TW201304851A - A method of cleaning a carbon dioxide rich flue gas - Google Patents

Abstract

A method and a gas purification system for cleaning a carbon dioxide rich flue gas generated in a boiler (2) combusting a fuel in the presence of a gas containing oxygen gas, the method comprising: removing at least a portion of the water content of the flue gas in a flue gas condenser (36); compressing the carbon dioxide rich flue gas in a compressor (41) arranged downstream of the flue gas condenser (36), as seen in the flow direction of the flue gas; removing at least a portion of the remaining water content of the flue gas using molecular sieves in a gas drier (70) arranged downstream of the compressor (41); regenerating the molecular sieves by withdrawing a portion of the carbon dioxide rich flue gas downstream of the flue gas condenser (36), but upstream of the compressor (41), heating the withdrawn flue gas to a temperature suitable for regeneration of the molecular sieves, passing the heated flue gas through the gas drier (70) to desorb water and NOx from the molecular sieves; and returning the carbon dioxide rich flue gas containing the desorbed water and NOx to the boiler (2).

Description

Method for purifying carbon dioxide rich flue gas

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

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

The fuel (such as coal, oil, peat, waste, etc.) in a combustion device (such as power plants) when the combustion, high temperature process gas, the process gas contains in particular carbon dioxide CO ₂ component. With the increasing demand for the environment, various methods of self-contained gas removal of carbon dioxide have been developed. One such method is the so-called oxidizing fuel method. In the oxidizing fuel process, a fuel, such as one of the above fuels, is combusted in the presence of a lean nitrogen gas. Oxygen supplied by an oxygen source is supplied to the boiler, wherein the oxygen oxidizes the fuel. In an oxidative fuel combustion process, carbon dioxide rich flue gas is produced which can be treated to reduce carbon dioxide emissions to the atmosphere.

CO ₂ capture typically involves compressing and cooling the flue gas to separate the CO ₂ from a non-condensable flue gas component, such as N ₂ and O ₂ , in liquid or solid form.

It is often necessary to purify the carbon dioxide rich flue gas prior to CO ₂ capture. Gas purging operation generally may include removing dust, sulfides, metals, nitrogen oxides (NO _x) and the like.

Current systems and methods to reduce the emissions of NO _x, such as selective catalytic reduction (SCR), dependent on the use of chemicals (e.g., ammonia) to the NO _x is reduced to N _2.

In the combustion of oxidizing fuel, oxygen is used instead of air. Generating object-based CO ₂ rich flue gas, the gas processing unit which can be transported and stored before (GPU) in compression and purification. To provide a low nitrogen content of the gas combustion process flue gas produced with a relatively low content of NO _x. However, since the _two forms of NO NO _x to molecular sieves can adsorb a GPU, therefore the molecular sieve during the regeneration, exhaust gas may be present in high concentrations of NO _2.

One object of the present invention to provide a system in the purification method of flue gas of a boiler combustion of the fuel-rich carbon dioxide produced in the presence of an oxygen-containing gas, relative to prior art methods, this method results in atmospheric discharge of NO _x to be cut back.

According to the aspect set forth herein, a method of purifying a carbon dioxide-rich flue gas produced by burning a fuel in the presence of an oxygen-containing gas in a boiler, the method comprising: removing at least a portion of the flue gas from the flue gas condenser Water content; compressing the carbon dioxide-rich flue gas in a compressor disposed downstream of the flue gas condenser, as seen in the direction of flow of the flue gas; using the molecular sieve in the gas dryer disposed downstream of the compressor to remove at least a portion of the residual water in the flue gas Content: by extracting a portion of the carbon dioxide-rich flue gas downstream of the flue gas condenser and upstream of the compressor, heating the extracted flue gas to a temperature suitable for molecular sieve regeneration, and passing the heated flue gas through a gas dryer to desorb the molecular sieve water and NO _x, so that the regenerated molecular sieve; and adsorbed water-containing solutions of NO _x and CO rich flue gas is returned to the boiler.

