Patent Publication Number: US-11397049-B2

Title: High pressure recovery of carbon dioxide from a fermentation process

Description:
RELATED APPLICATIONS 
     This application is a continuation of and claims priority to U.S. patent application Ser. No. 13/807,138 filed on Feb. 14, 2013, which is a national stage entry of PCT/DK2011/050258 filed on Jul. 1, 2011, which claims priority to Danish Application No. PA201070314 filed on Jul. 2, 2010, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The present invention relates to a method for recovering carbon dioxide from a gaseous stream originating form a fermentation process or a bottling line, by compression, absorption, condensation, and distillation, wherein the method is performed under high pressure. 
     BACKGROUND 
     A preferred way of carbonating beverages, such as brewed products, is by purifying carbon dioxide on site. Therefore, carbon dioxide streams originating from a fermentation process, such as in a brewery, are often purified and returned to the brewery. Thus, the carbon dioxide generated by the fermentation process is used again in the brewed drink or other carbonated beverages produced at the same site as the fermentation process, is used as a so-called cover gas in the bottlery to prevent entrainment of air or to displace air. 
     Presently the most commonly used method comprises the steps of: defoaming; washing in a water scrubber; compressing; filtrating through a carbon filter; dehydrating; reboiling and distilling the carbon dioxide stream in order to provide the purified carbon dioxide stream. This method effectively purifies carbon dioxide with a satisfactory yield and purity, but several elements of the process add to the cost of the overall recovery process. First of all, the water used in the water scrubber must be disposed of, moreover the carbon filters and dehydrators must be regenerated routinely, and finally external power must be supplied to the method. The large amount of unit operations in the method requires means for maintaining the pressure over the entire system. Generally, the more unit operations comprised in a system the larger the pressure drop and hence the costs for maintaining the same. 
     Moreover, the conventional final liquefaction of carbon dioxide requires substantive energy supply. The condensation is typically performed by an ammonia cooled condenser. Also, the liquid carbon dioxide produced must be stored in a storage tank and has to be re-evaporated before being used as cover gas or as carbon dioxide for carbonating the beverages. In the conventional method the system is operated at a pressure of approximately 16 bar corresponding to the pressure of a standard carbon dioxide storage tank in which liquid carbon dioxide is stored before being used. 
     Operating at—in this context—low pressure is the conventional way in the field for recovering high purity carbon dioxide in food grade quality, mainly because this has been considered most economical for several reasons, such as the purity obtained and the cost of installation. 
     However, operating at lower pressures requires a very high degree of water removal, as the presence of water in the system will cause problems with the formation of ice or gas hydrates. In addition, condensation of the purified carbon dioxide to provide liquefied carbon dioxide requires a high energy input. 
     The issue of condensation has been addressed in EP 0194795 A2 wherein a recovery process is described in which impure carbon dioxide from a brewing plant is pressurized and cooled, producing a substantially pure carbon dioxide liquid stream and a stream of gaseous impurities, i.e. non-condensable gases. This is followed by expansion of the pure carbon dioxide liquid stream to provide a liquid and gaseous pure carbon dioxide stream, whereby the liquid carbon dioxide provided is used to liquefy the gaseous stream of the initial compression step. Thus, this method provides a solution in which cooling and liquefaction of carbon dioxide is effected by the expansion and evaporation of substantially pure liquid carbon dioxide. Thereby, internal heat transfer and/or cooling power is utilized to supply energy for a purification step. It is stated that this process reduces the specific and overall power consumption and the heat required for vaporization. However, only when the liquefied carbon dioxide is fully employed and expanded will the method be fully economical. Therefore, this method still requires a large energy input for the condensing of the carbon dioxide. The present invention is a method in which one or more of the above problems of the prior art have been solved. 
