EP2498896A1

EP2498896A1 - Method and apparatus for gas scrubbing

Info

Publication number: EP2498896A1
Application number: EP10778564A
Authority: EP
Inventors: Dieter Mihailowitsch; Eckard Steinmetz
Original assignee: Linde KCA Dresden GmbH
Current assignee: Linde Engineering Dresden GmbH
Priority date: 2009-11-10
Filing date: 2010-11-04
Publication date: 2012-09-19
Also published as: US20120304859A1; AU2010318355A1; WO2011057741A1; DE102009052640A1; ZA201202863B; CA2780452A1

Abstract

The invention relates to a method and apparatus for carrying out gas scrubbing, wherein gas is led through a washing column (T) from bottom to top, and washing material is led through the column (T) from top to bottom. At least two washing sections (WS1, WS2) are arranged one above the other in the washing column (T), of which the upper section (WS2) is delimited at the bottom by a riser base (K). At least a portion of the washing material loaded in the upper washing section (WS2) is drawn off at a draw-off point (A) provided in the area of the riser base (K) and is introduced into the lower washing section (WS1) as washing material at an introduction point (E) provided in the area of the lower washing section (WS1). A heat exchanger device (6) is interposed after the draw-off point (A) and before the introduction point (E) in the flow direction. The flow through the heat exchanger (6) is ensured solely by the hydrostatic pressure of the washing material, which results from the difference in height between the draw-off point (A) and the introduction point (E). A pump is dispensed with in this case.

Description

description

Process and apparatus for gas scrubbing

The invention relates to a device for carrying out a gas scrubbing, in which gas from bottom to top and detergent from top to bottom by a

Washing column are performed, with at least two laundry sections in the

Washing column are arranged one above the other, of which the upper is bounded below by a chimney tray, from which at least a part of the detergent loaded in the upper washing section deductible at a provided in the chimney flue outlet and as detergent at an opening provided in the lower washing section discharge point in the lower washing section can be introduced, wherein in the flow direction behind the take-off point and before the

Einleitungsstelle a heat exchange device is interposed, and a method for operating the device. Such devices are used in particular for physical gas scrubbing. Physical gas scrubbing exploits the ability of liquids to absorb gaseous substances and hold them in solution without chemically binding the gases. How well a gas is absorbed by a liquid is expressed by the solubility coefficient: the better the gas dissolves in the liquid, the greater its solubility coefficient. The solubility coefficient is temperature dependent and increases i. Gen. with falling temperature. Therefore, the liquid detergent is often used to increase the solubility coefficient, e.g. cooled by heat exchange with a refrigerant before washing. For example, amine-containing detergents are used to remove carbon dioxide

(C0 ₂ ) from flue gases used to reduce the release of environmentally harmful substances to the environment. The washed-out carbon dioxide can be compressed and, if necessary, pressed into the ground after further treatment or put to another use. In this way, for example, a nearly carbon dioxide emission-free operation of coal power plants is possible.

According to the prior art, a flue gas C0 ₂ scrubbing is carried out in a scrubbing column in which at least two washing sections are arranged one above the other and are separated from each other by a chimney tray, wherein in the lower section of the first and in the upper section of the second washing step take place. Such a washing column has in its lower part via a device for supplying the flue gas to be washed and at its head via a device for the withdrawal of the washed flue gas. Furthermore, it has facilities for supplying unladen detergent at the top of the column, for the withdrawal of loaded detergent from the chimney tray, for the supply of laden W schmittel in the lower washing section and for the withdrawal of the bottom product from the sump space. The loaded detergent, which collects in the chimney tray, is withdrawn from this and at least partially promoted by means of a pump to a heat exchange device in which it is cooled to increase the solubility coefficient.

Finally, the cooled detergent is introduced into the lower washing section.

In this known method so the flow through the

Heat exchange device with the detergent guaranteed by a pump. For this purpose, in addition to the actual pump, a pump drive, a pump control and a liquid template within the wash column are necessary, which is significant

Investment and operating costs required. In addition, there is the risk of malfunctions due to pump failures. Since this is usually not allowed, the pump must therefore be redundant. Furthermore, the cost of regular maintenance of the pump assembly is taken into account.

Object of the present invention is therefore to provide a device of

generic type and to provide a method for their operation, with which at significantly reduced cost, the risk of malfunction can be largely eliminated.

The object is achieved by the device according to the invention in that the withdrawal point is arranged so far above the point of introduction that the hydrostatic energy is sufficient only to flow through the heat exchange device and for introducing the detergent into the lower washing section.

