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THERMAL DEVICES, DEVICES FOR HEATING AIR AND OTHER GAS-FUEL MEDIA AND THEIR APPLICATION
INVENTION
Patent of the Russian Federation RU2272219

RADIATION BURNER

RADIATION BURNER

The name of the inventor: Shmelev Vladimir Mikhailovich
The name of the patent holder: N.N. Semenov RAS (RU); Shmelev Vladimir Mikhailovich
Address for correspondence: 119991, Moscow, ul. Kosygina, 4, Institute of Chemical Physics, Russian Academy of Sciences, Patent Department
Date of commencement of the patent: 2004.10.14

The invention relates to heat power engineering, namely to radiation burners, it can be used for domestic and industrial needs in various heat power plants, in domestic and household gas stoves, heaters, dryers, furnaces and improves the ecological and operational characteristics of the burner, since it ensures complete combustion Fuel and a sharp decrease in the amount of CO in combustion products. The radiation burner comprises a housing, an injector in the form of a gas nozzle with a mixing tube and a ceramic perforated radiating nozzle made in the form of cavities with a transverse dimension and a depth of at least 10 mm, the ceramic perforated radiating nozzle being designed as a single two-stage cavity or a plurality of two- Honeycomb or in the form of a system of two-stage concentric annular cavities, the diameter or transverse dimension of the exit section of the upper stage not more than 1.5 times greater than the diameter or transverse dimension of the outlet section of the lower stage, and the height of the upper stage is 0.05-0.95 of the total depth Cavity, with the perforated bottom and walls of the lower stage of the cavity.

DESCRIPTION OF THE INVENTION

The invention relates to heat power engineering, namely to radiation burners, and can be used for domestic and industrial needs in various heat power plants, in household and household gas stoves, heaters, dryers, ovens.

An industrial burner is known (US Patent No. 5,174,444, dated December 29, 1992) with low emissions of CO and NOx into the atmosphere, which consists of a fuel and oxidizer mixing unit, a perforated ceramic plate (nozzle) over which gas is combusted, and a light screen screen , Which, heated by the flame of the burner, increases the temperature of the radiating surface of the nozzle and promotes the oxidation of CO in CO 2 , reducing CO emissions into the atmosphere, while the screen is installed above the burner plate at a distance that depends on the length of the flame.

The disadvantage of such a burner is insufficient reduction of carbon monoxide emission, weak mechanical strength of the light screen screen and its coating in the form of a special ceramic foam, and a significant complication in the manufacture of the burner.

A radiation burner is known (RU No. 2066023, F 23 D 14/12, 1994) containing a housing with a perforated cover playing the role of a radiation shield equipped with a radiating nozzle in the output section of the housing.

The disadvantage of such a burner is the high requirements for the thermal and oxidative resistance of the cover-screen, which determine the need to use expensive grades of nickel steels. The presence of a screen cover increases the hydraulic resistance, degrades the stability of combustion at low fuel pressures, and does not reduce the carbon monoxide in the combustion products below 0.008%.

An industrial burner is known for burning mixed gas mixtures of increased thermal power with a radiator temperature of 1473-1723 K and with a ceramic packing having a number of rectangular slits made in the form of a flat sudden expansion (AK Rodin, Gas Radiant Heating., Leningrad: Nedra, 1987 , С.21-23, рис.2.4).

The disadvantage of such a slot burner is the occurrence of a flame slip when the specific heat load decreases due to the excessive width of the channels and the realization in the space between the partitions at high heat load of the flare combustion regime with an increased temperature in the combustion zone leading to an increase in nitrogen oxides in the combustion products. Another disadvantage is the weak mechanical strength of long thin partitions between the channels.

The closest solution to the technical essence and the result achieved is an infrared burner comprising a housing, an injector in the form of a gas nozzle with a mixing tube and a ceramic perforated radiating nozzle configured to additionally perform screen and reflector functions, for which it is performed in a volumetric configuration in the form Cavities with a transverse dimension and depth of at least 10 mm, with only the bottom of the cavities or only walls or walls and bottom perforated (RF patent No. 2151957, cl. F 23 D 14/12, 2000) (prototype).

Combustion of the fuel-air mixture in such a burner occurs mainly in the near-surface zone inside the cavities of the ceramic perforated radiating nozzle, and afterburning of the unburned components - far from the walls in the volume of cavities of the ceramic perforated radiating nozzle.

The disadvantage of the prototype burner is the unevenness of the afterburning of the unburned constituents along the height of the cavity and even the complete absence of afterburning of a portion of unburned constituents formed near the exit section of the cavity.

