COKE OVEN OPERATIONS - library.aimehq.orglibrary.aimehq.org/library/books/Ironmaking Proceedings 1976... · COKE OVEN OPERATIONS TUESDAY AFTERNOON, MARCH 30, 1976 The session on Coke

COKE OVEN OPERATIONS TUESDAY AFTERNOON, MARCH 30, 1976

The session on Coke Oven Operations convened at 2:30 pm. The chairmen were:

J. E. Ludberg J. G. Price Dofasco Dravo Corp. Hamilton, Ont., Canada Pittsburgh, Pa.

DESIGN, CONSTRUCTION AND START-UP OF

UNITED STATES STEEL'S NO. 2 COKE. BATTERY

AT GARY WORKS

Wilbur L. McHenry Div i s ion Super in tendent , Coke & Chemicals

Robert L. Land A s s i s t a n t D iv i s ion Superintendent , Coke & Chemicals

Andrew Fernandez, J r . S t a f f Engineer, Coke & Chemicals

United S t a t e s S t e e 1 Corporat ion, Gary Works Gary, Ind iana

~ a r y Works' No. 2 Coke B a t t e r y (F igure I ) , t h e second high c a p a c i t y - 6 meter -

(20 f t . ) u n i t a t Gary, was placed i n ope ra t i on on August 22, .1975. Included i n t h i s cons t ruc t ion p r o j e c t , i n a d d i t i o n t o t h e b a t t e r y block, coke quenching and sc reen ing f a c i l i t i e s and f l u sh ing l i q u o r processing. f a c i l i t i e s . (F igure 2), was a c o a l p rehea t ing p l a n t and cha in conveyor charging f a c i l i t i e s . A coke s i d e shed is a l s o included bu t t h e completion has been delayed pending c u r r e n t review of r e s u l t a n t environmental, s a f e t y and h e a l t h cond i t i ons .

The desfgn and d e t a i l , engineer ing of t h e b a t t e r y block, a s we l l a s most b a t t e r y a u x i l i a r i e s , was by Firma C a r l S t i l l of Recklinghausen, West Germany. The b a s i c des ign of t h e Precarbon Process Coal P rehea t ing and Charging P l a n t was provided by Bergwerksperband GMBH of West Germany, wi th d e t a i l engineer ing by both Finna C a r l S t i l l and United S t a t e s S t e e l Engineering. This is t h e f i r s t Car l S t i l l b a t t e r y t o be cons t ruc t ed and placed i n ope ra t i on on t h e North American Continent .

Const ruc t ion began wi th ground breaking i n mid-November 1973 and t h e b a t t e r y was placed i n ope ra t i on 21 months l a t e r . United S t a t e s S t e e l was t h e Cont rac t Adminis t ra tor handl ing a l l m a t e r i a l purchases a s we l l a s d i r e c t i n g t h e work of a consortium of c o n t r a c t o r s , subcont rac tors and American Bridge D.ivision.

The b a t t e r y i s comprised of 57 ovens, each 6.2 meters (20.3 f t . ) h igh x 46 cen t imeters (18 inches) wide x 14.6 meters (47.8 f t . ) long between door plugs. -The oven t a p e r is 8.9 cen t imeters (3% inches) , t h e e f f e c t i v e oven working volume 38.9 cubic meters (1374 cubic f e e t ) and t h e annual r a t e d coke c a p a c i t y 817,000 m e t r i c tons (900,000 s h o r t t ons ) . The b a t t e r y can be charged wi th wet c o a l o r wi th pre- heated c o a l prepared i n a newly cons t ruc ted "Precarbon P l an t " which w i l l be descr ibed l a t e r i n t h e paper .

The new b a t t e r y was e r ec t ed ad j acen t t o Gary No. 1 Ba t t e ry which was placed i n ope ra t i on i n 1970, s o t h a t t h e two b a t t e r i e s could s h a r e common s p a r e pusher machines, door 'machines and coke guides . Also, t h i s l o c a t i o n provided t h e f l e x i - b i l i t y of u t i l i z i n g No. 1 Ba t t e ry coa l tank and l a r r y c a r s f o r wet charging of B a t t e r y No. 2. This f e a t u r e allowed t h e b a t t e r y t o go i n t o product ion i n August 1975, even though t h e coa l ' p rehea t ing and cha in conveyor charging system was no t

1. View of No.' 2 Bat tery from pusher s i d e .

2. View of No. 2 Bat tery top and Charging Conveyors.

INSPECTION HOLES

OAS OF f -TAKE

HORIZONTAL

M I A T I N O CLUES

RIOENERATO

O U N N l T l WASTl H I A T CANALS L(,RlcAsT ARC?WAYS l WALLS)

3 . Typical s e c t i o n through Bat te ry .

