An oxygen-enriched combustion circulating flue gas desulfurization system and method

Abstract

This invention discloses an oxygen-enriched combustion circulating flue gas desulfurization system and method, which employs pressure swing adsorption (PSA) for secondary desulfurization of flue gas based on a conventional primary desulfurization system. The system mainly includes a desulfurization chamber, a pressurized adsorption chamber, and a vacuum desorption chamber. The flue gas, after denitrification, undergoes primary desulfurization in the desulfurization chamber and is then sent to the pressurized adsorption chamber to remove residual SO₂. x The adsorbent undergoes material regeneration within the vacuum desorption chamber, and the desorbed SO₂ is then desorbed. x The gas is then sent to the desorption chamber for processing. The oxygen-enriched combustion circulating flue gas desulfurization system can achieve efficient desulfurization of flue gas, meet the operating requirements of oxygen-enriched combustion boilers, and improve the purity of carbon dioxide capture.

Description

Technical Field

[0001] This invention belongs to the field of oxygen-enriched combustion technology, specifically relating to an oxygen-enriched combustion circulating flue gas desulfurization system and method. Background Technology

[0002] Oxygen-enriched combustion technology is considered one of the most promising clean combustion technologies. It replaces air with a mixture of oxygen and flue gas in a specific ratio, avoiding the presence of nitrogen in the air and effectively reducing the formation of nitrogen oxides. Simultaneously, the concentration of carbon dioxide in the boiler exhaust gas is significantly increased, facilitating subsequent capture, storage, and utilization to achieve ultra-low carbon dioxide emissions and reduce environmental impact. Increasing the oxygen content in the combustion air allows for more complete fuel combustion. At the same time, it reduces the required combustion air volume and fan energy consumption, and increases the carbon dioxide content in the exhaust gas. However, considering economic factors and supply temperature, oxygen is generally mixed with flue gas in a 3:7 ratio.

[0003] When circulating flue gas is directly fed into the boiler, the sulfur dioxide content inside the furnace increases to 3-4 times that of a normal boiler during operation, exacerbating corrosion of the boiler's heating surfaces and posing a significant threat to the boiler's safe operation. Meanwhile, some of the exhaust gas from oxygen-enriched combustion boilers is treated and then captured and stored by a carbon dioxide collection device. The effectiveness of exhaust gas desulfurization directly affects the concentration of carbon dioxide captured, the adsorption activity and lifespan of the collection material, and can also cause equipment corrosion and other problems.

[0004] Most existing desulfurization systems only perform one desulfurization operation on the flue gas. Although the theoretical desulfurization efficiency can reach 90% or higher, considering factors such as industrial operating conditions, the actual desulfurization efficiency will be lower than expected. As a result, the flue gas after desulfurization still contains a certain concentration of SO2. x This approach cannot solve the aforementioned problems. For example, Chinese patent application CN111151118B discloses a boiler flue gas desulfurization system using a dry desulfurization method with baking soda. This system introduces flue gas into a desulfurization tower, using a fan and a mixer to fully mix and react the baking soda powder injected into the tower with the flue gas to improve desulfurization efficiency. The flue gas is discharged from the desulfurization equipment after one desulfurization, but it still contains a certain concentration of sulfur, which will affect the operation of the oxygen-enriched combustion boiler and the carbon dioxide collection equipment. Summary of the Invention

[0005] The purpose of this invention is to provide an oxygen-enriched combustion circulating flue gas desulfurization system and method, which can achieve efficient desulfurization of flue gas to meet the operational requirements of oxygen-enriched combustion boilers.

[0006] This invention is achieved through the following technical solution:

