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EP-4735812-A1 - METHOD AND DEVICE FOR SEPARATING A MIXTURE CONTAINING CO2 VIA PARTIAL CONDENSATION AND/OR DISTILLATION

EP4735812A1EP 4735812 A1EP4735812 A1EP 4735812A1EP-4735812-A1

Abstract

The invention relates to a method for separating a gaseous mixture containing CO2, nitrogen and oxygen, wherein the compressed, cooled and dried gaseous mixture (11) is separated via partial condensation and/or distillation (CC) to form a CO2-rich fluid (21) and/or a CO2-rich gas, and wherein, in a first operating mode, a stream which is part of the compressed, cooled and dried stream (23) is sent to a buffer capacity (B) and stored and, in a second operating mode, a gaseous stream (31) stored in the buffer capacity (B) is sent upstream of the washing unit.

Inventors

  • MARTY, PASCAL
  • MURINO, Michele
  • MADELAINE, Laurette
  • GRANADOS, LUDOVIC

Assignees

  • L'AIR LIQUIDE, SOCIETE ANONYME POUR L'ETUDE ET L'EXPLOITATION DES PROCEDES GEORGES CLAUDE

Dates

Publication Date
20260506
Application Date
20240624

Claims (15)

  1. Process for separating a gas mixture containing CO2, nitrogen and oxygen in which: The mixture (1) is purified by washing with water in a washing unit (Q) producing a purified flow (5) containing water, The purified flow is compressed in a compressor (C2) to form a compressed flow and then cooled and dried (D) forming a compressed, cooled and dried flow (11) At least a portion (17) of the compressed, cooled and dried flow is separated by partial condensation and/or distillation (CC) forming a liquid (21) rich in CO2 and/or a gas rich in CO2 in which during a first mode of operation the gas mixture has a flow rate d and a molar mass in CO2 of C and a flow which is a part of the compressed, cooled and dried flow (23) and optionally From the compressed flow taken upstream of cooling and/or drying (26, 29) and/or Gas rich in CO2 and/or CO2-rich liquid (21) from partial condensation and/or distillation that has been vaporized is sent to a buffer capacity (B) and stored and in which during a second mode of operation, the gas mixture (1) has a flow rate less than d, or even zero and/or a molar mass in CO2 less than C and a gas flow (4, 31, 32, 33, 34) stored in the buffer capacity (B) is sent upstream of the washing unit or upstream of the compressor of the purified flow or upstream of the partial condensation and/or distillation unit.
  2. Process for separating a gas mixture (1) containing CO2, nitrogen and oxygen in which: The mixture is purified by washing with water in a washing unit (Q) producing a purified flow (5) containing water, The purified flow is compressed in a compressor (C2) to form a compressed flow and then cooled and dried forming a compressed, cooled and dried flow (11) At least a portion of the compressed, cooled and dried flow is separated by adsorption or permeation in a preconcentration unit (A) forming a nitrogen-enriched and CO2-depleted gas (13) and a CO2-enriched and nitrogen-depleted gas (15), The CO2-enriched gas is optionally compressed, optionally cooled and then separated by partial condensation and/or distillation in a partial condensation and/or distillation unit (CC) forming a CO2-rich liquid (21) and/or a CO2-rich gas. in which during a first mode of operation the gas mixture has a flow rate d and a molar mass in CO2 of C and a flow which is a part of the compressed, cooled and dried flow (23) and optionally From the compressed flow taken upstream of cooling and/or drying (26, 29) and/or Gas enriched with CO2 (27) and/or Gas rich in CO2 and/or CO2-rich liquid (21) from partial condensation and/or distillation that has been vaporized is sent to a buffer capacity (B) and stored and in which during a second mode of operation, the gas mixture has a flow rate less than d, or even zero and/or a molar mass in CO2 less than C and a gas flow stored (4, 31, 32, 33, 34) in the buffer capacity is sent upstream of the washing unit or upstream of the compressor of the purified flow or upstream of the partial condensation and/or distillation unit and downstream of the preconcentration unit.
  3. Method according to claim 1 or 2 in which the buffer capacity (B) stores the gas (26, 29, 23, 27, 21) during the first mode of operation at a pressure greater than 6 bars abs, or even at least equal to 8 bars abs and preferably less than 30 bars abs.
  4. Method according to one of the preceding claims during the second mode of operation, the gas flow (3, 31, 33) stored in the buffer capacity is expanded before being sent upstream of the washing unit (Q) or upstream of the compressor of the purified flow (C2) or upstream of the partial condensation and/or distillation unit (CC) and possibly downstream of the preconcentration unit (A).
  5. Method according to one of the preceding claims, during the first mode of operation, the flow (26, 29, 23, 27, 21) intended for the buffer capacity (B) is heated upstream of the buffer capacity.
  6. Method according to claim 4 in which the buffer capacity (B) stores the gas (26, 29, 23, 27, 21) at a temperature above 80°C.
  7. Method according to one of claims 4 or 5 in which the temperature in the buffer capacity (B) is regulated during the second mode of operation to maintain the temperature above a threshold.
  8. Method according to one of the preceding claims, in which during the first mode of operation a flow (23) which is a part of the compressed, cooled and dried flow is sent to the buffer capacity (B) and stored.
  9. Method according to one of the preceding claims, in which during the first mode of operation, no gas leaves the buffer capacity (B) to be separated in the preconcentration unit (A), if present, or the partial condensation and/or distillation unit (CC).
  10. Method according to one of the preceding claims, in which during the second mode of operation, no gas is sent to the buffer capacity (B).
  11. Method according to one of the preceding claims, in which during the second mode of operation, the buffer capacity (B) is depressurized, preferably to atmospheric pressure.
  12. A method according to claim 2 or one of the preceding claims when dependent on claim 2 wherein during the first mode of operation, the buffer capacity (B) stores gas at the inlet pressure of the preconcentration unit (A).
  13. Method according to one of the preceding claims, in which during the first mode of operation, the buffer capacity (B) stores gas at the inlet pressure of the partial condensation and/or distillation separation unit (CC).
  14. Method according to one of the preceding claims, in which during a second mode of operation, the gas mixture has a flow rate less than d, or even zero and/or a molar mass in CO2 less than T, a gas flow stored in the buffer capacity (B) is sent upstream of the washing unit (Q).
  15. Method according to one of the preceding claims, in which during a second mode of operation, the gas mixture has a flow rate less than d, or even zero and/or a molar mass in CO2 less than T, a gas flow (32) stored in the buffer capacity is sent upstream of the compressor of the purified flow (C2).

