750 



NATURE 



[August 12, 1920 



mental station was established at Calgary in the 

 autumn of 1918, and, starting- with the knowledge 

 acquired through the preliminary operations at 

 Hamilton, rapid progress was made in developing 

 a rectification and purifying column, together 

 with the requisite auxiliary equipment, which 

 would efficiently and cheaply separate the helium 

 from the natural gas. 



Development of the Rectification Column. 



In proceeding to develop an equipment for 

 separating the helium from the other constituents 

 of natural gas, three lines of attack appeared to 

 be open, namely, (a) by producing the refrigera- 

 tion necessary to liquefy all the gases except the 

 helium by the cold obtainable from the natural gas 

 itself, (h) by using external refrigeration entirely, 

 such as that obtainable with ammonia, carbon 

 dioxide, liquid air, liquid nitrogen, etc., and (c) 

 by combining methods (a) and (b). 



The last method had been successfully used for 

 the production of helium by the naval authorities 

 of the United States in the Texas field, but from 

 the information supplied it did not appear that 

 this process could be considered to be an eco- 

 nomical one. 



The preliminary experiments at Hamilton, 

 Ontario, made it abundantly clear that method (a) 

 was very promising and hkely to be both efficient 

 and economical. This method was therefore 

 adopted. It was evident from the start 

 that to produce an efficient method the 

 main difficulty to overcome would be the 

 securing of a proper balance between the 

 heat exchangers, the liquefier, the vaporisers, 

 and the rectification portions of the machine. A 

 machine was therefore designed, constructed, and 

 supplied with piping which possessed great flexi- 

 bility, and, in its general scheme, followed the 

 lines of the Claude oxygen-producing column. It 

 is unnecessary to go into details regarding the 

 operation of this machine. It will suffice to say 

 that it was tested under a variety of conditions. 

 Notes were taken of the temperatures reached at 

 different points in the machine under equilibrium 

 conditions when the gas was passed through it in 

 various ways. As a result of this procedure, it 

 was soon found what parts of the machine could 

 be eliminated and what parts could be modified 

 with advantage. When those changes were made 

 which seemed desirable in the light of the ex- 

 perience gained, it was found, that a machine had 

 been evolved which would give highly satisfactory 

 results. 



In operating with this machine, it was found 

 that helium of 87 to 90 per cent, purity could be 

 regularly and continuously produced. 



Operations. 



The experimental machine just described was 

 used continuously for a series of trial runs from 

 December i, 1919, to April 17, 1920. In making 

 a run, about 500,000 cubic feet were passed 

 through the machine, and from this amount up- 

 wards of 20,000 cubic feet of the gas, containing 

 NO. 2650, VOL. 105] 



5 to 6 per cent, of helium, were obtained. As this 

 low-grade product was made it was stored in a 

 large balloon, and the residual gas was passed 

 back into the mains for use in the city of Calgary. 

 The 5 to 6 per cent, product was compressed to 

 from 20 to 30 atmospheres, and then passed 

 through vaporisers. The amount of final product, 

 of 87 to 90 per cent, purity, obtained in each run 

 rose steadily in the course of the operations from 

 about 300 cubic feet to more than 700 cubic feet 

 per run. From this it will be seen that the 

 efficiency obtained with each of the two operations 

 was about 67 per cent. In special runs made 

 under exceptionally good conditions a still higher 

 efficiency was obtained. One of the curves given 

 in Fig. I shows that the purity of the high-grade 

 final product was steadily maintained in the series 



H£UUM ffUNS /IT C/iLG/iPy 



flun Numper 

 Fig. I. 



of runs, and the other curve exhibits the steady 

 increase made in the production of helium of high- 

 grade purity. 



High-grade Purification. 

 When it was seen that the highest purity obtain- 

 able with the experimental machine under actual 

 running conditions was about 90 per cent., steps 

 were taken to design and construct an auxiliary 

 piece of apparatus for raising the purity of the 

 gas up to 99 per cent, or higher. This apparatus 

 as constructed could be used, not only for 

 obtaining a product of high purity at the works, 

 but also for purifying helium which became con- 

 taminated with air by use in balloons in service. 

 Through numerous delays experienced in obtain- 

 ing delivery of tubing, liquefying equipment, etc., 



