JPS6143087B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a wet flue gas desulfurization system, and more particularly to a wet flue gas desulfurization system having a cooling tower and an absorption tower, in which uneven flow of gas in the equipment after the cooling tower is improved. The general configuration of a flue gas desulfurization apparatus equipped with a cooling tower and an absorption tower will be explained based on FIG. 1. In the figure, the gas to be treated is introduced into the cooling tower 10 from line 1, where it is brought into contact with the cooling liquid supplied from line 14, and after absorbing some SO ₂ and removing dust, the gas is introduced into duct 2 and It is sent to the absorption tower 20 through the mist eliminator 4 in the duct. Absorption tower 2
At 0, the gas to be treated comes into contact with an absorbing liquid (e.g. lime slurry) supplied from line 24, and the gas in the gas is
After the SO ₂ is removed, it is discharged through line 3. The absorption liquid is sent from the absorption tower circulation tank 40 to the absorption tower 20 via the lines 21 and 24 by the circulation pump 60, and a part is discharged outside the system from the line 23 or is sent to the cooling tower circulation tank 30. Sent. Absorbing liquid flows from the absorption tower 20 to the line 25
It is returned to the absorption tower circulation tank 40 again through the absorption tower circulation tank 40.
In the cooling tower 10, cooling water is passed from the cooling tower circulation tank 30 to the line 11, the cooling tower circulation pump 50,
It is returned to the cooling tower 10 through lines 12 and 14, and a portion is discharged from the system through line 13. On the other hand, the absorbent is replenished from the line 26 to the absorption tower circulation tank 40, and in this absorption tower circulation tank 40, the pH of the absorption liquid is restored by dissolving the absorbent, and the absorbent is absorbed again as described above. Sent to Tower 20. When the dust in the gas to be treated is separated and removed in the cooling tower 10, the cooling liquid containing the removed dust is passed through the cooling tower circulation tank 30 to the cooling tower 10.
At this time, the droplets of the circulating fluid sprayed in the cooling tower 10 or the fine mist generated by mixing and contacting the sprayed circulating fluid with the gas are entrained in the gas flow. scatter. In order to remove the mist containing these dusts, an absorption tower 20
A mist eliminator 4 is installed in the communication section leading to. In order to fully demonstrate the mist removal performance of the mist eliminator 4, it is necessary to rectify the gas to be treated at a gas flow rate suitable for the type of the mist eliminator 4 and flow it into the mist eliminator 4. This is because the mist collecting principle of the mist eliminator 4 utilizes inertial collision, and the collected mist is prevented from being scattered again if the gas flow velocity exceeds a predetermined amount. Conventionally, a rectifier plate (such as a buttful plate) has been inserted into the gas flow path in order to simply rectify the gas flow velocity at the inlet of the mist eliminator 4. In the case of gas containing a large amount of solid matter such as fly ash, the concentration of solid matter in the circulating fluid of the cooling tower increases, and a large amount of solid matter such as fly ash and calcium sulfate adheres to the rectifying plate and inside the duct 2. There is a problem in that draft loss suddenly increases, making continuous operation of the device difficult. This kind of solid matter adhesion inside the duct 2 becomes a problem even when a current plate is not installed, and especially a lot of solid matter adheres to the ceiling and bottom of the duct 2, so in the case of long-term continuous operation, the draft loss may be excessive. It has the disadvantage of becoming The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art, to minimize the uneven flow of gas in the duct when the treated gas cooled in the cooling tower enters the mist eliminator, and to improve the separation efficiency of the mist eliminator. It is an object of the present invention to provide a wet type flue gas desulfurization device that can prevent solid matter from adhering to the inside of a duct. In order to achieve the above object, the present invention provides a duct leading from a cooling tower to a mist eliminator in a shape that reduces adhesion and accumulation of solid matter such as fly ash and draft loss. That is, the present invention allows the gas to be treated to pass through a cooling tower equipped with a cooling liquid spraying means, and introduces the cooled gas from the side of the cooling tower into an absorption tower through a duct having a mist eliminator. In a wet flue gas desulfurization device that absorbs sulfur oxides in the gas by reacting with the absorption liquid in the absorption tower, the inclination angle from the horizontal of the inner wall of the duct from the cooling tower to the mist eliminator is approximately at the ceiling surface. 5 degrees, and approximately 15 degrees at the bottom. Hereinafter, the present invention will be explained in more detail with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing the shape of the duct from the cooling tower to the mist eliminator in the present invention. In order to prevent the adhesion or accumulation of dust in the gas, it is most preferable that the angle A between the ceiling surface of the inner wall of the duct 2 and the horizontal plane be 5 degrees, and the angle B between the bottom surface of the duct inner wall and the horizontal plane be 15 degrees. . The above-mentioned angle may be slightly changed as long as the object of the present invention is achieved, and depending on the conditions, a range of ±3 degrees from the above-mentioned angle may be allowed. In addition to the above-mentioned angle, the cross-sectional area of the flow passage, the length of the flow passage, etc. are involved in dust adhesion, and the duct dimensions that match the above-mentioned angle setting are selected. The basis for selecting the above angle will be explained below based on various experimental examples. In the illustrated desulfurization equipment, the ceiling angle A and the bottom angle B of the duct 2
Table 1 shows the results of measuring the unbalanced flow rate and pressure loss ΔP of the gas in the duct while changing the angle from 5 degrees to 15 degrees, respectively.

