A Project Report on

FLUIDIZED BED COMBUSTIONS FOR ENERGY CONVERSIONS

In

Advanced Energy Systems

Under the Guidance of

Dr. Ramazan Asmatulu

Submitted by

Shravani Kasaragadda (W268D427)

Goutham Chinni (K474R658)

Gopi Krishna Mandadi (K353X443)

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CONTENTS

Abstract

List of figures

1. Introduction General Background

Motivation

Objectives

2. Literature Review

3. Experimental Materials

Methods

4. Results & Discussion

5. Conclusions

6. Future work

7. References

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Abstract

A fluidized bed is a unique reactor where the fuel that is smoldered is kept up in movement,

coursing in a smooth movement keeping in mind the end goal to burn completely. This

procedure builds the productivity of the reactor, and, all the more significantly, lessens the

aggregate greenhouse gas and particulate outflows. Burning coal with biomass in a fluidized bed

diminishes destructive discharges from the ignition of these powers independently while in the

meantime lessens the nursery gas outflows from the coal. This innovation has bit by bit enhanced

and is currently sent on a business premise. On the other hand, proceeded with R&D in this field

is expected to further enhance fuel burning effectiveness, keeping up high fuel adaptability at

stringent greenhouse gas limits. Co-operation between scientists, modern agents and

administrative projects quickens the information base and innovation organization. With the

developing vitality requests in the force part, Fluidized bed combustion (FBC) innovation is

ceaselessly picking up significance because of its capacity to smolder distinctive second rate

coals and the nonattendance of NOx creation. Research needs on the point of fluidization are

essentially identified with blending of fuel, solids furthermore, gas, including entrance and

blending of auxiliary air. The bigger the cross area of the heater, the more basic is the fuel

blending, i.e. this is basic for expansive power boilers. For little and medium scale FBC boilers

smoldering waste and waste inferred powers, there is likewise a need to comprehend fuel and gas

blending keeping in mind the end goal to be ready to bring down the overabundance air

proportion and, along these lines, to build the effectiveness.

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1. INTRODUCTION

General Background

Fluidized bed combustion (FBC) is a technology used for generation of heat, power and a

combination of these. It is a unique reactor where the fuel is burned and maintained in motion,

circulating in a fluid motion in order to burn thoroughly. There has been a consistent

advancement and refinement of the innovation since it came to business status in the mid 80's.

As for the improvement of the innovation, two elements can be specified which to a sure degree

make the FBC advancement contrast from that of other strong fuel burning advances. In the first

place, the fuel adaptability, which is one of the fundamental points of interest of the innovation,

has put concentrate on distinctive fills after some time subsequent to the presentation of the FBC

innovation. It has been reported that it is one of the most efficient and suitable process for

converting the agricultural and food residues into energy. The bed furnaces were introduced

around 25-30 years ago, and the refractory materials such as sand or limestone are suspended by

air currents and they are the medium for the heat transfer to the biomass fuel. Fuel flexibility is

one of the main advantages of the technology. Development of fluidized bed combustion

technology development is different in different regions of the world, depending on the fluid

availability. Depending on the type of fuels, the technology demands differently.

There are 2 main applications of the FBC technology is that, 1. Combined heat and power (CHP)

that burns renewable and waste fuels and 2. Large power boilers mainly coal yield different

problems and challenges. There are 2 types of fluidized bed boilers they are, 1. Bubbling

fluidized bed and 2. Circulating fluidized beds which operate under the atmospheric conditions.

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Objectives

Fluidization

Fluidization is a procedure like liquefaction whereby a granular material is changed over from a

static strong like state to a dynamic liquid like state. This procedure happens when a liquid (fluid

or gas) is left behind through the granular material. Whenever a gas stream is presented through

the base of a bed of strong particles, it will move upwards through the bed by means of the

unfilled spaces between the particles. At low gas speeds, streamlined delay every molecule is

likewise low, and along these lines the bed stays in a settled state. Expanding the speed, the

streamlined drag powers will start to check the gravitational powers, making the bed grow in

volume as the particles move far from one another. Further expanding the speed, it will achieve a

basic worth at which the upward drag powers will precisely measure up to the descending

gravitational powers, bringing about the particles to end up suspended inside of the liquid. At

this basic esteem, the bed is said to be fluidized and will display fluidic conduct. By further

expanding gas speed, the mass thickness of the bed will keep on diminishing, and its fluidization

turns out to be more vicious, until the particles no more shape a quaint little inn "passed on"

upwards by the gas stream. Whenever fluidized, a bed of strong particles will carry on as a

liquid, similar to a fluid or gas. Like water in a basin: the bed will adjust to the volume of the

chamber, its surface remaining opposite to gravity; objects with a lower thickness than the bed

thickness will skim on its surface, swaying here and there if pushed downwards, while objects

with a higher thickness sink to the base of the bed. The fluidic conduct permits the particles to be

transported like a liquid, diverted through channels, not requiring mechanical transport. A

rearranged each day-life sample of a gas-strong fluidized bed would be a hot-air popcorn popper.

