TW201336573A - A gas processing unit comprising a device for removing nitrogen oxides - Google Patents

Abstract

A gas purification system for cleaning a carbon dioxide rich flue gas stream comprises: a flue gas condenser (36) operative for removing at least a portion of a water content of the flue gas; a gas drier (70) arranged downstream of the flue gas condenser (36) for removing at least a portion of a remaining water content of the flue gas; a gas drier regeneration system (84) arranged for generating a regeneration gas for desorbing water and nitrogen oxides from the gas drier (70); and a wet scrubber (114) for a spent regeneration gas from the gas drier (70) to contact an absorption liquid for removing at least a portion of nitrogen oxides from the spent regeneration gas to form a cleaned regeneration gas.

Description

Gas processing unit containing a device for removing nitrogen oxides

The present invention relates to a method of purifying a carbon dioxide-rich flue gas produced by burning a fuel in a boiler in the presence of an oxygen-containing gas.

The invention further relates to a gas purification system for purifying a carbon dioxide-rich flue gas stream produced by burning a fuel in a boiler in the presence of an oxygen-containing gas.

Heat generating combustion gases in a combustion plant (such as power plants), the fuel (such as coal, oil, peat, waste, etc.), the process gas other than also contain other components comprising carbon dioxide CO _2. As environmental demands have increased, various methods of removing carbon dioxide from process gases have been developed. One such method is known as the oxy-fuel process. In the oxy-fuel process, a fuel, such as one of the above-described fuels, is combusted in a boiler in the presence of a nitrogen-poor gas. The oxygen supplied by the oxygen source is supplied to the boiler for oxygen oxidation of the fuel. In an oxyfuel combustion process, a carbon dioxide-rich flue gas is produced. The CO ₂ in the carbon dioxide-rich flue gas can be captured and disposed of in order to reduce carbon dioxide emissions to the atmosphere.

CO ₂ capture often involves compressing and cooling the flue gas to separate CO _{2 in} liquid or solid form from non-condensing flue gas components such as N ₂ and O ₂ . Prior to CO ₂ capture, it is generally desirable to purify the flue gas rich in carbon dioxide.

US 2010/0206165 discloses a method, wherein the gas stream between the purification step and the purification of carbon dioxide recovered in the CO-rich stream ₂ containing purge. The purification step involves the use of an adsorbent to remove water from the gas stream.

It is an object of the present invention to provide a method of removing water from a gas stream in a more efficient manner than prior art methods.

This object is achieved by a method of purifying carbon dioxide-rich flue gas produced by burning fuel in the presence of an oxygen-containing gas in a boiler, the method comprising: removing flue gas from a flue gas condenser At least a portion of the moisture; removing at least a portion of the residual moisture in the flue gas and at least a portion of the nitrogen oxides in the flue gas using a gas dryer disposed downstream of the flue gas condenser; by heating the regeneration gas stream to a suitable The gas dryer regenerates the temperature, and passes the heated regeneration gas through the gas dryer to desorb water and nitrogen oxides from the gas dryer to produce waste regeneration gas to regenerate the gas dryer; The spent regeneration gas of the gas dryer is delivered to the wet scrubber, and the spent regeneration gas is contacted with the absorption liquid to remove at least a portion of the nitrogen oxides of the spent regeneration gas to form a purified regeneration gas.

The advantage of this method is the use of very efficient methods to limit the release of nitrogen oxides to the environment at low investment and operating costs. The operating conditions of the gas dryer allow the gas dryer to act as a nitrogen oxide collector, while the wet scrubber acts as a purification device that ultimately removes nitrogen oxides from the carbon dioxide rich flue gas.

According to an embodiment, the method further comprises delivering a purified regeneration gas stream from the wet scrubber to the flue gas condenser for cooling therein. The advantage of this embodiment is to limit the release of undesired gases, such as carbon dioxide and nitrogen oxides, to the atmosphere, avoiding large-scale processing methods because waste regeneration gases are used in other equipment (ie, smoke) that have been used in the same process. Processed in the gas condenser).

According to one embodiment, the method further comprises supplying an oxidant to the absorption fluid of the wet scrubber. The advantage of this embodiment is the nitrogen oxides in the wet scrubber (one of the details) The capture of nitrogen oxides NO) is further enhanced.

According to an embodiment, the method further comprises obtaining a regeneration gas stream by withdrawing a portion of the carbon dioxide-rich flue gas downstream of the flue gas condenser. An advantage of this embodiment is the use of process gases already within the process. This reduces operating costs without increasing the amount of carbon dioxide that is ultimately delivered for isolation.

According to an embodiment, the method further comprises obtaining a regeneration gas stream by withdrawing a portion of the carbon dioxide rich flue gas upstream of the gas dryer. An advantage of this embodiment is the use of a gas that has not been dried as a regeneration gas. This reduces operating costs.

According to an embodiment, the method further comprises supplying a pH control substance to the absorption liquid of the wet scrubber. An advantage of this embodiment is, for example, that the acidic compound formed by the capture of nitrogen oxides by the wet scrubber absorbing liquid can be neutralized, thereby increasing the nitrogen oxide capture efficiency.

According to one embodiment, the wet scrubber is spaced from the flue gas condenser. An advantage of this embodiment is that the wet scrubber and the flue gas condenser can each be optimized according to their respective tasks.

According to one embodiment, the method further comprises transporting waste regeneration gas from the gas dryer through the wet scrubber during washing, the washing period comprising a portion of the regeneration period of the gas dryer regeneration, and based on nitrogen oxides The release of the gas dryer controls the duration and timing of the wash period. An advantage of this embodiment is that consumables such as energy and oxidant can be saved because the wet scrubber operates only when needed.

Another object of the present invention is to provide a gas purification system that effectively purifies a carbon dioxide-rich flue gas stream.

This objective is achieved by a gas purification system for purifying a carbon dioxide-rich flue gas stream produced by burning a fuel in the presence of an oxygen-containing gas in a boiler, the gas purification system comprising: a flue gas condenser for effectively removing smoke At least a portion of the moisture in the gas; a gas dryer disposed in the flow based on the flow of the carbon dioxide-rich flue gas Downstream of the gas condenser for removing at least a portion of the remaining moisture in the flue gas and at least a portion of the nitrogen oxides in the flue gas; a gas dryer regeneration system configured to generate a regeneration gas from the Desorbing water and nitrogen oxides of the gas dryer; and a wet scrubber for contacting the spent regeneration gas from the gas dryer with the absorption liquid to remove at least a portion of the nitrogen oxides of the spent regeneration gas, A purified regeneration gas is formed.

