GB2461547A

GB2461547A - Two-phase condenser

Info

Publication number: GB2461547A
Application number: GB0812136A
Authority: GB
Inventors: Inge Tronstad
Original assignee: Nebb Tech AS
Current assignee: Nebb Tech AS
Priority date: 2008-07-02
Filing date: 2008-07-02
Publication date: 2010-01-06
Anticipated expiration: 2028-07-02
Also published as: GB2461547B; GB0812136D0; DE102009026090A1

Abstract

The invention concerns a condensation apparatus and a method for the removal of a first substance from a gas mixture which is composed of the first substance in gaseous phase and at least one additional substance in gaseous phase. The condensation apparatus 10 comprises a condensation chamber 12 with an inlet 17 for the gas mixture and an outlet 18 such that a condensation space 14 is created between the inlet and the outlet. The condensation space comprises one or more condensation sections, where each condensation section comprises: - distributing means 23 for the distribution of the first substance, in the form of a spray, into the gas mixture, and - cooling means 37 arranged below the distributing means wherein a cooling medium is circulated. The condensation space is provided with collecting means 26 such that at least a portion of the first substance in liquid form can be collected and recirculated whereby the declining condensation temperature, as a result of declining partial pressure of the condensing component, is used to enhance condensation in the previous condensation steps.

Description

I

Two-phase condenser The present invention relates to a condensation apparatus and a method for the removal of a first substance from a gas mixture comprising the first substance and at least one additional substance.

The condensation apparatus can be used in processes where a gas mixture comprising substantially two components are to be cooled and one of the components is to be partly or completely condensed. A typical field of application would be where steam (i.e. water) needs to be separated from a mixture of carbon dioxide (C02) and steam (H20). A closely related example is the flue gas from an oxyfuel power process, comprising C02, H20 and a few percent of Ar, N2 and 02.

WO 02/100507 Al discloses a method for treating a gas which is contaminated by a noxious vapour where the contaminated gas is passed radially into a vortex chamber wherein the contaminated gas is exposed to cold droplets of the same substance as the noxious vapour and thereafter the contaminated gas is passed through an outlet in a generally upward direction. This design makes it unsuitable for two or more condensation sections within the same condensation chamber. Furthermore, the liquid noxious substance is cooled down in a chiller before being passed into the vortex chamber such that the temperature is close to the solidification temperature.

The noxious substance in liquid is atomized by directing two jets towards each other which makes it difficult to obtain an even distribution of droplets over the whole cross sectional area of the tank.

There is no indication in this publication that the contaminated gas is passed into the vortex chamber at or just above the dew point temperature, which is an important feature of the present invention. To the contrary, the method disclosed is a method for treating a gas contaminated with noxious gas from a hot working environment, the contaminated gas being passed through the vortex chamber.

The object of the present invention is therefore to provide a novel and efficient apparatus and method for the removal of a first substance from a gas mixture comprising two or more substances in gaseous phase, the gas mixture including said first substance.

This objective is achieved with a condensation apparatus as defined in claim 1, a method for separating a first substance from a gas mixture as defined in claim 11 and use of the condensation apparatus and the method for separating a first substance from a gas mixture as defined in claims 16 and 17 respectively. Further embodiments of the condensation apparatus is defined in the dependent claims 2-10 and further embodiments of the method for separating a first substance from a gas mixture is defined in claims 12-15.

The phrase "arranged above", as it is used in this application, should be understood to mean that the inlet and the outlet are located at different vertical levels, i.e. there is a vertical distance between the inlet and the outlet. However, the inlet or the outlet does not necessarily have to be arranged directly beneath the other.

Thus there is provided a condensation apparatus for the removal of a first substance from a gas mixture which is composed of the first substance in gaseous phase and at least one additional substance in gaseous phase. The condensation apparatus comprises a condensation chamber with an inlet for the gas mixture and an outlet, the inlet being arranged above the outlet such that a condensation space is created between the inlet and the outlet. Furthermore, the condensation space comprises one or more condensation sections where each condensation section comprises -distributing means for the distribution of the first substance, in the form of a spray, into the gas mixture, and -cooling means arranged below the distributing means wherein a cooling medium is circulated.

