Ammonia synthesis revamps

John Brightling

25 Mar 2015

Westin Hotel Gurgaon, India

Targets and Requirements of a Revamp

Typical targets for a revamp of a fertilizer plant:

Capacity increase

Reduction of operating cost / energy consumption

Environmental improvements (e.g. reduction of emissions)

Increase of reliability and availability

Change of Feedstock

Important things to consider to make the project a success:

Use a well proven and reliable technical concept

Keep the plant downtime for implementation and modification as short as possible

Reactor development

3

Max Appl, IFA Technical Conference, September 25.-26., 1997, Sevilla, Spain

Equilibrium curve

% NH3

Temperature C

500 450 400 0

5

10

15

20

Quench Heat exchange

heat exch.

Converter Retrofits

Interchanger rather than quench

Convert to axial-radial or radial flow

Utilise smaller catalyst

Since reaction is diffusion limited increases reaction rate and therefore increased production

Can improve efficiency by 0.5-1.0 GJ/t

Most plants have done this

Reactor development

5

Particle Diameter (mm)

14 12 10 8 6 4 2 0

Rela

tive A

cti

vit

y

120

100

80

60

40

0

20

Additional Converter Volume Options

A couple of revamp options:

Booster converter in the synthesis loop

Once through synthesis converter

Booster converter (e.g. additional 4th bed)

Equilibrium

3 bed converter

4th Bed booster

WC Synthesis Gas

(Make up gas) WC

NH3 - Synthesis

Loop

Purge Gas

1 2 3 R

S

S: Separator

WC: Water Cooler

CH: Chiller with

NH3-refrigerant

S

NH3 Product

H2O

HP Steam

CH CH CH

Synthesis

Reactor

NH3 -

Once Through

Synthesis

H2O

Booster low pressure OT Scheme

Revamp Case Study 1 - Once through

Duslo Ammonia Plant 950 TPD Europe, build 1973

Desire to increase plant capacity by 40%

New once through converter by Uhde

Two radial beds KATALCOJM 74-1 catalyst with one interchanger

Additional capacity by reactor 385MTPD

Duslo, Slovakia

Original Front End & Loop

HP steam

Feed

MP steam

Process air

Combustion air

CW

BFW

CO2 -removal

CO2

Refrig.Unit

BFW

FuelGas

ProductAmmonia

New Once Through Booster

HP steam

Feed

MP steam

Process air

Combustion air

NH3

CW

NH3

SynthesisLoop

BFW

CO2 -removal

CO

2

RefrigerationPackage Unit

BFW

BFW

Purge Gas

H2Recovery

FuelGas

AmmoniaWater

Product Ammonia

Four-Phase Revamp Project Execution

Test Run -> mass balances, Temps, Pressures

Precise pressure drop review

Catalyst performance data

Control valve survey

Maximum load tests

Discussions with operation staff

Plant simulation with gathered data

Revamp Study

Description of the revamp concept

Process Flow diagrams (PFD)

Steam Balance

Production and consumption figures

Cost estimate (+/- 15%)

Revamp Study

Study results:

Four-Phase Revamp Project Execution

Equipment / piping Specifications

Piping and Instrumentation diagrams (P&ID)

3-D modelling of plant

Operating handbook / analytical manual

Consumption / effluents / wastes

Plot plans

Cost adjustment / confirmation

Basic Engineering

BEP results:

Four-Phase Revamp Project Execution

Revamp concept checked and confirmed

Detailed configuration of the plant

Selection of equipment suppliers begins

Long delivery items ordered

Licenses acquired / updated

Safety aspects explored

Basic Engineering

Four-Phase Revamp Project Execution

OT Synthesis advantages for revamps

Energy efficient

Tie-In work completed during scheduled downtime

Minimisation of downtime during Revamp

Start-up any time plant is in operation

Shutdown/isolation from running plant

Spatial Integration not necessary

OT Synthesis Spatial layout

Revamp Case Study 2 - Booster

Kuibyshev Azot OJSC

Plant 1360TPD GIAP Russian, build 1977

Operating at 1600 TPD desire to increase plant capacity to 1800 TPD

The plant is a standard GIAP design of the 1970s.