,-.LEAN GAS 6

THRU FLUE AND DIVIDER LONGITUDINAL SECTION THRU ,

HEATING WALL

4; Sec t ions through Heating Walls.

490

ready f o r s t a r t - u p .

The hea t ing system des ign of a Ca r l S t i l l Bat te ry (F igure 3) is t h e h a l f divided-gun f i r e d type wi th t h e unique S t i l l mu l t i s t age burning. The h a l f divided design has been used f o r many years . I n t h i s design t h e gas burns on t h e pusher s i d e f o r 20 t o 30 minutes then r eve r se s and burns on t h e coke s i d e f o r 20 t o 30 minutes.

There a r e 17 f l u e s on t h e pusher s i d e and 14 f l u e s on t h e coke s i d e . Tradi- t i o n a l l y S t i l l B a t t e r i e s a r e designed wi th only 2 more f l u e s on t h e pusher s i d e than on t h e coke s ide , bu t with t h e United S t a t e s S t e e l Design requirement f o r a 8.9 cent imeter (3% inch) oven t ape r , an a d d i t i o n a l pusher s i d e f l u e was necessary t o balance t h e hea t d i s t r i b u t i o n between s i d e s . The b a t t e r y can be f i r e d with , e i t h e r coke oven o r b l a s t furnace gas.

Even though t h e bas i c hea t ing system is we l l known throughout t h e indus t ry , t h e r e a r e a number of unique f e a t u r e s t h a t s e p a r a t e t h i s b a t t e r y from t h e normal or b a s i c des i gn.

The waste heat cana l s a r e loca ted under t h e b a t t e r y pad. There a r e s i x arched passageways f o r c o l l e c t i n g t h e waste gases from t h e regenera tors and con- duc t ing them t o a common waste h e a t cana l a t t h e end of t h e b a t t e r y where t h e gases then t r a v e l t o a s t a c k which is 106.7 meters (350 f t . ) high. The s i x waste h e a t cana ls a r e s o designed t h a t each c o l l e c t s t h e gases from 10 regenera tors which, i n e f f e c t , is t h e waste gas from a s i x t h of t h e ba t t e ry . Of s i g n i f i c a n t i n t e r e s t h e r e i s t h a t t h e waste h e a t cana l wa l l s and archways were formed of pre- c a s t concre te s e c t i o n s . A f t e r a l l t h e p r e c a s t s e c t i o n s were i n place, t h e exposed conc re t e i n t h e waste h e a t duc ts was Gunited.

The r egene ra to r s o l e f l u e s a r e cons t ruc ted s o t h a t from t h e ou t s ide t o t h e c e n t e r t h e r e is a gradual decrease i n a r e a . A s i s t h e normal custom, t h e open- ings i n t h e s o l e f l u e roof a r e s i zed d i f f e r e n t l y from o u t s i d e t o i n s i d e t o regu- l a t e a i r and gas flow t o and from t h e regenera tors . Also, t h e regenera tor cham- be r s a r e divided l o n g i t u d i n a l l y and s e c t i o n a l i z e d t o f u r t h e r improve t h e d i s t r i b u - t i o n of a i r and waste gas t o and from t h e var ious f lues . J u s t above t h e s o l e f l u e roof t h e r e is a channel provided i n t o which d i f f e r e n t l y s i z e d pe r fo ra t ed p l a t e s o r b r i cks can be i n s t a l l e d , i f necessary, t o r e a d j u s t flow. To da te , t h e use b f t h i s a d d i t i o n a l r e g u l a t i o n has not been necessary.

The r i c h gas flows t o a row of f l u e s through a common gas gun and tapered duc t . The duc t is i n s u l a t e d t o avoid overheat ing and decomposition of t h e gas. The gas supply l i n e t o each gun i s f i t t e d with an exchangeable o r i f i c e t o regu- l a t e gas flow. I n add i t i on , each hea t ing f l u e conta ins an exchangeable r i c h gas p o r t nozz le b r i c k t o c o n t r o l gas flow.

L C

The most unique f e a t u r e of t h e S t i l l hea t ing system i s t h e mul t i - s t age heat- ing (F igure 4 ) . Unlike o t h e r systems, t h e mixing and burning of t h e f u e l gas w i th t h e combustion a i r t akes p l a c e a t s i x d i f f e r e n t l e v e l s i n t h e hea t ing f l u e s . When opera t ing wi th r i c h gas, t h e gas e n t e r s a t t h e bottom of t h e f l u e while t h e combustion a i r passes through duc t s i n t h e b o t t l e b r i c k s of t h e d i v i d e r wal l s , e n t e r i n g t h e f l u e from bo th s i d e s a t s i x l e v e l s . When opera t ing wi th l ean gas, bo th t h e gas and combustion a i r pass through t h e duc ts i n t h e d i v i d e r w a l l s en t e r - i ng t h e f l u e from oppos i te s i d e s a t t h e s i x l e v e l s . This f e a t u r e provides even h e a t i n g and combustion throughout t h e he igh t of t h e hea t ing wal l .

