Benefits of an air preheater replacement. Benefits of an air preheater replacement unit in a large CDU furnace

Transcription

1 Benefits of an air preheater replacement unit in a large CDU furnace

2 Content 1) Existing situation 2) Design criteria 3) Replacement 4) Results

3 Content 1) Existing situation 2) Design criteria 3) Replacement 4) Results

4 Actual process flow Duty 13,9 MW 3 heaters B-Damper kg/h 445 C Stack kg/h 225 C APH-A APH-B Furnace 275 C

5 Furnace of 170 MW, 2 DEKA APH s with both 14 MW duty

6 Content 1) Existing situation 2) Design criteria 3) Replacement 4) Results

7 Check of design data according to operation FGI: 445 C FGO: 300 C O2 out of furnace: 3%, wet DT-Air: 190 C

8 Check of design data according to operation 170 MW

9 100% - Furnace efficiency in % Benefits of an air preheater replacement New flue gas exit temperature target for the new APH Stack temp. in C Furnace efficiency Lowering the stack temperature by 140 C would save about 7% fuel.

10 Check stack conditions, worst case 67 kg/s, 283 C 67 kg/s, 173 C Acid DP: 135 C 110m Draft: 6 mbar Acid DP: 135 C 110m Draft: 5 mbar 3 other heaters: C 1% H2S max. 300 C CDU4 heater 3 other heaters: 189 C 50 kg/s, 300 C C 100 ppm H2S 1% H2S max. CDU4 heater 50 kg/s, 154 C 100 ppm H2S BEFORE AFTER

11 Check ID-fan conditions With lower flue gas flow rate passing through ID-Fan, higher pressure increase can be used without reducing safety margin.

12 Design parameters of new APH Stack kg/h 445 C 7 mbar 154 C Furnace 364 C 5 mbar kg/h 16 C 16 C Combustion Air

13 Hot Air Recirculation for air preconditioning Stack kg/h 445 C 144 C Furnace 353 C kg/h 19 C -10 C 8 % HAR

14 Cold Air Bypass for performance adjustment Stack kg/h 475 C 183 C Furnace 352 C 389 C kg/h 16 C 10% CAB

15 Advantage of HAR vs. CAB For equal metal skin temperature, HAR offer 34 C hotter air, equivalent to 2,2 MW duty (difference between +25 and -10 C).

16 Air temperature, C Benefits of an air preheater replacement Advantage of HAR vs. CAB /11/ :00 07/11/ :00 09/11/ :00 11/11/ :00 13/11/ :00 15/11/ :00 17/11/ :00 19/11/ :00 21/11/ :00 Date Air inlet temperature is not depending of outside conditions, less fouling and less condensation in the air preheater. HAR AMB

17 Air Preheater selection Counter flow plates Fully welded High efficient Compact and light

18 Material selection Because of acid dew point being higher than the cold end metal temperature of the heat exchanger, a plate made from SS304 has been chosen: Cr-content: 17,0-18,5 % Ni-content: 8,5-10,5 % Cold end temperature approx. 83 C

19 Acid Dew point C Benefits of an air preheater replacement Material selection dew point consideration ,000 10,000 SO2 content, ppm ADP-10 Vol % H2O ADP-20 Vol % H2O Depending on H2S in the fuel (from few ppm to 100 ppm) the dew point can vary from 73 to 107 C (VDI 4760)

20 Content 1) Existing situation 2) Design criteria 3) Replacement 4) Results

21 Pre-assembly in largest possible components, with insulation

22 Transport by ship

23 Dismantling of old units within 3 days

24 Removal of the old DEKA-type APH: weight approx. 65 to.

25 Dismantling of old installation The old APH unit has been completely removed

26 Placing the new air plenum on the prepared structure requires a high degree of accuracy.

27 Installing the new APH: weight of only 42 tons with higher performance than the original.

28 Ready for start-upon the 1 st of November 2011

29 New APH Layout Benefits of an air preheater replacement

30 Content 1) Existing situation 2) Design criteria 3) Replacement 4) Results

31 Flue gas outlet temperature ( C) Benefits of an air preheater replacement Flue gas outlet temperature /10/ :00 13/11/ :00 03/12/ :00 23/12/ :00 12/01/ :00 01/02/ :00 21/02/ :00 Date Flue gas outlet temperature decreased from 310 C to 166 C

32 Air outlet temperature of APH, C Benefits of an air preheater replacement Hot air outlet temperature Average Temp before replacement /10/ :00 13/11/ :00 03/12/ :00 23/12/ :00 12/01/ :00 01/02/ :00 21/02/ :00 Date Hot air outlet temperature average of 356 C after start-up.

33 Heat efficiency oin % Benefits of an air preheater replacement Heater efficiency /11/ :00 08/11/ :00 13/11/ :00 18/11/ :00 23/11/ :00 28/11/ :00 03/12/ :00 08/12/ :00 13/12/ :00 Date Heater efficiency increase from 81,2% to 90,1%

34 Duty / Throughput, MW / m3/hr Duty / Throughput ratio 0.25 Benefits of an air preheater replacement /10/ :00 13/11/ :00 03/12/ :00 23/12/ :00 12/01/ :00 01/02/ :00 21/02/ :00 Date Duty / throughput ratio reduction from 0,126 MW/m3/hr by 22% to 0,098 MW/m3hr. (average throughput of 1110 m3/h)

35 NOX, corrected, mg/nm3 Benefits of an air preheater replacement NOx increase Limit Nox range in /10/ :00 13/11/ :00 03/12/ :00 23/12/ :00 12/01/ :00 01/02/ :00 21/02/ :00 Date NOx increase prediction to mg/nm3 in line with API 535, fig. 9. Then back to range of mg/n3 after burner adjustment. 2011

36 Summary Reduction of the flue gas outlet temperature by 144 C. Increased of Air temperature to burners by 151 C. Increase of heater efficiency by 8,9% point. Reduction of duty/throughput ratio by 22% (0,028 MW/m3/hr) Saving of approx. 10,1 MW at current average heater duty of 114 MW. CO 2 saving of to/year Fuel saving of 855 Nm3/h. Payback less than 2 years based on fuel saving based on current average firing duty.

37 Questions?

38 Thank you for your Attention BD-Heat Recovery Inc. Dr. Olivier Brasseur