with turbulizers in the form of solid rings imitating the mixing outlet nozzles.

In this device, the radial axes of the mixing outlet nozzles form a sector with an angle of 35 to

40 ° or more.

The use of the proposed method of directed heat exchange using the proposed burner devices provides the following advantages over existing methods:

energy sources are significantly reduced for thermodynamic annealing process increase efficiency of heat exchange processes decreases powder dust entrainment limits of use of technological equipment increases quality of use in regulation of technological regulation in heat flow control

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1 shows a rotary kiln, FIG. 2 is a section A-A of FIG. 3 is a longitudinal section of the burner apparatus (variant I), FIG. no. 4 is a sectional view along line B-B; FIG. 5 is a sectional view taken along line C-C of FIG. 6 is section D-D. In FIG. no. 7 is a longitudinal section of the burner apparatus (variant II); FIG. no. 8 is a sectional view of E-E. In FIG. no. 9 is a longitudinal section of the burner apparatus (variant III); FIG. no. 10 is a view F-F, FIG. no. 11 is a section G-G. In FIG. no. 12 is a longitudinal section of the burner apparatus (variant IV); FIG. 13 is a cross-sectional view of H-H. In FIG. no. 14 is a longitudinal section of the burner apparatus (variant V); FIG. no. 15 is a cross-section of CH-CH.

EXAMPLES

Example 1

This is a comparative example of PP 1137-2004 and UV 3698. A rotary furnace (Fig. 1) with a heat head 1, a gas burner 2, a shell 3, is internally walled with fire bricks, has a dust chamber 4, a flue gas chamber 5 and a measurable collector. 6, support mechanism 7 and drive 8.

Gas burner 2, variant I / fig. 3,4,5,6 /, has an external gas collector 9, a front radial-ring confuser 10, an internal gas collector 11 (Fig. 4), supplied with gas nozzles 12 (Fig. 6), an air collector 13 with a mixing chamber 14. mixing outlet nozzles 15.

gas supply port 16 with gas metering device 17 and shut-off valve 18, air supply port 19 with air metering device 20 and shut-off valve throttle 21. The external gas collector 9 with a circuit without mixing outlet nozzles 15 is equipped with turbulators 22. Gas the burner manifold is equipped with a branch for the lighter 23 and moves by means of a handling device 24.

In the flue gas chamber 5 / FIG. 1 / in the dust chamber 4 at the outlet of the combustion products from the rotating furnace, a measuring collector device 6 is provided with an end throttle 27. The combustion products discharged from the dust chamber 4 downstream of the dust collection system are discharged into the atmosphere.

On the inner wall of the furnace jacket 3 (FIG. 2), the annealed (sintered) material 25 is transferred, onto which the flame jet 26 formed perpendicularly from the mixing outlet nozzles 15 is directed.

The implementation of the method is given together for all examples.

Example 2

The rotary kiln is similar to Example 1. The gas burner 2 (variant II), (Fig. 7,8) has an elliptical radial-circular confuser whose nozzle base 33 is at an angle to the burner axis and mixers are located thereon. output nozzles 15.

On the inner wall of the furnace jacket 3 (FIG. 2), the annealed (sintered) material 25 is transferred, onto which the flame jet 26 formed perpendicularly from the mixing outlet nozzles 15 is directed.

Example 3

The rotary kiln is similar to Example 1. The gas burner 2 (variant III), (Fig. No. 9,10,11) has a nozzle face base 33, the plane of which is at an angle to the burner axis and is equipped with mixing outlet nozzles 15 and separating plates 30.

Example 4

The rotary kiln is similar to Example 1. The gas burner 2 (variant IV) (Figs. 12, 13) has a frontal gas collector of circular shape 34, equipped with a continuous air channel 29 and outlet ports of the mixture 12. The air channel 29 may be located axially and radially.

Example 5

The rotary kiln is similar to Example 1. The gas burner 2 (variant V), (Fig. 14,15) has a confuser 31 cut in the front part of the mixing chamber 14, equipped with mixing outlet nozzles 15.

The inner diameter of the shell 3 is formed by a drying zone "A", a heating zone - "B", a calcining zone - "C", an annealing / sintering zone / "D" and a cooling zone - "E".

The process is carried out in rotary kilns as follows.

In the gas burners 2 (variant I or II), the gas is fed through the gas supply assembly, the gas supply port 16, the shut-off flap 18, the gas metering device 17 to the external gas collector 9 and further through the front radial-annular confuser 10 to the internal gas At the same time, the air from the blower fans through the air duct system, the shut-off throttle valve 21, the air metering device 20 and the air inlet throat 19 proceed to the air collector 13 and further to the mixing chamber 14, where the gas mixing process is carried out to form a homogeneous gas-air mixture.

The prepared homogeneous mixture is fed to the combustion chamber of the sintering / roasting / D zone via the mixing outlet nozzles 15. The mixture is ignited by the lighter 23.

In the gas burner 2 / variant 111 / gas, the gas supply system, the gas supply port 16, the shut-off flap 18, the gas metering device 17 are supplied to the external gas collector 9 and further to the mixing chamber 14. At the same time, air from the blower fans via The air duct assembly, air inlet throat 19, shut-off throttle valve 21, and air metering device 20 are fed to the air collector 13 and further to the mixing chamber 14, where the mixing process takes place to form a homogeneous gas-air mixture through mixing mixing outlet nozzles. 15 is fed to the combustion space of the sintering / roasting / D zone. The mixture is ignited by the lighter 23. The uniformity of the flow pattern of the effluent mixture is stabilized by separating plates 30.