The popcorn portions, all being genuinely uniform fit as a fiddle, are suspended in the hot air

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ascending from the base chamber. As a result of the serious blending of the particles, similar to

that of a bubbling fluid, this takes into account a uniform temperature of the bits all through the

chamber, minimizing the measure of blazed popcorn. Subsequent to popping, the now bigger

popcorn particles experience expanded streamlined drag which pushes them out of the chamber

and into a dish.

Figure 1:demonstrates the Spain's Sogama waste to vitality office procedure chart.

The Sogama plant will handle roughly 650,000 tons of MSW into 400,000 tons of Refuse

Derived Fuel (RDF) every year. The plant comprises of four noteworthy parts. Metropolitan

Solid Waste (MSW) is conveyed by rail from exchange stations, the materials recuperation

office, the kettle island, the turbine island, and the cogeneration plant. MSW is bolstered into

encumber, which isolates small and large particles. The waste is dried by hot gasses from the

cogeneration plant and profitable material recouped for reusing. The staying material is

destroyed and passed on to the boilers. Reused material will incorporate glass, paper, iron,

aluminum, plastics, and cardboard. A heater consolidating to 75 MW and Circulating Fluidized

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Bed (CFB) boilers, a dry vent gas cleaning framework and a pack house channel. This segment

represents 33% of the aggregate expense of the plant.

Efficiency of the Combustion Process

Fluidized-bed boilers are the most well-known kind of heater suggested for biomass fuel, which

is blazed inside of a hot bed of idle particles, commonly sand. The fuel-molecule blend is

suspended by an upward stream of burning air inside of the bed. As speeds build the gas/strong

blend displays liquid like properties. As per the EPA's "Consolidated Heat and Power

Partnership Biomass CHP Catalog," the scouring activity of the bed material on the fuel likewise

upgrades the stripping so as to burn procedure "away the CO2 and solids buildup (scorch) that

ordinarily conforms to the fuel particles. Permitting oxygen to achieve the ignitable material all

the more promptly and build the rate and proficiency of the burning procedure."

This procedure additionally builds warmth exchange and takes into consideration lower working

temperatures: bed temperatures range around 1,400° F to 1,600° F, far not exactly the 2,200° F

for a spreader stoker kettle. Lower heater temperatures additionally create less nitrogen oxide, an

ecological and administrative advantage when smoldering high nitrogen-content wood and

biomass powers. Sulfur dioxide emanations from wood waste and biomass are for the most part

unimportant; be that as it may, if sulfur is a contaminant it can be killed by adding limestone to

the fluid bed.

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2. Literature review

https://www.academia.edu/3144562/

Fine_Particle_Emissions_During_Fluidized_Bed_Combustion_of_Coal_and_Waste-

Derived_Fuels

Fluidized Bed Combustion

Beside suspension terminating of wood, the most effective technique for straightforwardly

smoldering biomass is in a fluidized bed combustor (FBC). This is additionally the most flexible

since the framework can adapt to an extensive variety of powers and a scope of dampness

substance. The premise for a FBC framework is a bed of a latent mineral, for example, sand or

limestone through which air is blown from beneath. The air is pumped through the bed in

adequate volume and at a sufficiently high weight to entrain the little particles of the bed material

so that they act much like a liquid.

The burning assembly of a fluidized bed plant is molded so that over a sure stature the air speed

drops beneath that important to entrain the particles. This holds the greater part of the entrained

bed material towards the base of the chamber. When the bed gets to be hot, ignitable material

brought into it will blaze, creating warmth as in a more routine heater. The extent of flammable

material, for example, biomass inside of the bed is ordinarily just around 5%. There are diverse

outlines of FBC framework which include varieties around this standard. The most regular for

biomass burning is the flowing fluidized bed which consolidates a tornado channel to discrete

strong material from the hot pipe gasses which leave the fumes of the heater. The solids from the

channel are re-coursed into the bed, subsequently the name. The fluidized bed has two

unmistakable focal points for biomass ignition: First, it is the capacity to smolder an assortment

of diverse powers without influencing execution. Second is the capacity to bring compound

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reactants into the fluidized bed to evacuate conceivable poisons. In FBC plants smoldering coal,

for instance, limestone can be added to catch sulfur and keep its discharge to the climate as sulfur

dioxide. Biomass has a tendency to contain less sulfur than coal so this system may not be

essential in a biomass plant.