The advantage of this system is the use of very efficient systems to limit the release of nitrogen oxides into the environment.

According to an embodiment, the system further comprises a conduit for the purified regeneration gas to flow from the wet scrubber to the flue gas condenser for cooling therein. An advantage of this embodiment is that the nitrogen oxides and carbon dioxide emitted to the environment are extremely low.

According to an embodiment, the system further comprises a supply conduit downstream of the flue gas condenser for flow of regeneration gas into the gas dryer regeneration system based on the flow of the carbon dioxide rich flue gas. An advantage of this embodiment is the use of the process gas already within the process as a regeneration gas. This reduces operating costs and the volume of gas that needs to be processed.

According to one embodiment, the gas dryer contains a solid adsorbent. An advantage of this embodiment is that the solid adsorbent is generally effective to remove water vapor such that the flue gas exiting the gas dryer has a low concentration of water vapor and is suitable for further disposal of the flue gas.

According to an embodiment, the system further comprises an oxidant supply tube configured to supply oxidant to the wick of the wet scrubber. An advantage of this embodiment is to enhance the ability of the wet scrubber to remove nitrogen oxides and, in particular, one of the nitrogen oxides.

According to one embodiment, at least one compressor is disposed downstream of the flue gas condenser and upstream of the gas dryer for compressing the carbon dioxide rich flue gas based on the flow direction of the carbon dioxide rich flue gas. Based on the flow direction of the carbon dioxide-rich flue gas, a supply conduit is disposed upstream of the compressor for regeneration gas to flow into the gas dryer regeneration system. An advantage of this embodiment is that regeneration can be achieved using the collected regeneration gas prior to compression, thereby reducing operating costs. Another advantage is that compressing the carbon dioxide-rich flue gas promotes the oxidation of nitric oxide NO to form nitrogen dioxide NO ₂ . Thus, a larger portion of the nitrogen oxides trapped in the gas dryer and delivered to the wet scrubber after regeneration has been in an oxidized state, reducing the need to supply oxidant to the wet scrubber.

According to one embodiment, the at least one pH control substance supply tube is configured to supply a pH control substance to the absorption liquid of the wet scrubber.

The above and other features are exemplified by the following figures and embodiments. Other objects and features of the present invention will be apparent from the embodiments and appended claims.

1‧‧‧Boiler system

2‧‧‧Boiler

2a‧‧‧burning area

4‧‧‧ Turbine Power Generation System

6‧‧‧Gas purification system

8‧‧‧Particle removal device

10‧‧‧Sulphur dioxide removal system/wet scrubber

10a‧‧‧ Wet scrubber interior

12‧‧‧ fuel storage

14‧‧‧Supply tube

16‧‧‧Oxygen source

18‧‧‧Supply pipeline

20‧‧‧ Pipes

22‧‧‧ steam pipe

24‧‧‧ Pipes

26‧‧‧ Pipes

27‧‧‧ Pipes

28‧‧‧Circulating pump

30‧‧‧Slurry circulation tube

32‧‧‧ Pipes

33‧‧‧ gas distribution point

34‧‧‧ Pipes

36‧‧‧ Flue Gas Condenser

37‧‧‧Disposal tube

38‧‧‧ Pipes

40‧‧‧Gas Compression and Purification Unit (GPU)

41‧‧‧Compressor

42‧‧‧First compression phase

44‧‧‧Second compression phase

46‧‧‧ Third compression stage

48‧‧‧Low compression unit

50‧‧‧Common drive shaft

52‧‧‧Motor

54‧‧‧Intermediate cooling unit

56‧‧‧ gas cooler

58‧‧‧ gas-liquid separator

60‧‧‧ Mercury adsorber

60a‧‧‧Filling

62‧‧‧ Pipes

64‧‧‧ Pipes

66‧‧‧ Pipes

68‧‧‧ Pipes

70‧‧‧ gas dryer

72‧‧‧Filling

74‧‧‧ Pipes

76‧‧‧CO ₂ liquefaction unit

78‧‧‧High pressure compression unit

80‧‧‧CO2 isolator

82‧‧‧ Pipes

84‧‧‧Gas Dryer Regeneration System

86‧‧‧Supply pipeline

88‧‧‧heater

90‧‧‧heating circuit

91‧‧‧ gas delivery device

92‧‧‧ Pipes

94‧‧‧Temperature Sensor

96‧‧‧ valve

98‧‧‧Regeneration valve

100‧‧‧Regeneration valve

102‧‧‧ Pipes

104‧‧‧Gas Dryer Isolation Valve

106‧‧‧Gas Dryer Isolation Valve

108‧‧‧ Pipes

110‧‧‧ gas dryer

111‧‧‧Optional pipe

112‧‧‧Configuration

114‧‧‧ Wet scrubber

116‧‧‧ pump

118‧‧‧Circulation tube

120‧‧‧The lower end of the wet scrubber

122‧‧‧ Wet scrubber

124‧‧‧The upper end of the wet scrubber

126‧‧‧Wet scrubber gas-liquid contact filling material

128‧‧‧ Pipes

129‧‧‧Optional pipe

130‧‧‧pH control substance supply tube

131‧‧‧ gas mixing device

132‧‧‧pH meter

133‧‧‧Oxiant supply tube

134‧‧‧Control valve

135‧‧‧Static mixing board

136‧‧‧Oxidant supply tube

138‧‧‧ Redox Potentiometer

140‧‧‧Control valve

142‧‧‧ pump

144‧‧‧Circulation tube

146‧‧‧ lower end of the condenser casing

148‧‧‧Condenser housing

148a‧‧‧ inside the condenser casing

150‧‧‧Upper end of condenser housing

152‧‧‧Condenser gas-liquid contact filling material

154‧‧‧Liquid cooler

156‧‧‧ Pipes

158‧‧‧Disposal tube

160‧‧‧Waste treatment plant

162‧‧‧ tube

164‧‧‧ tube

166‧‧‧Waste treatment plant

168‧‧‧Optional bypass piping

170‧‧‧ Valve / First Step

171‧‧‧Optional valve

172‧‧‧ second step

174‧‧‧ third step

176‧‧‧ fourth step

178‧‧‧ fifth step

The invention is described in more detail below with reference to the accompanying drawings in which:

Figure 1 is a schematic side view of a boiler system.

