JP3829976B2 - Wet flue gas desulfurization equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a wet flue gas desulfurization apparatus, and in particular, wet flue gas desulfurization suitable for preventing solid oxide accumulation at an outlet portion of an absorption tower that reduces sulfur oxide (hereinafter referred to as SOx) and dust in exhaust gas. Relates to the device.
[0002]
[Prior art]
The system of the conventional wet flue gas desulfurization apparatus is shown in FIG. 3 and FIG. Exhaust gas 1 from a boiler or the like (not shown) is introduced into the absorption tower 4 through the inlet flue 3 and is sprayed from the spray nozzle 11 installed in the spray stage 8 through the spray stage 8 installed in the absorption tower 4. By contacting with the droplets of the absorbent, SOx in the exhaust gas 1 is absorbed on the surface of the absorbent droplets together with soot dust in the exhaust gas 1 and acidic gases such as hydrogen chloride (HCl) and hydrogen fluoride (HF). . A part of the mist 60 containing the solid substance accompanying the gas falls to the bottom surface of the absorption tower outlet 50 and returns to the absorption tower 4, and the mist 60 containing the remaining solid substance is removed by the mist eliminator 5. It is returned to the absorption tower 4 via the mist eliminator drain pipe 61. The clean exhaust gas 2 that has exited the mist eliminator 5 passes through the outlet flue 6 and is reheated as necessary to be discharged from a chimney (not shown). In addition, the SOx concentration in the exhaust gas at the inlet 4 of the absorption tower 4 at this time is measured by the inlet SOx meter 41, and the SOx concentration in the exhaust gas at the outlet of the absorption tower is measured by the outlet SOx meter 42 provided in the outlet flue 6, The desulfurization rate is calculated from these measurement results.
[0003]
Limestone, which is an SOx absorbent, is supplied as a limestone slurry from a limestone slurry tank 15 to a liquid reservoir in the absorption tower 4 by a limestone slurry pump 17. The limestone slurry supply amount at this time is adjusted by the limestone slurry flow rate control valve 18 in accordance with the SOx absorption amount. The absorption liquid is pressurized by the absorption tower circulation pump 7 and supplied to the spray stage 8 in the absorption tower 4. The SOx removed in the absorption tower 4 reacts with calcium in the absorption liquid to become calcium sulfite (including calcium bisulfite) as an intermediate product, and the oxidizing air introduced into the liquid reservoir in the absorption tower 4 As a result, it is oxidized to gypsum to form a final product (gypsum). By supplying air directly into the absorption tower 4 in this manner, the entire reaction is promoted by simultaneously progressing the SOx absorption reaction in the exhaust gas and the oxidation reaction of the generated calcium sulfite, and the desulfurization performance is improved. At that time, the oxidizing air supplied to the absorption tower 4 is refined by the oxidizing stirrer 26 to increase the utilization rate of the oxidizing air.
[0004]
Thereafter, the absorption liquid slurry in the liquid storage section of the absorption tower 4 is extracted according to the amount of gypsum produced by the extraction pump 9, but a part thereof is sent to the pH meter tank 30 and installed in the pH meter tank 30. A pH meter 31 measures the pH of the absorbing solution. The other absorbing liquid is sent to the gypsum dewatering equipment 10 and collected as powder gypsum.
[0005]
On the other hand, the water 12 separated by the gypsum dewatering facility 10 is stored in the filtrate tank 19 and sent to the limestone slurry tank 15 and the like by the filtrate pump 20 and reused as the makeup water 13 in the system. In order to prevent such concentration, the waste water 14 is extracted and sent to the waste water treatment facility 16. In order to keep the liquid level constant, the filtrate tank 19 is supplied with make-up water by the adjusting valve 64.
[0006]
In the wastewater treatment facility 16, chemical treatment by adding chemicals or passing an ion-adsorbing resin or the like and biological treatment with fungi are performed so that each component contained in the wastewater 14 is less than the wastewater standard value. It is performed and the removal processing of the harmful substance in the waste water is performed.
[0007]
In the above prior art, the absorption tower outlet 50 is provided with an upward slope along the absorption tower outlet gas flow 51 as shown in FIG.