A fluidized bed kettle can consume wood with to 55% dampness. One specific application is in

plants intended to smolder chicken litter, the decline from the serious cultivating of poultry.

Force stations have been fabricated that are dedicated particularly to this fuel source and these

plants use FBCs. Of the four unique sorts of ignition advances examined over, the FBC

innovation is most appropriate for a scope of little and medium scale operation for joined warmth

and force. With mechanical progressions the FBC boilers give effectiveness of as high as 80-

82% and can be utilized for a wide assortment of powers.

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Comparasion of different types of conversion technologies

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Mechanism Of Fluidised Bed mechanism

At the point when an uniformly dispersed air or gas is gone upward through a finely isolated bed

of strong particles, for example, sand bolstered on a fine work, the particles stay undisturbed at

low speeds. As the air speed is bit by bit expanded, a stage is come to when the person particles

are suspended noticeable all around stream and the bed is called "fluidized". With further

increment in air speed, there is air pocket development, overwhelming turbulence, fast blending

and development of thick characterized bed surface. The bed of strong particles shows the

properties of a bubbling fluid and accept the presence of a liquid – "percolating fluidized bed".

At higher speeds, air pockets vanish, and particles are extinguished of the bed. Along these lines,

a few measures of particles must be re-circled to keep up a steady framework and is called as

"circulating fluidized bed". This guideline of fluidization is shown in Figure. Fluidization

depends to a great extent on the molecule size and the air speed. The mean solids speed

increments at a slower rate than does the gas speed. The distinction between the mean strong

speed and mean gas speed is called as slip speed. Most extreme slip speed between the solids and

the gas is attractive for good warmth exchange and cozy contact. In the event that sand particles

in fluidized state are warmed to the ignition temperatures of fuel (rice husk, coal or bagasse),

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what's more, fuel is infused persistently into the bed, the fuel will blaze quickly and the bed

accomplishes a uniform temperature.

The fluidized bed burning (FBC) happens at around 840°C to 950°C. Since this temperature is

much beneath the cinder combination temperature, liquefying of fiery debris and related issues

are maintained a strategic distance from. The lower ignition temperature is accomplished as a

result of high coefficient of warmth exchange because of fast blending in the fluidized quaint

little inn extraction of heat from the bed through in-bed warmth exchange tubes and dividers of

the bed. The gas speed is kept up between least fluidization speed and molecule entrainment

speed. This guarantees a steady operation of the overnight boardinghouse molecule entrainment

in the gas stream.

Fig 2: principle of fluidization

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Any ignition procedure requires three "T"s - that is Time, Temperature and Turbulence. In FBC,

turbulence is advanced by fluidization. Enhanced blending produces equitably circulated heat at

lower temperature. Living arrangement time is ordinarily higher than traditional mesh

terminating. In this manner a FBC framework discharges warm all the more productively at

lower temperatures. Since limestone can likewise be utilized as molecule bed (on the off chance

that the fuel with sulfur substance is utilized), control of SOx and NOx emanations in the

burning chamber is accomplished with no extra control hardware. This is one of the real

favorable circumstances over conventional boilers.

Types of FBC Boiler’s

There are three basic types of fluidized bed combustion boilers:

1. Atmospheric Fluidized Bed Combustion System (AFBC)

2. Atmospheric circulating (fast) Fluidized Bed Combustion system (CFBC)

3. Pressurized Fluidized Bed Combustion System (PFBC).

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3.MATERIALS AND METHODS:

https://www.academia.edu/3144562/

Fine_Particle_Emissions_During_Fluidized_Bed_Combustion_of_Coal_and_Waste-

Derived_Fuels.

Fluidized bed combustion (FBC) is today an entrenched innovation for era of warmth, force and

a mix of these. Yet, there has been a steady advancement and refinement of the innovation since

it came to business status in the mid 80's. As for the improvement of the innovation, two

variables can be specified which to a sure degree make the FBC advancement vary from that of

other strong fuel ignition advances. To start with, the fuel adaptability, which is one of the

primary focal points of the innovation, has put concentrate on distinctive powers after some time

subsequent to the presentation of the FBC innovation. The center of the advancement has

additionally been diverse in distinctive locales of the world, contingent upon accessibility. In this

manner, the different sorts of fills yield distinctive requests on the innovation (significance of

blending, material issues, warmth exchange conveyance and so on.). Besides, the two principle

utilizations of the FBC innovation, littler warmth just or joined warmth and force (CHP) boilers

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copying renewable and waste powers and expansive force boilers for the most part copying coal

yield distinctive issues and difficulties, as talked about underneath.

