Coke Oven Heating Regime

HEATING REGIME HEATING BY EITHER CO GAS OR MIXED GAS .

•AIR REQUIRED FOR COMBUSTION ENTERS AND WASTE GASES GENERATED ARE DISPOSED, THRU WHBOX by the DRAFT of CHIMNEY •AIR QUANTITY IS REGULATED WITH THE HELP OF FINGER PLATES, FLAP OPENING,LOWER BANANA,DRAFT DAMPER AND CHIMNEY GATES.

•CO GAS FROM NETWORK PREHEATED TO 65 DEG C AND SUPPLIED TO ALL 68 RISERS EACH ON P/S & P/S •EACH GAS RISER IS EQUIPPED WITH ISOLATION COCK & REVERSING COCK

WHAT IS REVERSAL • ONCE FOR EVERY 20 MTS HEATING CHANGES FROM GREEN TO RED (OR) RED TO GREEN TAKES PLACE WHICH IS CALLED – REVERSAL • THIS IS TO ATTAIN UNIFORM HEATING.

GREEN REVERSAL ODD FLUES OF ODD H/W & EVEN FLUES OF EVEN H/W

HEATING SYSTEM IN GREEN REVERSAL

1

OVEN 150

E O

O

H/W150

E

REG REG 149 149

H/W

H/W151

E E

O

HH

OVEN 151

H/W152

O E

E

REG REG 150 150

REG REG 151 151

WHB 150

WHB 151

REG REG 152 152

CONCRETE FLUE GAS TUNNEL

RED REVERSAL EVEN FLUES ODD H/W & ODD FLUES OF EVEN H/W

F L A S H

X

Y 10

C = X-(Y+10) = 159 – 165 mm = = 156 – 160 mm =

P L A T E T in case of F –Series T in case of D - Series

HEATING SYSTEM IN RED REVERSAL

1

OVEN 150

E O

O

H/W150

E

REG REG 149 149

H/W

H/W151

E E

O

HH

OVEN 151

H/W152

O E

E

REG REG 150 150

REG REG 151 151

WHB 150

WHB 151

REG REG 152 152

CONCRETE FLUE GAS TUNNEL

Flue connection in adjacent h/ws’ in one reversal(h/w –150 , 151)

H/w 150

H/w 151

Flue connection in G/R reversal

150

150

PAUSE • SMALL INTERMISSION PROVIDED AT CHANGEOVER FROM ONE HEATING TO ANOTHER • FACILITATES EVACUATION OF RESIDUAL GASES • 30 SECONDS IN BAT1&2 • 0 SEC. IN BAT3

REVERSING WINCH • Reversing winch mechanism is meant for • reversing the heating system from RED heating to • GREEN heating and vice versa to attain uniform • heating of the battery • This consists of a motor and gear box.

•Drives provided are electrical, and Pneumatic •Manual Provision is also given in case of total power failure •Minimum air pressure required forpneaumatic drive is 4 kg/sq.cm •All the WHBoxes and heating gas reversing cocks are connected to this system. •Condition of the ropes and pulleys is to be ensured.

INTERLOCKS OF REV. WINCH • To ensure the safety of the system, some interlocks are provided such that • Rev.winch goes to pause position (along with hooter) • when reg .draft in both the streams goes below 5mmwc • When h/gas pressure goes below 50mmwc • When air rope snaps • Rev. winch remains in the same position (but hooter comes) when gas rope snaps

AFTER REV COCK, SYSTEM IS BIFURCATED INTO TWO : RED & GREEN

•EACH SUB SYSTEM AFTER REV.COCK IS PROVIDED WITH A CYLINDER ADJUSTED IN ORIFICE

•THEN EACH SUB SYSTEM IS CONNECTED TO A MANIFOLD

•THE MANIFOLD IS CONNECTED TO THE FLUES BY RUBBER HOSE.

•OTHER END OF THE HOSE IS CONNECTED TO WASHER HOLDER AND RISER UNIT.

•FOR EACH FLUE, WASHER OF PRESCRIBED SIZE IS PROVIDED IN THE WASHER HOLDER •GAS FLOW FOR ENTIRE HALF SECTION OF H/W IS REGULATED BY CYLINDER. •GAS FLOW FOR EACH FLUE IS REGULATED BY WASHER

AIR ENTERS THRU WHB , BUS FLUE AND REGENERATOR CO GAS AFTER RISER UNIT • PASSES THRU CERAMIC RISER •AIR AND GAS UNDERGOES COMBUSTION

REGENERATOR • THE HEAT IN THE WASTE GAS IS ABSORBED by CHECKERS DURING DOWN- STREAM AND GIVEN AWAY to AIR DURING UPSTREAM

LOWER BANANA SCHEME P/S(mm) 1 2 3

4 5 6 7 8 9 10 11 12

13 14 15 16

00

35

35

35

35

35

35

35

00

34

32

30

28

26

24

22

00

34

32

30

28

26

24

22

00

35

35

35

35

35

35

35

LOWER BANANA SCHEME C/S(mm) 17 18 19 20 21 22 23 24 25 26 27

28

29 30 31 32

35

35

35

35

35

35

35

00

34

34

34

34

34

34

34

00

34

34

34

34

34

34

34

00

35

35

35

35

35

35

35

00

MEANS FOR FLAME LENGTH ADJUSTMENT • UPPER BANANA • DEFLECTOR • RECIRCULATION WINDOW • RESERVE BRICKS.