The condensation space may also be provided with collecting means arranged above the outlet for the collecting of at least a portion of the first substance in liquid form Furthermore, the condensation space may be provided with recirculation means recirculating at least a portion of the collected first substance in liquid form to the distributing means such that declining condensation temperature, as a result of declining partial pressure of the condensing component, is used to enhance condensation in the previous condensation step or steps.

The distributing means is preferably arranged such that the spray creates movement of the gas mixture around the cooling means. Furthermore, the introduction of the fine droplets of the spray into the gas mixture enhances the cooling of the gas mixture, and hence the condensation of the first substance in the gas mixture. This is due to the large surface area and lower temperature of the droplets.

The condensation chamber will normally be arranged in a vertical or a horizontal position. The inlet may be arranged above the outlet such that the gas mixture and the spray of the first substance in liquid form flow in the same direction. Another option is to arrange the outlet above the inlet such that the gas mixture and the spray flow in opposite directions. It would also be possible to arrange the inlet and the outlet such that the gas mixture flows in a substantially horizontal direction while the spray flows in a substantially vertical direction.

It would also be possible to arrange the condensation chamber in a slanting position.

In this case the spray will still flow in a substantially vertical direction.

Above, it is stated that the direction of flow of the spray of the first substance in liquid form is substantially vertical. The distributing means are arranged above the collecting means, which means that the spray in the end moves a certain vertical distance downwards. However, as the droplets leave the distributing means, most of the droplets will flow in a direction which is different from an absolute vertical direction and may be closer to a horizontal direction than a vertical direction. The droplets will, however, also have a downwards directed velocity component which will be the dominant component shortly after the droplets have left the distributing means. For the sake of simplicity it is therefore said that the spray (meaning the droplets of the spray) flows in a substantially vertical direction.

Preferably, the distributing means comprises at least one nozzle and a supply line for the supply of the first substance in liquid form to the at least one nozzle.

Normally a number of nozzles will be used forming a nozzle deck such that more or less the entire cross section of the condensation section will be covered with spray from the nozzles.

In a preferred embodiment of the invention, the condensation apparatus comprises means for recirculating at least a portion of the collected first substance in liquid form back to the distributing means. Thus the declining condensation temperature, as a result of declining partial pressure of the condensing componing, is used to enhance condensation in the previous condensation step or steps.

In an embodiment the collecting means comprises a collecting plate which covers substantially the entire cross section of the condensation chamber and a removal line. The collecting plate further comprises through-flow means such that the gas mixture can pass through the collecting plate while liquid is collected by the collecting plate, i.e. the gas mixture with any remaining first substance in gaseous phase, may be passed through the collecting plate to the following condensation section or to the outlet of the condensation chamber, while the liquid first substance remains on top of the collecting plate and is thereafter removed from the collecting plate through the removal line. The through-flow means could be a pipe socket surrounding a hole in the collecting plate and extending upwards from the bottom of the collecting plate. The height of the pipe socket should be made such that the collected liquid first substance does not overflow to the next section or to the bottom of the condensation chamber. The top of the pipe socket should be provided with a cover which is arranged such that the spray and the condensed liquid first substance do not fall into the pipe socket while the gas mixture is allowed to pass underneath the cover and through the pipe socket to the next condensation section.

The liquid first substance that is collected by the collecting plate, will be a mix of the liquid first substance that is sprayed into the gas mixture through the distributing means, and liquid first substance which has condensed from the gas mixture.

Alternatively the collecting means may comprise at least one receptacle and a removal line for the removal of liquid first substance from the at least one receptacle. Preferably a number of such receptacles are provided covering a substantial area of the cross sectional area of the condensation chamber. It would also be possible to provide receptacles in two vertically different levels where the receptacles on one level are horizontally displaced relative to the receptacles in the other level such that substantially the entire cross sectional area is covered by receptacles.

In a preferred embodiment of the invention each condensation section is provided with collecting means arranged below the cooling means of said condensation section.

If the inlet and the outlet is arranged so that the gas mixture flows in a substantially horizontal direction, the collecting means may quite simply be formed by the bottom of the condensation chamber which is then provided with at least one outlet to which the removal line is connected. The bottom may be arranged slanting slightly towards the outlet.

