KR100375566B1 - Semi Dry reacting CYclone BAGfilter(SD-CYBAG) System for eliminating pollutant gas and dust including Mercury and heavy metal - Google Patents

Abstract

The present invention integrates a semi-dry reactor, an activated carbon injection device, a centrifugal dust collector and a bag filter house to simultaneously remove dust and harmful acid gases including heavy metals such as mercury among the pollutants emitted after combustion in incinerators, power plants and other industrial facilities. A simultaneous treatment device for harmful acid gas and particulate contaminants. Hazardous acid gases and dust introduced through the inlet turn over the centrifugal dust collector, react with the slurry of slaked lime (Ca (OH) ₂ ) sprayed from the top of the centrifugal dust collector, and are removed together with the dust through the bottom hopper of the centrifugal dust collector. The particles react with the activated carbon powder injected near the inlet and are removed from the lower centrifugal dust collector. The first filtered harmful acid gas and dust (including mercury and heavy metals) flow into the bag filter house above the centrifugal dust collector, It is completely filtered and discharged through re-reaction by some accumulated slaked lime and activated carbon.

The present invention can greatly reduce the installation area and manufacturing cost by unifying the existing post-treatment equipment consisting of a semi-dry scrubber (SDR), an activated carbon injection device (AC Feeder), a centrifugal dust collector (Cyclone), a bag filter house (Bag Filter House). . In addition, since it is integrated, there is no need for a separate insulation treatment for maintaining the reaction temperature outside the semi-dry reactor, and it can reduce power consumption due to reheating in the bag filtering process. Simultaneous processing in the system shortens the transportation route and significantly reduces the driving power ratio. In addition, the dust collecting efficiency is increased due to the increase in the particle size of the dust particles due to the aggregation of the dust particles and water, and most of the dust is collected in the lower cyclone, thereby reducing the burden of the upper dust collecting filter and extending the filter life.

Description

Semi-dry reacting CYclone BAGfilter (SD-CYBAG) System for eliminating pollutant gas and dust including Mercury and heavy metal}

The present invention is an integrated type to remove harmful acid gases such as HCl, SO ₂ , HF, H ₂ S and particulate pollutants such as mercury, heavy metals and dust among the pollutants contained in combustion exhaust gas of incinerator or industrial boiler. The centrifugal reaction filtration apparatus, and more specifically, as shown in [Fig. 3], the centrifugal dust collector 18, the slaked lime slurry injection nozzle 11, and the activated carbon injector 15, which use centrifugal force, are located in the lower part, and the bag filter in the upper part. House 14 and pulse jet dust removal device 20 is located. When the pulse jet dust removal device 20 stacks particulate contaminants such as dust on the bag filter and the pressure difference between the inside and the outside of the bag filter is 1000 Pa or more, the bag filter is instantaneously (0.1 sec) back-filtered with a high-pressure (5 atm) air jet. By automatically spraying on the stacked contaminants, there is no need to stop the operation of the device designed for exhaustion of the bag filter. Therefore, the present invention relates to a centrifugal dust collector, a semi-dry reactor, an activated carbon injector, a bag filter, and a pulse jet dedusting device 20 by integrating exhaust gas and dust simultaneously.

In general, fly ash and volatile organic gases (VOC), including acidic gases (HCL, SO ₂ , HF, H ₂ S) and nitrogen oxides (NO, NO ₂ ) during combustion in incinerators, power plants and other industrial facilities. ) Is contained in the exhaust gas. Among these harmful substances, various methods for removing acid gases such as hydrogen chloride (HCl), sulfur oxide (SO ₂ ) and hydrogen sulfide (H ₂ S) and other harmful substances have been proposed. Among them, a semi-dry reactor (3) is used. The process is a method of removing harmful substances by spraying limestone of fine particles on the exhaust gas, and especially after treatment, wastewater does not occur, and it is mainly used recently for high efficiency treatment of hazardous substances. Acid gas is removed through the semi-dry reactor, and the dry product generated in this process, and particulate matter such as fly ash and heavy metal are collected by separately installed centrifugal dust collector and bag filter.

In FIG. 1, in the conventional incinerator exhaust gas treatment apparatus, harmful acid gas discharged from the incinerator 1 is supplied to the centrifugal dust collector 2 through an inlet pipe to remove particulate matter having a large particle size. The exhaust gas passing through the centrifugal dust collector is introduced into the semi-dry reactor 3 and reacts with the slaked lime slurry 9 injected from the nozzle. In this process, the acid gases are converted into dry products and discharged through the lower hopper, and the exhaust gas leaves the semi-dry reactor containing fine dust and unreacted materials and enters the baghouse 5 for final filtration.

