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Service Life Prediction of Cryogenic Facilities

#3939


Service Life Prediction and Assessment of Current Mechanical Condition of Cryogenic Facilities

Tech Area / Field

  • CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
  • MAT-ALL/High Performance Metals and Alloys/Materials

Status
3 Approved without Funding

Registration date
20.01.2009

Leading Institute
TATA Science and Technical Center, Russia, N. Novgorod reg., Sarov

Collaborators

  • Nanotech Industries, USA, CA, Daily City\nUniversity of Central Florida / Interdisciplinary Studies, USA, MA, Westford\nNissan Motor Co., Ltd., Japan, Tokyo\nUniversity of Miami / Clean Energy Research Institute, USA, FL, Coral Gables\nInstitute of Solid State Physics, Latvia, Riga\nAustin Peay State University, USA, TN, Clarksville\nUniversity of Ontario Institute of Technology, Canada, ON, Oshawa

Project summary

Operation of cryogenic facilities is associated with the problem of their residual service life prediction and assessment of their mechanical condition. Earlier investigations have demonstrated that such an assessment can be performed using a diagnostic vacuum environment.

Accumulated thermomechanical damage of cryogenic facilities results in the loss of tightness and leaks of expensive liquid materials, and accidents (for example, explosions resulting from hydrogen leaks). This makes early prediction of possible loss of tightness of cryogenic tanks, pipelines, etc very important [1].

STC «TATA» Ltd. engineers have practical experience in operating cryogenic facilities and assessing their technical condition [2]. Their investigations have shown that accumulation of fracture is accompanied by the growth of hydrogen content in the diagnostic vacuum environment [3].

Specialists participating in this Project have a great deal of hands-on experience in the analysis and simulation of structural materials’ response to cyclic thermomechanical loads, which generally result in the loss of tightness and fracture of cryogenic facilities. STC «TATA» Ltd. has well-developed research and laboratory facilities.

So far, only the total content of hydrogen in the diagnostic vacuum environment could be measured. Absolute measurements of dynamic hydrogen release from the ‘traps’ in the material into the diagnostic vacuum environment provide evidence on the volume of the “traps” of this type, concentration of the “traps” and binding energy in such “traps”. Thus, one can control the building-up of different defects in structural materials [4-7].

The method being proposed rests upon the concept of determining the degree of porosity of incipient microscopic cracks based on the increment of hydrogen flow from the metal of a working structure into the vacuum space due to the release of hydrogen accumulating in the lattice in the region of an anticipated defect in microscopic voids.

The procedure of crack detection in a cryogenic tank includes emptying the tank, warming it up, heating it to some constant temperature tST, thermostating and evacuating to pressure P0 and further pressure control using a nitrogen trap placed in front of a pressure level gage. Once the pressure levels off, evacuation is stopped, and the heat insulation space is communicated with the space with a thermostated non-pulverized chemical hydrogen absorber. Decrease and leveling of pressure in the heat insulation space to the pressure Р1 is observed and recorded, and the rate of pressure growth is determined. Then, the region with the chemical absorber is separated from the heat insulation space, and further pressure growth to Р0 is observed, the rate of pressure growth is determined, and the function of total hydrogen release versus the time of operation and cycles of the temperature cycled tank is obtained, based on which porosity of the surface facing the heat insulation space is obtained. Once the porosity achieves the permissible level at a number of cycles equal to N0, the remaining permissible number of cycles is determined using the formula:

Nadd = N0 /nN, where nN is the safety margin with respect to the number of cycles.

As a next step of investigations, specific criteria and techniques should be developed to assess the degree of thermomechanical fatigue of a structural material on the basis of measured hydrogen flows from the traps into the diagnostic vacuum space and to predict the service life of cryogenic facilities.

The investigations should include establishing the correlation between the content of hydrogen with different binding energies and the type of mechanical defects that accumulate it.

The investigations proposed will help identify the set of diagnostic tools enabling reliable prediction of the condition of cryogenic facilities by monitoring the diagnostic vacuum environment. The results of such monitoring can be used for well-grounded decision making on the continued use of the facilities, including those, whose warranty service life is over.

The experience gained in the course of diagnosing cryogenic facilities and simulating hydrogen accumulation and fracture will make it possible to develop practical recommendations with respect to the design and building of such facilities such as to increase their warranty service life, which will help considerably reduce operational costs of such facilities in the chemical industry and in hydrogen power engineering [8-10].

References

  1. Gusev A.L. Prediction of hydrogen-caused wall degradation in a large cryogenic temperature cycled tank with a vacuum screen heat insulation and prevention of its fracture (in Rus.). Proceedings of the 2nd International Conference “Hydrogen Treatment of Materials”, June 2-4, 1998, Donetsk.
  2. Gusev A.L. A feasibility study for the implementation of low-temperature recovery of integrated cryoabsorption devices in the heat insulation space of a cryogenic hydrogen tank with displacement cryogenic fluid supply (in Rus.). Proceedings of the 2nd International Conference “Hydrogen Treatment of Materials”, June 2-4, 1998, Donetsk.
  3. Gusev A.L, Garkusha A.P., Kupriyanov V.I., Ktryakovkin V.P., Shvanke D.V. RF Patent # 2109261, A method for crack detection in a cryogenic tank (in Rus.), 1996.
  4. Kumanin V.I., Sokolova M.L., Luneva S.V. Fracture Development in Metal Materials (in Rus.). Metal science and heat treatment of metals, 1995, #4.
  5. Hellan K. Introduction to Fracture Mechanics. M.: “Mir”, 1988.
  6. Kumanin V.I., Kovaleva L.A., Alexeyev S.V. Durability of Metals under Creeping Conditions (in Rus.). M.: “Metallurgy”,1988.
  7. Khismatullin E.R., Korolev E.M., Livshits V.I. et al. High-Pressure Vessels and Pipelines (in Rus.). Reference book. M.: “Mashinostroyeniye”, 1990, pp.179.
  8. Gusev A.L. Electrosorption phenomena in layers of shield-vacuum heat insulation of hydrogen reservoirs. // Альтернативная энергетика и экология - ISJAEE, № 4. 2007.
  9. Nechaev Y. S., Phillipov G.A., Gusev A.L. Veziroglu T.N. On hydrogen micromechanisms plastification and metallic materials brittle behavior \In the connection of safety and standardization problems// ISJAEE 5-2006, p. 81 - 82.
  10. Gusev A.L. Superinsolation theoretical basis: emergency superinsalation cryostats regimes. I Hydrogen and heat effusion initiated unstable stability // ISJAEE 4-2002.


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