RU2367846C2 - Method of gas combustion and burner for method implementation - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention concerns thermal power industry, particularly methods and devices of gas fuel combustion in infrared burners. Method of gas fuel combustion in infrared irradiation burner involves preparation of homogenous gas fuel and air mix in ejector, mix heating in distribution chamber and in perforated ceramic nozzle channels to ignition temperature, burning on nozzle surface and in the space between nozzle and metal mesh, generation of stripped gas and air mix with air excess factor α=1.3-1.5. Gas and air mix is tripped either by air supply to the burner ejector by fan, or by increasing rated gas pressure before burner in 6-7 times.

EFFECT: enhanced efficiency factor, reduced hazardous substance content in combustion products.

4 cl, 3 dwg

Description

The invention relates to a power system, and in particular to methods and devices for flameless combustion of hydrocarbon gas fuel on the surface of a ceramic nozzle of infrared burners.

A known method of flameless combustion of gas fuel, carried out in infrared burners containing an ejector, a perforated ceramic nozzle and a metal mesh, including creating a homogeneous air-gas mixture in the burner ejector with an excess air coefficient α = 1.02-1.07, heating the mixture in a distribution chamber and in the channels of a perforated ceramic nozzle to the ignition temperature, the mixture burns on the surface of the nozzle and in the space between the nozzle and the metal mesh [1, p.31-32, Fig. 13].

The specified method is characterized by a high content of harmful substances in the products of gas combustion and significant convective heat losses.

Closest to the claimed invention is an infrared emitter and a method for carrying out the combustion process of hydrocarbon gas fuel, described in the patent of the Russian Federation No. 21110015, IPC F23D 14/18 [2]. The present invention provides a method implemented in an infrared emitter, which consists of coaxially arranged and alternating non-corrugated and corrugated cylinders activated by a ceramic catalyst. The specified method of burning gas involves creating a homogeneous air-gas mixture, supplying the mixture to the internal cavity of the emitter, heating the mixture to the ignition temperature, burning the mixture inside the volumetric ceramic nozzle when moving from the center to the surface, and radially removing combustion products.

The disadvantages of this invention are the complexity of the manufacture of ceramics activated by the catalyst, and the low value of the radiant efficiency (COP).

The problem solved by the invention is the technical result - an increase in radiant efficiency and a decrease in the content of harmful substances in the combustion products of infrared gas burners.

The technical result is achieved by the fact that a depleted gas-air mixture is created in the burner ejector with a coefficient of excess air α = 1.3-1.5.

The depletion of the air-gas mixture is carried out by supplying a fan to the ejector of the air burner.

The depletion of the air-gas mixture is carried out by increasing 6-7 times the nominal gas pressure in front of the burner.

The burner for implementing the method is additionally equipped with a screen made of heat-resistant glass with a hole in the center for the removal of combustion products.

The proposed method of gas combustion, in comparison with analogues, provides an increase in the surface temperature of the emitter and, therefore, radiant efficiency, as well as a decrease in the content of harmful substances in the combustion products.

In the proposed method, a gas-air mixture of a different composition is created in the burner ejector than in the prototype and analogues with a coefficient α = 1.3-1.5. This is achieved by supplying additional air to the burner ejector with a fan or by increasing 6-7 times the nominal gas pressure in front of the burner. As a result, the speed of the mixture in the channels of the ceramic nozzle increases, heat transfer is intensified, and the probability of flame penetration decreases.

A heat-resistant glass screen prevents the diffusion of ambient air to the surface of the ceramic emitter and reduces convective heat loss. In addition, the screen creates hydraulic resistance to the outflow of combustion products, and this helps to increase the contact time of the combustion products with the surface of the nozzle, which leads to an increase in the surface temperature of ceramic tiles and to a more complete afterburning of products of incomplete combustion.

The burner device (longitudinal section) for implementing the proposed method of burning gas is shown in Fig.1.

The burner comprises a housing 1, a nozzle 2, a fan 3, an ejector 4, a distribution chamber 5, a divider 6, ceramic tiles 7, a metal mesh 8, a screen 9 with an opening 10. The screen 9 is made of heat-resistant glass transparent to infrared radiation.

The burner operates as follows. A gas jet flowing out of the nozzle 2 draws in atmospheric air into the ejector 4. A homogeneous air-gas mixture is created in the ejector with the required coefficient of excess air, namely α = 1.3-1.5. The depletion of the mixture is achieved by supplying additional air with a fan or through the use of high pressure gas. The mixture passes through the distribution chamber 5, the divider 6 and through the channels of the tiles 7 comes to their surface. In the distribution chamber 5 and in the channels of the tiles 7, the mixture is heated to the ignition temperature. The combustion of the mixture occurs in a thin layer on the surface of the nozzle and in the space between the nozzle and the metal mesh 8. The combustion products are discharged through the opening 10. A significant part of the heat of combustion is transferred to the ceramic tiles 7, the surface of which is heated and becomes a powerful source of infrared radiation.