Another advantage r e s u l t i n g from t h i s des ign is t h a t , w i th t h e d i v i d e r wa l l duc t s having openings i n t o t h e f l u e s on e i t h e r s i d e of t h e wall , i t is only neces- s a r y t o have a duc t from one s i d e of t h e r egene ra to r f o r every o t h e r f l ue . here-

ADJUSTING SPRINGS

5. Oven Door Elevation and Section.

, ,

COMPRESSION

6 . Sect ion through Oven Door and Jamb.

fore , t h e r e a r e only h a l f t h e number of a i r p o r t s i n t h e co rbe l a r e a of a S t i l l b a t t e r y a s compared t o o t h e r b a t t e r y designs.

. Waste gases from t h e burning f l u e s a r e c o l l e c t e d i n a common hor i zon ta l f l u e . This f l u e , r a t h e r than being a l a r g e r ec t angu la r duct , is octagon shaped f o r increased s t a b i l i t y of t h e wa l l i n t h i s a r ea . Each v e r t i c a l f l u e has a s l i d i n g b r i c k i n t h e ho r i zon ta l f l u e which can be ad jus ted t o r e g u l a t e and balance c ross- wa l l temperatures.

The w e n door chosen f o r t h i s b a t t e r y (F igure 5) was a design which had been developed on Gary No. 1 Bat te ry . The door body i s a deep, heavy s e c t i o n c a s t i n g onto which is bo l t ed a s p r i n g loaded pan type s e a l i n g s t r i p (Figure 6 ) . The sea l - i ng pan is carbon s t e e l except f o r t h e s e a l i n g s t r i p i t s e l f which i s type 316 s t a i n l e s s s t e e l wi th a Rockwell hardness between C28 and C35. The s e a l i n g s t r i p compression sp r ings a r e a l s o s t a i n l e s s s t e e l bu t i n t h i s case type 301. The door l a t c h e s a r e screw type and t h e oven s i d e f ace of t h e - d o o r l i n i n g s have 5.1 c e n t i - meter (2 inch) t a p e r from t o p t o bottom. The top i s 5 .1 cent imeters (2 inches) t h i c k e r than t h e bottom t o minimize coke f a l l o u t onto t h e bench when t h e doors a r e removed. The ex tens ive use of c a s t i n g s on t h e b a t t e r y f ace and jambs of a S t i l l b a t t e r y can a l s o be seen i n t h i s door and jamb c ros s s ec t ion .

. The oven machinery is a l l 250 v o l t DC powered. The b a t t e r y is provided wi th one pusher machine, one door machine, one coke guide and two charging buggies. The charging buggies a r e u t i l i z e d f o r oven charging i n conjunct ion wi th two over- head chain conveyors. The charging buggies a r e equipped wi th automatic l i d l i f t e r s , mechanical gooseneck and s tandpipe c l eane r s and an oven coa l l e v e l sen- s i n g device. The pusher and door machines a r e both equipped wi th sc rape r b l ade type mechanical door and jamb c l eane r s . I n addi t ion , t h e pusher is equipped wi th an automatic l e v e l e r door opera tor and is designed f o r s i n g l e spo t door removal and replacement, oven pushing and oven l eve l ipg .

The coke catching, quenching and screening equipment is b a s i c a l l y of conven- t i o n a l design except t h a t t h e quench sump is provided wi th automatic breeze removal f a c i l i t i e s . he breeze removal f a c i l i t y is comprised of a buggy which moves along t h e top of t h e sump w a l l p u l l i n g a s c r a p e r along t h e sump bottom t o remove t h e breeze t o a d r a i n bas in .

The b a t t e r y top has four charging holes and a c o l l e c t o r main on both t h e pusher and coke s i d e s . The gas o f f t a k e s tandpipes have a 61 cent imeter (24 inch) i n s i d e l i n i n g diameter and t h e he igh t from t h e b a t t e r y top t o t h e s tand- p ipe cap is almost 4.3 meters (14' f t . ) . A combination f lu sh ing l i quor spray and steam a s p i r a t i o n nozz le is used i n t h e o f f t a k e elbow extension. The dampers a r e Pullman pan type.

