Process of complete cryogenic vaporization of liquefied natural gas

Claim 2

A process of completely vaporizing at a low temperature liquefied natural gas by a first vaporization step at a temperature lower than -110*C until the non-vaporized residue of the liquefied natural gas becomes a predetermined amount higher than a critical percentage with respect to the initial weight of the liquefied natural gas at which critical percentage higher hydrocarbons in the residual liquefied natural gas are frozen-out therefrom, but not higher than a percentage of 8 percent above the critical percentage; separating the residual liquefied natural gas from the first vaporized natural gas; heating the first vaporized natural gas to a temperature from 110* to -40*C; and vaporizing the residual liquefied natural gas by a second vaporization step by introducing it into the conditioned first vaporized natural gas.

Claim 3

A process as claimed in claim 1, wherein the cryogenic vaporization is carried out under normal pressure.

Claim 4

A process as claimed in claim 1, wherein the cryogenic vaporization is carried out under a pressurized condition.

Claim 5

A process as claimed in claim 1, wherein the conditioned temperature of the first vaporized conditioned natural gas is from -100* to -50*C.

Claim 6

A process as claimed in claim 4, wherein the conditioned temperature of the first vaporized natural gas is from -100* to -80*C.

Claim 7

A process for completely vaporizing at a low temperature liquefied natural gas while utilizing said natural gas, in both its liquid and vaporous phases, as a coolant for a substance without mixing said natural gas and said substance, comprising the steps of: exchanging heat between natural gas in the liquid phase and said substance to be cooled whereby sufficient heat is removed from the liquefied natural gas such that the natural gas is in a two-phase liquid-vapor mixture; flowing said two-phase liquid-vapor mixture into a separator; separating the natural gas vapors from the natural gas liquid; heating said natural gas vapors by heat exchange with said substance to be cooled; mixing said liquefied natural gas with said heated natural gas vapors at a controlled rate; vaporizing said liquefied natural gas by heat exchange with said already vaporized natural gas; and further heating said vaporized natural gas bY heat exchange with said substance to be cooled.

Claim 8

A process for completely vaporizing at a low temperature liquefied natural gas while utilizing said natural gas, in both its liquid and vaporous phases, as a coolant for a substance without mixing said natural gas and said substance, comprising the steps of: exchanging heat between natural gas in the liquid phase and said substance to be cooled whereby sufficient heat is removed from the liquefied natural gas such that the natural gas is in a two-phase liquid-vapor mixture; flowing said two-phase liquid-vapor mixture into a separator; separating the natural gas vapors from the natural gas liquid; heating said natural gas vapors by heat exchange with said substance to be cooled; mixing said liquefied natural gas with said heated natural gas vapors at a controlled rate; vaporizing said liquefied natural gas by heat exchange with said already vaporized natural gas; and further heating said vaporized natural gas bY heat exchange with said substance to be cooled.

Claim 9

In an apparatus for completely vaporizing at a low temperature liquefied natural gas while utilizing said natural gas, in both its liquid and vaporous stages, as a coolant, for a substance without mixing said natural gas with said substance, the improvement comprising: first heat exchange means for exchanging heat between liquefied natural gas and a substance to be cooled; heat conduit means for feeding said heated liquefied natural gas into a separator means; separator means for separating liquefied natural gas from vaporous natural gas; sensing means for sensing the liquid level of liquefied natural gas in said separator means; second heat exchange means or exchanging heat between vaporous natural gas and a substance to be cooled; second conduit means for feeding vaporous natural gas from said separator to said second heat exchange means; control means for controlling the liquid level in said separator by discharging residual liquefied natural gas into vaporous natural gas leaving said second heat exchange means; third conduit means in which residual liquefied natural gas fed into said third conduit means is vaporized by vaporous natural gas flowing through said third conduit means such that upon leaving said third conduit means all natural gas is in a vaporous state; third heat exchange means for exchanging heat between said vaporized natural gas leaving said third conduit means and a substance to be cooled; and electrical sensing means for sensing the level of residual liquefied natural gas in said separator and for diverting via by-pass valve means said substance to be cooled around said first heat exchange means such that the rate of vaporization of liquefied natural gas in said first heat exchange means is controlled.

Claim 10

In an apparatus for completely vaporizing at a low temperature liquefied natural gas while utilizing said natural gas, in both its liquid and vaporous stages, as a coolant, for a substance without mixing said natural gas with said substance, the improvement comprising: first heat exchange means for exchanging heat between liquefied natural gas and a substance to be cooled; heat conduit means for feeding said heated liquefied natural gas into a separator means; separator means for separating liquefied natural gas from vaporous natural gas; sensing means for sensing the liquid level of liquefied natural gas in said separator means; second heat exchange means or exchanging heat between vaporous natural gas and a substance to be cooled; second conduit means for feeding vaporous natural gas from said separator to said second heat exchange means; control means for controlling the liquid level in said separator by discharging residual liquefied natural gas into vaporous natural gas leaving said second heat exchange means; third conduit means in which residual liquefied natural gas fed into said third conduit means is vaporized by vaporous natural gas flowing through said third conduit means such that upon leaving said third conduit means all natural gas is in a vaporous state; third heat exchange means for exchanging heat between said vaporized natural gas leaving said third conduit means and a substance to be cooled; and electrical sensing means for sensing the level of residual liquefied natural gas in said separator and for diverting via by-pass valve means said substance to be cooled around said first heat exchange means such that the rate of vaporization of liquefied natural gas in said first heat exchange means is controlled.