Method and apparatus for separating CO2 from at least two streams with different compositions

Abstract

Title: Method and apparatus for separating CO2 from at least two streams with different compositions In an integrated separation process, a first flow (1) containing a first percentage of CO2 is separated in a first separation unit (1F), a second flow (2) containing a second percentage of CO2 greater than the first percentage in a second separation unit (2F), the first separation unit and the second separation unit have a common final part (2G). Abstract figure: Fig. 1

Description

Title of the invention: Method and apparatus for separating CO2 from at least two streams with different compositions

[0001] The present invention relates to a method and apparatus for separating CO2 from at least two streams with different dry-based CO2 compositions.

[0002] At least one of the streams contains less than 50 mol% of CO2 on a dry basis, preferably less than 30 mol% of CO2 on a dry basis, or even less than 20 mol% of CO2 on a dry basis and at least one other of the streams contains more than 50 mol% of CO2 on a dry basis.

[0003] For example, at least one of the streams contains less than 25 mol% CO2 on a dry basis and at least one other of the streams contains more than 90 mol% CO2 on a dry basis.

[0004] Streams with different CO2 compositions are found in many processes. Streams with high CO2 concentrations are often produced by well-known units, such as an amine scrubber on synthesis gas to remove CO2 upstream of a cryogenic carbon monoxide separation.

[0005] High concentration streams are also produced by technologies operating on flue gases, such as amine washing or are produced directly by the upstream process by partial or complete oxycombustion.

[0006] At the same time as high concentration streams are produced, streams containing less CO2 than these are often available in the same geographical area or industrial process.

[0007] The following examples can be cited:

[0008] [Tab 1] More concentrated stream (% mol CO2 dry basis) Less concentrated stream (% mol CO2 dry basis) SMR Amine wash sized by available residual heat (>95%) Gas sent to stack by SMR (15%-25%) Refinery Amine wash (>95%) Fluidized catalytic cracking (FCC) tail gas (15%-25%) Or Reheat furnace (10-20%CO2) Cement plant Amine wash sized by available residual heat (>95%) - Oxy-fuel combustion for pre- Main stack (15%-35%) Dedicated stack for rotary kiln (10%-25%) Calciner / separate calciner or not (>60%) - Calix process (>90%) Lime plant Oxy-combustion with parallel flow regenerative kiln (PRFK) (>60%) Parallel flow regenerative kiln with cooling air extraction (>40%) Rotary drum kiln, axial kiln or PRFK stack (15%-25%) Steel mill Amine scrubbing of DRI reactor gas (>95%) or other steel mill gas (e.g. blast furnace gas) PSA residue on blast furnace gas Fuel heating waste gas (15%-30%) Or blast furnace gas (15-30%)

[0009]

[0010]

[0011]

[0012]

[0013] The above examples are not exhaustive and can even be crossed in an industrial basin (for example a flow coming from a cement plant, another coming from a lime factory or an SMR...) Streams with different CO2 concentrations can be treated by pooling certain parts of the treatment, preferably allowing CO2 recovery rates of more than 92 mol%, or even more than 95 mol% for low concentration streams and rates of up to 99 mol% for high concentration sources. For example, for a gaseous CO2 source containing 15-25 mol% CO2 from a stack and a gaseous CO2 source containing more than 95 mol% CO2 from an amine scrubber, the gas containing between 15 and 25 mol% CO2 can be scrubbed by adsorption ((V)PSA), permeation, partial condensation and / or distillation to form a CO2-enriched gas and: • the CO2-enriched gas and the gas containing more than 95% mol of CO2 can be compressed together, the gas containing more than 95% mol having been dried upstream of the common compression, • CO2-enriched gas and gas containing more than 95%mol of CO2 can be compressed and dried together. Gas containing 15-25 mol% CO2 can be separated by partial condensation and / or distillation to produce a liquid. At the same time the gas produced by amine washing can be liquefied independently.

[0014] The gas containing 15-25 mol% CO2 can be separated by adsorption ((V)PSA), permeation, partial condensation and / or distillation to produce a CO2-enriched gas which is liquefied in the same liquefier as the gas produced by amine scrubbing.

