How to correctly select fuel for burners

How to correctly select fuel for burners
The correct selection of fuel is an important part of burner operation, therefore it is necessary to master the characteristics of fuel, understand the combustion principle, and select fuel according to the type of fuel required by boiler design in order to achieve design requirements and expected results. The fuel used for burners can be divided into three categories based on their physical state: solid fuel, liquid fuel, and gas fuel.
1、 Solid fuel
Solid fuels include the following categories:
1. Asphalt coal: called long bituminous coal, it is gray black or black, with a dull or oily surface.
2. Anthracite coal: referred to as white coal or firewood coal, black, sometimes also gray, hard and brittle, with a glossy cross-section.
3. Poor coal: Between bituminous coal and anthracite, its volatile content is 10% to 20%, making it easier to ignite.
4. Coal gangue: This is a type of rock block in coal seams that contains combustible materials. Its ash content is high, reaching over 50%, and its heat generation is low, making it unsuitable for ignition.
5. Oil bearing shale is an oily mineral with an ash content of up to 50% to 70% and a high volatile content of up to 80% to 90%, making it easy to catch fire.
6. Wood: Compared to coal, it has lower ash content, higher volatile content, faster combustion speed, but lower heat generation.
2、 Liquid fuel
The liquid fuels commonly used in burners include heavy oil, residual oil, and light diesel. Due to the high content of carbon and hydrogen in fuel, which has a low moisture content, the heat generation is very high. Diesel is commonly used for ignition and stable combustion in small and medium-sized thermal power plants, domestic boilers, and large boilers, while heavy oil is mostly used in power plant boilers.
1. Diesel: Diesel has a low density and is a type of fuel with low viscosity, good fluidity, no need for preheating, and can be directly ignited for starting. It can be started by direct ignition and has a low sulfur content, which also reduces environmental pollution.
2. Heavy oil: Heavy oil is a general term for the heavy fraction of light distillates - gasoline, kerosene, and diesel - extracted from the petroleum refining process. The main components of heavy petroleum are carbon and hydrogen, with low ash and moisture content, and high and stable heat generation.
3. Residual oil: Residual oil is the residue generated from petroleum refining, mainly composed of high molecular weight alkanes, colloidal substances, etc., and can be directly used as fuel. Residual oil has a high viscosity and can flow when heated to a certain temperature, making its storage, transportation, and management very convenient.
3、 Gas fuel
Gas fuel is a fuel that is in a gaseous state at room temperature. Compared with various solid and liquid fuels, it has outstanding advantages such as less pollution, high heat generation, and convenient operation. It is an ideal high-quality boiler fuel. There are two types of gas fuels: natural gas fuel and artificial gas fuel.
1. Natural gas fuel: There are two types of natural gas fuels: gas field gas and oilfield associated gas. Gas field gas is a combustible gas from a pure gas field, and the accompanying gas in the oil field is a combustible gas produced during the oil extraction process. The main component of the two natural gaseous fuels mentioned above is methane, which also contains small amounts of alkanes, olefins, carbon dioxide, hydrogen sulfide, and nitrogen, and both have high heating capacities. Because natural gas is an important chemical raw material, only a few boilers near the production area can use natural gas as fuel.
2. Artificial gas fuel: There are various types of artificial gas fuel, including blast furnace gas, coke oven gas, producer gas, and liquefied petroleum gas. Except for liquefied gas, all other gases have a very low heating capacity and are low calorific value gases. Although blast furnace gas and coke oven gas have low calorific value, they are mainly used as chemical raw materials and fuel for various heating furnaces, and only a small amount are used as boiler fuel on site. Boiler gas and liquefied petroleum gas are generally not used as boiler fuel.