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APPLICATION REPORT

2721 / 11 / 0 6 • 5 / 2 011

Delayed coking - coke drums

COKEDRUM 1

COKEDRUM 2

FURNACE

FRACTIONATOR

BLOWDOWNDRUM

DECOKINGWATER

TANK

4-way switchvalve

Drain Drain

Fresh feed

Overhead gases

Bottom tofurnace

Coke drumoverhead vapor

Fuel to burners

Recycle

Coker naphta

Light gas oil

Heavy gas oil

Bypass

tofractionator

Process overviewDd c d f cvt

v f hv d t vb

tptt f. Fxbt pt d

-t -qpt ct

ptt d tt. Ct p-

tion is important for protable delayed coking. The

t c pc tpc pd t th

ct – fc d fctt, c

d d c hd d th cd bwdw

areas. The exact conguration will vary upon ren-

ery’s specic design strategy and existing process-

ing capabilities. The most common feedstock is

vc d; hwv, th hv t

d, ch vb t, , t

d d ptch.

The fresh feed combined with distillate recycle

htd th fd pht xch t t

about 280 – 320 °C. The prehated residue is sent

t th btt f th fctt bf ht

the furnace to about 500 °C. High-pressure steam

b fdwt jctd t th fc c

f pt vct d dc t t ct

the coke formation in the tubes. The coke drums

dwt th fc pvd ct t f

sufcient coking reaction and collection of solid

coke formed. While one coke drum is being lled

for a xed cycle time, typically 16 to 18 hours, the

th c d d th c, ctt,

and drum preparation steps. The closed blowdown

t xz hdcb d wt cv-

, pvd c f th c d d -

z pt d pt.

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2721/11/06 DelayeD Coking - Coke Drums

2 APPLICATION REPORT 5/11

Delayed coking challengesThe target of delayed coking process is to start

cracking the heavy feedstock in coking furnace

and complete the cracking and coking in the

coke drums downstream the furnace. Coking in

other process equipment, furnace, fractionator

and coke drum overhead line cannot be com-

pletely avoided. This must be taken into ac-

count throughout the delayed coking process

when selecting valves for control, on-off and

ESD-applications.

Health, Safety, Environment – Vv

p bth vt d ft d

to risk of re, toxicity and volatility of gases. Emer -

c htdw d /ff vv t b b

t pf th ct pc qpt

f.

Top-class products at maximum yield – Thet c f c pdct d hh qt. it

is important that the process is stable, exible and

d ct. Pp ct vv pfc

fc d fctt pv th ccc

f thhpt ct d dv ffct t th

pt pfc d th dwt p-

c.

Maintenance costs - Ctc vv c d

wtch, t, d d vhd ct

p xt ptt ccf c

d d v pc pfc. Ppf vv th pc t b vcd

bc th w hv dct pct th f-

ciency of the process.

Plant run-time – Reneries are looking for longer

pt -t c dwt pdct

d b ct cd t-

nance costs. This requires reliable equipment and

pc ct.

Metso solutionsWe are all tuned up to answer these challenges

through our refining application experience

and product offering for control, safety and

automated on/off duty that ensure high valve

performance in delayed coking plants. Our ap-

plication specific automated coke drum valves

are designed for efficient and reliable process

operation.

Safety - mt th c -

c htdw vv pp wh h th xp-

c d wd t cb tc wth

most reliable valves and actuators. Technology

ct t t pt d ht

re safe design ensure that latest emission and re

ft tdd c b ppd. rb vv

with rst intelligent, SIL3 approved safety valve

ct d pt t tt t n

ValvGuardTM will ensure that plant emergencyhtdw vv w w pf pp wh

dd.

Efficiency - Throughput losses due to heavy

d tc d p ct pfc w

b vdd wth tt ct vv. Fw

thh th pc t b chd th

need arises with rangeability of 150:1 and further

wth f b b vv. o dvcd tt

dt vv ct f ct, -ff d esD

ppct hh pt ccc d

ft p. Cct vv ct d zwth npf-p w c th bt

vv pfc d pc ct.

