2. Performance Evaluation of A Steam Generator P M V Subbarao Professor Mechanical Engineering Department A Measure of Efficient Combustion …..

3. First Law Analysis of Furnace at Site C X H Y S Z O K +  4.673 (X+Y/2+Z-K/2) AIR + Moisture in Air + Ash Moisture in fuel→ P CO 2 +Q H 2 O +R SO 2 + T N 2 + U O 2 + V CO + W C + Ash Mass of air:  *4.673* (X+Y/2+Z-K/2) *28.89 kg. Mass of Coal: 100 kg. Excess Air:  -1)  4.673* (X+Y/2+Z-K/2) *28.89 kg.

4. C X H Y S Z O K +  4.673 (X+Y/2+Z-K/2) AIR + Moisture in Air + Ash + Moisture in fuel→ P CO 2 +Q H 2 O +R SO 2 + T N 2 + U O 2 + V CO + W C + Ash

5. First Law Analysis of Furnace:SSSF Conservation of Mass: m fuel m air m fluegas Q Q W fans m ash First Laws for furnace in SSSF Mode:

6. Flue Gas Analyzer P s CO 2 +Q s H 2 O +R s SO 2 + T s N 2 + U s O 2 + V s CO

7. Measurements of Gas Analyser Dry Exhaust gases: P s CO 2 +R s SO 2 + T s N 2 + U s O 2 + V s CO kmols. Volume of gases is directly proportional to number of moles. Volume fraction = mole fraction. Volume fraction of CO 2 : x 1 = P s * 100 /(P s +R s + T s + U s + V s ) Volume fraction of CO : x 2 = V s * 100 /(P s +R s + T s + U s + V s ) Volume fraction of SO 2 : x 3 = R s * 100 /(P s +R s + T s + U s + V s ) Volume fraction of O 2 : x 4 = U s * 100 /(P s +R s + T s + U s + V s ) Volume fraction of N 2 : x 5 = T s * 100 /(P s +R s + T s + U s + V s ) These are dry gas volume fractions. Emission measurement devices indicate only Dry gas volume fractions.

8. Analysis of Ash & Measurement of UC

9. Measurements: Volume flow rate of air. Volume flow rate of exhaust. Dry exhaust gas analysis. x 1 +x 2 +x 3 + x 4 + x 5 = 100 or 1 Ultimate analysis of coal. Combustible solid refuse. nC X H Y S Z O K +  n 4.673 (X+Y/4+Z-K/2) AIR + Moisture in Air + Ash & Moisture in fuel → x 1 CO 2 +x 6 H 2 O +x 3 SO 2 + x 5 N 2 + x 4 O 2 + x 2 CO + x 7 C + Ash

10. Moisture due to Combustion air

11. Moisture due to fuel

12. nC X H Y S Z O K +  n 4.76 (X+Y/4+Z-K/2) AIR + Moisture in Air + Ash & Moisture in fuel → x 1 CO 2 +x 6 H 2 O +x 3 SO 2 + x 5 N 2 + x 4 O 2 + x 2 CO + x 7 C + Ash x 1, x 2,x 3, x 4 &x 5 : These are dry volume fractions or percentages. Conservation species: Conservation of Carbon: nX = x 1 +x 2 +x 7 Conservation of Hydrogen: nY = 2 x 6 Conservation of Oxygen : nK + 2 n  (X+Y/4+Z-K/2) = 2x 1 +x 2 +2x 3 +2x 4 +x 6 Conservation of Nitrogen:  n 3.76 (X+Y/4+Z-K/2) = x 5 Conservation of Sulfur: nZ = x 3

13. nC X H Y S Z O K +  n 4.76 (X+Y/4+Z-K/2) AIR + Moisture in Air + Ash & Moisture in fuel → x 1 CO 2 +x 6 H 2 O +x 3 SO 2 + x 5 N 2 + x 4 O 2 + x 2 CO + x 7 C + Ash Re arranging the terms (Divide throughout by n): C X H Y S Z O K +  4.76 (X+Y/4+Z-K/2) AIR + Moisture in Air + Ash & Moisture in fuel → (x 1 /n)CO 2 +(x 6 /n) H 2 O +(x 3 /n) SO 2 + (x 5 /n) N 2 + (x 4 /n) O 2 + (x 2 /n) CO + (x 7 /n) C + Ash C X H Y S Z O K +  4.76 (X+Y/4+Z-K/2) AIR + Moisture in Air + Ash Moisture in fuel → P CO 2 +Q H 2 O +R SO 2 + T N 2 + U O 2 + V CO + W C + Ash

14. Specific Flue Gas Analysis For each kilogram of fuel: Air :  4.76 (X+Y/2+Z-K/2) * 29.9 /100kg. CO 2 : P * 44/100 kg. CO : V * 28/100 kg. Oxygen in exhaust : 32 * U/100 kg. Unburned carbon: 12*12/100 kg.

15. Various Energy Losses in A SG Heat loss from furnace surface. Unburned carbon losses. Incomplete combustion losses. Loss due to hot ash. Loss due to moisture in air. Loss due to moisture in fuel. Loss due to combustion generated moisture. Dry Exhaust Gas Losses.

16. Heat loss from furnace surface. Unburned carbon losses. Incomplete combustion losses. Loss due to hot ash. Loss due to moisture in air. Loss due to moisture in fuel. Loss due to combustion generated moisture. Dry Exhaust Gas Losses ~ 4.5% Heat gained by superheater & reheater 40% Heat gained by economizer & air preheater 12% Fuel Energy 100% Heat gained by boiling water 40% Hot gas Flue gas

17. Energy Credits Chemical Energy in the fuel. Energy credit supplied by sensible heat in entering air (recycling of energy). Energy credit supplied by sensible heat in the fuel(Recycling of energy). Energy credit supplied by auxiliary drives.

18. Furnace Energy Balance First Laws for Furnace in SSSF Mode (in molar form):  Q +n air h air + n fuel h fuel =  n fluegas h fluegas +  W n fuel n air n fluegas Q Q W fans