[0007] An oxygen-enriched combustion circulating flue gas desulfurization system includes a boiler and an air separation device. The boiler outlet is connected to the economizer inlet; the economizer outlet is connected to the first inlet of a gas preheater; the first outlet of the gas preheater is connected to the inlet of a denitrification device, the second outlet is connected to the secondary air inlet of the boiler burner, and the third outlet is connected to the inlet of a coal mill. The coal mill outlet is connected to the coal inlet of the boiler. The outlet of the desulfurization device is connected to the first inlet of a flue gas cooler; the first outlet of the flue gas cooler is connected to the first inlet of a desulfurization chamber, and the second outlet is connected to the inlet of a dust collector. The dust collector outlet is connected to the first inlet of a pressurized adsorption chamber via a first fan. The outlet of the desulfurization chamber is connected to the flue gas cooler... The second inlet is connected to the gas preheater; the first outlet of the pressurized adsorption chamber is connected to the third inlet of the gas preheater and the inlet of the flue gas dryer, respectively, and the second outlet is connected to the second inlet of the vacuum desorption chamber; the first outlet of the vacuum desorption chamber is connected to the second inlet of the pressurized adsorption chamber, and the second outlet is connected to the second inlet of the desulfurization chamber through the second fan; the outlet of the air separator is divided into two paths, one path is connected to the first inlet of the vacuum desorption chamber, and the other path is connected to the inlet of the oxygen injector through a branch path; the first outlet of the oxygen injector is connected to the third inlet of the gas preheater, and the second outlet of the oxygen injector and the first outlet of the flue gas dryer are connected to the second inlet of the gas preheater; the second outlet of the flue gas dryer is connected to the inlet of the carbon dioxide collection device.

[0008] A further improvement of the present invention is that a first valve is provided on the pipeline connecting the outlet of the air separator to the inlet of the oxygen injector via a branch.

[0009] A further improvement of the present invention is that a second valve is provided on the pipeline connecting the second outlet of the vacuum desorption chamber to the second inlet of the desulfurization chamber via the second fan.

[0010] A further improvement of the present invention is that a third valve is provided on the pipeline connecting the first outlet of the pressurized adsorption chamber to the inlet of the flue gas dryer.

[0011] A further improvement of the present invention is that a fourth valve is provided on the pipeline connecting the second outlet of the flue gas dryer to the inlet of the carbon dioxide collection device.

[0012] A further improvement of the present invention is that a fifth valve is provided on the pipeline connecting the second outlet of the oxygen injector to the second inlet of the gas preheater.

[0013] A further improvement of the present invention is that the flue gas at the outlet of the denitrification device enters the flue gas cooler for cooling, and is then sent to the desulfurization chamber for primary desulfurization. The desulfurized flue gas is returned to the flue gas cooler to recover the waste heat of the flue gas, thus completing the primary desulfurization.

[0014] A further improvement of the present invention is that the flue gas after primary desulfurization is pressurized by a fan and sent into a pressurized adsorption chamber. With the help of the control of the indoor resistance valve, the pressure of sulfur dioxide in the flue gas is increased. After the adsorbent adsorbs the sulfur dioxide, it is sent into the vacuum desulfurization chamber. The flue gas is discharged from the pressurized adsorption chamber, thus completing the secondary desulfurization of the flue gas.

[0015] A further improvement of the present invention is that the adsorbent carrying sulfur dioxide releases sulfur dioxide in the vacuum desulfurization chamber, and the sulfur dioxide is blown out using oxygen prepared by an air separation device. The vacuum level in the chamber is maintained by a fan, and the blown-out sulfur dioxide is sent into the desulfurization chamber by the fan for harmless treatment.

[0016] A method for desulfurizing flue gas using an oxygen-enriched combustion cycle, based on the aforementioned oxygen-enriched combustion cycle flue gas desulfurization system, includes the following steps.

[0017] Step 1: The flue gas from the economizer outlet of the oxygen-enriched combustion boiler passes through the gas preheater and then enters the denitrification device to remove nitrogen oxides from the flue gas.

[0018] Step 2: The denitrified flue gas enters the flue gas cooler to exchange heat with the desulfurized low-temperature flue gas. The cooled flue gas enters the desulfurization device to complete one desulfurization. The desulfurized low-temperature flue gas enters the flue gas cooler to recover the waste heat of the flue gas.

[0019] Step 3: After the fly ash impurities are removed by the dust collector, the desulfurized flue gas is pressurized by the first fan and sent into the pressurized adsorption chamber. The residual sulfur dioxide in the flue gas is captured by the adsorbent, completing the secondary desulfurization of the flue gas and further reducing the sulfur content in the flue gas.