In general, the reactant of the injected slaked lime slurry and the noxious acid gas of the semi-dry reactor is not sufficiently dried and accumulates on the inner wall of the semi-dry reactor. Therefore, in the conventional exhaust gas treatment apparatus, there is a problem in that the apparatus needs to be periodically decomposed by disassembling the apparatus. In addition, the temperature of the inlet gas of the semi-dry reactor where the reaction between the harmful acid gas and the lime lime slurry is about 250 degrees Celsius, which is discharged after passing through the bag filter due to the latent heat of evaporation of liquid slurry and the loss of heat to the outside of the apparatus. The temperature of the gas is lowered to 150 degrees Celsius. In the removal of harmful acid gas through liquid slaked lime, the lower the outlet gas temperature, ie, the greater the contact and reaction amount of slaked slurry with the harmful acid gas, the higher the removal efficiency. However, if the temperature is too low, the temperature of the exhaust gas passing through the bag filter is too low. As the moisture is condensed and the microfiltration of the bag filter becomes clogged, the thermal insulation of the device is prevented to prevent heat loss to the outside, and the temperature of the gas flowing into the semi-dry reactor is higher than the proper reaction temperature. .

Accordingly, the present invention has been made to solve the above problems of the prior art, the centrifugal precipitator 18 is located at the lower end as shown in [Fig. 3], so that the centrifugal precipitator can also serve as a semi-dry reactor at the same time With the injection nozzle 11 and the bag filter house 14 located at the top, one conventional multi-stage process shown in FIG. 1 for treating noxious gases and particulate matter is shown in FIG. Integrates into the process to save installation and operating costs, prevents the reaction deposits of harmful acid gas and slaked lime accumulated on the inner wall of semi-dry reactors, and increases the efficiency of harmful acid gas treatment and dust collection at the same time. The purpose is.

1 is a block diagram of a conventional exhaust gas treatment system

2 is a block diagram of an exhaust gas treating apparatus according to the present invention

3 is a longitudinal cross-sectional view of the exhaust gas treating apparatus according to the present invention.

* Explanation of symbols for the main parts of the drawings

1: Source of harmful acid gas and particulate pollutant

2: centrifugal dust collector (cyclone)

3: semi-dry reactor

4: activated carbon injector

5: bag filter house

6: blower

7: stack

8: compressed air storage tank

9: slaked lime slurry storage tank

10: integrated centrifugal filtration device

11: Slaked lime slurry nozzle

12: Bagfilter

13: exit

14: upper bag filter house

15: activated carbon injection device

16: entrance

17: Rotary valve

18: bottom centrifugal dust collector

19: inner cylinder 20: pulse jet dust removal device

In the present invention for achieving the above object, in the apparatus for treating the exhaust gas discharged from the incinerator, etc., as shown in [Fig. 3], the slaked lime slurry nozzle for the semi-dry reactor centrifugal dust collector type at the bottom It is located, the activated carbon injector 15 is installed so that the adsorption and removal of mercury and heavy metals, it is characterized in that the bag filter house 14 and the pulse jet dust removal device 20 is located at the top.

As shown in [Fig. 3], the inlet 16 into which the exhaust gas from the contaminant discharge source 1, such as an incinerator, flows in at the lower end is tangentially positioned at the top of the centrifugal dust collector type semi-dry reactor, and the circumference is at the top of the semi-dry reactor. A plurality of slaked lime slurry injection nozzles 11 are positioned in the direction. The high-speed harmful acid gas introduced through the inlet forms a swirling flow and collects particulate contaminants by centrifugal force and reacts with the slaked lime slurry injected from the nozzle 11 on the top of the semi-dry reactor to remove acidic gases. . The dry product generated at this time is collected through the rotary valve 17 installed in the lower hopper together with the particulate contaminants, and in this process, the dust collection efficiency is increased due to the aggregation of moisture and particulate contaminants. In addition, the activated carbon injector 15 is installed near the inlet to adsorb and remove mercury and heavy metals from the inlet pipe 16 and to be collected by the lower rotary valve 17. The secondary adsorption reaction is performed on the surface of the filter 12.

The strong swirl flow caused by the high-speed harmful acid gas introduced increases the intensity of turbulence and residence time, thereby increasing the reactivity of polluting gas with liquid slaked lime, and increasing the adsorption of heavy metals such as mercury and activated carbon. In addition, the abrasion effect of the strong swirl flow prevents the products that accumulate and adhere to the semi-dry reactor inner wall surface in advance. Most of the toxic acid gases and heavy metals reacted with the slaked lime slurry and activated carbon in the swirl flow are removed from the centrifugal reactor, and after moving to the lower cone part, they form a rising vortex in the center of the centrifugal dust collector-type semi-dry reactor and follow the inner cylinder part 19. It is moved to the upper bag filter house 14 and secondary filtered through the bag filter 12. At this time, the cross-sectional shape of the inlet 16 and the installation position and dimensions affect the dust collection efficiency and the degree of pressure loss.