Figure 2 is a schematic side view of a gas compression and purification unit.

Figure 3 is a schematic side view of a system for purifying spent regeneration gas.

Figure 4 is a graph illustrating the concentration of nitrogen oxides in the spent regeneration gas during regeneration of the gas dryer.

Figure 5 is a schematic illustration of a method of purifying a carbon dioxide rich flue gas.

Figure 1 is a schematic side view of a boiler system 1. The boiler system 1 includes a boiler 2 (an oxygen fuel boiler in this embodiment), a steam turbine power generation system 4, and a gas purification system 6 as main components. The gas purification system 6 includes a particulate removal device 8, which may be, for example, a fabric filter or an electrostatic precipitator; and a sulfur dioxide removal system 10, which may be a wet scrubber.

A fuel, such as coal, oil or peat, is housed in the fuel reservoir 12 and may be supplied to the boiler 2 via a fluid communication supply pipe 14. Oxygen source 16 is effective in supplying oxygen in a manner known to those skilled in the art. The oxygen source 16 can be an air separation device that effectively separates oxygen from the air, an oxygen separation membrane, a storage tank, or any other source that provides oxygen to the boiler system 1. Supply conduit 18 allows the generated oxygen gas (typically comprising 90 to 99.9% by volume of oxygen gas O ₂₎ may be in fluid communication with the flow to the boiler 2. The conduit 20 allows the recycled flue gas containing carbon dioxide to flow to the boiler 2 in fluid communication. As shown in Figure 1, the supply conduit 18 is connected to the conduit 20 upstream of the boiler 2 such that oxygen and recycled flue gas containing carbon dioxide can be mixed upstream of the boiler 2 to form a gas mixture which typically contains from about 20% to about 50% by volume. Oxygen, the rest is mainly carbon dioxide and water vapor. Since almost no air enters the boiler 2, almost no nitrogen gas is supplied to the boiler 2. In actual operation, less than 3% by volume of the gas supplied to the boiler 2 is air, which enters the boiler system 1 in the form of leakage air mainly via, for example, the boiler 2 and the gas purification system 6.

The boiler 2 effectively combusts the fuel supplied via the supply pipe 14 in the presence of oxygen mixed with the carbon dioxide-containing recycled flue gas supplied via the fluid communication conduit 20. The combustion takes place in a portion of the boiler referred to herein as the combustion zone 2a. The steam pipe 22 allows steam generated in the boiler 2 due to combustion to flow into the steam turbine power generation system 4, which effectively produces power in the form of electric power.

The conduit 24 allows the carbon dioxide-rich flue gas stream produced in the boiler 2 to be in fluid communication with the dust removal device 8. As used herein, "carbon dioxide-rich flue gas" means that the flue gas contains at least 40% by volume of carbon dioxide, CO ₂ . Typically more than 50% by volume of the flue gas leaving the boiler 2 will be carbon dioxide. Typically, the flue gas exiting boiler 2 will contain 50-80% by volume of carbon dioxide. The remainder of the "carbon dioxide-rich flue gas" is about 15-40% by volume of water vapor (H ₂ O), 2-7 vol% of oxygen (O ₂ ) (since a slight excess of oxygen in boiler 2 is usually Preferably, and a total of about 0-10% by volume of other gases (mainly including nitrogen (N ₂ ) and argon (Ar), since some air leakage is rarely avoided altogether).

The carbon dioxide-rich flue gas produced in the boiler 2 may generally comprise pollutants such as HCl, sulfur oxides SO _X and heavy metals (including mercury Hg) in the form of dust particles, which should be disposed of prior to disposal of carbon dioxide. The flue gas rich in carbon dioxide is at least partially removed. In addition, a certain amount of nitrogen oxides (ie, nitric oxide NO and/or nitrogen dioxide NO ₂ ) may also be present in the boiler due to leakage of air into the boiler 2 and/or nitrogen contained in the fuel supplied to the boiler 2. Produced in 2.

The dust removal device 8 removes most of the dust particles from the carbon dioxide rich flue gas. The conduit 26 allows the carbon dioxide rich flue gas to flow from the dedusting device 8 into the fluidly connected wet scrubber 10 of the gas purification system 6. The wet scrubber 10 includes a circulation pump 28 that is effective to circulate the absorbing liquid in the fluid communication slurry circulation tube 30. The absorbing liquid contains, for example, limestone. The slurry circulation tube 30 in the wet scrubber 10 provides good contact between the absorbing liquid and the flue gas flowing into the wet scrubber 10 via the fluid communication conduit 26 and flowing substantially vertically upward into the interior 10a of the wet scrubber 10, To effectively remove sulfur dioxide SO ₂ and other acid gases from flue gas rich in carbon dioxide.

At least a portion of the purified carbon dioxide-rich flue gas exits the wet scrubber 10 via a fluid communication conduit 32 to a fluidly connected gas split point 33 where the at least partially purified carbon dioxide-rich flue gas is split into two streams, That is, the first stream that is recycled back to the boiler 2 via the fluid communication conduit 20 and the second stream that is delivered to the flue gas condenser 36 via the fluid communication conduit 34. The first stream recycled back to the boiler 2 via line 20 typically accounts for 50-75 vol% of the total purified carbon dioxide-rich flue gas exiting the wet scrubber 10. The second stream typically accounts for 25-50% by volume of the total purified carbon dioxide-rich flue gas exiting the wet scrubber 10 and is therefore delivered via line 34 to the flue gas condenser 36. According to an alternative embodiment, the first stream may be recycled back to the boiler 2 via the fluid communication conduit 27 without passing through the wet scrubber 10.

In the flue gas condenser 36, the flue gas is cooled to below its water dew point and the heat released by the resulting condensation is recovered as low temperature heat. An example of a flue gas condenser is described in EP 2 335 804 A1, with reference to Figures 3 and 4 of this document.

