With the continuous development of boiler manufacturing process and technology, fuel types of boiler have also increased, such as various combustible gases, fuel oil, biomass, coal and so on.
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.
If the boiler gives overpressure indicator which affects boiler's safe operation, depressurization measures should be taken. However, please pay attention that depressurization can not be too fast. After the overpressure problem of steam boiler is solved, we should check the internal and external parts of boiler to ensure that everything is going well.
The industrial pulverized coal fired boiler is a new type of industrial coal-fired boiler focusing on pulverized coal combustion technology. The impurities are well removed when the grinding fitness of pulverized coal reaches 200 mesh. The pulverized coal is easy to be ignited and has few ash contents, which can enhance the complete combustion rate and reduce the burden of dust removal.
The characteristics of dust collector of coal-fired boiler:
1) Separating the particulate matters. The dust collector of coal-fired boiler can effectively separate the big particulate matters with ignition conditions, so as to reduce the obstruction of dust removal system and improve efficiency.
2) Reducing dust. The dust collector of coal-fired boiler can prevent the dust-contained gas from washing the bag to lower the dust concentration of dust-contained gas and extend the service life of filtering bag and pulse magnetic valve.
3) Adopting materials with high quality. The dust collector of coal-fired boiler adopts high-temperature resistant materials that can extend the service life of dust collector.
4) Adopting elastic piston ring. The mouth of filtering bag adopts elastic piston ring to ensure the leakproofness, which is firm and reliable.
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.
1.Primary air is used for transportation of fine coal particle from coal mill to boiler floor at different elevations as per requirement.
2.Primary air is used for preheating of moisturised coal in to the coal mill so that minimum energy is required for combustion of the same.
3.As we all know that only 23% oxygen is available in the air by weight. For combustion of huge quantity of coal inside the boiler very high quantity of oxygen is required. This oxygen requirement will be completed by secondary air which is supplied by FORCED DRAFT fans through ducts.
This secondary air is coming via air preheater hence its outlet temperature increases this will help in combustion and low heat input is required for combustion of coal.
Boiler efficiency is mainly depended on the amount of losses in the system. In high capacity pulverized coal fired boilers the total losses account to about 12 to 14%. Roughly 50% of the losses are governed by fuel properties like hydrogen in fuel, moisture in fuel and ambient air conditions. The other 50% losses are carbon loss and dry gas loss. The best efficiency in the boiler can be achieved if the losses are kept to the minimum. Since 50% of the losses are dependent on the fuel and ambient condition, the best efficiency can be achieved by properly tuning the other 50%, i.e. mainly carbon loss and dry gas loss.
