A method for collaborative ultra-clean emission of flue gas from an industrial boiler through a two-stage circulating fluidized bed

Abstract

The present invention relates to a method for the collaborative ultra-clean emission of flue gas from an industrial boiler by means of a two-stage circulating fluidized bed. The present invention adopts a technical method in which an alkaline neutralizing agent adding device, a SO2 circulating fluidized bed removal device, a separator of the SO2 circulating fluidized bed removal device, a NOx low-temperature catalytic oxidant adding device, a NOx circulating fluidized bed oxidation device, a separator of the NOx circulating fluidized bed removal device, a return pipeline, an NH3 injection device, and a particulate matter removal and deep purification device are sequentially arranged along the flue gas flow direction. The present invention realizes the efficient removal and ultra-clean emission of constant pollutants such as SO2, NOx, and dust in the flue gas, as well as ultrafine pollutants such as particulate matter below PM2.5 and aerosols. The flue gas purification effect is good, and the pollutant removal efficiency is high. By adopting the removal method of the present invention, the removal rates of constant pollutants such as SO2, NOx, and dust are ≥99.9%; the capture rates of ultrafine pollutants such as particulate matter below PM2.5 and aerosols are ≥99.99%.

Description

Technical Field

[0001] The present invention relates to a method for synergistic ultra-clean emission of industrial boiler flue gas through a two-stage circulating fluidized bed, and particularly to a method for synergistic ultra-clean emission of industrial boiler flue gas composed of an alkaline neutralizing agent adding device, a SO2 circulating fluidized bed removal device, a separator of the SO2 circulating fluidized bed removal device, a NOx low-temperature catalytic oxidant adding device, a NOx circulating fluidized bed oxidation device, a separator of the NOx circulating fluidized bed oxidation device, a return pipe, an NH3 injection device, and a particulate removal and deep purification device. Background Art

[0002] Industrial boiler flue gas emissions have the remarkable characteristics of diverse boiler types, variable boiler operating conditions, and complex flue gas components, which bring difficulties to the treatment and stable operation of ultra-clean flue gas emissions. Moreover, due to large differences in different regions, the funds for industrial boiler flue gas emissions are often relatively limited. This requires seeking a flue gas ultra-clean emission technology with simple process, relatively low investment, strong load adaptability, stable operation, and low operating cost. Currently, the pollutant purification processes for industrial boiler flue gas often have large investment, poor operation stability, high operating cost, and weak load adaptability, and usually cannot meet the user's requirements and achieve efficient removal and ultra-clean emission of flue gas pollutants.

[0003] The present invention adopts a two-stage circulating fluidized bed high-efficiency synergistic removal process for industrial boiler flue gas, and realizes the ultra-clean emission of industrial boiler flue gas pollutants through the efficient removal of constant pollutants such as SO2, NOx, and dust, as well as ultrafine pollutants such as particulate matter below PM2.5 and aerosols. The present invention adopts a synergistic removal innovation technology based on principles such as gas-solid neutralization reaction, gas-solid catalytic oxidation, and particle filtration and adsorption removal, and designs a method for synergistic ultra-clean emission of industrial boiler flue gas. Through engineering practice verification, the expected results have been achieved. Summary of the Invention

[0004] The object of the present invention is to provide a method for the collaborative ultra-clean emission of industrial boiler flue gas in a two-stage circulating fluidized bed, which adopts an industrial boiler flue gas two-stage circulating fluidized bed collaborative ultra-clean emission method with an alkaline neutralizing agent adding device, a SO2 circulating fluidized bed removal device, a SO2 circulating fluidized bed removal device separator, a NOx low-temperature catalytic oxidant adding device, a NOx circulating fluidized bed oxidation device, a NOx circulating fluidized bed removal device separator, an NH3 injection device, and a particulate matter removal and deep purification device arranged in sequence along the flue gas flow direction. The present invention realizes the ultra-clean emission of industrial boiler flue gas pollutants through the efficient removal of constant pollutants such as SO2, NOx, and dust, as well as ultrafine pollutants such as particulate matter below PM2.5 and aerosols. The present invention adopts a collaborative removal innovation technology based on principles such as gas-solid neutralization reaction, gas-solid catalytic oxidation, and particle filtration and adsorption removal, and designs a method for the collaborative ultra-clean emission of industrial boiler flue gas in a two-stage circulating fluidized bed. Through engineering practice verification, the expected effect has been achieved. The present invention is convenient for operation, maintenance, and overhaul, has a low operation cost, and is applicable to the simultaneous efficient removal and ultra-clean emission of acidic gases and aerosol pollutants in the flue gas of complex furnace types such as W-shaped flame furnaces.

[0005] To achieve the above object, the present invention sets an alkaline neutralizing agent adding device in the inlet flue. The alkaline neutralizing agent adding device sprays an alkaline neutralizing agent into the inlet flue, and the alkaline neutralizing agent is fully mixed with the fly ash in the flue gas and adheres to the surface of the fly ash.