CONTROL VERTICAL TEMP(6/28 OR 9/23 MEASUREMENT TO BE STARTED 5 MTS AFTER REVERSAL MESUREMENT TO BE STARTED FROM 101 C/S UP TO 101 P/S IN A “U” FASHION

*MEASUREMENT

TO BE DONE IN “ NON – BURNING FLUE” *MEASUREMENT TO BE COMPLETED BY REVERSAL END.

CORRECTION FACTOR for CVT • VALID FOR A PARTICULAR CP • TO COMPENSATE THE DROP IN TEMP WITH TIME OF MEASUREMEN • BROADLY CLASSIFIED INTO 4 TEMP ZONES • STARTS FROM C/S 101 AND ENDS WITH P/S 101

• TEMP DIFF. BETN P/S AND C/S CONTROL VERTICALS IS 35-45 DEG C(1.5 DEG C BETN. ADJACENT FLUES) • DIFF. BETN. EVT&FLUE TEMP NEXT TO EV NOT TO EXCEED 30 DEG C •DIFF . BETN. EVT & CVT NOT TO EXCEED 100 DEG C.

CROSS WALL TEMP (CWT) (1-32 FLUES) • TAKE 10/11 H/WS’ AS ONE SET • MEASURE IN TOTAL 4 REVERSALS (5 H/WS’ IN 2REV • START MEASUREMENT FROM C/S AND MOVE IN AZIG-ZAG WAY

WASHER SCHEME ( H/WALLS-102 TO 167 / H/WALLS 101 ,168) 1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16

21.9

16.9

16.4

16.2

16.1

16.1

16.1

16.1

16.2

16.2

16.2

16.2

16.3

16.3

16.4

16.4

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 16.5

16.5

16.6

16.6

16.7

16.7

16.7

16.7

16.8

16.8

16.8

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16

21.4

17.1

14

13.5

13.4

13.4

13.4

13.5

13.6

13.6

13.6

16.9

13.6

16.9

13.7

17.3

13.7

18.8

13.7

22.3

13.7

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 13.7

13.7

13.8

13.8

13.8

13.8

13.8

13.8

13.9

13.9

13.9

13.9

14.7

15.5

19

22.6

END VERTICAL TEMP (1&32 VERTICALS) • MAX EVT- 1250/1300 DEG C

• EVT AT EXTENDED CP – 1140/1180 DEG C

COEFFICIENT OF BATTERY(KB) (indicates temp uniformity) • KB= (66-0p) + (66-0k) 2*66

= 1.0( ideal)

• 66 = no of h/ws’ considered • 0p= no of h/ws’ deviated from p/s day average temp by more than + 20 DEG.C • 0k = no of h/ws’ considered from c/s day average temp by more than +20 deg C

KC= no of avgs’ deviated by more than 7 deg c from the respective target total no of avgs’ in the day(6) Kc =6/6=1(ideal)

COEFF OF EXCESS AIR (theoretical 1.3) ALPHA = 1 + K (O2-0.5 CO) CO2+CO K for co gas – 0.42 K for BF gas – 2.59

FREE SPACE TEMP • This is the temp measured in the free space of the oven at 2/3 of coking period thru p/s and c/s charging holes with the help of the thermocouples. • This temp should be in the range of 780800 deg C.

•Higher FST results in cracking of aromatics and unwanted graphite deposition which affects tar fluidity and also gas track jamming. • lower FST results in non readiness of coke mass

CHARGE LEVEL MEASUREMENT • Coal level to be measured in the oven immediately after charging with the help of a tool provided exclusively for it. • The free space should be around 250-300 mm. • To be measured thru all three charging holes.

SHRINKAGE MEASUREMENT • It is measured in the oven thru all charging holes 15 mts before the end of coking period. • The shrinkage is 250-300 mm • % shrinkage = shrinkage in mm * 100 6700 mm(coal level after charging) • DESIRABLE VALUE= 5%(approx.) • less shrinkage results in more wall pressure • more shrinkage is the result of more volatile matter

DRAFT • Suction created by the chimney • Amount of suction created depends on chimney height, waste gas temp, climatic conditions etc. • Draft facilitates inletting of air and out letting of waste gases into atmosphere. • Draft is mantained with the help of chimney gates in auto mode.

•Indication for good draft is slightly positive pr.at vertical top, strong flame and alpha @1.3-1.4. •Draft should be uniform throught the battery for better temp uniformity •.Uniformity of draft is to be attained by regulating draft dampers at waste heat boxes atleast twice/month •Draft regulation is done with the help of INCLINTED MANOMETER.

VERTICAL TOP PRESSURE • VTP to be mantained as slightly positive so as to prevent infiltration of air into the system CROSS LEAKAGES • These are mainly raw gases from oven to heating system • cross leakages are the indication of bad refractory condition • Cross leakages always to be kept at check • High waste gas temp is the indication of cross leakages

OVEN SOLE PRESSURE GCM Pr. = Sole pr. + 1.2 h h = height betn. Oven sole and GCM( 10 mtrs in our case) Desired sole pressure= 0.51.0mm

COKE MASS TEMP • COKE MASS TEMP MEASURED THRU ALL CHARGING HOLES AT 4 LEVELS ALONG OVEN HEIGHT • MEASURED WITH THERMOCOUPLES INSERTED AT 7-8 HRS OF CP • DESIRABLE COKE MASS TEMP.AT 30 MTS BEFORE THE END OF CP- 1050 deg C

GENERAL PROBLEMS • • • • •

BUFFING: CHIMNEY CROSS LEAK: CHIMNEY SMOKING WHITE CHIMNEY PUMPS NOT WORKING WASTE GAS TEMP HIGH ETC…

***REASONS , INDICATIONS AND REMEDIES