TW201313302A - Method and system for NOx reduction in flue gas - Google Patents

Abstract

The present invention relates to a method of cleaning a carbon dioxide rich flue gas stream containing oxygen, said method comprising: heating the flue gas stream to a temperature suitable for selective catalytic reduction (SCR) of NOx; and reducing at least some of the NOx in the heated flue gas stream to N2 by SCR; characterized in that said heating of the flue gas stream comprises removal of residual oxygen contained in the flue gas by catalytic oxidation of a suitable carburant. The present invention further relates to a gas processing unit.

Description

Method and system for reducing NOx in flue gas

This invention relates to a method of cleaning a carbon dioxide-rich oxygen-containing flue gas stream.

The invention further relates to a gas processing unit for cleaning a carbon dioxide-rich oxygen-containing flue gas stream.

When a fuel such as coal, petroleum, peat, waste, or the like is burned in a combustion apparatus such as a power plant, a hot process gas is generated, which process gas contains, in particular, carbon dioxide CO ₂ (more than other components). As environmental demands have increased, a number of processes have been developed for self-contained gas removal of carbon dioxide. One such process is the so-called oxygen-burning process. In an oxygen combustion process, a fuel such as one of the above fuels is combusted in the presence of a nitrogen-depleted gas. Oxygen supplied by an oxygen source is supplied to a boiler in which oxygen oxidizes the fuel. A carbon dioxide-rich flue gas is produced in an oxy-combustion process that can be treated using a variety of CO ₂ capture technologies to reduce carbon dioxide emissions to the atmosphere.

CO ₂ capture typically involves cooling or compressing and cooling the flue gas to separate CO _{2 in} liquid or solid form from non-condensable flue gas components (eg, N ₂ and O ₂ ).

It is often necessary to clean the carbon dioxide-rich flue gas prior to CO ₂ capture. Gas cleaning operations can typically involve the removal of dust, sulfur compounds, metals, nitrogen oxides, and the like.

To prevent ice formation in the heat exchanger used in the CO ₂ capture process, the wet flue gas must also be dried prior to being cooled. In order to achieve the desired drying of the flue gas, an adsorption dryer can be employed. The adsorption dryer uses an adsorbent such as a molecular sieve to effectively remove water from the flue gas. A problem with many adsorption dryers is that adsorbents such as molecular sieves may be sensitive to acid degradation of acids formed by adsorbents and acid formed by water. This acid degradation can severely reduce the useful life of the adsorbent.

Selective catalytic reduction (SCR) catalyst system by means of nitrogen oxides (also referred to as NO _X) is converted into diatomic nitrogen and water N H _{2 2} O of methods. A gaseous reducing medium (usually anhydrous ammonia, ammonia or urea) is added to the flue gas or exhaust gas stream and adsorbed onto the catalyst. NO _X reduction reaction occurs when the gas passes through the catalyst chamber. Ammonia or other reducing medium is injected and mixed with the gas prior to entering the catalyst chamber. The SCR reaction is usually carried out at a temperature ranging from 200 ° C to 500 ° C. The minimum effective temperature depends on, for example, the gas composition and the catalyst geometry. The SCR catalyst is made from a variety of ceramic materials such as titanium oxide used as a carrier, and the active catalytic component is usually an oxide of an alkali metal such as vanadium and tungsten, a zeolite, and/or a plurality of noble metals. Each catalyst component has advantages and disadvantages.

The problem with SCR is that the catalyst can become clogged due to the introduction of soot, fly ash, and other particulate materials such as metals. This blockage reduces the efficiency and useful life of the SCR catalyst.

It is an object of the present invention to provide a method and system for cleaning a carbon dioxide-rich oxygen-containing flue gas stream, for example, from a so-called oxygen-burning system, which solves at least one of the above problems.

In addition to carbon dioxide, the carbon dioxide rich flue gas stream typically comprises water vapor and NO _X, NO _X and such vapor must be at least partially removed from the flue gas before the carbon dioxide capture. The carbon dioxide rich flue gas stream further includes residual oxygen.

Selective catalytic reduction (SCR) requires, for example, a high temperature in the range of 190 ° C to 600 ° C to make it efficient. For example, in a power plant, the SCR step (when present in prior art gas treatment systems) typically follows the combustion step (where the flue gas stream is already at a high temperature) or shortly thereafter.