In a preferred embodiment of the invention the removal line is connected to a condensate tank and the supply line is connected to a pump which in turn is connected to the condensate tank such that the liquid first substance collected by the collecting means may be circulated back to the distributing means and sprayed into the gas mixture. If the condensation apparatus is provided with two or more removal lines, i.e. removal lines from several collecting means are provided, the removal lines are preferably connected such that there is only one removal line feeding condensate to the condensate tank. The condensate being fed to the condensate tank will normally comprise a mix of condensed first substance and the liquid first substance that has been sprayed into the condensation space.

The condensation tank should also be provided with an outlet so that the surplus of collected first substance in liquid form may be removed.

In a preferred embodiment the cooling means comprises at least one cooling element and a cooling fluid circulating line such that a cooling fluid may be circulated through the at least one cooling element. The circulating line connects the at least one cooling element with a supply of cooling fluid which may comprise a first storage means for cooling fluid. If the condensation space comprises two or more condensation sections, each condensation section being provided with one or more cooling elements, the circulating line preferably connects the cooling elements in each condensation section and may also connect cooling elements in different condensation sections such that the cooling fluid can circulate through all the cooling elements. Between different condensation sections the circulating line is preferably arranged outside the condensation chamber, but may obviously be arranged inside the condensation chamber if that is desirable, for instance if required because of space restrictions. After having circulated through the last cooling element the cooling fluid may be passed on to a second storage means for the cooling fluid, or alternatively back to the first storage means for cooling fluid.

From the second storage means the cooling fluid may be cooled down and thereafter fed directly back to the condensation space or to the first storage means for the cooling fluid.

An alternative may be to use a fluid, which needs to be heated, as a cooling fluid.

The cooling fluid may then be supplied from a separate process and fed to the cooling means through the cooling circulating line and then passed on to be used for its intended purpose after being heated by the condensation apparatus.

Above, a single circulating line for cooling fluid has been described, the circulating line connecting all the cooling elements in the condensation space. If the condensation space is provided with two or more condensation section an alternative would be to provide several separate circulating lines for cooling fluid, each circulating line providing cooling liquid to cooling means in only one or some of the condensation sections provided in the condensation space. This may for instance be necessary in order to provide the necessary cooling effect in all condensation section if there is provided a relatively large number of condensation sections in the condensation space.

In a preferred embodiment of the invention, the at least one cooling element comprises a pipe or a pipe bundle.

In an embodiment of the present invention the condensation apparatus comprises a heat exchanger arranged after the condensation chamber's outlet such that heat energy contained in remaining gas mixture can be recovered. If the discharge from the outlet of the condensation chamber contains a mixture of the remaining gas mixture and condensate, i.e. first substance in liquid form, the condensation apparatus preferably comprises a combined separator and heat exchanger arranged after the condensation chamber's outlet such that heat energy contained in the condensate and remaining gas mixture can be recovered and the remaining gas mixture and the condensate can be separated.

As can be understood from the description above, the recirculating means may be considered to comprise at least the pump to which the removal line and the supply line are connected such that collected liquid first substance may be recirculated back to the distributing means. Preferably, the recirculating means also comprises a condensate tank for storing the collected liquid first substance before recirculating it back to the distributing means and a line connecting the condensate tank and the pump. In a broader sense, the recirculating means could also be including the removal line or lines from the collecting means and the supply line or lines which supply the liquid first substance to the distributing means. As more liquid first substance may be collected than is needed for recirculation to the distributing means, there should also be provided means, like one or more valves, for draining off at least a portion of the collected first substance. Such a valve or valves could be provided in the condensate tank or in the removal and/or supply lines.

There is also provided a method for separating a first substance from a gas mixture by condensation, the gas mixture being composed of the first substance in gaseous phase and at least one additional substance in gaseous phase. The separation process takes place in a condensation chamber comprising an inlet for gas mixture and an outlet such that a condensation space is created between the inlet and the outlet and where the condensation space comprises at least one condensation section. The method comprises the steps of -introducing the gas mixture, through the inlet, into the condensation chamber at the dew point temperature or slightly above the dew point temperature of the first substance for the given composition and pressure of the gas mixture; -providing the first substance in liquid phase and spraying it into the gas mixture through distributing means arranged in the at least one condensation section; -circulating a cooling liquid through cooling means provided in the at least one condensation section below the distributing means, such that the liquid spray and the gas mixture passes the cooling means; -collecting at least a portion of the liquid first substance in collecting means provided in the condensation chamber above the outlet, and -recirculating at least a portion of the collected liquid first substance to the distributing means such that that declining condensation temperature, as a result of declining partial pressure of the condensing component, is used to enhance condensation in the previous condensation step or steps.

