BE1030056B1 - Carbon Dioxide Separation Device - Google Patents

Abstract

The present invention relates to a carbon dioxide separation device 10, the carbon dioxide separation device 10 having an absorption device 20 and a desorption device 30, the absorption device 20 having a gas inlet 21 for the gas to be cleaned and a gas outlet 22 for the cleaned gas, the absorption device 20 has an absorption solvent inlet 23 and a solution outlet 24, the desorption device 30 having at least a first solution inlet 31, an absorption solvent outlet 32, a warm solvent inlet 33 and a carbon dioxide outlet 34, the solution outlet 24 being connected to the first solution inlet 31 via a first solution connection 40, the first solution connection 40 having a first heat exchanger 41, the absorption solvent outlet 32 being connected to the absorption solvent inlet 23 via an absorption solvent connection 50, the absorption solvent connection 50 having the first heat exchanger 41 such that the heat of the solvent stream is transferred to the solution stream, the absorption solvent connection 50 has a branch 51 to a warm solvent connection 52, the warm solvent connection 52 being connected to the warm solvent inlet 33, the warm solvent connection having a second heat exchanger 53, characterized in that the pressure of the solvent in the second heat exchanger 53 is increased by 0.2 bar to 5 bar is higher than the pressure in the desorption device 30 at the absorption solvent outlet 32.

Description

Carbon Dioxide Separation Device

The invention relates to a device for separating carbon dioxide from gases, in particular from exhaust gases.

In order to reduce man-made climate change, it is increasingly avoided

release carbon dioxide into the atmosphere. Rather, an attempt is made to

Separating carbon dioxide and either converting it afterwards or dumping it. A typical method for this is to scrub exhaust gases at about 25°C to 50°C with a basic solution, for example an amine solution. This amine solution acts as a solvent in which the carbon dioxide dissolves. The one containing the carbon dioxide

The solution is then heated and the carbon dioxide is converted back into the gas phase in a desorption step. This recovers the solvent and also produces a pure carbon dioxide gas stream. The carbon dioxide gas stream can then, for example, and purely by way of example, be deposited or fed to a methanol synthesis.

WO 2010/086 039 A1 discloses a method and a device for separating carbon dioxide from an exhaust gas from a fossil-fired power plant.

From the CN111203086A is a CO2 separation system with low

Energy consumption and low emissions known.

WO 2014/077 919 A1 discloses a device and a method for removing acidic gases from a gas stream and regenerating the absorbing solution.

From US 2017 / 0197175 A1 is an energy-efficient process for the extraction of acidic

Gas from a gas stream known.

From WO 2013 / 013 749 A1 is a heat recovery in absorption and

known desorption processes.

WO 2019 / 232 626 A1 describes a CO2 separation after combustion with a

heat recovery known.

What all systems for separating CO: have in common is that energy must be supplied to release the CO: from the solution again. For this purpose, heat is used at a high and thus comparatively valuable level.

The object of the invention is to provide a carbon dioxide separation device in which the overall process of absorption and desorption is energetically optimized.

This task is solved by the carbon dioxide separation device with the

Claim 1 specified features. Advantageous developments result from the dependent claims, the following description and the drawings.

The carbon dioxide separation device according to the invention has a

Absorption device and a desorption device. In the

The gas to be cleaned of carbon dioxide is introduced into the absorption device and the carbon dioxide is converted from the gas phase into the liquid phase by contact with a solvent, usually an amine solution. A solution is formed from the solvent with the carbon dioxide dissolved therein, which may be bound. This solution is transferred to the desorption device where the carbon dioxide is stripped out of the solution, thereby recovering the solvent and recirculating it back into the

Absorption device is transferred. Likewise, a carbon dioxide gas stream is obtained, which can be supplied for further use. This basic principle is already used in a large number of variations.

The absorption device has a gas inlet for the gas to be cleaned and a

Gas outlet for the cleaned gas. The gas to be cleaned can, for example

Waste gas from burning fossil fuels. The cleaned gas would then mostly be mainly nitrogen with a small remainder of carbon dioxide and possibly a greatly reduced proportion of carbon dioxide as a result of the combustion process

Oxygen. The cleaned gas can then be released into the atmosphere, for example, without releasing large amounts of carbon dioxide as a greenhouse gas. The

Absorption device usually has one or more mass transfer elements arranged between the gas inlet and the absorption solvent inlet.

