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RENEWABLE ENERGY > FURNACE > Flashcards

FURNACE Flashcards

1
Q

is very much abundant in the
Philippines. In most places there are lots
of biomass material that are being
disposed and dump everyday for the
purpose of eradicating it.

A

BIOMASS

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2
Q

is
a heating device
where fuel is burned
to supply heat to
various processing
operation or generate
steam to produce
power

A

BIOMASS FURNACE

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3
Q

Uses of Biomass Furnace

A

A source of heat for thermal system
A source of heat for boilers to generate steam

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4
Q

As source of heat for
thermal systems:

A

Grain drying
Fruit dehydration
Kiln firing
Fish drying
steaming
Water heating

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5
Q

A source of heat for
boilers to generate
steam fo

A

– Power generation
using steam turbine or
steam engine.
– Source of heat in food
and feed processing
operations.

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6
Q

Classifications of
Biomass Furnaces

A

Fixed Bed
Fluidized Bed
Cyclone Furnace

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7
Q

Primary air is supplied from below the grate
and process of combustion happen on the
grate. The combustible gases produced are burnt,
when secondary air is supplied, usually in a
combustion zone separated from the fuel
bed.
Temperatures in _____ typically
reach 900–1400 ºC.

A

FIXED BED

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8
Q

appropriate for the biomass fuels with
high moisture content, varying particle
sizes and high ash content.

A

Grate Furnaces

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9
Q

is designed for
homogenous distribution of fuel and bed
over the grate areas.

A

Grate system

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10
Q

Grate furnaces are of
various types

A

Fixed grates
Moving grates
Travelling grates
Rotating grates
Vibrating grates

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11
Q

This system are suited for burning both
large and small particulates wood waste
and agricultural residue and can operate
with these fuel at relatively high moisture
content.

The system comprise a combustion
chamber containing a sand bed acting as
the heat transfer medium. Particulate
biomass is introduced into the hot bed
where it undergoes combustion.

A

Fluidized Bed

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12
Q

Two Types of Fluidized Bed

A

Bubbling Fluidized Bed
(BFB)
Circulating Fluidized Bed

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13
Q

the combustor is divided into two zones,
namely a zone containing freemoving
sand bed particles supported by air
flowing upwards, resembling a bubbling
fluid, and a free-board zone above the
fluidized bed.

A

Bubbling Fluidized Bed

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14
Q

The lighter bed particles and fuel particles
are carried by the flow in a circular motion,
form a cyclone, and later return to the
reactor.
The lighter fuel particles burn while aloft
and in circulation whereas the larger or
heavier particles burn while they are
stationary until they become light enough
to join the circulating stream.

A

Circulating Fluidized Bed

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15
Q

These are suitable to burn
particulate waste wood and agricultural
residues typically of regular size and
shape and relatively at low moisture
content. The system comprises a
cylindrical chamber where the combustion
air is introduce tangentially. The cyclonic
regime of the combustion promotes
intimate mixing of suspended particulate
residue allowing efficient combustion.

A

Cyclonic

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16
Q

These are solid
carbonaceous materials derived from
living plant matter

A

Biomass Fuel

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17
Q

Sources of Biomass Fuel

A

Wood, forest residues
Agricultural residues

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18
Q

It is a chemical process to
which one of the reactants is oxygen from
the air and the other is a fuel.

A

Combustion

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19
Q

This is when all
the combustible components are gasified
and all the carbon is burned to carbon
dioxide, all the hydrogen is converted to
water, and sulfur to sulfur dioxide

A

Complete Combustion

20
Q

It is the theoretical amount of
air required to burn a fuel completely to product
with no dissociation.

A

Stoichiometric Air

21
Q

It is the additional amount of
air needed to achieve complete combustion of fuel.
It can be determined by the actual amount of air
used minus the stoichiometric air. In general
excess air of about 65-75% of the theoretical air is
needed for complete combustion. For biomass fuel,
maximum excess is required.

A

Percent Excess Air

22
Q

It is the amount of air
actually used divided by stoichiometric air.

A

Percent theoretical Air

23
Q

It is the air admitted to or with the
fuel. In the case of solid fuel, air pass through
the fuel bed while for gas or liquid, air is admitted
and mixed to the fuel prior to combustion.

A

Primary Air

24
Q

It is the air fed into the furnace
system which does not pass through the fuel
bed. Instead, it is use to further or completely
burn volatile combustible gases. Excessive
amount of secondary air may dilutes air
necessary for combustion and reduces heat
transfer efficiency.

A

Secondary Air

25
Q

Properties of Biomass Fuel

A

Bulk Density
Moisture Content
Proximate Analysis
Ultimate analysis
Calorific Value
Ash properties
Size

26
Q

It is the mass of loosely packed
specified volume of biomass material. This is
important in the cost of transport and storage, and
design of handling and conveying of furnace
systems. It is also a factor to take into account in
the design of combustion chamber.