Returning to Figure 1 of the present invention, the water content of the flue gas can be reduced, for example, from about 20-50% by volume when fed to the flue gas condenser 36 to about 2-7% by volume when leaving the flue gas condenser 36. . Depending on pH and the flue gas condenser, the temperature may be 36, the flue gas condensation may also cause the flue gas sulfur oxide SO _X reduction. Sulfur oxides in the flue gas are trapped in the condensate formed and thereby separated from the flue gas. In addition, the wash liquor or slurry (eg, lime slurry) entrained in the flue gas from the aforementioned sulfur dioxide removal process (eg, from the limestone-based wet scrubber 10) is also removed during condensation. Therefore, the fouling and/or clogging problems of the downstream gas dryer and/or gas heater surface are reduced. Flue gas condenser 36 has a circulation pump that is effective to circulate coolant through a fluid communication loop located in flue gas condenser 36 in a manner described in more detail below. The coolant circulating in the flue gas condenser 36 cools the partially purified carbon dioxide rich flue gas to a temperature below its saturation temperature relative to the water vapor. Thus, at least a portion of the water vapor from the partially purified carbon dioxide-rich flue gas flowing from the wet scrubber 10 condenses. The condensed water leaves the flue gas condenser 36 via a fluidly connected disposal tube 37. A portion of the condensed water exiting the flue gas condenser 36 via line 37 can flow into the wet scrubber 10 as make-up water. Another portion of the condensed water can flow into the water treatment unit where the condensed water is treated and subsequently reused in the process (eg, as boiler water) or disposed of. The purified carbon dioxide rich flue gas exits the flue gas condenser 36 via a fluid communication conduit 38 and flows into a gas compression and purification unit (GPU) 40.

FIG. 2 illustrates an embodiment of GPU 40 in more detail. It should be understood that the description of FIG. 2 is schematic and that the GPU may include other devices for gas purification, and the like.

GPU 40 includes at least one compressor having at least one and typically two to ten compression stages for compressing the purified carbon dioxide rich flue gas. Each compression stage can be configured as a separate unit. As an alternative and as illustrated in Figure 2, several compression stages can be operated by a common driver. The GPU 40 of FIG. 2 includes a compressor 41 having a first compression stage 42, a second compression stage 44, and a third compression stage 46. The first to third compression stages 42, 44, 46 together form a low pressure compression unit 48 of the GPU 40. The compression stages 42, 44, 46 are coupled to a common drive shaft 50 that is driven by a motor 52 of the compressor 41.

The low pressure compression unit 48 can be included downstream of some or all of the compression stages 42, 44, 46 Intermediate cooling unit 54. One such optional intermediate cooling unit 54 is illustrated downstream of the first compression stage 42 of FIG. The intermediate cooling unit 54 includes a gas cooler 56 and a gas-liquid separator 58. The gas cooler 56 cools the compressed carbon dioxide rich flue gas to a temperature below the dew point temperature of the compressed carbon dioxide rich flue gas to the water, causing the water vapor in the flue gas to condense. The gas-liquid separator 58 separates water droplets from the remaining flue gas, which are generated by the condensation caused by the gas cooler 56 cooling the gas.

GPU 40 may include a mercury adsorber 60 disposed downstream of one of compression stages 42, 44, 46. In the embodiment of FIG. 2, the mercury adsorber 60 is disposed downstream of the third compression stage 46, that is, downstream of the low pressure compression unit 48. It should be understood that the mercury adsorber 60 can also be configured to treat flue gas between the first compression stage 42 and the second compression stage 44 or between the second compression stage 44 and the third compression stage 46.

The partially purified carbon dioxide rich flue gas enters GPU 40 from flue gas condenser 36 via fluid communication conduit 38 and is introduced into first compression stage 42. The conduit 62 allows the compressed gas from the first compression stage 42 to flow into the second compression stage 44 via the intermediate cooling unit 54 as appropriate. The conduit 64 allows the compressed gas from the second compression stage 44 to flow into the third compression stage 46 via an intermediate cooling unit (not shown in Figure 2) as appropriate. The conduit 66 allows compressed gas from the third compression stage 46 to flow into the mercury adsorber 60. The mercury adsorber 60 is equipped with a filler 60a containing a mercury adsorbent having an affinity for mercury. The adsorbent can be, for example, activated carbon impregnated with sulfur or other materials known per se to have an affinity for mercury. The conduits 68, 108 allow compressed gas having a pressure of about 25-35 bar absolute to flow from the mercury adsorber 60 into the gas dryer 70.

A gas dryer 70 is used to remove at least a portion of the remaining water vapor from the compressed gas. A portion of the compressed gas is also adsorbed nitrogen oxides NO _x in the gas drier 70 at least. The gas dryer 70 is equipped with a packing 72 comprising a solid adsorbent for adsorbing water vapor and optionally adsorbing other gas components such as nitrogen oxides. The solid adsorbent may, for example, comprise activated carbon, silicone, activated alumina, zeolite molecular sieves such as sodium aluminosilicate, and carbon molecular sieves. A detailed description of various useful solid adsorbents is provided in Chapter 2 of the manual "Adsorption aus der Gasphase", Werner Kast, Wiley-VCH (1988), ISBN-10: 3527267190. Zeolite molecular sieves are an example of such suitable solid adsorbents. As described in the above-referenced Werner Kast, the internal surface area " o " of the solid adsorbent may preferably be at least 50 m ² /g, and more preferably at least 250 m ² /g. Zeolite molecular sieves have open structures in which small molecules such as water vapor molecules and nitrogen oxide molecules can diffuse and be adsorbed. In one embodiment, the solid adsorbent can be a zeolite molecular sieve comprising, for example, sodium aluminosilicate. The zeolite molecular sieve can be, for example, a 3A or 4A zeolite molecular sieve. Thus, as the compressed carbon dioxide-rich flue gas passes through the packing 72, at least a portion of the water vapor and a portion of the nitrogen oxides in the gas are adsorbed onto the solid adsorbent of the packing 72. The portion of the nitrogen oxides in the compressed gas that is removed in the gas dryer 70 depends on the type and amount of solid adsorbent. For example, 30-99.9% of the nitrogen oxides in the compressed gas can be removed in the gas dryer 70.

In one example, the compressed carbon dioxide-rich flue gas exiting gas dryer 70 via fluid communication conduit 74 has an absolute pressure of between about 25 and 35 bar. The gas also has a reduced content of water vapor and NO _x. As illustrated in Figure 2, the processing unit is further adapted to the gas 78 in a CO ₂ liquefaction unit 76 and the high-pressure compressor, in fluid communication via conduit 82 and then flows into the carbon dioxide separator 80.

The gas dryer 70 is equipped with a gas dryer regeneration system 84 for the water vapor adsorption capacity of the intermittent regeneration gas dryer 70. Supply conduit 86 is configured to supply regeneration gas to regeneration system 84. The regeneration system 84 uses a portion of the carbon dioxide rich flue gas stream as the regeneration gas. Based on the flow direction of the flue gas, a portion of the carbon dioxide-rich flue gas stream is preferably withdrawn as a regeneration gas downstream of the flue gas condenser 36 rather than upstream of the gas dryer 70. In the embodiment of FIG. 2, a carbon dioxide rich flue gas stream is then withdrawn from the fluid communication conduit 38 downstream of the flue gas condenser 36 for use as a regeneration gas. Alternatively, airflow may be drawn from another location (e.g., any of conduits 62, 64, and 66) for use as a regeneration gas.