In the gas cleaning methods and systems presented herein, the SCR step is replaced with the use of a cooled flue gas stream and involves heating the flue gas stream to a temperature suitable for SCR. More specifically, the SCR step can be carried out in a gas compression and purification unit of an oxygen-burning system in which carbon dioxide-rich flue gas is compressed and cooled in a series of compression stages and finally separated in liquid form.

Explanation of the aspects herein provides a method of cleaning the carbon dioxide rich flue gas containing oxygen, the method comprising: heating the flue gas stream is adapted to the selective catalytic reduction of NO _X (SCR) of the temperature; and by the SCR via reduction in the flue gas stream is heated to at least some of the NO _X to N _2; characterized in that the heating of the flue gas by an oxidation catalyst comprising a suitable carbon agent of removing residual oxygen contained in the flue gas.

System temperature is generally adapted to the NO _X selective catalytic reduction (SCR) is in the range of 190 deg.] C to 600 deg.] C, for example in the range of 200 ℃ to 350 deg.] C. Heating of the flue gas stream can be achieved using a suitable conventional electric or steam heating system. However, a significant disadvantage of such conventional heating systems is that they increase the overall high quality energy requirements of the process. It has been found residual flue gas stream may be enriched in carbon dioxide in the flue gas stream for oxygen was heated to the desired degree of removal of NO _X by the SCR. This can be done by reacting residual oxygen contained in the flue gas with a suitable recarburizer using a catalyst system. The recarburizer is added to the flue gas stream upstream of the catalyst system and the oxygen in the flue gas is then removed in the catalyst bed of the catalyst system by oxidation of the recarburizer. The temperature of the flue gas is increased by the heat generated by the exothermic reaction. The temperature increase can be controlled by adjusting the amount of recarburant added to the flue gas. According to an embodiment, an exothermic reaction increasing the temperature of the flue gas temperature is adapted to the NO _X selective catalytic reduction (SCR) of, i.e. to a temperature in the range of 190 deg.] C to 600 deg.] C, the range of such deg.] C of 350 to 200 ℃ . The recarburizer can be any combustible gas, liquid or even solid material that is compatible with the catalyst system. The recarburizer can be, for example, hydrogen or a hydrocarbon. Examples of suitable recarburizers include hydrogen, natural gas, and methane, and mixtures thereof. Looking at the recarburizer, the desired catalytic oxidation temperature can be higher than the temperature required for NOx reduction. In this case, it is foreseen that the gas/gas heater cools the oxidation reactor outlet by heating the oxidation reactor feed.

According to an embodiment, the heating comprising: performed by indirect heat exchange with flue gas from the SCR exchange of the flue gas stream to produce a pre-heated to a first temperature; then heated to a ultra adapted NO _X by the pre-heating of the flue gas stream and The temperature of selective catalytic reduction (SCR) is characterized in that the superheating of the flue gas stream comprises catalytic removal of residual oxygen contained in the flue gas by oxidation of a suitable recarburizer.

Preheating the flue gas system using a flue gas stream generated from the SCR is advantageous because it reduces the amount of recarburizer required to superheat the preheated flue gas stream to a temperature suitable for selective catalytic reduction. the amount.

According to an embodiment, the flue gas cleaning method further comprises condensing the flue gas stream with the flue gas prior to heating the flue gas stream. Flue gas condensation can significantly reduce the total flue gas flow rate, thus reducing the required size of the downstream flue gas heater, SCR and dryer unit. The flue gas entering the FGC typically contains about 40% by volume water. The flue gas after FGC usually contains about 5% by volume of water. A further advantage of the FGC is the removal of the scrubbing liquid or slurry (e.g., lime slurry) from the flue gas from the sulfur dioxide removal step described above during condensation, thereby reducing the surface of the SCR catalyst and/or gas heater surface. Scale and / or blockage problems.

According to an embodiment, the method further comprises compressing the flue gas stream to an absolute pressure in the range of 2 to 55 bar prior to heating the flue gas stream. It has been found in the flue gas at a high pressure since almost all of NO _X in the NO ₂ in the form of lines are therefore preferred in the flue gas prior to the compression step SCR.

