What are the components of a dual fuel burner?
There are two main combustion methods for gas boilers. One is a special combustion method, where the boiler is only equipped with a gas combustion system. At this point, the advantages of gas boilers in equipment investment and operational economy can be fully reflected; The other is the mixed combustion method, equipped with two combustion systems: gas oil and gas coal. A boiler can burn gas alone, another fuel alone, or a mixture of two fuels, and is also known as a dual fuel burner. A dual fuel burner is the same burner with gas and fuel nozzles. The air regulator, burner stabilizer, ignition device, and flame monitoring device of the dual fuel burner control section must be suitable for both fuels.
Composition: The dual fuel burner mainly consists of three parts: the ordinary part, the fuel part, and the gas part. Common components: Common components include air ducts, guide vanes for controlling airflow, air branches, and fire-resistant channels. In addition, there must be a small igniter that can reliably locate the fuel and gas. The position of the flame detector should be able to detect small fires, main gas flames, and fuel (or coal) flames. Installing a larger gas supply system in a fuel burner may interfere with the mixing method of fuel combustion. The solution is to arrange the air inlet outward to the periphery of the burner.
Fuel components: mainly oil atomizer. Its function is to separate the oil flow and distribute the oil mist into the airflow in a controllable manner. The commonly used atomizers are as follows:
1. Jet atomizer
Oil enters the swirl chamber through the hole in the corner, and then sprays out in a conical shape from the annular nozzle, dispersing into droplets. The oil pressure is usually 0.35-1.4MPa, with a maximum of 7.5MPa. Under optimal operating conditions, the viscosity of the oil is approximately 15 × 1030 m2/sec. A simple jet atomizer usually affects the load regulation ratio of the burner, but it can be improved by using overflow reflux. Due to the fact that excess oil can flow back, the amount of oil entering the vortex chamber remains constant regardless of the flow rate: when the flow rate is high, a good vortex can be formed, and when the flow rate is low, a certain thickness of oil mist flow can be maintained at the outlet.
2. Steam spray auxiliary atomizer
This is an early atomizer used. Steam is directed into the oil flow, and the oil is broken into mist due to impact. Due to high steam consumption, the jet atomizer loses its attractiveness when it appears. In recent years, significant reforms have been made to this type, greatly reducing steam consumption.
Gas components:
Without exception, the gas components of dual fuel burners adopt a nozzle hole mixing type. The oil atomizer occupies the center of the stable zone of the burner, so the gas composition is limited to a certain extent. Heating with a detachable nozzle or annular cavity can reach the center; But it cannot be combined with a rotary cup oil atomizer. In other design styles, as the load increases, central supply also becomes difficult. Therefore, as mentioned above, gas is usually introduced through a ring or nozzle between the atomizer and the casing.
classification
Dual fuel burners can be divided into two categories: assembled burners (including fans and control devices, assembled by the manufacturer before leaving the factory) and on-site assembled burners (burners and controllers assembled on-site, with additional fans). The former is mostly used for fire tube boilers, while the latter is commonly used for water tube boilers. Generally speaking, dual fuel burners are developed around existing fuel burners. An oil atomizer is installed on the centerline of the burner. Gas must be introduced from the space between the oil atomizer and the casing.