4a. Boiler Efficeny Evaluation

Boiler Efficiency Evaluation Efficiency Facts • Combustion Efficiency (Burner) • Heat Transfer Efficiency (Surface area) • Boiler Efficiency (Total System Efficiency)

Fuel 100%

Flue Gases 18%

Steam 75%

Boiler Efficiency

Boiler Efficiency=75% Shell Losses 2%

Ash Unburnts 2%

Blow Down 3%

Efficiency Evaluation Method Direct Method • Measurement of steam & Fuel flow only • Approximate Result

Indirect Method • Measurement of Temp, Pr, Fuel/Flue gas analysis, • More accurate result • Heat Loss Method • ASME/IS

DIRECT METHOD Boiler Efficiency =

=

(Steam Flow)

Enthalpy)

Output X 100 Input X (Steam Enthapy- F W

-----------------------------------------------------------------(Fuel Flow X GCV)

OR

Boiler Efficiency =Evap.Ratio X Steam Enthalpy

INDIRECT METHOD (As per IS: 8753)

Various Boiler Losses 1. Heat Loss in Dry Flue Gases 2. Heat Loss Due to Moisture and Hydrogen in the Fuel 3. Heat Loss Due to Moisture in the Air 4. Heat Loss Due to Carbonmonoxide in Flue Gases

5. Surface Heat Loss Due to Radiation 6. Blowdown Losses

CONTROLLABLE & UNCONTROLLABLE LOSSES

Boundary barrier Balance

Steam process

Fuel tank

179.c stack

5200kg/hr,120 .c

400kg/hr 30.c

4680kg/hr 520 kg.hr water 10% makeup water

Boiler

320.c

APH 30.c

Measurements required for thermal energy Audit in Boiler  Fuel flow, steam/water flow  Temp & Pressure of steam  Temperature of water inlet / outlet of economizer  Draught  CO2, O2, CO , Temperature from Flue Gas  Surface Temp & Ambient Temp  Surface Area, m2  Size & dimension of boiler

Test Procedure • • • • • •

Plan / inform the concerned dept. All the Instrument should be calibrated Ensure fuel and water availability Test at maximum steam load condition Conduct 8 hrs minimum (1/2 or 1 hr frequently) Water level in drum should be same at start & end of test • Gas Sampling point should be proper • No blow down during test

Requirements in boiler • • • •

Oil level in tank Water level in Service Tank No leakage water No blow down

• Boiler Testing Sheet • Fuel Analysis Report • Boiler Technical Specifications

Fyrite kit

CO2, O2 in flue gases

Combustion analysers

Contact thermometer

Infrared thermometer

RPM measurement

Tachometer

Stroboscope

BOILER PERFORMANCE TESTING Date : 8/2/2001 Time Fuel Feeder rpm

Steam Pressure - 5 to 7 kg/cm2 ID PA SA (Damper position opening)

ID PA SA (Power management) KW

O2

CO CO2 Temp (Flue gas analysis)

Temp

11:00 AM

21

100%

40%

50%

22

8

1.9

14.2

307

5.1

125

29

11.30 AM

30

50%

20%

30%

20.6

6.96

1.9

9.8

16

8.3

126

30

* At normal operatiing condition, power and flue gas measurement were taken Then, excess air reduced by closing damper in all FD and ID secondary air fan Fuel feeding rate is increased from 21 rpm to 30 rpm Again power and flue gas measurement were taken Suggesions : 1) Keep furnace draft + 5mm 2) Flue gas should be light gray at chimny top 3) keep Lowest possible damper position

Boiler Calculations