According to an embodiment, the method further comprises removing at least some of the water vapor by adsorption from the NO _X depletion flue gas stream in the adsorption dryer. In selective catalytic reduction, water is formed as a product. In a CO ₂ before the flue gas may be processed (e.g., by compression and cooling) to be separated, can advantageously be removed from the flue gas at least some of this water to prevent ice formation.

According to an embodiment, the SCR step is performed downstream of the compression step but upstream of the water removal step.

In some embodiments, the method further comprises carbon dioxide enriched flue gas before CO ₂ capture accepted mercury removal step. The mercury removal step is typically performed downstream of the compression step but upstream of the water removal step. When the mercury removal step is present, the SCR step can be performed between the compression step and the mercury removal step or between the mercury removal step and the water removal step. Performing the SCR step downstream of the mercury removal step will eliminate possible poisoning of the SCR catalyst caused by mercury entrained in the flue gas.

A gas processing unit (GPU) for treating a carbon dioxide rich flue gas stream typically can include a flue gas condenser (which is used to reduce the water content of the flue gas) and a gas compression and purification system (which is used for additional cleaning and The liquid form of CO _{2 is} then separated from the non-condensable flue gas components such as N ₂ and O ₂ ).

According to other aspects illustrated herein, a gas processing unit for cleaning a carbon dioxide-rich oxygen-containing flue gas stream is provided, the unit comprising: a flue gas heater configured to heat the flue gas stream to a suitable selective catalytic reduction of NO _X of temperature; selective catalytic reduction reactor (SCR reactor), which was configured to receive the heat from the flue gas heater flue gases by selective catalytic reduction and the heated at least some of the reduction of NO _X in the flue gas stream into N _2; characterized in that the flue gas heater comprising a carbon agent supply means and a catalyst system wherein the catalyst system is used for operation from a supply device carburant The recarburizer reduces residual oxygen contained in the flue gas.

According to an embodiment, the flue gas heater comprises: a flue gas preheater configured to heat the flue gas stream to a first temperature by indirect heat exchange with a flue gas stream exiting the SCR reactor; and a flue gas super heater, which was configured to be heated to a temperature suitable for the selective catalytic reduction of NO _X (SCR) of the flue gas stream through the pre-heating, characterized in that the flue gas comprises a super heater supplying carburant A device and a catalyst system, wherein the catalyst system is operative to reduce residual oxygen contained in the flue gas using a recarburant from the recarburizer supply.

Preheating the flue gas system using a flue gas stream produced from an SCR reactor is advantageous because it reduces the carbonation required to superheat the preheated flue gas stream to a temperature suitable for selective catalytic reduction. The amount of the agent.

According to an embodiment, the GPU further includes a flue gas condenser disposed upstream of the flue gas heater. Flue gas condensation can significantly reduce the total flue gas flow rate, thus reducing the required size of the downstream flue gas heater, SCR and dryer unit. The flue gas entering the FGC typically contains about 40% by volume water. The flue gas after FGC usually contains about 5% by volume of water. A further advantage of the FGC is the removal of the scrubbing liquid or slurry (e.g., lime slurry) from the flue gas from the sulfur dioxide removal step described above during condensation, thereby reducing the surface of the SCR catalyst and/or gas heater surface. Scale and / or blockage problems.

According to an embodiment, the GPU further includes a flue gas compressor disposed upstream of the flue gas heater. The flue gas compressor can preferably compress the flue gas to an absolute pressure in the range of 2 to 55 bar. It has been found in the flue gas at a high pressure since almost all of NO _X in the NO ₂ in the form of lines are therefore preferred compressed flue gas before the SCR reactor.

According to an embodiment, the GPU further includes an adsorption dryer configured to remove at least some of the water by adsorption from the NO _X depletion flue gas stream. In selective catalytic reduction, water is formed as a product. In a CO ₂ before the flue gas may be processed (e.g., by compression and cooling) to be separated, can advantageously be removed from the flue gas at least some of this water to prevent ice formation.

According to an embodiment, the SCR reactor is disposed downstream of the flue gas compressor but upstream of the adsorption dryer.

