Process and apparatus for producing liquid carbon dioxide

Abstract

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 The liquefied carbon dioxide is withdrawn as product.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.