Coal Stoker Boiler Reliable Feeding System

A Complete Guide For Using A Coal Stoker Boiler

Does your coal-fired boiler consume more coal than normal, and the fuel costs are becoming a problem for you? Then our coal stoker boiler is the best solution to your problem. It is an automatic fuel feeding mechanism that allows you to control the amount of input fuel. Not only that, but it also provides efficient combustion.

You may have faced problems with fuel feeding, accidentally feeding more fuel than normal.  NO MORE. Our coal-fired stoker boiler helps you control the amount of fuel fed with smoke-free combustion and, hence, reduce fuel costs. For more details, below is all the information you need about a coal stoker boiler.

What is a Boiler Stoker?

A coal boiler stoker is a unit of the coal boiler that comes in fire tube and water tube boiler design. It is a mechanical system that feeds fuel into the furnace for combustion. As oxygen is the main ingredient for combustion, it provides a pathway for the air into the furnace. You can control the amount of fuel fed and the air coming in and get effective combustion.

The stoker feeds just the right amount of coal onto the grate. The coal on the grate is then ignited and burned. The burning coal gets a flow of air from below as the grate moves constantly to the other side. The fuel then gets heated and gives off hot flue gases.

When the stoker coal reaches the end of the grate, the non-combustible coal is collected below at the end. On the other hand, the hot flue gases rise and move into the mixing chamber. The process completes and the flue gases heat up the water in the tubes to generate steam.

What Is an Anthracite Coal Stoker Boiler?

An anthracite coal stoker boiler is a special type of coal stoke boiler. It uses anthracite coal instead of regular coal. This type of coal burns hottest than any other type of coal. This means using this type of coal we can produce more heat energy. Hence, we can generate more amount of steam efficiently.

Anthracite coal, also known as, hard coal, is formed by the fossil fuels that have spent the longest duration under the ground. It has endured the highest pressure and heat amount underground. Therefore, it produces more heat energy than any other type of coal.

The anthracite coal, when burned, produces a hot, blue flame. It is in the form of a shiny, cleanest, black rock that is more brittle than any other coal type. Not only does it produce more heat, but it also produces a lot less smoke than usual and burns longer than wood.

Hard coal is high-ranking coal whose temperature can rise to a temperature of 900 degrees and higher. It also produces less waste coal, called a culm. However, anthracite coal is in short supply. It is usually found in the mines in Pennsylvania.

How Many Types of Stokers Fired Boiler Are There?

Stoker-fired boilers are divided into types according to the fuel feeding method. It has 2 types:

1.     Travelling Grate Stoker

A travelling grate stoker is also called a chain grate boiler. In this type of coal stoker boiler, the grate is a chain moving around 2 pulleys at some distance. The coal is fed at one end and the combusted fuel is taken out at the other. It has a coal hopper, an ash pit, and a pathway for air.

The coal hopper puts coal on the grate chain where it is ignited and heated. The combustion of the coal happens on the chain along with its movement. The air that comes in from the pathway below helps in the combustion. This results in the production of hot flue gases. These flue gases generate steam from water.

However, when the chain reaches its other end, there may be some coal remaining that has not fully burned. That coal is collected in the ashpit at the end of the chain. The non-combustible coal is then burned again to get more heat energy.

In our chain grate coal-fired steam boiler, the coal is fed constantly to the grate. But you can control the amount of input fuel from the coal hopper, the thickness of the grate bed, and the speed of the grate. However, you should make sure that there are no big lumps of coal. It is because they will not be fully burned when they will reach the end.

2.     Spreader Stoker Boiler

The spreader stoker boiler uses suspension burning together with grate burning. The coal hopper feeds the coal into the coal stoker furnace. The small lumps of coal are burned in the suspension. But the large pieces are put on the grate. These big lumps are burned into thin pieces at high temperatures.

This type of coal stoker boiler also has an air pathway below the chain that helps in the combustion. The coal is ignited quickly, and the combustion rate is increased. The air is injected into the furnace using a system of the rotor.

This coal boiler also allows controlling the amount of input fuel. It also can feed the fuel constantly in an even pattern. That’s why spread stoke boiler is usually favored rather than boiler chain grate stoker.

What is the Meaning of Overfeed and Underfeed Principle in Coal Boiler Stoker?

Overfeed coal stoker boiler

As the name suggests, in overfeed coal boiler stoker, the fuel is fed over the top of the furnace. This method of fuel feeding is used in both chain grate and spreader stoker boilers. The coal is poured from the above opposite from where the air is injected.

The air coming from below goes through the burning coal and gets heated. The oxygen then oxidizes the coke of the burning of the coal to emit CO2. The oxidation rate of carbon depends on the input air.

The grate in the furnace is moved constantly while combusting the coal. The fuel is fed to the front side from above the furnace and moved towards the rear end. At the rear end, the coal that has not burned is collected in the ashpit. The air incoming from the bottom of the grate reacts with the fuel and gives off gases such as N2, CO2, and O2.

Although this coal boiler is not appropriate for big lumps of coal, it can be useful when changing the amount of input. Its operation is cost-effective, and the incoming air also helps in cooling the ash.

Underfeed coal stoker boiler

It is a mechanism that feeds the fuel from the bottom of the furnace and moves upward to meet the already burning coal. The air enters from the same direction as the coal to aid the combustion. This method is the most convenient for small steam coal boilers.

The feed coal is entered into the furnace from below the burning coal. This is achieved by using adjustable retorts. Retorts are tubes that contain raw coal. The raw coal meets the air and then is advanced upwards in the furnace to burn. Note that the reaction with the coke is similar to that of the overfeed method.

Despite its high installation costs and big size, its load and thermal efficiency are significantly higher. It can do well with a variety of coal types. The grate can clean itself automatically. Not only does it provide smoke-free combustion, but it is also appropriate for variable load input. Moreover, its grate and retort tubes can hold themselves at high temperatures.

Conclusion

Yongxing manufactured coal stoker boilers are the most thermal efficient coal boilers. Our coal stoker boiler allows you to control the amount of input fuel that reduces fuel costs significantly. The amount of heat generated is increased when anthracite coal is used as input for the boiler. This type of coal produces more amount of heat than any other type of coal.

The chain grate stoker feeds the fuel at the front of the grate. While it is under combustion, the chain is moved constantly to the other end. At the rear end, the remaining coal is collected in the ashpit. The spreader stoker uses suspensions to burn little pieces and uses a grate bed for big lumps of coal.

The coal stoker boiler comes with two methods of fuel feeding. One is in which the fuel is poured from the top of the furnace on the grate. The air comes in from below the moving chain and aids in the combustion process. It is called overfeed principle. The other is underfeed principle. In it, the fuel is entered from the same path as the air i.e., below the grate. And, the input is advanced upwards for combustion in the furnace.