Continuous analysis of helium in natural gas by chromatography

In extracting helium from natural gas at Bureau of Mines helium plants, a continuous analysis of the helium content of inlet and outlet gas streams is required to determine extraction efficiency. An analyzer, using established principles of gas chromatography to effect the analysis, has been developed to meet this need. It will record the helium content of inlet or discharge gases from helium-extraction plants every five minutes, continuously, without the attendance of an operator. A 25-inch column of activated charcoal is used as a partitioning agent; nitrogen is the carrier gas; and a hot-wire, thermal-conductivity cell is the detector. A 1.0 mv. strip chart indicates the unbalance of the detector cell. Sample size is 0.37 cc. and carrier gas flow rate is 75 cc. per minute. When the instrument was tested in the helium plants, its utility exceeded expectations. Helium analyses from the chromatograph were utilized by operators to modify procedures, thereby effecting significant reductions in helium loss. None of the operators in the three plants in which the instrument was used wanted to release it at the end of the test period. At one plant it is estimated that the reduction in helium loss was equivalent to $100 permore » day in added helium production. A great deal of helium is being saved from loss in the outlet gas streams. Data obtained during the plant tests showed that the improvement in helium recovery may reach 7 million cubic feet per year for all existing helium plants. The value of this helium is about eighty thousand dollars.« less