JP2003103139A - Wet process flue gas desulfurizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet process flue gas desulfurizer having an absorption column which prevents the degradation of a desulfurization rate by short passing of an absorbing solution having a low pH value to circulation piping and averts increasing of draft loss by accumulation of the absorbing solution and gypsum scale particularly to its base surface region. SOLUTION: An overhanging length B of a shielding plate 15 integral with the base surface of an inlet duct 2 for the waste gas to be treated into the absorption column is made to be the same as the width W of a baffle plate 10 existing in the section right below the same or greater than the same so that the shielding plate 15 prevents the desulfurized absorbing solution of the low pH value from flowing down directly between the baffle plate 10 and a circulating tank 16. The absorbing solution flowing down from the absorption column 1 through the shielding plate 15 to the central segment of the tank 26 parts the absorbing solution of the low pH value not absorbing SOx from the baffle plate 10 and mixes the same with the absorbing solution of the different pH value absorbing the SOx to mix the absorbing solution with oxidizing air 9 with better contact therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet flue gas desulfurization apparatus for combustion exhaust gas from a boiler or the like.

[0002]

2. Description of the Related Art In order to prevent air pollution, a desulfurization device by a wet limestone-gypsum method has been widely put into practical use as a device for removing sulfur oxides from combustion exhaust gas of fossil fuels. FIG. 7 shows a conventional cylindrical self-supporting spray type return flow absorption tower which is the main equipment of this desulfurization apparatus, and FIG. 8 shows a plan view of the gas inlet / outlet portion thereof (a view taken along the line BB in FIG. 7).

The cylindrical self-supporting spray type return flow absorption tower 1 shown in FIG. 7 is provided with a gas inlet duct 2 on the side wall and a gas outlet duct 7 on the side wall opposite to the gas inlet duct 2, and the inside space of the absorption tower is provided. The partition plate 6 is arranged in the vertical direction. A flow passage space for the exhaust gas flowing in the tower is provided between the upper end of the partition plate 6 and the absorption tower ceiling wall, and the lower end of the partition plate 6 is an absorption liquid reserving tank 16 provided in the lower part of the absorption tower. It is immersed in the liquid.

Therefore, the exhaust gas flowing in from the gas inlet duct 2 is changed in its flow direction by the partition plate 6, rises in the absorption tower 1 and changes to a downward flow after passing through the partition plate 6, and the gas outlet duct 7 is formed. Emitted from.

A spray provided with a large number of spray nozzles 4 and 5 for spraying an absorbing liquid composed of a carbonate slurry such as limestone slurry in a region where an ascending flow and a descending flow of gas in an absorption tower partitioned by the partition plate 6 are provided. Plural stages of the pipe 3 are provided.

Combustion exhaust gas g1 containing sulfur oxides and soot generated from a boiler or the like in a thermal power plant is guided to the absorption tower 1, and the flow path of the absorption tower 1 is forcibly changed by a partition plate 6. Ascending flow (upflow), and a large number of spray nozzles 4 in between, an absorption liquid spray pipe 3
Are installed at least in two or more stages orthogonal to the gas flow, and form a counter flow with the absorbing liquid sprayed as fine liquid droplets from the spray nozzle 4.

After the exhaust gas flows between the absorption tower ceiling and the partition plate 6, in a region where a gas downflow occurs, in the example shown in FIG. 7, the spray nozzle 5 for spraying the absorbing liquid descends the gas. The spray pipe 3 is provided so as to be in parallel with the flow, and the spray pipe 3 is provided in a plurality of stages (the spray pipe 3 may be provided so that the spray nozzle 5 is in a counterflow with the gas downward flow). ).

The ascending and descending flows of the exhaust gas come into gas-liquid contact with the absorbing liquid sprayed from the spray nozzles 4 and 5, so that the sulfur oxides in the exhaust gas are absorbed and removed through the surface of the absorbing droplets, and soot and dust are collected. Are physically removed by collision with the droplets.

Minute droplets (mist) entrained in the exhaust gas flow are removed by a mist eliminator (not shown) installed outside the absorption tower 1, and the purified treated exhaust gas g2 is, if necessary, a gas duct (at the downstream side of the absorption tower). The temperature is raised by a reheating facility installed (not shown) and discharged from the chimney into the atmosphere.

On the other hand, the absorbing droplets sprayed from the absorbing liquid spray nozzles 4 and 5 absorb the sulfur oxides in the exhaust gas, and
It falls into the absorption liquid circulation tank 16 provided in the lower part of the absorption tower.

The sulfur oxides absorbed in the absorption tower 1 react with the limestone slurry supplied to the absorption liquid circulation tank 16,
At the same time, the oxidizing air 9 is introduced from the side wall of the circulation tank 16, and the oxidizing air 9 is atomized by the oxidizing stirrer 8 to oxidize the sulfur oxides in the absorbing liquid to produce gypsum.