According to an embodiment of the herein-containing solution of the adsorbed water and carbon dioxide rich flue gas NO _x to return to the boiler, the NO _x decomposition in the high temperature combustion zone of the boiler, without consuming any chemicals and does not produce any additional waste stream . This will help to eliminate the step of removing the additional requirements of NO _x, such as selective catalytic reduction, thereby reducing the overall cost of the boiler system and operating costs.

One advantage of this method is that no chemical reactants or catalysts are required and no additional waste products are formed. Moreover, the process can be carried out in an existing gas purification system with only a few structural modifications to purify the carbon dioxide-rich flue gas produced by burning the fuel in the presence of an oxygen-containing gas in the boiler. No additional containers or reactors are required.

According to an embodiment, the extracted flue gas is heated to a temperature between 130 ° C and 315 ° C.

According to an embodiment, the extracted flue gas is heated to a temperature between 200 ° C and 290 ° C.

A portion of the carbon dioxide rich flue gas downstream of the flue gas condenser should be used to regenerate the gas dryer because the flue gas has been at least partially purified. The dust removal and sulfur removal steps, typically upstream of the flue gas condenser, significantly reduce the clogging and fouling problems of soot, fly ash, and other particulate matter (such as metals) entering the molecular sieve, thereby extending the life of the molecular sieve. In addition to reducing the water content of the flue gas, another advantage of the flue gas condenser is that the wash liquor or slurry (eg, lime slurry) entrained in the flue gas from the previous sulfur dioxide removal step is removed during condensation, thus further Reduce fouling and/or clogging problems in gas dryers.

According to an embodiment, the method further comprises subjecting the flue gas stream to dust removal upstream of the flue gas condenser, as seen in the direction of flow of the flue gas.

According to an embodiment, the method further comprises subjecting the flue gas stream to sulfur dioxide removal upstream of the flue gas condenser, as seen in the direction of flow of the flue gas.

According to other aspects set forth herein, 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 is provided, the gas purification system comprising: a method for removing flue gas a flue gas condenser having at least a portion of water content; a compressor disposed downstream of the flue gas condenser for compressing the carbon dioxide rich flue gas, as seen in a flow direction of the carbon dioxide rich flue gas; and a downstream configuration of the compressor for shifting in addition to the molecular sieve containing the water content of the flue gas at least part of the residual gas dryer, such as the direction of flow of the carbon dioxide rich flue see; for desorption and regeneration gas dryer system of water and a molecular sieve of NO _x; the gas dryer The regeneration system includes: a gas conduit for extracting a portion of the carbon dioxide-rich flue gas stream downstream of the flue gas condenser and upstream of the compressor and guiding the portion of the carbon dioxide-rich flue gas stream through the gas dryer and returning to the boiler, and a The extracted carbon dioxide-rich flue gas is heated to a temperature suitable for molecular sieve regeneration before it enters the gas dryer Flue gas heater.

According to an embodiment, the extracted flue gas is heated to a temperature between 130 ° C and 315 ° C.

According to an embodiment, the extracted flue gas is heated to a temperature between 200 ° C and 290 ° C.

According to an embodiment, the system further includes a dust removal filter disposed upstream of the flue gas condenser, as seen in the direction of flow of the flue gas.

According to an embodiment, the system further includes a scrubber upstream of the flue gas condenser for removing sulfur dioxide, as seen by the direction of flow of the flue gas.

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

Referring now to the drawings, the drawings are exemplary embodiments

Figure 1 is a schematic illustration of a boiler system 1, as seen from its side. The boiler system 1 comprises a boiler 2 as a main component, in this embodiment an oxidizing fuel boiler, a steam turbine power generation system, shown as 4, and a gas purification system 6. The gas purification system 6 includes a particulate removal device, which may be, for example, a fiber filter or electrostatic precipitator 8, and a sulfur dioxide removal system, which may be a wet scrubber 10.