Availability - sp t d, fc-t-

fc d, d b vc tw d

vt t w hp t ptz

tc ctvt. rt vv hv

b vc f v wtht q-

tc d hw f .

The proven performance of Metso valves with long

t t t tht d ht-ff cpb-

t th d t f ct, -ff

d ctc c d ppct.

Reliability - Vv pfc td dt c-

ctd b t vv ct d d

by Metso FieldCare, open FDT/DTM technology

based conguration and condition monitoring soft-

w, t pb t pdct d pd t

tc qt d dc chd-

uled downtime. This gives full transparency to the

vv pfc pc ct.

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DelayeD Coking - Coke Drums 2721/11/06

APPLICATION REPORT 5 /11 3

Coke drum applications

sc th tpc 12 ctc vv vvd

th c d pt, vv pfc p

- th pt t z pt

xp d t c pdct d qp-

t. effctv pt f c d c

pdctvt d xtd pc p-t. Wth

hcd t p t, ct t-

t hv xhbtd xtdd vc f.

sv tc f pt wth mt

dd c vv v ptt ct v f

USD 540.000 in maintenance costs alone.

4-way switching valve (1)

Challenge - This is a very challenging application

due to the variety of uids and service parameters.

Vv t hd hh p, hv d-

t vtd tpt. a th c fd

(vp-qd cbt) xt th c ht t

p t hv c. rdc t th ht v ht d t z c cc-

t, d t v th cc, th ht.

The feed then passes through the 4-way switching

vv d t th ctv c d. ath ctc

function of the 4-way switching valve is to keep the

fd v th

t d a, d

B, t bp.

oc htd

bv th th

cc tp-

t, vv,pp, v

pump that the uid

wd t tp

in will ll with solid

c, d t

.

Metso solution – With over 25 year of experience,

the series Y4, 4-way switching valve, is another

xp f mt’ ctt t tchc

dhp thh d xcc.

Benefit – Maximum process efciency is achieved

by fully automated Metso 4-way switching. The

tt C-m bd cpb f pvd-

vc f pc cdt f hv

d. o wdd bd ctct wth

t t p t th d f x-

pv d dd wd ht ttt tht

cvt p d.

Metso Service Centers can efciently refurbish

these 4-way switching valves, increasing return on

vtt d dc pd tc

ct. o ct hv xpcd t-

c f pt f 7 wth v -

tenance cost savings of USD 140.000 for each

4-way switching valve.

Coke drum isolation valves (2)

Challenge - The coke drum isolation valves are re-

quired to ow and isolate in both directions. When

th c d ctv, th p f vv p

t dt th ch. Wh th d bc

ctv f dc d c, th t

valve must allow for the ow of steam, water and

coke in the reverse ow direction. This uid is the

t f th dc pc d bv

t. Fd th vd f th t

thh th c d d vv. at th

t, th cd c d t vv t

isolate to prevent the back-ow of decoking slurry

to the 4-way switching valve.

Metso solution – F c d t th -d d ft f th mt mBV f

b t-td b vv, t th p

ppct chc. Wth mt’ dvcd cc-

t th t cpt f ctc vv c

b cctd v cct.

Figure 2. Metso MBV coke drum isolation valve

Benefit – There is no room for errors when han-

d th hv d tht pcd th

dd c. if th pdct wd t cp

t th b/t t b , th

vv w jt z p t t . nt

d th z p, bt t t pb t t

them clean again. Take it from a valve rebuilding

xpt wh wd th pjct, “it’ th th-

t tt t ’ v f.” s

tht’ wh p p ch ptt pt f

ctc c vv’ d.

o ct hv xpcd tc

f pt f 7 wth v t-

nance cost savings of $400.000 for each pair of

c d.

Figure 1. Metso 4-way switching valvefor a customer in the USA

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2721/11/06 DelayeD Coking - Coke Drums

4 APPLICATION REPORT 5/11

Overhead vapor line valves (3)

Challenge - Vp t f th ctv c d

d pt. it p thh bth

vhd vp vv d th vhd vp

ct vv t w t th fctt.