According to an embodiment, the GPU further comprises a mercury adsorption unit. The mercury adsorption unit is typically disposed downstream of the flue gas compressor but upstream of the adsorption dryer. When a mercury adsorption unit is present, the SCR reactor can be disposed between the flue gas compressor and the mercury adsorption unit or between the mercury adsorption unit and the adsorption dryer. Performing the SCR step downstream of the mercury removal step will eliminate possible poisoning of the SCR catalyst caused by mercury entrained in 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 description and claims.

Reference is now made to the various figures of the exemplary embodiments in which the

Figure 1 illustrates in more detail a gas processing unit (GPU). It should be appreciated that the illustration of FIG. 1 is a schematic diagram and that the GPU can include other devices for gas purification and the like.

The GPU 1 includes a flue gas condenser (FGC) 4 in which the flue gas is cooled at a temperature below the dew point of the flue gas and the heat released by the resulting condensate is recovered as low temperature heat. The water content of the flue gas can be reduced from, for example, 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 the pH and temperature in the flue gas condenser, flue gas condensation can also reduce the sulfur oxides SO _X in the flue gas. Sulfur oxides are trapped in the condensate formed and separated from the flue gas. In addition, the scrubbing liquid or slurry (eg, lime slurry) from the flue gas from the foregoing sulfur dioxide removal step is removed during condensation, thereby reducing fouling of the SCR catalyst and/or gas heater surface and/or Blocking problem.

The GPU 1 further includes at least one flue gas compressor 10. The compressor has at least one and typically 2 to 10 compression stages for compressing the cleaned carbon dioxide rich flue gas from the flue gas condenser 2. Each compression stage can be configured as a separate unit. Alternatively and as illustrated in Figure 1, several compression stages can be operated by sharing the drive shaft. The GPU 1 of FIG. 1 includes a compressor 10 having a first compression stage 12, a second compression stage 14, and a third compression stage 16. The first to third compression stages 12, 14, 16 together form the low voltage compression unit 18 of the GPU 1. The compression stages 12, 14, 16 are coupled to a common drive shaft 20 that is driven by a motor 22 of the compressor 10.

In addition, the low pressure compression unit 18 may also include an intermediate cooling unit 24 located downstream of the one or more compression stages 12, 14, 16. Therefore, the intermediate cooling unit 24 can be disposed downstream of the first and second compression stages 12 and 14 of the GPU 1 of FIG. One such optional intermediate cooling unit 24 can be illustrated downstream of the second compression stage 14. The intermediate cooling unit can be further configured to collect and dispose of any liquid condensate formed during compression and/or cooling.

During the compression of the flue gas, NO ₂ can be used as a catalyst to react to convert the sulfur oxide SO _X to its individual acid using liquid water. The acid formed can then be separated in an intermediate cooling unit 24 disposed downstream of the first and/or second compression stages. Thus, the low-pressure compression unit 18 may help to reduce the flue gas of SO _X.

GPU 1 may include at least one mercury adsorption unit 26 disposed downstream of one of compression stages 12, 14, 16. In the embodiment of FIG. 1, the mercury adsorption unit 26 is disposed downstream of the third compression stage 16, ie downstream of the low pressure compression unit 18. It will be appreciated that the mercury adsorption unit 26 can also be disposed downstream of the first compression stage 12 or downstream of the second compression stage 14. More than one mercury adsorption unit 26 may also be disposed in the GPU, such as a mercury adsorption unit downstream of the second compression stage 14 and a mercury adsorption unit downstream of the third compression stage 16. The mercury adsorption unit 26 is provided with a filler including a mercury adsorbent having a mercury affinity. The adsorbent can be, for example, activated carbon impregnated with sulfur or another material known to have the same affinity for mercury. Thus, as the compressed carbon dioxide-rich flue gas passes through the packing, at least a portion of the mercury in the gas will be adsorbed onto the mercury adsorbent of the packing.