A fuel such as coal, oil or peat is contained in the fuel storage device 12 and can be supplied to the boiler 2 via the supply pipe 14. The fuel can be transferred to the boiler, for example, by a recirculating portion of the flue gas stream from the flue gas condenser 36, which will be further described below. Oxygen source 16 operates in a known manner to provide oxygen. The oxygen source 16 can be an air separation plant for separating oxygen from air, an oxygen separation membrane, a storage tank, or any other source that provides oxygen to the boiler system 1. Duct system 18 for supplying the generated oxygen (typically comprising 90 to 99.9% by volume of oxygen, O ₂₎ 2 fed to the boiler. The conduit 20 is used to deliver recycled flue gas (carbon dioxide) to the boiler 2. As shown in Figure 1, the supply conduit 18 connects the conduit 20 upstream of the boiler 2 such that oxygen and recycled flue gas (carbon dioxide containing) can be mixed with each other to form a gas generally containing about 20-50% by volume of oxygen upstream of the boiler 2. The mixture, the rest is mainly carbon dioxide and water vapor. Since almost no air enters the boiler 2, nitrogen gas is hardly supplied to the boiler 2. In actual operation, less than 3% by volume of the gas volume supplied to the boiler 2 is air, which enters the boiler system 1 mainly via leaks via, for example, the boiler 2 and the gas purification system 6. The boiler 2 is for combusting a fuel mixed with recycled flue gas (carbon dioxide) supplied via a pipe 20 in the presence of oxygen, which is supplied via a supply pipe 14. Combustion will occur in the portion of the boiler referred to herein as the combustion zone. The steam pipe 22 is used to deliver steam (generated in the boiler 2 due to combustion) to the steam turbine power generation system 4 (for power generation in the form of electrical energy).

The duct 24 is for conveying the carbon dioxide-rich flue gas generated in the boiler 2 to the dust removing device 8. "Carbon dioxide-rich flue gas" means flue gas leaving the boiler 2 via a conduit 24 will contain at least 40% by volume of carbon dioxide, CO _2. More than 50% by volume of the flue gas leaving the boiler 2 will typically be carbon dioxide. The flue gas leaving the boiler 2 will typically contain 50-80% by volume of carbon dioxide. Since the oxygen in the boiler 2 is usually slightly excessive, the balance of "carbon dioxide rich flue gas" will be about 15-40% by volume of water vapor (H ₂ O), 2-7 vol% of oxygen (O ₂ ), and due to leakage. Gas is almost completely unavoidable, for a total of about 0-10% by volume of other gases (mainly including nitrogen (N ₂ ) and argon (Ar)).

The carbon dioxide-rich flue gas produced in the boiler 2 may generally include pollutants in the form of, for example, dust particles, hydrochloric acid (HCl), sulfide (SO _X ), and heavy metals (including mercury (Hg)). Before, at least a portion of the carbon dioxide-rich flue gas should be removed.

The dust removal device 8 removes most of the dust particles from the carbon dioxide rich flue gas. The conduit 26 is used to deliver carbon dioxide rich flue gas from the fiber filter 8 to the wet scrubber 10 of the gas purification system 6. The wet scrubber 10 includes a circulation pump 28 for circulating an absorbing liquid (including, for example, limestone) in the slurry circulation pipe 30 from the bottom of the wet scrubber 10 to the upper portion of the wet scrubber 10 Configure one of the set of nozzles. The slurry nozzle is used to finely distribute the absorbing liquid in the wet scrubber 10 so that the absorbing liquid and the flue gas flowing through the conduit 26 to the wet scrubber 10 and flowing substantially vertically upward in the wet scrubber 10 are good. Contact to remove sulfur dioxide (SO ₂ ) and other acid gases from the effective carbon dioxide-rich flue gas.

At least a portion of the purified carbon dioxide-rich flue gas exits the wet scrubber 10 via line 32 to deliver flue gas to the gas split point 33, and at least a portion of the purified carbon dioxide-rich flue gas is split into two streams, a first stream, via a conduit The 20 is recycled back to the boiler 2, and the second stream is sent via line 34 to the flue gas condenser 36. The first stream that is recycled back to the boiler 2 via line 20 typically accounts for 50-75 vol% of the total flow of the partially purified carbon dioxide-rich flue gas exiting the wet scrubber 10. Thus, the second stream is delivered via line 34 to the flue gas condenser 36, which typically accounts for 25-50% by volume of the total flow of the partially purified carbon dioxide rich flue gas exiting the wet scrubber 10.