The aim of the invention is to create a highly efficient radiation burner with enhanced environmental and operational characteristics that will ensure complete combustion of fuel and a sharp decrease in the amount of CO in combustion products, an increase in the stability of combustion in a wide range of gas pressure changes, an increase in radiation efficiency and, Application of a radiation burner.

The solution of the task is achieved by the proposed radiation burner comprising a housing, an injector in the form of a gas nozzle with a mixing tube and a ceramic perforated radiating nozzle configured as a single two-stage cavity or a plurality of two-stage honeycombs or as a system of two-stage concentric annular cavities with transverse size and depth Not less than 10 mm, the diameter or transverse dimension of the exit section of the upper stage of the cavity not more than 1.5 times greater than the diameter or transverse dimension of the output section of the lower stage of the cavity, and the height of the upper stage is 0.05-0.95 of the total depth of the cavity, And the bottom and walls of the lower stage of the cavity are perforated.

The holes in the lower perforated stage of a single two-stage cavity or a plurality of two-stage honeycombs can be made at an angle of 0 to 90 ° to the radius of the inner surface of the cavity (drawn to the opening).

The lower perforated stage of the cavity can be made of porous ceramics.

The lower stage of the cavity can be made in the form of a set of annular elements made of ceramic or metal with a gap between them no more than 2 mm and with the possibility of performing an additional function of the gas swirler.

The design features of the burner provide incineration of the gas mixture in the cavities under conditions of strong radiation feedback from the walls of the nozzle cavities and exclude the mixing of cold ambient air into the combustion zone, as a result of which the temperature of the inner surface of the radiating cavities of the nozzle increases, that is, the radiation efficiency increases, and the two- Guarantees complete combustion of unburned gas constituents in the recirculation zone in the second stage of the cavity, due to the low hydraulic resistance due to the lack of a screen grid (the function of the screen is performed by the nozzle itself) and the recirculation of part of the gas increases the stability of combustion in a wide range of fuel pressure changes. In addition, thanks to the volumetric design of the ceramic nozzle, the specific power of the burner increases from the unit output section. Improving the environmental and operational characteristics of the proposed burner allows us to expand the scope of its application.

The gas mixture is delivered through apertures in a perforated nozzle, made tangentially (90 °) to the radius of the inner surface of the cavity or at any angle to the radius in the range of 0 to 90 ° (the radius is drawn to the hole), or tangential movement of the gas mixture in the gaps Nozzle, made in the form of a set of ring elements, increases the residence time of the combustion products inside the cavities, which leads to a more complete completion of the chemical combustion reactions.

The design of the lower perforated stage of cavity made of porous ceramics greatly simplifies and reduces the cost of manufacturing the burners.

The device of the proposed radiation burner is shown in the accompanying drawing (FIG. 1), which shows a longitudinal section of the burner with a volumetric ceramic nozzle.

RADIATION BURNER

The radiation burner (FIG. 1) consists of a housing 1, an injector in the form of a gas nozzle 2 with a mixing tube 3, a ceramic radiating nozzle 4 made in a two-stage volumetric configuration in the form of a plurality of two-stage honeycomb hollows with a perforated bottom and walls of the lower stage of the cavity 5 and Upper stage of cavity 6 of larger diameter with non-perforated walls.

The radiating nozzle 4, made in the form of a system of two-stage concentric annular elements with a gap between them, consists of the lower stage 5 and the upper stage of a larger diameter 6 of the nozzle 4 (Fig. 2).

The burner works as follows. Gas, flowing through the nozzle 2 and the mixing tube 3, injects the required amount of air, forming a gas-air mixture of the desired composition, which then flows through the perforated lower stage of the ceramic nozzle (through its channels at an angle of 0 to 90 ° to the radius of the inner surface of the cavity) and burns Inside the cavities near the inner surface. The surface of the nozzle cavities is heated to a high temperature, being a source of powerful infrared radiation. Part of the radiation is locked in concave cavities, absorbed by the radiating walls and increases their temperature to 1000-1200 ° C, which in turn leads to an increase in the radiation flux from the surface. Then, the combustion products pass through the upper stage of the ceramic nozzle, made in the form of an unperforated part of the cavity of a larger diameter. During the flow of combustion products from the lower stage of the cavity to the upper one, with a sharp change in the diameter of the section near the walls in the lower part of the upper stage, recirculation currents (vortices) appear, as a result of which the residence time of the wall layers of the combustion products at high temperature increases. This leads to the afterburning of unburned constituents, which are formed, especially when burning gas in the upper part of the perforated nozzle stage. The concave shape and the large depth of the nozzle cavities make it difficult to mix the cold ambient air into the chemical reaction zone, and maintaining the high temperature of the products inside both cavity steps, but not exceeding 1200 ° C, at a distance of about 10 mm from the surface ensures complete chemical reactions, including Oxidation of CO in CO 2 , and does not lead to the formation of an appreciable amount of nitrogen oxides.