[0015] Alternatively the gas produced by amine washing can be dried and compressed and then sent to the partial condensation and / or distillation step fed with the gas containing 15-25 mol% CO2 to produce a common flow of liquid CO2.

[0016] For example, the gas containing 15-25 mol% CO2 can be a residual gas from SMR and the gas containing more than 95 mol% CO2 can be produced by amine scrubbing installed on the synthesis gas (typically upstream of cryogenic CO capture).

[0017] For other applications, CO2-containing streams may be co-produced by oxycombustion and air combustion. In this case, oxycombustion produces a gas stream containing 50-97 mol% CO2 while air combustion produces a gas stream containing between 15-35 mol% CO2.

[0018] Each flow can be treated independently to produce two CO2-enriched gaseous products.

[0019] Otherwise the two independently treated flows can be compressed by a common compressor forming a single pressurized gas flow.

[0020] Alternatively each flow can be treated independently to produce two CO2-enriched gaseous products and the two gaseous products can be liquefied in a common liquefier.

[0021] According to the invention, an integrated method is proposed which is of particular interest for the case where two flows are produced, a first flow containing a first percentage of CO2 and the second flow containing a second percentage of CO2 greater than the first percentage.

[0022] It applies to the case where the first flow is separated in a preconcentration unit, for example pre-concentration by adsorption in an adsorption unit, producing a gas enriched in CO2 compared to the first flow and the gas enriched in CO2 is separated by partial condensation and / or by distillation.

[0023] The second flow is separated by partial condensation and / or distillation, producing a CO2-enriched fluid and a CO2-depleted fluid. To recover the CO2 present in the CO2-depleted fluid, it is recycled to be separated in the preconcentration unit used to separate the first flow.

[0024] This brings significant advantages, by allowing to increase the overall CO2 yield. In addition, it allows to reduce the cost of the installation by eliminating the membranes or the dedicated CO2 PSA usually used to recover the CO2 in the CO2-depleted fluid. It becomes possible to use a unit downstream of the recycle to the preconcentration unit operating at low temperature to separate by partial condensation and / or distillation and / or solidification to produce a fluid containing at least 90% mol CO2 whereas usually such concentrations are not achievable with good efficiency.

[0025] According to an object of the invention, an integrated separation process is provided in which:

[0026] i) a first flow containing a first percentage of CO2 as well as oxygen and optionally water is compressed, optionally dried in a first drying unit, separated in a pre-concentration unit (P), for example by adsorption in an adsorption unit, producing a gas enriched in CO2 and depleted in oxygen compared to the first flow and the gas enriched in CO2 is separated by partial condensation and / or by distillation and / or by solidification in a first separation unit producing a fluid containing at least 95 mol% CO2 and at least a first fluid depleted in CO2

[0027] ii) a second flow contains a second percentage of CO2 greater than the first percentage as well as oxygen and water, the second flow is compressed, dried in a second drying unit, separated by partial condensation and / or by distillation and / or by solidification in a second separation unit, the second separation unit producing a CO2-enriched fluid containing at least 90 mol% of CO2 and depleted in oxygen as well as a second CO2-depleted and oxygen-enriched fluid and

[0028] iii)

[0029] a) wherein the first separation unit and the second separation unit have a common end portion where partial condensation and / or distillation and / or solidification takes place or

[0030] b) The final part of the first separation unit being the second separation unit.

[0031] According to other optional aspects: • a gas containing at least 80 mol% CO2 is sent from the first separation unit to the common final part or to the final part which is the second separation unit. • a fluid containing at least 80 mol% CO2 is sent from an initial part of the second separation unit to the common final part. • a fluid containing at least 80 mol% CO2, or even at least 90 mol% CO2 is sent from the second drying unit to the second separation unit. • to recover the CO2 present in the second fluid depleted in CO2, this is sent at least in part