In an embodiment, the method also includes the step of removing the liquid first substance from the collecting means through a removal line and storing the liquid first substance in a condensate tank. In a further embodiment, the method includes the step of supplying the distributing means with liquid first substance which is stored in the condensate tank.

If the condensation space is provided with a plurality of condensation sections, the method also includes the step of collecting a portion of the liquid first substance at the end of each condensation section in collecting means arranged below the cooling means provided in said sections.

Furthermore, the method also includes an embodiment wherein the method also includes the step of recovering heat energy contained in the remaining gas mixture being passed through the outlet in a heat exchanger or in a combined separator and heat exchanger if condensate is present.

There is also provided a use of the condensation apparatus according to any one of the claims ito 10 for the separation of water from a gas mixture composed of substantially carbon dioxide and water vapour.

Furthermore, there is provided a use of the method according to any one of the claims ii to 15 for the separation of water from a gas mixture composed of substantially carbon dioxide and water vapour.

When using the present invention to separate a gas mixture comprising CO2 and H20, the proportion of CO2 in the gas mixture may vary from about 10 mol-% to about 90 mol-% CO2. while at the end the fraction of H20 should be as low as possible since the end products should be dry CO2 gas and "dead water", i.e. water with a very low content of CO2.

Apart from the initial ratio of CO2 and H20 the working pressure and the initial temperature of the gas mixture is important. The pressure is particularly important since the condensation temperature for the water phase is decided by the partial pressure of the water phase, which, at a given mixture ratio, depends directly on the total pressure. The actual pressure for a given process may vary greatly and be crucial for the design of the apparatus. For a thermal power plant with C02-capturing, this pressure can range from atmospheric pressure up to 100 bar.

When the collected condensate is returned to the distributing means and sprayed into the flowing gas mixture, the recirculated condensate has a lower temperature than the flow of gas mixture and a large surface due to the large number of tiny droplets in the spray. This reinforces cooling of the gas mixture and the condensation of the water vapour. The spray also creates movement in the flow of the gas mixture and thereby to smooth out concentration gradients in the gas mixture.

The explanation to the lower temperature of the recirculated condensate is that the condensation temperature decreases along the heating surface because the reduced partial pressure of H20. This effect is enhanced as the partial pressure of 1120 is decreasing which further contribute to the advantage of the system. The diagram below show how the dew point temperature (condensation temperature) decreases with a decreasing concentration of H20 at a given total pressure.

Dew point temperature as a funtion of the ratio C021H20 250 I bar 42 44 46 48 50 52 54 56 58 60 6264 66 68 70 72 74 76 78 80 82 Mol-% C02 As can be seen from the diagram, if the dew point temperature is low compared to the temperature of the cooling medium, the condensation potential may be increased by increasing the total pressure, i.e. by further compressing the gas mixture.

For the heat transport, a characteristic potential may be defined, which is the product of the temperature difference between the surface of the cooling element and the flowing gas mixture and the area of the surface.

For a conventional cooler, the driving potential for the cooling process will then be: A Pi = (tg -tr) *A1, where tg is the gas temperature, tr is the temperature of the surface of the cooling element and Ar is the area of the cooling element.

In the process described herein, a further driving potential is added as follows: A P2 = (tg -tdr) *A, where tg is the gas temperature, tdr is the temperature of the droplets in the spray, and Adr is the total surface area of the droplets in the spray.

The total driving potential for the cooling process is then: A P A P1 + A P2 = (tg -tr) *Ar + (tg -tth) *Afr When the terms on the right side of the equation is considered, the magnitude of the first parenthesis will be slightly larger than the magnitude of the second paranthesis.

