Optimizing the Installation and Operation of a New 3-Bed

2011 [313] AMMONIA TECHNICAL MANUAL

Optimizing the Installation and Operation of a New 3-Bed Ammonia Synthesis Converter Basket

After serving for about 18 years, Haldor Topsoe design S-200 basket was replaced in 2009 with a new

S-300 basket. The changeout was completed within the scheduled time and proved to be a successful

project as both the production and efficiency were appreciably higher than the design figures.

In 1992, in the high pressure Synthesis loop of a 1,000 MTPD ammonia plant of Haldor Topsoe design

a new S-200 basket was installed to upgrade the design capacity of the unit to 1,220 MTPD. By year

2008, the production demand from the converter had increased to more than 1350 MTPD thus

warranting a change of catalyst and better design. Catalyst activity had decreased and was causing a

high loop pressure i.e. 269 kg/cm2g (3826 psig). Meticulous planning and execution of the project,

including catalyst services in an inert atmosphere, resulted in significant lesser time to execute the

change-out. This paper describes various steps taken to minimize the change-out time without

sacrificing the safety of personnel and equipment. Commissioning was also a unique experience

starting from catalyst reduction till the converter optimization with the help of simulation tools. New S-

300 was able to produce 1,492 MTPD ammonia apart from significant reduction in the energy

consumption.

Ather Iqbal and Noor-ul-Hassan

Fauji Fertilizer Company Ltd., Goth Machhi, Pakistan

Introduction

auji Fertilizer Company (FFC) is the

largest urea manufacturer in Pakistan,

operating three ammonia-urea plants; two

at Goth Machhi and one at Mirpur Mathelo. The

first plant (Plant-I) was commissioned in 1982 at

Goth Machhi with design capacities of 1,000 and

1,725 metric tonnes ammonia and urea per day,

respectively. The ammonia plant employed

conventional Haldor Topsoe design, while the

urea plant was based on Saipem (Snamprogetti)

ammonia stripping technology. The plant was

successfully revamped to 122.5 % of design

capacity in 1992 after installing a new 2 bed

basket.

Plant-II was commissioned in March 1993 with

design capacities of 1,100 and 1,925 metric

tonnes ammonia and urea per day, respectively.

The ammonia plant was based on Haldor Topsoe

low energy process, incorporating a Medium

Temperature Shift Reactor.

Plant-III at Mirpur Mathelo was acquired in

2002 and was similar in design to Plant-I; design

capacities were 1,000 and 1,740 metric tonnes

ammonia and urea per day, respectively. This

plant was also successfully revamped to 125 %

of design capacity in 2008.

F

3132011 AMMONIA TECHNICAL MANUAL


Ammonia-I Plant

The ammonia plant being discussed in this paper

is the one at Goth Machhi (also designated as

Plant-I).

Process Description

Ammonia-I plant is a conventional Haldor

Topsoe design of the late seventies, featuring

high steam to carbon ratio (3.75), hot potassium

carbonate system for carbon dioxide removal and

ammonia synthesis loop operating at high

pressure.

It consisted of desulfurization, conventional

reforming and high and low temperature shift

conversion sections in the front-end. The carbon

dioxide removal section utilizes the Benfield

technology from UOP, which was up-rated to

Benfield Lo-Heat process in 2004, followed by a

methanation reactor.

The synthesis loop operates at a very high

pressure of 267 kg/cm2g (3798 psig). All the

major compressors i.e., process air, synthesis gas

and ammonia refrigeration are centrifugal

compressors driven by steam turbines.

A simplified process flow diagram of the

Ammonia-I plant is presented in Figure 1.

Figure 1: Ammonia-I Process Flow Diagram

Operational History

The plant started production in 1982 and had the

distinction of achieving the design capacity in

the first year of its operation. The ammonia

production from the plant was increased to 115%

of the original design by 1990 with small

modifications.

Ammonia Converter

The ammonia converter internals consisted of an

Haldor Topsoe designed S-200 basket installed

in 1991 as a part of the plant revamp, replacing

the original S-100 converter basket.

The catalyst loaded in 1991 required replacement

owing to deteriorated performance with respect

to lower conversion efficiency and higher

approach to equilibrium after 18 years of

satisfactory performance. In order to gain

maximum benefit of plant outage owing to

catalyst change-out, replacement of S-200 with

S-300 was also synchronized.