     SUMMARY 
     Some embodiments provide a method for recovering carbon dioxide from a gaseous carbon dioxide stream originating from a fermentation process, brewery or a bottling line. The method comprises the steps of a) providing the carbon dioxide stream originating from the fermentation process, brewery or bottling line and b) compressing the provided carbon dioxide stream by at least one compression step providing a compressed gaseous stream. The method also comprises a step c) of subjecting the compressed gaseous stream to an absorption step providing at least a carbon dioxide rich gaseous stream, a step d) of condensing the carbon dioxide rich gaseous stream in a condenser providing at least a condensate and a purge gas, and a step e) of distilling the condensate to provide purified carbon dioxide. Further, the pressure of the compressed gaseous stream obtained in step b) is at least 30 bar, the temperature is within a range where there is substantially no condensation of carbon dioxide and whereby the pressure of the compressed gas stream is maintained to at least step d). 
     In further embodiments, the absorbent of step c) is selected from the group consisting of water and liquid carbon dioxide. The method may also include further processing that is selected from one or more of: transferring as a product to a beverage production plant, condensing and transferring to a storage tank, and feeding to the compression step b) or the distillation step e). In addition, the condensed, distilled carbon dioxide may be re-evaporated by a coolant before the condensing step d). 
     In some embodiments, the condensation of step d) is performed by a coolant used in the brewery, fermentation process or bottling line, and the coolant may comprise a brine. In particular embodiments, the brine is an aqueous mixture which lowers a freezing point of water. 
     Further, in some embodiments, the at least one compression step is performed by means of an oil lubricated screw compressor. The compressed gaseous stream may also be filtered before the condensation of step d) by means of a mechanical and/or adsorption filter. In some embodiments, the pressure is reduced after the condensing step d) and the distillation of step e) is performed at the reduced pressure. 
     Further embodiments of the method comprise a step f) of subjecting the purge gas obtained in step d) to a combined condensing and re-evaporation step, wherein the re-evaporation step is performed at a lower pressure than the pressure of the purge gas obtained in step d). In addition, the carbon dioxide obtained may be re-evaporated to provide a gaseous carbon dioxide stream for use in a production in need of gaseous carbon dioxide. The method may also comprise a step f) of providing liquid carbon dioxide from the distillation unit of step e) or from the condensation of step d) and a step g) of evaporating the liquid carbon dioxide in a heat exchanging means to provide a gaseous heated carbon dioxide steam. Further, the method may comprise a step h) of expanding the gaseous heated carbon dioxide stream to provide an expanded gaseous heated carbon dioxide stream and a step i) of heating the expanded gaseous heated carbon dioxide stream to provide a gaseous carbon dioxide stream for use in a production in need of gaseous carbon dioxide. 
     Some additional embodiments provide a purification process for recovering carbon dioxide from a gaseous carbon dioxide stream originating from a fermentation process, brewery, or a bottling line. The purification process may comprise an absorber providing a carbon dioxide rich gaseous stream and a contaminant rich stream, and a distillation column providing a purified carbon dioxide stream. Further, at least a fraction of the purified carbon dioxide stream is recycled to the absorber for use as an absorbent therein. 
     The purification process may further comprise a compressor and a condenser. In particular embodiments, the carbon dioxide rich gaseous stream is an inlet to the condenser and the condenser provides at least a condensate and a purge gas. Further, the condensate may be an inlet to the distillation column and the distillation column may further provide a second purge gas. 
     In some embodiments, the compressor compresses a carbon dioxide stream to a pressure of at least 30 bar to provide a compressed gaseous stream. The compressed gaseous stream may also be an inlet to the absorber and, in particular embodiments, the pressure may be maintained above 30 bar to at least the condenser. The purification process may also include a reboiler. In further embodiments, the compressed gaseous stream evaporates a fraction of the purified carbon dioxide stream in the reboiler. 
     A purification system for recovering carbon dioxide from a gaseous carbon dioxide stream originating from a fermentation process, brewery or a bottling line is provided. The purification system includes a compressor in fluid communication with an absorber. The compressor provides a compressed gaseous stream at a predetermined pressure and the absorber separates the compressed gaseous stream into a carbon dioxide rich gaseous stream and a contaminant rich stream. A condenser is designed to operate at a pressure of at least 30 bar and is designed to separate the carbon dioxide rich gaseous stream into a condensate and a purge gas. A distillation column is configured to separate the condensate into a second purge gas and a purified carbon dioxide stream. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a detailed overview of an embodiment of the process according to the invention. 