In the gas burner 2 (variants IV and V), the gas is fed through the gas supply assembly, the gas supply orifice 16, the shut-off flap 18, the gas meter 17 to the gas collector 34 and the gas nozzles 12 to the mixing chamber L4, mixing to form a homogeneous gas-air mixture. The gas-air mixture via the mixing outlet nozzles 15 is fed to the combustion space of the sintering / roasting / D zone. The mixture is ignited by the lighter 23.

In the gas burner 2 / variant V / gas from the mixing chamber 14 flows into the truncated confuser 31 and is fed through the mixing outlet nozzles 15 to the combustion space of the sintering / roasting / D zone. The mixture is ignited by the lighter 23.

The formed flue gas flows perpendicularly (variant 1) or obliquely (variants II, III, IV and V) to the placement plane of the sintered material 25 in the form of a volumetric flame of different shapes, formed by separate streams exiting the mixing outlet nozzles 15 producing high-temperature combustion products, thereby creating conditions for an efficient thermodynamic annealing / sintering / treatment process. The generated flue gas volume acting on the surface of the annealed material by the vacuum generated by the smoke extractor alters the movement path in the meridial direction, thereby generating a high temperature gas flow in the zone in which the material to be treated is increased, thereby increasing convection heat exchange efficiency.

Directing the volumetric flow to the material placement plane allows the burner devices to be removed from the high temperature zone, thus avoiding overheating and possible deformation.

In the long-term operation of the offered burner devices, depending on the temperature conditions, the front part on which the mixing outlet nozzles 15 and the mixing chamber 14 are located can also be protected by a heat-insulating refractory material.

The nozzle bases 33 may have a different inclination to the axis of the burner devices, which is determined by the technological process of the sintered material and the design of the rotary kilns.

The conical shape of the truncated canister 31 of the burner device (V variant) is used under high temperature operating conditions.

Claims (14)

PATENT CLAIMS 1. A method of producing concentrated and directed heat exchange in rotary kilns by a method of combustion of a gas in single-channel or multi-channel (ring) burners whose flame is oriented horizontally or parallel to the furnace axis (layer of annealed material) in low temperature diffusion mode. radiation, consisting of the transfer of heat intermittently in a radial direction over the furnace surface (specific heat flux), characterized in that the flame is formed in the furnace by way of combustion of a homogeneous mixture at stoichiometric gas and air balance and directed obliquely to the surface of the sintered material current with controllable radial and meridian sector angle in the mode of kinetic combustion process with a significant proportion of radiant heat, preferably 40 to 60%, ensuring the fulfillment of technological conditions during material annealing (sintering). Method according to claim 1, characterized in that the volumetric flame jet is formed from a number of individual jets with an air-gas mixture flow rate exceeding the combustion rate. Method according to claims 1 and 2, characterized in that the gas supply to the mixing zone is carried out at a flow rate sufficient to eject the air and the maximum heat exchange. Apparatus for generating a concentrated and directed heat exchange according to claims 1 to 3 in rotary kilns, consisting of a fire head, a gas burner, a shell, an interior enclosed with refractory bricks, a dust chamber, a support mechanism and a drive, characterized in that the gas burner (2) is cantilevered, with a length that extends beyond the cooling zone. Apparatus for producing a concentrated and directed heat exchange according to claims 1 to 4, characterized in that the flue gas chamber (5) is equipped with a measuring collector device (6). Apparatus for producing a concentrated and directed heat exchange according to claims 1 and 5, characterized in that the gas burner (2) is equipped with an external gas collector (9), which is connected via a front radial-annular confuser (10) to the internal gas a collector (11) mounted axially in the air collector (13). Apparatus for producing a concentrated and directed heat exchange according to claim 6, characterized in that the gas burner (2) is provided with a mixing chamber (14). Apparatus for producing a focused and directed heat exchange according to claim 6, characterized in that the front radial-annular confuser (10) has a cylindrical or elliptical shape. Apparatus for producing a concentrated and directed heat exchange according to claims 6 to 8, characterized in that the inner gas collector (11) is equipped with gas nozzles (12) for ejecting air. Apparatus for producing a concentrated and directed heat exchange according to claims 6 to 9, characterized in that the mixing chamber (14) is provided with several rows of mixing outlet nozzles (15) along the nozzle base (33), arranged regularly side by side or alternately (like a chessboard) whose axes are oriented obliquely at an angle to the sintered material (25). Apparatus for producing a concentrated and directed heat exchange according to claims 6, 7, characterized in that the gas burner (2) is provided with an external gas collector (9), an air collector (13) and a mixing chamber (14). Apparatus for generating a concentrated and directed heat exchange according to claim 11, characterized in that the front gas collector (34) is equipped with several gas nozzles (12 ') which are located in the space of the air collector (13) and the axes of which are directed parallel or at a meridian angle to the surface of the air collector (B). Apparatus for producing a concentrated and directed heat exchange according to claims 7 and 10, characterized in that the front part of the mixing chamber (14) passes into a truncated confuser (31) which is provided with a nozzle base (33), which may be flat , cylindrical or conical, directed at an angle to the axis of the rotating furnace. Apparatus for producing a concentrated and directed heat exchange according to claims 10 and 13, characterized in that the axes of the rows of mixing outlet nozzles (15) are parallel to each other or checkered and form a sector with an overall opening angle of 30 to 40 or more degrees.