[0032] a) upstream of the pre-concentration unit and / or,

[0033] b) downstream of the pre-concentration unit. • the second CO2-depleted fluid is separated in the preconcentration unit. • the first and / or second flow contains nitrogen, nitrogen oxide or carbon monoxide. • the pre-concentration unit separates the first flow and possibly the fluid depleted in CO2 by adsorption, for example by pressure shift, or by permeation. • the first flow contains less than 50% mol CO2 on a dry basis, preferably less than 35% or even less than 30% mol CO2 on a dry basis. • the CO2-enriched gas contains more than 50% mol CO2 on a dry basis, preferably more than 90% mol CO2 on a dry basis. • the second flow contains at least 50% mol CO2 on a dry basis, more than 70% mol CO2 on a dry basis, or even at least 90% CO2 on a dry basis. • the difference between the first percentage and the second percentage of CO2 on a dry basis is at least 20%, or even at least 40%. • the second flow is dried, for example at compressed atmospheric pressure, and then separated in the first or second separation unit. • the second CO2-depleted fluid is sent at least partly upstream of the pre-concentration unit, possibly by mixing it directly with the first flow, and the CO2-enriched gas contains less of the lighter constituent than a residual gas from the pre-concentration unit. • the second CO2-depleted fluid is sent at least in part to be mixed under pressure with the CO2-enriched gas coming from the preconcentration unit after at least one step of compression of the CO2-enriched gas. • the first CO2-depleted fluid is mixed with the second CO2-depleted fluid. • a gaseous mixture formed by mixing the first and second CO2-depleted fluids is expanded in a turbine. • a gas mixture formed by mixing the first and second CO2-depleted fluids serves as regeneration gas in the preconcentration unit which operates by adsorption. • a fluid containing at least 95% mol CO2 from the first separation unit is sent to separate in the second separation unit. • the second fluid depleted in CO2 and enriched in oxygen is separated in the first separation unit. • the second fluid depleted in CO2 and enriched in oxygen is mixed and compressed with a gas to be separated in the first separation unit. • the second fluid depleted in CO2 and enriched in oxygen is mixed and compressed with the gas enriched in CO2 and depleted in oxygen to be separated in the first separation unit. • the second fluid depleted in CO2 and enriched in oxygen is mixed with the compressed gas enriched in CO2 and depleted in oxygen to be separated in the first separation unit. • the second fluid depleted in CO2 and enriched in oxygen is mixed with a separated gas in the first separation unit.

[0034] According to another object of the invention, there is provided an integrated separation apparatus comprising a first compressor, optionally a first drying unit, a pre-concentration unit, a first separation unit, a second compressor, a second drying unit, a second separation unit, a pipe for sending • a first flow containing a first percentage of CO2 as well as oxygen and possibly water to the first compressor to be compressed, means for sending the compressed flow, possibly dried, into the first drying unit, to separate in the preconcentration unit, for example by adsorption in an adsorption unit, producing a gas enriched in CO2 and depleted in oxygen compared to the first flow, means for sending the gas enriched in CO2 to separate by partial condensation and / or by distillation and / or by solidification in the first separation unit producing a fluid containing at least 95 mol% CO2 and at least a first fluid depleted in CO2, a pipe for sending • a second flow contains a second percentage of CO2 greater than the first percentage as well as oxygen and water to the second compressor, means for sending the second compressed flow to be dried in the second drying unit, means for sending the second dried flow to be separated by partial condensation and / or by distillation and / or by solidification in the second separation unit, the second separation unit being capable of producing a CO2-enriched fluid containing at least 90 mol% of CO2 and depleted in oxygen as well as a second CO2-depleted and oxygen-enriched fluid

[0035] a) wherein the first separation unit and the second separation unit have a common end portion where partial condensation and / or dis-

[0036]

[0037]

[0038]

[0039]

[0040]