In the design of a gas burner, when the gas mixture is supplied through holes in a perforated nozzle stage, tangles made tangentially or at an angle to the radius of the inner surface of the cavity (angle change from 0 to 90 °) or in a gas burner design with a nozzle, the perforated part of which is made in In the form of a set of annular elements made of ceramic or metal with a gap between them of not more than 2 mm and with the possibility of performing an additional function of the gas swirler, the combustion products inside the radiation cavity move along spiral trajectories, the time of their stay inside the cavity increases, and this leads to a more complete completion of the chemical Reactions within the cavity.

The selected parameters of the ceramic nozzle are determined as follows. The depth of the concave cavities of the ceramic nozzle, including the length of the lower perforated and upper non-perforated parts of the nozzle, not less than 10 mm, comparable with the extent of the CO burn-out zone, ensures complete completeness of chemical reactions in conditions that exclude their "hardening" due to elimination of cold ambient air penetration Zone of chemical reaction. The large transverse cavity size, not less than 10 mm, makes it possible to perforate the bottom and walls of the nozzle cavities with a large number of cylindrical channels of small diameter (less than 2 mm) and determine an insignificant hydraulic resistance to the flow of combustion products, which increases the stability of combustion in a wide range of fuel consumption.

The design of the volumetric nozzle with cavities, the perforated part of which is made in the form of a set of ring elements with a gap between them (see FIG. 2), has an additional advantage associated with manufacturability and ease of manufacture, it allows to solve the task and achieve the indicated technical result.

Experimental studies of the proposed radiation burner implemented as a prototype and made in the form of a concave cavity of a hexagonal constant cross section with a total depth of 50 mm and a transverse dimension of a lower stage of 55 mm with flat perforated radiating walls 40 mm in height and an unperforated upper stage with a transverse dimension of 65 mm and Height of 10 mm, showed that such a burner has high energy and environmental parameters. The combustion of the gas was carried out with the stable operation of the burner in a wide range of gas flow rates, up to extremely low at a specific heat output of up to 30-50 kW / m 2 , while a high surface temperature was reached - up to 1200 ° C in the normal operation mode with a radiation efficiency of 60- 65% and a record low concentration of CO in combustion products - less than 0.0001%.

Similar results were obtained with gas combustion using a radiating nozzle, the perforated part of which is made in the form of a set of ring elements made of metal with a gap between them of 0.8 mm.

Thus, all the components of the burner are aimed at the solution of the task and the achievement of this technical result - increasing the ecological and operational characteristics of the burner by ensuring complete combustion of fuel and a sharp decrease in the amount of CO, increasing the stability of combustion in a wide range of fuel pressure changes, increasing its radiation efficiency, But also to ensure the manufacturability and simplicity of the manufacture of the burner.

CLAIM

A radiation burner comprising a housing, an injector in the form of a gas nozzle with a mixing tube and a ceramic perforated radiating nozzle configured as a single two-stage cavity or a plurality of two-stage honeycombs or as a system of two-stage concentric annular cavities with a transverse size and depth Less than 10 mm, the diameter or transverse dimension of the exit section of the upper stage of the cavity not more than 1.5 times, exceeds the diameter or transverse dimension of the output section of the lower stage of the cavity, and the height of the upper stage is 0.05-0.95 of the total depth of the cavity, The bottom and walls of the lower stage of the cavity are perforated.

2. Radiation burner according to claim 1, characterized in that the holes in the lower perforated stage of one two-stage cavity or a plurality of two-stage honeycombs are formed at an angle of 0 to 90 ° to the radius of the inner surface of the cavity.

3. Radiation burner according to claim 1, characterized in that the lower perforated stage of the cavity is made of a porous ceramic.

4. Radiation burner according to claim 1, characterized in that the lower perforated stage of the cavity is made in the form of a set of annular elements made of ceramic or metal with a gap between them no more than 2 mm and with the possibility of performing an additional function of the gas swirler.

print version
Date of publication 29.01.2007gg