The GPU 1 includes at least one selective catalytic reduction unit (SCR unit) 30. The SCR unit 30 is disposed upstream of the adsorption dryer 40 and can be disposed downstream of one of the compression stages 12, 14, 16 of the low pressure compression unit 18. In the embodiment of FIG. 1, the SCR unit is disposed downstream of the low pressure compression unit 18, ie, directly downstream of the third compression stage 16. An alternative configuration of the SCR unit (not shown in Figure 1) is included upstream of the low pressure compression unit 18 but between the flue gas condenser 4 and between the compression stages 12 and 14 of the low pressure compression unit 18 or between the compression stages 14 and 16. . Other configurations of the SCR unit in the GPU 1 upstream of the adsorption dryer 40 are also possible. In particular, in an embodiment of a gas treatment unit comprising a mercury adsorption unit, the mercury adsorption unit can be disposed downstream of the flue gas compressor but upstream of the adsorption dryer. When the mercury adsorption unit is present downstream of the flue gas compressor but upstream of the adsorption dryer, the SCR single can be The element is disposed between the flue gas compressor and the mercury adsorption unit or between the mercury adsorption unit and the adsorption dryer. In the embodiment of FIG. 1, the SCR unit 30 is disposed between the mercury adsorption unit 26 and the adsorption dryer 40. Performing an SCR step downstream of the mercury removal step eliminates possible poisoning of the SCR catalyst caused by mercury entrained in the flue gas. The SCR unit 30 is explained in detail below with reference to FIG.

The GPU 1 further includes an adsorption dryer 40 that is operative to remove at least a portion of the water vapor in the flue gas.

The adsorption dryer 40 is disposed downstream of the SCR unit 30 but upstream of the CO ₂ separation unit 50. As shown in FIG. 1, the sorption dryer 40 can be disposed directly downstream of the SCR unit 30 such that, as appropriate, the flue gas stream in a suitable cooling gas cooler (not shown) and/or from one or more (eg, After extracting heat from the flue gas stream in the flue gas economizer for preheating the boiler feed water, the flue gas treated by the SCR unit 30 is directly sent to the adsorption dryer 40.

The adsorption dryer 40 has a flue gas inlet and a flue gas outlet and contains an adsorbent or a desiccant capable of adsorbing water molecules from the gas stream. The adsorbent may be a molecular sieve having a pore size suitable for adsorbing water, such as a molecular sieve having a pore size in the range of 3 Å to 5 Å.

The adsorption dryer 40 can be provided with a regeneration and heating system (not shown) for intermittently regenerating the water vapor adsorption capacity of the adsorption dryer 40. The supply conduit is configured to supply regeneration gas to the system. The regeneration gas is preferably an inert gas that does not react with the filler of the adsorption dryer. Examples of suitable gases include nitrogen or another inert gas that preferably maintains a low amount of mercury and water vapor. Preferably, an inert exhaust gas which generally includes nitrogen as a main component and is separated from carbon dioxide in the CO ₂ separation unit 50 is used as the regeneration gas. The regeneration system includes a heater adapted to heat the regeneration gas. A heating circuit is connected to the heater for circulating a heating medium such as steam in the heater. For the filler material of the regeneration gas dryer 40, the heater typically heats the regeneration gas to a temperature of between about 120 °C and 300 °C. The heated regeneration gas is supplied to the gas dryer 40 from the regeneration and heating system during the regeneration sequence. The regeneration gas heats the material of the packing and desorbs the water vapor.

According to an embodiment, GPU 1 may be provided with two parallel gas dryers 40, wherein one of the parallel gas dryers is in an operational state and the other parallel gas dryer is regenerated. According to another embodiment, the carbon dioxide-rich flue gas can be vented to the atmosphere during regeneration of the packing of the gas dryer.

Figure 2 illustrates the SCR unit 30 in more detail. The carbon dioxide-rich flue gas that has been condensed by the flue gas enters the SCR unit 30 via a fluidly connected conduit 19. Depending on the position of the SCR and dryer unit with respect to the compression stage of the low pressure compression unit 18, the carbon dioxide rich flue gas may be at substantially atmospheric pressure or a pressure of 2 to 55 bar absolute and is typically between 20 and 70 °C. At the temperature. The preferred operating temperature of the SCR reactor is typically in the range of from 190 °C to 600 °C.

The SCR unit 30 includes an SCR reactor 32 having a flue gas inlet 33, a flue gas outlet 34, and a catalyst bed 35 including an SCR catalyst. The SCR catalyst can be made from a ceramic material such as titanium oxide and at least one active catalytic component of an oxide which is usually an alkali metal such as vanadium or tungsten, a zeolite or a noble metal. The SCR unit 30 further includes means for injecting a gaseous reducing medium (typically anhydrous ammonia, ammonia or urea) into the flue gas of the SCR reactor 32. The medium supply device 36 is restored.

