220 ANNUAL, EfiPOET SMITHSONIAN INSTITUTION, 1923 



The equation for the reaction is CO +H 2 +II.,0:=C0 2 +2H 2 , and it 

 is caused by letting an additional quantity of steam react on the gas 

 in a special converter, also with the help of a suitable catalyst. The 

 advantage of this method is obviously that twice the amount of 

 hydrogen is obtained with the same gas producer. The pressure is 

 obtained with no extra cost because the gas must sooner or later, 

 anyhow, be compressed to a still higher pressure, as previously stated. 



Pure hydrogen can be produced by electrolysis of water, but in 

 order that this method shall be commercially feasible cheap power 

 is essential. 



The process used at the Government Synthetic Ammonia Plant at 

 Sheffield, Ala., was a modified water-gas process by which the hydro- 

 gen and the nitrogen is produced simultaneously. It is thus possible 

 to directly provide a mixture in the right proportions, if instead of 

 steam, a mixture of air and steam is passed over the incandescent 

 coke in the gas producer ; or, in other words, if instead of water gas, 

 a semiwater gas is produced consisting of 5 volumes of hydrogen, 

 7 volumes of carbon monoxide, and 4 volumes of nitrogen. After 

 the 7 volumes of carbon monoxide have been converted into 7 vol- 

 umes of carbon dioxide and hydrogen, in the manner previously 

 explained, and the gas freed from carbon dioxide, then it contains 

 evidently 12 volumes of hydrogen and 4 volumes of nitrogen or 

 hydrogen and nitrogen in the correct proportions, 3 : 1, for ammonia. 

 The following equations will possibly make this clearer: 



Steam Air 



5H 2 0+7C+4N 2 +0,=5H,-f7CO+4N 2 

 7C04-7H 2 6=7C0 2 +7H, 



Adding the hydrogen and nitrogen values from the right-hand 

 side of these two equations, we thus get 5H 2 +7H 2 -f-4N 2 =12H 2 -{- 

 4N 2 =8NH 3 . In the German Haber plants the hydrogen is produced 

 by the water-gas method and the nitrogen by separate lean-gas 

 producers. Some free nitrogen is also required around the plant 

 for various purposes, especially for adjusting the hydrogen-nitrogen 

 mixture before it enters the synthetic reaction chamber. This nitro- 

 gen is made by the liquid-air distillation method. This process 

 could, of course, be used for manufacturing all the nitrogen re- 

 quired, but it is a question whether it will be economical unless 

 cheap power can be obtained for driving the refrigerating com- 

 pressors. 



The gases, after leaving the respective producers, are first thor- 

 oughly washed by water separately. The main purification, however, 

 is done after the gases have been mixed, and consists in first wash- 

 ing the gas with water under a pressure of around 25 atmospheres 

 for removing the bulk of the carbon dioxide. After this the gas is 



