Air Separation plant in Steel production industry

Large capacity steel production industries consume three industrial gases, namely nitrogen, oxygen and argon. These are produced in air separation plant present in the utility section. Each of these gases is used for performing the typical operation, like for blowing and heating operation in LD converter oxygen is used. In case of blast furnace top cleaning and coke cooling nitrogen is used and finally, argon is used for agitation of molten liquid form steel and for steel homogenization.

Continuous column operation in air separation plant:

Column of air separation plant

Oxygen consumption:
On ideal base calculation for a 3 MT steel industry oxygen consumption on daily basis is done in the following operations;

CONSUMERS3.0 MT STAGE REQUIREMENTS
 Yearly106 N cumDaily103Ncum
LD Converters blowing & LD Vessels heating189.20540.60
General purpose uses of SMS9.4627.00
Rolling Mills2.004.94
Blast Furnace1.013.60
Repair shops and others1.595.14
TOTAL203.6581.28

Nitrogen consumption:
For purging of pipelines and LD converter gas cleaning system and pressurization of top charging systems of the bell-less blast furnace, dry quenching of coke, and for are done by using nitrogen.

CONSUMERS3.0 MT STAGE REQUIREMENTS
 Yearly 106 N cumDaily 103 N cum
Blast furnace321.46919.20
LD Gas cleaning plant & Continuous casting dept22.6864.80
Pipeline purging & others51.485420.012
TOTAL395.6251404.012

Argon consumption:
Argon is used for welding in the repair shops and stirring of liquid steel in the teeming ladles.

CONSUMERS3.0 MT STAGE REQUIREMENTS
 Yearly 106 N cumDaily 103 N cum
CCD of SMS0.2520.72
Miscellaneous like repair shops, in site repairs etc.,0.020.05
TOTAL0.2720.77

A typical standard air separation plant performance at below condition would be
Pressure: 760 mm Hg
Ambient temperature: 45.3° C max, 10.5° C min
Design temperature: 36° C
Relative humidity (%) : 100 (max), 4 (min)
Design humidity: 59 %

Production rate for the air flow rates (Nm3/hr):

Flows:Mixed RunGaseous Run
100%110%100%110%
Treated air flow (Nm3/hr)950001050008840097300
Oxygen Purity Flow (Nm3/hr)- gas %- liquid%

99.5

127509851402510721480011016280110
Pressure (kg/cm2abs)

1.533

Temperature (° C)

25

Nitrogen Purity %Flow (Nm3/hr)- gas %- liquid%

99.9

255001002805011029600-32560-
Pressure (kg/cm2abs)

1.07

Temperature (° C)

25

Liquid Argon Purity %Flow (Nm3/hr)

99.99

100

110

100

110

Air compressor flowsheet in control panel of air separation plant