In the flue gas condenser 36, the flue gas is cooled below its water dew point, and the heat released by the resulting condensation is recovered as low temperature heat. For example, the water content of the flue gas can be reduced from about 40% by volume of the flue gas fed to the flue gas condenser to about 5% by volume of the flue gas exiting the flue gas condenser. Depending on pH and temperature of the flue gas condenser, flue gas condensation may also result in reduced flue gas sulfide (SO _X) of. Sulfide is trapped in the formed condensate and separated from the flue gas. Moreover, the wash or slurry (e.g., lime slurry) entrained in the flue gas from the previous sulfur dioxide removal step is removed during condensation, thereby reducing fouling and/or clogging of the gas dryer and/or gas heater surface. problem. The flue gas condenser 36 has a circulation pump for circulating the coolant through a circulation tube in the flue gas condenser 36 in a manner to be described in detail below. The coolant circulated 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, and thus to the partial purification of the transport from the wet scrubber 10 At least a portion of the water vapor content of the carbon dioxide rich flue gas condenses. The condensed water leaves the flue gas condenser 36 via the treatment tube 37. Part of the condensed water exiting the flue gas condenser 36 via line 37 can be delivered to the wet scrubber 10 with compensating water. Another portion of the condensed water can be sent to the water treatment unit where the condensed water is reused in the process (e.g., as boiler water) or disposed of prior to disposal. The purified carbon dioxide rich flue gas leaves the flue gas condenser 36 via conduit 38 and is delivered to GPU 40.

In a gas compression and purification unit (GPU) 40, a portion of the purified carbon dioxide-rich flue gas from the flue gas condenser 36 is further purified and compressed. Thus, the compressed carbon dioxide exits GPU 40 via conduit 80 and is transported for processing, sometimes referred to as "CO ₂ sequestration." GPU 40 specifically includes at least one compressor 41 for compressing carbon dioxide-rich flue gas from FGC 36 and at least one gas dryer 70. The gas dryer 70 is for removing at least a portion of the residual water vapor content of the compressed gas. Similarly, the compressed gas is at least partially absorbed in the NO _x content of the gas drier.

FIG. 2 illustrates one embodiment of a gas dryer 70. The gas dryer 70 is equipped with Placed downstream of the compressor 41 as seen in the direction of flow of the flue gas. The compressed carbon dioxide rich flue gas is supplied from the compressor 41 via a mercury adsorber (not shown in FIG. 2) and via a fluid connection line 68 to the gas dryer 70 as appropriate. The gas dryer 70 has a packing 112 comprising a molecular sieve having an affinity for water vapor. The molecular sieve may, for example, comprise an aluminosilicate mineral, clay, porous glass, microporous charcoal, zeolite, activated carbon or a synthetic compound having a loose structure through which small molecules (such as water vapor) can diffuse and adsorb, or Its combination. In one embodiment, the molecular sieve comprises hydrated aluminosilicate. The molecular sieve can be, for example, a 3A or 4A molecular sieve.

Thus, as the compressed carbon dioxide rich flue gas passes through the packing 112, at least a portion of the water vapor content of the gas will adsorb to the molecular sieve of the packing 112.

In one example, the compressed carbon dioxide rich flue gas exiting gas dryer 70 via line 72 has a temperature of 30 ° C and an absolute pressure just below 30 bar absolute. The water vapor content of the gas is also reduced. This gas is suitable for further processing in the CO ₂ liquefaction unit and the high pressure compression unit and is ultimately sent to a carbon dioxide sequestration.

