combustion of liquid fuels - fluid.wme.pwr.wroc.pl

COMBUSTION AND FUELS

COMBUSTION OF

LIQUID FUELS


PHASES OF LIQUID FUEL BURNING

Two phases of liquid fuel burning:

a) phase of liquid evaporation,

b) phase of vapour burning.

Droplet of fuel

Cloud of vapour


DOMINATING FACTORS OF OIL COMBUSTION

- liquid evaporation,

- mixing of vapour and oxidizer (air),

- chemical kinetics of combustion in gas phase.

INFLUENCE OF GEOMETRY ON THE

COMBUSTION PATTERN

radiation

liquid fuelair

soot

diffusion

dropletof fuel

diffusionflame

air

droplets+air

evaporation

kineticflame

prze

wo

dze n

iec i

epła

10-6 10-5 10-4 10-3 10-2 10-1 1 10 102

size [m]

hea

t c

on

du

ctio

n


BURNING OF SINGLE OIL DROPLET

Diffusion model of single oil droplet combustion:a) flame geometry, b) temperature and fuel Cf /oxygen CO2 content

τs = kd02

oxidizer

products of combustion

droplet

vapour

vapouroxidizer

flame


TIME OF BURNOUT OF A SINGLE OIL DROPLET

Time of burnuot τs :

τs = kd02

do – initial diameter,

k – coefficient.


INFLUENCE OF FLOWFIELD ON THE

COMBUSTION PATTERN

1 2 3

a) Influence of natural convection, b) Influence of forced convection

(1 – flow, 2 – droplet, 3 – recirculation zone)

flame

gas flow

fumes

droplet

oxygen

fuel

border of heated area


INFLUENCE OF INNER ROTATION OF LIQUID ON

THE COMBUSTION PATTERN


Influence of droplet evaporation on the

combustion pattern


BURNING OF A SINGLE DROPLET OF HEAVY OIL

Four phases of combustion:

I – time of induction ignition – ended with ignition

of light fractions of oil,

II – burning – evaporation, cracking of heavy

fractions of oil, formation of coke shell,

III – micro explosion – destruction of coke shall,

IV – burnout of coke shall.


HISTORY OF A SINGLE DROPLET BURNING (part 1)


HISTORY OF A SINGLE DROPLET BURNING (part 2)


TEMPERATURE HISTORY OF A SINGLE DROPLET BURNING


COKE SHALE FORMATION AND RESIDUE

Coke shell

Shell formation

fuel droplet

coke shell

fragments of the broken coke shell


OIL-COKE MICROSCOPE PHOTO


PATTERNS OF OIL DROPLETS BURNING IN FLAME

Group combustion

diffusion flame


STRUCTURE OF DISPERSED

OIL FLAME


STRUCTURE OF DISPERSED OIL FLAME:

1D - MODEL

1 2 3 4

oil droplets+air

flow dirrection

fumes


STRUCTURE OF SPRAYED OIL FLAME

1 2 3 4 5

1 – stream of sprayed fuel, 2– zone of evaporation, 3 – zone of ignition,

4 – zone of combustion of individual droplets, 5 – boundary of flame


STRUCTURE OF SWIRLED OIL FLAME

airrecirculation

zone

oil spraying

zone


INFLUENCE OF SPRAY PATTERN

ON THE OIL-FLAME STRUCTURE


TWO TYPES OF SPRAY PATTERN: A – HOLLOW B – SOLID

HOLLOW CONE PLAME PATTERN

FULL (SOLID) CONE PLAME PATTERN

Structure

of swirled

oil flame


OIL BURNERS


COMPACT OIL BURNERS

Compact oil burner has three main units:

– oil atomisation,

– aerodynamics,

– control.


SCHEME OF COMPACT OIL-BURNER

fan

ignitiontransformer

ignitiontransformernozzle

ignition electrodes

head of burner

oil supply unit

oil filter

oil pump

oil pressureregulator

cut offvalve


EXAMPLE OF COMPACT OIL BURNER


COMPACT OIL BURNER INSTALLED IN A BOILER


HEAVY OIL BURNERS OF THE LANCE TYPE


HEAVY OIL LANCE BURNER FOR BOILERS START UP

1 − diffuser, 2 − lance, 3 − electric igniters − air box(P − steam, M − mazout, P1, P2 − primary and secondary air)

LANCE OF MAZOUT BURNER

steam oil


PARAMETERS OF MAZOUT AND STEAM

IN START-UP BURNER

Parameter Unit Value

Mazout pressure MPa 0.4 ÷ 0.6

Mazout temperature oC 115 ÷ 130

Steam pressure MPa 0.8 ÷ 1.0

Steam temperature oC 230

LOCATION OF MAZOUT BURNER IN SWIRL BURNER

MAZOUT BURNER IN BOILER FURNACE


SCANNER OF MAZOUT FLAME IN BOILER FURNACE

FIREYE InSight type 95


LAMP OIL BURNER

wick

combustion of liquid fuels - fluid.wme.pwr.wroc.pl

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