[0020] Step 4: The adsorbent carrying sulfur dioxide is sent into the vacuum desorption chamber. The second fan maintains a sufficient vacuum in the chamber, and the desorbed sulfur dioxide is blown out using oxygen prepared by the air separation device. The adsorbent is then regenerated and sent back to the pressurized adsorption chamber to maintain material circulation. Meanwhile, the oxygen carrying sulfur dioxide is sent into the desulfurization device to prevent sulfur dioxide leakage.

[0021] Step 5: The flue gas after secondary desulfurization is divided into two paths, one as primary flue gas and the other as secondary flue gas. The primary flue gas enters the flue gas dryer for dehydration treatment. Part of the treated flue gas is sent to the carbon dioxide collection device to complete the capture of carbon dioxide. The other part is mixed with oxygen in a certain proportion to form primary combustion air and then sent to the gas preheater. The secondary flue gas is directly mixed with oxygen in a certain proportion to form secondary combustion air and then sent to the gas preheater.

[0022] Step 6: The gas preheater recovers the waste heat of the flue gas and heats the primary and secondary combustion air to a suitable temperature. The primary combustion air enters the coal mill for drying and blows out pulverized coal, which is then sent to the boiler burner. The secondary combustion air directly enters the burner to participate in the combustion process in the furnace.

[0023] The present invention has at least the following beneficial technical effects:

[0024] This invention targets oxygen-enriched combustion boilers and employs pressure swing adsorption-desorption (PSA) for secondary desulfurization of boiler flue gas based on primary desulfurization. This further reduces the sulfur dioxide content in the flue gas, and its specific advantages are as follows:

[0025] 1. It reduces the increase of sulfur dioxide caused by circulating flue gas in oxygen-enriched combustion boilers, which can effectively slow down the corrosion of internal equipment in oxygen-enriched combustion boilers, such as the corrosion of water-cooled walls by SO2, and the corrosion of metal equipment by sulfates formed by sulfur and alkali metals at high temperatures, which is conducive to the economical and safe operation of the unit.

[0026] 2. After secondary desulfurization, the sulfur content of the flue gas is reduced, and the acid dew point of the flue gas is also lowered accordingly. This can avoid acid corrosion of subsequent equipment, such as sulfuric acid vapor liquefaction corrosion caused by flue gas cooling in the flue gas dryer, thereby improving the service life of the equipment and reducing costs.

[0027] 3. The impurities in the flue gas are further reduced, which increases the concentration of collected carbon dioxide, facilitating the subsequent resource utilization of carbon dioxide and the safe operation of the collection equipment. Attached Figure Description

[0028] Figure 1 This is a structural block diagram of an oxygen-enriched combustion cycle flue gas desulfurization system according to the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1-Boiler; 2-Economizer; 3-Denitrification device; 4-Flue gas cooler; 5-Desulfurization chamber; 6-Dust collector; 7-First fan; 8-Pressurized adsorption chamber; 9-Vacuum desorption chamber; 10-Air separation device; 11-Flue gas dryer; 12-Carbon dioxide collection device; 13-Oxygen injector; 14-Gas preheater; 15-Coal mill; 16-Second fan; K1-First valve; K2-Second valve; K3-Third valve; K4-Fourth valve; K5-Fifth valve. Detailed Implementation

[0031] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] As attached Figure 1 As shown, the present invention provides an oxygen-enriched combustion circulating flue gas desulfurization system, comprising a boiler 1 and an air separation device 10. The outlet of the boiler 1 is connected to the inlet of the economizer 2; the outlet of the economizer 2 is connected to the first inlet of the gas preheater 14; the first outlet of the gas preheater 14 is connected to the inlet of the denitrification device 3, the second outlet is connected to the secondary air inlet of the boiler 1 burner, and the third outlet is connected to the inlet of the coal mill 15, the outlet of the coal mill 15 is connected to the coal inlet of the boiler 1; the outlet of the desulfurization device 3 is connected to the first inlet of the flue gas cooler 4; the first outlet of the flue gas cooler 4 is connected to the first inlet of the desulfurization chamber 5, the second outlet is connected to the inlet of the dust collector 6, and the outlet of the dust collector 6 is connected to the first inlet of the pressurized adsorption chamber 8 via a first fan 7; the outlet of the desulfurization chamber 5 is connected to the flue gas cooler... The second inlet of the cooler 4 is connected; the first outlet of the pressurized adsorption chamber 8 is connected to the third inlet of the gas preheater 14 and the inlet of the flue gas dryer 11, respectively, and the second outlet is connected to the second inlet of the vacuum desorption chamber 9; the first outlet of the vacuum desorption chamber 9 is connected to the second inlet of the pressurized adsorption chamber 8, and the second outlet is connected to the second inlet of the desulfurization chamber 5 through the second fan 16; the outlet of the air separator 10 is divided into two paths, one path is connected to the first inlet of the vacuum desorption chamber 9, and the other path is connected to the inlet of the oxygen injector 13 through a branch path; the first outlet of the oxygen injector 13 is connected to the third inlet of the gas preheater 14, and the second outlet and the first outlet of the flue gas dryer 11 are connected to the second inlet of the gas preheater 14; the second outlet of the flue gas dryer 11 is connected to the inlet of the carbon dioxide collection device 12.