The magnitude of the additional driving potential (due to the spray) will to a large extent depend on the additional surface that can be established by the atomizing of the recirculated condensate. With suitable means there are reasons to believe that Adr can be made many times larger than Ar. The additional potential due to the spray can therefore be made at least as large or larger than the original heat exchanging potential. In practice, this means a substantial reduction in the heat exchanging surface (m2), and thereby a reduction in the size of the apparatus as well as cost of manufacturing the apparatus.

As an example of the effect that the recirculation of the condensate can have on the size of the condensation apparatus, an example is given below.

First one condensation section is considered without recirculation of condensate.

The following is assumed: Inlet gas Outlet gas Condensate Pressure 60 bar 60 bar 60 bar CO2 -concentration 60 mol-% 70,6 mol% 0% Temperature 204,5 °C 180,5 °C 174,5 °C (some heat loss included) Amount (mof) 1 mol 0,85 mol 0,15 mol (0,6 mol CO2 + (0,6 mol CO2 + (0,15 mol H20) 0,4 mol H20) 0,25 mol H20) The gas is The gas is saturated with saturated with water vapour, water vapour.

Calculation of energy transferred without recirculation: Heat Capacity of C02: 37 J/mol*K Heat Capacity of water vapour: 34 J/molK Heat Capacity of water: 75 J/mol*K Condensation heat of water: 44000 J/mol Condensation heat for the condensed water: 44000J/mol * 0,15 mol = 6600 J Energy for cooling down: (0,6 * 37 + 04 * 34) * (204,5 180,5) 860 J Total energy transfer: 7460 J Calculation of additional heat added with recirculation of condensed water: Here we assume that the condensed water is sprayed into the gas mixture at the beginning of the condensation section, and that the condensed water is heated to 204,5 °C by the condensing of water vapour. Hence, the water is recirculated only once in this example.

Energy for the condensation taken from recirculated water: 0,15 mol * 30K * 75 J/mol*K = 337,5 J Additional condensed quantity: 337,5 J/44000 J/mol 0,008 mol Recirculating the condensed water once will, in this condensation section, yield an increase of about 5 % in energy transfer and, consequently, the quantity condensed water. Corresponding calculations, where the percentage of CO2 goes from 80 % to %, yields an increase in energy transfer and condensed water of about 10% (based on Hysys' condensation temperatures).

If the water is recirculated more than once, the effect will be greater. In practice, there will probably be at least a 20 % decrease in the size of the condensation apparatus as a consequence of the recirculation of condensed water.

Below, preferred embodiments of the invention will be described with reference to the figures, where Figure 1 is a schematic view of the condensation apparatus according to a first embodiment of the invention.

Figure 2 is a schematic view of a single condensation section of the condensation apparatus according to a second embodiment of the invention.

Figure 3 is a schematic view of the condensation apparatus according to a third embodiment of the invention.

In Figure 1, an embodiment of the condensation apparatus 10 is shown schematically. The condensation apparatus comprises a condensation chamber 12 provided with an inlet 17 and an outlet 18. A fluid line 21 is connected to the inlet 17 and process equipment 20. A process fluid is extracted from the process equipment 20 and fed to the condensation chamber 12 through the fluid line 21.

The process fluid that is fed to the condensation chamber 12 is substantially made up of a gas mixture which contains at least two different substances in gaseous phase where one of the substances is removed from the gas mixture by condensation in the condensation chamber 12. The gas mixture is fed to the condensation chamber in a state such that the substance to be condensed in the condensation chamber is at or slightly above its dew point temperature In the particular embodiments of the invention disclosed below, the gas mixture is made up of substantially carbon dioxide and water vapour.

The gas mixture containing water vapour, is fed to the condensation chamber 15 having a temperature at the dew point temperature or slightly above the dew point temperature of the water for the particular composition and pressure of the gas mixture. The water vapour is condensed in the condensation chamber 12, leaving a S gas mixture of substantially carbon dioxide.

Between the inlet 17 and the outlet 18 of the condensation chamber a condensation space 14 is formed. The condensation space 14 is preferably divided into two or more condensation sections 15, but may also comprise a single condensation section 15. A single condensation section 15 is shown clearly on Figure 2 between the two broken lines 46.