         FIG. 2  is a detailed overview of an embodiment of the process according to the invention. 
         FIG. 3  is a simplified schematic overview of the embodiments of  FIGS. 1 and 2 . 
         FIG. 4  is a partial view of a process according to the invention wherein distillation is performed under high pressure. 
         FIG. 5  is a partial view of a process according to the invention wherein distillation is performed under industry standard pressure. 
         FIG. 6  is a particular embodiment for re-evaporating liquid carbon dioxide. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of embodiments of the invention. 
     For illustrative purposes the components and streams referred to in the detailed description of the invention and the drawings are summarized below. 
     Foam trap A 0 ; first, second and third compressors A 1 _ 1 , A 1 _ 2 , A 1 _ 3 ; separator A 2 ; purification unit/absorber A 3 ; condenser A 4 ; distillation unit A 5 ; separator A 6 ; storage tank A 7 ; reboiler A 8 ; filter A 9 ; carbon dioxide scrub reboilers A 10  and A 10 _ 1 ; sub-cooler A 11 ; second sub-cooler A 1   1 _ 1 ; second reboiler A 1   2 ; second condenser A 1   3 ; valve A 1   4 ; first heat exchanging means A 1   5 ; expander A 1   6 ; second heat exchanging means A 1   7 , and heat exchanging means A 1   8 . 
     The streams shown in the figures and described below are the following: 
     Fermentation gas  101 ; defoamed gaseous stream  102 ; first, second and third compressed gaseous streams  103 ,  104 ,  106 ; compressed reboiled gas  107 ; carbon dioxide rich/contaminant lean gaseous stream  108 ; filtered stream  109 ; purge gas  110 ; absorbent stream  111 ; condensate  111 _ 1 ; condensed sub-cooled stream  111 _ 2 ; cool sub-cooled high pressure  111 _ 3 ; depressurized stream  111 _ 4 ; purified carbon dioxide  111 _ 5 ; cooler stream  111 _ 5 _ 1 ; product stream  111 _ 5 _ 2 ; re-evaporated stream  111 _ 6 ; liquid carbon dioxide from the distillation column/liquefied carbon dioxide  112 ; fraction of liquefied carbon dioxide stream  112 _ 1 ; evaporated carbon dioxide  112 _ 2 ; flash gas  113 ; depressurized liquid  114 ; stored product stream  116 ; heated product stream  117 ; final purge stream  118 ; expanded product stream  119 ; gaseous carbon dioxide stream  120 ; condensed impurities  203 ; waste contaminant rich stream  204 ; waste contaminant rich stream  206 ; reboiled gaseous stream  207 ; scrubber liquid carbon dioxide stream  208 ; coolant  301 , 401 ; warm coolant  302 ,  501 ; and cooled coolant  402 . 
     Further streams are present in  FIG. 1 . The nature of these streams will be readily known by the skilled person and need not further detailing. 
     Now referring to  FIGS. 1 and 3  the invention will be described in more details. 
     The starting gas in the method is a fermentation gas  101  which may be defoamed in a foam trap A 0  before being further processed. Defoaming is optional and the necessity depends on the nature of the incoming gas, for example the operation of the fermenters. The defoamed gaseous stream  102  is subjected to a first compression step in the first compressor A 1 _ 1 . The number of compression steps may be any number from 1 and above. The cost of operation decreases with the number of compressors; however this should be balanced with the cost of acquiring the compressors. In this context the most economical number is three, as embodied in  FIGS. 1 and 3 . The compression step provides compressed gaseous streams  103 ,  104  and  106 , respectively. In between the compressors the stream may be subjected to heat exchange where appropriate. 