The regeneration system 84 includes a heater 88 for heating the regeneration gas. Heating circuit 90 is coupled to heater 88 for circulating a heating medium, such as steam, in heater 88. Heated The regeneration gas exits the heater 88 via a fluid communication conduit 92. A gas delivery device (such as a blower, compressor or fan) 91 may be disposed in conduit 92 to draw regeneration gas from conduit 38 and further through heater 88. Temperature sensor 94 is disposed in conduit 92 to measure the temperature of the heated regeneration gas. Valve 96 is disposed in heating circuit 90 for controlling the flow of heating medium to heater 88. Temperature sensor 94 controls valve 96 to supply an appropriate amount of heating medium. To regenerate the material of the packing 72 of the gas dryer 70, the heater 88 typically heats the regeneration gas to a temperature of between about 130 ° C and 315 ° C. In one embodiment of the 3A or 4A zeolite molecular sieve used as the desiccant material for the filler 72, the regeneration temperature may preferably range from about 200 °C to 290 °C.

Regenerative valves 98, 100 are disposed on conduit 92 and conduit 102, respectively. During the regeneration sequence, valves 98, 100 are opened to allow regeneration gas to pass through gas dryer 70.

Gas dryer isolation valves 104, 106 are disposed on conduits 68, 74, respectively. During the regeneration sequence, valves 104, 106 are closed to isolate gas dryer 70 from the flow of compressed gas from low pressure compression unit 48. The regeneration valves 98, 100 are opened and the heated regeneration gas is supplied from the regeneration system 84 to the gas dryer 70 via a conduit 108 that is in fluid communication to the conduit 92. Heating the regeneration gas and the filler material 72 so that water vapor and nitrogen oxides NO _x desorption. Comprising the de-adsorption of NO _x and water vapor spent regeneration gas leaving the gas drier 70 via line 102.

It should be understood that the carbon dioxide rich gas may not pass through the gas dryer 70 when the valves 104, 106 are closed. According to one embodiment, GPU 40 may be equipped with another gas dryer 110 that is parallel to gas dryer 70 so that gas dryer 70 is being regenerated while the other gas dryer 110 is in operation. Optional conduit 111, illustrated with dashed lines in FIG. 2, is provided through a further optional gas dryer 110 during regeneration of gas dryer 70 by providing a flue gas rich in carbon dioxide. To keep this clear, the valves required to isolate the other gas dryer 110 from the gas dryer 70 during normal operation of the gas dryer 70 and during regeneration of another gas dryer 110 are not shown in FIG. . According to another embodiment, the carbon dioxide rich flue gas can be released around the dryer 70 during regeneration of the packing 72 of the gas dryer 70. To the atmosphere.

3 illustrates a configuration 112 for purifying spent regeneration gas exiting gas dryer 70 via fluid communication conduit 102 after regeneration of filler 72. The spent regeneration gas flows into the fluidly connected regeneration gas purification wet scrubber 114 via conduit 102. The wet scrubber 114 is equipped with a pump 116 such that the wick is circulated from the lower end 120 of the wet scrubber 122 via the recycle line 118 to the upper end 124 of the wet scrubber 122. The absorbing liquid is distributed at the upper end 124 to the wet scrubber gas-liquid contacting fill material 126 of the wet scrubber 122. Examples of the gas-liquid contact 126 comprising a filler material available from Sulzer Chemtech AG, Winterthur, CH of Mellapak ^TM, and commercially available from Raschig GmbH Ludwigshafen, DE Pall ^TM of the ring.

The spent regeneration gas enters the wet scrubber 122 at the lower end 120 via the fluid communication conduit 102 and flows upwardly through the wet scrubber 122 in a substantially vertical direction and is in contact with the absorbing fluid in the wet scrubber gas-liquid contact fill material 126. . The purified regeneration gas exits the wet scrubber 124 via a conduit 128 that is in fluid communication with the upper end 124 to the wet scrubber 122. The wet scrubber 114 is typically operated intermittently while achieving regeneration of the gas dryer 70.

According to an alternative embodiment, the spent regeneration gas may flow into the upper end 124 of the wet scrubber 122 and substantially vertically downward through the column 122 and exit the column 122 at the lower end 120.

According to another alternative embodiment, the absorbing liquid supplied at the upper end 124 of the column 122 can be atomized by the nozzle to further enhance the contact between the absorbing liquid and the spent regeneration gas.

Returning to Fig. 3, the pH control substance supply pipe 130 is fluidly connected to the circulation pipe 118 for supplying the pH control substance to the circulating absorption liquid. The pH meter 132 is configured to measure the pH of the sorbent circulating in the circulation tube 118. The pH meter 132 controls the valve 134 to regulate the amount of pH control substance supplied via the supply tube 130. Examples of the pH controlling substance which can be supplied via the supply pipe 130 include basic substances such as NaOH, KOH, Na ₂ CO ₃ and NaHCO ₃ ; and acidic substances such as H ₂ SO ₄ , HCl and HNO ₃ . The alkaline material is typically used to neutralize the reaction product formed by the capture of nitrogen oxides, as will be described in more detail below, but in some cases, the carbon dioxide-rich flue gas itself may contain the supply of acidic material. The trace amount of the alkaline substance is such that the absorption liquid circulating in the circulation pipe 118 maintains the desired pH. The pH of the absorbing liquid circulating in the circulation pipe 118 is usually controlled within the pH range of pH 5-8.

Additionally, oxidant supply line 136 is in fluid communication with circulation tube 118 for supplying oxidant to the circulating absorbing liquid. The redox potentiometer 138 can optionally be configured to measure the redox potential of the absorbing liquid circulating in the circulation tube 118. The redox potentiometer 138 controls the valve 140 to regulate the amount of oxidant supplied via the oxidant supply tube 136 to maintain the desired redox potential in the absorbing liquid. According to an alternative embodiment, the supply of oxidant is fixed and a fixed volume of oxidant solution is supplied per hour. According to another alternative embodiment, the supply of oxidant solution may be based on the amount of spent regeneration gas passing through the wet scrubber 114.