The mass transfer elements serve to improve the liquid and the gaseous phase

3 BE2021/6009 to bring into contact, in particular to increase the surface area of the liquid phase.

Such mass transfer elements are known to the person skilled in the art and can be, for example, bubble trays, packing or structured packing,

The absorption device further includes an absorption solvent inlet and a

solution outlet. The absorption solvent inlet is usually at the top of the

Absorption device arranged, the solution outlet at the bottom

absorption device. Accordingly, the gas inlet is usually at the bottom and the

Gas outlet located on top so that gas and solvent flow countercurrently through the

Flow absorption device.

The desorption device has at least a first solution inlet, a

absorption solvent outlet, a warm solvent inlet and a carbon dioxide outlet. The solution outlet of the absorption device is connected to the first solution inlet of the desorption device via a first solution connection. The first

Solution connection has a first heat exchanger. This will make the

Solvent stream, which flows through the first solution connection, heated, so that the carbon dioxide present in the solution can be released again in the desorption device. The absorption solvent outlet of the desorption device is connected to the absorption solvent inlet of the absorption device via a

Connected absorption solvent compound. The solvent depleted of carbon dioxide in the desorption device flows back to the absorption solvent connection via the absorption solvent connection

absorption device. The absorbent solvent compound also has the first

heat exchanger on. As a result, the heat of the solvent stream in the

Transfer absorption solvent compound to the solution stream. The

Absorption solvent connection has a branch to a warm solvent connection. A partial flow of the solvent flow is thus branched off and fed into the

Warm solvent connection led. The warm solvent connection is with the

Connected to warm solvent inlet. The warm solvent compound has a second

heat exchanger on. As a result, additional energy can be introduced into the entire system. The desorption device usually has one or more

Mass transfer elements, which are arranged above and below the first solution inlet. The mass transfer elements serve to bring the liquid and the gaseous phase into better contact, in particular also to increase the surface area of the liquid phase. Such mass transfer elements are known to the person skilled in the art and can, for example, be bubble-cap trays or random packings,

According to the invention, the pressure of the solvent in the second heat exchanger is 0.2 bar to 5 bar higher than the pressure in the desorption device at the absorption solvent outlet.

A higher initial temperature can thus be achieved in the second heat exchanger, since the boiling point is increased by the increased pressure. This in turn means that the solvent has a higher temperature at the absorption solvent outlet and thus reaches the first heat exchanger at a higher temperature. As a result, it can either be made more compact or a higher outlet temperature can be achieved for the loaded solution stream from the first heat exchanger. The latter in turn leads to more efficient expulsion of the carbon dioxide from the solution.

In this case, the pressure of the solvent in the second heat exchanger can be adjusted due to the equipment. There are two exemplary and preferred embodiments for setting the pressure in a targeted manner using equipment. In a first exemplary and preferred

Embodiment of the invention, the pressure of the solvent in the second heat exchanger is thereby 0.2 bar to 5 bar higher than the pressure in the desorption device

Absorption solvent outlet that the second heat exchanger is arranged in height by at least 1m below the absorption solvent outlet, whereby the pressure in the second

Heat exchanger through the hydrostatic column of the solvent corresponding to the whole

Height difference is increased. In a second exemplary and preferred

Embodiment of the invention, the pressure of the solvent in the second heat exchanger is thereby 0.2 bar to 5 bar higher than the pressure in the desorption device

Absorption solvent outlet that a first pump for the second heat exchanger

Generation of the corresponding overpressure is arranged.

In a further embodiment of the invention between the second

Heat exchanger and the desorption device, arranged a pressure loss device, such as a control valve, a pinhole or a constriction.

With the pressure loss device, the desired overpressure is achieved in the second

Heat exchanger gas / steam set or maintained. This can prevent evaporation, if necessary, in the second heat exchanger.