SCR unit 30 further comprises a flue gas heater 60, the heater flue gas through the flue gas stream configured to selectively heated to a temperature suitable for the catalytic reduction of NO _X. The flue gas heater 60 includes a recarburizer supply device 61 and a catalyst system 62, wherein the catalyst system 62 is operative to remove the flue gas contained in the flue gas using a recarburant from the recarburizer supply device 61. Residual oxygen. Catalyst system 62 includes a flue gas inlet 63, a flue gas outlet 64, and a catalyst bed 65. The recarburizer is added to the flue gas stream inside or upstream of the catalyst system 62, and then the oxygen in the flue gas is removed in the catalyst bed 65 of the catalyst system 62 upon oxidation of the recarburizer. The temperature of the flue gas is increased by the heat generated by the exothermic reaction. The temperature increase can be controlled by adjusting the amount of recarburant added to the flue gas (e.g., using a temperature control valve 66 having a temperature sensor disposed downstream of the flue gas outlet 64). According to an embodiment, an exothermic reaction increasing the temperature of the flue gas temperature is adapted to the NO _X selective catalytic reduction (SCR), namely in the range of 190 deg.] C to 600 deg.] C, e.g. in the range of 350 to 200 ℃ deg.] C on. The recarburizer can be any combustible gas, liquid or even solid material that is compatible with the catalyst system. Examples of suitable recarburizers include hydrogen and other low sulfur recarburizers such as natural gas and methane. In the case of methane, the desired catalytic oxidation temperature can be higher than the temperature required for SCR operation. In this case, it is foreseen that the gas/gas heater cools the oxidation reactor effluent. The catalyst system 62 of the flue gas heater 60 can comprise a suitable reaction vessel containing any suitable composition (e.g., in the form of a catalytic metal composition on a support). The catalytic metal composition can include, for example, platinum, palladium, platinum/ruthenium, or any other catalytically active metal species or composition to effectively effect a catalytic reduction operation. The catalytic metal composition can include, for example, a system of doping platinum or palladium. The catalytic metal composition can be provided on a suitable support, such as a crimped metal foil, monolithic support or other support medium and/or configuration.

Flue gas heater 60 may further include one or more heat exchangers 67, 68 that are configured to use flue gas exiting SCR reactor 32 or catalyst system 62 as a heating medium for Preheat the flue gas before heating in the flue gas heater.

The reducing medium is added to the heated flue gas fed to the SCR unit 30. The reducing medium can usually be anhydrous ammonia, ammonia or urea. The reducing medium can be added to the flue gas stream via a reducing medium supply device 36, for example, after preheating or after superheating (as shown in Figure 2). A reducing medium, such as ammonia, is mixed with the flue gas stream and adsorbed onto the SCR catalyst 35 in the SCR reactor 32. SCR reactor 32 by selective catalytic reduction to convert to N ₂ in the flue gas stream heated at least some of the NO _X.

Referring to Figure 1, during operation, carbon dioxide rich flue gas enters GPU 1 via conduit 2 and is introduced into FGC 4. The carbon dioxide-rich flue gas having a reduced water content exits the FGC 4 via conduit 6.

The conduit 6 delivers a carbon dioxide-rich flue gas having a reduced water content to the first compression stage 12. The conduit 13 transfers compressed gas from the first compression stage 12 to the second compression stage 14 via an intermediate cooling unit, not shown, as appropriate. The conduit 15 transfers compressed gas from the second compression stage 14 to the third compression stage 16 via the intermediate cooling unit 24 as appropriate. The conduits 17, 19 transfer compressed gas from the third compression stage 16 to the SCR unit 30 via the mercury adsorption unit 26.