The application of the proposed invention in economic activity will increase the efficiency of technological processes in industry, reduce the amount of gas consumed, improve radiant heating and reduce the emission of harmful substances in heated rooms and the environment.

An example of a specific implementation and implementation of the method

To implement the claimed method, the burner GII-1.85 "Zvezdochka" produced by OJSC "Kazan gas equipment plant - VESTA" was used. The radiating nozzle of the burner contains three ceramic tiles with a channel diameter of 1 mm. A metal mesh is placed above the nozzle at a distance of 10 mm.

The emitting nozzles were closed with a cap made of heat-resistant glass with a hole in the center for the removal of combustion products. To supply excess air, the burner was equipped with a micro-fan.

The experiments were carried out at the laboratory bench. While maintaining a constant pressure of the liquefied gas in front of the burner, the coefficient α varied from 0.8 to 2.0. The gas pressure varied stepwise from 1800 to 3600 Pa (from 180 to 360 mm water column). The surface temperature of the nozzle was determined using an infrared sensor. During the experiment, the coefficient α, the surface temperature of the emitter, and the composition of the combustion products were recorded.

According to the results of the experiments, the dependences shown in Figs. 2 and 3 are constructed. Fig. 2 shows the dependence of the nozzle surface temperature on the coefficient α and gas pressure (P), and Fig. 3 shows the content of carbon monoxide (CO) and hydrocarbons in the combustion products (СН) and oxygen (О ₂ ) depending on the coefficient α at a nominal gas pressure of 3000 Pa.

From figure 2 it is seen that with an increase in the coefficient α, the surface temperature of the nozzle increases and reaches a maximum at α = 1.3-1.5. And then it decreases at all studied values of the gas pressure in front of the burner. With an increase in gas pressure and, consequently, gas consumption and burner power, the surface temperature increases from 880 ° C at P = 1800 Pa to 1130 ° C at P = 3600 Pa.

According to the dependency graphs of figure 3, it should be noted that with an increase in the coefficient α to 1.0-1.1, the concentration of CO and CH in the combustion products decreases sharply. Then, at α> 1.2, their concentrations remain at a minimum level, and are 0.2–0.3% and 50–80 ppm, respectively. And only the oxygen content is gradually increasing. The yield of nitrogen oxides does not exceed 50-60 ppm.

Forced air supply with a fan complicates the design of the burner. An alternative is to use medium pressure gas. The experiments at a gas pressure of 10, 20, and 30 kPa gave similar results and thereby confirmed the possibility of using this way of depletion of the gas-air mixture.

Thus, experimentally established the effectiveness of the proposed method for burning gas fuel in an infrared burner. Compared with analogs, an increase in the temperature of the emitter and, therefore, radiant efficiency by 10-20%, a decrease in the content of harmful substances in the products of combustion - carbon monoxide (CO) by 50-70%, hydrocarbons (CH) by 20-30% was recorded.

The proposed burner for implementing the inventive method can be used for heating large industrial, public and agricultural buildings, drying and local heating.

Information sources

1. Bogomolov A.I., Wigdorchik D.Ya., Mayevsky M.A. Gas burners of infrared radiation and their application. - M .: Stroyizdat, 1967 .-- 254 p.

2. RF patent №2110015, IPC F23D 14/18. Anikeev V.I., Kuzin N.A., Gudkov A.V. Infrared emitter, a method for carrying out the combustion process of hydrocarbon gas fuel and a method for preparing complex ceramics activated by a catalyst. BI No. 12, 1998.

Claims (4)

1. A method of burning gas fuel in an infrared burner, including creating a homogeneous gas-air mixture in an ejector, heating the mixture in the distribution chamber and in the channels of the perforated ceramic nozzle to the ignition temperature, burning on the surface of the nozzle and in the space between the nozzle and the metal mesh, characterized in that a depleted gas-air mixture is created in the burner ejector with a coefficient of excess air α = 1.3-1.5. 2. The method according to claim 1, characterized in that the depletion of the air-gas mixture is carried out by supplying a fan to the ejector of the air burner. 3. The method according to claim 1, characterized in that the depletion of the air-gas mixture is carried out by increasing 6-7 times the nominal gas pressure in front of the burner. 4. A burner containing an ejector, perforated ceramic nozzles and a metal mesh, characterized in that it is additionally equipped with a screen made of heat-resistant glass with a hole in the center for the removal of combustion products.

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