[0008]
[Problems to be solved by the invention]
In the above prior art, as shown in FIG. 4, the absorption tower outlet 50 is provided with an upward slope along the absorption tower outlet gas flow 51, and contains solids that have fallen on the bottom surface of the absorption tower outlet 50. When the mist 60 becomes the absorption tower outlet drain 52 and returns to the absorption tower 4, the absorption tower outlet gas flow 51 and the absorption tower outlet drain flow 53 are reversed, so that solids are deposited on the bottom surface of the absorption tower outlet 50. Is prone to occur. In order to prevent the accumulation of solid matter on the bottom surface of the absorption tower outlet 50, it is necessary to increase the inclination angle of the bottom surface. However, there is a problem that the height of the absorption tower 4 is increased. .
[0009]
An object of the present invention is to prevent the accumulation of fixed matter at the absorption tower outlet without increasing the tower height of the absorption tower.
[0010]
[Means for Solving the Problems]
The above-described problem of the present invention includes an absorption tower that absorbs and removes dust and sulfur oxides contained in combustion exhaust gas discharged from a combustion apparatus including a boiler with an absorbent liquid made of an absorbent slurry containing limestone or lime. In the wet flue gas desulfurization device, the ceiling surface of the absorption tower outlet is a horizontal surface, and the wet flue gas desulfurization device is provided with an inclined portion that is inclined downward in the same direction as the gas flow from the bottom end of the absorption tower outlet. Solved.
[0011]
[Action]
By providing a downwardly inclined portion along the absorption tower outlet gas flow at the bottom of the absorption tower outlet, when the mist containing the solids falling on the bottom becomes an absorption tower outlet drain and returns to the absorption tower Since the absorption tower outlet gas flow and the absorption tower outlet drain flow are in the same direction, the absorption tower outlet drain easily flows, and solids are less likely to deposit on the bottom surface of the absorption tower outlet. In addition, since the inclined portion of the bottom surface of the absorption tower outlet is directed downward along the gas flow at the absorption tower outlet, the tower height of the absorption tower does not increase.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
The structure of the absorption tower outlet 50 of the wet flue gas desulfurization apparatus according to the present invention is shown in FIG. The configuration shown in FIG. 1 is applied to the absorption tower portion of the system of the conventional wet flue gas desulfurization apparatus described in FIG.
[0013]
Exhaust gas 1 from a boiler or the like (not shown) is introduced into the absorption tower 4 through the inlet flue 3 and is sprayed from the spray nozzle 11 installed in the spray stage 8 through the spray stage 8 installed in the absorption tower 4. By contacting with the droplets of the absorbent, SOx in the exhaust gas 1 is absorbed on the surface of the absorbent droplets together with soot dust in the exhaust gas 1 and acidic gases such as hydrogen chloride (HCl) and hydrogen fluoride (HF). . A part of the mist 60 containing the solid substance accompanying the gas falls to the bottom surface of the absorption tower outlet 50 and returns to the absorption tower 4, and the mist 60 containing the remaining solid substance is removed by the mist eliminator 5. It is returned to the absorption tower 4 via the mist eliminator drain pipe 61. The clean exhaust gas 2 that has exited the mist eliminator 5 passes through the outlet flue 6 and is reheated as necessary to be discharged from a chimney (not shown).
[0014]
Limestone, which is an SOx absorbent, is supplied as a limestone slurry from a limestone slurry tank 15 (see FIG. 3) to a liquid reservoir in the absorption tower 4 by a limestone slurry pump 17 (see FIG. 3). The limestone slurry supply amount at this time is adjusted by the limestone slurry flow rate control valve 18 (see FIG. 3) according to the SOx absorption amount. The absorption liquid is pressurized by the absorption tower circulation pump 7 and supplied to the spray stage 8 in the absorption tower 4. The SOx removed in the absorption tower 4 reacts with calcium in the absorption liquid to become calcium sulfite (including calcium bisulfite) as an intermediate product, and the air supplied to the absorption tower 4 from the introduced oxidizing air As a result, it is oxidized to gypsum to form a final product (gypsum). By supplying air directly into the absorption tower 4 in this manner, the entire reaction is promoted by simultaneously progressing the SOx absorption reaction in the exhaust gas and the oxidation reaction of the generated calcium sulfite, and the desulfurization performance is improved. At that time, the oxidizing air supplied to the absorption tower 4 is refined by the oxidizing stirrer 26 to increase the utilization rate of the oxidizing air.
