Transportation and Storage of

The cost of pipeline transportation of hydrogen is higher (20-30%) than that for natural gas for equivalent energy flow. Another major difference is due to the small molecular size of H2 (diameter = 0.289 nm) compared to CH4 (diameter = 0.38 nm). Hence, H2 pipelines are more susceptible to 

The storage of hydrogerras, a liquid (LH2), is well known in the nuclear field where the liquid hydrogen bubble chamber (5-1,500 L) is used to detect nuclear particles. Liquid hydrogen is also used as a fuel. 

The hydrogen molecule exists in two forms ortho-H2 and para-H2. In ortho-H2, the nuclear (proton) spins of the two hydrogen atoms are parallel, whereas in para-H2, the nuclear spins are antiparallel. It is possible to catalytically convert hydrogen to the pure lower energy P-H2 at low temperatures (T 20 K), but at higher temperatures (T 200 K), only an equiUhrium mixture of 25% P-H2 and 75% 0-H2 can be obtained. The conversion of 0-H2 to P-H2 is an exothermic process which at 10 K, A// = -1.062 kJ/mol and at 300 K, = 55.5 J/mol. 

The liquefaction of hydrogen produces 25% P-H2 + 75% 0-H2, and the slow conversion of 0-H2 to P-H2 adds an additional heat source to the storage system. Hence, it is desirable to cmivert the 0-H2 to P-H2 either completely in the liquid state (by adding charcoal) or preferably partially in the precooled gas phase (at 77°K, liquid N2, the equilibrium mixture of H2 vapor, is 60% P-H2) followed by complete conversion in the liquid state. This reduces the losses on storage from 25%/day for 25% P-H2 to 0.02%/day for 98% P-H2. 

Liquid hydrogen, like liquid helium, is usually stored in double Dewar flasks, an outer Dewar containing liquid nitrogen (b.p. = 77 K) into which is placed the second Dewar containing the liquid hydrogen (b.p. 20.3 K). However, in transport by truck or rail, single horizontal cylindrical Dewars are used with multilayer insulation, resulting in typical boil-off losses of 0.25%/day. 

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Liquefied natural gas (LNG) also plays a large role in both the transportation and storage of natural gas. At a pressure of 101.3 kPa (1 atm), methane can be Hquefted by reducing the temperature to about — 161°C. When in the Hquid form, methane occupies approximately 1/600 of the space occupied by gaseous methane at normal temperature and pressure. In spite of the very low temperature of the Hquid, LNG offers advantages for both shipping and storing natural gas. 

In addition to encompassing all of the unit operations in the plant, the plant flow sheets may also include materials handling operations associated with the transport and storage of materials in and around the mill. Typically, flow sheets provide quantitative information regarding water and slurry flows, toimages, and assays. 

The NRC has developed special procedures for the handling, transportation, and storage of nuclear fuel because radioactivity can be a health hazard if not properly shielded. Spent fuel is typically transported by rail or tmck in heavily shielded (Type B), sealed, thick metal shipping containers designed to withstand possible accidents, such as derailments or coHisions, which may occur during transport. The NRC certifies that each shipping container meets federal requirements. The U.S. Department of Transportation sets the rules for transportation. 

George W. Gassman, Paul J. Schajhuch, Thomas J. McAvoy, Dale E. Seborg Process Economics F. A. Holland, J. K Wilkinson Transport and Storage of Fluids Meherwan P. Boyce Heat-Transfer Equipment Richard L. Shilling, Kenneth J. Bell,... 

Meherwan P. Boyce, P.E., Ph.D., President, Boyce Engineering International ASME Fellow Registered Professional Engineer (Texas, Oklalioma) (Section 10, Transport and Storage of Fluids Section 29, Process Macliinery Drives)... 

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