     In the embodiment shown a separator A 2  is inserted before the third compressor A 1 _ 3 . This serves to remove condensed impurities  203  primarily water, from the carbon dioxide gas. In general, a separator may be inserted between any of the compression steps, it is within the skill of the art to determine where it will be necessary. The compressed gas  106  is in the embodiment shown routed to a reboiler A 8 , before entering the purification column A 3 . Referring to  FIG. 1  the hot gaseous stream  106  is then used to evaporate a fraction of the liquefied carbon dioxide stream  112 _ 1  from the distillation column A 5  to give evaporated carbon dioxide  112 _ 2 , hence facilitating the distillation process. Other energy sources can be used as well. 
     As previously mentioned due to the difference in pressure between the process and the storage tank, approximately 15-30% of the liquid carbon dioxide will at some point form a flash gas. This flash gas can be used in the distillation column instead of gas generated by for example the reboiler A 8 . 
     The at least one compressor A 1 _ 1  etc. used may be any suitable compressor. It is preferred that at least one compressor is lubricated, more particularly an oil lubricated screw compressor as this will save on capital and operational costs. When such a compressor is used it is preferred that a filter (not shown) is used before the absorption step, particularly when the absorbent used in the absorption step c) is water. When carbon dioxide is the absorbent,  111 , as shown in the embodiment of i.a.  FIG. 1 , oil residues will be removed, and the presence of a filter will serve as an extra precaution as well as a means for recovery and recycling of the oil to the compressors. 
     The compressed reboiled gas  107  enters the absorption column A 3 , preferably in the bottom section thereof. The purification column shown is a carbon dioxide scrubber which is also disclosed in co-pending patent applications WO2009/127217 and PCT/DK2010/050146 hereby incorporated by reference. Thus, the absorption column system comprises in the embodiment shown a scrubber A 3  and an optional CO2 scrub reboiler A 10 . The reboiler A 10  serves to minimize the waste contaminant rich stream  204  by re-boiling the scrubber liquid carbon dioxide streams  208  and  206  to provide the reboiled gaseous stream  207  which is purified again in the column. 
     The absorbent in the purification column is liquid carbon dioxide, preferably drawn from the process further downstream. In the illustrated embodiment the absorbent is the stream  111  taken after the final distillation before depressurization. 
     It is also contemplated that the carbon dioxide scrubber may be improved according to the solution provided in PCT/DK2010/050146 in which the compressed feed stream is purified in a purification column providing at least a contaminant rich liquid stream and a contaminant lean gaseous stream and reboiling the contaminant rich liquid stream providing a gaseous stream and feeding the gaseous stream to the purification column. A pressure difference between the contaminant rich liquid stream and the contaminant lean gaseous stream is provided before the streams enter the reboiler so that P contaminant rich liquid stream &lt;P contaiminant lean gaseous stream . More specifically this is obtained by subjecting the compressed stream to a) an absorption step in a column providing a contaminant lean gaseous stream leaving the top section of the column and a contaminant rich liquid stream leaving, optionally the bottom section of, the column and wherein the contaminant lean gaseous stream leaving the top section of the column is further subjected to the steps selected from: 
     1: b 1) compressing the contaminant lean gaseous stream providing a compressed gaseous stream; c1) cooling the compressed gaseous stream in a reboiler providing at least a product stream to be condensed and distilled, and a gaseous stream; and d1) feeding the gaseous stream to the purification column at the bottom section of the column; and 
     2: b2) cooling the contaminant lean gaseous stream in a reboiler providing at least a product stream to be further condensed and distilled and a gaseous stream; and c2) compressing the gaseous stream providing a cooled compressed gaseous stream; d2) feeding the cooled compressed gaseous stream to the column at the bottom section of the column; and depressurizing the contaminant rich liquid stream leaving at the bottom section of the column before entering the reboiler. The depressurization is in a particular embodiment obtained by means of a valve. 
     The carbon dioxide scrubber may comprise an integrated water inhibitor or scavenger if necessary. When the starting gas originates from a fermentation process the gas will most likely comprise ethanol, which may serve as the water inhibitor. 
     This improvement according to PCT/DK2010/0501746 is particularly preferred when the stream comprises many contaminants in order to minimize the waste contaminant rich stream  204 . This ensures a high purity as well as a high yield. 
