How to treat solid waste through Incineration?
Municipal solid waste can be processed after collection, to lower the overall volume and weight of the material. Waste undergoes treatment, which alters its shape and facilitates handling. Additionally, it can be used to recover specific materials and heat energy for recycling or reuse.
But, how does solid waste generate energy?
In this blog, we will talk about the treatment of solid waste through incineration, as well as the energy recovered from this waste.
Operation of an Incinerator
Burning is a very efficient way to reduce the volume and weight of the solid waste. In modern incinerators, the waste is burned inside a properly constructed furnace, under extremely carefully controlled circumstances.
Treatment of solid waste through incineration
Step 1:When oxygen and the combustible waste combine, the main by-products are carbon dioxide, water vapour, and heat. An inert residue of ash, glass, metal, and other solid components known as bottom ash, is left behind after incinerating waste, which can reduce the volume of uncompacted waste by more than 90%.
Step 2:The incinerator airstream carries the gaseous by-products of incomplete combustion, as well as the finely separated particulate debris known as fly ash. Fly ash is made up of soot, dust, and cinders.
Step 3:Modern incinerators require complex emission control technologies, to collect fly ash and gaseous by-products, before they are vented into the atmosphere. These tools include electrostatic precipitators, acid gas scrubbers, and cloth baghouse filters.
Step 4:Typically, bottom ash and fly ash are mixed together and dumped in landfills. If harmful metals are identified in the ash, it must be handled as a hazardous waste.
Step 5:Municipal solid-waste incinerators are made to take in and burn waste on a constant basis. About one day's worth of waste can be stored in a deep refuse storage pit or dumping area.
Step 6:A crane with a bucket or grapple mechanism lifts the waste out of the hole. A charging grate or stoker is then used to release the material, which was dumped into a hopper and chute, above the furnace. Air can circulate around the burning material, as a result of the grate's shaking and movement of waste, through the furnace.
Step 7:Although, rotary kiln furnaces and vertical circular furnaces are also available, modern incinerators are typically constructed using a rectangular furnace. Refractory bricks, which can endure the high combustion temperatures, are used to build furnaces.
Stages of combustion
There are two stages of combustion in furnaces, which include the primary and the secondary stage.
Primary combustion causes the waste to ignite and volatilize while removing moisture.Sometimes, supplemental gas or fuel oil is burnt to initiate the primary combustion, when the waste is extremely moist.
Secondary combustion eliminates odours and reduces the amount of fly ash in the exhaust, by oxidizing the remaining unburned gases and particles.
Air must be extensively mixed with the burning waste in order to supply enough oxygen, for both primary and secondary combustion. Air is injected into the space above or supplied through apertures, beneath the grates. To achieve optimum combustion efficiency, the plant operator must establish the proportions of this, underfire air and overfire air.
Advantages and limitations of incineration
Individuals, towns, and even institutions can use this technique for managing solid waste.
Advantage:The benefit of this technology is that it can reduce waste volume by up to 20 or 30% of the initial volume.Burning waste significantly reduces the amount of combustible waste. It is a suitable strategy to reduce scavenging, in the case of off-site pits.
Limitation: It releases gaseous pollutants and poses a smoke or fire risk.
Energy restoration through incineration
Depending on the amount of paper present, the energy value of waste can be as high as one-third that of coal.
Step 1:The heat released during incineration can be captured, using a refractory-lined furnace connected to a boiler. Boilers allow the energy content of the waste to be recycled, by converting the heat of combustion into steam or hot water.
Step 2:Waste-to-energy plants are incinerators that utilize this method of heat energy recycling. A water-tube wall furnace can also be utilized for energy recovery, in place of a separate furnace and boiler. Vertical steel tubes placed together to form continuous wall sections, line the interior of such a furnace.
Step 3:To prevent heat loss, the outside of the walls are insulated. In addition, to helping to regulate combustion temperatures without the need for too much air, the water that is circulated through the tubes absorbs heat to produce steam, which lowers the cost of air pollution management.
Step 4:Waste-to-energy facilities run using either mass burning or fuel obtained from waste. A mass burning system burns all the waste without any prior preparation or treatment. Combustible waste is separated from non-combustibles, like glass and metal in a refuse-derived fuel system, before burning.
Due to the requirement for specialized machinery and controls, highly qualified technical employees, and auxiliary fuel systems, waste-to-energy systems are more expensive to construct and maintain, than standard incinerators.
The recovery of heat energy from waste is a viable solid-waste management option, from an engineering and economic point of view.
How can we assist?
The system designers at Netsol Water will be able to assess, all needs for the client, and select the most efficient, practical, modern and sustainable solid waste management technique, for municipalities, residential areas, commercial areas, as well as industries, which includes incineration as well. We can also ensure sustainable methods of solid waste collection and disposal, along with recycle and reuse.