Process and apparatus for the simultaneous production of gaseous and liquid CO2
The process addresses the challenge of simultaneous CO2 production by employing partial condensation and distillation with controlled vaporization and compression, achieving flexible and efficient production of both gaseous and liquid CO2 while optimizing operational efficiency and reducing costs.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2024-03-18
- Publication Date
- 2026-03-20
AI Technical Summary
Existing CO2-rich gas treatment processes primarily produce either purified gaseous or liquid CO2, lacking a cost-effective and flexible method for simultaneous production of both forms.
A process involving partial condensation, distillation, and solidification to separate CO2 from a gaseous mixture, with controlled vaporization and compression stages to produce gaseous and liquid CO2, utilizing refrigeration cycles and storage to manage production flexibility.
Enables simultaneous and flexible production of gaseous and liquid CO2 with optimized operational efficiency and reduced costs, maintaining stable operating conditions across varying production ratios.
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Abstract
Description
Title of the invention: Method and apparatus for the simultaneous production of gaseous and liquid CO2
[0001] The present invention relates to a method and apparatus for the simultaneous production of gaseous and liquid CO2 from a gaseous mixture containing CO2 and at least one component lighter than CO2.
[0002] Many schemes of CO2-rich gas treatment processes with CO2 extraction exist, but most of them are based on the production of purified CO2 either entirely gaseous or entirely liquid.
[0003] The possibility of simultaneously producing purified gaseous and liquid CO2 from a CO2-rich source implies higher investments, and particular attention must be paid to optimizing operating costs. One objective of this invention is to design a process capable of producing gaseous and liquid CO2 and to find the most economically viable process integration arrangement, offering the greatest operational flexibility between gaseous and liquid CO2 production.
[0004] FR-A-3120427 describes a process for separating a stream containing CO2 to simultaneously produce liquid CO2 and gaseous CO2, resulting from the vaporization of a flow of liquid CO2.
[0005] The present invention proposes to produce at least part of the liquid CO2 by condensing gaseous CO2 and storing it in liquid form
[0006] We can define:
[0007] [TAB.l] q Quantity of CO2 exported q0 Nominal quantity of CO2 produced qG Quantity of gaseous CO2 exported qL Quantity of liquid CO2 exported qLP Quantity of liquid CO2 produced by condensing gaseous CO2 zL Limit of the quantity of liquid CO2, defined by the lower charge limit n Number of external refrigerant cycles s Quantity of liquid CO2 to be sent to storage F, F0 Feed rate, nominal feed rate qLa Quantity of liquid, defined by excess cooling zO Minimum machine charge m % of qLP per refrigeration cycle (=q0 / n for homogeneous partitioning)
[0008] Thus
[0009] qG + qL = q
[0010] qLP = qL + s
[0011] qLP can vary between the following values: • [0 (no LCO2 production); y (corresponding to excess cold)] • [zL; q (without GCO2 production)], zL>y with the lower limit zL discussed below.
[0012] A liquid storage is used to ensure the entire range of liquid production qLe[y ; zL] or [0 ; zL], for other discontinuous ranges or for CO2 production beyond the charging capacity (q>qO for F0 feed for example), the liquid storage will be filled as described below.
[0013] It should be noted that since there is excess cooling due to the vaporization of liquid carbon dioxide withdrawn from the tank of the stripping column, it is possible to withdraw a quantity qLa of LCO2 produced, for example by the column, with little effect on the design of the heat exchanger.
[0014] In this example, qLa constitutes between 7 and 8% of the liquid CO2 production. If all the liquid produced in the column vessel is vaporized in the HEX1 heat exchanger, there is excess cold at the hot end of the exchanger. The quantity yO is the maximum amount of CO2 that can be withdrawn from the column vessel, respecting the AT specification in the HEX1 exchanger. [Fig. 1] shows the variation of AT with temperature in the HEX1 exchanger.