Description

Process and apparatus for separating a mixture containing CO2 by partial condensation and/or distillation The present invention relates to a method and apparatus for separating a mixture containing CO2 by partial condensation and/or distillation. The mixture contains CO2, nitrogen, oxygen, possibly argon, possibly water. The process produces a CO2-rich gas, containing at least 80 mol% CO2, or even at least 95 mol% CO2, and/or a CO2-rich liquid, containing at least 80 mol% CO2, or even at least 95 mol% CO2. Some CO2 capture processes, particularly cryogenic processes, should preferably operate continuously and if possible with limited fluctuations in flow rates and molar mass. In order to homogenize the compositions and average the gas flow rates feeding such units, the usual solution is to set up a gasholder: the gases (of variable flow and composition) are stored for a certain time (called "residence time") in an enclosure, such as a gasholder, which can be of variable volume or pressure, to possibly ensure a more homogeneous mixture, generally at low pressure (i.e., close to atmospheric pressure) and an averaged flow rate feeding the CO2 capture unit which is continuously withdrawn. It will be ensured that the different gases feeding the gasholder are properly mixed by the positioning and orientation of judicious gas inlets/outlets or recirculations or specific designs of injection pipes. Parallel Flow Regenerative Kilns (PFRK) cement plants operate according to a cyclic process using pairs of kilns, one kiln being in lime production mode, the second being in regeneration mode, fumes of different compositions and flow rates being emitted during a cycle and the CO2 having to be captured from the fumes generated by the process: [TAB.1] Nominal operation Smoke flow rate Nm 3 /h 33,000 Operating temperature / max ℃ 120°C Pressure bara ATM Composition during NominalCO2 mol% 22.9 H 2 O mol% 6.5 O 2 mol% 8.4 N 2 mol% 61.3 Ar mol% 0.7 Production time minutes 13 Reversal time minutes 1 If the CO2 in the flue gases is not captured during the inversion time (i.e. the flue gases do not feed the CC unit for 1 minute every 14 minutes), an initial calculation defines that a “useful” or “displaced” storage volume at P atm of approximately 500 m3 for the nominal case above is necessary (gasometer). The absence of flue gases may possibly last less than a minute, for example of the order of ten seconds, but nevertheless disrupts the operation of the partial condensation separation and/or CC distillation unit. illustrates a CO2 purification process using a preconcentration unit A capable of separating a gas by adsorption or permeation and a partial condensation and/or distillation process CC. A gas 1 at atmospheric pressure and a temperature of 120°C containing CO 2 , nitrogen, oxygen, argon as well as impurities such as NO x and/or SO x is compressed in a compressor C1 forming a compressed gas 3, washed with water 4 and/or a basic component in a washing unit Q to remove impurities such as NO x and SO x . The washed gas 5 is heated in a heater H and sent to a compressor C2 where it is compressed forming a compressed gas 8, cooled in a cooler R forming a cooled gas 9, dried in a dryer D for example by temperature swing adsorption and sent as dried gas 11 to a preconcentration unit, for example separation unit A by pressure swing adsorption producing a nitrogen-enriched and CO2- depleted gas 13 and a CO2 -enriched and nitrogen-depleted gas 15. The gas 13 is compressed in a compressor C3 forming a gas 17, is cooled and then separated by partial condensation and/or distillation forming a CO2 -rich liquid, containing at least 80 mol% CO2 . Gas 1 comes from a flue gas source that is not operating permanently. To supply separation units A, CC during periods when gas is not available, a portion 6 of the gas heated in heater H is sent to a gasometer G while gas 1 is available and stored. While gas 1, 6 is not available, it is gasometer G that sends gas to compressor C2. A similar method is known from WO2006/106253 and EP-A-341879. According to one object of the invention, there is provided a method for separating a gas mixture containing CO2, nitrogen and oxygen in which: i. The mixture is purified by washing with water in a washing unit producing a purified flow containing water, ii. The purified flow is compressed in a compressor to form a compressed flow and then cooled and dried forming a compressed flow, cooled and dried iii. At least a portion of the compressed, cooled and dried flow is separated by partial condensation and/or distillation forming a CO2-rich liquid and/or a CO2-rich gas. in which during a first mode of operation the gas mixture has a flow rate d and a molar mass in CO2 of C and a flow which is a part of the compressed, cooled and dried flow and optionally From the compressed flow taken upstream of cooling and/or drying and/or Gas rich in CO2 and/or Gas enriched with CO2 and/or CO2-rich liquid from partial cond