Study for Three-Bed Basket

The 3-bed concept with cooling between the

catalyst beds gives high conversion for each

converter pass; since for each bed the achievable

conversion is limited by the equilibrium of the

ammonia synthesis reaction. The pressure drop is

slightly higher but is outweighed by advantage

of higher conversion and lower loop pressure.

An added advantage is that the synthesis gas

chilling duty is shifted from the ammonia

refrigeration circuit to the synthesis loop water

cooler because of higher ammonia concentration

at the converter outlet. The synthesis loop

operation at milder conditions leaves room for

possible future capacity increase. Thus the

ammonia converter with a 3-bed converter

basket was indeed found to be an attractive

option.

Selected Basket

Haldor Topsoe S-300 radial flow converter

basket was selected for installation in the original

ammonia synthesis converter pressure shell,

314 2011AMMONIA TECHNICAL MANUAL


being a highly efficient converter based on three

adiabatic converter beds with inter-bed cooling.

The new S-300 consists of a feed / effluent

exchanger at the bottom (lower heat exchanger -

LHE), a catalyst section comprising three radial

flow adiabatic beds and two inter-bed heat

exchangers (IHEs) in the centre of the upper part

of the catalyst sections, i.e. 1st and 2

nd beds.

The entire inlet gas is circulated through all

converter beds resulting in a higher conversion.

The mechanical design was based on the well-

proven S-200 converter basket. Therefore, the

same reliable operation was expected with the S-

300 converter as with the S-200 design.

No major modifications / replacement of the

shell, piping or other loop equipment were

required, except for the swapping of the internal

inlet / IHE feed gas connections for the new

basket.

A sketch of the S-300 converter basket is

presented in Figure 2.

Figure 2: New S-300 Basket

Gas Flow Path

In the new S-300 basket, there was a change in

the synthesis gas flow distribution from the

original scheme of the S-200 converter (in which

the bulk flow through the main control valve was

passed across the LHE while remaining flow was

directed to the IHE using a separate control

valve). The swapping of converter inlets was

necessary so that the synthesis gas from the main

control valve passed through the IHEs while

remaining gas would be directed to pass across

LHE. This change required drilling in the

pressure shell to accommodate larger size

flexible pipe.

Advantages

The following advantages were foreseen:

� Higher conversion per pass - increased

ammonia production

� Reduced synthesis loop pressure – resulting

in compression-energy saving

� Reduced inert level – lower purge gas rate

� Suitability for future capacity revamps

Two revamp conditions were forecasted at two

inert levels (16.5% and 19.5%), obtaining

maximum converter outlet temperature of 380 °C

(716 °F) and 360 °C (680 °F), respectively; 360

°C (716 °F) being the original design

temperature.

Operating parameters expected after the new

basket installation are presented in Table 1.

Description S-200 S-300

Production rate, MTPD 1345 1368

Converter inlet pressure,

kg/cm2g

266 264

Converter outlet temperature, °C 363 360

Ammonia at converter inlet,

mole%

3.85 3.62

Ammonia at converter outlet,

mole%

17.1 17.24

Inert gases in the loop, mole% 11.67 19.5

Purge gas flow, Nmc/hr 11,876 6,059

Table 1: Operating parameters comparison



Project Planning and Execution

Challenges

The replacement of catalyst and the basket

involved specialized manpower services to work

under Immediate Danger to Life and Health

(IDLH) environment as the entire activity was to

be performed in inert (nitrogen) atmosphere

owing to the pyrophoric nature of the reduced

synthesis catalyst. Vendor qualification was a

significant task due to the critical nature of the

job requiring both well trained manpower to

work under IDLH conditions and special tools

and improved methods and equipment, (such as

high capacity vacuum unit with continuous

unloading) for removing the 18 year old partly

fused catalyst. Moreover, the turnaround was

planned based on the time duration of this

critical job and meticulous efforts were put in to

save time where possible without compromising

on the job quality and safety of both manpower

and the equipment.

Vendor qualification for IDLH

Eight different companies recommended by

Haldor Topsøe were contacted to supply

specialized services to carry out S-200 basket

unloading / removal (under IDLH conditions)

and installation of S-300 basket. Subsequent to

detailed technical and commercial evaluation,

Contract Resources (CR-Asia), Singapore was

awarded the contract to execute the project.