(http://www.unep.org/climatechange/mitigation/Portals/93/documents/EnergyEfficiency/

FBC_30_sep_2007.pdf)

Fixing, bubbling and fast fluidized beds

As the speed of a gas coursing through a bed of particles builds, a quality is ranges when the bed

fluidizes and air pockets structure as in a bubbling fluid. At higher speeds the air pockets vanish;

and the solids are quickly smothered of the quaint little inn be reused to keep up a steady

framework. Burning procedure requires the three "T"s that is Time, Temperature and

Turbulence. In FBC, turbulence is advanced by fluidization. Enhanced blending produces

uniformly circulated heat at lower temperature. Home time is commonly more noteworthy than

customary mesh terminating. In this manner a FBC framework discharges warm all the more

proficiently at lower temperatures.

Figure 3: Relations between Gas Velocity and Solid Velocity

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Since limestone is utilized as molecule bed, control of sulfur dioxide and nitrogen oxide

discharges in the ignition chamber is accomplished with no extra control gear. This is one of the

real points of interest over customary boilers.

AFBC / Bubbling Bed

In AFBC, coal is pounded to a size of 1 – 10 mm relying upon the rank of coal, kind of fuel

encourage and bolstered into the ignition chamber. The air, which goes about as both the

fluidization air and burning air, is conveyed at a weight and moves through the bed in the wake

of being preheated by the fumes vent gasses. The speed of fluidizing air is in the scope of 1.2 to

3.7 m/sec. The rate at which air is blown through the bed decides the measure of fuel that can be

responded.

All AFBC/foaming bed boilers use in-bed evaporator tubes in the bed of limestone, sand and fuel

for extricating the warmth from the bed to keep up the bed temperature. The bed profundity is

typically 0.9 m to 1.5 m profound and the weight drop midpoints around 1 inch of water for

every inch of bed profundity. Next to no material leaves the foaming bed – just around 2 to 4 kg

of solids are reused per ton of fuel blazed. Regular fluidized bed combustors of this sort are

appeared in underneath figures.

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Figure 4: Bubbling Bed Boiler-1

Features of bubbling bed boiler

Fluidized bed evaporator can work at close barometrical or raised weight and have these key

components:

• Distribution plate through which air is blown for fluidizing.

• Immersed steam-raising or water warming tubes which concentrate warm specifically from the

bed

Figure 5: Bubbling Bed Boiler-2

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The burning gasses disregard the super warmer areas of the kettle, stream past the economizer,

the dust gatherers and the air preheaters before being depleted to air. The principle uncommon

element of climatic fluidized bed burning is the requirement forced by the moderately limit

temperature range inside which the bed must be worked. With coal, there is danger of clinker

arrangement in the bed if the temperature surpasses 950 0C and loss of ignition productivity if the

temperature falls underneath 8000C. For productive sulfur maintenance, the temperature ought to

be in the scope of 800 0C to 850 0C.

a) Fuel Feeding System

For encouraging fuel and adsorbents like limestone or dolomite, normally two strategies are

taken after: under bed pneumatic sustaining and over-bed bolstering.

Under Bed Pneumatic Feeding

On the off chance that the fuel is coal, it is pounded to 1–6 mm size and pneumatically

transported from food container to the combustor through a food channel puncturing the

merchant. In view of the limit of the evaporator, the quantity of food focuses is expanded, as it is

important to appropriate the fuel into the bed consistently.

Over-Bed Feeding

The smashed coal, 6–10 mm size is passed on from coal dugout to a spreader by a screw

transport. The spreader appropriates the coal over the surface of the bed consistently. This sort of

fuel nourishing framework acknowledges over size fuel additionally and dispenses with transport

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lines, at the point when contrasted with under-bed encouraging framework. Presently a days for

rise husk and other farming buildups over bed bolstering framework is very conspicuous and

efficient. Some of the boilers are designed to the point that they have both sorts of bolstering

frameworks.

b) Air Distributor

The motivation behind the wholesaler is to present the fluidizing air uniformly through the bed

cross segment in this manner keeping the strong particles in consistent movement, and keeping

the development of de-fluidization zones inside of the bed. The wholesaler, which frames the

heater floor ordinarily built from metal plate with various punctures in a positive geometric

design. The holes may be situated in straightforward spouts or spouts with air pocket tops, which

serve to keep strong particles from streaming once more into the space underneath the merchant.