The gas dryer 70 has a regeneration system 120 to intermittently regenerate the water vapor adsorption capacity of the gas dryer 70. A supply conduit 122 is provided to provide system 120 regeneration gas. The regeneration system uses a portion of the carbon dioxide rich flue gas stream as the regeneration gas. A portion of the carbon dioxide rich flue gas stream used as the regeneration gas is extracted downstream of the flue gas condenser 36 and upstream of the gas dryer 70, as seen in the direction of flow of the flue gas. Preferably, a portion of the carbon dioxide rich flue gas stream used as the regeneration gas is extracted downstream of the flue gas condenser 36 and upstream of the compressor 41, as seen by the direction of flow of the flue gas. In the embodiment of Figure 2, it is used as a rich oxidation of the regeneration gas. The soot flow is extracted directly from the downstream of the flue gas condenser. The regeneration system 120 includes a heater 124 for heating the regeneration gas. Heating circuit 126 is coupled to heater 124 to circulate a heating medium, such as steam, in heater 124. The heated regeneration gas exits the heater 124 via a fluid communication conduit 128. A temperature sensor 130 is disposed in the conduit 128 to measure the temperature of the heated regeneration gas. A valve 132 is disposed in the heating circuit 126 to control the flow of the heating medium to the heater 124. Temperature sensor 130 controls valve 132 to provide an appropriate amount of heating medium. To regenerate the charge 112 material of the gas dryer 70, the heater 124 typically heats the regeneration gas to a temperature of between about 130 ° C and 315 ° C. In one embodiment, wherein the 3A or 4A molecular sieve comprising hydrated aluminosilicate is used as a desiccant, the regeneration temperature is preferably in the range of from about 200 °C to 290 °C. Regenerative valves 134, 136 are disposed on conduits 128 and 148, respectively. During the regeneration sequence, valves 134, 136 are opened to pass the regeneration gas through gas dryer 70.

Gas dryer isolation valves 142, 144 are disposed on conduits 68, 72, respectively. During the regeneration sequence, valves 142, 144 are closed to isolate gas dryer 70, and heated regeneration gas is supplied from regeneration and heating system 120 to gas dryer 70 via conduit 146 in fluid communication with conduit 128. Heating the regeneration gas 112 of the packing material, resulting in solutions and steam and NO _x adsorbed. Containing water vapor and desorption of the NO _x regeneration waste gas leaving the gas drier 70 via line 148. The conduit 148 delivers the spent regeneration gas to the combustion zone of the boiler for combustion with the fuel provided via the supply conduit 14 and the oxygen of the mixed recycle flue gas provided via conduit 20.

It should be understood that when the valves 142, 144 are closed, the carbon dioxide rich gas is not available. The gas dryer 70 is passed through a conduit 68. According to an embodiment, GPU 40 may have two parallel gas dryers 70 that, when operating in one of the parallel gas dryers 70, regenerate another parallel gas dryer 70. According to another embodiment, the carbon dioxide rich flue gas may be vented to the atmosphere during regeneration of the packing 112 of the gas dryer 70.

Figure 3 illustrates one embodiment of GPU 40 in more detail. It should be understood that the diagram of FIG. 3 is a schematic diagram, and the GPU may further include a gas purification device or the like.

GPU 40 includes at least one compressor having at least one and typically two to ten compression stages to compress and purify the carbon dioxide rich flue gas. Each compression stage can be configured in a separate unit. Alternatively, as shown in Figure 3, several compression stages can be operated by a common drive. The GPU 40 of FIG. 3 includes a compressor 41 having a first compression stage 42, a second compression stage 44, and a third compression stage 46. The first through 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 include an intermediate cooling unit 56 located downstream of some or all of the compression stages 42, 44, 46. In the GPU 40 of FIG. 3, an optional intermediate cooling unit 56 is located downstream of the first compression stage 42. The intermediate cooling unit 56 includes a gas cooler 55 and a gas-liquid separator 57. The gas cooler 55 cools the compressed carbon dioxide rich flue gas to a temperature below the dew point temperature of the compressed carbon dioxide rich flue gas relative to water, resulting in condensation of water vapor in the flue gas. The gas-liquid separator 57 separates the water droplets generated by the condensation caused by the cooling of the gas in the gas cooler 55 from the residual gas.

GPU 40 may include a downstream of one of compression stages 42, 44, 46. Mercury adsorber 60. In the embodiment of FIG. 3, the mercury adsorber 60 is disposed downstream of the third compression stage 46, downstream of the low pressure compression unit 48. It should be appreciated that the mercury adsorber 60 can also be disposed downstream of the first compression stage 42 or downstream of the second compression stage 44.

