Cryogenic storage tank leak detection system

Claim 1

A system for detecting leaks in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (120) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), and means (250) connected to said first supplying means (210) and to said primary insulation space exhausting means (230) for determining any primary flow difference between the total mass flow of said inert gas into and out from said primary insulation space (140) during a period of time, said determining means (250) being further connected to said second supply means (220) and to said secondary insulation space exhausting means (240) for calculating any secondary flow difference between the total mass flow of said inert gas into and out from said secondary insulation space (120) during said period of time, said primary and secondary flow differences being indicative of a leak present in said secondary barrier (130).

Claim 2

A system for detecting leaks in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (120) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), and means (250) connected to said first supplying means (210) and to said primary insulation space exhausting means (230) for determining any primary flow difference between the total mass flow of said inert gas into and out from said primary insulation space (140) during a period of time, said determining means (250) being further connected to said second supply means (220) and to said secondary insulation space exhausting means (240) for calculating any secondary flow difference between the total mass flow of said inert gas into and out from said secondary insulation space (120) during said period of time, said primary and secondary flow differences being indicative of a leak present in said secondary barrier (130).

Claim 8

A system of detecting leaks in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (210) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), means (710) interconnected with said first supplying means (210) for measuring the primary flow of said inert gas into said primary insulation space (140), means (730) interconnected with said primary insulation space exhausting means (230) for measuring the primary flow of said inert gas out from said primary insulation space (140), means (810) interconnected with said second supplying means (220) for measuring the secondary flow of said inert gas into said secondary insulation means (120), means (840) interconnected with said secondary insulation exhaust means (240) for measuring the secondary flow of said inert gas out from said secondary insulation means (120), means for measuring and generating signals proportional to the pressure (P N ) and temperature (T N ) of said inert gas in said storing means, means connected to said primary insulation space exhaust means for measuring and generating signals proportional to the pressure (P P ) and temperature (T P ) of the inert gas therein, means connected to said secondary insulation space for measuring and generating signals proportional to the pressure (P S ) and temperature (T S ) of the inert gas, and means (250) receptive of said primary flow-in, primary flow-out, secondary flow-in, and secondary flow-out measurements, and of said P N , T N , P P , T P , P S and T s signals for determining any differences in said primary and secondary flows, said primary and secondary flow differences being indicative of a leak being present in said secondary barrier (130).

Claim 9

A system of detecting leaks in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (210) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), means (710) interconnected with said first supplying means (210) for measuring the primary flow of said inert gas into said primary insulation space (140), means (730) interconnected with said primary insulation space exhausting means (230) for measuring the primary flow of said inert gas out from said primary insulation space (140), means (810) interconnected with said second supplying means (220) for measuring the secondary flow of said inert gas into said secondary insulation means (120), means (840) interconnected with said secondary insulation exhaust means (240) for measuring the secondary flow of said inert gas out from said secondary insulation means (120), means for measuring and generating signals proportional to the pressure (P N ) and temperature (T N ) of said inert gas in said storing means, means connected to said primary insulation space exhaust means for measuring and generating signals proportional to the pressure (P P ) and temperature (T P ) of the inert gas therein, means connected to said secondary insulation space for measuring and generating signals proportional to the pressure (P S ) and temperature (T S ) of the inert gas, and means (250) receptive of said primary flow-in, primary flow-out, secondary flow-in, and secondary flow-out measurements, and of said P N , T N , P P , T P , P S and T s signals for determining any differences in said primary and secondary flows, said primary and secondary flow differences being indicative of a leak being present in said secondary barrier (130).

Claim 10

A system for detecting leaks in the secondary barrier (130) between the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10), said system comprising: means (200) for storing inert gas, means (210, 220, 230, 240) connected to said storing means (200) for maintaining a first predetermined pressure (P NP ) of inert gas in said primary insulation space (140) and a second predetermined pressure (P NS ) in said secondary insulation space (120), and means (250) connected to said maintaining means (210, 220, 230, 240) for determining the flow of said inert gas into and out from said primary (140) and secondary (120) spaces over a period of time, said determining means (250) being capable of measuring any differences in the flow rates in and the flow rates out of each of said insulation spaces, said differences in flow rates being indicative of a leak in said secondary barrier (130).

Claim 11

A system for detecting leaks in the secondary barrier (130) between the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10), said system comprising: means (200) for storing inert gas, means (210, 220, 230, 240) connected to said storing means (200) for maintaining a first predetermined pressure (P NP ) of inert gas in said primary insulation space (140) and a second predetermined pressure (P NS ) in said secondary insulation space (120), and means (250) connected to said maintaining means (210, 220, 230, 240) for determining the flow of said inert gas into and out from said primary (140) and secondary (120) spaces over a period of time, said determining means (250) being capable of measuring any differences in the flow rates in and the flow rates out of each of said insulation spaces, said differences in flow rates being indicative of a leak in said secondary barrier (130).