[Table] From the above results, although there is some variation, it is clear that the combination of ceiling angle A of 5 degrees and bottom angle B of 15 degrees is the most suitable. In addition, in combinations where the ceiling angle A was 30 to 45 degrees and the bottom angle B was 0 degrees or 60 degrees, the gas drift ratio was 20% or more. Furthermore, for comparison, Table 2 shows the uneven flow rate and pressure loss of the duct 2 when the conventional angles A and B are respectively 0 degrees, A is 45 degrees, and B is 60 degrees.

[Table] Next, FIG. 3 shows an example of the relationship between the pressure loss of the duct and the gas amount when the duct shape of the present invention is used (the amount of circulating fluid in the cooling tower is 7.5 m ³ /hr). In the figure, C represents the embodiment of the present invention in which the ceiling angle A is 5 degrees and the bottom angle B is 15 degrees, and D represents the case in which the angle A is 45 degrees and the angle B is 60 degrees. Comparative examples are shown below. From the results shown in the figure, it is clear that when the duct shape of the present invention is used, the draft loss of the duct is significantly smaller than that of the comparative example. According to the above embodiment, by setting the ceiling angle of the duct from the cooling tower to the mist eliminator to about 5 degrees and the bottom angle to about 15 degrees, the gas unbalance rate can be reduced by about 5% and the draft loss can be reduced at rated load. It can be suppressed to about 10%. It was confirmed that the dust removal performance was hardly affected by the shape of the duct. The above example deals with the case where the lower part of the cooling tower and the absorption tower are connected through a duct. A similar effect can be obtained by making the duct the same shape as in the previous embodiment. As described above, according to the present invention, it is possible to reduce the gas unbalanced flow rate in the duct leading to the eliminator, suppress the pressure loss, and reduce the adhesion and accumulation of dust in the duct.

[Brief explanation of the drawing]

Fig. 1 is a general equipment system diagram of a flue gas desulfurization equipment, Fig. 2 is a sectional view showing the shape of the duct from the cooling tower to the mist eliminator used in the present invention, and Fig. 3 is a diagram showing the implementation of the present invention. FIG. 4 is a diagram showing example results. 1, 3... Line, 2... Duct, 4... Mist eliminator, 30... Cooling tower circulation tank.

Claims (1)

[Claims] 1. The gas to be treated is passed through a cooling tower equipped with a cooling liquid spraying means, and the cooled gas is introduced into the absorption tower from the side of the cooling tower through a duct having a mist eliminator, and the gas is introduced into the absorption tower. In a wet flue gas desulfurization equipment that absorbs and removes sulfur oxides in the gas by reacting with an absorption liquid of Wet type flue gas desulfurization equipment that is characterized by a temperature of approximately 15 degrees.