The inner cylinder 19 which connects the upper and lower portions has a range so as to simultaneously generate an optimal ascent air and a descending airflow according to the diameter A, the length P, and the inclination angle G between the outer cylinder as shown in [Fig. 4]. Restrict Unlike general standard cyclones, the inner cylinder 19 structure of the present invention is very sensitive to the dust collection performance, and sets the optimum range through computational fluid dynamics (CFD) simulation. Hazardous acid gases and dust introduced into the inlet (16) are centrifuged in the lower cyclone through high-speed turning, and some dust is collected through the rotary valve (17) of the lower hopper, and the remaining fine dust (usually 10 microns or less 30- 60%) is ascending to the upper bag filter house while turning on the wall of the inner cylinder (19). The dust that has risen to the upper part through the inner cylinder is collected in the bag filter 12 while continuously turning, and some dust is collected by descending to the lower end through the center of the inner cylinder part 19 along the air flow descending from the center again. . This phenomenon is due to the continuity of the vortex. In the standard cyclone, the swirl flow rises and disappears along the inner cylinder, but in the design of the device, the swirl vortex is reflected from the upper baghouse upper surface and rides through the central airflow to the lower cyclone. It appears because you can continue to descend. In particular, the dust cake dedusted from the surface of the filter cloth is also collected by descending to the lower cyclone portion by the downdraft so as to prevent reattachment, scattering phenomenon, etc. of dust during dedusting. Important factors in the design of the inner cylinder portion 19 of the apparatus are the diameter, length, angle of inclination of the inner cylinder, and the like. Inlet aspect ratio: B = 2C, Hopper height E: 0.83D <E, inner diameter and inlet height ratio B = 0.22D, the optimum range for the inner cylinder dimension connecting the upper baghouse is the inner diameter A: 0.55D <A <0.65D, the lower end position of the length P: P end = inlet center (B / 2), the angle of inclination between the inner and outer cylinders G = 45 degrees, the most optimal effect is achieved.

Among the dust and dry products passed through the lower centrifugal type semi-dry reactor, the fine dust and the dry product which are not collected in the lower hopper are filtered in the bag filter 12, whereby the fine dry product collected on the surface of the bag filter is fixed. A collecting dust layer of thickness is formed. In the collected dust layer, unreacted dry slaked lime injected from a centrifugal dust type semi-dry reactor is further reacted with harmful substances, thereby simultaneously removing particulate fine pollutants and trace gaseous pollutants. The contaminants collected in the bag filter by secondary filtration are collected and collected along the descending air flow in the rising vortex formed from the baghouse to the bottom hopper of the centrifugal dust collector type through the jet jet of compressed air.

According to the present invention made as described above, by integrating the centrifugal dust collector, semi-dry reactor, activated carbon injector and bag filter, the installation area of the incineration plant can be reduced, and a separate insulation device and a reheater device are installed outside each device and the piping pipe. The need for installation and operation can reduce energy consumption and prevent sedimentation of slaked lime reactants that accumulate on the inside walls of the device. In addition, the temperature in the bag filter house can be properly adjusted even if the temperature of the inlet gas into the centrifugal dust collector-type semi-dry reactor is lowered, thereby preventing the condensation of moisture in the bag filter while improving the efficiency of removing the acid gas and at the same time. Can remove heavy metals. By speeding up the exhaust gas flowing into the device, it is possible to simultaneously increase the removal efficiency of dust and harmful acid gases and at the same time make the device compact.

Claims (2)

A device for simultaneously treating harmful acid gas and dust discharged from an incinerator and a combustion device, comprising: spraying an absorbent such as an inlet 16 of the present device and a slaked lime slurry connected to a gas outlet of the incinerator and a combustion device on one side; A centrifugal precipitator-type semi-dry reactor equipped with a nozzle 11 and an injector 15 for injecting activated carbon, and an integrated exhaust gas composed of a bag filter house 14 and a pulse jet dedusting device 20 of which the other side is circular or square. Processing unit. The inlet of the inlet flowing into the centrifugal dust collector-type semi-dry reactor in the lower part has a rectangular shape and has an inlet portion as shown in [Fig. 4]. Ratio: B = 2C, Hopper height E: 0.83D <E, Inner cylinder diameter and inlet height ratio: B = 0.22D, the optimum range for the inner cylinder dimension connecting the upper baghouse is Inner diameter A: 0.55 D <A <0.65D, lower end position of inner cylinder length P: P end = inlet center (B / 2), integral exhaust gas treatment device composed of inclination angle G = 45 degrees between inner and outer cylinders.