Technology
Fermilab starts up helium liquéfier unit Liquid helium from facility
Helium produced by the liquéfier will be used to help cool 1000 dipole and quadrupole magnets to a temperature of -452° F (4.5° Κ). The magnets are parts of a supercon ducting accelerator ring now being built in the 4-mile circular tunnel at Fermilab (C&EN, Feb. 18, page 31). When finished, the new ring will permit the present maximum particle energy of 500 GeV to be doubled and also allow for a new generation of colliding beam experiments. Helium flow in the liquéfier is in a closed loop. Gaseous helium begins the cycle at ambient atmospheric conditions when it enters the compressors. Entry flow rate is 15,000 scfm. There are three stages of compression, with intercooling back to room temperature. The compressed gas is then demisted to remove oil droplets from the compressor lubricant and passed through a bed of activated charcoal, which removes oil and water vapors as well as any other contaminants. The final stage before liquefaction is a particle filter.
will be used to help cool magnets in superconducting accelerator ring now under construction at laboratory The Fermi National Accelerator Laboratory has begun operating its central helium liquéfier facility, roughly doubling world capacity to liquefy helium. The absolute quantity of helium involved may seem rather small to the megaton commercial world, but it would be hard to overestimate the significance of the event to the developing technology of cryogenics. The initial production rate, says project head Ronald Walker, was about 2000 liters per hour. Design capacity of the liquéfier is 4500 liters per hour, but he suggests that it may be possible to exceed that rate.
Helium flows in closed loop in liquéfier facility High-pressure helium from ring
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C&EN June 16, 1980
5000-gal helium storage
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The heart of the liquéfier is the "cold box," a multistory insulated processing vessel, which contains heat exchangers and expanders. There are four stages of cooling in the cold box, the first in a heat exchanger cooled by liquid nitrogen. This is followed by three stages of turboexpansion with refrigeration recycle between the stages. Gas from the final turboexpander finally passes through a valve, undergoing Joule-Thompson expansion, which produces the liquid helium. The helium exiting from the Joule-Thompson valve is about 50% saturated liquid at 1.4 atm and 4.5° K. After vapor-liquid separation, the liquid helium is subcooled and the vapor is recycled. The liquid helium is then available for use in the accelerator ring. Carnot efficiency of the cold box is 22%. Walker says that Fermilab's helium liquéfier is roughly three times as large as the largest known commercial helium liquéfier, operated by Union Carbide's Linde division at Bushton, Kan. Capacity of the Carbide plant is estimated at 300 million scf per year. Any sudden increase in helium consumption usually raises the spectre of a helium shortage. If one develops, Fermilab director Leon Lederman doesn't think research will be to blame. The quantity of helium used in research just isn't big enough to cause any shortage by itself. However, Lederman does speculate that superconductivity could become big business in the future and cause a helium shortage. Probably the most important future use of superconducting systems will be in the generation and transmission of electric power. Cryogenic magnetohydrodynamic generators are being designed, and underground transmission lines using cryogenic cooling are already under development. At Fermilab, interest in cryocooling is restricted to operation of the supercooled magnets to increase the magnetic field intensity of the accelerator equipment. The doubler project will make available particles with maximum energies of 1000 GeV. There is also interest in the possibility of a larger accelerator ring at the Fermilab site. This would have a
potential particle energy of 5000 GeV (5 TeV). Colliding beams from such an accelerator would have a total en ergy of 10 TeV, a prospect that has been known to entrance a particle physicist. However, as entrancing as the prospect may be, Lederman doesn't foresee any 5-TeV accelerators in the near future. The funds aren't avail able at present and the political cli mate isn't favorable for their approval in the next few years. Also, the value of the present facilities must be proved before larger ones can be jus tified. D
agrees that society has perceived only the tip of the iceberg with regard to the risks associated with modern technology (only one fifth of corpo rate executives and financial leaders share this view). A 56% to 39% ma jority of the public also agrees that the overall safety of our society will be jeopardized significantly in the next 20 years unless technological devel opment is restrained, compared with agreement to this statement by only 5 to 6% of corporate executives and lenders. Congress and federal regulators tend to side with the business and fi nancial communities o*n this issue. Three of four members of Congress (74%) and federal regulators (77%) surveyed disagree with the idea that advanced technology must be re strained to assure societal safety. The public is well informed about the Slight majorities of both government risks arising from technology, is con groups also reject the argument that cerned about them, but, on balance, only the tip of the iceberg has been feels that the future benefits to soci perceived regarding technological ety of technology outweigh its risks. risks. This is the optimistic view of the On touchier questions, such as who U.S. public that comes from a survey should be principally responsible for of some 1500 individuals on attitudes ensuring a safe society for the future, toward living with risk in a techno the various groups again view the logical society, conducted by the subject differently. The public names well-known polling organization, most often the individual (42%), then Louis Harris & Associates. government (35%), then the business The survey was commissioned by community (14%) to have this re Marsh & McLennan Cos., an insur sponsibility. Congress and federal ance brokerage firm. It consists of two regulators think the most important parts: one a nationwide telephone role belongs to the government (40% survey of attitudes of the general of members of Congress and 60% of public; and the other, longer, in-per- federal regulators list this first). And son interviews with 600 corporation business and financial leaders, al executives, investors and bankers, though calling the individual princi members of Congress, and members pally responsible most often, are more likely than any other group to lay of federal regulatory agencies. Among the findings is that al chief responsibility for future safety though 55% of the people in the gen on the business community. eral survey think that the risks to so Hardly anyone surveyed is satisfied ciety stemming from scientific and with the job the various federal technological advancements will be agencies are doing at present to make greater 20 years from now than they U.S. society safe. (This question was are today, 68% think that the benefits not asked on the survey of the general also will be greater, and 58% think public.) Only the Food & Drug Ad these benefits will outweigh the ministration and the Civil Aeronau risks. tics Board are rated as either excel On the question of what place reg lent or very good at protecting public ulation has in attempting to control safety by any of the groups ques technological risks, however, strong tioned. The Environmental Protec differences are found in the opinions tion Agency, Occupational Safety & of the different groups surveyed. For Health Administration, Consumer example, 91% of corporate executives Product Safety Commission, and and 90% of financial leaders agree Nuclear Regulatory Commission all that development of advanced tech were viewed most of the time as only nology should continue in as unin fair, whereas the Department of En hibited a regulatory environment as ergy was most often thought to do a possible. And 88% of corporate exec poor job in this area. Congress' Office utives and 84% of the financial com of Technology Assessment, which was munity think that incidents such as rated fair-to-good by members of Three Mile Island and Love Canal Congress, seems largely unknown in have exaggerated the risks associated the business and financial com munities, where 62% and 70%, re with advanced technology. The public, however, sees it dif spectively, said they were not sure D ferently. A 62% to 28% majority how good a job it did.
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Public says technology benefits outweigh risks
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June 16, 1980 C&EN
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