Do you know the dc pulverized coal burner?Date: 2019-07-24 Views:
Pulverized coal burner is the main component of combustion equipment of coal - burning boiler.Its role is to transfer fuel and air to the furnace, organization of fuel and air in time, full mixing, ensure that the fuel into the furnace as soon as possible, stable fire, rapid, complete combustion.
When pulverized coal is burned, in order to reduce the heat needed for ignition, it is necessary to heat the pulverized coal rapidly so that it can reach the ignition temperature as soon as possible, so as to realize ignition as soon as possible.Therefore, the amount of air needed for pulverized coal combustion is divided into primary and secondary air.The function of the primary wind is to feed the coal into the furnace and supply the oxygen needed for the combustion of volatiles in the initial ignition stage.The secondary air is mixed with the pulverized coal air stream after it catches fire, providing the oxygen needed by coke and residual volatilization to ensure the complete combustion of pulverized coal.
Dc burners usually consist of a series of rectangular nozzles.After the pulverized coal air and hot air are ejected from the nozzle, the dc jet is formed.
Type of dc pulverized coal burner:
There are two types of arrangement of primary and secondary air spouts of dc pulverized coal burners.One kind is suitable for burning coal which is easy to catch fire, such as bituminous coal, lean coal with higher volatile content, and lignite.The primary and secondary air nozzles of such burners are usually arranged alternately, and the center distance between the two adjacent nozzles is small.
Because the coal powder carried by the primary wind is easy to catch fire, it is hoped that the coal powder caught fire in the primary wind and the hot air emitted from the adjacent secondary air nozzle can be mixed timely and quickly.In this way, the lack of air at the base of the flame does not cause incomplete combustion or slow combustion.Therefore, the distribution of air volume of secondary air vents arranged along the height is nearly uniform.
Graded air direct flow burner with primary air concentration
Suitable for burning coal which is difficult to catch fire, such as lean coal, anthracite coal or inferior coal.The characteristic of this burner is that several primary air vents are arranged together, and the center distance of primary and secondary air vents is larger.
Because the coal powder carried in the primary wind is difficult to catch fire, the mixing of the primary and secondary wind is too early, which will reduce the flame temperature and cause the fire instability.In order to maintain the stable ignition of pulverized coal flame, it is hoped to delay the mixing of pulverized coal airflow and secondary wind, so the secondary wind is further divided into two batches and sent into the pulverized coal airflow after the fire. This kind of air distribution is called fractional air distribution.
The purpose of fractional air distribution is to feed adequate amount of air to ensure the stable ignition and complete combustion of pulverized coal at different stages of the combustion process.
(1) characteristics of centralized arrangement of primary wind
A. Maintain relatively high pulverized coal concentration in the ignition area to reduce the heat;
B. Heat release from combustion is relatively concentrated, which keeps the burning area at high temperature and is suitable for coal burning;
C. The coal dust airflow is more rigid, and it is not easy to stick to the wall obliquely.At the same time, the ability to absorb high temperature flue gas is strengthened.
(2) the problem of centralized arrangement of primary wind
High concentration of pulverized coal in the ignition area may cause insufficient oxygen supply in the ignition area and delay the combustion process.The area near the primary air nozzle is a high temperature area, and the nozzle is easy to deform, so that the air velocity distribution near the nozzle outlet is uneven, and the air and coal are prone to stratification.In order to eliminate this phenomenon, the primary wind is sometimes divided into multiple small jets, so as to enhance the turbulence of airflow and improve the stability of ignition.
Near the primary air nozzle is in high temperature, and the primary wind speed is low, the nozzle is easy to burn out.In order to cool the primary air nozzle, sandwich wind or perimeter wind can be installed on the primary air nozzle.Of course, sandwich wind or boundary wind can also enhance the ability of the primary atmosphere to absorb high-temperature smoke.
No matter what kind of burner, the ultimate goal is to make coal better and cleaner combustion.But the dc burner is to create a power field in the furnace, through the way of cutting circle to rotate the air in the furnace, attract the surrounding high temperature flue gas to participate in the combustion.The cyclone burner is designed to disturb the air, so that the pulverized coal air is fully mixed, which is conducive to combustion.