What is the burning rate and how can I increase it?

The combustion rate reflects the amount of combustibles burned per unit of time. Since combustion is a complex physicochemical process, the speed of combustion depends on:1

the rate at which combustibles react with oxygen; 2.The speed at which oxygen and combustibles are mixed in contact. The former is called the chemical reaction rate, also known as the chemical condition; The latter is called the physical mixing velocity, also known as the physical condition.

The speed of the chemical reaction is directly proportional to the pressure, temperature, and concentration of the reaction substance in the reaction space. For example, in the actual combustion of a boiler, the main factor affecting the speed of chemical reaction is the temperature in the furnace, the furnace temperature is high, and the chemical reaction speed is fast. In addition to the speed of the chemical reaction, the rate of combustion also depends on the speed at which the air flow transports oxygen to the surface of the carbon particles, i.e., the speed of physical mixing.

The physical mixing speed depends on the relative velocity of the air and the fuel, the turbulence of the airflow, the diffusion velocity, etc. The speed of chemical reaction and the speed of physical mixing are related to each other, and both play a role in restricting the combustion rate. For example, there should be a high rate of chemical reaction at high temperatures, but if the physical mixing rate is low, the oxygen concentration decreases, and the combustible material does not get enough oxygen**, and the combustion rate will inevitably decrease.

Therefore, a faster combustion rate can only be obtained when the chemical and physical conditions are relatively adaptable.

In solid fuel combustion, the amount of reduction in the mass of solids burned per unit time is known as the combustion rate.

There are many solid fuels mixed in the calcination and pellets of cement vertical kiln, so the pellets can be regarded as having a high ash content.

of solid fuels. The combustion rate of this solid fuel determines the yield quality and thermal efficiency of the vertical kiln.

The combustion rate of the fuel in the vertical kiln depends on the temperature, the size of the pellet, the particle size of the fuel and the amount of combustion in the pellet, and the diffusion rate of oxygen to the surface of the fuel. High temperature, pellets and anthracite.

Among the particles, the high concentration of anthracite in the pellet and the rapid diffusion rate of oxygen to the surface of the fuel can increase the combustion rate of this ash solid fuel - pellet.

The rate of combustion is the amount of combustible substances burned per unit area and per unit time.

Gas combustion rate.

The rate at which a gas burns varies depending on the composition of the substance. Simple gas combustion requires only processes such as thermal oxidation, such as hydrogen; Complex gases need to go through the process of heating, decomposition, oxidation and other processes before they can start combustion, such as natural gas, acetylene, etc. Simple gases burn faster than complex gases.

In gas combustion, the rate of diffusion combustion depends on the rate of diffusion of the gas, whereas the rate of mixed combustion depends on the rate of chemical reaction itself. Generally, the mixing combustion rate is higher than the diffusion combustion rate, so the combustion performance of the gas is often measured by the flame propagation rate.

The flame propagation velocity has different values when tested in pipes with different pipe diameters, generally increasing with the increase of pipe diameter, and when a certain diameter is reached, the velocity does not increase;Similarly, the flame propagation velocity decreases as the pipe diameter decreases, and when a certain small pipe diameter is reached, the flame no longer propagates. The diameter of the tube when the flame in the tube is no longer propagating is called the limit diameter. If the diameter of the combustion outlet is less than the limit diameter, the flame will not propagate into the tube.

The rate at which the liquid burns.

The combustion rate of the liquid depends on the evaporation of the liquid, that is, the first evaporation and then the combustion, and the combustion rate is related to the initial temperature of the liquid, the diameter of the storage tank, the level of the liquid in the tank, the moisture content of the liquid in the liquid and other factors. The higher the initial temperature, the faster the combustion;The tank burns faster when the liquid level is low than when the liquid level is high;What doesn't contain water burns faster than what doesn't contain water. After the liquid is ignited, the flame spreads along the surface of the liquid, and its velocity can reach.

In order to continue the liquid combustion, a large amount of heat must be input to the liquid to evaporate the surface layer, and the flame heats the liquid by radiation, so the propagation rate of the flame along the liquid surface is determined not only by the initial temperature, heat capacity, and latent heat of evaporation, but also by the radiation capacity of the flame. For example, when benzene is 16 at the initial temperature, the combustion rate is. In addition, wind speed also has a great influence on the speed at which flames spread.

Solids combustion rate.

The combustion rate of solid substances is generally smaller than that of combustible gases and liquids. And the combustion rate of different solids is also very different. Such as naphthalene and its derivatives, phosphorus trisulfide, rosin, etc., are solid at room temperature, and the combustion process is heated melting, evaporation, vaporization, decomposition and oxidation, and combustion, which is generally slow.

Nitro compounds and nitrocellulose products contain unstable groups, and the combustion is decomposable, more intense, and fast.

1. Choose an engine type with higher efficiency potential, such as steam turbine, diesel engine, gasoline engine, and jet engine.

2. If the type has been selected, choose a more technologically advanced model and a better quality fuel.

3. If you are improving the existing machine by yourself, such as the upstairs, optimize the fuel, optimize the combustible gas replenishment method, increase the temperature of the combustion chamber, make the fuel burn as fully as possible, and reduce the residue; Then do a good job of thermal insulation of the combustion chamber to reduce heat dissipation, and heat dissipation can also be used for other purposes; Improve the air tightness of the combustion chamber and reduce the abnormal loss of reaction gas; Improve the linkage performance of the mechanism and reduce the mechanical loss in the process of energy output.

One is to increase the contact area between the fuel and oxygen, and the other is to have enough air or oxygen.

Liquefy or vaporize the fuel to reduce heat dissipation, and the right amount of oxygen, otherwise it will take away the heat.