[0015] According to one object of the invention, a process is provided for the simultaneous production of gaseous CO2 and liquid CO2 from a gaseous mixture containing CO2 and at least one component lighter than CO2, in which the gaseous mixture is separated by partial condensation and / or distillation and / or solidification, producing a first liquid at a first pressure richer in CO2 than the gaseous mixture; a first part of the first liquid is completely vaporized at the first pressure by heat exchange with the mixture, forming a first gas rich in CO2; a second part of the first liquid is completely vaporized at a second pressure lower than the first pressure by heat exchange with the mixture, forming a second gas rich in CO2; the second gas is compressed in at least one stage of a compressor from the second pressure to substantially the first pressure.The first and second gases are mixed at the first pressure, forming a third gas, and simultaneously,
[0016] i) a first fraction of the third CO2-rich gas is at least partially liquefied at the first pressure, by heat exchange with at least one re-cycle refrigeration, producing a third CO2-rich liquid which is pressurized by a pump to constitute at least part of the liquid CO2 produced and / or a second fraction of the third CO2-rich gas is liquefied at the first pressure, by heat exchange with at least one refrigeration cycle and sent at least occasionally to storage and
[0017] ii) a third fraction of the third CO2-rich gas has not been liquefied and constitutes a gaseous product of the process.
[0018] According to other optional features:
[0019] • the third fraction of the third CO2-rich gas is compressed by at least one stage of a compressor, preferably of the centrifugal type, from substantially the first pressure up to a fourth pressure.
[0020] • the second gas is compressed in at least one stage of a compressor and the the third fraction is compressed in at least one stage of the same compressor, preferably of the centrifugal type, downstream of at least one stage where the second gas is compressed.
[0021] • at least the first part of the first liquid is vaporized without having been relaxed or pressurized.
[0022] • the mixture is separated in at least one phase separator and at least one liquid from at least one phase separator is sent to a stripping column, the column tank liquid constituting the first liquid and the column operating at the first pressure.
[0023] • the second part of the first liquid, possibly coming from the tank of the column, is relaxed in a valve until the second pressure, before being vaporized and compressed.
[0024] • the column operates at between 10 and 20 bars abs, or even between 10 and 20 bars abs
[0025] • a third part of the first liquid also constitutes a liquid product of the process.
[0026] • according to one variant a) a first flow rate of the first and / or second fraction of the a third CO2-rich gas is at least partially liquefied by heat exchange with at least one refrigeration cycle, the at least one refrigeration cycle comprising a cycle compressor driven by an electric motor, producing a CO2-rich liquid if the electricity supplied to the motor has a price below a threshold and
[0027] • according to variant b) a second flow rate of the first and / or second fraction of the A third CO2-rich gas, with a flow rate lower than the first, or even zero, is at least partially liquefied by heat exchange with at least one refrigeration cycle. This refrigeration cycle includes a cycle compressor driven by an electric motor, producing the CO2-rich liquid if electricity is supplied to the motor. has a price above the threshold.
[0028] • according to one variant a) a first flow rate of the first and / or second fraction of the a third CO2-rich gas is at least partially liquefied by heat exchange with at least one refrigeration cycle, the at least one refrigeration cycle comprising a cycle compressor driven by an electric motor, producing a CO2-rich liquid if a first percentage of the electricity sent to the motor comes from at least one renewable source and
[0029] • according to variant b) a second flow rate of the first and / or second fraction of the a third CO2-rich gas, lower than the first flow rate or even zero, is liquefied at least partially by heat exchange with at least one refrigeration cycle, the at least one refrigeration cycle comprising a cycle compressor driven by an electric motor, producing the CO2-rich liquid if a second percentage, lower than the first percentage or even zero, of the electricity sent to the motor comes from at least one renewable source. • the ratio between the flow rates of the first and third fractions is variable and / or the ratio between the flow rates of the second and third fractions is variable. • according to variant i) according to a first step of the device, the ratio between the flow rates of the first and third fractions is x : 1 and
[0030] i) according to a second step of the apparatus, the ratio between the flow rates of the first and third fractions is y:1, y being greater than x. • according to variant i) according to a first step of the device, the ratio between the flow rates of the second and third fractions is x : 1 and
[0031] ii) according to a second step of the apparatus, the ratio between the flow rates of the second and third fractions is y:1, y being greater than x. • The entire second part of the first liquid, completely vaporized at a second pressure, is compressed and mixed with the first part of the first liquid, completely vaporized at the first pressure. • a gas from a gaseous sky of the storage is sent upstream of at least one compression stage or upstream of a point where the first and second gases mix at the first pressure forming the third gas or mixes with the second gas upstream of its compression to the first pressure.