(Figure 7) There a r e t h r e e s e p a r a t e c o l l e c t o r main s e c t i o n s on each s i d e of t h e b a t t e r y wi th 61 cent imeter (24 inch) diameter valved jumper l i n e s (5) between s e c t i o n s . The c o l l e c t o r mains measure 2.1 meters (81 inches) i n wid th and 2.0 meters (77 inches) i n he ight and a r e equipped wi th both spray type and bottom washing type f lu sh ing l i q u o r nozzles . The t h r e e gas o f f t a k e and cross- over mains a r e 1.8 meter (72 inch) diameter and each c o l l e c t o r main has i t s own back p re s su re c o n t r o l b u t t e r f l y va lve (1) and (2 ) . I n addi t ion , each crossover main has a s u c t i o n c o n t r o l b u t t e r f l y va lve (3 ) and a motor operated g a t e va lve ( 4 ) . The g a t e va lves can be remotely c o n t r o l l e d t o keep t h e crossover main suc- t i o n b u t t e r f l i e s i n c o n t r o l range.

r

Two sepa ra t e f l u sh ing l i q u o r processing f a c i l i t i e s , one f o r each c o l l e c t o r main, have been provided (F igure 8 ) . The design f e a t u r e s and flow of t he two systems a r e b a s i c a l l y t h e same. The major pieces of equipment a r e i d e n t i f i e d i n

I : Coke Side Collector Main Back Pressure Control Butterfly Valve 2: Pusher Side Collector Main Back Pressure Control Butterfly Valve 3: Suction Control Butterfly Valve 4: Motor Operated Gate Valve to Maintain Suction Butterfly Valves

in Control Range 5: 24" Jump Line Valve

I 7. B a t t e r y Gas o f f t a k e Cont ro l System.

- - - - @ ---- @ - L l Q W R 6 T A R . @ - FLOAT1 NG MATERIAL. 0 - FLOAT1 NG MATE RIAL TO

DISPOSAL. 0 - SETTLED MATERIAL TO

DISPOSAL . 0 - LIQUOR. @ - TAR TO STORAGE. Q-VALVED INTERODNNECTI~N.

W E A N T E RS

\

8. Ba t t e ry F lush ing Liquor System.

t h i s s i m p l i f i e d flow diagram. The l i q u o r and t a r flow from t h e c o l l e c t o r mains, a

by way of 1.2 meter (48 inch) diameter r e t u r n pipes, t o predecanter tanks . The predecanters a r e equipped wi th drags f o r removing both f l o a t i n g and s e t t l e d mater- i a l s . From t h e predecanters t h e l i q u o r and t a r flow t o f i n a l s t a g e decant ing tanks where t h e l i q u o r and t a r a r e separa ted and a d d i t i o n a l p i t c h sand i s allowed t o s e t t l e and be removed. From t h e s e decanters t h e l i q u o r is re turned t o t h e b a t t e r y and t h e t a r is pumped t o s t o r a g e tanks f o r shipment o r f u r t h e r processing. The f i n a l s t a g e decanters f o r t h e pusher s i d e main a r e t h e r ec t angu la r tank type commonly used i n t h e United S t a t e s , whi le those f o r t h e coke s i d e system a r e a cone bottom type. Both a r e designed t o a l low skimming of f l o a t i n g ma te r i a l s and t h e removal of s e t t l e d p i t c h sand. Also included i n both systems a r e foam water s epa ra to r tanks f o r f u r t h e r s epa ra t ion of t h e f l o a t i n g ma te r i a l s taken from both t h e predecanters and f i n a l s t a g e decanters .

Heat up of t h e b a t t e r y began on March 15, 1975, and gas was put i n t h e f l u e s on May 21, 1975. F lue temperatures were maintained a t approximately 1038OC (1900°F) u n t i l t h e charge d a t e of August 22. The b a t t e r y was held a t 24 hour coke f o r a t h r e e week per iod dur ing which i n i t i a l adjustments i n hea t ing were made. The coking t ime was then g radua l ly decreased t o 17% hours a t which time t h e average f l u e temperature was 1343OC (2450°F). Fu r the r decreases i n coking time have not been made because of r e s t r i c t i o n s i n va r ious b a t t e r y a u x i l i a r y equipment. However, our experience t o d a t e i n d i c a t e s t h a t lower coking times

I

can be obtained.

The b a t t e r y is operated i n such a manner t h a t every o the r oven is pushed and charged, t h a t is, ovens 1, 3, 5, 7, e t c . o r 2, 4, 6, 8, e t c . Such a system is necessary f o r cha in conveyor charging. This system w i l l be descr ibed l a t e r i n t h e paper.

Pushing ovens i n t h i s manner does have an advantage from a maintenance s tandpoint , i n t h a t i t reduces machine t r a v e l across t h e b a t t e r y and provides more time f o r maintenance on t h e va r ious sec t ions of t h e b a t t e r y , a s compared t o t ime a v a i l a b l e when us ing a Marquard pushing system. The pushing sequence has not caused any problems from a hea t ing s tandpoin t . ' However, a t extended coking times, such a s a 24 hour coke r a t e , charging ovens i n a s e c t i o n of c o l l e c t o r main is not accomplished f o r approximately 8 hours, t he re fo re , delays and c o n t r o l of back p re s su re become c r i t i c a l . This is t h e major reason f o r t h e 61 cent imeter (24 inch) valved jumper l i n e s between c o l l e c t o r main s e c t i o n s .