The committed execution schedule offered by

CR-Asia was better than others, with a saving of

turnaround timing by 37 hours. Some salient

features of CR-Asia equipment are given below:

� High capacity vacuum units; one in operation

and second as standby

� Two stage continuous operation cyclone

separation unit

� Metallic unloading pipes to avoid melting /

damage owing of hot pyrophoric catalyst

� Separate cyclone based dust removal system

� Chep-bins (sealed containers having nitrogen

blanketing to avoid heating up of reduced

catalyst)

� Three way redundant breathing air-supply

system (compressor, air cylinders, plant air-

supply plug-in along with small emergency

air-bottles fitted on each heat resistant air-

cooled IDLH suites) for vessel entry

technicians

Pre-Arrangements

CR-Asia visited the plant site in advance and had

a detailed discussion on the job preparation with

FFC project team. CR-Asia team was available a

week before the scheduled turnaround time to

ensure job preparation and pre-requisites

including supplies from FFC. The unloading

system was installed with necessary functional

tests on synthesis converter well before start of

the turnaround activities.

Figure 3: Catalyst Unloading Arrangements

Maintenance shutdowns are a key part of the

annual budget of fertilizer plants and plant

downtime contributes the major chunk of this

cost. Each activity of the S-200 basket

replacement job was given a special

consideration to reduce this plant downtime cost

without jeopardizing safety and quality of the

job. Some breakthrough ideas were emerged,

such as dismantling the S-300 basket outside

pressure shell prior to plant shutdown. While it is

a conventional practice to install the complete S-

300 basket inside the pressure shell and then



remove 1st bed, 2

nd bed and inter-bed heat

exchanger to access and load the catalyst. Thirty

hours of downtime was saved by executing this

activity prior to plant shutdown.

To dismantle the S-300 basket prior to plant

shutdown, the basket along with its transport

container was erected and supported with the

existing pressure shell supporting structure. The

1st and 2

nd bed cartridges, and IHE were removed

one by one from converter basket and placed on

structures designed and erected for this purpose.

These temporary support structures were also

used as working platforms to prepare the bed

cartridges and IHE for installation.

Figure 4: Removed 1st & 2

nd Beds

Rigging Plan

An overhead crane of 50 tons is installed on the

top of Ammonia Converter. This built-in

resource can be utilized for rigging of basket

internals within limited distance. This crane was

insufficient tor installation of the entire

assembled S-300 basket at 50.5 tons. Using a

truck mounted crane to insert S-300 basket

inside pressure shell was risky because of limited

space available on Convertor top. The

dismantling of S-300 basket outside the pressure

shell resolved this matter. By dismantling the

basket, the largest lift load (comprised of the

basket and 3rd bed cartridge), was reduced to 32

tons: well within safe limits of over head crane.

Figure 5: Tailing / Main Crane arrangement for

basket installation

Two truck mounted cranes of 250 tons and 120

tons were also involved in the replacement

activity. Shifting of basket to the site and vertical

erection of the basket was completed with these

cranes, as shown in Figure 6.

Figure 6: IHEs Removal Platform

Special Fixture for Shell Drilling

Drilling of 8 holes of 20 mm (0.79 inch)

diameter (M20 metric) in the pressure shell were



required to accommodate larger size flexible

pipe for the change in synthesis gas flow

distribution.

The material of this multi layered pressure shell

is ASTM A333 Gr. F1. In order to ensure perfect

drilling, a pressure shell mock-up of was built

having similar curvatures, hardness and number

of layers as that of the pressure shell. To

facilitate drilling operation and ensure centricity

of holes, a customized jig was designed with

following features:

� This jig is inserted inside the nozzle and then

it is expanded with a threaded mechanism so

that it can grip the nozzle from inside.

� It provides a rigid and leveled platform for

mounting of magnetic drill machine.

� Holes in the base plate of jig provided

guidance to the drill bit of magnetic drill

machine.

� It ensured bolt circle diameter (BCD) and

alignment of holes with respect to nozzle.

Turnaround Execution

Converter basket replacement job was on critical

path so the plant downtime was directly linked to

it. Due attention was paid to each activity during

planning phase to reduce the job execution

timing. A total time of 476 hrs was planned for

the job including equipment handover.

This was a challenging target compared to the

experience shared by other fertilizer industries

for similar job scopes. Problem encountered at

those locations were given special

considerations. Detailed timings are presented in

Table 2.

Innovative Approaches and Safety Considerations during Vessel Preparation for Installation of S-300 basket

Reactor cooling and purging is a very important

step towards reactor handover. Comfortable

environment for the manpower to work inside

the reactor was given special consideration.

Several ingenious ideas like cooling of the

circulation gas with refrigeration chillers in

service to minimum possible temperature and

passing of gas through startup heater for heat

exchange with ambient air were employed.