The distributor plate is shielded from high temperature of the heater by:

Hard-headed Lining

A Static Layer of the Bed Material or

Water cooled tubes

c) Bed and In-Bed Heat Transfer Surface:

Bed

The bed material can be sand, fiery remains, smashed obstinate or limestone, with a normal size

of around 1 mm. Contingent upon the bed stature these are of two sorts: shallow quaint little inn

profound bed. At the same fluidizing speed, the two closures fluidize in an unexpected way, in

this way influencing the warmth exchange to a drenched warmth exchange surfaces. A shallow

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bed offers a lower bed resistance and thus a lower weight drop and lower fan power utilization.

In the instance of profound bed, the weight drop is more and this expands the viable gas speed

furthermore the fan power.

In-Bed Heat Transfer Surface

In a fluidized in-bed warmth exchange process, it is important to exchange warmth between the

bed material and a submerged surface, which could be that of a tube group, or a loop. The

warmth exchanger introduction can be flat, vertical or slanted. From a weight sloping edge of

perspective, an even package in a shallow bed is more appealing than a vertical pack in a

profound bed. Additionally, the warmth move in the bed relies on upon number of parameters

like (i) bed weight (ii) bed temperature (iii) shallow gas speed (iv) Molecule size (v) Heat

exchanger configuration and (vi) gas wholesaler plate outline.

d) Ash Handling System

i) Bottom Ash Removal

In the FBC boilers, the base slag constitutes around 30 – 40 % of the aggregate powder, the rest

being the fly slag. The bed fiery remains is uprooted by constant over stream to look after bed

stature furthermore by discontinuous stream from the base to uproot over size particles, maintain

a strategic distance from collection and subsequent DE fluidization. While terminating high fiery

remains coal, for example, washery rejects, the bed fiery remains flood channel amount is

significant so uncommon consideration has to be taken.

ii) Fly Ash Removal

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The measure of fly fiery remains to be taken care of in FBC evaporator is moderately high,

contrasted with ordinary boilers. This is because of elutriation of particles at high speeds. Fly

powder diverted by the vent gas is uprooted in number of stages; firstly in convection area, at

that point from the base of air pre-warmer/economizer lastly a noteworthy bit is uprooted in dust

authorities. The sorts of dust gatherers utilized are violent wind, pack channels, electrostatic

precipitators (ESP's) or some mix of these. To build the ignition proficiency, reusing of fly

powder is honed in a few

4. RESULTS AND DISCUSSIONS

The examinations of the samples by using scanning electron microscope for the bed materials

have shown that a thickness for the coating ranges from 10-50 µm was conformed to all bed

particles. A case of this coating can plainly be seen from the SEM backscatter micrographs

appeared as shown in below figure. To one side, a micrograph of a bed test from the 18 MWth

CFB boiler is appeared; to one side, a comparative picture is appeared for a bed test gathered

from the 5 kW bench scale reactor amid the controlled bed agglomeration test of wood. The

coatings can be recognized on the bed particles as lighter surroundings encompassing the darker

SiO2 centers. The dark foundations found in the micrographs are the epoxy in which the bed

tests were mounted. A light region demonstrates a higher concentration of the component being

referred to than a dark area.

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Figure-6 : Images of a polished wood bed samples on Back scattered electron

Figure below is a case of the SEM/EDS component mapping examination for the same bench

scale bed test as shown in above figure.

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Figure-7

The element corresponds for all fuels have a different ratios for all the coatings from the

elements like Silicon (Si), Potassium (K), Sodium (Na), Iron (Fe), Calcium (Ca) and Aluminum

(Al) and it varies on all the elements by differentiating silicates.

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Figure- 8: Mole Percentage except O2 for all the elements in bulk bed varying ash components.

The elemental analysis for the samples on bed bulk are shown in the below table. As from the

table, we can expect that the silicon dominates the composition of the sample as the ash forming

elements in the bed was retained by the major fraction of the fuel; the part was completely

depleted by some elements in the fuel except S and Cl. The concentration of the elements in the

full scale boilers is very low, and this can be stated in the waste sludge and bark incineration

during the ash formation. In the bench scale reactor, by using the sampling and element analysis

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we can state that the transportation and the vaporization of elements like Sulfur, Sodium,

Potassium and chlorine have transported from the bed.

This vaporization in the bench scale reactor has been increased with the increase in temperature

of the bed during the stage of combustion. And during the stage of heating phase, no vapors are

found in the external phase although the temperature has been increased to 960C. From this, we

can state that because of the characteristics of the coating, during different phases of heating also

it seem to be reliable and preserved.