Examples of the oxidizing agent that can be supplied via the oxidizing agent supply pipe 136 include potassium permanganate KMnO ₄ , hydrogen peroxide H ₂ O _{2 ,} and ozone O ₃ . The oxidant will usually be supplied in the form of an aqueous solution or a gas. In the case where the supply of oxidant gas in the form of, for example, when the supply of the oxidant in the form of ozone O _3, optional gas mixing device 131 may be disposed upstream of the duct 102 114 wet scrubber. The gaseous oxidant may be supplied to the gas mixing device 131 via the oxidant supply pipe 133. The gas mixing device 131 can be equipped with a static mixing plate 135 to mix the supplied gaseous oxidant with the spent regeneration gas before it enters the wet scrubber 114. Therefore, the ozone supplied via the tube 133 is first mixed with the gas in the gas mixing device 131, and then flows into the absorption liquid of the wet scrubber 114.

The purified spent regeneration gas exiting the wet scrubber 122 via line 128 is delivered to the flue gas condenser 36 via conduit 34 that is in fluid communication to the conduit 128. The flue gas condenser 36 is equipped with a pump 142 such that the coolant circulates from the lower end 146 of the condenser housing 148 through the circulation tube 144 to the upper end 150 of the outer casing 148. The coolant is distributed at the upper end 150 over the condenser gas-liquid contacting fill material 152 disposed within the interior 148a of the outer casing 148. The gas-liquid contact fill material 152 can have a similar type to the fill material 126 described above. A liquid cooler 154 is disposed in the circulation pipe 144 for cooling the coolant. Partially purified dioxide-rich from boiler 2 via line 34 The carbon flue gas and the purified regeneration gas delivered by the wet scrubber 114 via line 128 are combined into a common stream that enters the outer casing 148 via the fluid communication conduit 156 at the lower end 146 and flows upwardly in a substantially vertical direction. The coolant-cooled outer casing 148 and the filling material 152 supplied through the circulation pipe 144. As a result of this cooling, at least a portion of the partially purified carbon dioxide-rich flue gas and the purified regeneration gas condense and form a condensate. The condensate exits the flue gas condenser 36 via the treatment tube 37 for further processing as described above. The waste from the wet scrubber 114 via another disposal tube 158 can optionally be combined with the condensate of the disposal tube 37 and sent away for further processing therewith. For example, the combined liquid can be delivered to a wastewater treatment plant 160. A pH control material, such as NaOH, may optionally be supplied to the circulating coolant of tube 144 via fluid communication tube 162 to maintain a constant pH of the circulating coolant.

According to an alternative embodiment, waste liquid from the wet scrubber 114 via another treatment tube 158 may flow through the tube 164 to a respective wastewater treatment plant 166. Thus, the effluent from wet scrubber 114 and flue gas condenser 36 can be treated separately according to their particular composition. The purified carbon dioxide rich flue gas exits the flue gas condenser 36 via the fluid communication conduit 38 and is delivered to the GPU 40 along with the purified and cooled regeneration gas. As described above with reference to Figure 2, a portion of the gas flowing through conduit 38 can be delivered via line 86 to heater 88 of gas dryer regeneration system 84 for heating and as regeneration gas for regeneration of fill material 72 of gas dryer 70. .

Optional bypass conduit 168 can be in fluid communication with conduits 102 and 34. When the concentration of nitrogen oxides in the regeneration gas falls below a predetermined value, it is no longer necessary to purify the spent regeneration gas in the wet scrubber 114. In this case, valve 170 can be opened to cause at least a portion of the spent regeneration gas to flow directly from conduit 102 via fluid communication conduits 168 and 34 to flue gas condenser 36 such that at least a portion of the spent regeneration gas bypasses wet scrubber 114. . Optionally, another optional valve 171 disposed in the conduit 102 immediately upstream of the wet scrubber 114 can be closed while the valve 170 is opened such that most, if not all, of the gas bypasses the wet scrubber 114 in this case. . For example, valve 170 can be opened based on actual measurements of nitrogen oxide concentration in conduit 102, or valve 170 can be opened at a fixed time after regeneration sequence is initiated, as found by, for example, empirical experiments, fixed time has been found. The nitrogen oxide concentration is sufficiently low.

Fig. 4 is a graph showing the relationship between the concentration of nitrogen oxides in the spent regeneration gas and the elapsed time after the regeneration of the gas dryer 70 is started. The x-axis depicts time (hours) and the y-axis depicts the concentration of nitrogen oxides (mg NO _x /Nm ³ spent regeneration gas) over time. As can be seen in Figure 4, the concentration of nitrogen oxides in the spent regeneration gas has a rather narrow peak. Thus, the nitrogen oxides collected on the solid adsorbent of the packing 72 of the gas dryer 70 are released over a relatively limited period of time. According to one embodiment, the wet scrubber 114 described above with reference to FIG. 3 operates in conjunction with the solid adsorbent of the gas dryer 70 to release nitrogen oxides. According to this embodiment, when the concentration of nitrogen oxides in the spent regeneration gas is high, the waste regeneration gas flows through the wet scrubber 114, and when the concentration of nitrogen oxides in the waste regeneration gas is low, the waste regeneration gas is directly delivered. Pass through condenser 36. According to one example, gas dryer 70 begins regeneration at time T0 illustrated in FIG. At time T1, the concentration of nitrogen oxides in the spent regeneration gas begins to surge. Thus, closing valve 170 at time T1 means that spent regeneration gas flows through wet scrubber 114 where nitrogen oxides are removed. At time T2, the nitrogen oxide concentration is again lowered to a low concentration. Thus, valve 170 is opened at time T2 such that most, if not all, of the spent regeneration gas bypasses wet scrubber 114 and directly enters condenser 36. The regeneration of the gas dryer 70 is ended at time T3. In this embodiment, regeneration of the gas dryer 70 occurs at a regeneration period starting at T0 and finally T3. The spent regeneration gas flows through the wet scrubber 114 during a wash period beginning at T1 and finally T2 and forming part of the regeneration period. The duration of the wash period (T1 to T2) is typically 20-80% of the duration of the complete regeneration period (T0 to T3). Thus, with respect to this method, the wet scrubber 114 is operated to remove nitrogen oxides as necessary, and at other times, the spent regeneration gas is at least partially delivered directly to the condenser 36. This method reduces the consumption of power, oxidant, etc. of the wet scrubber 114. The timing of turning the scrubber 114 on and off (i.e., timings T1 and T2) can be determined, for example, by measuring the concentration of nitrogen oxides in the spent regeneration gas continuously or in conjunction with a particular test, such as GPU 40 startup. The timing of the release of nitrogen oxides from gas dryer 70 can also be predicted based on scientific calculations or experience with other facilities. Thus, the timing of the washout period can be based on the measurement and/or prediction of the release of nitrogen oxides from the gas dryer 70.

