Process and combined plant for storage and recovery of energy

Abstract

The present invention relates to a process and plant for storage and recovery of energy using a combined plant that comprises a gas treatment unit and an energy generation unit, wherein in a first operating mode, a low-temperature gas liquefaction product is generated from compressed feed gas that is cooled in a heat-exchange system, and using the gas liquefaction product, a storage liquid is provided, and in a second operating mode, using the stored liquid, a low-temperature process liquid is provided that is warmed in the heat-exchange system, obtaining a pressurized fluid that is work-producingly expanded in the energy generation unit.

What we claim is: 
     
         1 . A process for storage and recovery of energy using a combined plant that comprises a gas treatment unit and an energy generation unit, wherein
 in a first operating mode, a low-temperature gas liquefaction product is generated from compressed feed gas that is cooled in a heat-exchange system of the gas treatment unit, and using the gas liquefaction product, a stored liquid is provided,   in a second operating mode, using the stored liquid, a low-temperature process liquid is provided that is warmed in the heat-exchange system, obtaining a pressurized fluid that is work-producingly expanded in the energy generation unit,   the compressed feed gas is cooled in a first heat-exchange unit of the heat-exchange system in the first operating mode in counterflow to a heat-transfer fluid, and the process liquid is warmed in the first heat-exchange unit in the second operating mode in counterflow to the heat-transfer fluid,   the heat-transfer fluid is cooled in the first operating mode at least in part by means of at least two further heat-exchange units of the heat-exchange system that are operated at different temperature levels, and also each having at least one organic coolant, and said heat-transfer fluid is warmed in the second operating mode,   the directions in which the heat-transfer fluid and the feed gas are conducted through the first heat-exchange unit in the first operating mode are opposite to the directions in which the heat-transfer fluid and the process liquid are conducted therethrough in the second operating mode, and   the heat-transfer fluid and the compressed feed gas are conducted, in the first operating mode, in each case at first pressure levels, and the heat-transfer fluid and the process liquid, in the second operating mode, are conducted in each case at second pressure levels through the first heat-exchange unit, wherein the first pressure levels are at least 5 bar above the second pressure levels.   
     
     
         2 . The process according to  claim 1 , in which the heat-transfer fluid used is free from, or low in, oxidizing and combustible components. 
     
     
         3 . The process according to  claim 1 , in which the heat-transfer fluid used is a fluid predominantly containing nitrogen, neon, helium and/or argon. 
     
     
         4 . The process according to  claim 1 , in which an air treatment unit is used as gas treatment unit and in the first operating mode a low-temperature air liquefaction product is generated as gas liquefaction product from compressed feed air as compressed feed gas which is cooled in the heat-exchange system of the air treatment unit. 
     
     
         5 . The process according to any  claim 1 , in which the first pressure levels of the first operating mode are at 50 to 120 bar, and/or the second pressure levels of the second operating mode are at 40 to 60 bar. 
     
     
         6 . The process according to  claim 1 , in which the at least two further heat-exchange units comprise a second heat-exchange unit that is operated with a first organic coolant that is transferred between two storage containers. 
     
     
         7 . The process according to  claim 6 , in which the first organic coolant used is a fluid that contains a halogenated or non-halogenated alkane or alkene, at least one alcohol and/or at least one aromatic. 
     
     
         8 . The process according to  claim 7 , in which the at least two further heat-exchange units comprise a third heat-exchange unit that is operated with a second organic coolant that is transferred between two storage containers and that is further operated with a third organic coolant that is transferred between two storage containers. 
     
     
         9 . The process according to  claim 8 , in which the second organic coolant is warmed in the first operating mode from a first temperature level at −200 to −140° C. to a second temperature level at −100 to −30° C. and in the second operating mode is cooled from the second temperature level to the first temperature level. 
     
     
         10 . The process according to  claim 9 , in which the third organic coolant in the first operating mode is warmed from a third temperature level at −200 to −140° C. to a fourth temperature level at −140 to −60° C. and in the second operating mode is cooled from the fourth temperature level to the third temperature level. 
     
     
         11 . The process according to  claim 10 , in which, in the first operating mode, the second organic coolant at the first temperature level and the third organic coolant at the third temperature level are fed to the second heat-exchange unit, and the second organic coolant at the second temperature level and the third organic coolant at the fourth temperature level are withdrawn therefrom and/or in which, in the second operating mode, the second organic coolant at the second temperature level and the third organic coolant at the fourth temperature level are fed to the second heat-exchange unit, and the second organic coolant at the first temperature level and the third organic coolant at the third temperature level are withdrawn therefrom. 
     
     
         12 . The process according to  claim 8 , in which as the second coolant, and the third organic coolant, an identical fluid is used. 
     
     
         13 . The process according to  claim 8 , in which the second organic coolant and/or the third organic coolant a fluid is used that contains a halogenated or non-halogenated alkane or alkene having at most four carbon atoms. 
     
     
         14 . The process according to  claim 1 , in which a fourth heat-exchange unit is used, by means of which the heat-transfer fluid is in part cooled in the first operating mode and which is operated with a further compressed feed gas that is cold-producingly expanded. 
     
     
         15 . The process according to  claim 9 , in which the second organic coolant is warmed in the first operating mode from a first temperature level −196 to −150° C., to a second temperature level at −60 to −40° C., and in the second operating mode is cooled from the second temperature level to the first temperature level. 
     
     
         16 . The process according to  claim 10 , in which the third organic coolant in the first operating mode is warmed from a third temperature level at −196 to −150° C. to a fourth temperature level at −100 to −60° C., and in the second operating mode is cooled from the fourth temperature level to the third temperature level. 
     
     
         17 . A combined plant for storage and recovery of energy, having a gas treatment unit and an energy generation unit, wherein the combined plant has means which are equipped
 to generate a low-temperature gas liquefaction product, in a first operating mode, from compressed feed gas that is cooled in a heat-exchange system of the gas treatment unit, and using the gas liquefaction product, to provide a stored liquid,   to provide a low-temperature process liquid, using the stored liquid, in a second operating mode, to warm said low-temperature process liquid in the heat-exchange system, obtaining a pressurized fluid, and to work-producingly expand the pressurized fluid in the energy generation unit,   to cool the compressed feed gas in a first heat-exchange unit of the heat-exchange system in the first operating mode in counterflow to a heat-transfer fluid, and to warm the process liquid in the first heat-exchange unit in the second operating mode in counterflow to the heat-transfer fluid,   to cool the heat-transfer fluid in the first operating mode at least in part by means of at least two further heat-exchange units of the heat-exchange system that are operated at different temperatures and also with respectively at least one organic coolant, and to warm said heat-transfer fluid in the second operating mode,   to set the directions in which the heat-transfer fluid and the feed gas are conducted through the first heat-exchange unit in the first operating mode opposite to the directions in which the heat-transfer fluid and the process liquid are conducted therethrough in the second operating mode, and   to conduct the heat-transfer fluid and the compressed feed gas, in the first operating mode, in each case at first pressure levels, and the heat-transfer fluid and the process liquid, in the second operating mode, in each case at second pressure levels through the first heat-exchange unit, wherein the first pressure levels are at least 5 bar above the second pressure levels.