How to Maintain the Combustion Temperature of the Dual Fuel Burner
How to Maintain the Combustion Temperature of the Dual Fuel Burner
Dual fuel burner is the embodiment of modern combustion technology in the industrial combustion equipment industry. The injection speed of high-temperature combustion products at its outlet can reach 100 m/s to 300 m/s. It has the technical advantages of energy saving and controllable flame momentum. It has been widely used in various heating furnaces in steel, chemical, light industry, and other industries in developed countries.
The dual fuel burner consists of an oil nozzle and an air regulator. The oil nozzle is placed on the axial line of the air conditioner, atomizes the oil into fine droplets, sprays it into the combustion chamber at a certain diffusion angle (also called atomization angle), and ignites after mixing with the air sent by the air conditioner. There are two main types of oil nozzles: pressure atomization and dual-fluid atomization. The pressure atomizing oil nozzle is composed of a splitter, a swirl plate, and an atomizing plate. The oil pressure is generally 2-3 MPa.
The oil rotates at high speed in the swirl plate, is sprayed out through the central hole, and broken into fine droplets under the action of centrifugal force. The average diameter of atomized oil droplets is less than 100 microns. The dual-flow atomizing oil nozzle uses steam or compressed air as the atomizing medium to accelerate the oil and break the atomization. The Y-type oil nozzle using steam as atomizing medium is named because the steam channel and oil channel are in a Y-shaped oblique intersection. The dual fuel burner has the advantages of a large load adjustment range and low steam consumption.
In order to achieve combustion, the dual fuel burner allows the gas and air to enter the combustion chamber respectively through a number of nozzles. The gas jet and the air jet collide one by one and mix evenly. The vector direction of the synthetic jet should be parallel to the main axis of the combustion chamber, so as to prevent one jet from penetrating the other jet, resulting in uneven mixing. In order to reduce the generation of NOx, partition combustion is adopted. The combustion temperature in the front zone is lower than that in the rear zone, and the combustion temperature at the outlet of the combustion chamber is higher.
The front zone is oxygen-poor combustion, and the rear zone increases the oxygen supply to reach the excess air coefficient at the combustion chamber outlet α= 1。 This design can not only reasonably distribute air, ensure full combustion, and prevent CO generation, but also maintain a lower combustion temperature and reduce the generation of NOx, a harmful gas. Combustion chamber wall cooling The combustion chamber is full of high-temperature combustion products, and its metal wall must have enough cooling to work safely.
In the design, the air is used to flow in the combustion chamber to absorb the heat conducted by the chamber wall and ensure that the chamber wall works within a safe temperature range. At the same time, preheating the air can promote full combustion and increase the theoretical combustion temperature. Air film is specially designed to protect the metal wall in the local high-temperature area of the combustion chamber nozzle. Due to the above design, the service life of the dual-purpose burner can reach 3 years.