What is stoker firing?

What is stoker firing?

Mechanical Stoker Firing. When fuel i.e. coal is put into the steam boiler furnace by means of a mechanical stoker, the firing of boiler method is referred as mechanical stoker firing.

What is combustion system of boiler?

The boiler combustion control system is designed to maintain a proper air/fuel mixture under varying load conditions and within safe limits. The system should provide nearly complete fuel combustion as efficiently as possible. Discussions here are limited to oil and/or natural gas fired industrial boilers.

What is tertiary air in boiler?

[′tər·shē‚er·ē ′er] (mechanical engineering) Combustion air added to primary and secondary air.

What type of coal is used in stoker fired boilers?

Stoker fired boilers are the smallest units among hard coal fired boilers. They are mainly operated in local or industrial heat or heat and power generating plants….Stoker fired boilers.

How does a mechanical stoker work?

A mechanical stoker is a mechanical system that feeds solid fuel like coal, coke or anthracite into the furnace of a steam boiler. A mechanical stoker is a mechanical system that feeds solid fuel like coal, coke or anthracite into the furnace of a steam boiler.

How the air for combustion is supplied to the boiler?

Typically, two permanent combustion air openings are required in an enclosure in which fuel-burning equipment is installed. One opening should be located 12 inches from the ceiling and the other within 12 inches of the floor. This will provide air circulation in to and out of the equipment room under normal conditions.

Does combustion happen in boiler?

To generate the heat needed for steam production, boilers rely on the process of combustion, which is the burn of fuel to provide the required heat.

What is primary air and secondary air?

The primary air is heated up to about 170°C by means of a heat exchanger with the exhaust gas. The secondary air is the postcombustion air injected into the upper part of the combustion chamber and is necessary for completing the combustion process.

What is secondary air in boiler?

Secondary air is fed above the burning fuel via ring-shaped nozzles to ensure full conversion of the flue gas. Additional air is fed into the system via the fall pipe to prevent fire from backing into the fuel container.

How can we reduce coal consumption in boiler?

Today many of the boiler designers reduce this loss by recovering the heat after low temperature superheater by larger economizer and air pre-heaters. As designers go for lower and lower exit gas temperature the size of air pre-heaters go up. Tune combustion of coal to the optimal condition.

What happens inside a coal boiler?

Coal-fired plants produce electricity by burning coal in a boiler to produce steam. The steam produced, under tremendous pressure, flows into a turbine, which spins a generator to create electricity. The steam is then cooled, condensed back into water and returned to the boiler to start the process over.

What is the result if there is a lack of air in the furnace during combustion?

Lack of adequate combustion air causes improper heater operation, increased maintenance cost, and risks dangerous production of carbon monoxide gas.

Where exactly are mechanical stokers used?

Where exactly are mechanical stokers used? Explanation: Mechanical stokers are usually used in large and medium capacity plants. Mechanical stokers are used to fire almost all kinds of coal.

What is a spreader stoker boiler?

Fuel Feed. The pneumatic spreader stoker is the most common fuel feed mechanism for the Vibrating and Traveling Grates. An adjustable air swept fuel distributor is used to deposit the fuel into the furnace and on to the vibrating grate.

Do boilers need fresh air intake?

Just like our bodies need an adequate source of clean air to function properly, so does a boiler. Its peak performance depends on clean fresh air that is free from chemicals and pollutants. A boiler requires oxygen to burn the fuel it uses to create the heat needed to heat the boiler water.

How much excess air is needed for combustion?

Research has shown that 15% excess air is the optimal amount of excess air to introduce into the boiler combustion process.

How much air is needed for a combustion?

The total quantity of air supplied varies with the quantity of the fuel, rate of combustion, system of firing and the draught intensity. The excess air may approach 100 per cent but the modern practice is to use 25 to 50 per cent. The excess air is indicated by CO2% in flue gases.

Why is it necessary to expel air from a boiler?

When the liquid absorbed enough heat energy, it will change to vapour form. As thesteam is not allowed to exit, it will cause an increase in pressure and thus causing thetemperature to increase. Applications of Marcet Boiler include water boiler, gasifier, power plantand cooking utilities.

What is combustion air?

Air for Combustion Combustion is a chemical process in which, the fuel combines with oxygen gas to release energy in the form of heat and light. This heat can be used to produce electricity, run our cars and also for cooking.