[0041] tillation and / or solidification or b) The final part of the first separation unit is the second separation unit. According to other optional aspects: • the apparatus comprises means for sending in which a gas containing at least 80 mol% of CO2 from the first separation unit to the common final part or to the final part which is the second separation unit. • the apparatus comprises means for sending a fluid containing at least 80 mol% of CO2 from an initial part of the second separation unit to the common final part. • the apparatus comprises means for sending a fluid containing at least 80 mol% of CO2, or even at least 90 mol% of CO2 is sent from the second drying unit to the second separation unit. • the first and second flows both come from different processes operated within the same steelworks, the same lime plant, the same cement plant, the same refinery or the same reformer. • the common final part is connected to an initial part of the first separation unit and to an initial part of the second separation unit in order to receive a fluid to be separated from each of the separation units. Preferably, the apparatus does not include a first drying unit. The device may not include a pre-concentration unit between the second compressor and the second drying unit. The apparatus may not include a preconcentration unit between the second drying unit and the second partial condensation and / or distillation and / or solidification separation unit. Among the optional features of the invention: • the first flow comes from a steel mill • the first flow is a waste gas from fuel heating, for example from a steelworks • the first flow is blast furnace gas • the first flow comes from a lime factory • the first flow comes from a rotary drum kiln, an axial kiln or a PRFK chimney • the first flow comes from a cement plant • the first flow comes from the main chimney of a cement plant or from the chimney dedicated to the rotary kiln of a cement plant • the first flow comes from a refinery • the first flow is a residual gas from fluidized bed catalytic cracking or comes from a refinery reheating furnace • the first flow is a gas sent to the chimney of an SMR • the first flow contains on a dry basis between 15 and 25% mol of CO2, between 10 and 20 mol% CO2, between 15 and 35 mol% CO2, between 10 and 25% CO2 • The second flow contains on a dry basis more than 90% mol of CO2, or even more than 95% mol of CO2 • The second flow comes from an amine wash, for example treating a gas from a refinery or a reformer or a cement plant or a steel mill (for example DRI reactor gas or blast furnace gas) • the second flow comes from oxycombustion, for example from oxycombustion from a lime plant for precalciner or calciner • the second flow comes from a Calix process • the second flow is a PSA waste product having separated, for example, blast furnace gas • the second flow comes from a lime factory • the second flow comes from an oxycombustion with a regenerative flow furnace parallel (PRFK) • the first flow comes from a parallel flow regenerative furnace with extraction of cooling air • the first and second flows both come from the same steel mill, the same lime plant, the same cement plant, the same refinery or the same reformer (for example SMR) • the first and second flows both come from different processes operated within the same steelworks, the same lime plant, the same cement plant, the same refinery or the same reformer (for example SMR). • both the first and second flows come from a steel mill, lime plant, cement plant, refinery or reformer (e.g. SMR) • the first flow comes from a steel mill or a lime plant or a cement plant or a refinery or a reformer (e.g. SMR) and the second gas comes from another unit which is a steel mill or a lime plant or a cement plant or a refinery or a reformer (e.g. SMR).

[0042] The invention will be described in more detail with reference to the figures in which:

[0043] [Fig-1] illustrates a method according to the invention.

[0044] [Fig.2] illustrates a method according to the invention.

[0045] [Fig-1] illustrates a method according to the invention in which a first flow 1 containing less than 50 mol% CO2 on a dry basis, for example between 15 and 25 mol% CO2 on a dry basis is separated in a first apparatus A ending with a step of partial condensation and / or distillation and / or solidification to produce a fluid, here a liquid containing at least 95% CO2.

[0046] The first apparatus A comprises a compressor IC, a drying unit 1D, a pre-concentration unit P, a compressor 1E and a unit for separation by partial condensation and / or distillation and / or solidification 1F. The drying unit D can be integrated into the pre-concentration unit P.

[0047] The first flow 1 also comprises oxygen, water and optionally at least one component which is nitrogen, a nitrogen oxide or carbon monoxide.

[0048] The first gas can come from: • a steelworks, • a lime factory, • a cement plant, • a refinery.

[0049] The first gas may be a waste gas from fuel heating, for example from a steelworks, a blast furnace gas.

[0050] The first gas may come from a rotary drum kiln, an axial kiln or a PRFK chimney of a lime plant.

[0051] The first gas may come from the main chimney of a cement plant or from the chimney dedicated to the rotary kiln of a cement plant.

[0052] The first gas may be a residual gas from fluidized bed catalytic cracking or comes from a reheat furnace of a refinery.

[0053] The first gas may be a gas sent to the stack of an SMR.

[0054] The first gas contains on a dry basis between 15 and 25 mol% of CO2, between 10 and 20 mol% of CO2, between 15 and 35 mol% of CO2, between 10 and 25% of CO2.

[0055] The first flow 1 is compressed by the compressor IC and dried in the drying unit 1D. The condensed water 5 in the compressor IC and the water 7 removed in the drying unit 1D are removed as condensate 9.

