AMMONIA CONVERTERAMMONIA CONVERTER

Muhammad AdnanMuhammad Adnan

R-501

Uneven Bed TemperaturesUneven Bed Temperatures

OBJECTIVEOBJECTIVE

[[ Diagnostics of Ammonia Converter uneven catalyst Diagnostics of Ammonia Converter uneven catalyst

bed temperatures bed temperatures ]]

Introduction / LayoutIntroduction / Layout

Flow pattern of Ammonia ConverterFlow pattern of Ammonia Converter

Problem Identification Problem Identification

Possible Causes & AnalysisPossible Causes & Analysis

ConclusionConclusion

CONTENTSCONTENTS

INTRODUCTION

3 Bed Iron based catalyst

NN22+3H+3H2 2 2NH2NH33 + heat + heat

Operating Temperature

360°C – 380°C

Converter capacity

1250 MeT/day

Operating Pressure

260 Kg/cm²

Radial Flow Pattern Axial-Radial Flow Pattern

Reactor Flow Patterns

05-HIC-1001V05-HIC-1002V

05-TRC-3V

05-HIC-1V 05-HIC-1V

Temperature monitoring of Catalyst Temperature monitoring of Catalyst BedBed

Thermocouples installed in four thermo wells.Thermocouples installed in four thermo wells.

Two thermo wells containing TI’S.Two thermo wells containing TI’S.

Two thermo wells containing TR’S.Two thermo wells containing TR’S. Each TI & TR has a spare.Each TI & TR has a spare.

Each TI & TR have equal length.Each TI & TR have equal length.

Bundle T1 Bundle T4

Bundle T2 Bundle T3

Temperature Monitoring of Ammonia Converter Catalyst Bed

05-TI-01

05-TI-02

05-TR-01

05-TR-02

05-TI-0305-TR-03

05-TI-0405-TR-04

05-TI-05 05-TR-05

05-TI-06

05-TI-07

05-TI-08

05-TI-09

05-TR-06

05-TR-07

05-TR-08

05-TR-09

99

Failures of Valve Bodies of P101A/B/C

320

340

360

380

400

420

440

460

480

500

520

540

Tem

pera

ture

1st bedInlet TI

1st BedInlet TR

1st BedOutlet TI

1st BedOutlet TR

2nd BedInlet TI

2nd BedInlet TR

2nd BedOutlet TI

2nd BedOutlet TR

3rd BedInlet TI

3rd BedInlet TR

Thermocouple

Temperature Profile During Normal Condition

Catalyst Bed Temperature Profile during Start-UpCatalyst Bed Temperature Profile during Start-Up

Ammonia Converter 1st Bed Temperature Profile

0

100

200

300

400

500

600

Time

1420

1500

1530

1600

1630

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1730

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1830

Time

Tem

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atu

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TI-1 TR-1 T1-2 TR-2

`

Catalyst Bed Temperature Profile during Start-UpCatalyst Bed Temperature Profile during Start-Up

Ammonia Converter 2nd Bed Temperature Profile

0100200300400500600

Time

Te

mp

era

ture

T1-03 TR-03 T1-04 TR-04

1212

Failures of Valve Bodies of P101A/B/C

0

50

100

150

200

250

300

350

400

Tem

per

atu

re

1st BedInlet TI

1st bedInlet TR

1st bedOutlet TI

1st BedOutlet TR

2nd BedInlet TI

2nd BedInlet TR

2nd BedOutlet TI

2nd BedOutlet TR

3rd bedInlet TI

3rd BedInlet TR

Thermocouple

Temperature Profile During Shutdown

Temperature Profile StudyTemperature Profile Study

Uneven heating of catalyst bed which increases Uneven heating of catalyst bed which increases

especially during high flow and high especially during high flow and high

loop pressure conditions.loop pressure conditions.

Possible CausesPossible Causes

TI’s & TR’s indicating false readingTI’s & TR’s indicating false reading

Synthesis Loop Pressure is not as per designSynthesis Loop Pressure is not as per design

NHNH33 Concentration at reactor inlet is not as per design Concentration at reactor inlet is not as per design

Non Uniform Flow DistributionNon Uniform Flow Distribution

TI’S & TR’S are indicating TI’S & TR’S are indicating

false reading?false reading?

Result of thermocouples studyResult of thermocouples study

Synthesis loop pressure is Synthesis loop pressure is

not as per design?not as per design?

Result of loop pressure studyResult of loop pressure study

NHNH33 Concentration at Concentration at

Converter Inlet is not as per Converter Inlet is not as per

designdesign??

Result of ammonia concentration studyResult of ammonia concentration study

Non uniform distribution of Non uniform distribution of

flow?flow?

Result of non uniform flow studyResult of non uniform flow study

There is non uniform flow distribution across the bed length.There is non uniform flow distribution across the bed length.

the non uniform flow distribution is the basic cause of our the non uniform flow distribution is the basic cause of our problem. problem.

This is basic cause of difference in the temperature at TI & TR This is basic cause of difference in the temperature at TI & TR

ConclusionConclusion

The cause of our problem is the non uniform flow cause of our problem is the non uniform flow

distribution on the catalyst bed which is mainly due of distribution on the catalyst bed which is mainly due of

Improper degree of packing Improper degree of packing

Channeling in the catalyst bedChanneling in the catalyst bed

Quench flow is not properly mixingQuench flow is not properly mixing

Q & A

Problem IdentificationProblem Identification

uneven catalyst bed temperature can leads to following uneven catalyst bed temperature can leads to following problems if not identify its proper reason problems if not identify its proper reason

Efficiency lossEfficiency loss

Loss of productionLoss of production Catalyst damageCatalyst damage

Loss of equipmentLoss of equipment

Misguide us on controlling catalyst bed temperatures.Misguide us on controlling catalyst bed temperatures.