From the above figure, each bar states the results of spot analysis taken from the bed particle

which has been coated. From the figure, we can state that in all cases, Silicon is the only

dominating element and rather than this Si, other elements are K and Ca. But in peat coatings,

Iron is a major element. For RDF and grass, the Aluminum and Sodium are the major elements.

By the analysis of the coatings from the results of fuel ash elemental samples data, we can state

that the elements distribution varies significantly and also based upon this distribution

comparison the ash analysis of the fuel doesn’t provide a good reliable as the tendency of the

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element bed agglomeration may differ from the actual coating. The Results of SEM/EDS

analyses states that bed particles which are covered using the layers are homogeneous and the

coatings of all the elements vary because of using different fuels and samples for bed.

On the other hand, the peripheral layer of the covering may be made out of a heterogeneous

mixture of diverse particles. With time, on the other hand, homogenization appears to occur. This

is by all accounts in concurrence with the late SEM investigations of agglomerates from

smoldering backwoods deposit in a 35 MWth CFB boiler. Samples gathered at the point when

terminating wood, bark, wood deposits, cane trash, and wheat straw demonstrate that the general

compositional appropriations of the significant portion of the bed molecule coatings are

principally restricted (>90% of the material) to the ternary framework K2O-CaO-SiO2.

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Figure shows that the K2O-CaO-SiO2 ternary chart with a few solidus (starting dissolving)

temperatures and the structures of the bed material coatings from utilizing distinctive powers.

The concoction arrangements of these specimens are predominantly limited to the SiO2 rich

corner in Figure, and silicates with these arrangements have a first dissolving temperature of 720

°C, while a little expansion of calcium will move this worth to approximately 1080 °C. Past

results have demonstrated that the concoction qualities, and along these lines the liquefying

practices of the coatings, are imperative for the bed agglomeration process. On the off chance

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that the covering has a sufficiently high part of liquid stage, it will bring about bed

agglomeration, and, in the most serious cases, defluidization.

For silicate liquefies, the consistency of the melt must be mulled over to decide the division

required for "stickiness". It was thusly of enthusiasm to decide the liquefying practices of the

diverse bed coatings, and look at the dissolving temperatures with the relating particular

agglomeration temperatures. Attributable to an absence of thermodynamic information for a few

middle of the road stages in the framework K2O-CaO-SiO2, thermodynamic multicomponent,

and multiphase harmony estimations couldn't be utilized to precisely decide the liquefying

practices. Rather, the assessment was performed by removing dissolving conduct information

from the stage outline K2O-CaO-SiO2.

Only coatings that had natural creations (>90%) inside of the synthesis triangles in Figure 8

were incorporated into the correlation. The subsequent parts of melt (strong lines) versus

temperature are appeared in Figure 9 together with the decided beginning agglomeration

temperature (broken lines), dictated by the controlled fluidized bed agglomeration system.

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Figure-11 : chemical sub processes for the mechanism of bed agglomeration.

The behavior at melting point is sensitive for the elements of K and Ca for the samples. Coatings

with K (high amount) and Ca (low amount) contain large content of melting temperature. And

Coatings with K (low amount) and Ca (high amount) doesn’t contains large content of melting

temperature. The agglomeration temperature follows the melting behavior when it contains high

content of melt in the coating and hence we can conclude that for the agglomeration the reason is

the melt formation.

From the chemical sub processes for the mechanism of bed agglomeration, we can state that:

1. The deposition of the ash on the material of the bed is dominated by combining smaller

particles or elements on the bed particles surfaces. By using the process of condensation

on the bed particles by using elements like Potassium chloride and Potassium Hydroxide.

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2. As the bed particles are followed by continuous deposition then the inner layer becomes

strengthened by using sintering. The main coating characteristics like thickness are

maintained continuously for 7 to 29 hours running time.

3. The melting behavior of the layers by using the homogeneous layers is controlled by

using Adhesive forces. These forces are used to control the final temperature in the

agglomeration process.

And we can conclude that the elements which are found in the fuel are coated and this

differentiates between coatings and the bed materials. The bed particles are coated by using ash

layer which is homogeneous and the main reason for the melting is the formation of sticky layer

on the coating material of the bed causes defluidization and this may result in bed agglomeration.

The characteristics of the elements depend on the coating type which results in the melting

behavior and from results we can say that the melts (silicon) are the main reason for the process

of agglomeration.

