The exhaust gas heat loss of coal-fired boiler is caused by the flue gas removed by final stage heat exchanger. The flue gas will take away a part of heat, mainly including the heat taken away by dry flue gas and the sensible heat with water vapor in the flue gas. What’s more, if the combustible gas in the coal-fired boiler is not completely burned, there will be heat loss as well. Therefore, this kind of heat loss mainly depends on the content of incomplete combustion products in the exhaust smoke.
Once the flameout of gas-fired or oil-fired boiler is confirmed, the boiler should be shut down for inspection and maintenance in time according to the operating regulations. Only after the inspection and test are completed, the boiler can continue to be used.
Coal is one of the main fuels used by boilers, especially the coal-fired boiler. In order to reduce the production costs, we need to know whether the coal-fired boiler saves coal in operation.
The fuel of a gas-fired boiler is gas such as natural gas, city gas, biogas and liquefied gas, etc. What kind of fuel the boiler burns is decided by an equipment called a burner. The boiler equipped with a gas-fired burner is called a gas-fired boiler. There are three methods of gas-fired boiler combustion as per technical characteristics of how the gas and air mix.
1. Diffusion combustion:
Gas and air mutually diffuse at the gas nozzle and are burning. The advantages are burning stably and with simple burner structure. However, the heated area is easy to be carbonized due to long flame, which is easy to produce incomplete combustion.
2. Premixed combustion:
A part of air and gas are premixed before combustion (coefficient of primary air surplus is between 0.2-0.8), and then being burned. The advantages are clear combustion flame, enhanced combustion, and high thermal efficiency.
The condensing boiler burns carbon-based fuel with oxygen in order to produce steam and carbon dioxide. The gases that escape this process (through a chimney) as exhaust are called flue gases. The major advantage is that they offer up to a 90% improvement in terms of efficiency when compared to standard gas boilers. Overall, condensing boilers are considered much more efficient in contrast to non-condensing gas boilers, a major consideration for any business running on a budget.
The causes of coal erosion as distinct from all the other types of erosion are many but from a theoretical point of view are simply high velocity particles impacting and rubbing along the surface of the tubes.
The boiler designer minimises this by providing a volume in the furnace and a direction of travel of the coal such that it is burned before it can touch the tubes. This can be defeated by increasing the velocity reducing the combustibility or increasing the mass flow. All of these parameters occur if you reduce the calorific value of the fuel or overload the boiler. If you had no erosion before changing your fuel that is the cause. If you have never had design fuel you dont know if it would have eroded anyway. If it would the cause will be a different reason such as arodynamic flows and aiming of the burner or size of the tartget fireball centre. This is a serious problem and should be dealt with by an experienced expert.