The first solution inlet is preferably arranged in the central region of the desorption device.

In a further embodiment of the invention, the first solution connection 5 has an evaporation device downstream of the first heat exchanger in terms of flow. The evaporation device, also called pressure expansion tank, is used to allow the solution of the solution stream heated in the first heat exchanger to expand and partially evaporate. The liquid phase of the solution stream is thus separated from the gaseous phase of the solution stream in the evaporation device. The liquid phase is through the first solution compound in the

Desorption out. Abandonment of the liquid phase by the first

Solution connection and the first solution inlet is preferably between two

mass transfer elements. The desorption device further has a vapor inlet and the evaporation device has a vapor outlet. The vapor outlet of the evaporation device and the vapor inlet of the desorption device are for

Transfer of the gaseous phase associated with a gas solution compound.

The steam inlet is particularly preferably arranged in the lower region of the desorption device. Preferably no mass transfer elements are arranged in the lower area. This optimizes the energetic management of the overall process.

In a further embodiment of the invention branches between the

Absorption device and the first heat exchanger of the first

Solution compound from a second solution compound. The second solution connection leads directly to the top of the desorption device. Direct means in this

Connection without a heat exchanger or the like. If necessary, a (flow control) valve can be arranged here. Thus, the loaded with carbon dioxide

Solution itself used to cool the gas stream exiting the desoption device. As a result, what remains is that of the first heat exchanger and the second

Heat exchanger and the heat supplied to the desorption device in the

Desorption device and in the solvent and is not released to a cooling medium.

The carbon dioxide separation device according to the invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawings.

Fig. 1 first embodiment

Fig. 2 second embodiment

The representations shown are purely schematic and serve to illustrate the invention. Equal parts of the various embodiments are for

Provided with the same numbers for simplification.

In Fig. 1 a first embodiment of a carbon dioxide according to the invention

Separation device 10 shown. The carbon dioxide separation device 10 is used, for example, to separate the carbon dioxide from an exhaust gas stream, which in the

Gas inlet 21 enters and greatly depleted in carbon dioxide at the gas outlet 22 exits again. In the absorption device 20, this gas flow is countercurrent with a

solvent, usually an amine solution, so that the carbon dioxide in

solution works. This solution exits the absorption device at the solution outlet 24 and is pumped through the first solution connection 40 by a second pump 46 . The first solution compound 40 has a first heat exchanger 41 in which the solution flow is heated by the solvent flow of the absorption solvent compound 50 . The first heat exchanger 41 downstream is a

Evaporation device 42, in which the solution can partially pass into the gas phase. The liquid phase of the solution stream is further through the first

Solution connection 40, for example by means of a third pump 47 through the first

Solution inlet 31 promoted in the desorption device 30. That in the

Evaporation device 42 resulting gas / vapor is through the vapor outlet 43 in the gas solution connection 44 and through this via the vapor inlet 35 in the

Desorption device 30 out. The steam inlet 35 is preferably located at the lower end, the bottom, of the desorption device 30.

In the desorption device 30 the carbon dioxide is thermally removed from the solution and discharged via the carbon dioxide outlet 34 . This carbon dioxide stream can then be fed, for example, either to a further reaction or to landfill. The solvent freed from carbon dioxide collects at the bottom of the

Desorption device 30 and is through the absorption solvent outlet 32 of

Absorption solvent compound 50 supplied. The solvent flow is here in the first

Heat exchanger 41 from its thermal energy to the solution stream. For example

/ BE2021/6009 by means of a fourth pump, the solvent flow passes via a third heat exchanger 55 through the absorption solvent inlet 23 into the absorption device.

From the solvent flow in the absorption solvent connection 50, a partial flow branches off at the branch 51, which flows through the warm solvent connection 52 via the second

Heat exchanger 53 is conveyed back into the desorption device 30 in particular in vapor form or as a vapor/liquid mixture through the warm solvent inlet 33 . Via the second heat exchanger 53, the energy required for expelling the

Carbon dioxide from the solution fed to the system. Here is the second

Heat exchanger 53 arranged, for example, 3.5 m below the absorption solvent outlet 32, so that an overpressure of about 0.35 bar is set by the water column. As a result, the partial solvent flow can be heated to a higher temperature in the second heat exchanger 53, which in turn means that the

Inlet temperature of the guided through the absorption solvent connection 50

Solvent flow before the first heat exchanger 41 is increased accordingly.

