Steam boiler can perform combustion with some fuels classification. Each fuel has advantage and disadvantage for use. One of fuel that usually used for combustion is natural gas. Combustion of natural gas can give higher efficiency than combustion of liquid or solid. But in the process, use natural gas for combustion is easy for explode and more dangerous, so the construction of steam boiler should consider safety and impact to high cost construction.
Hydrocarbons ethane and methane is the mainly content of natural gas. They can be danger because ethane and methane can burn easily. In the combustion system of steam boiler, to perform combustion need some requirement as follow; air supply, mixing of air and fuel, proper temperature and time. Natural gas can be burned with a blue flame or without a visible flame.
If one of requirement of combustion is not provided such as does not supply enough air and mixing composition of air and gas will lead to produce carbon monoxide, it is very poisonous and danger for human. So control of fuel and air is important to avoid incomplete combustion. Control range composition by volume of gas (based on hydrocarbon content) and air is the actual step to avoid burn explosively and violently. The danger range of gas is between 8% – 13 % and the safe range of gas is between 0 – 7 %.
A lot of concentrations of vapor exist, at certain range vapor will be diffused in the air and can lead to explosion. An explosion can occur if the mixture is contacted with open flame or spark. Therefore to prevent that concentration, it will be important to install safety shut of valve and perform purging at after and before combustion.