These measures proved successful in bringing

down the reactor temperature to below 45 °C

(113 °F) within 12 hours, while maintaining a

maximum cool down rate of less than 50 °C (122

°F) per hour.

S.No. Description Time,

Hrs

1 Shutdown, cooling, purging with N2 44

2 Preparation for catalyst removal 37

3 Removal of catalyst from 1st bed 26

4 Removal of 1

st bed cartridge, 2

nd bed

cover 20

5 Removal of catalyst from 2nd bed 50

6 Removal of S-200 basket from HP shell 16

7 Preparation & Inspection of HP Shell 40

8 Removal of 1

st bed, IHEs, 2

nd bed & 3

rd

bed cover 30

9 Installation of S-300 basket, bottom

forging & Preparation for loading 16

10 Drilling and tapping of threaded holes

in HP shell 28

11 Catalyst loading in 3rd bed 30

12 Installation of 3

rd bed cover & 2

nd bed

cartridge 24

13 Catalyst loading in 2nd bed 13

14 Installation of 2

nd bed cover, IHEs & 1

st

bed cartridge 30

15 Catalyst loading in 1st bed 13

16 Installation of basket &HP covers,

pipes and thermowells 59

Total duration, Hours 476

Table 2: Planned timings

A huge reservoir of liquid nitrogen from local

supplier was made available with maximum flow

rate of purge nitrogen @ 500 Nm3/hr. A number

of purge points at upstream and downstream of

the reactor resulted in very effective, safe and



timely handover of the reactor and synthesis loop

well within the planned duration of 44 hours.

Figure 7: Nitrogen Reservoir

Lifting of pressure shell cover (weighing 7.3

tons) using over head crane was done after

removal of thermocouple junction boxes,

thermocouples, thermo-wells and the stuffing

boxes.

Flexible pipes, 1st bed cover etc. removed to

make the 1st bed ready for catalyst removal.

After installation of temporary lid cover,

necessary connections and sealing nitrogen

circulation was started.

Figure8: Lifting of HP shell / 1st bed covers

With all safety measures, unloading of catalyst

was started under nitrogen circulation. Catalyst

from 1st bed was removed without any

mentionable problem followed by 1st bed

removal. Catalyst unloading from 2nd bed was

started, but the catalyst was badly fused at the

lower bottom. To avoid any delay, it was decided

to lift the basket with some catalyst remaining in

the 2nd bed.

Figure 9: Typical un-loading arrangement

To keep all rigging equipment within safe

capacities, the volume of catalyst was calculated

which could be left inside the 2nd

bed during the

lift. A nitrogen blanket was provided during

rigging to avoid exposure of residual catalyst

with air.

Figure 10: Removal of S-200 Basket



Pressure Shell Inspection before S-300 basket

Installation

After removal of S-200 basket, 8 holes were

drilled in the pressure shell for installation of

new flexible pipes to accommodate new

synthesis gas flow distribution. Inspection of

pressure shell was carried out with following job

scope;

o Visual inspection of complete shell.

o Magnetic Particle Testing of all

circumferential, longitudinal and nozzle

welds

o Hardness testing in HAZ of the welds

o Hydrogen attack survey of bottom shell

up to man height

No abnormality was observed during pressure

shell inspection.

S-300 Installation and Catalyst Loading

The new S-300 basket was installed inside the

original pressure shell and loaded with HTAS

pre-reduced ammonia synthesis catalyst (KM1R)

using proprietary HTAS loading method.

Figure 11: Insertion of S-300 Basket

Centricity of basket in the shell is ensured by the

centering wedges installed on outer periphery of

basket top. To ensure verticality of basket in

pressure shell, lead bars were placed at basket

support ring installed at the bottom of pressure

shell. Cables attached to these lead bars were

accessible from bottom outlet pipe. The basket

was inserted inside the pressure shell using

overhead crane and placed on its support ring.

When it was ensured that load has been released

from the crane, the basket was lifted again to the

elevation of 2000 mm. Lead bars were pulled out

from bottom outlet pipe and its thicknesses were

measured. The deviation in thicknesses of these

lead bars was found within acceptable limit.

Then the 3rd bed was ready for loading of

catalyst.

Catalyst Loading

Catalyst loading was performed in accordance

with Topsoe’s recommendation utilizing their

proposed method.

Pre reduced synthesis catalyst type was loaded in

all three beds. The quantity of catalyst loaded is

given in Table 3.