     After the absorption step, the carbon dioxide rich/contaminant lean gaseous stream  108  is filtered in the filter A 9 , the filter may be a mechanical filter, activated carbon filter or other type of adsorbent, where appropriate, removing traces of for example H2S. The filter is optional. 
     The filtered stream  109  is condensed in the condenser A 4 . The condenser may be incorporated in the distillation column A 5 , as embodied in  FIG. 1 . It is also contemplated that the units are separate as illustrated in  FIGS. 2, 3 and 5 . The condensation is performed by the coolant  301 , providing a warmer coolant  302 . The coolant is any fluid having a cooling effect sufficient to condense the carbon dioxide at the high pressures contemplated. Particularly preferred is a coolant present in the brewery, or bottlery for example brine typically having a temperature between −5° C. and +5° C., such as −2 or −3° C., used for example for cooling the fermentation tanks. Thereby the condensation is obtained without any external supply of energy or without adding further equipment to the plant. In a particularly preferred embodiment (not shown) liquefied carbon dioxide is taken from the storage tank A 7  and is re-evaporated using the incoming coolant  301 . In this embodiment the liquefied carbon dioxide is preferably taken from the storage tank, and the coolant is cooled, by means of the evaporating carbon dioxide, to a lower temperature before entering the condenser A 4 . After leaving the condenser A 4  the temperature of the warmer coolant  302  could be returned to the temperature as initially supplied. Consequently, the condensation process is completely energy neutral which is of great economic advance over the prior art. 
     After condensation, the condensate  111 _ 1  is distilled to further purify the carbon dioxide which provides the liquefied carbon dioxide stream  112 , it is contemplated that gaseous carbon dioxide arises from the distillation unit to i.a. the condensation unit as will appear from  FIGS. 1 and 3 . A portion of the liquefied carbon dioxide stream  112  may be taken as the absorbent  111  when liquid carbon dioxide is used as the absorbent in the absorption step. 
     In  FIG. 2  another embodiment of the process according to the invention is shown. The reference signs of  FIGS. 1 and 3  also apply to  FIG. 2 . The downstream processes in the embodiment of  FIG. 2  are detailed in  FIG. 5 . Thus, reference is made to both  FIGS. 1, 3 and 5 . A variation of the CO2 scrub reboiler, A 10 _ 1 , is shown in  FIG. 2 . In this embodiment the CO2 scrub reboiler A 10 _ 1  is connected to the stream leaving the last compressing means before entering the absorption column A 3 . 
     In the embodiment shown in  FIG. 4 , which is a detailed view of the downstream processes of the embodiment shown in  FIG. 1 , the liquefied carbon dioxide stream  112  is depressurized whereby a certain amount of flash gas is created. Before the liquefaction the stream is, optionally, sub-cooled once or twice (shown) by means of sub-coolers A 11  and A 1   1 _ 1 , the sub-coolers may be driven by means of brine or carbon dioxide or both whichever is appropriate for the particular stream being cooled. The proportion of flash gas depends on the difference in pressure. In a typical embodiment where the pressure is reduced from 35 to 16 bar, 16 bar being the industry standard for carbon dioxide storage tanks, the amount of flash gas is 20% of the total stream. Liquid and gas are separated in the separator A 6  providing the depressurized liquid  114  for storage in the storage tank A 7 . The separator A 6 , for example a flash distillation column, also provides the flash gas  113 . This flash gas  113  is, in the embodiment shown, returned to a position before the final compression stage, for purification again. Alternatively, another compressor may be present between the separator A 6  and the condenser A 4  whereby the flash gas  113  may be condensed and distilled again. 
     In the embodiment shown in  FIG. 5  the condensate  111 _ 1  is depressurized before distillation. The condensate  111 _ 1  may in the embodiment shown, have a pressure of 47 bar. The condensate  111 _ 1  may in a preferred embodiment pass a sub-cooler, A 11 _ 1 . The purpose of adding a sub-cooler is to minimize the amount of the flash gas  113  recycled to the compression and purification step. Thus the sub-cooling reduces the overall energy consumption. The sub-cooling may also be added for technical reasons to protect the equipment, such as avoiding freezing if water is present in the compressed gaseous stream  104  of i.a.  FIG. 1 . 