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5. CONCLUSIONS

In right on time organize the fluidized bed burning is observed to be the most unmistakable and

utilized for transformation of wood buildups and rural to vitality furthermore for cofiring. For the

biomass ignition which was presented around 30 years back the fluidized bed heaters are utilized

. Unmanageable materials, for example, lime stone and sand are suspended via air streams as

serve as medium for warmth for biomass fuel. High air speeds fluidize the warmth exchange

medium and biomass fuel. On the off chance that the particles stay suspended with the heater the

heater is called foaming fluidized bed. However in the event that the air speed is sufficiently high

to complete materials of the heater to be recycled, the heater is known as a circling fluidized bed.

Molecule isolation in foaming fluidized beds is basically brought about by the distinctions in

molecule densities of diverse fills. The burning temperature must be kept low around 9000C to

avert cinder sintering which could bring about DE fluidization.

For fluidized bed ignition, the fuel bed incorporates a sulfur-retaining sorbent, for example,

limestone or dolomite, which can lessen SO2 discharges by > 95%.As an outcome, fluidized bed

burning frameworks can meet most ecological models for sulfur dioxide and nitrogen dioxide,

without the requirement for post burning contamination controls.

Stuffed ignition frameworks are mesh let go heaters deprive stokers (coal is encouraged from

underneath the smoldering fuel bed). Diverse sorts of mesh heaters (up to 20 MW warm) are

accessible: settled, moving, voyaging, turning and vibrating. They are by and large not useful for

direct cofiring contrasted with fluidized bed boilers in view of the fuel property contrasts.

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Last, pummeled fuel burning frameworks utilize pneumatically nourished fills. The biomass fuel

part may incorporate saw dust, fine shavings of woody plants, and straws. In this burning mode,

fuel amount should be kept up; the greatest fuel molecule size ought to be 10-20mm.

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6. FUTURE WORK / DEVELOPMENTS

(http://www.processeng.biz/iea-fbc.org/upload/Developments_2005_2010.pdf)\

Amid the first half decade after the patent on fluidized bed for fuel change 1922 just a couple

gasifiers were constructed with fluidized bed. Be that as it may, fluidized bed additionally

discovered a few applications in the concoction and petroleum industry. An overall enthusiasm

for fluidized bed as a fuel converter rose in the 1970s when it was understood that fluidized bed

change offered a few ecological points of interest. This began a striking advancement in different

nations. Among different exercises, in 1980 a co-operation on the advancement of fluidized bed

burning (FBC) was started inside of the Universal Energy Agency (IEA) with support from

around ten OECD nations. Later, this action was expanded to incorporate additionally

gasification and the name was changed to fluidized bed change (FBC). Likewise, a few non-

OECD nations were welcome to take an interest. This action still goes on, in spite of the fact that

its character has changed marginally, as the information on FBC is expanding. Amid the late

years center has been on chosen issue zones, as can be seen from the productions found on the

site www.processeng.biz/iea-fbc.org/

At first, yearly reports were issued by the IEA-FBC co-operation, yet after a few years this was

found to be of restricted worth, and the yearly reports were supplanted by the site where

generally significant data about the association of the co-operation and reported results can

without much of a stretch be found. Amid the meeting in Göteborg (May 2010) a few individuals

felt that the time had come to make an outline of the status on FBC in the part nations, and the

delegates from the 16 part nations consented to make a short study on the circumstance in every

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nation. The reason for existing is to demonstrate the conditions for FBC, which change from

nation to nation, and the late advancement in every nation, say amid the most recent five years.

Calcium Looping Cycle

(http://www.processeng.biz/iea-fbc.org/upload/Developments_2005_2010.pdf)

Improvement/testing of a flowing fluidized bed CO2 circling cycle pilot plant (for

catch/sequestration of CO2 with a reusable calcium sorbent) has been progressing. Research and

development is additionally being done on sorbent adjustment for CO2 circling cycles. Pilot-

scale work in Ottawa has now effectively exhibited CO2 circling utilizing the dual FBC test

office with more than 80% expulsion of CO2 from the carbonator and recovery accomplished

with oxy-terminating of biomass. Proceeding with pilot-scale chip away at CO2 circling

exhibition utilizing the double fluidized bed ignition test office is centered around enhancing

execution of characteristic sorbents by: molecule steady loss examinations and displaying; result

assessment under gasification union gas conditions; sorbent reactivation; heat treatment;

incomplete sulphation; and palletization. The studies are relied upon to prompt further scale-up

utilizing CanmetENERGY's 0.8 MWth flowing fluidized bed ignition facility with a scope of

Canadian feed stocks. High-pressure Combustion using FBC Technology

CanmetENERGY and its partner ThermoEnergy Corporation of the U.S.A. have developed a

multi-fuel combustion process termed HiPrOx (High Pressure Oxy-fuel). This novel high

efficiency power generating process captures CO2, along with other emissions, ready for

sequestration. The process uses high-pressure fluidized bed technology for the combustion of

fuel. Research is ongoing.

