Apparatus and method for transferring a fluid from a subcritical gaseous state into a supercritical state

Abstract

The present invention relates to an apparatus for transferring a fluid, particularly CO 2 , from a subcritical gaseous state into a supercritical state, the apparatus comprising a compressor unit, a pump unit, a drive unit and a liquefaction unit, wherein the compressor unit and the pump unit are commonly driven by the drive unit, and wherein the liquefaction unit is provided downstream of the compressor unit and upstream of the pump unit, wherein the compressor unit is configured to compress the fluid from a first subcritical gaseous state to a first predetermined pressure level of a second subcritical gaseous state, wherein the liquefaction unit is configured to reduce the temperature of the compressed fluid in the second subcritical state downstream of the compressor unit to a predetermined temperature level such that the fluid is transferred from the second subcritical gaseous state to a liquid state.

1 . An apparatus for transferring a fluid, particularly CO 2 , from a subcritical gaseous state into a supercritical state,
 the apparatus comprising a compressor unit ( 110 ), a pump unit, a drive unit and a liquefaction unit, wherein the compressor unit and the pump unit are commonly driven by the drive unit, and wherein the liquefaction unit is provided downstream of the compressor unit and upstream of the pump unit,   wherein the compressor unit is configured to compress the fluid from a first subcritical gaseous state to a first predetermined pressure level (P 1 ) of a second subcritical gaseous state,   wherein the liquefaction unit is configured to reduce the temperature of the compressed fluid in the second subcritical gaseous state downstream of the compressor unit to a predetermined temperature level (T 2 ) such that the fluid is transferred from the second subcritical gaseous state to a liquid state, and   wherein the pump unit is configured to compress the fluid in the liquid state downstream of the liquefaction unit to a second predetermined pressure level (P 2 ) such that the fluid is transferred from the liquid state to the supercritical state.   
     
     
         2 . The apparatus according to  claim 1 , wherein the liquefaction unit comprises a cooling unit configured to perform liquefaction of the fluid by means of air and/or cooling water and/or refrigerated water and/or an external refrigeration medium. 
     
     
         3 . The apparatus according to  claim 1 , wherein the liquefaction unit is further configured to perform a process cooling of an external process unit. 
     
     
         4 . The apparatus according to  claim 1 , wherein the liquefaction unit is provided as an open loop refrigerant system comprising a heat exchanging unit and a precooling unit wherein the open loop refrigerant system is configured to extract a portion of the fluid from the compressor unit, to provide this extracted portion of the fluid to the precooling unit in order to precool the extracted portion of the fluid, to provide this precooled extracted portion of the fluid as a refrigerant to the heat exchanging unit, to further provide the compressed fluid in the second subcritical gaseous state downstream of the compressor unit to the heat exchanging unit, to reduce the temperature of the compressed fluid in the second subcritical gaseous state to the predetermined temperature level (T  2 ) by means of the heat exchanging unit, and to return the extracted portion of the fluid downstream of the heat exchanging unit to the compressor unit. 
     
     
         5 . The apparatus according to  claim 1 , wherein the liquefaction unit comprises a hydrocarbon refrigerant unit configured to perform liquefaction of the fluid by means of a hydrocarbon refrigerant, particularly a C3 refrigerant and/or a C4 refrigerant. 
     
     
         6 . The apparatus according to  claim 1 , wherein the liquefaction unit comprises a coldbox. 
     
     
         7 . The apparatus according to  claim 1 , wherein the drive unit is coupled to the compressor unit and the pump unit via a gearbox and/or wherein the drive unit comprises two output shafts ( 141 ′,  142 ′), wherein a first output shaft of the drive unit is coupled with the compressor unit and wherein a second output shaft of the drive unit is coupled with the pump unit. 
     
     
         8 . The apparatus according to  claim 1 , wherein the drive unit is provided as an electric motor, a steam turbine, an expansion turbine, a hydraulic power recovery turbine, a gas turbine or a combination thereof. 
     
     
         9 . The apparatus according to  claim 1 , wherein the compressor unit is configured to perform centrifugal compression of the fluid in multiple stages with interstage cooling and/or wherein the pump unit is provided as a centrifugal pump. 
     
     
         10 . The apparatus according to  claim 1 , wherein the apparatus is provided as a heat recovery unit and configured to use waste heat to heat up the fluid in the supercritical state and expand it to a liquefaction pressure level. 
     
     
         11 . The apparatus according to  claim 1 , wherein the first predetermined pressure level (P 1 ) is in a range between 50 bar and 70 bar, preferably between 55 bar and 65 bar, and/or wherein the predetermined temperature level (T 2 ) is in a range between 10° C. and 30° C., preferably between 15° C. and 25° C., and/or wherein the second predetermined pressure level (P 2 ) lies above 100 bar, preferably above 125 bar, preferably above 150 bar. 
     
     
         12 . The apparatus according to  claim 1 , wherein the fluid is CO 2  or a fluid mixture comprising CO 2 , especially an azeotropic mixture of CO 2  and ethane. 
     
     
         13 . A method for transferring a fluid, particularly CO 2 , from a subcritical gaseous state into a supercritical state using an apparatus according to  claim 1 , comprising:
 compressing the fluid from a first subcritical gaseous state by means of the compressor unit to a first predetermined pressure level (P 1 ) of a second subcritical gaseous state;   reducing the temperature of the compressed fluid in the second subcritical gaseous state by means of the liquefaction unit downstream of the compressor unit to a predetermined temperature level (T 2 ) such that the fluid is transferred from the second subcritical gaseous state to a liquid state; and   compressing the fluid in the liquid state by means of the pump unit downstream of the liquefaction unit to a second predetermined pressure level (P 2 ) such that the fluid is transferred from the liquid state to the supercritical state.   
     
     
         14 . The method according to  claim 13 , wherein the fluid in the first subcritical gaseous state is provided by a separation unit separating a specific component from a fluid mixture of various components. 
     
     
         15 . The method according to  claim 13 , wherein the fluid in the supercritical state is used for long distance transportation, pipeline transportation, storage, Enhanced Oil Recovery, sequestration, or a combination thereof.