     After the, optional, sub-cooling, the condensed sub-cooled stream  111 _ 2 , is passed through a second reboiler, A 12 , providing the cool sub-cooled high pressure stream  111 _ 3 . The pressure of the stream  111 _ 3  is then reduced, for example from 47 bar to 16 bar, to the depressurized stream  111 _ 4  whereby a substantial amount of the stream evaporates and provides a flash gas which is usable in the distillation step e) in the distillation column A 5 . 
     In a saturated stream (i.e. +12° C.) approximately 30% of the incoming stream will evaporate to form a flash gas when reducing the pressure. When the condensed sub-cooled stream  111 _ 2  is sub-cooled to +1° C. the portion will be approximately 20%, if further sub-cooled to −11° C. the portion will be approximately 12%. 
     In this setup, the reduction of the pressure results in the flash gas being formed, the flash gas can be used in the final distillation step (step e). 
     First, the condensed sub-cooled stream  111 _ 2  enters the reboiler A 12 . This condensed sub-cooled stream  111 _ 2  is warmer than an incoming cooler stream  111 _ 5 _ 1  being at a lower pressure, typically the liquid carbon dioxide taken from the bottom section of the distillation column A 5  in the embodiment shown. The heat of the condensed sub-cooled stream  111 _ 2  is transferred to the cooler stream  111 _ 5 _ 1  to give the re-evaporated stream  111 _ 6  entering the distillation column again. The now cooler sub-cooled high pressure stream  111 _ 3  is then subjected to a reduction in pressure whereby the even cooler mixed phase depressurized stream  111 _ 4  is provided. The depressurized stream  111 _ 4  enters the distillation column A 5  where the liquid fraction is purified by the countercurrent re-evaporated gaseous stream  111 _ 6  providing the purified liquid carbon dioxide  111 _ 5 . The purified liquid carbon dioxide  111 _ 5  is split in two fractions  111 _ 5 _ 1  (the cooler stream), and  111 _ 5 _ 2  (the product) of which 111_ 5 _ 1  is fed to the reboiler A 12  and  111 _ 5 _ 2  is the product. 
     Thereby the distillation step is energy neutral because there is no need for external supply of heat or cold. 
     Compared to the embodiment shown in  FIG. 4  the heat supplied to the reboiler A 8  originating from the process upstream as shown in  FIG. 3  (and  FIGS. 1 and 2 ), is not necessary. 
     Instead, in the embodiment shown in  FIG. 5  it may be beneficial to include an additional heat exchanging step by means of a heat exchanger A 18 , at a position after the last compressor A 1 _ 3  in order to extract heat from the system. This will minimize the amount of brine used further downstream in the process in the condenser A 4  where carbon dioxide is liquefied. 
     This heat extraction is effectuated by means of a heat exchanger using cooling water or air. When inserting the heat exchanger after the compression step b), this embodiment utilizes less power than the embodiment of  FIG. 1  as stream  106  is cooled by e.g. air or cooling water instead of brine. 
     In another preferred embodiment (shown in both  FIGS. 4 and 5 ) a second heat exchanging step combined with a re-evaporation step is inserted after the condensing step d). This embodiment is beneficial in both the high and low pressure distillation embodiment of  FIGS. 4 and 5 , respectively. 
     In this particular embodiment the purge gas  110  (gaseous carbon dioxide stream) leaving the condenser A 4  is passed to a second condenser A 13  connected to a loop with a valve A 14  or similar means for reducing the pressure of the purge gas  110 , for example from 47 to 16 bar similar to the depressurization described for the embodiment illustrated in  FIG. 5 . This depressurization also results in a mixed phase stream comprising up to 30% flash gas. The reduction in pressure entails a reduction of the temperature of approximately 30%, in this embodiment from −34° C. to −44° C. due to the content of non-condensable gases. 