As shown in Figure 1, the condensation apparatus 10 is further provided with distribution means 23. The distribution means 23 distributes a spray of liquid water into the gas mixture flowing through the condensation space 14 in the condensation chamber 12. The distribution means may comprise at least one nozzle 24, but preferably a number of nozzles 24 is used, making up a spray nozzle deck such that substantially the whole horizontal cross section of the condensation space 14 is covered with spray. A supply line 25 is further provided supplying liquid water to the nozzle or nozzles 24. Each of the condensation sections is preferably provided with a nozzle or a number of nozzles 24.

Below the nozzles 24 there is provided cooling means 37. The cooling means comprises at least one cooling element 38 and a circulating line 39 for a cooling fluid. The circulating line 39 extends from a first storage means 40 for cooling fluid to the at least one cooling element 38. From the at least one cooling element 38 the circulating line 39 may extend to a second storage means 41 for cooling fluid. Alternatively the circulating line 39 may extend to another cooling element 38 arranged in the same condensation section 15 or in another condensation section 15. Each of the storage means 40, 41 for cooling fluid, may comprise a container, a tank or any other suitable means for storing the cooling fluid.

Another option would obviously be to use a single storage means for the cooling fluid in stead of the first and second storage means 40, 41.

The cooling fluid may be any suitable liquid or gas which is capable of removing the required amount of heat energy. An option is to use a cooling fluid where the cooling fluid is a liquid which is undergoing a heating process, thereby saving energy that would otherwise be lost. The cooling fluid may also be a liquid at the boiling point, for example, amine in liquid phase at the boiling point. As the amine is passed through the cooling elements 38, the amine will start to boil and boiling amine will be fed to the storage means 41 for used cooling fluid. Obviously, it is also possible to use a gas, like air, as the cooling fluid.

The cooling fluid may be a fluid which circulates in a closed circulating line 39.

The second storage means 41 for cooling fluid and the first storage means 40 for cooling fluid may in that case be interconnected with a fluid line and a heat exchanger such that the cooling fluid can be cooled down before being returned to the first storage means 40. Alternatively, the cooling fluid may also be returned straight to the condensation chamber 12 after having been cooled down in a heat exchanger (not shown on the figures).

As indicated on Figure 1 the circulating line 39 may be arranged on the outside of the condensation chamber 12 between two condensation sections 15. Obviously, it is also possible to arrange the circulating line 39 within the condensation chamber 12 between the condensation sections 15.

In a preferred embodiment of the invention, the cooling element 38 comprises a pipe or a pipe bundle.

Below the cooling element 38, there is provided collecting means 26 comprising a collecting plate 27, as shown in Figure 1, or one or preferably a number of receptacles 28, as shown in Figure 2. The collecting plate 27 shown in Figure 1 comprises a plate that covers the whole horizontal cross section of the condensation chamber 12 such that all the water in liquid form is collected by the collecting plate 27. To allow the remaining gas mixture to pass through the collecting plate 27, the collecting plate is provided with a through going hole and a pipe socket 31 surrounding the hole and preventing collected liquid water from flowing through the hole. Above the pipe socket 31 there is provided a cover 32 arranged such that there is a gap between the upper edge of the pipe socket 31 and the cover 32.

Droplets from the spray and/or condensed water vapour is stopped by the cover and can not pass through the hole, while the remaining gas mixture is allowed to pass underneath the cover 32 and through the hole to the next condensation section 15 or to the outlet 18 of the condensation chamber 12.

Liquid water which has been collected by the collecting plate 27, can be removed by a removal line 29 which is connected to a condensate tank 33. The condensate tank 33 preferably also acts as a feeding tank for the pump 35 which recirculates the condensate to the distributing means 23 through the fluid line 25 which is connected to the pump 35. Each condensation section 15 is preferably provided with a collecting plate 27 and removal lines 29 connects the collecting plates 27 to the condensate tank 33.

The condensation apparatus further comprises a fluid line 43 which is connected to the outlet 18 of the condensation chamber 12. Remaining gas mixture is passed through the fluid line 43 and fed to a heat exchanger 44 or optionally a combined separator and heat exchanger if some liquid water is allowed to pass through the collecting means 26. That may happen, for example if the collecting means 26 comprises receptacles 28, as shown in Figure 2, that do not cover the entire cross section of the condensation chamber 12. In the heat exchanger 44, heat may be recovered from the gas mixture that would otherwise have been wasted.