[0032] According to another object of the invention, an apparatus for the simultaneous production of gaseous CO2 and liquid CO2 from a gaseous mixture containing CO2 and at least one component lighter than CO2 is provided, comprising a separation unit by partial condensation and / or distillation and / or solidification for separating the gaseous mixture, and means for extracting a first liquid from the separation unit at a a first pressure richer in CO2 than the gaseous mixture, a heat exchanger, means for sending a first part of the first liquid to vaporize completely at the first pressure in the heat exchanger, by heat exchange with the mixture forming a first gas rich in CO2, means for sending a second part of the first liquid to vaporize completely at a second pressure lower than the first pressure in the heat exchanger by heat exchange with the mixture forming a second gas rich in CO2, a compressor, means for sending the second gas to be compressed in at least one stage of the compressor from the second pressure down to substantially the first pressure, means for mixing the first and second gases at the first pressure forming a third gas, and
[0033] a) means for liquefying a first fraction of the third CO2-rich gas at least partially at the first pressure, comprising at least one refrigeration cycle and capable of producing a third CO2-rich liquid and a pump for pressurizing the third liquid to constitute at least part of the liquid CO2 produced and / or
[0034] b) a storage and means for liquefying a second fraction of the third CO2-rich gas at the first pressure, by heat exchange comprising at least one refrigeration cycle and means for sending the second liquefied fraction at least occasionally to the storage and
[0035] c) means for removing a third fraction of the third CO2-rich gas as a gaseous product of the process, these means not including liquefaction means.
[0036] The invention will be described in more detail with reference to the figures, where:
[0037] [Fig.2] represents a method according to the invention.
[0038] [Fig-2] represents a process according to the invention in which a mixture S101 of CO2 and at least one lighter component, for example hydrogen, helium, oxygen, Nitrogen, methane, carbon monoxide, ethane or other hydrocarbon is separated by partial condensation and distillation.
[0039] The mixture S101 with a flow rate F, pressure PI, and temperature T1 is cooled and partially condensed in a brazed-plate wave heat exchanger HEX1. The partially condensed flow S102 at a temperature T2 is sent to a phase separator, forming a gas S104 and a liquid S103. The gas S104 is heated in the exchanger HEX1. The liquid S103 is expanded in a valve EXP1 to a pressure P2 and a temperature T3 and sent to the top of a column T100. The top gas S106 of the column T100, enriched in at least one lighter component and depleted in CO2, is heated in the exchanger HEX1 and rejoins the flow S104, forming a flow S107.
[0040] The tank liquid from column T100 constitutes part of the liquid product of the CO2 LIQ process. A portion SI 11 of the liquid is vaporized in the heat exchanger HEX1 at pressure P2, between 10 and 20 bar abs of the column, and returned as a gas to column T100 in the tank to reboil the column. Another flow SI 10 of the tank liquid at pressure P2 and temperature T4 vaporizes in the heat exchanger HEX1 without having been expanded, forming a flow SI 15. Another flow of the tank liquid S108 is expanded in a valve EXP2, forming a flow S109 at pressure P3 and temperature T5, and vaporized in the heat exchanger HEX1 at pressure P3, which is lower than P2. The vaporized flow SI 13 is compressed in a compressor Cl, cooled in a re-cooler forming the flow SI 14 up to the pressure P2 which is that of the column and the two vaporized flows SI 14, SI 15 are mixed forming a third gaseous flow at a pressure between 10 and 20 bar abs.