S ince s t a r t - u p , th$ b a t t e r y has operated f r e e of major problems. Also, oven carbon formation a t t h e f a s t e r coking times has not been a s e r i o u s problem t o da t e .

The No. 2 B a t t e r y Coal Prehea t ing o r "Precarbon" P lan t i s housed i n an open s t r u c t u r e which is approximately 28 meters (92 f t .) x 45.7 meters (150 f t .) x 76.2 meters (250 f t . ) h igh (Figure 9). The c h a r a c t e r i s t i c f e a t u r e of t h e "Pre- carbon Process" i s t h e combination of a two-stage v e r t i c a l column system f o r t h e thermal p r e t r e a t i n g of coking c o a l s and a cha in conveyor system arranged above t h e b a t t e r y f o r charging t h e coke ovens. The p r i n c i p a l process flow of t h e sys- tem is as follows :

The wet coa l , pu lver ized 90 - 95% minus .3175 cent imeters (1/8 inch) , is de l ive red t o t h e wet c o a l feed b i n (1) by means of a b e l t conveyor system and fed v i a a propor t ion ing device (2) and a c e n t r i f u g a l feeder (3) t o t h e f i r s t column ( 4 ) , known as t h e dry ing column.

When pass ing through t h e dry ing column, t h e c o a l i s d r i ed t o about 2% mois-

9. - Precarbon Process Flow Diagram.

t u r e and heated t o approximately 80°C (176°F) by hot c a r r i e r gases which were previous ly cooled from 550°C (1022°F) t o 280°C (536OF) i n t h e second s t a g e o r prehea t ing column (7 ) . A t t h e upper end of t h e dry ing column, t h e predr ied c o a l i s separa ted from t h e c a r r i e r gas i n a cyclone (5) and flows by g r a v i t y t o t h e base of t h e preheat ing column ( 7 ) , and is fed i n t o t h e column by means of a cen- t r i f u g a l feeder (6) . The predr ied c o a l i s thermal ly p re t r ea t ed with ho t c a r r i e r gases of approximately 550°C (1022"F), s o t h a t a t t h e column o u t l e t i t is f u l l y dry a t a temperature of approximately 200°C (392°F) .

Again a f t e r s epa ra t ion i n a cyclone (8) , t h e thermal ly p r e t r e a t e d coa l i s fed i n t o a mixer (9) where i t can be t r e a t e d wi th an a d d i t i v e t o reduce t h e car ry- over i n t o t h e c o l l e c t o r main when charging and/or t o ob ta in a des i red bulk dens i ty . The c o a l i s then t ranspor ted , v i a a cha in conveyor ( lo ) , t o a surge b in system (11) then t o a s e r i e s of weighing b ins (12) each having a volume of about one oven charge.

The c a r r i e r gas is produced i n a combustion chamber (15) by burning n a t u r a l gas wi th a i r . A i r f o r combustion is furnished by a combustion a i r blower (16). The c a r r i e r gas is f i r s t fed i n t o t h e preheat column (7) t o thermal ly p r e t r e a t t h e a l r eady predr ied coa l . The temperature of t h e gas is reduced from approxi- mately 550°C (1022°F) t o 280°C (536°F). Af t e r being separa ted from t h e preheated coa l , t h e c a r r i e r gas i s fed i n t o t h e dry ing column (4) where t h e temperature is again reduced, t h i s t ime from 280°C (536OF) t o 150°C (302°F). The c a r r i e r gas is then separa ted from t h e coa l i n a cyclone (5) and then flows t o t h e main blower (17). Af t e r passing through t h e blower, which provides t h e c i r c u l a t i o n of t h e c a r r i e r gas through t h e system, p a r t of t he c a r r i e r gas is recycled t o t h e com- bus t ion chamber. The remaining p a r t is f u r t h e r cleaned i n an e l e c t r o s t a t i c pre-

c i p i t a t o r (18) and r e l eased i n t o t h e atmosphere.

The fol lowing p r e s s u r e d i s t r i b u t i o n is obtained i n t h e system. The g r e a t e s t vacuum, approximately 1200 m i l l i m e t e r s (47.2 inches) water gauge, i s a t t h e out- le t of t h e dry ing column cyclones (5). A p re s su re l o s s of approximately 300 mi l l ime te r s (11.8 inches) water gauge occurs i n each s e t o f cyclones and i n both t h e dry ing and prehea t ing columns s o t h a t f i n a l l y t h e r e i s a p r e s s u r e o f f 0 mi l l ime te r s water gauge a t t h e e x i t of t h e combustion chamber.