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7. REFERENCES:

1) Technical Study Report on B IOMASS F IRED Fluidized Bed Combustion Boiler Technology

For Cogeneration.

2) Bed Agglomeration Characteristics during Fluidized Bed Combustion of Biomass Fuels by

Marcus O¨ hman and Anders Nordin Energy Technology Centre, Department of Chemistry,

Inorganic Chemistry, Umeå University, P.O. Box 726, S-941 28 Piteå, Sweden.

3) Baxter, L. L.; Miles, T. R.; Miles, T. R.; Jenkins, B. M.; Milne, T. A.; Dayton, D. C.; Bryers, R.

W.; Oden, L. L. Sandia report SAND96- 8587*UC-1301, 1996.

4) Latva-Somppi, J.; Kurkela, J.; Tapper, U.; Kauppinen, E. I.; Jokiniemi, J. K.; Johanson, B.

Proceedings of the International Conference on Ash Behavior Control in Energy Conversion

Systems, Pacifico Yokohama, Japan, 1998, pp 119-126.

5) Chemical-Looping Combustion with NiO and Fe2O3 in a Thermobalance and Circulating

Fluidized Bed Reactor with Double Loops Sung Real Son and Sang Done Kim.

6) NO and N20 Formation for Coal Combustion in a Fluidized Bed: Effect of Carbon Conversion

and Bed Temperature Claes J. Tullin,? Shakti Goel, Atsushi Morihara,z Adel F. Sarofim.

7) www.iea.org/techinitiatives/fossilfuels/fluidizedbedconversion/

8) A Comparison of Fluid-Bed Technologies for Renewable Energy Applications Authors: J.P.

DeFusco P.A. McKenzie W.R. Stirgwolt Babcock & Wilcox Power Generation Group, Inc.

Barberton, Ohio, U.S.A. Presented to: Renewable Energy World Conference Date: February 23-

25, 2010 Location: Austin, Texas, U.S.A.

9) Fluidized-Bed Combustors for Biomass Boilers September 2012 by Mark Crawford,

ASME.org.

36

10) Fluidized Bed Combustion for Clean Energy Filip Johnsson Refereed Proceedings The 12th

International Conference on Fluidization - New Horizons in Fluidization Engineering

Engineering Conferences International Year 2007.

11) Use of Fluidized Bed Technology in Solid Waste Management Doyce Tesoro-Martinez1 ,

Tomas U. Ganiron Jr2 and Harold S. Taylor3.

12) DEVELOPMENTS IN FLUIDIZED BED CONVERSION DURING 2005‐2010 A

summary from the member countries of the IEA‐FBC Implementing Agreement.

13) A Survey on Circulating Fluidized Bed Combustion Boilers Thenmozhi Ganesan 1 ,

Dr.Sivakumar Lingappan

14) Fluidized Bed Combustion As A Risk-Related Technology A Scope Of Some Potential

Problems.

15) Materials in Energy Conversion, Harvesting, and Storage By Kathy Lu.

16) Converting waste to energy through fluidised bed processing in CSIR Technology

transfer Portal.

17) W. M. Gao, L. X. Kong and P. D. Hodgson, “Numerical Simulation of Heat and Mass

Transfer in Fluidized Bed Heat Treatment Furnaces”, Journal of Materials Processing

Technology, vol. 125, (1997), pp. 170-178.

18) J. F. Davidson and D. L. Keairns, “Fluidization”, Proceedings of the Second Engineering

Foundation Conference, Trinity College, Cambridge University , (1978) April 2-6.

19) Modigell M., Traebert, A. and Weng, M. (1998), Incineration of contaminated waste in

fluidized bed with high temperature dedusting, CHISA'98, Prague, Czech Republic.

20) Verhoeff F. and Holtzer C.J.(1995), in Atmospheric Fluidized Bed Coal Combustion,

(Ed. M. Valk), Elsevier, Amsterdam, 1995, pp. 387-455.

37

21) Zevenhoven R., Yrjas P., Hupa M. (1999), in 15th Int. Conf. on Fluidized Bed

Combustion, Savannah, 16-19 Sept., USA, Paper No: Fluidised Bed Combustion 99-

0102.

22) A book on EPA Combined Heat and Power Partnership Biomass CHP Catalog.

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