The partially purified carbon dioxide rich flue gas enters GPU 40 via conduit 38 and is introduced into first compression stage 42. The conduit 54 transports compressed gas from the first compression stage 42 to the second compression stage 44 via the intermediate cooling unit 56 as appropriate. The conduit 58 transports compressed gas from the second compression stage 44 to the third compression stage 46 via an intermediate cooling unit, not shown, as appropriate. The conduit 66 delivers compressed gas from the third compression stage 46 to the mercury adsorber 60. The conduit 68 delivers compressed gas from the mercury adsorber 60 to the gas dryer 70.

The mercury adsorber 60 has a filler comprising a mercury adsorbent having an affinity for mercury. The adsorbent can, for example, be a sulfur impregnated activated carbon, or another substance known to have an affinity for mercury itself. Thus, as the compressed carbon dioxide-rich flue gas passes through the packing, at least a portion of the mercury content of the gas will adsorb to the mercury adsorbent of the packing. The compressed carbon dioxide rich flue gas from which at least a portion of the mercury content has been removed is delivered to the gas dryer 70 via the fluid communication conduit 68.

When the filler adsorbs mercury according to its adsorption capacity, the waste filler is replaced with a new filler. According to an embodiment, GPU 40 may have two parallel mercury adsorbers 60 that, when operating in one of the parallel adsorbers 60, replace the other parallel adsorber packing. According to another embodiment, the carbon dioxide rich flue gas may be vented to the atmosphere during the replacement of the filler.

GPU 40 includes at least one gas dryer 70. A gas dryer 70 is used to remove at least a portion of the residual water vapor content of the compressed gas. Similarly, the compressed gas is at least partially adsorbed on the NO _x content of the gas drier.

The compressed carbon dioxide rich flue gas from the mercury adsorber 60 enters the gas dryer 70 via a fluid communication conduit 68. The gas dryer 70 has a packing 112 comprising a molecular sieve having an affinity for water vapor. The molecular sieve may, for example, comprise an aluminosilicate mineral, clay, porous glass, microporous charcoal, zeolite, activated carbon or a synthetic compound having a loose structure through which small molecules such as water vapor can diffuse and adsorb, or combination. In one embodiment, the molecular sieve comprises hydrated aluminosilicate. The molecular sieve can be, for example, a 3A or 4A molecular sieve. Thus, as the compressed carbon dioxide rich flue gas passes through the packing 112, at least a portion of the water vapor content of the gas will adsorb to the molecular sieve of the packing 112.

In one example, the compressed carbon dioxide rich flue gas exiting gas dryer 70 via line 72 has a temperature of 30 ° C and an absolute pressure just below 30 bar absolute. NO _x gas and water vapor content also decreased. Such a gas adapted in a CO ₂ liquefaction unit 74 and the high pressure compression unit 76 for further processing and ultimately sent to the carbon dioxide storage 78 via pipe 80, as shown in FIG. 3. For example, the heat exchanger (also referred to as a cooling tank) of the CO ₂ liquefaction unit 74 can be made of aluminum.

The gas dryer 70 has a regeneration system 120 to intermittently regenerate the water vapor adsorption capacity of the gas dryer 70. A supply conduit 122 is provided to provide system 120 regeneration gas. The regeneration system uses a portion of the carbon dioxide rich flue gas stream as the regeneration gas. The carbon dioxide-rich flue gas stream used as the regeneration gas is extracted from the downstream of the flue gas condenser and upstream of the gas dryer, such as the flow direction of the flue gas. see. In the embodiment of Figure 3, the carbon dioxide rich flue gas stream used as the regeneration gas is extracted directly from the downstream of the flue gas condenser. The regeneration system 120 includes a heater 124 that heats the regeneration gas. Heating circuit 126 is coupled to heater 124 to circulate a heating medium, such as steam, in heater 124. The heated regeneration gas exits the heater 124 via a fluid communication conduit 128. A temperature sensor 130 is disposed in the conduit 128 to measure the temperature of the heated regeneration gas. A valve 132 is disposed in the heating circuit 126 to control the flow of the heating medium to the heater 124. Temperature sensor 130 controls valve 132 to provide an appropriate amount of heating medium. To regenerate the material 112 of the gas dryer 70, the heater 124 typically heats the regeneration gas to a temperature of between about 130 ° C and 315 ° C. In one embodiment, wherein the 3A or 4A molecular sieve comprising hydrated aluminosilicate is used as a desiccant, the regeneration temperature is preferably in the range of from about 200 °C to 290 °C.