The thermal p r e t r e a t i n g process is c o n t r o l l e d by t h r e e c o n t r o l systems and is f u l l y automatic. I n o rde r t o prevent an overhea t ing of t h e system and of t h e coa l , t h e temperature of t h e f l u e gas a t t h e e x i t of t h e prehea t ing column i s a r e f e rence va lue f o r t h e hea t input . For s a f e t y reasons t h i s v a l u e c o n t r o l s t h e combustion a i r input . I n a s e p a r a t e r a t i o c o n t r o l system, t h e a s soc i a t ed gas input - t o t h e combustion chamber i s con t ro l l ed , t ak ing i n t o cons ide ra t ion a pre- determined excess a i r va lue . The amount of c a r r i e r gas recycled t o t h e combus- t i o n chamber is c o n t r o l l e d by a t h i r d c o n t r o l system, s o t h a t t h e p r e s s u r e a t t h e i n l e t t o t h e prehea t column is never lower o r h ighe r than a p r e s e t p re s su re . The system thus au toma t i ca l ly compensates f o r v a r i a t i o n s i n t h e water conten t and throughput of t h e wet c o a l feed.

An e s s e n t i a l s a f e t y measurement i s t h e 02 content of t h e c a r r i e r gas. Dur- ing s t a r t - u p , c o a l is only added t o t h e system a f t e r t h e 02 content of t h e car - r i e r gas is l e s s than 8%. Normally t h e 02 content f a l l s t o l e s s than 4% a t t h e t ime t h e coa l i s added. I f t h e 8% 02 v a l u e i s exceeded during operat ion, t h e p l an t goes au tomat ica l ly i n t o a s a f e t y condi t ion . During these occasions t h e u n i t is shu t down and a n i t rogen purge of t h e e n t i r e system is e f f ec t ed .

I n event of a sudden emergency shutdown, t h e c o a l i n s i d e t h e columns drops i n t o water s e a l s (21) provided a t t h e base of t h e ind iv idua l columns.

Another s a f e t y f e a t u r e of t h e process is a water sp ray system a t t h e base of t h e drying column which is au toma t i ca l ly a c t i v a t e d i n event t h e temperature a t t h e i n l e t of t h e blower exceeds a p r e s e t h igh t e m p e r a t u r e , l i m i t . This f e a t u r e is e s s e n t i a l t o p r o t e c t t h e blower from damage due t o excessive hea t .

The preheated c o a l from t h e Precarbon P l a n t is conveyed t o t h e s t o r a g e b i n s ' (11) by means of cha in conveyors (10) . From t h e s t o r a g e b ins it i s fed t o measur- ing o r weigh b ins (12) v i a r o t a r y va lves . From t h e s e bins t h e preheated c o a l i s conveyed t o t h e oven t o be charged by means of cha in conveyors (13) and (14) arranged over t h e top of t h e b a t t e r y . The oven i s charged us ing chutes on a charging buggy (22) t o connect t h e cha in conveyors (14) t o t h e oven.

The charging sequence is a s fol lows: (Figure 10) By s e t t i n g f l o p ga tes i n t h e b i f u r c a t e d chu te on t h e charg ing buggy. Coal is f i r s t charged through t h e two inne r charging ho le s . The c o a l l e v e l i n s i d e t h e oven i s measured by means of l e v e l probes. When t h e des i r ed coa l l e v e l is obtained, t h e f l o p ga t e s a r e auto- m a t i c a l l y r epos i t i oned s o t h a t charging i s done through t h e two ou te r charging holes . When t h e l e v e l probes i n d i c a t e t h a t t h e requi red coa l l e v e l is reached, t h e cha in conveyors a r e stopped. No coa l l e v e l i n g i s r equ i r ed .

Contrary t o t h e d i r e c t i o n of t h e cha in conveyor t r a v e l , every o the r oven is charged going toward t h e measuring b ins - t h a t is , ovens 1, 3, 5, 7, e t c . o r 2, 4, 6, 8, e t c . Such a system i s necessary f o r cha in conveyor charging w i t h . t h e continuous feed procedure, because t h e conveyor des i gn d i c t a t e s t h a t a maximum of about 9 f e e t of coa l , t h e equiva len t of two ovens, can be c a r r i e d back on ' the t op s i d e of t h e chain conveyor.

SLIDE GATES

FL-R GATE FLOPPER GATE

10. S e c t i o n through ~ a t t e r y showing Precarbon Charging System.

(F igure 9) The system a l s o inc ludes a weighing b i n (12) . This a l lows t h e op t ion of charging t h e ovens batchwise. I f t h i s method is appl ied , t h e amount of coa l weighed i n t h e weigh b i n s ' i s given i n t o t h e empty cha in conveyor system, conveyed t o t h e oven t o be charged and t h e f u l l amount charged i n t o t h e oven. -

This charging procedure r e q u i r e s more t ime than t h e continuous feed system pre- v i o u s l y descr ibed .