[0041] The third gas flow is divided into two parts. One part can directly constitute the gaseous product at pressure P2 or otherwise this part can be sent at least in part to a compressor C2, cooled forming a flow SI 16 of gaseous CO2 at a pressure P5, serving as the product of the process.
[0042] Another portion qLP of the third gas flow is sent, at least in part, to a heat exchanger HEX3 to be condensed at pressure P2 by at least one closed refrigeration cycle 100, involving a cycle compressor C3, a re-cooler, a valve, and a phase separator. The cycle refrigerant, for example NH3, is compressed by the cycle compressor C3, cooled, and expanded in the valve, forming a two-phase flow. The two-phase flow separates in a phase separator, with the gas being sent upstream of the compressor and the liquid being vaporized in the heat exchanger HEX3.
[0043] The gaseous flow SI 17 exits the HEX3 exchanger in condensed form at pressure P2, which is that of the T100 column, and is pressurized by a pump to a pressure greater than P2, which may be supercritical, forming a flow SI 18. At least a portion of the condensed flow SI 18 can be sent as flow s to a liquid storage S and / or used as a liquid product without passing through the storage S. If production is required above the column's capacity, a flow ds can be drawn from the storage S to supply the missing quantity of liquid.
[0044] The production of a greater quantity (qLP>qLa) of purified LCO2 requires the use of at least one external refrigeration cycle 100, using a refrigerant such as NH3 to cool a portion of the product (a mixture of SI 14 and SI 15) to condense a portion of the GCO2 in the heat exchanger HEX 3 at a pressure that differs from that of the column only by pressure losses. The resulting condensed CO2 LCO2 S117 can be pumped to a higher pressure, forming a liquid flow SI 18.
[0045] The scheme regarding the GCO2 / LCO2 ratio depends on the minimum possible flow rate for the CO2 compressor C2 and the minimum possible flow rate for the refrigeration cycle compressor C3. Depending on the required flexibility, it might be advantageous to perform the C2 and / or C3 compression using several compressors in parallel (2*50% capacity or 3*33% capacity, etc.) or several cycle compressors in parallel.
[0046] For a liquid production qLP > zL, the quantity qLPi is sent to the HEX 3 heat exchanger to be condensed against the refrigeration cycle. The cycle compressor C3 must manage a variation in the refrigerant flow rate as a function of the CO2 flow rate qLP to be condensed. Thus, the value of zL is defined by the minimum flow rate of the refrigerant compressor C3.
[0047] Several external cycles or several refrigerant compressors can be used in parallel to optimize the flexibility of the scheme by adjusting the flow rate reduction of the cycle(s) or compressor(s). It is also possible to close one or more cycles or compressors simultaneously.
[0048] The minimum quantity of gaseous CO2 to be produced can be limited by the minimum flow rate that can be compressed by the compressor C2. This limitation can be eliminated by recycling the CO2 compressed after expansion (line R) through a recirculation valve at the compressor inlet. This solution increases energy consumption.
[0049] A storage S can be used to make the production of liquid and gaseous CO2 more flexible.
[0050] The discontinuous production of liquid CO2 by the cryogenic unit can be compensated by a liquid CO2 storage connected to the distillation apparatus.