Converter providerConverter provider Ammonia casale Ammonia casale

Capacity (MET/DAY)Capacity (MET/DAY) 12501250

CatalystCatalyst Magnetite catalyst activated with Magnetite catalyst activated with KK22O,CaO,AlO,CaO,Al22OO33,MgO,MgO

No. of catalyst bedNo. of catalyst bed 33

Equivalent particle size (mm)Equivalent particle size (mm) 1.381.38

Catalyst volume (m3)Catalyst volume (m3) 32.90 32.90

Form of catalystForm of catalyst Irregular shape Irregular shape

Flow pattern Flow pattern Axial radial typeAxial radial type

heat exchangers includedheat exchangers included 22ndnd bed outlet bed outlet

Bottom exchangerBottom exchanger

Total converter pressure drop Total converter pressure drop 2.362.36

Temperature controllingTemperature controlling

05- TRC-3V (for controlling of 1st bed inlet temperature)05- TRC-3V (for controlling of 1st bed inlet temperature)

05-HIC-1001V (for controlling of 2nd bed inlet temperature)05-HIC-1001V (for controlling of 2nd bed inlet temperature)

05-HIC-1002V (for controlling of 3rd bed inlet temperature)05-HIC-1002V (for controlling of 3rd bed inlet temperature)

BED 1

BED 2

BED 3

HIC-1001

HIC-1002

Bottom Exchange

HIC-1

05-TRC-3

F-501

HIC-3V

E-501A/B

E-502

BLUE LINE = COLD GASYELLOW LINE = MEDIUM TEMP. GASRED LINE = HOT GAS

AMMONIA CONVERTER TEMPEARATURE CONTORLING BLOCK DIAGRAME

TITI’’S & TRS & TR’’S are indicating false S are indicating false readingreading??

Each TI & TR present on same bed at 180 angle.Each TI & TR present on same bed at 180 angle.

Each TI & TR have spare thermocouple available.Each TI & TR have spare thermocouple available.

Each TI & TR, their spare thermocouple shows same Each TI & TR, their spare thermocouple shows same reading.reading.

TI and TR present on the same catalyst bed shows TI and TR present on the same catalyst bed shows

almost same reading during shutdown condition.almost same reading during shutdown condition.

Synthesis loop pressure is not as per Synthesis loop pressure is not as per design?design?

Design pressure is 225 kg/cm2 Design pressure is 225 kg/cm2 working pressure is 257 kg/cm2 .working pressure is 257 kg/cm2 .

There can be following causes of increasing loop pressure.There can be following causes of increasing loop pressure.

I.I. decrease in catalyst activitydecrease in catalyst activity

II.II. changing of Hchanging of H22/N/N22 ratio away from optimum ratio away from optimum

III.III. increase in make up flow ratesincrease in make up flow rates

IV.IV. decreasing the circulation rate causing increase in inserts leveldecreasing the circulation rate causing increase in inserts level

NH3 concentration at converter inlet is not as per NH3 concentration at converter inlet is not as per designdesign??

Ammonia concentration is 2.85% Ammonia concentration is 2.85% Design figure of about 4% Ammonia.Design figure of about 4% Ammonia.

Ammonia in reactor feed gas plays a role in controlling Ammonia in reactor feed gas plays a role in controlling the temperature.the temperature.

Ammonia concentration at the ammonia converter inlet is Ammonia concentration at the ammonia converter inlet is less then the design figure.less then the design figure.

This will cause higher rate of reaction means higher This will cause higher rate of reaction means higher temperaturetemperature..

Result of ammonia concentration studyResult of ammonia concentration study

This is not a cause of this problem because we have run This is not a cause of this problem because we have run plant by changing the ammonia concentration at reactor plant by changing the ammonia concentration at reactor inlet but the problem was remain unchanged.inlet but the problem was remain unchanged.

Temperature changes should be same throughout the Temperature changes should be same throughout the catalyst bed.catalyst bed.

As ammonia concentration changing at inlet cause the As ammonia concentration changing at inlet cause the temperature changing throughout the bed so this is not the temperature changing throughout the bed so this is not the cause of our problem.cause of our problem.

Non uniform distribution of flow?Non uniform distribution of flow?

The non uniform distribution of flow means the flow of fluid is not The non uniform distribution of flow means the flow of fluid is not equally divided throughout the bed length.equally divided throughout the bed length.

The uneven flow of gas can leads to the problem of uneven The uneven flow of gas can leads to the problem of uneven temperature across the bed.temperature across the bed.

This can leads to the problem of uneven temperature profile This can leads to the problem of uneven temperature profile because the reign where the flow of gas is higher shows a higher because the reign where the flow of gas is higher shows a higher temperature than other low flow reign.temperature than other low flow reign.

the thermocouple present on the side of higher flow reign shows the thermocouple present on the side of higher flow reign shows a higher temperature then the thermocouple present on the low a higher temperature then the thermocouple present on the low flow reign.flow reign.

Temperature profile of catalyst bed during shutdownTemperature profile of catalyst bed during shutdown

This trend showing that temperature at respective TI’s & TR’S is almost same This trend showing that temperature at respective TI’s & TR’S is almost same

Temperature profile during shutdown

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TI-01 TR-01 TI-02 TR-02 TI-03 TR-03 TI-04 TR-04 TI-06 TR-06

thermocouple

Tem

prat

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100

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400

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600

TI-01

TR-01

T1-02

TR-02

TI-03

TR-03

TI-04

TR-04

T1-06

TR-06

Temperature profile of catalyst bed during normal operationTemperature profile of catalyst bed during normal operation