[0033] The specific implementation of this invention is as follows:

[0034] 1. Primary desulfurization

[0035] The flue gas from the outlet of the denitrification unit 3 enters the flue gas cooler 4 for cooling, and then is sent to the desulfurization chamber for primary desulfurization. The desulfurized flue gas returns to the flue gas cooler 4 to recover the waste heat of the flue gas, completing the primary desulfurization. In particular, the desulfurization chamber can be either wet desulfurization or dry desulfurization, with priority given to the equipment with the highest desulfurization efficiency.

[0036] 2. Secondary desulfurization

[0037] After primary desulfurization, the flue gas is pressurized by a fan and sent into the pressurized adsorption chamber 8. The pressure of sulfur dioxide in the flue gas is increased by the control of the chamber's resistance valve. After the adsorbent adsorbs the sulfur dioxide, it is sent to the vacuum desulfurization chamber 9. The flue gas is then discharged from the pressurized adsorption chamber 9, completing the secondary desulfurization of the flue gas. Specifically, the adsorbent should meet the following requirements: easy adsorption and desorption of sulfur dioxide, easy regeneration, corrosion resistance, high temperature resistance, non-corrosive, stable properties, inexpensive and durable; activated carbon is preferred.

[0038] 3. Residual sulfur treatment

[0039] The adsorbent carrying sulfur dioxide releases sulfur dioxide in the vacuum desulfurization chamber 9. Oxygen prepared by an air separation device blows out the sulfur dioxide. With the cooperation of the fan and valves, the vacuum level in the chamber is maintained. The blown-out sulfur dioxide is sent into the desulfurization chamber 5 by the fan for harmless treatment.

[0040] 4. Carbon dioxide collection

[0041] The flue gas after secondary desulfurization is divided into two streams via pipeline: primary flue gas and secondary flue gas. The primary flue gas enters the flue gas dryer 11 via a branch. The third valve K3 controls the amount of primary flue gas. After drying, part of the flue gas is sent to the carbon dioxide collection device, and the other part is treated and returned to the boiler. The fourth valve K4 controls the amount of carbon dioxide collected.

[0042] 5. Combustion air is supplied to the boiler.

[0043] After the secondary flue gas and residual primary flue gas are thoroughly mixed with oxygen, they are sent to the gas preheater 14 as secondary and primary combustion air, respectively. The heated primary combustion air enters the coal mill for drying and pulverized coal is blown out. Finally, it is sent to the primary combustion air inlet of the burner and enters the boiler. The heated secondary combustion air is directly sent to the secondary combustion air inlet of the burner and enters the boiler for combustion. Specifically, the oxygen in the combustion air is added by the oxygen injector. The fifth valve K5 controls the mixing ratio of primary flue gas and oxygen, preferably selecting a flue gas:oxygen ratio of 7:3. The first valve K1 controls the amount of oxygen sent to the oxygen injector 13 by the air separator to adapt to changes in boiler load. In particular, the mixing point of oxygen and circulating flue gas should be far enough away from the gas preheater 14 to ensure thorough gas mixing.

[0044] The present invention provides a method for desulfurization of flue gas through oxygen-enriched combustion circulation, comprising the following steps:

[0045] Step 1: The flue gas from the economizer 2 outlet of the oxygen-enriched combustion boiler 1 passes through the gas preheater 14 and then enters the denitrification device 3 to remove nitrogen oxides from the flue gas.

