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Write Short notes on Biomass stoves

Biomass : Wood-fuelled heating systems, also called biomass systems,
burn wood pellets, chips or logs to provide warmth in a single room or
to power central heating and hot water boilers. A stove burns logs or
pellets to heat a single room - and may be fitted with a back boiler to
provide water heating as well.

How do biomass stove works

Modern wood-burning stoves are a huge improvement on the open fire
for room heating. They convert 70 per cent of the fuel into useful
heat.Biomass boilers can replace oil or gas boilers to heat hot water and
radiators (or under floor heating). They burn logs, wood chips, wood
pellets or other forms of biomass.
A biomass cook stove is heated by burning wood, charcoal, animal dung
or crop residue. Cook stoves are commonly used for cooking and
heating food in rural households. Nearly half of the world's population,
approximately 3 billion people, use solid fuels such as coal, wood,
animal dung, and crop residues for their domestic energy needs. Among
those who use indoor cooking stoves, the poorest families living in rural
areas most frequently use solid fuels, where it continues to be relied on
by up to 90% of households.
Households in developing countries consume significantly less energy
than those in developed countries; however, over 50% of the energy is
for cooking food. The average rural family spends 20% or more of its
income purchasing wood or charcoal for cooking. The urban poor also
frequently spend a significant portion of their income on the purchase of
wood or charcoal. Deforestation and erosion often result from harvesting
wood for cooking fuel. The main goal of most improved cooking stoves
is to reduce the pressure placed on local forests by reducing the amount
of wood the stoves consume, and to reduce the negative health impacts
associated with exposure to toxic smoke from traditional stoves.
TYPES
Improved chulhas, or cookstoves, come in two main types: fixed mud
chulhas (with a chimney) and portable metal chulhas (without a
chimney).

Fixed Mud Chulhas (with Chimney):

These are typically made of mud and brick and are designed to be
stationary, often with a chimney to exhaust smoke.

Portable Metal Chulhas (without Chimney):

These are usually made of metal and are designed for portability, often
lacking a chimney.

SOME EXOTIC DESIGNS

Exotic designs of improved chulhas (cookstoves) focus on enhancing
efficiency, reducing smoke, and improving cooking outcomes. These
designs often incorporate features like multiple burners, secondary air
inlets, and advanced combustion chambers. Some exotic chulhas might
feature unique shapes or materials for improved heat distribution and
fuel efficiency.
Here's a more detailed look at some exotic designs:
1. Dual-Pot Chulha:
Design:
This design features two separate cooking compartments or "pots,"
allowing users to cook multiple dishes simultaneously or use different
pots for different cooking styles.

Exotic Aspect:
The dual-pot feature offers flexibility and efficiency by reducing overall
cooking time and firewood consumption, according to a study by the
Food and Agriculture Organization.

2. Smokeless Chulha:
Design:
These chulhas are designed to minimize smoke and improve air
quality by incorporating a chimney and secondary air inlets.

Exotic Aspect:
The smokeless feature is crucial for health, especially in rural areas
where smoke inhalation is a significant concern.

3. Improved Combustion Chulha:

Design:
This type of chulha focuses on optimizing the combustion process
through features like a dedicated fire-feeding tunnel, a burn chamber
made of bricks and mud donuts, and strategic placement of burners.

Exotic Aspect:
The combination of these elements ensures efficient and cleaner
burning, reducing fuel consumption and emissions.

4. Multi-Functional Chulha:
Design:
 Some designs incorporate additional features, such as a built-in bread
oven or a heating element for water, expanding their utility beyond
cooking.

Exotic Aspect:
The multi-functional aspect makes them more versatile and convenient
for a wider range of cooking needs.

5. Modern Takes on Traditional Chulha:

Design:
Modern chulhas are designed to incorporate elements of traditional
cooking while offering convenience and efficiency.

Exotic Aspect:
These designs may feature electric tandoors or compact clay ovens
with eco-friendly features, allowing for traditional cooking in a
modern setting.
FIXED BASED COMBUSTOR
A fixed-bed combustor is a combustion system where solid fuel is
arranged in a stationary, or "fixed," bed, and air or oxygen is blown
through it to burn the fuel. These systems are commonly used for
burning solid fuels like coal, biomass, or waste. The fuel is typically
sized between 3 and 50 millimeters and is placed on a grate, with
primary air blown under the bed to burn the fixed carbon.
Here's a more detailed breakdown:
Key Features:

Solid Fuel:
Fixed-bed combustors primarily burn solid fuels like
coal, biomass, or other solid materials.

Stationary Bed:
The fuel is held in a stationary bed, usually on a grate, and not moved
during combustion.

Air Supply:
Air or oxygen is blown through the bed to provide the necessary oxygen
for combustion.