[0006] To achieve the above object, the present invention sets a SO2 circulating fluidized bed removal device. After the fly ash in the flue gas adheres to the alkaline neutralizing agent, it enters the SO2 circulating fluidized bed removal device at high speed and turbulently. The SO2 in the flue gas reacts with the alkaline neutralizing agent in a neutralization reaction. The fly ash adhering to the alkaline neutralizing agent in the flue gas returns to the SO2 circulating fluidized bed removal device again through the SO2 circulating fluidized bed removal device separator under the carrying of the high-speed gas flow. The unreacted alkaline neutralizing agent can further react with the SO2 in the flue gas, greatly improving the utilization efficiency of the alkaline removal agent and saving the operation cost.

[0007] To achieve the above object, the present invention sets a NOx low-temperature catalytic oxidant adding device on the connecting flue between the circulating fluidized beds. The low-temperature catalytic oxidant adding device sprays a NOx low-temperature catalytic oxidant into the connecting flue between the circulating fluidized beds, and the NOx low-temperature catalytic oxidant can react with the NOx in the flue gas in a low-temperature catalytic oxidation reaction.

[0008] To achieve the above object, the present invention provides a NOx circulating fluidized bed oxidation device, which is connected to a SO2 circulating fluidized bed removal device through a connecting flue between the circulating fluidized beds. The flue gas after removing SO2 passes through the connecting flue between the circulating fluidized beds, and enters the NOx circulating fluidized bed oxidation device after adding a NOx low-temperature catalytic oxidant. In the NOx circulating fluidized bed oxidation device, the NOx pollutants in the flue gas are catalytically oxidized to NO2 which is easy to remove under the action of the low-temperature catalytic oxidant. The particulate matter in the flue gas is carried by the high-speed air flow and returns to the NOx circulating fluidized bed oxidation device again through the separator of the NOx circulating fluidized bed oxidation device, so that the NOx low-temperature catalytic oxidant can be fully recycled, the catalytic oxidation efficiency of the low-temperature catalytic oxidant is improved, the utilization efficiency of the NOx low-temperature catalytic oxidant is greatly improved, and the operation cost is saved.

[0009] To achieve the above object, the present invention provides a return pipe at the lower part of the NOx circulating fluidized bed oxidation device. Part of the large particles in the flue gas return to the inlet flue again through the return pipe, so that the alkaline neutralizer and the NOx low-temperature catalytic oxidant can be fully recycled, the utilization efficiency is improved, and the operation cost is saved.

[0010] To achieve the above object, the present invention provides an NH3 injection device on the connecting flue after the circulating fluidized bed. The NH3 injected into the flue gas can react with NO2 in the flue gas under the action of the NOx low-temperature catalytic oxidant, and the NO2 in the flue gas is finally completely harmlessly treated to achieve the ultra-clean emission of NOx.

[0011] To achieve the above object, the present invention provides a particulate matter removal and deep purification device. The flue gas discharged from the NOx circulating fluidized bed oxidation device enters the particulate matter removal and deep purification device through the connecting flue after the circulating fluidized bed. The particulate matter removal and deep purification device adopts a bag filter process. The NOx low-temperature catalytic oxidant in the flue gas is adsorbed on the surface of the bag fiber, which can catalyze the harmless reaction of NH3 and NO2. At the same time, the large particle dust and ultrafine particles in the flue gas are adsorbed and removed by the bag fiber.

[0012] After the constant pollutants such as SO2, NOx, and dust in the flue gas and the ultrafine pollutants such as particulate matter below PM2.5 and aerosol are efficiently purified, they reach the ultra-clean emission standard, and the clean flue gas is discharged through the outlet flue.

[0013] Compared with the prior art, the present invention has the following characteristics:

[0014] (1) The present invention realizes the efficient removal and ultra-clean emission of constant pollutants such as SO2, NOx, and dust in the flue gas and ultrafine pollutants such as particulate matter below PM2.5 and aerosol. The flue gas purification effect is good, and the pollutant removal efficiency is high.

[0015] (2)Using the removal method of the present invention, the removal rates of constant pollutants such as SO2, NOx, and dust are ≥99.9%; the capture rates of ultrafine pollutants such as particulate matter below PM2.5 and aerosols are ≥99.99%.

[0016] (3)The present invention is convenient for operation, maintenance and repair, has low operation cost, and is applicable to the efficient removal and ultra-clean emission of constant pollutants such as SO2, NOx, and dust, as well as ultrafine pollutants such as particulate matter below PM2.5 and aerosols in the flue gas of industrial boilers of various furnace types. Brief Description of the Drawings

[0017] The present invention will be further described in detail below with reference to the drawings.

[0018] Figure 1 It is a schematic process flow diagram of the present invention patent.

[0019] In the figure: 1. Inlet flue, 2. Alkaline neutralizer addition device, 3. SO2 circulating fluidized bed removal device, 4. Separator of SO2 circulating fluidized bed removal device, 5. Connecting flue between circulating fluidized beds, 6. NOx low-temperature catalytic oxidant addition device, 7. NOx circulating fluidized bed oxidation device, 8. Separator of NOx circulating fluidized bed oxidation device, 9. Return pipe, 10. Connecting flue after circulating fluidized bed, 11. NH3 injection device, 12. Particulate matter removal and deep purification device, 13. Outlet flue. Detailed Embodiments

[0020] In Figure 1 along the flue gas flow direction, an alkaline neutralizer addition device, an SO2 circulating fluidized bed removal device, a separator of the SO2 circulating fluidized bed removal device, a NOx low-temperature catalytic oxidant addition device, a NOx circulating fluidized bed oxidation device, a separator of the NOx circulating fluidized bed oxidation device, an NH3 injection device, and a particulate matter removal and deep purification device are sequentially arranged.

