What are the main pollutants of gas-fired boiler?

gas-fired boiler is a kind of boiler equipment that uses natural gas as the main fuel. Compared with coal-fired boiler and biomass-fired boiler, gas-fired boiler has a very high degree of environmental protection, and it is vigorously promoted. However, some substances harmful to the environment will still be produced, and relevant departments have formulated strict emission standards. Here, ZOZEN Boiler introduces what the main pollutants of gas boiler are and how to deal with them.

What are the main pollutants of gas-fired boiler?

If you want to know what the main pollutants of gas boilers are, you must first know the composition of natural gas. Natural gas is composed of alkanes, the main component of which is methane, and a small amount of ethane, propane and butane, in addition to hydrogen sulfide, nitrogen and water gas.

The waste gas from natural gas combustion in boiler mainly contains carbon dioxide, water, carbon monoxide, sulfur dioxide, nitric oxide, nitrogen dioxide, etc. Among them, sulfur dioxide, nitrogen oxides, smoke and dust are the main pollutants of gas-fired boilers, which are the important influencing factors of air pollution.

1. Nitrogen oxides

As many users know, nitrogen oxides are the emission substances to be monitored during the operation of gas-fired boilers, and the emission standards are 30, 50 and 80 mg/nm³. When purchasing boilers, users should choose to meet the local emission standards.

2. Sulphur dioxide

It is stipulated by the state that the ex-factory content of natural gas should not exceed 0.01%, and the natural gas boiler adopts advanced burners to ensure that the fuel burns sufficiently, and the sulfur dioxide emission can meet the emission standard without treatment. It is stipulated in the Emission standard of air pollutants for coal-burning oil-burning gas-fired boiler that the sulfur dioxide of natural gas boiler should not exceed 100mg/Nm³, or even lower.

3. Smoke and dust

Natural gas is a clean energy source, gas fuel, which burns more fully and produces less smoke and dust, but it can't be said that it doesn't. It is stipulated in the Emission standard of air pollutants for coal-burning oil-burning gas-fired boiler that the smoke of natural gas boiler should not exceed 10mg/Nm³.

Ultra-low nitrogen emission from ZOZEN gas boiler

Knowing what the main pollutants of gas-fired boilers are, it is necessary to eliminate them one by one. Flue dust and sulfur dioxide can be fully burned by high-efficiency burners to meet the emission standards, while nitrogen oxides need to be treated by advanced low-nitrogen combustion technology.

1. Low nitrogen burner+flue gas recirculation technology (FGR)

About 10%~30% of the flue gas (the temperature is about 170℃) from the environmental protection tail of the gas boiler is sucked into the air inlet of the combustion engine through the flue gas pipeline, mixed with combustion-supporting air, and then enters the furnace. Thereby reducing the temperature of the combustion area, simultaneously reducing the oxygen concentration in the combustion area, and finally reducing the generation amount of thermal NOx, so that the emission of nitrogen oxides in the tail flue gas of the boiler is lower than 30mg/m³.

2. Stratified combustion technology:

Phase I, about 70%-80% of the air volume is sent from the burner, so that the fuel can be burned under the anoxic and rich combustion conditions, and the combustion speed and temperature of the fuel can be reduced;

Phase II: the remaining part (20%) of the combustion air is sent in the form of secondary air, so that the fuel enters the excess air area (as the second stage) and burns out. At this time, although there is a large amount of air, because the flame temperature is low, more NOx will not be generated in phase II, so the emission of NOx can be reduced.

ZOZEN gas-fired boiler also has the advantages of high thermal efficiency and convenient operation. The advanced PLC computer control system has automatic technologies such as automatic continuous water feeding, programmed ignition, proportional pressure and temperature control combustion, and various safety interlock protections, which not only reduces the operation and maintenance cost for enterprises, but also through strict monitoring, ZOZEN gas boiler can achieve low nitrogen emission, which meets the environmental protection requirements of gas boiler, and achieves a double harvest of economic and environmental benefits for users.

No matter what the main pollutants of gas-fired boilers are, as a professional boiler manufacturer, ZOZEN Boiler will give full play to its own advantages, provide users with energy-saving gas-fired boiler products that meet the requirements of environmental protection, and achieve high-quality development.