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

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

GREEN REVERSAL

ODD FLUES OF ODD H/W &

H/W REG 150 REG 151 WHB 151 REG 151 REG 152 OVEN 151 HH REG 150 REG 152 1 OVEN 150 WHB 150 REG 149 REG 149

CONCRETE FLUE GAS TUNNEL E E

E E O O O O E E

H/W150 H/W151 _H/W152

RED REVERSAL

&

X

Y

10

C = X-(Y+10) = 159 – 165 mm = T in case of F –Series = 156 – 160 mm = T in case of D - Series F L A S H P L A T E

H/W REG 150 REG 151 WHB 151 REG 151 REG 152 OVEN 151 HH REG 150 REG 152 1 OVEN 150 WHB 150 REG 149 REG 149

CONCRETE FLUE GAS TUNNEL E E

E E O O O O E E

H/W150 H/W151 _H/W152

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

150 150

PAUSE

• SMALL INTERMISSION PROVIDED AT

CHANGEOVER FROM ONE HEATING TO ANOTHER

• FACILITATES EVACUATION OF

RESIDUAL GASES

• 30 SECONDS IN BAT1&2

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

•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 :

•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 UP- STREAM

LOWER BANANA SCHEME P/S(mm)

LOWER BANANA SCHEME C/S(mm)

MEANS FOR FLAME

LENGTH ADJUSTMENT

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

•

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

WASHER SCHEME

END VERTICAL TEMP

(1&32 VERTICALS)

• MAX EVT- 1250/1300 DEG C

• EVT AT EXTENDED CP – 1140/1180

COEFFICIENT OF BATTERY(KB) (indicates temp uniformity)

• KB= (66-0p) + (66-0k) = 1.0( ideal)

2*66

• 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

KC= no of avgs’ deviated by

more than 7 deg c from the

respective target

total no of avgs’ in the day(6)

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 780-

•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

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

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

•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

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=

0.5-1.0mm

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

GENERAL PROBLEMS

• BUFFING:

• CHIMNEY CROSS LEAK:

• CHIMNEY SMOKING WHITE

• CHIMNEY PUMPS NOT WORKING • WASTE GAS TEMP HIGH ETC…

***REASONS , INDICATIONS AND REMEDIES