[0051] In one example, we can: • Fill the storage • when qL < zL / n (the quantity of LCO2 to be exported corresponds to (a) the charge of at least one refrigerant cycle if below its minimum flow rate(s); and at least one refrigerant cycle / compressor is not stopped but is operating at its maximum flow rate). Thus qLP = zL = qL + s and / or • after a fraction when at least one cycle / compressor is not stopped. Thus qLP = qL+s and / or • at night when electricity costs are lower and / or • during periods when renewable energy is available • Empty storage • When at least one refrigerant cycle is stopped to continue producing a minimum amount of LCO2). Thus qL = qLP +s and / or
[0052]
[0053]
[0054]
[0055]
[0056] • Regardless of the liquefier load, increase the L / G ratio of CO2 produced to operate at an OPEX optimum. Thus, qL > qLP and / or • When the liquefier operates at reduced load With gaseous and liquid CO2 production below nominal production and / or With nominal gaseous and liquid CO2 production (F <F0, qL + qG = qO) et / ou • When the liquefier is operated at nominal gas and liquid production and a higher gas and liquid production is required (F=F0, qL>qLP) [TAB.2] (example) CASE Feed charge Liquid CO2 production Gaseous CO2 production Storage 0 - Nominal F0 qLO qGO 0 to zL / n OR sO 1 - Reduced charge F < F0 qL0=qLP+s 1 qGO -s 2 - Increased production F0 qL2=qLP+s2 qGO -s2 3 - Reduced production F0 qL3=qLP-s3 qGO s3 In case 1, liquid from storage S compensates for the lack of condensed liquid due to the reduction in load. In case 2, liquid s2 from storage S completes the quantity of condensed liquid. In case 3, liquid s3 goes to storage S because it is not required for production. A BOG gas from the gaseous space of storage S can be sent upstream of compressor C2 and / or Cl or upstream of the point where gases S114 and S115 mix. • Advantages of the proposed solution • Production flexibility, gaseous G and / or liquid L with a variable L / G ratio • Multi-fluid heat exchanger with stable, or even constant, operating conditions • Separation apparatus with distillation column and / or of exhaustion having stable, or even constant, operating conditions Low-pressure compressor with stable, or even constant, operating conditions regardless of the gas / liquid production ratio Liquid storage allows for the supply of more liquid than that supplied by separation at any given time. The vaporized gas from the storage can be recycled to be liquefied and returned to the storage facility.
Claims
Demands
1. A process for the simultaneous production of gaseous CO2 and liquid CO2 from a gaseous mixture containing CO2 and at least one component lighter than CO2, wherein the gaseous mixture (S 101) is separated by partial condensation and / or distillation and / or solidification, producing a first liquid (S 108, SI 10) at a first pressure richer in CO2 than the gaseous mixture; a first part (SI 10) of the first liquid is completely vaporized at the first pressure by heat exchange with the mixture, forming a first gas (SI 15) rich in CO2; a second part (S 108) of the first liquid is completely vaporized at a second pressure lower than the first pressure by heat exchange with the mixture, forming a second gas (SI 13) rich in CO2; the second gas is compressed in at least one stage of a compressor (Cl) from the second pressure to substantially the first pressure.The first and second gases are mixed at the first pressure, forming a third gas, and simultaneously i. a first fraction (S 117, S118) of the third CO2-rich gas is at least partially liquefied at the first pressure by heat exchange with at least one refrigeration cycle (100), producing a third CO2-rich liquid which is pressurized by a pump to constitute at least part of the liquid CO2 produced, and / or a second fraction of the third CO2-rich gas is liquefied at the first pressure by heat exchange with at least one refrigeration cycle and sent at least occasionally to a storage (S), and ii. a third fraction (SI 16) of the third CO2-rich gas has not been liquefied and constitutes a gaseous product of the process.
2. A method according to claim 1 wherein the third fraction (SI 16) of the third CO2-rich gas is compressed by at least one stage of a compressor (C2), preferably of the centrifugal type, from substantially the first pressure up to a fourth pressure.
3. A method according to claim 2 wherein the second gas is compressed in at least one stage of a compressor (Cl) and the third fraction is compressed in at least one stage (C2) of the same compressor, preferably of the centrifugal type, downstream of the at least one stage where the second gas is compressed.
4. A method according to claim 1, 2 or 3 wherein at least the first part (SI 10) of the first liquid is vaporized without having been decompressed or pressurized.
5. A method according to claim 1, 2, 3 or 4 wherein the mixture is separated in at least one phase separator and at least one liquid from at least one phase separator is sent to a stripping column (T100), the column tank liquid constituting the first liquid and the column operating at the first pressure.
