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US-12618515-B2 - Organic composite gas storage tank

US12618515B2US 12618515 B2US12618515 B2US 12618515B2US-12618515-B2

Abstract

An organic composite gas storage tank 100 comprises a hollow central portion 106 which is substantially cylindrical and formed integrally with first and second end portions 102, 104 , and which defines a longitudinal tank axis 101 . The first end portion 102 comprises a hollow truncated conical region 102 A which meets the hollow central portion at a first end thereof, and a cylindrical region 102 B which meets an end of the hollow truncated conical portion remote from the hollow central portion. An organic fibre winding 107 extends at least between axial positions which coincide with the hollow truncated conical region of the first end portion and the hollow central portion respectively. A hollow metal end-fitting 120 has a hollow truncated conical portion 124 embedded within the wall of the hollow truncated conical region of the first end portion, providing a long leakage path around the metal end-fitting.

Inventors

  • Eric W Dean

Assignees

  • ROLLS-ROYCE PLC

Dates

Publication Date
20260505
Application Date
20230523
Priority Date
20201013

Claims (12)

  1. 1 . An organic composite gas storage tank comprising a hollow central portion formed integrally with first and second end portions and which defines a longitudinal tank axis, the first end portion comprising: (a) a hollow truncated conical region comprised of a wall of a single internal wall material which meets the hollow central portion at a first end thereof, the outer and inner radii of the hollow truncated conical region decreasing in a direction along the longitudinal tank axis away from the hollow central portion; and (b) a cylindrical region which meets an end of the hollow truncated conical region remote from the hollow central portion of the tank, wherein the tank further comprises: (i) a hollow metal end-fitting having a hollow cylindrical portion and a hollow truncated conical portion extending from the hollow cylindrical portion towards the hollow central portion of the tank, the radially outer surface of the hollow cylindrical portion being in contact with the radially inner surface of the cylindrical region of the first end portion, and the radially inner surface of the hollow cylindrical portion being at least in part in contact with stored gas in use of the tank, the hollow truncated conical portion of the metal end-fitting being embedded within the single internal wall material of the wall of the hollow truncated conical region of the first end portion such that both radially outer and radially inner surfaces of the hollow truncated conical portion of the metal end-fitting contact the single internal wall material of the wall of the hollow truncated conical region of the first end portion, the first end portion of the tank and the metal end-fitting forming a single continuous leakage path of the tank from the interior to the exterior thereof by (a) contact of the hollow truncated conical portion of the metal end-fitting with internal material of the wall of the hollow truncated conical region of the first end portion and (b) contact of the radially outer surface of the hollow cylindrical portion of the metal end-fitting with the radially inner surface of the cylindrical region of the first end portion; and (ii) an organic fiber winding extending at least between first and second positions along the length of the tank which coincide with the hollow truncated conical region of the first end portion and the hollow cylindrical portion respectively, the organic fiber winding having windings in planes which are inclined to the longitudinal tank axis.
  2. 2 . An organic composite gas storage tank according to claim 1 wherein the hollow truncated conical region of the first end portion has a wall thickness, defined at a given position along the longitudinal tank axis by the difference between the outer and inner radii of the tank at that position, which decreases in a direction along the longitudinal tank axis away from the hollow central portion.
  3. 3 . An organic composite gas storage tank according to claim 1 wherein the hollow central portion comprises first and second hollow truncated conical portions, the external radius of each hollow truncated conical portion of the hollow central portion decreasing in a direction towards a corresponding end portion, and wherein the tank comprises an organic composite fiber winding extending along the length of the tank over the first and second hollow truncated conical portions of the hollow central portion, the organic composite fiber winding having windings in planes which are inclined to the longitudinal tank axis.
  4. 4 . An organic composite gas storage tank according to claim 1 further comprising a polymer liner in contact with an internal surface of the tank.
  5. 5 . An organic composite gas storage tank according to claim 1 wherein the hollow truncated conical region of the first end portion has a semi-vertical angle less than or equal to 45°.
  6. 6 . An organic composite gas storage tank according to claim 1 wherein a ratio of a length of the hollow central portion to a maximum external diameter of the hollow central portion is at least 10.
  7. 7 . An organic composite gas storage tank according to claim 1 wherein a ratio of a length of the hollow central portion to a maximum external diameter of the hollow central portion is at least at least 20.
  8. 8 . An organic composite gas storage tank according to claim 1 wherein a ratio of a length of the hollow central portion to a maximum external diameter of the hollow central portion is at least 50.
