PROCESS AND APPARATUS FOR EXTRACTING LIQUID CO2 FROM A SOLID CO2 STORAGE
Publication Date: 2015-May-28
The IP.com Prior Art Database
FROM A SOLID CO2 STORAGE
The present invention relates to a process for extracting liquid carbon dioxide from solid carbon dioxide stored in a storage tank.
It is frequently desirable to store liquid rich in carbon dioxide, a liquid rich in carbon dioxide being defined as containing at least 30% carbon dioxide, preferably at least 60% carbon dioxide.
For example, in the case of a network extracting gas rich in carbon dioxide from various sources wherein the gas is liquefied and then supplied to a consumer, the consumer may have varying requirements and may not require all the liquid rich in carbon dioxide all the time.
It is expensive to store the gas rich in carbon dioxide under pressure and the size of the storage vessels is limited.
Furthermore, solid storage presents many advantages, notably reduced heat leaks and potential for energy savings.
However, solid CO2 can’t be easily used and needs to be melted in order to be released from its storage. Thus a mixture of solid and liquid is formed in the vessel. The present invention provides a practical way to extract liquid only from the CO2 stored in a storage tank.
Existing Solutions, Their Drawbacks and Limits
If solid CO2 is melted into a storage tank by gas injection, it first forms a mixture of solid and liquid (slurry, or slush) and it might not be possible to evacuate the slurry without the solid, or even to evacuate liquid at all. US patent # 4765143 presents a way to evacuate slush into a separate vessel where a horizontal screen is filtering the solid out of the slush in order to evacuate only the liquid. However this method raises several concerns:
· Pressure drops: the filtering of solid might create pressure drops. However at the pressure of the vessel (i. e. very close to triple point pressure), any pressure drop might form additional solid and block the filtering screen.
· Circulation of the slush: in order to be able to move the slush from a first vessel to a second vessel the viscosity of such slush needs to be relatively low. This might mean alm...