Two phase CO.sub.2 storage tank

A system for delivering liquid carbon dioxide, which system comprises

• high pressure insulated tank means for holding liquid CO.sub.2 to a depth of at least about 10 feet,
• upper inlet means for supplying CO.sub.2 to said tank means,
• lower outlet means for delivering liquid CO.sub.2 from said tank means,
• said tank means including upper receptacle means therewithin for holding liquid CO.sub.2,
• means in an upper region within said tank means for condensing CO.sub.2 vapor so that said condensed vapor collects in said receptacle means and so that a pressure of at least about 150 psig is maintained,
• a first heat exchanger,
• means for withdrawing a first stream of liquid CO.sub.2 from said tank means and transferring said withdrawn liquid CO.sub.2 to said first heat exchanger,
• a mechanical refrigeration cooling unit including a refrigerant compressor and a refrigerant condenser,
• first conduit means connecting an outlet from said condenser to said first heat exchanger so that said condensed liquid refrigerant is caused to flow in heat exchange relationship with said withdrawn liquid CO.sub.2 and become subcooled by giving up heat to said liquid CO.sub.2,
• means for returning CO.sub.2 from said first heat exchanger to said tank means at a location above said receptacle means,
• a second heat exchanger,
• second conduit means connecting a liquid refrigerant outlet from said first heat exchanger to said second heat exchanger wherein said subcooled liquid refrigerant is permitted to expand to vapor,
• said second heat exchanger having a refrigerant vapor outlet which is connected to the suction side of said compressor,
• means for withdrawing a second stream of liquid CO.sub.2 from said tank means and delivering it to said second heat exchanger means where it flows in subcooling heat exchange with said expanding subcooled refrigerant, and
• means for returning said subcooled liquid CO.sub.2 second stream from said second heat exchanger to a lower region of said tank means,
• whereby a reservoir of high pressure, subcooled liquid CO.sub.2 can be established in a bottom region of said tank means.

A system for delivering liquid carbon dioxide, which system comprises

• an insulated tank for holding liquid CO.sub.2 to a depth of at least about 6 feet and having a head section above the liquid level,
• upper receptacle means located in said head section above the liquid level,
• inlet means for supplying liquid CO.sub.2 to said upper receptacle means in said tank,
• lower outlet means for delivering liquid CO.sub.2 from said tank,
• means for condensing CO.sub.2 vapor which is present in said head section of said tank to maintain a desired pressure greater than 150 psig therewithin,
• heat exchange means,
• a mechanical refrigeration type cooling unit including a refrigerant compressor and a refrigerant condenser,
• means for withdrawing liquid CO.sub.2 from said tank and delivering it to said heat exchange means,
• means connecting an outlet from said condenser to said heat exchange means so that condensed liquid refrigerant is caused to evaporate and to subcool liquid CO.sub.2 in said heat exchange means,
• vapor return means interconnecting a refrigerant vapor outlet from said heat exchange means and the suction side of said compressor, and
• means for returning subcooled liquid CO.sub.2 from said heat exchange means to a bottom region of said tank means in a manner so that said returning liquid remains in said bottom region of said tank means, whereby a reservoir of high pressure, subcooled liquid CO.sub.2 can be established in said bottom region of said tank means below a thermocline above which an upper region of liquid can exist in equilibrium with CO.sub.2 vapor in said head section, said liquid CO.sub.2 flowing from said upper receptacle means to the upper surface of liquid in said tank without disrupting said thermocline.

A system for delivering either equilibrium or subcooled liquid carbon dioxide for an end use from a single tank, which system comprises

• an insulated tank for holding liquid CO.sub.2 to a depth of at least about 6 feet,
• inlet means for supplying CO.sub.2 to said tank,
• means for condensing CO.sub.2 vapor, which vapor is present in the upper region within said tank, to maintain a desired pressure greater than 150 psig at the top of said tank,
• heat exchange means,
• a mechanical refrigeration type cooling unit including a refrigerant compressor and a refrigerant condenser,
• means for withdrawing liquid CO.sub.2 from said tank including a plurality of connections to exit ports at different vertical levels,
• means for measuring the depth of liquid CO.sub.2 within said tank means,
• control means for selecting said exit port nearest below the upper surface of said liquid to withdraw liquid CO.sub.2 therefrom,
• means for delivering the withdrawn liquid CO.sub.2 either to said heat exchange means or to an end use,
• means connecting an outlet from said condenser to said heat exchange means so that condensed liquid refrigerant is caused to evaporate and to subcool liquid CO.sub.2 in said heat exchange means,
• vapor return means interconnecting a refrigerant vapor outlet of said heat exchange means and the suction side of said compressor,
• means for returning subcooled liquid CO.sub.2 from said heat exchange means to a bottom region of said tank means, whereby a reservoir of high pressure, subcooled liquid CO.sub.2 can be established in a bottom region of said tank means, and
• outlet means near the bottom of said tank for delivering subcooled liquid CO.sub.2 from said tank to an end use.