Regenerative valves 134, 136 are disposed on conduits 128 and 148, respectively. During the regeneration sequence, valves 134, 136 are opened to pass the regeneration gas through gas dryer 70.

Gas dryer isolation valves 142, 144 are disposed on conduits 68, 72, respectively. During the regeneration sequence, valves 142, 144 are closed to isolate gas dryer 70, and heated regeneration gas is supplied from regeneration and heating system 120 to gas dryer 70 via conduit 146 in fluid communication with conduit 128. A filler material 112 is heated regeneration gas, and water vapor and NO _x resulting in desorption. Containing water vapor and desorption of the NO _x regeneration waste gas leaving the gas drier 70 via line 148. The conduit 148 delivers the spent regeneration gas to the combustion zone of the boiler for combustion with the fuel provided via the supply conduit 14 and the oxygen of the mixed recycle flue gas provided via conduit 20.

It will be appreciated that the carbon dioxide rich gas does not pass through the gas dryer 70 via conduit 68 when the valves 142, 144 are closed. According to an embodiment, GPU 40 may have two parallel gas dryers 70 that, when operating in one of the parallel gas dryers 70, regenerate another parallel gas dryer 70. According to another embodiment, the carbon dioxide rich flue gas may be vented to the atmosphere during regeneration of the packing 112 of the gas dryer 70.

While the invention has been described with respect to the embodiments of the present invention, it will be understood In addition, many modifications may be made to adapt a particular situation or substance to the teachings of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments of the invention, Moreover, the use of the terms first, second, etc. does not denote any <RTIgt; </ RTI> order or importance. Instead, the terms first, second, etc. are used to distinguish different elements.

1‧‧‧Boiler system

2‧‧‧Boiler

4‧‧‧ Turbine Power Generation System

6‧‧‧Gas purification system

8‧‧‧dust removal filter

10‧‧‧ Wet scrubber

12‧‧‧fuel storage device

14‧‧‧Supply tube

16‧‧‧Oxygen source

18‧‧‧Supply pipeline

20‧‧‧ Pipes

22‧‧‧ steam pipe

24‧‧‧ Pipes

26‧‧‧ Pipes

28‧‧‧Circulating pump

30‧‧‧Slurry circulation tube

32‧‧‧ Pipes

33‧‧‧ gas distribution point

34‧‧‧ Pipes

36‧‧‧Fume condenser

37‧‧‧Processing tube

38‧‧‧ Pipes

40‧‧‧GPU

41‧‧‧Compressor

42‧‧‧First compression stage

44‧‧‧second compression stage

46‧‧‧ third compression stage

48‧‧‧Low compression unit

50‧‧‧ drive shaft

52‧‧‧Motor

54‧‧‧ Pipes

55‧‧‧ gas cooler

56‧‧‧Intermediate cooling unit

57‧‧‧ gas-liquid separator

60‧‧‧ Mercury adsorber

64‧‧‧ Pipes

66‧‧‧ Pipes

68‧‧‧ Pipes

70‧‧‧ gas dryer

72‧‧‧ Pipes

74‧‧‧CO ₂ liquefaction unit

76‧‧‧High pressure compression unit

78‧‧‧Carbon dioxide storage

80‧‧‧ Pipes

112‧‧‧Filling

120‧‧‧Regeneration system

122‧‧‧Supply pipeline

124‧‧‧heater

126‧‧‧heating circuit

128‧‧‧ Pipes

130‧‧‧temperature sensor

132‧‧‧ Valve

134‧‧‧Regeneration valve

136‧‧‧Regeneration valve

142‧‧‧Isolation valve

144‧‧‧Isolation valve

146‧‧‧ Pipes

148‧‧‧ Pipes

Figure 1 schematically depicts an embodiment of a boiler system.

