Detailed description of various gas burners
The gas burner is a gas combustion device, which enables gas and air to enter the combustion area separately or mixed to achieve stable combustion. There are many types of gas burners. The following describes several burners that are widely used in industrial boilers in the form of gas supply.
1、 Natural air supply burner.
Circular or rectangular burners can be selected according to the shape of the furnace. Low-pressure gas flows out through the fire hole in the pipe and is premixed with air. It is a diffusion combustion method with primary air coefficient, so it is also called diffusion burner.
The burner has stable combustion, convenient operation and simple structure, which can meet the requirements of 300~400Pa low pressure gas. However, the excessive air coefficient in the furnace is large, the smoke heat loss and the incomplete combustion heat loss of the gas are large, and the combustion rate is low. It can only be used in small capacity boilers.
2、 Injection burner.
There are many kinds of burners, which can be divided into partial air premixing method and air premixing flameless combustion method according to their combustion mode. The injection medium used can be air or gas with certain pressure. The former requires air blowing device.
1. Atmospheric injection burner.
This kind of burner gas enters the ejector at a certain flow rate from the nozzle, and then injects primary air at the ejector's mouth, and then the two gases mix into the burner head, flows out from the fire hole, and burns in the form of a spontaneous flame.
The burner is also only used for small boilers and is applicable to all kinds of low pressure gas. It does not need an air blower, but it has a large heat load and a huge and bulky structure.
2. Air injection burner.
When the air pressure head is 5000~600OPa, a negative pressure is formed through the nozzle through the ejector necking, and the low-pressure gas is sucked from the four pipe holes. The two gases are mixed in the mixing pipe to form a uniform gaseous mixture, which flows to the outlet of the fire hole, and then burns in the stable flue connected with the outlet.
This burner is a flameless burner with complete combustion air premixing. The excess air coefficient at the furnace outlet is small, and the combustion intensity is high. However, it needs to be equipped with an air blowing device, which consumes a lot of electricity. It is suitable for positive pressure furnaces with air preheaters.
3、 Blast burner.
The blast burner is generally composed of a distributor, a gas distributor and a flue. There are many kinds of burners, and the commonly used ones are the swirl type and the flat flow type.
This type of burner is basically the same as the air distributor of oil-fired burner. There are two types of gas diverters: single-tube and multi-pipe. Its structure is simple, and the flame characteristics generated during combustion are similar to the general swirl and direct-current oil-fired burner. The burner has strong mixing, perfect combustion, small excess air coefficient, but greater resistance.
4、 Imported gas burner.
It mainly includes three parts, namely gas system, air system and control system.
The function of the gas system is to provide gas for combustion. It is mainly composed of filter, pressure regulator, pressure switch, safety valve, solenoid valve, flow regulating valve, distributor, etc.
The role of the air system is to provide a certain amount and pressure for combustion. It is mainly composed of casing, fan impeller, damper, flame stabilizer (air distribution plate), combustion head, shaft, sliding rod, damper dial, pressure tap, combustion head adjusting screw, etc.
The function of the control system is to make the burner run according to the specified procedure. It is mainly composed of wiring terminal, threading hole, control box, contactor, thermal relay, ignition transformer, ignition electrode, motor (servo motor), photoelectric tube, flame sensor, etc.