The second embodiment shown in FIG. 2 differs from the first embodiment shown in FIG. 1 in that the pressure in the second

Heat exchanger 53 is not reached by a height difference, which reduces the overall height, but by a first pump 54.

Numeral 10 carbon dioxide separation device 20 absorption device, 21 gas inlet 22 gas outlet 23 absorption solvent inlet 24 solution outlet

Desorption device 30 31 first solution inlet 32 absorption solvent outlet 33 warm solvent inlet 34 carbon dioxide outlet

steam inlet

40 first solution connection 41 first heat exchanger 42 evaporation device 43 vapor outlet 44 gas solution connection

45 second solution compound 46 second pump 47 third pump 50 absorption solvent compound

51 branch 52 hot solvent connection 53 second heat exchanger 54 first pump 55 third heat exchanger

Claims (6)

patent claims 1. Carbon dioxide separation device (10), wherein the carbon dioxide separation device (10) has an absorption device (20) and a desorption device (30), the absorption device (20) having a gas inlet (21) for the gas to be cleaned and a gas outlet ( 22) for the cleaned gas, wherein the absorption device (20) has an absorption solvent inlet (23) and a solution outlet (24), wherein the desorption device (30) has at least a first solution inlet (31), an absorption solvent outlet (32), a warm solvent inlet ( 33) and a carbon dioxide outlet (34), the solution outlet (24) being connected to the first solution inlet (31) via a first solution connection (40), the first solution connection (40) having a first heat exchanger (41), the The absorption solvent outlet (32) is connected to the absorption solvent inlet (23) via an absorption solvent connection (50), the absorption solvent connection (50) comprising the first heat exchanger (41) such that the heat of the solvent stream is transferred to the solution stream, the absorption solvent connection (50) a branch (51) to a warm solvent connection (52), the warm solvent connection (52) being connected to the warm solvent inlet (33), the warm solvent connection having a second heat exchanger (53), characterized in that the pressure of the solvent in the second heat exchanger (53) is 0.2 bar to 5 bar higher than the pressure in the desorption device (30) at the absorption solvent outlet (32). 2. Carbon dioxide separation device (10) according to claim 1, characterized in that the pressure of the solvent in the second heat exchanger (53) is thereby 0.2 bar to 5 bar higher than the pressure in the desorption device (30) at the absorption solvent outlet (32 ) that the second heat exchanger (53) is located at least 1 m below the absorption solvent outlet (32) so that the pressure is generated by the hydrostatic pressure of the solvent. 3. Carbon dioxide separation device (10) according to claim 1, characterized in that the pressure of the solvent in the second heat exchanger (53) characterized by 0.2 bar to 5 bar higher than the pressure in the desorption device (30) at the absorption solvent outlet (32), that upstream of the second heat exchanger (53) a first pump (54) is arranged to generate the overpressure. 4. Carbon dioxide separation device (10) according to one of the preceding claims, characterized in that the first solution connection (40) downstream of the first heat exchanger (41) has an evaporation device (42), in which the liquid phase of the solution stream is separated from the gaseous phase of the solution stream, the liquid phase being conducted through the first solution connection (40) into the desorption device (30), the desorption device (30) having a vapor inlet (35), the evaporation device having a vapor outlet (43 ) wherein the vapor outlet (43) and the vapor inlet (35) are connected to a gas dissolving connection (44) for transferring the gaseous phase. 5. Carbon dioxide separation device (10) according to claim 4, characterized in that the steam inlet (35) is arranged in the lower region of the desorption device (30). 6. Carbon dioxide separation device (10) according to one of the preceding claims, characterized in that between the absorption device (20) and the first heat exchanger (41) a second solution connection (45) branches off from the first solution connection (40), the second solution connection (45) leads directly into the head of the desorption device (30).