[0056] The first compressed and dried flow 10 is separated in the preconcentration unit P, which can operate by adsorption, for example by pressure switching or by permeation. The first flow 10 is separated forming a gas 11 enriched in CO2 and depleted in oxygen compared to the first flow. In the case of separation by adsorption, this gas 11 constitutes the waste product at low pressure. The gas 11 enriched in CO2 is compressed in a compressor 1E forming a compressed CO2-enriched gas 13 which is separated by partial condensation and / or by distillation and / or solidi fication in a first separation unit 1F producing a fluid or a solid 19 containing at least 80 mol% CO2, or even at least 90 mol% CO2.

[0057] A second flow 2 comprises at least 50 mol% CO2 on a dry basis, preferably at least 70 mol% CO2 on a dry basis and is separated in the apparatus B. It also comprises oxygen, water and optionally at least one component which is nitrogen, a nitrogen oxide or carbon monoxide. The second flow 2 contains in certain cases between 70 and 85 mol% of CO2 on a dry basis. The second flow 2 contains in certain cases at least 90%, or even at least 95 mol% of CO2 on a dry basis.

[0058] The second flow comes for example from an amine wash, for example treating a gas coming from a refinery or a reformer or a cement plant or a steelworks (for example DRI reactor gas or blast furnace gas).

[0059] The second gas comes for example from oxycombustion, for example from oxycombustion of a lime plant for precalciner or calciner.

[0060] The second gas comes for example from a Calix process in a cement plant. This process works by heating the limestone via a special steel reactor. This makes it possible to separate and capture the pure CO2 when it is released from the limestone, and therefore to keep the exhaust gases from the kiln isolated.

[0061] The second gas may be a PSA waste product having separated, for example, a blast furnace gas.

[0062] The second gas may come from a lime factory.

[0063] The second gas can come from oxycombustion with a parallel flow regenerative furnace (PRFK).

[0064] The second gas can come from a parallel flow regenerative furnace with extraction of cooling air.

[0065] The first and second gases may both come from the same unit, which may be a steel mill, a lime plant, a cement plant, a refinery or a reformer (for example SMR).

[0066] The second flow 2 is compressed in a compressor 2C, condensing the water 105 it contains and the partially dried flow 102 is dried in a drying unit 2D, for example at atmospheric pressure, forming a dried flow 104 and water 107. The condensates 109 formed by mixing the flows 105, 107 are removed.

[0067] The second dried flow 104 is sent as flow 113 to a unit for separation by partial condensation and / or distillation and / or solidification 2F. A fluid 129, which may be a gas or liquid, is produced containing at least 80 mol% CO2. The unit 2F also produces a flow 123 depleted in CO2 and enriched in O2. To recover the CO2 contained in the flow 123, the latter can be sent to the unit M to be separated by adsorption and / or permeation forming a flow 125 and a flow 127.

[0068] The apparatus B comprises two sections for separation by partial condensation and / or distillation and / or solidification 2F, 2G, as well as possibly a unit M for separation by permeation or adsorption.

[0069] A CO2-depleted and oxygen-enriched fluid 121 is sent from the unit 2F upstream or downstream of the preconcentration unit P. Rather than being injected directly upstream of the preconcentration unit P, the fluid 121 can be injected downstream therein, benefiting from the fact that the CO2-poor fluid 121 from the second unit 2G is typically at a pressure of around 30 bar.

[0070] The fluid 129 and the gas 19 of the unit A are separated in the second section 2G by partial condensation and / or distillation and / or solidification forming a liquid or a solid 119 rich in CO2, for example containing at least 95% mol CO2. The section 2G produces an oxygen-enriched gas 121. The gas 123 and / or the gas 121 is sent to the pre-concentration unit to be separated there.

[0071] [Fig.2] differs from [Fig.l] in that there is only one section for separation by partial condensation and / or distillation and / or solidification in the apparatus B, which is section 2F and by the presence of the compressor 2E. The gas 104 is compressed in the compressor 2E, sent as gas 113 into the unit for separation by partial condensation and / or distillation and / or solidification 2F forming a liquid 119 rich in CO2, the section 2F also being supplied by the gas 19 coming from the apparatus A which separates in the section 2F. A fluid 112 can be sent from the separation unit 2F to the compressor 2 E to be compressed there.

