초록 ▼

A storage tank for cryogenic liquids incorporates an ullage vessel that provides for an ullage space. The ullage vessel is in communication through an ullage line to a fill line that provides cryogen to a cryogen space. The junction where the ullage line and fill line meet is of a certain cross-sec

A storage tank for cryogenic liquids incorporates an ullage vessel that provides for an ullage space. The ullage vessel is in communication through an ullage line to a fill line that provides cryogen to a cryogen space. The junction where the ullage line and fill line meet is of a certain cross-sectional area. Downstream of the junction, the fill line is of a greater cross-sectional area than at the junction. This creates a pressure reduction at the junction during filling, which causes a net flow of material from the ullage space over the course of filling. Once the tank is liquid full, causing cryogen to be redirected down the ullage line, the smaller cross-sectional area of the ullage line compared to the fill line causes a reduction in flow of cryogen which is detected by the fill pump causing filling to stop.

대표청구항 ▼

What is claimed is: 1. A cryogenic tank assembly for holding a cryogenic fluid comprising: a. a vessel defining a cryogen space, b. a ullage vessel defining a ullage space, c. a fill conduit comprising i. an inlet for receiving said cryogenic fluid from outside said cryogenic tank assembly, ii. an

What is claimed is: 1. A cryogenic tank assembly for holding a cryogenic fluid comprising: a. a vessel defining a cryogen space, b. a ullage vessel defining a ullage space, c. a fill conduit comprising i. an inlet for receiving said cryogenic fluid from outside said cryogenic tank assembly, ii. an exit within said cryogen space for delivering said cryogenic fluid to said cryogenic space during a course of filling of said cryogenic space, iii. a broad passage defining a broad cross-sectional area, and, iv. a narrow passage defining a narrow cross-sectional area that is smaller than said broad cross-sectional area, wherein said broad passage is downstream from said narrow passage, d. an ullage conduit defining an ullage cross-sectional area that is smaller than said narrow cross-sectional area said ullage conduit comprising: i. an ullage exit into said fill conduit within said narrow passage, and ii. an ullage opening into said ullage space, wherein said cryogenic fluid is restricted from said ullage space during said course of filling. 2. The cryogenic tank assembly claimed in claim 1 wherein said ullage space is substantially empty of said cryogenic liquid upon completion of said course of filling. 3. The cryogenic tank assembly claimed in claim 1 wherein said fill conduit further comprises a slope defining a slope passage between said narrow passage and said broad passage wherein said slope passage expands from said narrow cross-sectional area to said broad cross-sectional area over a distance determined to reduce flow separation within said cryogenic fluid during said course of filling. 4. The cryogenic tank assembly claimed in claim 1 wherein said fill conduit further defines a second broad passage upstream of said narrow passage defining a second broad cross-sectional area greater than said narrow cross-sectional area. 5. The cryogenic tank assembly claimed in claim 3 wherein said ullage vessel is sealed except through said ullage passage. 6. The cryogenic tank assembly claimed in any one of claims 1 through 5 wherein said ullage vessel defines a restrictive drainage opening providing communication between said cryogen space and said ullage space for the purpose of draining said ullage space of said cryogenic liquid prior to said course of filling. 7. A method of filling a cryogenic storage space with a cryogenic fluid while preventing an ullage space at an initial pressure from being filled with said cryogenic fluid, said method comprising: a. delivering said cryogenic fluid to said cryogenic storage space through a fill conduit defining a narrow passage and a broad passage, said broad passage disposed downstream from said narrow passage, b. allowing fluid communication between said narrow passage and said ullage space through an ullage conduit, said ullage conduit defining an ullage exit into said fill conduit at said narrow passage, c. selecting a flow rate for said cryogenic fluid through said fill conduit such that a narrow passage pressure is established at said ullage exit that is lower than said initial pressure while said cryogen space is being filled with said cryogenic fluid, d. stopping flow through said fill conduit when said cryogen space is substantially liquid full. 8. The method claimed in claim 6 wherein a drop in flow rate is detected once said cryogen space is substantially liquid full, said drop in flow rate is due to flow diversion through to said ullage passage that is more restrictive than flow through said narrow passage. 9. The method claimed in claim 7 further comprising draining at least some of said cryogenic liquid from said ullage space prior to delivering said liquid. 10. The method claimed in claim 7 wherein said flow rate is chosen such that said cryogenic fluid is delivered through said fill conduit substantially free of flow separation. 11. A cryogenic tank assembly for holding a cryogenic fluid comprising: a. a vessel defining a cryogen space, b. a ullage vessel defining a ullage space, c. a fill conduit for directing said cryogenic fluid into said cryogen space, said fill conduit comprising i. an inlet for receiving said cryogenic fluid from outside said cryogenic tank assembly, ii. an exit within said cryogen space for delivering said cryogenic fluid to said cryogen space during a course of filling of said cryogenic space, iii. a broad passage defining a broad cross-sectional area, and, iv. a narrow passage defining a narrow cross-sectional area that is smaller than said broad cross-sectional area, wherein said broad passage is downstream from said narrow passage, v. an ullage opening defining an ullage cross-sectional area that is smaller than said narrow cross-sectional area, said ullage opening defining a ullage passage between said narrow passage and said ullage space, wherein said cryogenic fluid is restricted from said ullage space during said course of filling. 12. The cryogenic tank assembly of claim 11 wherein said ullage space is substantially empty of said cryogenic liquid upon completion of said course of filling. 13. The cryogenic tank assembly of claim 11 wherein said fill conduit further comprises a slope defining a slope passage between said narrow passage and said broad passage wherein said slope passage defines a slope cross-sectional area that expands from said narrow cross-sectional area to said broad cross-sectional area over a distance determined to reduce flow separation within said cryogenic fluid during said course of filling. 14. The cryogenic tank assembly of claim 11 wherein said fill conduit further defines a second broad passage upstream of said narrow passage defining a second broad cross-sectional area greater than said narrow cross-sectional area. 15. The cryogenic tank assembly of claims 11 wherein said ullage vessel is sealed except through said ullage passage. 16. The cryogenic tank assembly of claims 11 wherein said ullage vessel defines a restrictive drainage opening providing communication between said cryogen space and said ullage space capable of draining said ullage space of said cryogenic liquid into said cryogen space. 17. A method of filling a cryogenic storage space with a cryogenic fluid while providing for an ullage space for said cryogenic fluid, said method comprising: a. delivering said cryogenic fluid at a flow rate to said cryogenic storage space through a fill conduit, b. during delivery of said cryogenic fluid, establishing a pressure gradient between said fill conduit and said ullage space, said fill conduit and said ullage space being in fluid communication, said pressure gradient resulting in a flow of fluid in said ullage space towards said fill conduit, c. terminating said delivery of said cryogenic fluid through said fill conduit when said cryogen space is substantially liquid full. 18. The method claimed in claim 17 wherein, said delivery of said cryogenic fluid is terminated when a drop in said flow rate is detected. 19. The method of claim 17 wherein said flow rate establishes a venturi between said fill conduit and said ullage space wherein any fluid in said ullage space is drawn to said fill conduit. 20. The method claimed in claim 17 further comprising draining said cryogenic fluid from said ullage space into said cryogen space prior to delivering said cryogenic fluid. 21. The method claimed in claim 17 wherein said flow rate is chosen such that said cryogenic fluid is delivered through said fill conduit substantially free of flow separation.