Figure 2 discloses a single condensation section 15 of the condensation chamber's condensation space. As already mentioned above, the condensation space may comprise a single condensation section 15 or preferably a number of condensation sections.

The nozzle deck comprising a plurality of nozzles 24 are shown. The nozzles 24 are connected to a line 25 through which liquid first substance is fed to the nozzles 24.

Consequently, a a spray of the first substance is injected into the gas mixture, indicated in figure 2 by arrows 47. Below the nozzles 24, cooling means 37 is arranged. In the embodiment shown, the cooling means comprises a cooling element 38 in the form of a pipe bundle through which a cooling liquid is circulated.

Below the cooling means 37 the collecting means 26 is arranged. In the embodiment shown on figure 2, the collecting means comprises at least one receptacle 28, preferably a number of receptacles 28, and a removal line 29 to which all the receptacles 28 are connected such that collected condensate can be removed. The removal line 29 is connected to a condensate tank 33 which also acts as a feeding tank for the pump 35 which recirculates the condensate back to the nozzles 24 through the line 25.

Figure 3 discloses an embodiment of the invention where the condensation chamber is arranged such that the flow of gas mixture is substantially horizontal through the condensation sections. In the embodiment shown on figure 3, the condensation chamber 12 is provided with four condensation sections 15, but the number of condensation sections can be higher or lower. The gas mixture is fed from the process equipment 20 and into the condensation chamber 12 through an inlet 17.

The gas mixture leaves the condensation chamber 12 through an outlet 18.

Each of the four condensation sections 12 comprises distributing means 23 which injects a spray of the first substance into the flow of the gas mixture. The distributing means 23 is arranged in the upper part of the condensation section which means that the direction of flow of gas mixture and the direction of flow of the spray from the distributing means 23 are substantially perpendicular.

Below the distributing means 23, cooling means 38 is arranged. The distributing means 23 is connected to a first storage 40 means for cooling fluid and a second storage means 41 for cooling fluid through a cooling circulating line 39. First and second storage means 40, 41 for cooling fluid may be provided for each condensation section or a single storage means for the cooling liquid may be used.

As mentioned earlier, the cooling fluid may be a fluid that is used in a separate process and needs to be heated. The cooling fluid may then be fed to the cooling elements 38 and returned to process equipment (not shown on the figures) directly through the cooling fluid circulating line 39. In this embodiment, storage means 40, 41 for the cooling liquid may be provided if necessary.

The collecting means of the embodiment shown in figure 3, is simply formed by the bottom of the condensation chamber 12. On the figure, each condensation section is provided with an outlet to which a removal line 29 is connected. The removal lines 29 are connected to respective condensate tanks 33 which also serve as feeding tanks for the pumps. The pumps will pump the condensate (first substance in liquid form) back to the distributing means through the supply lines 25. On figure three it is shown that the condensate from one condensation section 15 is supplied to the distributing means 23 in the neighbouring condensation section. Condensate from one of the end-condensation sections is supplied to the distributing means 23 in the opposite end-condensation section. As shown on figure 3, the condensate being pumped from one end-condensation section to the opposite end-condensation section, may be passed through a heat exchanger 50.