[0046] Step 2: The denitrified flue gas enters the flue gas cooler 4 to exchange heat with the desulfurized low-temperature flue gas. The cooled flue gas enters the desulfurization device 3 to complete one desulfurization. The desulfurized low-temperature flue gas enters the flue gas cooler 4 to recover the waste heat of the flue gas.

[0047] Step 3: After the fly ash impurities are removed by the dust collector 6, the desulfurized flue gas is pressurized by the first fan 7 and sent into the pressurized adsorption chamber 8. The residual sulfur dioxide in the flue gas is captured by the adsorbent, completing the secondary desulfurization of the flue gas and further reducing the sulfur content in the flue gas.

[0048] Step 4: The adsorbent carrying sulfur dioxide is sent into the vacuum desorption chamber 9. The second fan 16 and valves work together to maintain a sufficient vacuum in the chamber. The oxygen prepared by the air separation device 10 blows out the desorbed sulfur dioxide. The adsorbent is regenerated and sent back to the pressurized adsorption chamber 8 to maintain material circulation. Meanwhile, the oxygen carrying sulfur dioxide is sent into the desulfurization device 3 to prevent sulfur dioxide leakage.

[0049] Step 5: The flue gas after secondary desulfurization is divided into two paths, one as primary flue gas and the other as secondary flue gas. The primary flue gas enters the flue gas dryer 11 for dehydration treatment. Part of the treated flue gas is sent to the carbon dioxide collection device 12 to complete the capture of carbon dioxide. The other part is mixed with oxygen in a certain proportion to form primary combustion air and then sent to the gas preheater 14. The secondary flue gas is directly mixed with oxygen in a certain proportion to form secondary combustion air and then sent to the gas preheater 14.

[0050] Step 6: The gas preheater 14 recovers the waste heat of the flue gas and heats the primary and secondary combustion air to a suitable temperature. The primary combustion air enters the coal mill 15 to dry and blow out pulverized coal, and then sends it to the burner of the boiler 1. The secondary combustion air directly enters the burner to participate in the combustion process in the furnace.

[0051] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. An oxygen-enriched combustion circulating flue gas desulfurization system, characterized in that, The system includes a boiler (1) and an air separator (10). The outlet of the boiler (1) is connected to the inlet of the economizer (2). The outlet of the economizer (2) is connected to the first inlet of the gas preheater (14). The first outlet of the gas preheater (14) is connected to the inlet of the denitrification device (3), the second outlet is connected to the secondary air inlet of the boiler (1) burner, and the third outlet is connected to the inlet of the coal mill (15). The outlet of the coal mill (15) is connected to the coal inlet of the boiler (1). The outlet of the denitrification device (3) is connected to the first inlet of the flue gas cooler (4). The first outlet of the flue gas cooler (4) is connected to the first inlet of the desulfurization chamber (5), and the second outlet is connected to the inlet of the dust collector (6). The outlet of the dust collector (6) is connected to the first inlet of the pressurized adsorption chamber (8) via a first fan (7). The outlet of the desulfurization chamber (5) is connected to the second inlet of the flue gas cooler (4). The first outlet of the pressurized adsorption chamber (8) is connected to the third inlet of the gas preheater (14) and the inlet of the flue gas dryer (11), respectively, and the second outlet is connected to the second inlet of the vacuum desorption chamber (9); the first outlet of the vacuum desorption chamber (9) is connected to the second inlet of the pressurized adsorption chamber (8), and the second outlet is connected to the second inlet of the desulfurization chamber (5) through the second fan (16); the outlet of the air separator (10) is divided into two paths, one path is connected to the first inlet of the vacuum desorption chamber (9), and the other path is connected to the inlet of the oxygen injector (13) through a branch path; the first outlet of the oxygen injector (13) is connected to the third inlet of the gas preheater (14), and the second outlet is connected to the first outlet of the flue gas dryer (11) and the second inlet of the gas preheater (14); the second outlet of the flue gas dryer (11) is connected to the inlet of the carbon dioxide collection device (12).

2. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 1, characterized in that, A first valve (K1) is installed on the pipeline that connects the outlet of the air separator (10) to the inlet of the oxygen injector (13) via a branch.

3. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 2, characterized in that, A second valve (K2) is installed on the pipeline connecting the second outlet of the vacuum desorption chamber (9) to the second inlet of the desulfurization chamber (5) via the second blower (16).

4. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 3, characterized in that, A third valve (K3) is installed on the pipeline connecting the first outlet of the pressurized adsorption chamber (8) to the inlet of the flue gas dryer (11).

5. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 4, characterized in that, A fourth valve (K4) is installed on the pipeline connecting the second outlet of the flue gas dryer (11) to the inlet of the carbon dioxide collection device (12).

6. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 5, characterized in that, A fifth valve (K5) is installed on the pipeline connecting the second outlet of the oxygen injector (13) and the second inlet of the gas preheater (14).

7. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 1, characterized in that, The flue gas from the outlet of the denitrification device (3) enters the flue gas cooler (4) to cool down, and then is sent to the desulfurization chamber (5) for desulfurization. The desulfurized flue gas returns to the flue gas cooler (4) to recover the waste heat of the flue gas and complete the first desulfurization.

8. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 7, characterized in that, After the first desulfurization, the flue gas is pressurized by a fan and sent into the pressurized adsorption chamber (8). With the help of the indoor resistance valve, the sulfur dioxide pressure in the flue gas is increased. After the adsorbent adsorbs the sulfur dioxide, it is sent into the vacuum desorption chamber (9). The flue gas is discharged from the pressurized adsorption chamber (8), completing the second desulfurization of the flue gas.

9. The oxygen-enriched combustion circulating flue gas desulfurization system according to claim 8, characterized in that, The adsorbent carrying sulfur dioxide releases sulfur dioxide in the vacuum desorption chamber (9). The sulfur dioxide is blown out using oxygen prepared by the air separation device. The vacuum level in the chamber is maintained by the fan. The blown-out sulfur dioxide is sent into the desulfurization chamber (5) by the fan for harmless treatment.

10. A method for desulfurizing flue gas through oxygen-enriched combustion recirculation, characterized in that, This method, based on an oxygen-enriched combustion cycle flue gas desulfurization system according to any one of claims 1-9, includes the following steps: Step 1: The flue gas from the economizer (2) outlet of the oxygen-rich combustion boiler (1) passes through the gas preheater (14) and then enters the denitrification device (3) to remove nitrogen oxides from the flue gas. Step 2: The denitrified flue gas enters the flue gas cooler (4) to exchange heat with the desulfurized low-temperature flue gas. The cooled flue gas enters the desulfurization chamber (5) to complete one desulfurization. The desulfurized low-temperature flue gas enters the flue gas cooler (4) to recover the waste heat of the flue gas. Step 3: After the fly ash impurities are removed by the dust collector (6), the desulfurized flue gas is pressurized by the first fan (7) and sent into the pressurized adsorption chamber (8). The residual sulfur dioxide in the flue gas is captured by the adsorbent, completing the secondary desulfurization of the flue gas and further reducing the sulfur content in the flue gas. Step 4: The adsorbent carrying sulfur dioxide is sent into the vacuum desorption chamber (9). The second fan (16) maintains a sufficient vacuum in the chamber, and the desorbed sulfur dioxide is blown out by the oxygen prepared by the air separation device (10). The adsorbent is regenerated and sent back to the pressurized adsorption chamber (8) to maintain material circulation. Meanwhile, the oxygen carrying sulfur dioxide is sent into the desulfurization chamber (5) to prevent sulfur dioxide leakage. Step 5: The flue gas after secondary desulfurization is divided into two paths, one as primary flue gas and the other as secondary flue gas. The primary flue gas enters the flue gas dryer (11) for dehydration treatment. Part of the treated flue gas is sent to the carbon dioxide collection device (12) to complete the capture of carbon dioxide. The other part is mixed with oxygen in proportion to form primary combustion air and then sent to the gas preheater (14). The secondary flue gas is directly mixed with oxygen in proportion to form secondary combustion air and then sent to the gas preheater (14). Step 6: The gas preheater (14) recovers the waste heat of the flue gas and heats the primary and secondary combustion air to a suitable temperature. The primary combustion air enters the coal mill (15) to dry and blow out coal powder, which is then sent to the burner of the boiler (1). The secondary combustion air directly enters the burner to participate in the combustion process in the furnace.

Images