e1a - flame stability
DESCRIPTION
experiment for combustionTRANSCRIPT
COMBUSTION ENGINEERING & GAS UTILISATION LABORATORY
SKN 4721
Title of Experiment
FLAME STABILITY
DEPARTMENT OF GAS ENGINEERING
FAC. OF PETROLEUM AND RENEWABLE ENERGY
ENGINEERING
UNIVERSITI TEKNOLOGI MALAYSIA
Group
Group Leader
Members 1.
2.
3.
4.
Technicians / Teaching Assistants
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1. INTRODUCTION
A stable flame indicates that the design and operational
characteristics of a burner is highly effective. The flame stability
is important for a complete combustion to occur as well as to ensure
the burner is operated in a safe condition. The design and size of the
burner orifice and the capability to control the flows of fuel gas and
air are among the major factors that influence the flame stability. A
simple and very useful method of investigating flame stability is to
observe flame behaviours, i.e. flashback, yellow tipping or blow-off /
flame lift, under different operating conditions. The stability limits
are then plotted on a graph whose axes are air/gas ratio and thermal
input or burner port loading. This stability diagram is known as fuidge
diagram
2. LEARNING OBJECTIVES
At the end of this experiment, students will be able to
1. study the effect of burner size on the flame stability
characteristics.
2. develop curves/diagram demonstrating the limits of combustion
stability for different thermal inputs and sizes of burner port.
3. relate the effect of primary aeration on burner stability for
different burner inputs and port loadings.
4. explain the method of improving flame stability limits.
5. perform equipment safety assessment analysis
3. APPARATUS
Flame Stability Unit (PA Hilton) - The Flame Propagation and Stability
Unit is a bench top unit containing an air pump and fitted with two
variable area flow meter for air and gas. The unit comes with four
different sizes of tube burners, equipped with cone stabilizer and
glass tube with adapter. For the flame speed experiment, the unit
comes with two adapters with flame tap and an ignition spark plug. To
ensure safety during experiment, the safety foot valve is provided.
Fuel – Liquefied Petroleum Gas (LPG)
4. EXPERIMENTAL PROCEDURE
Important Note:
Prior to carrying out the experiment, students are required to perform
equipment risk analysis and fill up a laboratory safety assessment
form.
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General Start-up Procedure
1. Switch on the air blower. Open the air control valve and ensure air
flow is through to burner block.
2. Place foot on switch pad and open gas control valve and ignite
mixture on mixing tube, using a gas lighter.
3. Actual quantities to give good light – up will be found by
experience as they vary with different tubes and gases in use.
General Shut-down Procedure
1. To extinguish the flame, turn off the gas valve and purge the
system with air for a few seconds.
2. When finished with unit, isolate electrical and fuel supplies.
Flame Stability
1. Install a 22 mm diameter burner port to the main flame stability
unit
2. Switch on power for the main unit.
3. Switch on the air blower.
4. Open the air valve and allow the air to flow through the unit for a
few minutes.
5. Open the fuel gas valve and ignite the gas mixtures with an
igniter.
6. Adjust the fuel valve to obtain a stable flame
7. Using a ruler, measure the height of the flame cone
8. Adjust the air valve to observe the conditions of yellow tipping
(YT), lift off (LO) and light back (LB).
9. Place a piece of wire mesh on the burner port which as flame
stabilize and repeat procedures 6-8
10. Repeat procedures 6-8 for another two readings.
11. Repeat the experiment by using different burner tube diameters
(16mm & 13 mm)
5. DATA ANALYSIS
Using the flow conversion chart in Figure 1.0, determine the actual
volumetric flow rate of the air and fuel for observed flame behaviors,
and then estimate the corresponding air/fuel ratio. Calculate the
corresponding burner port loading, i.e. burner input per square meter
of port area (kW/m2)
Burner input, Q = fuel rate (m3/s) x fuel calorific value (kJ/m3)
Port area = Atube
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Burner loading = Q/Atube (kW/m2)
Tabulate the experimental results as follows;
Without stabilizer
Tube
Dia.
Thermal or
burner input Burner port
loading Air/Fuel Ratio (mol/mol)
(mm)
(kW) (kW/m2) YT BO LB
With stabilizer
Tube
Dia.
Thermal or
burner input Burner port
loading Air/Fuel Ratio (mol/mol)
(mm)
(kW) (kW/m2) YT BO LB
6. REPORTING OF RESULTS
i. Develop the fuidge diagram (air/fuel ratio (mol/mol) vs burner port
loading (kw/m2)) to demonstrate the light back (LB), blow-off (BO)
and yellow tipping (YT) zones for burner port with and without a
flame stabilizer, respectively.
Your write-up should also include discussion of
i. the effect of changing the primary aeration at a constant value of
burner port loading on the flame stability limits.
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ii. the effect of burner port area at a constant value of primary
aeration on the flame stability limits.
iii. the effect of the presence of wire mesh on the flame stability limits.
Support discussion with your observation made on the flame behaviour
and the fundamental knowledge of combustion (i.e. combustion
efficiency, combustion emissions, flame velocity etc)
iv. factors contributing to the inaccuracy of the experimental results
v. the safety aspects of the burner operation with respect to flame
control
EXPERIMENTAL DATA (WITHOUT WIRE MESH)
Tube
Dia.
Fuel gas flow
rate
Air flow rate
(from column)
(cm/s)
Air flow rate
(from calibration
graph)
(m3/s)
(mm)
from
column
(cm/s)
from
calib-
ration
graph
(m3/s)
YT BO LB YT BO LB
22
16
13
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Types of flame Observation (e.g. length of primary zone,
location of flame, etc)
Yellow tipping
Blow off / flame lift
Flash back
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EXPERIMENTAL DATA (WITH WIRE MESH)
Tube
Dia.
Fuel gas flow
rate
Air flow rate
(from column)
(cm/s)
Air flow rate
(from calibration
graph)
(m3/s)
(mm)
from
column
(cm/s)
from
calib-
ration
graph
(m3/s)
YT BO LB YT BO LB
22
16
13
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Types of flame Observation (e.g. length of primary zone,
location of flame, etc)
Yellow tipping
Blow off / flame lift
Flash back
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