Claims

CLAIMS1. Condensation apparatus for the removal of a first substance from a gas mixture which is composed of the first substance in gaseous phase and at least one additional substance in gaseous phase, the condensation apparatus comprising a condensation chamber with an inlet for the gas mixture and an outlet such that a condensation space is created between the inlet and the outlet, the condensation space comprising one or more condensation sections, c h a r a c t e r i z e d i n that each condensation section comprises -distributing means for the distribution of the first substance, in the form of a spray, into the gas mixture, and -cooling means arranged below the distributing means wherein a cooling medium is circulated, and that the condensation space is provided with collecting means for the collecting of at least a portion of the first substance in liquid form and recirculation means recirculating at least a portion of the collected first substance in liquid form to the distributing means such that declining condensation temperature, as a result of declining partial pressure of the condensing component, is used to enhance condensation in the previous condensation step or steps.
2. Condensation apparatus according to claim 1, c h a r a c t e r i z e d i n that the distributing means comprises at least one nozzle and a supply line for the supply of the first substance in liquid form to the at least one nozzle.
3. Condensation apparatus according to claim I or claim 2, c h a r a c t e r i z e d i n that the collecting means comprises a collecting plate covering substantially the entire cross section of the condensation chamber and a removal line, wherein the collecting plate comprises throughflow means such that the gas mixture can pass through the collecting plate while liquid is collected by the collecting plate.
4. Condensation apparatus according to one of the claims 1-3, c h a r a c t e r i z e d i n that the collecting means comprises at least one receptacle and a removal line for the removal of liquid first substance from the at least one receptacle.
5. Condensation apparatus according to one of the claims 1-4, c h a r a c t e r i z e d i n that each condensation section is provided with collecting means arranged below the cooling means of said condensation section.
6. Condensation apparatus according to one of the claims 1-5, c h a r a c t e r i z e d j n that the removal line is connected to a condensate tank and that the supply line is connected to a pump which in turn is connected to the condensate tank such that the liquid first substance collected by the collecting means may be circulated back to the distributing means and sprayed into the gas mixture.
7. Condensation apparatus according to one of the claims 1-6, c h a r a c t e r i z e d i n that the cooling means comprises at least one cooling element and a cooling fluid circulating line such that a cooling fluid may be circulated through the at least one cooling element.
8. Condensation apparatus according to claim 7, c h a r a c t e r i z e d i n that the cooling element comprises a pipe or a pipe bundle.
9. Condensation apparatus according to one of the claims 1-8, c h a r a c t e r i z e d i n that the condensation apparatus comprises a heat exchanger arranged after the condensation chamber's outlet such that heat energy contained in the condensate and remaining gas mixture can be recovered.
10. Condensation apparatus according to one of the claims 1-8, c h a r a c t e r i z e d i n that the condensation apparatus comprises a combined separator and heat exchanger arranged after the condensation chamber's outlet such that heat energy contained in the condensate and remaining gas mixture can be recovered and the remaining gas mixture and the condensate can be separated.
11. Method for separating a first substance from a gas mixture by condensation, the gas mixture being composed of the first substance in gaseous phase and at least one additional substance in gaseous phase, the separation process taking place in a condensation chamber comprising an inlet for gas mixture and an outlet such that a condensation space is created between the inlet and the outlet, the condensation space comprising at least one condensation section, characterized in tbatthemethodcomprisesthestePSof -introducing the gas mixture, through the inlet, into the condensation chamber at the dew point temperature or slightly above the dew point temperature of the first substance; -providing the first substance in liquid phase and spraying it into the gas mixture through distributing means arranged in the at least one condensation section; -circulating a cooling liquid through cooling means provided in the at least one condensation section below the distributing means, such that the liquid spray and the gas mixture passes the cooling means; -collecting at least a portion of the liquid first substance in collecting means which is provided in the condensation chamber, and -recirculating at least a portion of the collected liquid first substance to the distributing means such that that declining condensation temperature, as a result of declining partial pressure of the condensing component, is used to enhance condensation in the previous condensation step or steps.
12. Method according to claim II, c h a r a c t e r i z e d i n that the method also includes the step of removing the liquid first substance from the collecting means through a removal line and storing the liquid first substance in a condensate tank.
13. Method according to claim 12, c h a r a c t e r i z e d i n that the method also includes the step of supplying the distributing means with liquid first substance which is stored in the condensate tank.
14. Method according to one of the claims 11-13, c h a r a c t e r i z e d i n that the method also includes the step of collecting a portion of the liquid first substance at the end of each condensation section in collecting means arranged below the cooling means provided in said sections.
15. Method according to one of the claims 11-14, c h a r a c t e r i z e d i n that the method also includes the step of recovering heat energy contained in the remaining gas mixture being passed through the outlet in a heat exchanger or in a combined separator and heat exchanger if condensate is present.
16. Use of the condensation apparatus according to any one of the claims I to 10 for the separation of water from a gas mixture composed of substantially carbon dioxide and water vapour.
17. Use of the method according to any one of the claims 11 to 15 for the separation of water from a gas mixture composed of substantially carbon dioxide and water vapour.