Bed No Catalyst, m3

1st [Upper] 6.3

2nd

[Middle] 6.3

3rd [Bottom] 17.1

Table 3: Catalyst Details

Screening of the catalyst was done to remove

dust using two conveyer systems with vibrating

screens directly discharging into the loading

bins.

Four loading points were used simultaneously

taking suction from four way outlet nozzle of the

feeding hopper fixed on the top of the S-300

basket on a special fixture made exclusively for

this purpose by FFC maintenance team.

Figure 12: Loading Points (4 Nos.)



After catalyst loading and the closure of the 3rd

bed, the 2nd

bed was installed and loaded with

catalyst. The IHE was installed, followed by

installation and loading of 1st catalyst bed and

final closure of the 1st bed and S-300 basket.

The loading activity was fast and smooth with

satisfactory results of densities achieved

resulting in higher than anticipated catalyst

weight loaded in each bed of S-300.

Commissioning

Subsequent to completion of maintenance

activities and other turnaround jobs, start-up of

the ammonia front-end was commenced on

October 27, 2009. After availability of synthesis

gas from front-end on October 29, 2009,

commissioning of the new S-300 basket and

catalyst was carried out. The overall

commissioning activity, though longer than

anticipated, was smooth.

Converter Blowing / Catalyst Activation

The very first step in the commissioning was to

blow the small quantity of dust from newly

installed catalyst generated during the loading

activity. This was done at a loop pressure of 100

kg/cm2g (1422 psig) by opening of maximum

possible purge points / vents in the loop.

After completion of the blowing activity, the

new stabilized synthesis catalyst (supplied in

partially oxidized form) was activated by

controlled heating of the catalyst with synthesis

makeup gas containing hydrogen through the

help of startup heater and at pressure level of the

synthesis loop.

The oxygen fixed on the catalyst during its

stabilization is removed when the catalyst is

exposed to the hydrogen containing atmosphere

and heated-up. This process leads to complete

reduction [or activation] of the catalyst.

Activation steps of the catalyst consisted of

mainly four steps as given in Table 4.

Step

Max Temp

°C

Rate

°C/hr

Pressure

kg/cm2

Time

hrs

1 250 30 - 50 80 06

2 250 - 400 15 - 25 80 08

3 400 - 500 10 - 20 80 - 150 12

4 Start-up heater

is taken off

- 150 04

Total duration (hrs) 30

Table 4: Activation Steps

The water produced during the activation of pre-

reduced catalyst was disposed off in compliance

with the company environmental practices.

The advantage of using pre-reduced catalyst was

that it became active in an early stage resulting in

the following advantages:

• Early production of ammonia (much less

time required compared to oxidized

catalyst).

• Ammonia synthesis reaction starts some

time before completion of the catalyst

reduction. Consequently, latter part of

reduction process was faster.

The activation of catalyst was continued from

October 29-31 (for 60 hours) and ammonia

production was aligned with storage when the

concentration of ammonia from separator

reached above 30%. The later part of 3rd bed

reduction was slow owing to completion of

reaction at the upper beds and it continued till the

time when reactor outlet ammonia concentration

reached from 13% to around 16% in the

following two weeks.

The reduction activity was supervised by two

Haldor Topsoe engineers along with FFC’s

process engineers with closed monitoring of bed

temperatures and other plant parameters.



Figure 13: Temperature profile showing the

reduction activity

Operational Experience

Operation of the new 3-bed basket and catalyst

was entirely satisfactory and the plant observed

1380 MeT per day ammonia production with

conversion efficiency of around 29% per pass,

thus surpassing the previous best records within

two weeks of the commissioning. Subsequent to

completion of another project for natural gas

(feed) compression, with availability of more

feedstock gas the plant load was increased to

around 116% of the revamped capacity (141% of

the original nameplate capacity). However,

limitations in the synthesis loop were observed

especially in the reactor hot spot temperatures

i.e. 1st bed outlet temperature approaching 540

°C (1004 °F) and also in the synthesis gas

compressor speed owing to higher synthesis loop

pressure of 260 kg/cm2g (3698 psig). This

limited the further increase in plant load despite

availability of natural gas.

Efforts were undertaken by FFC’s team to look

into options for S-300 converter optimization.

The focus was given to the bed temperature

profile adjustment with the help of a model

developed exclusively for 3-bed converter basket

using in-house simulation facilities.

