stoker, machine for feeding coal or other solid fuel into a furnace, usually supporting the fuel during combustion. … Power for running a stoker is usually furnished by an electric motor, and control of combustion is achieved by variable speed or intermittent drive.

How does a coal 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. … The over feed delivers coal on to the top of the coals already in the furnace in the manner of a human working a shovel.

What are the classification of stoker?

Class 1 Stokers – 10 to 100 lbs (4.5 to 45 kg) coal per hour. Class 2 Stokers – 100 to 300 lbs (4.5 to 135 kg) per hour. Class 3 Stokers – 300 to 1200 lbs (135 to 540 kg) per hour. Class 4 Stokers – more than 1200 lbs (more than 540 kg) per hour.

What is a stoker grate?

: a wide endless traveling chain that feeds and supports the fuel in a boiler furnace.

How coal is pulverized?

Pieces of coal are crushed between balls or cylindrical rollers that move between two tracks or “races.” The raw coal is then fed into the pulverizer along with air heated to about 650 °F (340 °C) from the boiler. … The powdered coal from the pulverizer is directly blown to a burner in the boiler.

What is meant by overfeed and underfeed principle of coal firing?

Overfeed stoker is the type of stoker in which the coal is fed from the top and air is blown from below. Underfeed stoker is one where coal is fed from underneath and the air is fed from top.

What is stoker fired boiler?

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. … RAFAKO S.A. offers OR type steam boilers, WR type hot water boilers as well as modernisation of the existing stoker fired boilers.

What's the best coal to burn in a stove?

– Clean burning & efficient It has a high carbon content and few impurities, which means it burns far cleaner than softer, dirtier coals too. It also produces less smoke and pollutants when burnt, making it ideal for multi fuel stoves in our homes.

How does a fluidized bed boiler work?

Fluidized-bed boilers are the most common type of boiler recommended for biomass fuel, which is burned within a hot bed of inert particles, typically sand. The fuel-particle mix is suspended by an upward flow of combustion air within the bed. As velocities increase the gas/solid mix exhibits fluid-like properties.

What is the best coal to burn?

Anthracite is considered the cleanest burning coal available. It produces more heat and less smoke than other coals and is widely used in hand-fired furnaces. Some residential home heating stove systems still use anthracite, which burns longer than wood.

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What do you mean by pulverized?

1 : to reduce (as by crushing, beating, or grinding) to very small particles : atomize pulverize rock. 2 : annihilate, demolish. intransitive verb. : to become pulverized.

What is pulverized coal combustion?

Pulverised coal (PC) combustion is the most widely used technology for utility-scale power generation in the world. In PC boilers, coal is ground into fine particles (∼100 μm) and then injected with heated combustion air through a number of burners into the lower part of the furnace.

What is pulverized coal Mcq?

What is pulverised coal? … Coal which burns for long time. ANSWER: c. Coal broken into fine particles.

What is pulverized fuel firing?

We refer the process of making the fuel powder as pulverization. … This pulverized coal gets sprayed in the combustion chamber with a blow of hot air. The air used to spray the coal into the combustion chamber must get dry before entering the chamber.

What are the various types of stokers used for coal firing?

• Also called Mechanical Stokers.
• Travelling Grate Stoker.
• Chain Grate Stoker.
• Spreader Stoker.
• Vibrating Stoker.
• Underfeed Stoker.

How does a waste heat boiler work?

Waste heat boilers utilise the heat in flue gases from combustion processes or hot waste air flows from industrial processes to generate hot water or saturated steam.

How is the fuel selected in the pulverized fuel system?

Explanation: Most of the large power plants use pulverized fuel firing system since it is higher in its thermal efficiency. And selection of it mainly depends upon the size of boiler unit, type of the coal available, nature of load on the plant, load factor, cost of the fuel and availability of skilled labors.

What is in plant coal handling system?

In a coal based thermal power plant, the initial process in the power generation is “Coal Handling”. … The coal is unloaded from the point of delivery by means of wagon tippler. It is rack and pinion type. The coal is taken from the unloading site to dead storage by belt conveyors.

What are the boiler mountings and accessories?

• Main Steam Stop Valve. It is usually applied to the highest part of the shell through the flanges. …
• Auxiliary Steam Stop Valve. …
• Safety Valve. …
• Scum Blowdown Valves. …
• Salinometer valve. …
• Whistle Valve. …
• Soot Blower. …
• Automatic Feed Water Regulator.

What is a fluidized boiler?

A bubbling fluidized bed (BFB) boiler is a boiler that can also handle fuels that are difficult to pulverize or less combustible. The fuel is introduced into a mixture of sand flowing at high temperatures, allowing the fuel to be efficiently combusted.

What is FBC in boiler?

Fluidized bed combustion (FBC) is a combustion technology used to burn solid fuels. … Limestone is used to precipitate out sulfate during combustion, which also allows more efficient heat transfer from the boiler to the apparatus used to capture the heat energy (usually water tubes).

Which is hotter coal or wood?

While coal tends to burn hotter, we know enough about various kinds of wood and how to treat them to create hot-burning, consistent logs from the cultured forests grown. … These have less moisture content and tend to be denser than a natural log, so they burn hotter and longer.

Can you burn logs and coal together?

Burning coal and logs together can produce a gorgeous fire, with the aroma and long flames of a log fire, combined with the high heat output and longevity of solid fuel. Your fire can burn hotter, and for longer.

Can you burn coal on an open fire?

Can you burn smokeless coal on an open fire? More good news – of course you can. Smokeless coal, like traditional coal, is designed to be used on open fires and will burn very efficiently in a grate or fireplace. For those in smoke control areas, smokeless fuels like smokeless coal may in fact be your only option.

What is the dirtiest type of coal?

The combustion of lignite produces less heat for the amount of carbon dioxide and sulfur released than other ranks of coal. As a result, environmental advocates have characterized lignite as the most harmful coal to human health.

What is the hottest coal can burn?

Anthracite coal is the hottest burning fuel in comparison to the most com- mon ones in use.

What happens to something if you pulverize?

When you pulverize something, you break it up until it becomes dust or powder. … Pulvis is the Latin word for “dust.” When something is turned into dust, often it becomes useless.

What is a sentence for pulverized?

Pulverized sentence example To enable the soil to grow good crops the upper layer must be pulverized and weathered. The upper layer of the soil must therefore be free from weeds, finely pulverized and stocked with a readily-available supply of nutriment. Lana’s condo community was pulverized .

Where does the term pulverized come from?

The word pulverize comes from the Latin word ‘pulvis’ meaning ‘dust’ or ‘powder’, and later from ‘pulverizare’, which means to ‘reduce to powder’.

What do you understand by pulverized coal What are its advantages?

Advantages of pulverized coal It increases the efficiency of the boiler. It makes possible the use of wide variety of coal. It reduces time of raising temperature of steam. Combustion of pulverized coal can readily be adopted to automatic control.

Why is coal pulverized explain any one type of pulverized system used now a days?

Mechanically pulverizing coal into a fine powder enables it to be burned like a gas, thus allowing more efficient combustion. Transported by an air or an air/gas mixture, pulverized coal can be introduced directly into the boiler for combustion.