Faculty of Chemical & Natural Resources Engineering

BKG3741 Gas Engineering Lab

Experiment 3COMBUSTION LAB UNIT -

GAS BURNER

NameMatric No.GroupProgramSectionDate

Sem. 11 - Session 2012/2013

BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

INTRODUCTION - C492 COMBUSTION LABORATORY UNIT

This unit enables studies into many aspects of combustion and burner operation using the optional burners or any suitable commercially available oil or gas burner up to 150 kW.

The four large observation windows fitted in the frame mounted, water cooled, combustion chamber provide an excellent flame demonstration facility. The full instrumentation and safety features allow supervised student operation over a wide range of air/fuel ratios and different fuels.

Figure 1: C492 Combustion Laboratory Unit

1.0 OBJECTIVESInvestigation Of Air/Fuel Ratio and Stoichiometric Condition.

Any hydrocarbon fuel has a condition of perfect combustion, in which the oxygen is consumed. The stoichiometric air/fuel ratio is different for each fuel depending on its chemical composition. This experiment is to set the burner to a mid range of fuel flow, which remains constant, and then alter the air/fuel ratio throughout the range possible to achieve combustion.

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BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

2.0 GENERAL DESCRIPTION

2.1 Unit Construction

Figure 2: Control Panel Layout C492

1. Main Switch 8. Water Flow Switch2. Burner Power Supply 9. Water Outlet Temperature3. Burner On 10. Water Temperature

Control4. Burner On/Off 11. Water Temperature

Control5. Burner Lockout 12. Oil Flowmeter6. Temperature Indicator 13. Gas Flowrate Timer7. Cooling Water Flowmeter

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BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

Figure 1: C492 Combustion Laboratory Unit

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BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

3.0 OPERATING PROCEDUR – GAS & OIL BURNER

3.1 OPERATING PROCEDURE – GAS BURNER

3.0 OPERATING PROCEDURE – GAS BURNER

3.1 SETTING UP GAS BURNER

1. Fit the gas burner onto the four mounting studs with four M8 nuts. Ensure the gasket is not overtighten ( just more than finger tight).

2. Connect and screw the 7 pin plug to the burner power socket.

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BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

3. Remove the blanking cap and screw the flexible hose coupling to the isolating valve end.

4. Connect the square plug onto solenoid valve.5. Connect pressure manometer tube to outlet pressure of

multibloc valve.( opened the tapping screw a turn)6. On multibloc valve, screw to fully anti-clockwise

(minimum), then back 2 turns.

3.2 STARTING THE GAS BURNER

1. Switch on the main isolator and main switch on the panel. ( Instrumentation should light)

2. Turn on main isolating valve and the valve at rear unit for water supply. Slowly turn the cooling water flow control anticlockwise until 200 g/s. Both two lamps change to green.

3. Ensure to set the dial of the water temperature control at 80˚C or above.

4. Turn on main isolating valve and lever isolating valve at rear unit to supply gas. ( Not more than 2 bar, 50 mbar NG).

5. Open the lever isolating valve at front of the unit (Check reading is 0 mbar)

6. Set the burner air control damper at position no 1-2.7. Press the green burner on/off button 1. The blower

starts to air purging the combustion chamber.8. After air purging, the pressure on the pressure

manometer should rise to the start level and the green burner will illuminate. If no ignition, press burner reset button to repeat the ignition.

9. Adjust the gas pressure control screw of the gas flow. Adjust the burner air control damper for the air flow.

3.3 EMERGENCY STOP FOR THE GAS BURNER

1. Press the red burner on/off button O on the control panel.

3.4 SHUTTING DOWN THE GAS BURNER

1. Turn off the main isolator valve . Allow the burner to fire until the flame goes out.

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BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

2. Press the red burner on/off button O on the control panel.

3. Ensure all isolating valves are shut.4. Turn off the water flow at cooling water flow valve,

water isolating valve and at main valve.5. Switch off the unit at main switch on the control panel.

Ensure the valve at the gas cylinder is closed. Place the cylinder at the designated area.

4.0 Safety Measures

Unit should be operated in a well ventilated area and sited well away from inflammable or heat sensitive material.

Do not allow the unit to run with the gas control valve open if no flame has been established.

The gas burner control system is more complex than the oil burner due to potentially hazardous and explosive nature of the fuel. Special care need to be taken during handling this system.