Figure 5 illustrates an embodiment of a method of purifying a carbon dioxide rich flue gas.

In a first step 170, at least a portion of the at least partially purified carbon dioxide-rich flue gas is condensed in the flue gas condenser 36.

In a second step 172, more water is removed from the at least partially purified carbon dioxide-rich flue gas from the flue gas condenser 36 by passing the gas through the gas dryer 70. In addition to water, the packing 72 of the gas dryer 70 can also remove other components (including nitrogen oxides) from the gases passing therethrough. "Nitrogen oxides" include nitric oxide NO and nitrogen dioxide NO ₂ .

In a third step 174, the gas portion is heated and used as a regeneration gas for the filler of the regeneration gas dryer 70. As illustrated in Figures 2 and 3, the gas portion can be collected, for example, downstream of the flue gas condenser 36. The regeneration of the gas dryer 70 releases water vapor and nitrogen oxides (NO and NO ₂ ) and possibly traces of other substances into the regeneration gas.

In a fourth step 176, it contains water vapor and nitrogen oxides (NO and NO ₂₎ of the spent regeneration gas from the gas drier 70 flows to the wet scrubber 114. cleaned. In the wet scrubber 114, at least a portion of the nitrogen oxides are removed from the spent regeneration gas. If the oxidizer 136 via the supply pipe, the oxidizing agent can help nitric oxide NO to nitrogen dioxide NO _2. For example, if the oxidant hydrogen peroxide H ₂ O _{2 is} supplied to the wet scrubber 114, the following oxidation reaction may occur: NO + H ₂ O ₂ → NO ₂ + H ₂ O [Equation 1.1]

Nitric Oxide NO Oxidation to Form Nitrogen Dioxide NO ₂ may also spontaneously occur in the packing 72 of the gas dryer 70 and the wet scrubber 114 in the presence of a small amount of oxygen in the carbon dioxide rich flue gas and regeneration gas. Therefore, the oxidant may not be necessary to achieve oxidation of nitric oxide. Further, compressing the carbon dioxide-rich flue gas by the compressor 41 illustrated in FIG. 2 promotes oxidation of nitric oxide NO to form nitrogen dioxide NO ₂ . The pressure that promotes oxidation of nitric oxide reduces the consumption of oxidant.

Nitrogen dioxide NO ₂ can then be converted to nitric acid HNO ₃ in the wet scrubber 114 : 3 NO ₂ + H ₂ O → NO + 2 HNO ₃ [Equation 1.2]

Finally, the formed nitric acid can be neutralized by the alkaline substance supplied through the pH control substance supply pipe 130. For example, if sodium hydroxide NaOH is supplied to the wet scrubber 114, the following neutralization reaction may occur: HNO ₃ + NaOH → NaNO ₃ + H ₂ O [Equation 1.3]

The formed sodium nitrate NaNO _{3 is} dissolved in the circulating absorbent of the wet scrubber 114 and disposed of via another disposal tube 158, such as in a water treatment plant 166 for further processing. Neutralizing nitric acid according to Equation 1.3 reduces the equilibrium vapor pressure of nitrogen oxides and pushes Equation 1.2 to the right, making the absorption of nitrogen dioxide NO ₂ more efficient. The total amount of NO ₂ entering the wet scrubber nitrogen dioxide, typically about 60 to 99.9% of 114 and 114, one enters the wet scrubber is typically 20-95% of the total of the nitrogen monoxide NO will be removed from the spent regeneration gas.

In a fifth step 178, the purified regeneration gas flows from the wet scrubber 114 to the flue gas condenser 36. In the flue gas condenser 36, at least a portion of the water vapor in the purified regeneration gas is condensed.

Thus, the use of the method of the present invention allows for efficient regeneration of the gas dryer 70 (in terms of energy and gas consumables), avoids or at least reduces the release of nitrogen oxides into the atmosphere, and avoids or at least reduces nitrogen oxides in portions. Accumulated in the purified carbon dioxide-rich flue gas.

It should be understood that numerous variations of the above-described embodiments are within the scope of the appended claims.

As described above, a portion of the carbon dioxide-rich flue gas stream is withdrawn downstream of the flue gas condenser 36 rather than upstream of the gas dryer 70 for use as a regeneration gas. It should be understood that the regeneration gas may also be obtained at other locations. According to an alternative embodiment, the regeneration gas may be withdrawn from any of the conduits 62, 64, 108, and 74. Another type of regeneration gas can also be used, such as a ring Air. An advantage of withdrawing regeneration gas from line 38 is that the regeneration gas has a relatively low concentration of water vapor and a low level of oxygen. In addition, the compression work has not been added to the regeneration gas. The regeneration of the gas dryer 70 is typically carried out at atmospheric pressure, especially if the spent regeneration gas will return upstream of the flue gas condenser 36. Therefore, the pressure of the regeneration gas above the environment may not be applicable.

A solid adsorbent (e.g., zeolite molecular sieve) has been described above as the filler 72 of the gas dryer 70. According to an alternative embodiment, the liquid drying agent is used to contact the flue gas and to capture the water vapor in the gas dryer 70. Examples of the liquid desiccant which can be used in this embodiment include diethylene glycol, triethylene glycol and tetraethylene glycol as described in section 20 of GPSA Engineering Data Book, 2004, 12th edition, ISBN: B00006KFVO.

According to one embodiment, the gas condenser 36 can perform the following two functions: removing at least a portion of the moisture in the flue gas and removing at least a portion of the nitrogen oxides from the spent regeneration gas as a wet scrubber. In this case, the spent regeneration gas may flow directly to the gas condenser 36 via the optional conduit 129. The gas condenser 36 may optionally be supplied with an oxidant such as potassium permanganate KMnO ₄ , hydrogen peroxide H ₂ O ₂ and/or ozone O ₃ to oxidize the nitrogen oxides trapped therein.