First Optimization (November, 2009)

Ammonia plant operating data was input in the

detailed backend model developed for this

purpose to observe the actual performance of the

converter and identify possible improvement

areas.

Comparison of simulation and actual plant data

was carried out, along-with plot of ammonia

concentration at each bed. Following

observations were made;

• Owing to higher inlet temperature of 415

°C (779 °F) and therefore higher rate of

reaction, the outlet ammonia concentration

from the first bed was higher causing the

lower two beds to run under-utilized.

• Similarly the 2nd

bed and 3rd bed

temperatures were also running higher than

optimum causing the exothermic reaction

to shift on the negative side especially

when low inlet temperatures are more

favorable for a new active catalyst.

• The hydrogen to nitrogen ratio at converter

inlet needed further optimization to bring

down its value to 2.9-3.0 which is the most

optimum range for maximum theoretical

conversion.

Based on the above analysis, new conditions

were put into the S-300 model. The simulation

results revealed that these changes would bring

the reactor close to the most optimum operating

conditions. The expected improvements were

lower loop pressure, increased ammonia

production even with higher inert level (20%)

and lower purge rates.

These observations along with simulation results

were discussed with plant operation team for

review of practicality and actual test for the

reactor optimization was undertaken on

November 21, 2009 with frequent lab analysis

and data logging.

The reactor bed temperatures were decreased in

smaller steps and further steps were undertaken

subsequent to normalization of intermediate

conditions, which took about a week. Peak

performance of the S-300 converter basket was

achieved after completion of the intended



changes in the reactor temperature profile. A

comparison of the pre-post optimization

operating conditions is given in the Table 5:

The effect of optimization on the synthesis loop

was evident as synthesis loop pressure started

decreasing immediately with increase in the

overall temperature rise across the S-300

converter. This in turn gave operations the

flexibility to increase the speed of synthesis

compressor with increasing throughput when

further margin became available.

Second Optimization (February, 2010)

A second attempt was made to optimize the S-

300 converter in the month of February 2010 to

utilize favorable low cooling water temperatures.

This time, the simulation included actual plant

data on the backend model. The results indicated

a further margin of lowering bed temperatures

with improved conversion efficiency. The

optimization on actual plant operation was

undertaken with careful adjustment of bed

temperature profile i.e., lowering by 2-3 °C, inert

level in the loop and purge rates; details given in

Table 5. As a result, loop pressure further

decreased to around 253 kg/cm2 (3598 psi) while

conversion efficiency increased to 34% giving

further margin to improve plant throughput.

Description Before

Optimization

1st

Optimization

2nd

Optimization

Production rate, MTPD 1400 1478 1492

Recycle gas flow, Nmc/hr 641,000 642,400 634,400

1st bed temp (oC) Inlet / Outlet 415/540 391/526 393/526

2nd bed temp (oC) Inlet / Outlet 495/515 488/516 461/497

3rd bed temp (oC) Inlet / Outlet 436/477 433/476 406/448

Inlet pressure, kg/cm2g 261 255.4 253.5

Purge gas flow, Nmc/hr 8,400 8450 8931

Conversion per pass, % 30.04 33.26 34.28

Table 5: Operating parameters before and after

optimization

The operating performance of the ammonia

synthesis converter with new S-300 basket

exceeded the predictions regarding ammonia

production rate. Moreover other operational

parameters also remained as expected or better

despite plant operation at higher load. This was

possible after extensive optimization carried out

by FFC team after completion of the catalyst

reduction activities. A record ammonia

production of 1492 MT/day was achieved.

Conclusion

With concerted efforts, excellent planning and

preparations, the new S-300 basket project was

not only accomplished well before the scheduled

time but also in-house optimization efforts

proved successful in realizing its excellent

performance. The introduction of the new S-300

basket at the Ammonia-I plant proved very

successful in overcoming backend limitation

problems and resulted in boosting the ammonia

production rates. The capacity factors are given

below.

Figure 14: Ammonia-I capacity factor profile

After the successful implementation and

commissioning of S-300 converter basket along

with other modification including new tubes in

the primary reformer, retrofit of the ammonia

separator with vane type and replacement of the

synthesis gas cooler with SS re-tube bundle, the

result was an increase in ammonia production

and energy improvement of ~5% [i.e. 8.40

Gcal/MT (30.2 MMBtu/sT) achieved compared

to 8.85 Gcal/MT (31.9 MMBtu/sT) before

turnaround 2009].



Documents

Optimizing the Installation and Operation of a New 3-Bed