The invention is based on the idea to replace the pump energy by hydrostatic energy. For this purpose, a height difference is set between the take-off point and the point of introduction of the detergent, which is a hydrostatic pressure of the detergent has the consequence, for a flow through the

Heat exchanger device and sufficient for the introduction of the detergent in the lower washing section. The driving force for the detergent is therefore no longer generated by the pump, but solely by the hydrostatic energy due to the difference in height between the discharge and discharge point. Usually, according to the prior art, a pump is used in order to be free in the installation of the heat exchange device and on the other hand a higher

To allow pressure loss within the heat exchange device and its piping. Surprisingly, it was found with the invention that on the one hand a suitable installation of the heat exchange device can be realized without additional costs and on the other hand the additional costs of the lower allowable pressure loss more expensive heat exchange device are more than offset by the cost savings due to the elimination of the pump. Conveniently, the heat exchange device is outside the wash column. arranged and connected via lines on the one hand to the withdrawal point and on the other hand to the discharge point. In this case, the withdrawal point is arranged at a height above the point of introduction, from which a hydrostatic energy of the

Detergent results, with the pressure losses in the lines and in the

Heat exchange device can be overcome. In practice, the chimney tray in the wash column is designed so that at the trigger point of the lower

Washing section of certain detergent can form a static fluid pressure, which is sufficient to compensate for the pressure losses experienced by the detergent on its way from the chimney tray in the lower washing section. Because of the frictional losses in the ducts and the pressure losses caused by the heat exchanger, heights of several meters may result for the chimney tray. Preferably, the height difference between the take-off point and the point of introduction is about 2 to about 8 m. An advantageous embodiment of the invention provides that at least three, separated by fireplace floors washing sections are arranged in the washing column, wherein the withdrawal point for the detergent in the area of the lowest

Chimney tray and the introduction point for the detergent are arranged in the region of the lowest washing section and the heat exchange device between

Deduction point and discharge point is interposed. Such Embodiment can be used for example with advantage for amine scrubbing of flue gases.

Underneath these washing sections may optionally be additionally provided a pre-wash. In this case, the extraction point for the detergent in the range of the lowest above the prewash arranged chimney tray and the

Introduction point for the detergent provided in the area of the lowest above the pre-wash washing section. Basically, the invention is suitable for all gas scrubbing in which the loaded detergent withdrawn from an upper washing section and after a

Heat exchange to be initiated in a heat exchange device in a lower washing section. In particular, the invention is provided for physical gas scrubbing in which the withdrawn detergent is cooled in the heat exchange device to increase the solubility coefficient and introduced into the lower washing section.

The invention further relates to a method for carrying out a gas scrubbing in which gas from bottom to top and detergent from top to bottom are passed through the scrubbing column, wherein at least two washing sections in the

Washing column are arranged one above the other, of which the upper is bounded below by a chimney tray, from which at least a portion of the loaded in the upper washing section detergent withdrawn via a

Heat exchange device passed and introduced as a detergent in the lower washing section.

The method, the object is achieved in that the detergent is driven solely due to the hydrostatic energy through the heat exchanger to the lower washing section.

A preferred embodiment of the method according to the invention provides that of a carbon dioxide-containing flue gas using an amine-containing

Detergent at least a portion of the carbon dioxide is washed out. By the invention it is possible to dispense with the usual pump with drive, control and original volume, whereby both the investment and operating costs can be significantly reduced. In addition, the susceptibility is significantly reduced.

In the following, the invention will be explained in more detail with reference to embodiments schematically illustrated in the figures compared to the prior art. 1 shows a washing column with pump-driven intercooler after

State of the art

FIG. 2 shows a washing column with a gravity-driven intermediate cooler, FIG. 3 shows a washing column with an elevated level,

Gravity-driven intercooler

1 shows a washing column for flue gas C0 ₂ scrubbing according to the prior art, in which carbon dioxide-containing flue gas obtained, for example, in a coal-fired power plant, the carbon dioxide is largely removed by means of an amine-containing detergent in several washing sections. The leached carbon dioxide can be pressed in the background after appropriate, not shown in the figure, treatment or another use, eg as a feedstock for bioreactors (algae cultures) for fuel production, fed.