In summary, a gas purification system for purifying a carbon dioxide-rich flue gas stream comprises: a flue gas condenser 36 for effectively removing at least a portion of the moisture in the flue gas; and a gas dryer 70 disposed in the flue gas condenser Downstream 36 for removing at least a portion of residual moisture in the flue gas; gas dryer regeneration system 84 configured to generate regeneration gas to desorb water and nitrogen oxides from gas dryer 70; and wet The scrubber 114 is configured to contact the spent regeneration gas from the gas dryer 70 with the absorption liquid to remove at least a portion of the nitrogen oxides in the spent regeneration gas to form a purified regeneration gas.

While the invention has been described with respect to the preferred embodiments the embodiments of the invention In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments of the inventions Moreover, the use of the terms first, second, etc. does not denote any <RTI ID=0.0> </ RTI> order or importance, but the terms first, second, etc. are used to distinguish one element from another.

34‧‧‧ Pipes

36‧‧‧ Flue Gas Condenser

37‧‧‧Disposal tube

38‧‧‧ Pipes

40‧‧‧Gas Compression and Purification Unit (GPU)

70‧‧‧ gas dryer

72‧‧‧Filling

86‧‧‧Supply pipeline

88‧‧‧heater

91‧‧‧ gas delivery device

92‧‧‧ Pipes

102‧‧‧ Pipes

112‧‧‧Configuration

114‧‧‧ Wet scrubber

116‧‧‧ pump

118‧‧‧Circulation tube

120‧‧‧The lower end of the wet scrubber

122‧‧‧ Wet scrubber

124‧‧‧The upper end of the wet scrubber

126‧‧‧Wet scrubber gas-liquid contact filling material

128‧‧‧ Pipes

129‧‧‧Optional pipe

130‧‧‧pH control substance supply tube

131‧‧‧ gas mixing device

132‧‧‧pH meter

133‧‧‧Oxiant supply tube

134‧‧‧Control valve

135‧‧‧Static mixing board

136‧‧‧Oxidant supply tube

138‧‧‧ Redox Potentiometer

140‧‧‧Control valve

142‧‧‧ pump

144‧‧‧Circulation tube

146‧‧‧ lower end of the condenser casing

148‧‧‧Condenser housing

148a‧‧‧ inside the condenser casing

150‧‧‧Upper end of condenser housing

152‧‧‧Condenser gas-liquid contact filling material

154‧‧‧Liquid cooler

156‧‧‧ Pipes

158‧‧‧Disposal tube

160‧‧‧Waste treatment plant

162‧‧‧ tube

164‧‧‧ tube

166‧‧‧Waste treatment plant

168‧‧‧Optional bypass piping

170‧‧‧ valve

171‧‧‧Optional valve

Claims (16)

A method of purifying a carbon dioxide-rich flue gas produced by burning a fuel in a boiler (2) in the presence of an oxygen-containing gas, the method comprising: removing in a flue gas condenser (36) At least a portion of the moisture in the flue gas; removing at least a portion of the residual moisture in the flue gas and at least a portion of the flue gas using a gas dryer (70) disposed downstream of the flue gas condenser (36) a portion of the nitrogen oxide; regenerating the gas dryer (70) by heating the regeneration gas stream to a temperature suitable for regeneration of the gas dryer (70), and passing the heated regeneration gas through the gas dryer ( 70) to desorb water and nitrogen oxides from the gas dryer (70); and to transport waste regeneration gas from the gas dryer (70) to the wet scrubber (114) for contact with the absorption liquid And removing at least a portion of the nitrogen oxides from the spent regeneration gas to form a purified regeneration gas. The method of claim 1, further comprising obtaining the regeneration gas stream by withdrawing a portion of the carbon dioxide-rich flue gas downstream of the flue gas condenser (36). The method of claim 1, further comprising obtaining the regeneration gas stream by withdrawing a portion of the carbon dioxide-rich flue gas upstream of the gas dryer (70). The method of claim 1, further comprising delivering the purified regeneration gas stream from the wet scrubber (114) to the flue gas condenser (36) for cooling therein. The method of claim 1, further comprising supplying an oxidant to the absorbing liquid of the wet scrubber (114). The method of claim 1, further comprising supplying a pH control substance to the absorption liquid of the wet scrubber (114). The method of claim 1, wherein the temperature suitable for regeneration of the gas dryer is 130 ° C It is in the range of 315 ° C, more preferably in the range of 200 ° C to 290 ° C. The method of claim 1, wherein the wet scrubber (114) is spaced from the flue gas condenser (36). The method of claim 1, further comprising passing waste regeneration gas from the gas dryer (70) through the wet scrubber (114) during the washing, the washing period comprising regenerating the regeneration of the gas dryer (70) a portion of the period; and controlling the duration and timing of the wash period based on the release of nitrogen oxides from the gas dryer (70). A gas purification system for purifying a carbon dioxide-rich flue gas stream produced by burning a fuel in a boiler (2) in the presence of an oxygen-containing gas, the gas purification system comprising: a flue gas condenser ( 36) which effectively removes at least a portion of the moisture in the flue gas; a gas dryer (70) disposed downstream of the flue gas condenser (36) for removing at least a portion of the flue gas Residual moisture and at least a portion of the nitrogen oxides in the flue gas; a gas dryer regeneration system (84) configured to generate a regeneration gas to desorb water and nitrogen oxides from the gas dryer (70) And a wet scrubber (114) for contacting the spent regeneration gas from the gas dryer (70) with the absorption liquid to remove at least a portion of the nitrogen oxides from the spent regeneration gas to form a purified regeneration gas. The gas purification system of claim 10, further comprising a supply conduit (86) disposed downstream of the flue gas condenser (36) for the regeneration gas to flow into the gas dryer regeneration system (84). The gas purification system of claim 10, further comprising a supply conduit (86) disposed upstream of the gas dryer (70) for the regeneration gas to flow into the gas dryer regeneration system (84). A gas purification system according to claim 10, wherein at least one compressor (41) for compressing the carbon dioxide-rich flue gas is disposed downstream of the flue gas condenser (36) and upstream of the gas dryer (70) And a supply conduit (86) is disposed upstream of the compressor (41) for the regeneration gas to flow into the gas dryer regeneration system (84). The gas purification system of claim 10, further comprising a conduit (128) for the purified regeneration gas to flow from the wet scrubber (114) to the flue gas condenser (36) for cooling therein. The gas purification system of claim 10, further comprising an oxidant supply tube (136; 133) configured to supply oxidant to the absorbing liquid of the wet scrubber (114). A gas purification system according to claim 10, wherein the gas dryer (70) contains a solid adsorbent.