Incinerators Articles

Incinerator : Device For Combustion

Incineration is a process which reduces the volume of solid waste. There are different types of incinerators using different processes to destroy the waste.

Without reacting with air no incineration can take place hence different types of incinerators want maximum contact with air. This contact speed up the process of incineration. Different types of incinerators undergo same process but in different manner.

Structure
Differnt incinerators have different Structure. There are two major opening in the incinerator. One is meant for receiving waste and other for the exhaust gas. The bottom of the incinerators consist of two plates. One plate collects the waste and the other plates collects the ash which is produced from the burning waste. The major constituents of the incinerators are Combustion zonest. These zones lie above the plates. Normally there are three combustion zones, the Main combustion zone, Ember combustion zone and Final combustion zone. Apart from these there are two other zones Primary combustion chamber and secondary combustion chamber along with another plate known as the straightening plate.

Functions of Various Zone

Primary Chamber
Primary chamber is a zone where combustion takes place that is very similar to thermal decomposition.

Secondary Chamber
In secondry chamber, for complete combustion, combustion gas is retained enough time by circular flow.

Ember Combustion Zone
In this zone high temperature air (more than 300ºC) is blown into it. This provides enough time for complete combustion.

Final Combustion Zone
Here final combustion takes place. All unburned particle and Dioxin in ash are combusted completely.

Incineration Process
Incineration takes place in the following steps:

Drying
In this step the water is evaporated through an endothermic reaction. Drying is essential before burning. The drying helps in saving the heat energy which can be otherwise wasted in absorbing the water from wet waste or materials. In this no oxygen is required however, energy is essential.

Pyrolysis
Pyrolysis is an endothermic reaction which breaks the organic compounds into smaller molecules. This is a reaction that takes place towards the end of the process of incineration. It is a partial oxidation of the organic portion.

Gasification
Gasification takes place towards the end of the process of incineration. It oxidises the organic compound partially. Since it is an exothermic reaction it requires oxygen.

Combustion
Combustion is a last reaction of complete oxidation of the organic binding. This results in the creation of CO₂ and H₂O. Since this is an exothermic reaction it requires oxygen.

By Products
Ash is one of the by products of the incineration process. This arise from the waste. As ash is non combustible it simply gets stored in the incinerator. Ash is classified into two types: Fly ash and bottom ash There are two types of ash: Fly ash and Bottom ash. Fly ash consist of lighter particles that float up from the grate whereas bottom ash is a partly combusted residue that accumulates on the grate.

Advantages

• Incinerator reduces the discharge of waste in our environment.
• It destroys Combustible Toxins like dioxin through a process called combustion.
• The process helps in eliminating disease causing contaminated materials like as radioactive soil, concrete, asphalt, wood, plastics etc.

Energy saving systems
Incinerators help in saving energy through two process:

Steam dryer system
In this system seam dryer is used in order to dry the sludge cake indirectly. It is the gas boiler through which the steam is generated. Through this system lot of energy is saved because it is simple and easy and of course helping the environment.

Hot-air dryer system
This system uses hot air to dry the sludge cake. Hot air is pre-heated into heat-exchangers. Because of a rotary kiln dryer, this hot air then goes against the sludge cake. During the entire drying operation, this rotary kiln dryer remains in contact with the sludge cake. As no boiler is necessary for the hot-air dryer system, the maintenance is easy.