The fuel particles are fine enough to provide enough oxygen.

Summary. The main factor influencing the rate of fire burning is the nature of the combustible mixture. The speed of flame propagation is related to the physicochemical properties of the gas.

The flame propagation velocity of the fast-combustible gas is large, and the flame propagation velocity of the slow-combustible gas is small. The gas with a large thermal conductivity has a fast internal heat transfer, so the flame propagates quickly, such as the soil has the largest thermal conductivity, so the flame propagation speed is the fastest.

The main factor influencing the burning rate of the fire is the nature of the mixture. The speed of flame propagation is related to the physicochemical properties of the gas. The flame propagation velocity of the fast-combustible gas is large, and the flame propagation velocity of the slow-combustible gas is small.

The heat transfer inside the gas with a large thermal conductivity is fast, so the flame propagation is also fast, such as the thermal conductivity of the soil is the largest, so the flame propagation speed is the fastest.

It is related to factors such as oxygen, combustibles, wind, temperature, humidity and so on.

Question 1: What is combustion efficiency? Combustion Efficiency (CE): Refers to the percentage of carbon dioxide concentration in the exhaust gas at the flue outlet and the sum of the carbon dioxide and carbon monoxide concentrations.

Question 2: What is the thermal efficiency equal? The meaning of thermal efficiency is:

For a specific thermal energy conversion device, the ratio of its effective output energy to input energy is a dimensionless index, which is generally expressed as a percentage. The common ones are power generation units, boiler units, engine units, etc.

Thermal efficiency is equal to useful work divided by total work, and the actual absorbed heat divided by the total heat.

Question 3: What is the relationship between thermal efficiency and calorific value or degree of combustion From your question, you can only choose the degree of combustion, the calorific value is an inherent property of the substance, and the degree of combustion is limited by the accompanying conditions.

Thank you.

Question 4: What is the thermal efficiency of a gas stove Thermal efficiency is the ratio of the heat absorbed and utilized by the heating water of your gas appliance to the theoretical calorific capacity of the gas consumed after combustion. It is generally a decimal of less than 1. Because the heat spreads into the surrounding space, it cannot be fully absorbed by the water.

Question 5: What is the combustion efficiency of coal burned by the boiler of thermal power plants? The maximum energy of the fluidized bed is 97%, and the pulverized coal is also.

Boiler efficiency is based on the premise of assuming a certain combustion efficiency, which can be calculated according to the heating surface, also known as the calculation efficiency of the boiler, and the actual efficiency also depends on the quality of operation.

Boiler thermal efficiency refers to the percentage of heat absorbed by steam and water in the boiler to the heat input from fuel. When calculated according to the reverse equilibrium method: thermal efficiency = 100 - q2 - q3 - q4 - q5 - q6 boiler combustion efficiency refers to the ratio of the heat released by the fuel in combustion to the heat possessed by the fuel, and its value is approximately = 100-q3-q4

Question 6: What is the thermal efficiency and heat load of gas appliances? Thermal efficiency refers to how much (%) can be used by burning a certain amount of gas, that is, the rate of fuel utilization, which is commonly known as energy saving or not energy saving; Heat load refers to how much heat can be generated in a certain amount of time.

In layman's terms, it is not fast to heat.

The main factors affecting the rate of solid combustion are as follows:

The factors influencing the combustion rate of solids include the chemical composition, chemical structure, wind direction and speed of solid materials, water content and specific surface area of solid substances.

The combustion process of solid combustibles is much more complex than that of gaseous and liquid combustibles, and there are many influencing factors.

Influencing factors. Once solid combustibles are ignited and burned, they will spread along the surface of the combustible. The speed of spread is related to the environment due to the characteristics of cryptopants and materials, and its size determines the speed of fire development.

1) The lower the melting point and thermal decomposition temperature of the solid, the faster the combustion rate and the faster the fire spreads.

2) The oxygen concentration in the external environment increases, and the flame propagation speed accelerates.

3) An increase in wind speed is also good for the propagation of flames, but excessive wind speed will blow out the flames. The air pressure increases, increasing the rate of chemical reactions and accelerating the flame propagation.

For the same material, under the same external conditions, the flame propagation and propagation speed along the horizontal, inclined and vertical directions of the material are also different. In the absence of wind, the shape of the flame is basically symmetrical, and the entrained air flow around the flame is also symmetrical due to the rise of the flame, and the flame will spread in all directions against the direction of the air flow. The heat transfer mode of the flame to the unburned area of the material surface is mainly thermal radiation, but the convective heat transfer at the root of the flame is dominant.

When there is wind, the flame is tilted in the direction of the wind. The thermal radiation between the flame and the surface of the material is no longer symmetrical. On the upwind side, the flame propagates in the direction of the wind.

However, the radiation angle coefficient is small, the radiant heat is negligible, and the gas phase heat conduction is the main mode of heat transfer in the car, so the flame propagation speed is very slow or even impossible to propagate. On the downwind side, the heat transfer between the flame and the surface of the material is mainly thermal radiation and convective heat transfer, and the radiation angle coefficient is large, so the flame propagation speed is faster.

The spread of flaky solid combustible fires.

Once paper, curtains, curtains and other flake solids catch fire, the fire spread law has significant characteristics compared with ordinary solids. This is because this solid combustible material has a large area, small thickness, and small heat capacity, and it heats up quickly after heating. Moreover, the spread of this kind of fire is relatively fast, and it has a great impact on the development of the whole fire process, so it should be the main object of early fire extinguishing.

In particular, combustible materials such as curtains and curtains are usually placed vertically. Due to the thermal buoyancy of the fire process, the fire spreads faster.