  9. 9 . An organic composite gas storage tank according to claim 1 wherein the tank comprises a laminate material.
  10. 10 . An organic composite gas storage tank according to claim 1 wherein loops of the organic fiber winding are inclined to the longitudinal tank axis at an angle between 45° and 60°.
  11. 11 . An organic composite gas storage tank according to claim 1 wherein the hollow central portion is cylindrical.
  12. 12 . An organic composite gas storage tank according to claim 1 wherein no portion of the hollow cylindrical portion of the metal end-fitting extends towards the hollow central portion of the tank past a point where the hollow cylindrical portion of the metal end-fitting joins the hollow truncated conical portion.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS This application is a continuation application of U.S. application Ser. No. 17/450,519 filed Oct. 11, 2021, which in turn claims priority pursuant to 35 U.S.C. 119(a) to United Kingdom Patent Application No. 2016223.6, filed on Oct. 13, 2020. These prior applications are each incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION Technical Field The present disclosure relates to gas storage tanks, particularly gas storage tanks for storing gas under high pressure, for example 500 bar or more, with high gravimetric efficiency. Description of Related Art Storage of gas within a storage tank at high gravimetric efficiency is a desirable technical goal in a number of applications. In the case of static storage of a gas within a gas storage tank, a high gravimetric efficiency corresponds to a relatively low tank mass per unit mass of stored gas (and hence efficient use of tank material) and tends to minimise the energy required to transport a unit mass of stored gas within the tank. Storage of gaseous hydrogen within storage tanks at high gravimetric efficiency and low absolute mass is particularly important in transport applications, especially aeronautical applications, for example where motive power is provided by hydrogen fuel cells (typically polymer electrolyte membrane (PEM) fuel cells) fueled by gaseous hydrogen stored in one or more storage tanks, or by combustion of hydrogen. Organic composite tanks are frequently used in automotive applications due to their low mass, capability to withstand high pressure (several hundred bar) and hence potential for achieving storage of gaseous hydrogen at high gravimetric efficiency. FIG. 10 shows an organic composite tank 400 of the prior art. The tank 400 comprises a hollow cylindrical central section 406 formed integrally with two hollow hemispherical end portions 402, 404. Hoop strength is provided to the hollow cylindrical central section 406 by a helical hoop winding 421 comprising organic fibre, the planes of individual windings being perpendicular to the longitudinal axis of the hollow cylindrical central portion 406. Axial strength is provided to the hollow cylindrical central section 406 by second, high-angle, helical windings 423A, 423B of organic fibre, the planes of individual windings being inclined at around +/−50° to the longitudinal axis of the tank 400. Low-angle windings 425A, 425B add strength to the hemispherical end portions 402, 404, the planes of individual windings of the low-angle windings 425A, 425B being inclined at a small angle to the longitudinal axis of the cylindrical section 406. In order to increase the maximum pressure at which gas (e.g. gaseous hydrogen) can be stored in the tank 400 beyond around 700 bar, typically the wall thickness of the hemispherical end portions 402, 404 is increased, thus increasing the mass of the tank 400. Additionally or alternatively, further low-angle windings such as 425A, 425B may be applied to the tank 400, however there are practical limitations to the number of low-angle windings which can be applied. Further low-angle windings also add weight to the tank 400. The potential for increasing the maximum pressure of stored gas within the tank 400 without adversely impacting its gravimetric efficiency is therefore limited in the case of the tank 400 which is based on a standard configuration comprising a cylindrical central portion and hemispherical end portions. BRIEF SUMMARY According to an example, an organic composite gas storage tank comprises a hollow central portion which is substantially cylindrical and formed integrally with first and second end portions and which defines a longitudinal tank axis, the first end portion comprising (a) a hollow truncated conical region which meets the hollow central portion at a first end thereof, the outer and inner radii of the hollow truncated conical region decreasing in a direction along the longitudinal tank axis away from the hollow central portion; and (b) a cylindrical region which meets an end of the hollow truncated conical portion remote from the hollow central portion of the tank, wherein the tank further comprises (i) a hollow metal end-fitting having a hollow cylindrical portion the outer surface of which is in contact with the inner surface of the cylindrical region of the first end portion, and a hollow truncated conical portion extending from the hollow cylindrical portion towards the hollow central portion of the tank, the hollow truncated conical portion of the metal end-fitting being embedded within the wall of the hollow truncated conical region of the first end portion; and (ii) an organic fibre winding extending at least between first and second positions along the length of the tank which coincide with the hollow truncated conical region of the first end portion and the hollow cylindrical portion respectively, the organic fibre winding having windings in planes which a