（1） Diffusion burner

  Air is supplied during combustion. According to the air supply mode, it can be divided into natural air supply type and blast type.

  Natural induced draft type relies on natural pumping or diffusion to supply air, which is mostly used for civil use.

  advantage:

  a. Stable combustion without tempering;

  b. Simple structure and convenient manufacture;

  c. Simple operation, easy ignition, no need of blowing;

  d. Low pressure gas can be used, and it still works normally when the gas pressure is 200-400 PA.

  Disadvantages:

  a. The combustion heat intensity is low, the flame is large, and a large combustion chamber is required;

  b. It is easy to produce incomplete combustion and poor economy;

  c. The excess air coefficient is large and the combustion temperature is low.

  The blast diffusion burner is only supplied by the power fan, and other methods are still similar to the bairan induced draft diffusion burner.

  advantage:

  a. Compact structure and less land occupation;

  b. The adjustment range of heat load is large, and the adjustment coefficient is generally greater than 5;

  c. It can preheat gas or air, and the preheating temperature can even be close to the ignition temperature;

  d. Low gas pressure is required;

  e. It is easy to realize the mixed combustion of gas, pulverized coal and oil and gas.

  Disadvantages:

  a. Air blowing is required and electric energy is consumed;

  b. The volumetric heat intensity is lower than that of fully premixed type, the flame is long, and a large combustion chamber volume is required;

  c. It does not have the white dynamic regulation characteristics of proportional change between gas and air, and it is best to be equipped with white dynamic regulation device.

（2） Atmospheric burner

  Atmospheric burner is also called ejector premixed burner, which is widely used. The air and gas required for combustion have been mixed before gas combustion, and the combustion absorbs the diffused air at the same time. It consists of a head and an ejector. Its working principle is that the gas is ejected from the nozzle at a certain flow rate under a certain working pressure, and the primary air is inhaled by the ejector generated by the kinetic energy of the gas. After the gas and air are mixed in the ejector, it flows out from the fire holes arranged at the head for combustion. The primary air coefficient of this burner has the following advantages:

  a. The flame is shorter than diffusion combustion, with strong firepower and high combustion temperature;

  b. It can burn gas with different properties, and the combustion is complete;

  c. Low pressure gas can be used without air supply equipment;

  d. It has strong adaptability and can meet more process requirements.

  Disadvantages:

  The thermal intensity and combustion temperature of the fire hole are limited by the amount of injected air. When the thermal load is large, the structure of the porous burner is bulky.

（3） Fully premixed burner

  Complete premixing means that the air required for combustion is completely obtained by gas injection, that is, the gas and air are completely mixed before combustion.

  advantage:

  a. Complete combustion, less chemical incomplete combustion loss;

  b. There is less excess air, which will not cause excessive oxidation when used for direct heating of industrial furnace;

  c. High combustion temperature, easy to meet the requirements of high temperature process;

  d. The flame path flameless burner has high combustion intensity and high volumetric heat load, which can reduce the volume of the combustion chamber;

  e. Without fire path, it is easy to burn gas with low calorific value.

  Disadvantages:

  a. The possibility of tempering is large and the adjustment range is small. In order to prevent tempering, the head structure is complex and bulky;

  b. The burner with large heat load has a huge and bulky structure, so its single heat load generally does not exceed 2.3x103kw:

  c. High noise, especially under high pressure and high load.