In the SCR unit 30, the flue gas is preheated using hot flue gas exiting the SCR reactor 32 and/or the catalyst system 62 as a heating medium, as appropriate. The flue gas is then mixed with the recarburizer from the recarburizer supply 61 and delivered to the catalyst system 62. In the catalyst system 62, the recarburizer is oxidized by oxygen in the flue gas. The temperature of the flue gas is increased by the heat generated by the exothermic reaction. The hot flue gas from the catalytic system 62 and the reducing agent from the reducing agent supply device 36 and transferred to the mixing of the SCR reactor 32, which will be present in the flue gas of at least a portion of NO _X reduction into N _2. Then via a conduit 21 from the unit 30 of the NO _X SCR depleted flue gas stream 40 transferred to the adsorption dryer. The GPU 1 may optionally include a flue gas economizer (not shown) disposed between the SCR unit 30 and the adsorption dryer 40, and the flue gas economizer is configured to use, for example, boiler feed water from the SCR unit. The flue gas stream recovers heat. The adsorption dryer 40 is provided with a filler including a water vapor adsorbent, which is also referred to as a desiccant and has an affinity for water vapor. The desiccant can be, for example, silicone, calcium sulfate, calcium chloride, smectite clay, molecular sieves or another material known to be useful as a desiccant. Thus, as the further cooled carbon dioxide-rich flue gas passes through the packing, at least a portion of the water vapor in the gas will be adsorbed onto the desiccant of the packing.

Since adsorption drier 40 to the transfer of a selectable other GPU unit duct 23 has been removed, and compressing at least a portion of the NO _X content of the gas via the water. Examples of such optional other units of GPU 1 include a non-condensable gas removal unit (eg, CO ₂ separation unit 50) in which a heat exchanger (generally referred to as a cold box) cools the gas to liquefy carbon dioxide, thereby The carbon dioxide can be separated from a gas such as nitrogen that is not liquefied like carbon dioxide at the same temperature.

In addition, GPU 1 may include a high pressure compression unit 52 disposed downstream of CO ₂ separation unit 50 (as seen with respect to the direction of carbon dioxide transport) and including one or more compression stages for compressing carbon dioxide to a suitable pressure for isolation. . High pressure gas compressed in the compression unit 52, may be in the supercritical or liquid state of the carbon dioxide delivered to the compressed CO ₂ separator 54 sites.

It will be appreciated that many variations of the above-described embodiments are possible within the scope of the appended claims. Specifically, reference may be appreciated that the general direction of flow of the flue gas stream, the SCR and the dryer unit is disposed downstream of the condenser and dust removal unit and the flue gas are still in many different positions upstream of the CO ₂ separation unit.

Have been described above for _X may comprise how to remove the NO SCR reactor and a gas purification system of a flue gas heater is integrated GPU portion 1-2 of FIG illustrated illustration. It will be appreciated that this type of gas purification system and method of operation can also be integrated into other types of processes that require oxygen removal from a carbon dioxide rich flue gas stream. In addition, gas purification systems of the above type may also be integrated into the GPU in addition to those described above.

Although the present invention has been described with reference to a number of preferred embodiments thereof, those skilled in the art should understand that various changes can be made in the embodiments without departing from the scope of the invention. Elements. In addition, many modifications may be made to the teachings of the present invention without departing from the scope of the invention. Therefore, the present invention is not intended to be limited to the specific embodiments disclosed as the preferred embodiment of the invention. In addition, the terms first, second, etc. The use of the terms does not denote any order or importance, and the terms first, second, etc. are used to distinguish one element from another.

1‧‧‧Gas Handling Unit

2‧‧‧ catheter

4‧‧‧ Flue gas condenser

6‧‧‧ catheter

10‧‧‧ Flue gas compressor

12‧‧‧First compression stage

13‧‧‧ catheter

14‧‧‧second compression stage

15‧‧‧ catheter

16‧‧‧ third compression stage

17‧‧‧ catheter

18‧‧‧Low compression unit

19‧‧‧ catheter

20‧‧‧Shared drive shaft

21‧‧‧ catheter

22‧‧‧Motor

23‧‧‧ catheter

24‧‧‧Intermediate cooling unit

26‧‧‧ Mercury adsorption unit

30‧‧‧Selective catalytic reduction unit

32‧‧‧SCR reactor

33‧‧‧Fume gas inlet

34‧‧‧ flue gas outlet

35‧‧‧Tactile bed

36‧‧‧Reducing medium supply device

40‧‧‧Adsorption dryer

50‧‧‧CO ₂ separation unit

52‧‧‧High pressure compression unit

54‧‧‧CO ₂ isolation site

60‧‧‧ Flue gas heater

61‧‧‧Recarburizer supply unit

62‧‧‧catalyst system

63‧‧‧Fume gas inlet

64‧‧‧ Flue gas export

65‧‧‧Tactile bed

66‧‧‧temperature control valve

67‧‧‧ heat exchanger

68‧‧‧ heat exchanger

FIG. 1 schematically illustrates an embodiment of a GPU.

