A process for producing liquid carbon dioxide. A process stream which
comprises carbon dioxide, balance substantially nitrogen and water, is
cooled so that a minor amount of the water is condensed out. The process
stream is compressed so that substantially all of the water but trace
amounts is condensed out. Next, the process stream is cleaned to remove
the trace amounts of water, any long-chain hydrocarbons present and any
particulates present. The process stream is then separated into a
nitrogen-rich gaseous stream and a carbon dioxide-rich gaseous stream. The
carbon dioxide-rich gaseous stream is then compressed and the
nitrogen-rich gaseous stream is expanded to produce an expanded
nitrogen-rich gaseous stream. The energy of the expanding is used to
compress the carbon dioxide-rich gaseous stream. The compressed carbon
dioxide-rich gaseous stream is cooled to liquefy the carbon dioxide in the
stream and reduce the temperature of the gaseous nitrogen in the stream.
The liquefied carbon dioxide is withdrawn as product. The liquefying of
the carbon dioxide-rich gaseous stream is by using the expanded
nitrogen-rich gaseous stream. After the liquefying, the nitrogen-rich
gaseous stream is used to perform at least part of the first cooling. In a
preferred form, the process stream results from combusting a mixture of
fuel and oxygen in a heat engine to drive an electrical generator with the
product of the heat engine to produce electricity and also yielding the
process stream. Apparatus for the production of liquid carbon dioxide
which includes devices to perform each of the process steps.