Claim 14

A system for detecting leaks in the primary barrier (150), the secondary barrier (130), and the inner hull of the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10) carrying liquified natural gas in a transport ship (20), said system comprising: means (200, 210, 230) interconnected with said primary insulation space (140) for supplying and maintaining an inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), said first predetermined pressure (P NP ) being less than the pressure of said liquified natural gas (P CH .sbsb.4), means (510, 250) in fluid communication with said primary insulation space for monitoring said inert gas therein for the presence of any gas from said liquified natural gas in the cargo tank (10) due to a leak (520) in said primary barrier (150), means (200, 220, 240) interconnected with said secondary insulation space (120) for supplying and maintaining an inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), said second predetermined pressure (P NS ) being less than the said first predetermined pressure (P NP ) and being less than atmospheric pressure (P O ), means (410, 250) in fluid communication with said secondary insulation space (120) for monitoring said inert gas therein for the presence of any oxygen from the atmosphere due to a leak (420) in said inner hull (110), and means (250) interconnected with said primary and secondary insulation spaces (140, 120) for determining the flow of said inert gas, into and out from said primary and secondary spaces (140, 120) over a period of time, said determining means being capable of measuring any differences in the flow rates in and the flow rates out of each of said insulation spaces, said differences in flow rates being indicative of a leak (600) in said secondary barrier (130).

Claim 15

A system for detecting leaks in the primary barrier (150), the secondary barrier (130), and the inner hull of the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10) carrying liquified natural gas in a transport ship (20), said system comprising: means (200, 210, 230) interconnected with said primary insulation space (140) for supplying and maintaining an inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), said first predetermined pressure (P NP ) being less than the pressure of said liquified natural gas (P CH .sbsb.4), means (510, 250) in fluid communication with said primary insulation space for monitoring said inert gas therein for the presence of any gas from said liquified natural gas in the cargo tank (10) due to a leak (520) in said primary barrier (150), means (200, 220, 240) interconnected with said secondary insulation space (120) for supplying and maintaining an inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), said second predetermined pressure (P NS ) being less than the said first predetermined pressure (P NP ) and being less than atmospheric pressure (P O ), means (410, 250) in fluid communication with said secondary insulation space (120) for monitoring said inert gas therein for the presence of any oxygen from the atmosphere due to a leak (420) in said inner hull (110), and means (250) interconnected with said primary and secondary insulation spaces (140, 120) for determining the flow of said inert gas, into and out from said primary and secondary spaces (140, 120) over a period of time, said determining means being capable of measuring any differences in the flow rates in and the flow rates out of each of said insulation spaces, said differences in flow rates being indicative of a leak (600) in said secondary barrier (130).

Claim 16

A system for detecting and approximating the size of leaks in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (120) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), and means (250) connected to said first supplying means (210) and to said primary insulation space exhausting means (230) for determining any primary flow difference between the total mass flow of said inert gas into and out from said primary insulation space (140) during a period of time, said determining means (250) being further connected to said second supply means (220) and to said secondary insulation space exhausting means (240) for calculating any secondary flow difference between the total mass flow of said inert gas into and out from said secondary insulation space (120) during said period of time, said primary and secondary flow differences being indicative of a leak present in said secondary barrier (130) and the size of said leak.

Claim 17

A system for detecting and approximating the size of leaks in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (120) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), and means (250) connected to said first supplying means (210) and to said primary insulation space exhausting means (230) for determining any primary flow difference between the total mass flow of said inert gas into and out from said primary insulation space (140) during a period of time, said determining means (250) being further connected to said second supply means (220) and to said secondary insulation space exhausting means (240) for calculating any secondary flow difference between the total mass flow of said inert gas into and out from said secondary insulation space (120) during said period of time, said primary and secondary flow differences being indicative of a leak present in said secondary barrier (130) and the size of said leak.

Claim 18

A system of detecting and approximating the size of said leak in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (210) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), means (710) interconnected with said first supplying means (210) for measuring the primary flow of said inert gas into said primary insulation space (140), means (730) interconnected with said primary insulation space exhausting means (230) for measuring the primary flow of said inert gas out from said primary insulation space (140), means (810) interconnected with said second supplying means (220) for measuring the secondary flow of said inert gas into said secondary insulation means (120), means (840) interconnected with said secondary insulation exhaust means (240) for measuring the secondary flow of said inert gas out from said secondary insulation means (120), means for measuring and generating signals proportional to the pressure (P N ) and temperature (T N ) of said inert gas in said storing means, means connected to said primary insulation space exhaust means for measuring and generating signals proportional to the pressure (P P ) and temperature (T P ) of the inert gas therein, means connected to said secondary insulation space for measuring and generating signals proportional to the pressure (P S ) and temperature (T S ) of the inert gas, and means (250) receptive of said primary flow-in, primary flow-out, secondary flow-in, and secondary flow-out measurements, and of said P N , T N , P P , T P , P S and T S signals for determining any differences in said primary and secondary flows, said primary and secondary flow differences being indicative of a leak being present in said secondary barrier (130) and the size of said leak.

