Goren called oxidation reaction proceeds at a high rate, which is accompanied by heat in large quantities and, as a rule, a bright glow, which we call fire.The process of studying the physical chemistry of combustion, which usually referred to burning all exothermic processes having a self-accelerating reaction.Such self-acceleration may be due to increase in temperature (t. E. Have a thermal mechanism), or accumulation of the active particles (having a diffusion nature).
combustion reaction is a visual feature - the presence of high temperatures (fire), limited space, where there is a big part of the transformation of the starting materials (fuel) in the combustion products.This process is accompanied by the release of large amounts of thermal energy.To start the reaction (flame appearance) required to expend an amount of energy on the ignition, then the process proceeds spontaneously.Its speed is dependent on the chemical properties of the substances participating in the reaction, as well as the dynamic processes during combustion.The combustion reaction has certain characteristics, the most important of which - the calorific value of the mixture and that the temperature (called adiabatic), which theoretically could be achieved by the complete combustion without heat.
By aggregation of the oxidizer and fuel combustion process can be assigned to one of three types.The combustion reaction may be:
- homogeneous if the fuel and oxidizer (pre-mixed) are in a gaseous state,
- heterogeneous, in which solid or liquid fuel reacts with the oxidizing gas,
- reaction of combustion of gunpowder and explosives.
homogeneous combustion is the most simple, has a constant speed, which depends on the composition and molecular heat conduction mixture, temperature and pressure.
heterogeneous combustion is most common in nature, and in vitro.Its speed is dependent on the specific conditions of the combustion process and the physical characteristics of the ingredients.In the liquid fuel in the combustion rate is greatly influenced by the rate of evaporation from the solid - gasification rate.For example, in coal combustion process produces two stages.In the first of them (in the case of a relatively slow heating), emit volatile components of the substance (coal), to the second burns coke.
Combustion gases (for example, the burning of ethane) has its own characteristics.The gaseous medium flame can spread to a vast distance.It can move by gas at a subsonic speed, and the property of not only a gaseous medium, but also a mixture of fine liquid and solid combustible particles mixed with an oxidant.In order to ensure stable combustion in such cases, the special design of the furnace device.
consequences that causes the combustion reaction in a gaseous medium, are of two kinds.First - a turbulence in gas flow, leading to a sharp increase in process speed.Emerging with acoustic flow disturbance may lead to the next stage - the emergence of shock wave leading to detonation of the mixture.Daylight detonation combustion step depends not only on the intrinsic properties of the gas, but also on the size of the system and propagation parameters.
combustion fuel used in the art and industry.The main task is to maximize combustion efficiency (ie. E. Optimization of heat) for a specified period.Use burning, for example, in mining - methods development of various minerals based on the use of fuel.But under certain conditions, natural and geological phenomenon of combustion can be a factor, carrying a serious danger.The real danger, for example, is a process of spontaneous combustion of peat, leading to the emergence of endogenous fires.