[0015]
In the configuration shown in FIG. 1, the absorption tower outlet 50 is provided with an inclined part having a downward slope in the same direction as the absorption tower outlet gas flow 51, and the absorption tower outlet drain 52 is returned to the absorption tower 4 at the lower end of the inclined part. An outlet drain pipe 54 is provided.
[0016]
By providing a downward slope along the absorption tower outlet gas flow 51 at the bottom surface of the absorption tower outlet section 50, the mist 60 containing the solid matter falling on the bottom surface becomes the absorption tower outlet drain 52 and the bottom surface. When flowing, the absorption tower outlet gas flow 51 and the absorption tower outlet drain flow 53 are in the same direction, so that the absorption tower outlet drain 52 easily flows.
[0017]
Since the absorption tower outlet drain flow 53 flows in the same direction as the absorption tower outlet gas flow 51 in this way, the absorption tower outlet drain 52 easily flows, and solids do not easily accumulate on the bottom surface of the absorption tower outlet 50. Thereafter, the absorption tower outlet drain 52 is returned to the absorption tower 4 via the absorption tower outlet drain pipe 54. In addition, since the inclined part of the bottom face of the absorption tower outlet 50 is directed downward along the absorption tower outlet gas flow 51, the tower height of the absorption tower 4 can be lowered.
[0018]
In addition, as shown in FIG. 2, a mist eliminator drain pipe 61 may be installed on the upstream side of the mist eliminator 5 so that it can also be used as the absorption tower outlet drain pipe 54.
[0019]
【The invention's effect】
According to the present invention, since it is possible to prevent solids from being deposited on the bottom surface of the absorption tower outlet, it is possible to reduce the work of removing accumulated solids during periodic inspection of the apparatus and to reduce the tower height of the absorption tower. effective.
[Brief description of the drawings]
FIG. 1 shows the structure of an absorption tower outlet of a wet flue gas desulfurization apparatus according to an embodiment of the present invention.
FIG. 2 shows the structure of the absorption tower outlet of the wet flue gas desulfurization apparatus according to the embodiment of the present invention.
FIG. 3 shows a system of a conventional wet flue gas desulfurization apparatus.
FIG. 4 shows a structure of an absorption tower outlet of a conventional wet flue gas desulfurization apparatus.
[Explanation of symbols]
1 Combustion exhaust gas from boilers, etc. 2 Clean exhaust gas 3 Inlet flue 4 Absorption tower 5 Mist eliminator 6 Outlet flue 7 Absorption tower circulation pump 8 Spray stage 9 Extraction pump 10 Gypsum dewatering equipment 11 Spray nozzle 12 Separated by gypsum dewatering equipment Water 13 Replenishment water in system 14 Drainage 15 Limestone slurry tank 16 Wastewater treatment facility 17 Limestone slurry pump 18 Limestone slurry flow control valve 19 Filtration tank 20 Filtrate pump 26 Oxidizing stirrer 30 pH meter tank 31 pH meter 41 Inlet SOx meter 42 Outlet SOx meter 50 Absorption tower outlet 51 Absorption tower outlet gas flow 52 Absorption tower outlet drain 53 Absorption tower outlet drain flow 54 Absorption tower outlet drain pipe 60 Mist containing solid matter 61 Mist eliminator drain pipe 64 Regulating valve

Claims (3)

In a wet-type flue gas desulfurization apparatus equipped with an absorption tower that absorbs and removes dust and sulfur oxides contained in combustion exhaust gas discharged from a combustion apparatus including a boiler by an absorbent liquid made of an absorbent slurry containing limestone or lime. ,
The ceiling surface of the absorption tower outlet to the horizontal plane, the absorption tower wet flue gas desulfurization apparatus is characterized in that the provided inclined portion inclined downward from the starting end of the bottom face in the same direction as the gas flow in the outlet portion.  The wet flue gas desulfurization apparatus according to claim 1, wherein a drain line is installed at a lower end of the inclined portion at the bottom of the absorption tower outlet.  The wet flue gas desulfurization apparatus according to claim 1, wherein a mist eliminator is disposed downstream of the inclined portion, and a drain pipe of the mist eliminator is shared with a drain line provided at a lower end of the inclined portion.

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