     The stream being cooled to −44° C. entails that less carbon dioxide is present in the final purge stream  118 . Thus, the result of inserting this additional condensing step of the purge gas  110  coming from the first condensing step d) is that the amount of carbon dioxide discarded with the final purge stream  118  is markedly reduced, i.e. from 1300 kg/h to 190 kg/h for the example illustrated. Hence, the overall yield of carbon dioxide is increased. 
     It is also contemplated in a preferred embodiment that the flash gas  113  is used directly in the brewery production line as cover gas or for carbonating the beverages. 
     Finally, it is contemplated that the gas is condensed using the cooling effect from the re-evaporation of the liquid carbon dioxide. 
     The stored liquefied carbon dioxide may be taken from the storage tank as stored stream  116  and re-evaporated for use in the brewery. For re-evaporation the coolant  301  is preferably used before entering the condenser A 4  as detailed above. 
     It is also contemplated that heat exchangers, pumps, valves etc. are present where appropriate in order to start and maintain the desired pressure, temperature and other parameters throughout the method. Such provisions are within the skill of the art. 
     Now referring to  FIG. 6 , another particular aspect and embodiment of the invention will be described in further details. 
     At the time of i.a. carbonating the beverages in the brewery, liquefied carbon dioxide may be taken from the storage tank A 7  or directly from the distillation step e) as for example the flash gas  113 . 
     The liquefied carbon dioxide  116  from the tank or distillation column having a temperature typically in the range −30° C. to 20° C. and a pressure typically in the range 10 to 55 bar will in the embodiment be re-evaporated by use of a first heat exchanging means A 15 , preferably an evaporator, by contacting the liquefied carbon dioxide stream  116  with a coolant  401 , e.g. brine, taken from the brewery. 
     Hereby the temperature of the coolant  401  decreases from e.g. −5° C. to −8° C., and the temperature of the heated product stream  117  leaving the first heat exchanging means A 5  may increase to for example −6° C. A temperature of 25° C. may be obtained by two or more heat exchanging steps where the second and additional steps are typically not effectuated by using brine, but water, air or any other warmer media (not shown). The resulting coolant  402  is in a particularly preferred embodiment used as the coolant ( 301  in the process of  FIG. 1  as the condensing means A 4  of  FIG. 1 ), whereby the temperature of the coolant will increase typically to the initial temperature of the brine, i.e. −5° C. and can be used again in the brewery as such. 
     Further, the warmer now gaseous heated product stream  117  is then expanded by means of an expander A 16 . The temperature and pressure of the expanded product stream  119  may be from −55 to −20° C. and 5-7 bar, respectively. The expanded product stream  119  is heated by use of a second heat exchanging means A 17 . 
     In the second heat exchanging means A 17  the heating is in a particular embodiment effectuated by using a warmer coolant  501 , such as the warmer coolant  302  of  FIG. 1 . Thus, the warmer coolant  302 / 501  may have the same origin as the coolant used for the first heat exchanging means A 15 , the warm coolant ( 302  of  FIG. 1 ) leaving the condenser A 4 , or may be taken directly from a coolant storage tank (not shown). The expansion and respective heating steps can be performed in one or more steps. 
     The cooling power obtained may be used for example in the condenser A 4 . 
     The gaseous carbon dioxide stream  120  leaving the second heat exchanging means A 17  could have a temperature of approximately 5-25° C. and a pressure of 1-6 bar and may be used in the distillery/bottlery etc. as such. 
     By use of the first and second heat exchanging means (A 15  and A 17 ) between 90 and 115 kWh cold energy per ton carbon dioxide may be recovered. Furthermore, by use of the expander A 16  additionally 10 to 20 kW power may be recovered compared to a conventional process using a valve and heat exchanger. The recovered power may either be used for compression work elsewhere in the carbon dioxide recovery process, in the brewery or elsewhere. 
     It is also contemplated that this latter aspect and/or embodiment is implemented at any site where liquefied carbon dioxide is being re-evaporated for use and it should not be restricted to the method of the invention. 
     It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein. Various features and advantages of the invention are set forth in the following claims.