The cha in conveyor and-charg ing buggy system can a l s o be used t o charge wet c o a l . There a r e , w e t coa l s t o r a g e b ins (19) and charging b ins (20) l oca t ed ad ja - cen t t o t h e preheated c o a l b in s . The s t o r a g e b ins a r e fed by a b e l t conveyor from t h e same c o a l tank which supp l i e s c o a l t o t h e Precarbon P l a n t .

(Figure 10) When charging wet coa l , c o a l is f i r s t charged through t h e two ou te r charging ho le s . The c o a l l e v e l i n s i d e t h e oven is measured by means of l e v e l probes. When t h e d e s i r e d c o a l l e v e l i s obta ined , t h e f l o p g a t e is automat- i c a l l y r epos i t i oned s o t h a t charging is cont inued through t h e two inne r charging holes u n t i l t h e l e v e l probes i n d i c a t e t h a t t h e des i r ed c o a l l e v e l is obtained. During l eve l ing , any a d d i t i o n a l c o a l requi red is charged through one of t h e i nne r charging ho le s only and t h e amount i s l im i t ed by a p r e s e t t imer .

A t t h e t ime t h i s paper was prepared, p r e s t a r t u p debugging of t h e Precarbon P l a n t was i n progress . No oven had been charged wi th prehea ted c o a l b u t s e v e r a l hundred tonssof c o a l had been run through t h e Precarbon P l a n t us ing an oven by- pass system. We had, however, s u c c e s s f u l l y charged ovens w i th wet c o a l us ing t h e cha in conveyor and charging buggy system.

I n a d d i t i o n t o t h e No. 2 Ba t t e ry and Precarbon P l a n t descr ibed h e r e today, we a l s o have a No. 3 B a t t e r y a n d p r e c a r b o n P l a n t under cons t ruc t ion . These f a c i l - i t i e s ' a r e scheduled t o be placed i n ope ra t i on sometime i n 1976. From t h e looks - of t h ings t h e r e is no doubt t h e next s e v e r a l years w i l l be an i n t e r e s t i n g cha l - lenge f o r t hose of us working a t t h e Gary Works Coke P l a n t .

COMMENTS ON PAPER OUTLINING

DESIGN, CONSTRUCTION AND START-UP OF

UNITED STATES STEEL'S NO. 2 COKE BATTERY AT GARY WORKS

Klaus Urbye

Chief Commissioning Engineer

Firma Car l S t i l l

Recklinghausen, West- Germany

I t h i n k t h a t t h e paper, read by M r . McHenry, explained i n a very good way t h e design, cons t ruc t ion and s t a r t - u p - o f t h e No. 2 coke b a t t e r y a t United S t a t e s S t e e l ' s Gary Works. This paper descr ibed t h e design f e a t u r e s of t h e S t i l l High- Capacity Coke Ovens and t h e p r i n c i p l e s of t h e hea t ing system and a l s o t h e design and ope ra t ion of t h e "Precarbon Process" and t h e f lu sh ing l i q u o r process ing f a c i l i t i e s .

I

Adding a commentary is done only because, i n t h e t ime between prepar ing t h i s paper and t h e reading of today, f u r t h e r experience w i t h t h e b a t t e r y has been gained and a number of ovens have been charged wi th preheated coa l .

During opera t ion of t h e b a t t e r y i t was proved r i g h t t h a t a 3%" t a p e r of t h i s If

oven requi red 17 hea t ing f l u e s f o r t h e pusher s i d e and 14 hea t ing f l u e s f o r t h e 1

coke s i d e . Thus, it i s p o s s i b l e t o provide both s i d e s w i th t h e same hea t ing gas flow snd t h e same amount of a i r . A s a r e s u l t , bo th s i d e s have t h e same waste gas flow and, t he re fo re , an i d e a l ba lance of hea t d i s t r i b u t i o n . The temperature i nc rease from pusher s i d e t o coke s i d e is 80°C (150°F). The temperature drop t o t h e end hea t ing f l u e s is 80 t o 100°C (150 t o 180°F). The temperature of t h e end hea t ing f l u e s , i n any case, can be ad jus t ed i n a wide range because t h e end heat- ing f l u e s have a d d i t i o n a l c o n t r o l f a c i l i t i e s . There a r e two a d d i t i o n a l channels which run from t h e base of t h e end h e a t i n g f l u e s t o t h e regenera tor chambers. The i r c ros s s e c t i o n s can b e ad jus t ed by means of s l i d e b r i cks . The s l i d e b r i c k s a r e e a s i l y a c c e s s i b l e from t h e bench g a l l e r y top. By t h i s means t h e amount of I

ai r t o t h e end hea t ing f l u e s f o r hea t ing wi th coke gas and t h e amount of a i r and gas f o r hea t ing wi th l e a n gas can be ad jus t ed independent ly of t h e o the r hea t ing . I

These channels a r e a l s o ve ry important f o r t h e hea t ing up of t h e b a t t e r y s i n c e they give, when f u l l y open, almost double t h e c ros s s e c t i o n f o r t h e waste gases

I

t o pass than t h e normal hea t ing f l u e . By t h i s means t h e end hea t ing f l u e s a r e . , heated v e r y i n t e n s e l y dur ing hea t ing up. Thanks t o t h i s unique f ea tu re , t h e r e were no heatup damages t o t h e chamber wa l l s seen a t a l l i n t h e S t i l l High Capa- c i t y Ovens a t Gary.

