CO2 capture process by partial condensation and / or liquefaction and / or solidification

Abstract

Title: CO2 Capture Process by Partial Condensation and / or Liquefaction and / or Solidification In a CO2 capture process by partial condensation and / or liquefaction and / or solidification, a first cryogenic liquid (1) is continuously vaporized, a second cryogenic liquid (2) is intermittently vaporized, the first liquid vaporizing in a heater (ST) and the second liquid intermittently vaporizing in the heater. Abstract Figure: Single Figure

Description

Title of the invention: Method for capturing CO2 by partial condensation and / or liquefaction and / or solidification

[0001] Introduction

[0002] The present invention relates to a method for capturing CO2 by partial condensation and / or liquefaction and / or solidification.

[0003] CO2 capture processes by partial condensation and / or liquefaction and / or solidification sometimes include at least one washing column (for example a washing column for removing NO2). Usually, the liquid purge taken from the column bottom is vaporized in the main exchange line (typically in a plate and fin exchanger).

[0004] The processes for capturing CO2 by partial condensation and / or liquefaction and / or solidification also comprise a means for vaporizing the cryogenic liquid inventory of the process when the latter is stopped (for example before a defrosting phase, when all liquid must be evacuated from the capture apparatus).

[0005] The invention proposed here makes it possible to combine the two functions in a single piece of equipment.

[0006] State of the art

[0007] The use of a scrubbing column (for example the so-called DeNOx column for removing NO2) in CO2 capture processes is something already described. Typically, the liquid purge from this column is vaporized in the main exchange line (in a brazed aluminum exchanger). The person skilled in the art could also choose to vaporize this cryogenic liquid purge in a dedicated exchanger (water-operated shell and tube exchanger for example).

[0008] For cryogenic processes (CO2 capture, air separation) a means is conventionally used to vaporize the liquid inventory. The equipment known to those skilled in the art for performing this function are: steam ejector; electric ejector; shell & tube exchanger for water or water vapor; atmospheric canister.

[0009] In these processes, it is conventional to have a cooling water circuit and potentially a hot water circuit.

[0010] Problem solved by the invention

[0011] The invention makes it possible to combine in a single piece of equipment the continuous vaporization of a purge of cryogenic liquid concentrated in impurities and the punctual vaporization of the liquid inventory of the capture process.

[0012] Description of the invention

[0013] The invention mainly consists of using an exchanger allowing both vaporize cryogenic liquid continuously and to vaporize the liquid inventory of the cryogenic process punctually (function normally carried out by the vaporization means, for example, before a defrosting phase). This exchanger can be a water vapor, hot water or cooling water exchanger.

[0014] There are then different possible operating modes for this heater: • Normal operation: the cryogenic liquid purge (for example the purge from a washing column or the deconcentration purge from an exchanger, loaded with impurities) is continuously vaporized in the heater.

[0015] For CO2 capture processes, the liquid purge from the DeNOx column is therefore no longer vaporized in the main exchange line (typically in the main plate and fin exchanger). This has the advantage of being able to carry out vaporization at high temperature (between 20°C and 60°C) with a significant temperature difference (>30°C). This allows rapid vaporization, known as “flash” in English, to avoid the solidification of heavy compounds contained in the purge which concentrates during the vaporization of the CO2. • One-off operation: when you want to purge a cryogenic process of its liquid, it is necessary to vaporize this liquid. The gas resulting from this vaporization is sent to the atmosphere.

[0016] One possible configuration is to have a shell and tube exchanger operating on hot water or cooling water with a double bundle of tubes: one bundle for continuous purging and one bundle for the point purging function.

[0017] In the case where continuous vaporization and intermittent vaporization are carried out in the same circuit, a set of bypass lines makes it possible either to guide the vaporized cryogenic liquid in the process or to evacuate it to the atmosphere.

[0018] According to an object of the invention, there is provided a method for capturing CO2 by separating a gaseous mixture containing CO2 and at least one component lighter or heavier than CO2 by partial condensation and / or liquefaction and / or solidification producing a liquid (1) and at least punctually a fluid in which: i. A liquid is continuously vaporized, ii. A fluid is heated, or even vaporized or pseudovaporized, punctually, and iii. The liquid vaporizing in a heater and the fluid being heated, or even vaporizing or pseudo-vaporizing, punctually in the heater.

[0019] Preferably, a set of bypass lines allows either the vaporized liquid to be guided into the process or to be evacuated to the atmosphere.

[0020] Preferably, a set of bypass lines sends the vaporized liquid and / or the heated fluid to the process or to the atmosphere.

[0021] Preferably the heater is a shell and tube heat exchanger with two tube bundles, the liquid being sent to one bundle and the fluid being sent to the other bundle.

[0022] The invention will be described in more detail, with reference to the figure where:

[0023] [Fig-1] illustrates a method according to the invention. A method for capturing CO2 by se Preparation of a gaseous mixture containing CO2 and at least one component lighter or heavier than CO2 by partial condensation and / or liquefaction and / or solidification produces a first liquid which must be vaporized continuously and a second liquid 2 which must be vaporized punctually.

[0024] The first liquid may for example be the tank liquid of a washing column of the process (for example a washing column for removing NO2).

[0025] The second liquid 2 may be a liquid discharged from the process in preparation for a defrosting operation.

[0026] The first liquid 1 to be continuously vaporized is continuously supplied to a shell and tube heat exchanger ST of the two tube bundles type. The first liquid 1 is continuously supplied through the open valve VI to one bundle where it vaporizes by heat exchange with hot water. The second liquid 3 is punctually supplied to the other bundle through the open valve V2 and vaporizes in the other bundle of the exchanger ST. The liquid 2 is vaporized.

[0027] Liquid 1 and / or liquid 2 is sent in vaporized form to air A through open valve V4 and a pipe and / or to process P through open valve V3 and another pipe.

[0028] According to a variant, the second liquid 2 can be replaced by a supercritical fluid, for example CO2, which pseudo-vaporizes in the heater ST or by a gas to be heated, for example a CO2 purge.

Claims

Claims

1. Method for capturing CO2 by separating a gaseous mixture containing CO2 and at least one component lighter or heavier than CO2 by partial condensation and / or liquefaction and / or solidification producing a liquid (1) and at least occasionally a fluid in which: i. A liquid (1) is continuously vaporized, ii. A fluid (2) is heated, or even vaporized or pseudovaporized, in a punctual manner and iii. The liquid vaporizing in a heater (ST) and the fluid being heated, or even vaporizing or pseudovaporizing, in a punctual manner in the heater.

2. A method according to claim 1 wherein a set of bypass lines sends the vaporized liquid and / or the heated fluid to the process (P) or to the atmosphere (A).

3. A method according to claim 1 wherein the heater (ST) is a shell and tube heat exchanger with two bundles of tubes, the liquid (1) being sent to one bundle and the fluid (2) being sent to the other bundle.

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