Via line 1, the flue gas to be purified is introduced into the wash column T and then flows upward through the lower washing section WS1. Detergent, which has already been used in the upper washing section WS2 for gas scrubbing, is collected in the chimney tray K, which closes the washing section WS2 down, and passed via lines 5 and 4 in the lower washing section WS1. The detergent flows in the lower washing section WS1 from top to bottom, and washes on its way out of the counter-current flue gas part of the

Carbon dioxide before it - now loaded with C0 ₂ and possibly other components - in the sump space S of the wash column T is collected. That already partially cleaned flue gas flows through the chimney tray K up to the top

Washing section WS2 in which it is further purified from carbon dioxide by countercurrent detergent regenerated at the head of the washing section WS2 via line 2. Via line 3, the purified flue gas is finally withdrawn from the wash column T.

To increase the solubility coefficient of the detergent, the scrubbing agent withdrawn from the scrubbing column via line 5 is cooled by heat exchange with a refrigerant in a heat exchanger 6, which is provided as a heat exchange device and is usually referred to as an intercooler. The cooled detergent is introduced via line 4 into the lower washing section WS1. The flow through the heat exchanger 6 is ensured by a pump 7.

The embodiment of the invention shown in Figure 2 differs from the prior art shown in Figure 1 in that the Durchströmurig of

Heat exchanger 6 is not guaranteed by a pump, but solely by the hydrostatic pressure of the withdrawn via line 5 from the fireplace floor K detergent. For this purpose, the withdrawal point A is disposed at a height above the discharge point E, which has a sufficient for overcoming the pressure loss in the lines 4 and 5 and in the heat exchanger 6 hydrostatic pressure result. In this case, the height difference between the withdrawal point A and the point of introduction E is in practice e.g. 2 to 8 m.

FIG. 3 shows a variant of the exemplary embodiment shown in FIG. 2, in which the heat exchanger 6 is arranged at an elevated level in order to prevent the heat exchanger

Pressure losses in the lines 4 and 5 and thus the necessary hydrostatic pressure, ie the height difference between the withdrawal point A and discharge point E to reduce.

Claims

claims

Apparatus for carrying out a gas scrubbing in which gas from bottom to top and detergent from top to bottom through a scrubbing column, wherein at least two washing sections (WS1, WS2) in the scrubbing column (T) are arranged one above the other, of which the upper down is bounded by a chimney tray (K), from which at least part of the detergent loaded in the upper washing section (WS2) is deposited at one in the region of

Chimney tray (K) provided withdrawal point (A) äbziehbar and provided as a detergent at one in the lower washing section (WS1)

Introductory point (E) in the lower washing section (WS1) can be introduced, wherein in the flow direction behind the take-off point (A) and before the discharge point (E) a heat exchange means (6) is interposed, characterized

characterized in that the withdrawal point (A) is arranged so far above the point of introduction (E), that the hydrostatic energy is sufficient only for the flow through the heat exchange device (6) and for introducing the detergent into the lower washing section (WS1).

Device according to claim 1, characterized in that the

Heat exchange device (6) outside the wash column (T) is arranged and is connected via lines (4,5) on the one hand to the withdrawal point (A) and on the other hand to the discharge point (E) and that the withdrawal point (A) at a level above the discharge point (E) is arranged, from which results in a hydrostatic energy of the detergent, with which the pressure losses in the lines (4,5) and in the heat exchange device (6) can be overcome.

Device according to one of claims 1 or 2, characterized in that in the wash column (T) is a physical gas scrubbing by means of a in the

Heat exchange device (6) cooled physical detergent

is feasible.

Device according to one of claims 1 to 3, characterized in that at least three, separated by fireplace floors washing sections in the washing column (T) are arranged, wherein the withdrawal point (A) for the detergent in the region of the lowest chimney tray (K) and the discharge point (E) are arranged for the detergent in the region of the lowest washing section (WS1) and the heat exchange device (6) between the withdrawal point (A) and discharge point (E) is interposed.

Method for operating a washing column (T) for carrying out a gas scrubbing, in which gas is passed from the bottom to the top and detergent from top to bottom through the scrubbing column (T), wherein at least two scrubbing sections (WS1, WS2) in the scrubbing column (T) are arranged one above the other, of which the upper is bounded below by a chimney tray (K), from which at least a part of the loaded in the upper washing section (WS2)

Detached detergent, passed through a heat exchange device (6) and introduced as a detergent in the lower washing section (6), characterized

characterized in that the detergent is driven solely by the hydrostatic energy through the heat exchanger (6) to the lower washing section (WS1).

A method according to claim 5, characterized in that from a

carbon dioxide-containing flue gas using an amine-containing detergent at least a portion of the carbon dioxide is washed out.