PRODUCTION OF AMMONIA - OCI Nitrogen

4. ENVIRONMENTAL DATA
Environmental data for the BAT production processes are generally known with a high
degree of reliability, while data for storage and transfer are more uncertain and of much less
importance. Hence, data for production will be given the highest attention.
4.1 Production Input Requirements
4.1.1 Feedstock
The typical feedstock requirements for modern plants are (approximately):-
Conventional reforming: 22.1 GJ(LHV*).t -1 NH 3
Excess air reforming : 23.4 GJ(LHV).t -1 NH 3
Autothermal reforming : 24.8 GJ(LHV).t -1 NH 3
Partial oxidation : 28.8 GJ(LHV).t -1 NH 3
* Lower Heating Value
4.1.2 Fuel
Assuming an efficient stand-alone plant with no energy export and no other import than feedstock
and fuel, the fuel requirements are (approximately):-
Conventional reforming: 7.2-9.0 GJ(LHV).t -1 NH 3
Excess air reforming : 5.4-7.2 GJ(LHV).t -1 NH 3
Autothermal reforming : 3.6-7.2 GJ(LHV).t -1 NH 3
Partial oxidation : 5.4-9.0 GJ(LHV).t -1 NH 3
The uncertainty in autothermal reforming is mainly due to the type of compressor drives.
4.1.3 Water and air
In the steam reforming processes process steam is taken from the plant steam system, usually
from an extraction turbine. The net consumption according to the stoichiometic conversion is
0.6-0.7kg.kg -1 NH 3 , the total supply at a S/C ratio of 3.0 will be about 1.5kg.kg -1 NH 3 . In partial
oxidation much less steam is fed to the gasification reactor, but additional steam is needed
in shift conversion (1.2kg.kg -1 NH 3 in total).
Process air supply: In conventional reforming the nitrogen supply equals the ammonia nitrogen
content plus the purge losses, ie. about 0.85kg N 2 .kg -1 NH 3 or about 1.1kg air.kg -1 NH 3 . In
the excess air reforming and gas heated reformer cases the process air requirements are about
50% and 100% higher, respectively. In the partial oxidation process the amount of air fed to
the air separation unit is approximately 4kg.kg -1 NH 3 , based on the oxygen requirement.
Boiler feedwater: Assuming all steam condensates are recycled, only the process steam consumption
has to be replaced by outside water. This will be 0.7-1.5kg.kg -1 NH 3 (see above),
depending on process condensate recycle or not. Small additional losses and potential
import/export have to be allowed for in practice.
Air and/or water for cooling: Will differ from one site to another.
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