Figure 2 schematically depicts an embodiment of a gas dryer.

FIG. 3 schematically depicts one embodiment of a GPU.

1‧‧‧Boiler system

2‧‧‧Boiler

4‧‧‧ Turbine Power Generation System

6‧‧‧Gas purification system

8‧‧‧dust removal filter

10‧‧‧ Wet scrubber

12‧‧‧fuel storage device

14‧‧‧Supply tube

16‧‧‧Oxygen source

18‧‧‧Supply pipeline

20‧‧‧ Pipes

22‧‧‧ steam pipe

24‧‧‧ Pipes

26‧‧‧ Pipes

28‧‧‧Circulating pump

30‧‧‧Slurry circulation tube

32‧‧‧ Pipes

33‧‧‧ gas distribution point

34‧‧‧ Pipes

36‧‧‧Fume condenser

37‧‧‧Processing tube

38‧‧‧ Pipes

40‧‧‧GPU

80‧‧‧ Pipes

122‧‧‧Supply pipeline

148‧‧‧ Pipes

Claims (10)

A method for purifying carbon dioxide-rich flue gas produced by burning a fuel in a boiler in the presence of an oxygen-containing gas, the method comprising: removing at least a portion of water content of the flue gas in a flue gas condenser; and the flue gas condenser Compressing carbon dioxide-rich flue gas in a downstream configured compressor, as seen in the direction of flow of the flue gas; using molecular sieves in a gas dryer disposed downstream of the compressor to remove at least a portion of residual water content in the flue gas; by extracting a flue gas condenser section upstream and downstream of the carbon dioxide rich flue gas of the compressor, the extracted flue gas is heated to a temperature suitable for regeneration of the molecular sieve, so that the flue gas is heated in order to desorb water and gas dryer through a sieve of the NO _x regeneration of the molecular sieve; and adsorbed water-containing solutions of NO _x and CO rich flue gas is returned to the boiler. The method of claim 1, wherein the temperature is in the range of 130 ° C to 315 ° C. The method of claim 2, wherein the temperature is in the range of from 200 °C to 290 °C. The method of claim 1, further comprising subjecting the flue gas stream to dust removal upstream of the flue gas condenser, as seen in the direction of flow of the flue gas. The method of claim 1, further comprising subjecting the flue gas stream to sulfur dioxide removal upstream of the flue gas condenser, as seen in the direction of flow of the flue gas. 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 method for removing at least a portion of water content of the flue gas a flue gas condenser (36); a compressor (41) disposed downstream of the flue gas condenser for compressing the carbon dioxide rich flue gas, as seen in the flow direction of the carbon dioxide rich flue gas; and a method for removing at least the flue gas the water content of the residual portion of the compressor (41) arranged downstream of the molecular sieve-containing gas dryer (70), the direction of flow as seen in the carbon dioxide rich flue gas; water desorption of a gas and the molecular sieve of the NO _x regeneration system for drier (120); the gas dryer regeneration system (120) includes: a portion of a carbon dioxide-rich flue gas stream downstream of the flue gas condenser (36) and upstream of the compressor (41) and directing the portion of the carbon dioxide-rich flue gas stream The gas dryer (70) is returned to the gas conduit (122) of the boiler (2), and a portion is used to heat the extracted portion of the carbon dioxide-rich flue gas to be suitable for molecular sieve regeneration before it enters the gas dryer (70) The temperature of the flue gas heater (124). The flue gas treatment system of claim 6, wherein the temperature is in the range of 130 ° C to 315 ° C. The flue gas treatment system of claim 7, wherein the temperature is in the range of from 200 °C to 290 °C. The flue gas treatment system of claim 6, further comprising a dust removal filter (8) disposed upstream of the flue gas condenser (36), as seen in the direction of flow of the flue gas. The flue gas treatment system of claim 6 further comprising a scrubber (10) upstream of the flue gas condenser (36) for removing sulfur dioxide, as seen in the direction of flow of the flue gas.