Also, the Municipal Solid Waste (MSW) has become environmental hazard due to lack of treatment and utilization. Many efforts are being made by the researchers to address these issues with natural renewable resources, such as Municipal Solid Waste (MSW) as a cleaner source of energy. But its poor properties like low energy density, high moisture content, irregular shape and size, and heterogeneity make it difficult to use in its natural form.
Waste-to-Coal plants turn municipal solid waste (MSW), often called garbage or trash, into high calorific value of charcoal by means of “Torrefaction”. This charcoal can be converted into coal pellets and can be used in boilers along with regular coal to produce steam which is used to generate electricity. Also, it can be used in various type of industries in place of conventional coal or wood.
Municipal Solid Waste (MSW) contain some energy-rich materials such as paper, plastics, yard waste, and products made from wood. These materials are extracted from MSW by removing the Inert material and converted into Segregated Combustible Fraction (SCF) The Torrefaction process of SCF is conducted in a preset temperature range. It is carried out under preset temperature & pressure zones along with oxygen deficient conditions. depending on the feedstock type and the desired characteristics of the output product. The output of this process is a product with increased energy density, decreased oxygen to carbon ratio, improved grindability, and improved handling and storage properties. The output is Bio-coal which has similar properties to fossil carbon. The gases produced during this process is utilized in heating the Reactor to make is self sustained system without taking any auxiliary fuel for heating during normal operation. NTPC has already completed trial by putting a pilot plant. Now MBPL is setting up 800 TPD plant in Varanasi on commercial operation basis.
This type of plant is sometimes called a Waste-to-coal, municipal waste conversion, energy recovery, or resource recovery plant.
Waste-to-coal is being increasingly looked at as an alternate against conventional coal which is Fossil fuel. The biggest advantage is utilization of Waste into conversion of energy without depleting the carbon loaded fossil fuel. Thus, saving natural resources and solving the Eco-Social issue by disposing Municipal Waste.
Segregated MaterialsIn Waste-to-Coal plant, the municipal solid waste is brought to the facility for segregation of Inert material. Segregated combustible fraction (SCF) fed into the reactor as and when required.
Torrefaction TechnologyWaste to Coal facility is based on Torrefaction technology, which is a thermal treatment of SCF within preset range as required for the process. It is carried out Oxygen Deficient Condition.
The CharcoalThe Charcoal that is discharged is further cleaned using a sieve. The pure char is mixed with exacting proportions of binder & water in a mixer. The mixture is fed into a pelletizing machine. The moist pellets are dried in a continuous tray dryer. Once the pellets reach the desired moisture level, it is discharged & stored in a Pellet silo. Delivery trucks are loaded from the Silo.
Waste arrives in receiving shed by means of tipper truck/compactor from the Municipal Corporation / other agencies and weight of loaded truck is measured in the weigh bridge. The waste unloading area is also provided with sufficient air handling unit for ventilation and odor control to maintain fresh and fragranced air. Waste pit area is provided to with adequate storage capacity. This facility is completely closed with negative draft provided by means of the ventilation system. Waste pit area also equipped with methane sensor to sense accumulation of flammable gas at pit area.
Waste pit area equipped with waste grab crane which is mounted over an EOT crane for mixing and picking the waste in the pit. Grab cranes carry the waste to feeding hopper. It is operated automatically for the feed cycle which controlled through a PLC system. Waste conversion to char facility consist of Shredder, Segregated combustible fraction (SCF) hopper and reactor with its auxiliaries. The combustible that is discharged by the shredder is called Segregated combustible fraction (SCF).
SCF from Shredder is fed to the reactor drum. Reactor converts the SCF to charcoal. After torrefaction of the SCF, the charcoal must be cooled before it is discharged. Dry charcoal pellets help boiler to attain better efficiency while co-firing. Charcoal conversion to pellets consists of Sieve, mixer, and pelletizer.
Waste arrives in receiving shed by means of tipper truck/compactor from the Municipal Corporation / other agencies and weight of loaded truck is measured in the weigh bridge. The waste unloading area is also provided with sufficient air handling unit for ventilation and odor control to maintain fresh and fragranced air. Waste pit area is provided to with adequate storage capacity. This facility is completely closed with negative draft provided by means of the ventilation system. Waste pit area also equipped with methane sensor to sense accumulation of flammable gas at pit area.
Bio-coal is carbon-neutral as it is derived from Municipal Solid Waste (MSW) without any mining of fossil fuels. Using 1 kg of bio-coal as solid fuel, by replacing fossil coal brings to a reduction of approx.
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