D dc, th vhd vp vv

ct t th w ctv d t t t

upstream side. This prevents the steam, water and

c tht t f th dc pc f

t th vhd vp d ctt

th pdct t f th th ctv c d.

st, th cd vv f th p t

isolate on its downstream side. This prevents prod-

ct t f th ctv d f b wtd

by mixing with the decoking efuent.

Metso solution – mt mBV, f-b t-

-td b vv, t th p ppc-

t chc f vhd vp vc. mt ff f ctt d ttt

to suit specic design requirements.

Figure 3. Metso 24” MBV at customer’s Coker plant

Benefit – kw tht t cvt

cc, th ctt th mt vv

zd t tt th vv qc f f p t

full close. Typically, all of the stroking times on any

size of 2-way valve are under one minute. This

tht t f t w b d

t p th cct f d d th

b t bt . mt pc

calculates steam ow into all purge ports. We rec-

ommend orices at each purge port that control a

constant steam ow rate to each purged area thus

z th tt t qd. l t

means more prot.

Coke drum drain valves (4)

Challenge - When the coke drum in service is lled

to a specic level, the fresh charge from the heater

is switched to the empty coke drum. The full drum

td, td t v hdcb vp

and cooled by lling with water.

The combination of solid coke, water and steam

referred to as decoking efuent is removed from

the system through the coke drum drain valve. The

uid pressure and temperature can vary heavily de-

pd th c d pt pt.

Metso solution –The rugged full-bore, abrasion

resistant X-MBV ball valve provides the rener with

p ppct pfc. mt fc-

t f f b vv tht p t th -

nicant and varied challenges of the delayed coker vc, w ctt d ttt t

suit specic design requirements.

Benefit – This again is a very demanding applica-

t d t th bv t f th dc f-

uent. The full bore CR-Mo body provides excellent

b tc t w tc

d btt bt.

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DelayeD Coking - Coke Drums 2721/11/06

APPLICATION REPORT 5 /11 5

Overhead Vapor Line Back Pressure Control

Valve (5)

Challenge – Demand for better process efciency

q ht c d cc t. Ft d

w-p pd pbt wh dc

th v cc t. a cvt thd t

hd bc p wth th cbd vhd

vapor line back pressure control valve. This re-

q d ctbt f th vv b.

Metso solution – Metso’s special buttery valve,

wtht t , th t f bt ct

pfc.

Figure 4. Metso Neldisc special butterfly valve

Benefit – sf w vt, w ftv

, d wth v-dd pc d

t p cct. it pvt th tv

f txc vp thh th pc t th t-ph. Wth d th vv v

d t vd d vpzt tht

major safety benet.

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The information provided in this bulletin is advisory in nature, and is intended as a guideline only.

For specic circumstances and more detailed information, please consult with your local automation expert at Metso.

Metso Automation Inc.

Europe, Vanha Porvoontie 229, P.O. Box 304, FI-01301 VANTAA, Finland.Tel. +358 20 483 150. Fax +358 20 483 151

North America, 44 Bowditch Drive, P.O. Box 8044, Shrewsbury, MA 01545, USA.Tel. +1 508 852 0200. Fax +1 508 852 8172

South America, Av. Independéncia, 2500- Iporanga, 18087-101, Sorocaba-São PauloBrazil. Tel. +55 15 2102 9700. Fax +55 15 2102 9748/49

Asia Pacific, 20 Kallang Avenue, Lobby B, #06-00, PICO Creative Centre, Singapore 339411, Singapore.Tel. +65 6511 1011. Fax +65 6250 0830

China, 19/F, the Exchange Beijing, No. 118, Jianguo Lu Yi, Chaoyang Dist, 100022 Beijing, China.Tel. +86-10-6566-6600. Fax +86-10-6566-2575

Middle East, Roundabout 8, Unit AB-07, P.O. Box 17175, Jebel Ali Freezone, Dubai,United Arab Emirates. Tel. +971 4 883 6974. Fax +971 4 883 6836

www.metso.com/valves

APPLICATION REPORT

2721_11_06en

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