Several dozen of this plant type exist in Russia

and other states of the former Soviet Union

Revamp Case Study 2 - The Customer

Kuibyshev Azot, Togliatti, Russia

Kuibyshev Azot OJSC:

Profile of the Original Ammonia plant: - fairly conventional process applicable to the whole family of such plants:

top-fired primary reformer with internal riser pipes

bayonet-type HP steam boiler downstream of the secondary reformer

CO shift with one vessel for HT and two parallel vessels for LT shift

MEA CO2 removal system

Standard methanation

synthesis gas compression by steam-turbine driven centrifugal compressor

synthesis loop with one ammonia converter

Modifications made in earlier revamp:

change from MEA to activated MDEA as CO2 removal solvent

new ammonia converter cartridge with axial/radial flow pattern

Revamp Case Study 2 - The plant

Ammonia plant block diagram before the revamp:

Revamp Case 2 Plant before revamp

natural

gas

air

steam

steam

BFW

ammonia

steam

process air

compressor

pre-

heating

metha-

nation

desulphu-

rization

pre-

heating

primary

reformer

secondary

reformer

gas

cooling

CO2

removal

gas

cooling LTS

gas

cooling HTS

synthesis

loop

refrige-

ration

syngas

compressor

(1st + 2nd stage)

syngas

compressor

(3rd + 4th stage)

synthesis gas generation

ammonia synthesis purge gas

proc. air

preheater

CO2 BFW BFW

Kuibyshev Azots target for the revamp:

production increase to 1,800 tons per day (+ 12.5 % on current / + 32 % on original nameplate capacity)

improved energy efficiency of secondary importance

Technical solution: main changes in syngas generation (front end):

Removal of fired heater for feed preheating, replacement by new preheat

coil in reformer flue gas duct

addition of blower to suction side of process air compressor

lower steam-to-carbon ratio

New feed / steam coil in flue gas duct to increase feed / steam inlet

temperature

Revamp Case 2 The revamp

Case Study 2: Synthesis Section

Water Removal from Synthesis Gas

Can use either molecular sieves or ammonia washing

Then feed synthesis gas to converter inlet

Reduces ammonia content of gas inlet converter therefore increases production

Reduced refrigeration load

No loss of reactants in purge gas

Technical Solution in Synthesis (1 of 2)

Technical Solution in Synthesis (2 of 2)

KATALCOJM 74-1 - Stability & Longevity

User Technology Operating

Terra Severnside, UK (closed) LCA 2 20 years

Puyang, Henan, China Uhde 20 years

Terra Severnside, UK (closed) LCA 1 15 Years

CBC, Hainan, China Casale 19 years+

CF Courtright, Canada AMV 17 years +

Orica, Australia Casale 14 years+

Incitec Pivot, Australia KBR/Casale 13 years+

SAFCO, Saudi Arabia Uhde 8 years+

Duslo, Slovakia Uhde 7 years+

Saudi Mining, Saudi Arabia Uhde 4 years+

Dyno, Australia Casale 2 years+

Case Study 3 : Casale Revamp

Ammonia Plant 800mtpd

KBR 4th bed booster converter installed in 1997

Used KAAP catalyst Ru on activated carbon substrate

KAAP catalyst rapidly degraded resulting in a loss of activity, loss

in plant capacity and loss of

catalyst from the reactor

Reactor converted by Ammonia Casale to use KATALCOJM 74-1

Case Study 2 : Casale Revamp

Relative Inhibition of

Ru and Fe Catalyst

Ammonia, Appl 1999

Case Study 2 : 4th Bed duty

N2+3H2 2NH3

N2+3H2 2NH3

Ru

Fe

Reacti

on

Rate

Ammonia %

Proven performance - catalysts

= KATALCOJM 35-series

~36

= KATALCOJM 74-series

~8

= KATALCOJM S6-10

(equivalent to 35 series)

~19

Proven performance - converters

= Kellogg/KBR ~9

= Topsoe ~1

= Casale ~20

= ICI ~3

= Uhde ~24

= Other ~5

BFW

Make-up gas

Syngas compressor

Refrigeration Purge

NH3

( liquid )

HP steam

C.W.

New large plants

2200mtpd TKIS Uhde 2 converter 3 bed, inter-bed HP boiler

BFW

Make-up gas

Syngas compressor

Refrigeration Purge

NH3

( liquid )

HP steam

C.W.

2200mtpd TKIS Uhde KATALCOJM 74-1 in Bed 2 and 3,

Loop pressure can be reduced 4% Additional production of 25,000te/year

New large plants

Johnson Matthey ammonia synthesis

..most efficient plants

..largest plant operating

..largest plant being built

Technical services

Catalyst developments

Thank you