Figure 2 schematically illustrates an embodiment of a gas heater and SCR system.

19‧‧‧ catheter

21‧‧‧ catheter

30‧‧‧Selective catalytic reduction unit

32‧‧‧SCR reactor

33‧‧‧Fume gas inlet

34‧‧‧ flue gas outlet

35‧‧‧Tactile bed

36‧‧‧Reducing medium supply device

60‧‧‧ Flue gas heater

61‧‧‧Recarburizer supply unit

62‧‧‧catalyst system

63‧‧‧Fume gas inlet

64‧‧‧ Flue gas export

65‧‧‧Tactile bed

66‧‧‧temperature control valve

67‧‧‧ heat exchanger

68‧‧‧ heat exchanger

Claims (12)

A cleaning method of carbon dioxide, oxygen-enriched gas stream of flue gas, the method comprising: heating the flue gas stream to a temperature suitable for the selective catalytic reduction of NO _X (SCR) of; the SCR and heated by the smoke the secondary air flow to restore at least some of the NO _X to N _2; characterized in that the heating of the flue gas stream comprising carbon agent using a suitable catalytic reduction of the residual oxygen contained in the flue gas. The method of claim 1, wherein the heating comprises: preheating the flue gas stream to a first temperature by indirect heat exchange with the flue gas stream generated from the SCR; and then the preheated flue ultra stream to a temperature suitable for the NO _X selective catalytic reduction (SCR) of which the flue gas stream of the superheated carburant comprises using a suitable catalytic reduction of the residual oxygen contained in the flue gas. The method of any of the preceding claims, wherein the recarburizing agent is selected from the group consisting of hydrogen, methane, and natural gas or mixtures thereof. The method according to any one of the preceding items request, wherein the temperature coefficient of the NO _X selective adapted catalytic reduction (SCR) is in the range of 190 deg.] C to 600 deg.] C, for example in the range of 200 ℃ to 350 ℃. The method of any of the preceding claims, further comprising condensing the flue gas stream with flue gas prior to heating the flue gas stream. The method of any of the preceding claims, further comprising heating the The flue gas stream is compressed prior to the flue gas stream to an absolute pressure in the range of 2 to 55 bar. The method of any of the preceding claims, further comprising removing at least some of the water vapor from the NO _X depletion flue gas stream by adsorption in an adsorption dryer. A method for cleaning carbon dioxide-enriched gas treatment unit of the oxygen-containing flue gas stream, the unit comprising: a flue gas heater, which is heated by the flue gas stream to a configuration adapted to the selective catalytic reduction of the NO _X a temperature; a selective catalytic reduction reactor (SCR reactor) configured to receive heated flue gas from the flue gas heater and to at least heat the heated flue gas stream by selective catalytic reduction Some of the NO _X is reduced to N _2; characterized in that the flue gas heater comprising a carbon agent supply means and a catalyst system wherein the catalyst system is operative to increase the gain from the use of carbon-agent supplying device carbon agent The residual oxygen contained in the flue gas is reduced. The gas processing unit of claim 8, wherein the flue gas heater comprises: a flue gas preheater configured to indirectly exchange heat with the flue gas stream exiting the SCR reactor. gas stream is heated to a first temperature; super heater and the flue gas, which is configured by the temperature-adapted to the selective catalytic reduction of NO _X (SCR) of the pre-heating of the flue gas stream to heat, wherein the flue The gas superheater includes a recarburizer supply device and a catalyst system, wherein the catalyst system is operative to reduce residual oxygen contained in the flue gas using a recarburant from the recarburizer supply. The gas processing unit of any one of claims 8 to 9, further comprising a flue gas condenser disposed upstream of the flue gas heater. The gas processing unit of any one of claims 8 to 10, further comprising a flue gas compressor disposed upstream of the flue gas heater. The gas processing unit of any one of claims 8 to 11, further comprising an adsorption dryer configured to remove at least some of the water by adsorption from the NO _X depletion flue gas stream.