This article relates to ammonia manufacturing process technologies used in industries,there differences and similarities.

1. Description of ammonia manufacturing processes
Sameer Pandey1
National Fertilizers Limited ,Naya Nanagal, Ropar,Punjab,140126
Abstract: This paper presents technical information related to industrial manufacture of ammonia. Various processes
and operating parameters are discussed. Ammonia is ther main component for Urea formation , hence study of its
manufacturing processes is immensely important and usesful.
INTRODUCTION:
Haber and bosch are credited with the invention of modern day ammonia synthesis process, they
were awarded the nobel prize for their contribution to mankind. The process involves reaction of
nitrogen and hydrogen in a high pressure , moderately high temperature reactor, in presence of iron
catalysts. The design and composition of catalyst is quite complex. Ammonia was first
manufactured by BASF plant at Oppau, Germany. BASF researcher Alwin Mittasch is credited with
inventing the iron based catalyst.
The reaction is as follows:
N2 + 3H2 ↔ 2NH3
The reaction is exothermic with a heat of reaction around 45 KJ/mole .
Main source of nitrogen is air and source of hydrogen is natural gas, the reaction ocuurs around 200
atm pressure and 400 o
C. The reaction rate constant increases with decresing temperature but the
temperature cannot be set low as kinetics start to play its role on the reaction.
HALDOR TOPSOE AMMONIA PLANTS:
The topsoe plant differs from other technology in the design of reformer and carbondioxide removal
system, other steps like desulphurization, CO shift conversion, methanation and ammonia synthesis
steps are very similar.
The reformer in topsoe plants are side fired, the reformer section is divided in two parts, making the
total number of walls four. There are six rows of burners along each wall with 9 burners in each
row, since there are four walls the total burners are 216.
Steam to carbon ratio is 3.0 and methane slip from primary reformer is around 12.5%.
methane slip afeter secondary reformer is around 0.6%.
The air in secondary reformer is maintained so as to get H2/N2 ratio of 3.
For carbondioxide removal haldor topsoe offers various choices like activated MDEA process, Gv
process, Benfield Process.

2. Uhde AMMONIA PROCESS:
The primary reformer in this process is top fired and it may involve one or two synthesis converters,
the main difference is in method used for carbon diocide removal. Uhde recommends use of
activated OASE WHITE®
(aMDEA®
)licensed by BASF. This process combines both effects of
physical and chemical absorption. The major design difference is use of two synthesis converters in
order to maximise conversion. Large catalyst volume is used, the reactors consist of three beds, two
in one reactor and other reactor of single bed, and radial flow is used. Uhde says the energy
consumed is around 6.4 to 7.2 Gcal/MT ammonia.
KELLOG BROWN AND ROOT AMMONIA PROCESS:
The process involves cryogenic purification technology named KBR PURIFIER®
to maintain
H2/N2 ratio for synthesis of ammonia. The front end and Back end are thus independent of each
other because of the purifier. Primiary reformer is top fired, with 3 bundles of tubes containing 44
tubes per bundle. Total four burner bundles are present with 14 burners in each burner. Additional 4
tunnel burner are present towards bottom of reformer, they maintain the tempreature of flue gas
around 1000 o
C for heat recovery and steam generation section.
Steam to carbon ratio is around 2.8.
The feature of using excess air in secondray reformer shifts the load from primary reformer thus
increasing the life of tubes.

3. LINDE AMMONIA CONCEPT (LAC) PROCESS:
The process uses natural gas or light hydrocarbons for production of ammonia, Gas purification
system is PSA(pressure swing adsorption), no secondray reformer is present. Plant capacities upto
1350 MTPD have been installed using the concept. LAC uses Casale's ammonia radial flow
converter. First plant was installed for GSFC gujrat in 1998.
Source:
https://www.linde-engineering.com/en/process_plants/hydrogen_and_synthesis_gas_plants/gas_products/ammonia/index.html
The nitogen producing unit is separate, and nitrogen is added upstream of syngas compressor.
ICI'S LEADING AMMONIA CONCEPT(LCA) PROCESS:
Imperial chemical industries started two identical plants based on LCA process in 1988. The plant is
divided in two plants, the core plant and the utilities plant. Core plant uses gas heated reactor and
s/c ratio is around 2.5 . Primary reformer is heated by the gas exiting secondary reformer. Use of
isothermal shift converter eliminates fisher-tropsch reaction. Ammonia reactor is based on ICIC's
cobalt catalyst. Pressure in synthesis reactor is around 80 ata.

4. This process is not in so ,much use nowadays.