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RESULTS

C492- OBSERVATIONS GASDate: Fuel: Stoichiometric A/F: (by volume) Density of Gas: (kg/m3)Burner:Ambient Pressure: (mbar) Stoichiometric A/F: (by mass) Ambient Temperature: (C)

TEST NO. 1 2 3 4 5 6 7 8 9 10Gas Pressure (cm H20)Fan Damper Setting (No)Gas Flow Rate Timer (sec)Cooling Water Flowrate (g/s)Cooling Water Inlet Temp. t1 (C)Cooling Water Outlet Temp. t2 (C)Air Inlet Temperature t3 (C)Exhaust Temperature t4 (C)O2 (%)CO2 (%)CO (ppm)Excess Air (%)Flame Temperature t5 (C)Flame Color Flame Length (cm)Efficiency Nett (%)

BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

C492- DERIVED RESULTS GASDate: Fuel: Stoichiometric A/F: (by volume) Density of Gas: (kg/m3)Burner:Ambient Pressure: (mbar) Stoichiometric A/F: (by mass) Ambient Temperature: (C)

TEST NO. 1 2 3 4 5 6 7 8 9 10Gas Flow Rate (by Volume) (m3/Hr)Air/Fuel Ratio (by Volume) (vol/vol)Air Flow Rate (by Volume) (m3/Hr)Gas Flow Rate (by mass) (kg/Hr)A/F Ratio (by mass) (kg/kg)Air Flow Rate (by mass) (kg/Hr)Heat Input (Qin ) (kW)Flue – Useful a (kW)Flue – Unburnt b (W)Flue – Vapor c (kW)Total Heat to Flue (kW)d= (a+b+c)Heat to Water e (kW)Heat Output (Qout) =(d+e) (kW)Difference (Qin –Qout)/Qin (%)

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6.0 EXPERIMENT

6.1 Procedure for Gas Burner:1. Start the gas burner firing.2. Set the gas outlet pressure on the manometer

(approximately 80 kW heat input) (propane, 112 sec; Natural gas, 37 sec on Gas Flowrate Timer).

3. Adjust the cooling water flow and then keep it constant for temperature between 60 and 80 ˚C.

4. Adjust the air damper to the minimum which sustain combustion

5. Allow conditions to stabilize and record the readings on the observation sheet.

6. Increase the air damper position by one graduation.7. Again, allow the condition to stabilize and record the

readings.8. Increase the air flow in stages until maximum setting is

reached or combustion cannot be sustained.9. Shut down the burner.

10. Process the readings as given on the Derived Results Sheet.

The O2, CO2 and CO values are obtained from the standard air analyzer supplied.

6.2 Analysis & Discussions:1. Plot the graphs for Excessive Air (%) Vs. 02 and CO2(%).2. Complete the calculation in the tables for both mass and

volume. 3. Comments on the finding of the air/fuel ratio for the

combustion.

Sample Calculation

BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

Gas Flow Rate (Volume)

Air Fuel Ratio (Volume) Stoichiometric A/F by volume = 24 : 1Excess Air ( ) = 49.7 % ( from Analyzer)

Air Fuel Ratio (Volume) = 35.93 : 1

Air Flow Rate (Volume)= Gas Flow Rate x A/F vol

Gas Flow Rate (Mass)= Volume Gas Flow Rate x Density of Fuel

Air Fuel Ratio (Mass)= 15.6 : 1

Air Fuel Ratio (Mass) = 23.35: 1

Air Flow Rate (Mass)= Gas Flow Rate x A/F vol

Heat Input= Mass Gas Flow Rate x Gross Calorific Value (Fuel)

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Attachment

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BKG3741 – Fuel and Combustion Lab Sem II-2012/2013

Fuel Stoichiometric A/F by Volume

Stoichiometric A/F by Mass

Theoritical Maximum CO2 (%)

Gross Calorific Value (MJ/Kg)

Chemical Formula

Natural Gas

9.81 : 1 17.16 : 1 11.8 55.00 CH4

Propane 24 : 1 1.6 : 1 13.8 50.00 C3H8Butane 30 : 1 14.8 : 1 14.1 49.5 C4H10Kerosene 9.48 : 1 14.7 : 1 15.4 46.2 -Gas Oil 9.82 : 1 14.4 : 1 15.4 45.5 -

Conversion Factor10 mm H20 = 1 cm H20 = 1 mbar1 ft3 = 0.02832 m3

1 Imperial gallon = 4.546 Litre1 US gallon = 3.785 Litre

Oil Flowmeter Correction Factor = Display x 1.1 ( Kerosene)= Display x 1.0 (Gas Oil)

Cpg for Exhaust gas taken as 1.15 kJ/kgK ( for 750 EC)

Typical Values of density (Kg/m3)

Item DensityKerosene 790Gas Oil 835Propane 1.85Butane 2.45Natural Gas 0.68

Molecular Weight of O2 = 32Molecular Weight of H2 = 2Molecular Weight of C = 12Molecular Weight of N2 = 28Molecular Weight of H2O = 18

Air = 79 % N2, 21 % 02 ( by volume) 76.7 % N2, 23.3 % O2 (by mass)

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