[0021] When the method for collaborative ultra-clean emission of flue gas from an industrial boiler with a two-stage circulating fluidized bed of the present invention is in the working state, the alkaline neutralizer addition device arranged in the inlet flue of the present invention sprays an alkaline neutralizer into the inlet flue. The alkaline neutralizer is fully mixed with fly ash in the flue gas and adheres to the surface of the fly ash. The fly ash in the flue gas adhering to the alkaline neutralizer enters the SO2 circulating fluidized bed removal device at high speed and turbulently. The SO2 in the flue gas reacts with the alkaline neutralizer in a neutralization reaction. The fly ash adhering to the alkaline neutralizer in the flue gas returns to the SO2 circulating fluidized bed removal device again through the separator of the SO2 circulating fluidized bed removal device under the entrainment of the high-speed gas flow. The unreacted alkaline neutralizer and the SO2 in the flue gas can further undergo a neutralization reaction.

[0022] The NOx low-temperature catalytic oxidant adding device provided on the connecting flue between the circulating fluidized beds of the present invention sprays the NOx low-temperature catalytic oxidant into the connecting flue between the circulating fluidized beds, and the NOx low-temperature catalytic oxidant can undergo a low-temperature catalytic oxidation reaction with the NOx in the flue gas. The flue gas after SO2 removal passes through the connecting flue between the circulating fluidized beds and enters the NOx circulating fluidized bed oxidation device after the addition of the NOx low-temperature catalytic oxidant. In the NOx circulating fluidized bed oxidation device, the NOx pollutants in the flue gas are catalytically oxidized to NO2 which is easy to remove under the action of the low-temperature catalytic oxidant. The particulate matter in the flue gas is carried by the high-speed gas flow and returns to the NOx circulating fluidized bed oxidation device again through the separator of the NOx circulating fluidized bed oxidation device, enabling the full recycling of the NOx low-temperature catalytic oxidant.

[0023] The NH3 spraying device provided on the connecting flue after the circulating fluidized bed of the present invention sprays NH3 into the flue gas. The flue gas discharged from the NOx circulating fluidized bed oxidation device enters the particulate matter removal and deep purification device through the connecting flue after the circulating fluidized bed. The particulate matter removal and deep purification device adopts a bag-type filtration process. The NOx low-temperature catalytic oxidant in the flue gas is adsorbed on the surface of the bag-type fiber, thereby catalyzing the harmless reaction of NH3 and NO2. At the same time, the large particulate dust and ultrafine particles in the flue gas are adsorbed and removed by the bag-type fiber.

[0024] The constant pollutants such as SO2, NOx, and dust in the flue gas, as well as the ultrafine pollutants such as particulate matter below PM2.5 and aerosol, are highly purified to meet the ultra-clean emission standards, and the clean flue gas is discharged through the outlet flue.

[0025] The above is only the specific implementation manner of the present invention. The technical features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention shall be included in the patent scope of the present invention.

Claims

1. A method for the collaborative ultra-low emission of industrial boiler flue gas in a two-stage circulating fluidized bed, wherein the device for the collaborative ultra-low emission of industrial boiler flue gas in a two-stage circulating fluidized bed mainly consists of an alkaline neutralizer adding device, a SO2 circulating fluidized bed removal device, a separator of the SO2 circulating fluidized bed removal device, a NOx low-temperature catalytic oxidant adding device, a NOx circulating fluidized bed oxidation device, a separator of the NOx circulating fluidized bed oxidation device, a return pipe, an NH3 injection device, and a particulate matter removal and deep purification device, and is characterized in that: An alkaline neutralizer adding device is arranged in the inlet flue, a NOx low-temperature catalytic oxidant adding device is arranged in the connecting flue between the circulating fluidized beds, an NH3 injecting device is arranged in the connecting flue behind the circulating fluidized beds, and a SO2 circulating fluidized bed removal device, a separator of the SO2 circulating fluidized bed removal device, a NOx circulating fluidized bed oxidation device, a separator of the NOx circulating fluidized bed oxidation device, and a particulate matter removal and deep purification device are successively arranged in the outlet flue along the flue gas flow direction.

2. A method for synergistic ultra-clean emission of industrial boiler flue gas in a two-stage circulating fluidized bed, according to claim 1, characterized in that: The NOx circulating fluidized bed oxidation device is respectively connected with the SO2 circulating fluidized bed removal device and the particulate matter removal and deep purification device.

3. A method for the collaborative ultra-clean emission of industrial boiler flue gas in a two-stage circulating fluidized bed, according to claim 1, characterized in that: The return pipes are respectively connected with the NOx circulating fluidized bed oxidation device and the inlet flue.

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