Claims

Claims

1. Integrated separation process in which i) a first flow (1) containing a first percentage of CO2 as well as oxygen and optionally water is compressed (IC), optionally dried in a first drying unit (1D), separated in a pre-concentration unit (P), for example by adsorption in an adsorption unit, producing a gas (11) enriched in CO2 and depleted in oxygen compared to the first flow and the CO2-enriched gas is separated by partial condensation and / or by distillation and / or by solidification in a first separation unit (1F, IG) producing a fluid containing at least 95 mol% CO2(19) and at least a first CO2-depleted fluid (15, 17) ii) a second flow (2) contains a second percentage of CO2 higher than the first percentage as well as oxygen and water, the second flow is compressed (2C), dried in a second drying unit (2D),separated by partial condensation and / or by distillation and / or by solidification in a second separation unit (2F, 2G), the second separation unit producing a CO2-enriched fluid (119) containing at least 90 mol% CO2 and depleted in oxygen as well as a second CO2-depleted and oxygen-enriched fluid (121) and iii) a) in which the first separation unit and the second separation unit have a common end portion (2G) where partial condensation and / or distillation and / or solidification takes place or b) The end portion (2F) of the first separation unit is the second separation unit.,

2. A method according to claim 1 wherein a gas containing at least 80 mol% CO2 is sent from the first separation unit (2F) to the common final part (2G) or to the final part which is the second separation unit.

3. A method according to claim 1 or 2 wherein a fluid containing at least 80 mol% CO2 is sent from an initial part (2F) of the second separation unit (2F) to the common final part (2G).

4. Method according to claim 1 or 2 in which a fluid (104) containing at least 80 mol% of CO2, or even at least 90 mol% of CO2 is sent from the second drying unit (2D) to the second separation unit (2F).

5. Integrated separation apparatus comprising a first compressor (IC), optionally a first drying unit (1D), a pre-concentration unit (P), a first separation unit (1F, IG), a second compressor (2C), a second drying unit (2D), a second separation unit (2F, 2G), a pipe for sending • a first flow (1) containing a first percentage of CO2 as well as oxygen and possibly water to the first compressor to be compressed (IC), means for sending the compressed flow, possibly dried, into the first drying unit (1D), to separate in the preconcentration unit (P), for example by adsorption in an adsorption unit, producing a gas (11) enriched in CO2 and depleted in oxygen compared to the first flow, means for sending the gas enriched in CO2 to separate by partial condensation and / or by distillation and / or by solidification in the first separation unit (1F, IG) producing a fluid containing at least 95 mol% CO2(19) and at least a first fluid depleted in CO2 (15, 17), a pipe for sending a second flow (2) containing a second percentage of CO2 greater than the first percentage as well as oxygen and water to the second compressor, means for sending the second compressed flow (2C) to be dried in the second drying unit (2D), means for sending the second dried flow to be separated by partial condensation and / or by distillation and / or by solidification in the second separation unit (2F, 2G), the second separation unit being capable of producing a CO2-enriched fluid (119) containing at least 90 mol% of CO2 and depleted in oxygen as well as a second CO2-depleted and oxygen-enriched fluid (121) a) in which the first separation unit and the second separation unit have a common final part (2G) where the partial condensation and / or the distillation and / or the solidification takes place or b) The final part (2F) of the first separation unit being the second separation unit.

6. Apparatus according to claim 5 comprising means for sending a gas containing at least 80 mol% of CO2 from the first se- preparation (2F) to the common final part (2G) or to the final part which is the second separation unit.

7. Apparatus according to claim 5 or 6 comprising means for sending a fluid containing at least 80 mol% of CO2 from an initial part (2F) of the second separation unit (2F) to the common final part (2G).

8. Apparatus according to claim 5 or 6 comprising means for sending a fluid (104) containing at least 80 mol% of CO2, or even at least 90 mol% of CO2 from the second drying unit (2D) to the second separation unit (2F).

9. Apparatus according to one of claims 5 to 8 wherein the common final part (2G) is connected to an initial part (1F) of the first separation unit and to an initial part (2F) of the second separation unit in order to receive a fluid to be separated (19, 129) from each of the separation units.

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