Oxidizing flame means that when oxygen andacetyleneWhen the mixing ratio is greater than 1.2, all combustible components in the fueloxygenAchieve when sufficientComplete combustion, a smokeless fuel product without free C, CO, H2, CH4 and other combustible componentsflame。Suitable for welding coppermanganese steelAnd other metal materials.[1]
When the fuel is burning, it needs a certain amount of oxygen, which is mainly used to support combustion. At the same time, the amount of oxygen supply also directly affects the nature of the flame atmosphere.Fuel combustion is the reaction of the combustible components carbon, hydrogen, sulfur and other hydrocarbons with oxygen to generate CO2, H2O, SO2, etc.The amount of oxygen required calculated according to these reaction equations of complete combustion is called theoretical oxygen amount.In the actual combustion, in order to ensure the complete combustion of fuel, the amount of oxygen supplied should be more than the theoretical amount of oxygen, and the excess oxygen is called excess oxygen.The ratio between the actual oxygen supply and the theoretical oxygen demand is called the oxygen excess coefficient, which is expressed by the formula: a=actual air supply/theoretical air demand
Nature of atmosphere
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The ratio between the actual oxygen supply and the theoretical oxygen demand is called the oxygen excess coefficient, which is expressed by the formula: a=actual air supply/theoretical air demand
a＞1，Oxidizing atmosphere
a=1，Neutral atmosphere
a＜1，Reducing atmosphere
Neutral atmosphere only exists in theory, which is difficult to achieve in actual production practice.
actual production
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In ceramics, glass, cement, metallurgy and other industries, the value of a is an important basis for judging whether the flame nature and fuel combustion are normal.When the value of a is too large, too much oxygen supply (usually air supply) will cause the temperature of the combustion chamber to drop. If the value of a is too small, it will not ensure that the fuel is completely fuel, which will cause fuel waste and change the nature of the flame.
When firing ceramic products, the nature of flame will have a significant impact on the color and performance of products.For example, the traditional building bricks in our country, when the firing is near the end, consciously reduce the amount of combustion supporting air, so that there are incomplete combustion of reducing gas products such as CO and H2 in the flame, and the high price of red in the brick under high temperatureFerric oxideRestored to low price cyanFerrous oxide, bricks are also green.And inred brickDuring the firing process, the oxide flame is always kept burning, and the red ferric oxide in the brick is not reduced, so the burnt product is red.
stayceramic glaze The color of many colored glazes is also related to the nature of flame, the most typical of which is the precious copper red glaze.It is called copper red glaze when fired in a good reducing flame, but it is green when fired in an oxidizing flame, which is called copper green glaze.
In gas welding and cutting, when the oxygen supply is insufficient, the combustion will emit black smoke. Only when the ratio of oxygen to acetylene is greater than 1.2, acetylene can be completely burned. At this time, the flame is clear blue, without black smoke, belonging to the oxidation flame, and the firing temperature can be up to more than 2000 degrees Celsius.
When using coal gas or liquefied gas in daily life, if the flame during combustion is yellow and has black smoke, the combustion at this time is incomplete fuel, which will cause fuel waste. The correct approach is to open the air valve of the burner, increase the supply of oxygen (air), so that the fuel is normal and the flame is blue. At this time, the flame is oxidizing flame.
Oxidation flame of welding
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The temperature of the oxidation flame can reach 3100 ^ - 3400 0C.Due to the large supply of oxygen, the whole flame is oxidizing.When welding ordinary carbon steel, the use of oxidation flame will cause the oxidation of molten metal and the burning loss of alloy elements, so that the weldmetallic oxideAnd air entrainment increases and enhances the boiling phenomenon of the molten pool, thus greatly reducing the welding quality.Therefore, oxidation flame must not be used for welding of general materials.However, when welding brass and tin bronze, a slight oxidizing flame is used, and the oxide film generated is covered on the surface of the molten pool, which can prevent the evaporation of zinc and tin.Because the temperature of the oxidizing flame is very high, the oxidizing flame is often used to improve the efficiency when the flame is heated.Oxidation flame is usually used in gas cutting.