Heat Transfer:
Heat is transferred from the combustion process to heat transfer surfaces
(e.g., boiler tubes) to produce steam or hot water.

Applications:
Fixed-bed combustors are used in various applications, including small
domestic stoves, industrial boilers, and power plants.

Advantages:
Simplicity:
They are generally simpler in design compared to other combustion
technologies like fluidized beds.

Cost-Effective:
They can be relatively less expensive to build and operate, especially for
smaller applications.

Wide Fuel Range:

They can handle a variety of fuel types and sizes, though particle size
and moisture content can be a limiting factor.
Disadvantages:
Fuel Size Limitations:
They may not be as efficient with fine or wet fuels compared to other
systems like fluidized beds.

Emission Concerns:
They may produce higher levels of emissions compared to some other
combustion technologies, depending on the fuel and combustion
conditions.

TYPES
Fixed bed combustors primarily utilize two main types: underfeed
stokers and grate firings. Underfeed stokers push fuel into the
combustion zone, while grate firings burn fuel on a grate. These
methods provide a stable bed for combustion and are often used with
solid fuels like biomass.
Elaboration:
Underfeed Stokers:
These systems introduce fuel into the combustion zone from below,
allowing for more controlled combustion and efficient utilization of
the fuel.

Grate Firings:
These systems burn fuel on a grate, with air supplied from below. The
grate supports the fuel bed and allows for the removal of ash.

INCLINED GRATE COMBUSTOR

An inclined grate combustor is a type of combustion system that uses an
inclined grate to burn solid fuels, like biomass, wood, or waste. The fuel
is fed onto the grate and moves downwards due to the incline and the
movement of the grate bars, which allows for controlled combustion and
ash removal.

Here's a more detailed look:

How it works:
Fuel Feeding:
Fuel is fed onto the top of the inclined
grate, often by gravity.

Combustion Zones:
As the fuel moves down, it passes through different combustion zones:
drying, devolatilization (where volatile gases are released), combustion
(where the gases burn), and char burnout (where the remaining carbon is
burned).

Air Supply:
Air is supplied below the grate (primary air) and above the fuel bed
(secondary air) to support combustion.

Ash Removal:
The ash is removed at the bottom of the grate, either into a pit or a
hopper, depending on the grate design.

Grate Movement:
The grate bars move in a reciprocating motion, pushing the fuel down
the grate and allowing for better mixing with air.

Advantages of Inclined Grate Combustors:

Versatility:
They can handle a wide variety of solid fuels, including those with
 varying moisture content, size, and ash content.

Efficiency:
Reciprocating grate systems can achieve high combustion efficiencies,
often between 80 and 90%, according to EPCB Boiler.

Control:
The air supply and grate movement can be adjusted to control the
combustion process, optimizing efficiency and reducing emissions.

Applications:
Boilers: Inclined grate combustors are commonly used in boilers for
generating heat or steam.

Waste Incineration: They can be used for burning waste and biomass.

Power Generation: In some cases, they may be used in power

generation applications, according to EPCB Boiler.

FLUDIZED BED COMBUSTOR

A fluidized bed combustor (FBC) is a
combustion technology where solid fuel
particles are suspended in a hot, bubbling
bed of inert material (like sand or ash) by a
stream of air or gas. This suspension
creates a fluid-like behavior in the bed,
allowing for efficient combustion and heat
transfer.
Key aspects of FBC:
Fluidization:
A stream of air or gas is passed through a bed of solid particles (like
sand or ash) at a velocity high enough to lift the particles and make
them behave like a fluid.

Combustion:
Fuel particles are introduced into the fluidized bed and combust in the
presence of oxygen, which is supplied by the air or gas stream.

Heat Transfer:
The hot, fluidized bed provides efficient heat transfer to heat recovery
surfaces, such as water tubes in a boiler, for steam generation or other
industrial processes.

Types:
FBC can be further categorized into bubbling fluidized bed combustion
(BFBC) and circulating fluidized bed combustion (CFBC), with
differences in how the fuel and bed material are handled.

Advantages of FBC:
High fuel flexibility: FBC systems can burn a wide range of fuels,
including coal, biomass, and low-grade fuels.

Reduced emissions: FBC can help reduce emissions of pollutants like

nitrogen oxides (NOx) and sulfur oxides (SOx).

Efficient heat transfer: The fluidized bed provides excellent heat

transfer, leading to high thermal efficiency.

Easy ash removal: FBC systems can easily remove ash from the
combustion process.

Fast load response: FBC systems can quickly adjust to changes in

energy demand.

Applications of FBC:
Power generation:
FBC is used in power plants to generate electricity, especially for low-
grade fuels.

Industrial processes:
FBC can be used in various industrial processes, such as heating, drying,
and steam generation.