The No. 2 b a t t e r y was, up t o now, heated only wi th coke gas. The gas - a i r r a t i o is ad jus ted i n such a way t h a t t h e waste gases have an 02 content between 4 and 5%. With t h i s adjustment t h e v e r t i c a l temperature d i s t r i b u t i o n guarantees

t h a t , on t h e one s i d e , t h e top p a r t i s we l l cooked coke while, on t h e o the r s i d e , t h e formation of annoying carbon i n t he chamber roof is prevented. The hea t ing system shows t h e fol lowing p re s su re p r o f i l e :

Waste gas v a l v e s on t h e upburning s i d e -6 MMWS Above t h e regenera tor , upburning s i d e - 3 MMWS I n t h e hea t ing f lues , b a t t e r y top, downgoing +1 t o 2 MMWS - Above t h e regenera tor , downgoing -8.5 &S Waste gas va lves , downgoing -15 MMWS Cont ro l led s t a c k draught -20 MMWS Waste gas temperature 270" C

The f i g u r e s a r e measured a t a coking time of 17.5 hours. The h e a t i n g f l u e temperature i s about 1310°C (2390°F). The c o l l e c t o r main p re s su re is adjus ted a t +10 MMWS. A t t h i s c o l l e c t o r main p re s su re a l l chamber openings show, i n gen-

\ e r a l , a good t i g h t n e s s ; e s p e c i a l l y t h e oven doors developed by U. S. S t e e l showed an exce l l en t t i gh tnes s .

As a l r eady s t a t e d , a cons iderable number of ovens have been charged wi th preheated coa l . There were s e v e r a l t e s t s i n which only two o r t h r e e ovens were charged and one continuous t e s t of over 48 hours. I n t h i s two day t e s t ovens 1 t o 29 were charged with wet c o a l and ovens 30 t o 57 wi th d ry coa l . For t h i s t e s t 66 ovens were-charged wi th d ry coa l . The coking time f o r t h e d r y charges was 14 hours, f o r t h e wet charges 20 hours, a t a hea t ing f l u e temperature of about 1290°C (2359°F). Addit ives which should decrease t h e carryover i n t o t h e c o l l e c t o r main were no t used during these t e s t s .

The fol lowing recogni t ions and r e s u l t s were obtained dur ing t h e s e t e s t s :

The bulk d e n s i t y of preheated c o a l charges was cons iderably h igher than t h a t of wet coa l charges.

I n t h e s i n g l e t e s t s t h e coking t ime was decreased t o 12 hours a t a hea t ing f l u e temperature of 1320°C (2408°F).

The charging was done by u t i l i z i n g Number 2 and 3 charging holes . However, charging was a l s o done using only one charging ho le - Number 2 o r 3 . I n each c a s e a good charging p r o f i l e i n t h e oven chamber was obtained. This has t o be checked when a d d i t i v e s a r e mixed wi th t h e coa l . The q u a l i t y of t h e coke was improved a s expected.

During t h e s t a r t up of t h e Precarbon P lan t , r e p r e s e n t a t i v e s of Bergbau- Forschung, C a r l S t i l l and Gary Operations worked c l o s e l y toge the r t o c o r r e c t t h e number of minor d i f f i c u l t i e s t h a t a rose . The problems encountered wi th t h e charging system appear t o be solved and t h e p rehea te r r e v i s i o n s a r e a t a p o i n t t h a t continuous opera t ion can begin i n t h e ve ry near fu tu re .

The f lu sh ing l i q u o r process ing f a c i l i t i e s have been operated s o f a r without major problems. The water conten t i n t h e t a r of t h e S t i l l decanters i s an average 2%; t h e content of s o l i d s is 7 t o 8%.

A t t h i s p o i n t I would l i k e t o express t h e s i n c e r e thanks of Firma Car l S t i l l t o U. S. S t e e l f o r t h e exce l l en t cooperat ion dur ing design, cons t ruc t ion and s t a r t up of No. 2 B a t t e r y i n Gary. I p a r t i c u l a r l y would l i k e t o thank M r . McHenry and M r . Land f o r t h e cooperat ion t h a t made it always a p l easu re t o work wi th them and t h e i r crews even during per iods of ope ra t iona l d i f f i c u l t i e s .