Claim 19

A system of detecting and approximating the size of said leak in the barrier (130) separating the primary (140) and the secondary (120) insulation spaces disposed around a cryogenic storage tank (10), said system comprising: means (200) for storing an inert gas, first means (210) connected to said storing means (200) and to said primary insulation space (140) for supplying and maintaining said inert gas at a first predetermined pressure (P NP ) in said primary insulation space (140), means (230) connected to said primary insulation space (140) for exhausting said inert gas from said primary insulation space (140) to maintain said first predetermined pressure (P NP ), second means (220) connected to said storing means (200) and to said secondary insulation space (120) for supplying and maintaining said inert gas at a second predetermined pressure (P NS ) in said secondary insulation space (120), means (240) connected to said secondary insulation space (120) for exhausting said inert gas from said secondary insulation space (120) to maintain said secondary predetermined pressure (P NS ), means (710) interconnected with said first supplying means (210) for measuring the primary flow of said inert gas into said primary insulation space (140), means (730) interconnected with said primary insulation space exhausting means (230) for measuring the primary flow of said inert gas out from said primary insulation space (140), means (810) interconnected with said second supplying means (220) for measuring the secondary flow of said inert gas into said secondary insulation means (120), means (840) interconnected with said secondary insulation exhaust means (240) for measuring the secondary flow of said inert gas out from said secondary insulation means (120), means for measuring and generating signals proportional to the pressure (P N ) and temperature (T N ) of said inert gas in said storing means, means connected to said primary insulation space exhaust means for measuring and generating signals proportional to the pressure (P P ) and temperature (T P ) of the inert gas therein, means connected to said secondary insulation space for measuring and generating signals proportional to the pressure (P S ) and temperature (T S ) of the inert gas, and means (250) receptive of said primary flow-in, primary flow-out, secondary flow-in, and secondary flow-out measurements, and of said P N , T N , P P , T P , P S and T S signals for determining any differences in said primary and secondary flows, said primary and secondary flow differences being indicative of a leak being present in said secondary barrier (130) and the size of said leak.

Claim 20

A system for approximating the size of leaks in the secondary barrier (130) between the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10), said system comprising: means (200) for storing inert gas, means (210, 220, 230, 240) connected to said storing means (200) for maintaining a first predetermined pressure (P NP ) of inert gas in said primary insulation space (140) and a second predetermined pressure (P NS ) in said secondary insulation space (120), and means (250) connected to said maintaining means (210, 220, 230, 240) for determining the flow of said inert gas into and out from said primary (140) and secondary (120) spaces over a period of time, said determining means (250) being capable of measuring any differences in the flow rates in and the flow rates out of each of said insulation spaces, said differences in flow rates being indicative of the size of a leak in said secondary barrier (130).

Claim 21

A system for approximating the size of leaks in the secondary barrier (130) between the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10), said system comprising: means (200) for storing inert gas, means (210, 220, 230, 240) connected to said storing means (200) for maintaining a first predetermined pressure (P NP ) of inert gas in said primary insulation space (140) and a second predetermined pressure (P NS ) in said secondary insulation space (120), and means (250) connected to said maintaining means (210, 220, 230, 240) for determining the flow of said inert gas into and out from said primary (140) and secondary (120) spaces over a period of time, said determining means (250) being capable of measuring any differences in the flow rates in and the flow rates out of each of said insulation spaces, said differences in flow rates being indicative of the size of a leak in said secondary barrier (130).

Claim 22

A system of approximating the size of leaks in the secondary barrier (130) between the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10), said system comprising: means (200) for storing inert gas, means (210, 220, 230, 240) connected to said storing means for delivering said inert gas to said primary and secondary insulation spaces (140 and 120), and means (250) connected to said delivering means (210, 220, 230 and 240) for determining the flow of said inert gas into and out from said primary and secondary insulation spaces, said flow rates being indicative of the approximate, first order, size of any leak in said secondary barrier (130).

Claim 23

A system of approximating the size of leaks in the secondary barrier (130) between the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10), said system comprising: means (200) for storing inert gas, means (210, 220, 230, 240) connected to said storing means for delivering said inert gas to said primary and secondary insulation spaces (140 and 120), and means (250) connected to said delivering means (210, 220, 230 and 240) for determining the flow of said inert gas into and out from said primary and secondary insulation spaces, said flow rates being indicative of the approximate, first order, size of any leak in said secondary barrier (130).