6. A method according to claims 4 and 5 wherein the second part of the first liquid, possibly from the column tank (T100), is depressurized in a valve (EXP 2) to the second pressure, before being vaporized and compressed.
7. A process according to any one of the preceding claims wherein a third part (qLa) of the first liquid also constitutes a liquid product of the process.
8. A method according to any one of the preceding claims wherein a. a first flow of the first and / or second fraction of the third CO2-rich gas is liquefied at least partially by heat exchange with at least one refrigeration cycle, the at least one refrigeration cycle comprising a cycle compressor driven by an electric motor, producing a CO2-rich liquid if the electricity sent to the motor has a price below a threshold and / or and b. a second flow of the first and / or second fraction of the third CO2-rich gas, lower than the first flow, or even zero, is liquefied at least partially by heat exchange with at least one refrigeration cycle, the at least one refrigeration cycle comprising a cycle compressor driven by an electric motor, producing the CO2-rich liquid if the electricity sent to the motor has a price above the threshold.
9. A method according to any one of the preceding claims, wherein a. a first flow of the first and / or second fraction of the a. a third CO2-rich gas is liquefied at least partially by heat exchange with at least one refrigeration cycle, the at least one refrigeration cycle comprising a cycle compressor driven by an electric motor, producing a CO2-rich liquid if a first percentage of the electricity sent to the motor comes from at least one renewable source and b. a second flow of the first and / or second fraction of the third CO2-rich gas, lower than the first flow, or even zero, is liquefied at least partially by heat exchange with at least one refrigeration cycle, the at least one refrigeration cycle comprising a cycle compressor driven by an electric motor, producing the CO2-rich liquid if a second percentage, lower than the first percentage, or even zero, of the electricity sent to the motor comes from at least one renewable source.
10. A method according to any one of the preceding claims wherein the ratio between the flow rates of the first and third fractions is variable and / or the ratio between the flow rates of the second and third fractions is variable.
11. A method according to any one of the preceding claims wherein all of the second part (SI 13) of the first liquid vaporized completely at a second pressure is compressed and mixed with the first part (SI 15) of the first liquid vaporized completely at the first pressure.
12. A method according to any one of the preceding claims wherein a gas (BOG) from a gaseous sky of the storage (S) is sent upstream of at least one compression stage (Cl, C2) or upstream of a point where the first and second gases mix at the first pressure forming the third gas or mixes with the second gas upstream of its compression to the first pressure.
13. Apparatus for the simultaneous production of gaseous CO2 and liquid CO2 from a gaseous mixture containing CO2 and at least one component lighter than CO2, comprising a separation unit by partial condensation and / or distillation and / or solidification (T2, T100) for separating the gaseous mixture, and means for exiting the unit a separation of a first liquid (S 108) at a first pressure richer in CO2 than the gaseous mixture, a heat exchanger (HEX1), means for sending a first part (SI 10) of the first liquid to vaporize completely at the first pressure in the heat exchanger, by heat exchange with the mixture forming a first gas rich in CO2, means for sending a second part (S 108) of the first liquid to vaporize completely at a second pressure lower than the first pressure in the heat exchanger by heat exchange with the mixture forming a second gas rich in CO2 (SI 14), a compressor (Cl), means for sending the second gas to be compressed in at least one stage of the compressor from the second pressure down to substantially the first pressure, means for mixing the first and second gases at the first pressure forming a third gas, and a. means (100, HEX3) for liquefying a first fraction of the third CO2-rich gas at least partially at the first pressure, comprising at least one refrigeration cycle and capable of producing a third CO2-rich liquid and a pump for pressurizing the third liquid to constitute at least part of the liquid CO2 produced and / or b. a storage (S) and means for liquefying a second fraction of the third CO2-rich gas at the first pressure, by heat exchange comprising at least one refrigeration cycle, and means for sending the second liquefied fraction at least occasionally to the storage and c. means for extracting a third fraction (SI 18) of the third CO2-rich gas as a gaseous product of the process, these means not including liquefaction means.