A

Bulk Density

27
Q

This is the amount of water
contained in the fuel. Free moisture in the fuel
influences performance of the furnace. It must be
taken into account in the design of the combustion
equipment to ensure that combustion chamber
temperature are maintained within limits at which
combustion can take place without causing ash
fusion and fouling

A

Moisture Content

28
Q

It is used to determine the
percentages of volatile matter, fixed carbon, and ash in
the fuel. It gives the indication of the flaming and
glowing combustion. The ash provides a measure of the
incombustible mineral matter in the fuel

A

Proximate analysis

29
Q

It determines chemical
composition of fuels in terms of carbon, hydrogen,
oxygen, nitrogen, and sulphur as mass percentages of
dry and ash free biomass material. This is essential in
estimating air requirements, flue losses, and
emission of pollutants.

A

Ultimate analysis

30
Q

It is important since it determines the
quantity of fuel which must be burnt to meet a given duty. This can be determined in the laboratory using bomb
calorimeter or can be computed using an equation.

A

Calorific Value

31
Q

This plays a very important in
role in the fouling, slagging, clinker formation
and erosion properties. Knowledge of the fusion
temperature of biomass ashes can help in the
choice of the optimum temperature to suitably
operate a furnace.

A

Ash Properties

32
Q

Some biomass fuel requires size
reduction and/or other properties which is
dependent upon the type and scale of the
combustion equipment. Feeding biomass fuel
and controlling its operation using automatic
feeders, conveyors, spreaders will require fuel
that is uniformly sized.

A

Size

33
Q

Component Parts of a
Furnace System

A

Fuel storage
Feeding mechanism
Combustion system

34
Q

•Combustion System parts

A

Combustion chamber
Fuel Stoker
Ash removal
Heat Exchanger
Fuel Gas Outlet

35
Q

Important Factors to Consider
in Biomass Furnace Design

A

Physical Properties of Fuel
Fuel-Bed Temperature
Volume Change-Temperature-Time Relationship
Air Requirement for Combustion

36
Q

Sensible Heat Requirement

A

Qh = m cp
(T2 – T1
)
where:
Qh
- energy required to heat the materials,
kCal/hr
m - mass flow rate of the material, kg/hr
cp
- specific heat of the material, kCal/kg-C
T2
- final temperature of the material, C
T1
- initial temperature of the material, C

37
Q

Energy Required for Drying

A

Qd = Wi [1 – (1-MCi)/(1-MCf)] x Hfg
where:
Qd
- energy required for drying, kCal hr
Wi - weight initial of product, kg
MCi - initial moisture of product, % wb
MCf - final moisture of product, %wb Hfg
- heat of vaporization of moisture from
the product, kCal/h

38
Q

Fuel Consumption Rate

A

FCR = 100 Qs [ HVF x ξ]
where:
FCR - amount of fuel to be consumed,
kg/hr
Qs - total heat required for the system,
kCal/hr
HVF - heating value of fuel, kCal/kg
ξ - overall thermal efficiency, %

39
Q

Airflow Requirement

A

AFR = FCR x SAR
where:
AFR - airflow rate required for combustion,
kg air/hr
FCR - fuel consumption rate, kg fuel hr
SAR - stoichiometric air requirement, kg
air / kg fuel

40
Q

System Thermal
Efficiency

A

ξ= 100 Qs / [FCR x HVF)
where:
ξ- overall thermal system efficiency%
Qs - heat supplied to the system, kCal/hr
FCR - fuel consumption rate, kg/hr
HVF - fuel heating value, kCal/kg

41
Q

SAMPLE PROBLEM:
A furnace is required to supply heat to a water boiler for a
kiln dryer. The boiler tank contains 2 cubic meters of water
and need to be heated from 27 C to 100 C within 1 hour. The boiler is required to maintain the temperature of water
at 100 C and allows water to evaporate at 100 kg per hour. What is the power input of furnace in raising the
temperature of the water and in maintaining its operation?
Assume a boiler efficiency of 70% and furnace efficiency of
40%, and heat of vaporization of water of 540 kCal/kg.

A

Given:
V – 2 m3
T1-27C
T2-100C
M – 100 kg/hr;
b – 70%
f – 40%

42
Q

It is the amount of heat
energy that the furnace can deliver.

A

Heat output

43
Q

It is the amount
of fuel that can be burned per unit time

A

Fuel Consumption Rate

44
Q

It is the of heat
energy that can be utilized from energy
available from the fuel.

A

Furnace efficiency

45
Q

It is the amount of
energy that is still available from the ash of
from the fuel that is burned.

A

Burning Efficiency

RENEWABLE ENERGY (2 decks)

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