Industrial Gases
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OVERVIEW
Industrial gases may actually be used as gases, liquids, or cryogenic liquids. Industrial users generally accept them as those gases used primarily in their pure form in large quantities. Most of the gases we consider to be indus-
trial gases have been in use for many years. Processes for the cryogenic separation of the air gases were developed as early as 1895 with commercial production of oxygen begin~ ning in 1902. Nitrous oxide was used as an anesthetic as early as 1799. Carbon dioxide had been identified as a specific substance by 1608. Methane has been used as an energy source since the 1700s. The reactivity of gases can be summarized into three classes: oxidizers, inert gases, and flammable gases. The gases that fall into the category of inert are nitrogen, argon, helium, and c~rbon dioxide. The oxidizers are oxygen, chlonne, and nitrous oxide. Acetylene, *Process Systems Consulting, Inc.
s
Riegel Handbook of Industrial Chemistry, 1Oth Edition
Edited by Kent. Kluwer Academic/Plenum Publishers, New York 2003
liquefied natural gas (LNG), and hydrogen are the flammable gases. These elements and compounds by no means encompass all gases considered to be industrial gases, but they represent the major gases used and produced in industry (see Table 13.1). 1 The cryogenic air separation process in which air is liquefied and separated int~ its major constituents (oxygen, nitrogen, argon) by .the use of cryogenic technology, is the maJor source of nitrogen, oxygen, and argon produced for industry, as well as the noble gases Krypton, Neon, and Xenon. Table 13.2 gives the cryogenic boiling point temperatures and concentrations for some of the gases present in the atmosphere. The cryogenic air separation process starts with air entering the plant through air filters where it is compressed and cooled. The air i~ passed through heat exchangers for further cooling and for removal of water vapor and carbon dioxide by freezing. Solid adsorbents, such as molecular sieves, silicas, and aluminas can also be used to remove the water and carbon dioxide by adsorption before separation of 463
psia
Critical point
p.408
8.72
p.415
191.7
191.6
p.416
1.42
1.38
3.425
4.43
4.42 3.555
0.083
0.00521
-399.93 190.8
-434.55 1.045
-423.0
2.016
Normal Hydrogen (n-H)
0.084
0.00521
-400.31 187.5
-434.8 1.021
-423.2
2.016
Para-hydrogen (p-H)
p.234
88.2
1.40
0.241
54.56
0.2805
0.07493
-221.1 547
-317.8
28.975
Air
p.528
85.6
1.41
0.249
50.48
0.2879
0.072
-232.4 493
-346.0 1.81
-320.4
28.01
(N)
Nitrogen
p.555
91.7
1.40
0.2197
71.23
0.2795
0.08279
-361.8 0.0216 -181.4 731.4
-297.3
31.9988
Oxygen (0)
p.262
69.8
1.67
0.125
87.02
0.3606
0.103
-308.8 9.99 -188.1 711.5
-302.6
39.95
Argon (Ar)
p.296
245.5c
1.304
0.203
73.5d
0.1462
0.1144
87.9 1070.6
-69.9 60.4
-109.33C
44.01
Carbon Dioxide (CO)
NTP = 14.696 psia and 70°F; STP = 14.696 psia and 32°F; Lb/cf= pound per cubic foot. •Lower lambda point; hNIST Technical Note 631, "Thennophysical Properties ofHeliu
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