As described above, since gypsum exists as a solid substance in the absorbent stored in the absorbent circulation tank 16, precipitation is prevented by a slurry agitator (not shown). A circulation pump 11 for withdrawing the absorbing liquid from the absorbing liquid circulating tank 16 and supplying the circulating liquid to the spray nozzles 4, 5 and an absorbing liquid circulating pipe 12 are provided, and an opening portion of a side wall of the circulating tank 16 to which the absorbing liquid circulating pipe 12 is connected. A baffle plate 10 is provided to cover the. The baffle plate 10 is a member for blocking the bubbles of the oxidizing air 9 that have been miniaturized by the oxidizing agitator 8 so as not to flow into the absorbing solution circulation pipe 12, and the upper side thereof is open, and the absorbing solution is opened. After removing the atomized air 9 in the absorption liquid in the circulation tank 16, the absorption liquid is boosted by the absorption liquid circulation pump 11 and is guided to the absorption liquid spray pipe 3 again through the absorption tower circulation pipe 12 to be absorbed by the absorption liquid spray nozzle. It is sprayed from 4 and 5.

[0013]

In the prior art shown in FIG. 7, the pH of the absorbing liquid dropped to the absorbing liquid circulating tank 16 immediately below the gas inlet duct 2 of the absorption tower 1 is first determined by the exhaust gas g1 to be treated and the absorbing liquid. Since it is in contact with, the pH is about 3 to 4. This pH value is lower than the pH value of about 5 to 6 of the absorbing liquid which has dropped into the absorbing liquid circulation tank 16 after being sufficiently in gas-liquid contact with the exhaust gas like the gas outlet duct 7 side.

As shown in FIG. 7, in order to reduce the installation area of the desulfurization equipment, the heat recovery side portion of a heat exchanger (not shown) arranged in the gas inlet duct 2 or in the exhaust gas flow path upstream thereof. When the absorption liquid circulation pump 11 is installed using the empty space on the lower surface, the absorption liquid having a low pH value short-passes to the circulation pipe 12 and is supplied to the absorption liquid spray pipe 3 and the absorption liquid spray nozzles 4 and 5. Therefore, the desulfurization rate of the exhaust gas may decrease. For this reason, the arrangement position of the absorption liquid outlet to the circulation pipe 12 on the side wall of the circulation tank 16 is restricted, and the handling length of the circulation pipe 12 is increased or the volume of the absorption liquid circulation tank 16 is increased. It was necessary to take measures such as prolonging the retention time of the absorption liquid and recovering the pH value, leading to an increase in the cost of the device.

The object of the present invention is to prevent the absorption liquid having a low pH value from short-pathing to the absorption liquid circulation pipe to lower the desulfurization rate, and to prevent the absorption liquid and the gypsum scale around the gas inlet duct, especially the bottom surface region thereof. It is an object of the present invention to provide a wet flue gas desulfurization apparatus having an absorption tower that avoids the accumulation of air and increases the ventilation loss.

[0016]

The above object of the present invention can be achieved by the following constitution. That is, the gas inlet duct for the gas to be treated and the gas outlet duct for contacting the gas to be treated introduced from the gas inlet duct with the absorbing liquid to remove the sulfur oxides in the gas and discharging the exhaust gas after desulfurization treatment An absorption tower provided with, and storing the absorption liquid in the lower part of the absorption tower,
Also, in a wet flue gas desulfurization device equipped with an absorbing liquid circulation tank for supplying a part of the stored absorbing liquid into the absorption tower body to bring the gas to be treated into contact with the absorbing liquid, the absorbing liquid circulation pipe is connected to the gas inlet duct. Attached to the absorption liquid circulation tank below the connection with the absorption tower, the bubbles in the absorption liquid are in the absorption liquid circulation pipe in the absorption liquid circulation tank facing the absorption liquid circulation pipe mounting part of the absorption liquid circulation tank. A position where a baffle plate for preventing inflow is provided, and it is located between the connection part of the gas inlet duct for the gas to be treated with the absorption tower and the liquid level of the absorption liquid in the absorption liquid circulation tank and covers the upper part of the baffle plate. It is a wet flue gas desulfurization device having a shield plate connected to the bottom of the gas inlet duct.

The bottom surface of the inlet duct for the gas to be treated may be a downward inclined surface extending into the absorption tower, and the inclined surface may be the upper surface of the shielding plate.

The shielding plate has a tip portion near the center of the absorption tower, or has a triangular vertical cross-section with the side wall of the absorption tower on the absorbent liquid storage surface of the circulation tank as the bottom surface. It may have a certain configuration.

Further, the shielding plate may have a triangular vertical cross section with the bottom surface being the inside of the side wall of the absorption tower above the liquid level of the absorption liquid in the circulation tank.

Further, the absorption tower of the present invention is provided with an inlet duct and an outlet duct, and an exhaust gas passage between the inlet duct and the outlet duct, and the exhaust gas passage has two chambers on the inlet duct side and the outlet duct side. In order to divide into two parts, a vertically standing partition plate having an opening on the ceiling side is provided, and exhaust gas introduced from an inlet duct flows upward in the partition plate and is inverted at the ceiling side opening. A spray nozzle is formed in each of the above regions so that a downward flow region in which the exhaust gas flows downward toward the outlet duct is formed later, and the jetted absorbent slurry is in countercurrent contact with the exhaust gas in the upward flow region and in parallel flow contact in the downward flow region. It is possible to use an absorption tower having a configuration provided with.

The absorption tower of the wet flue gas desulfurization apparatus of the present invention is of a system in which the gas to be treated is introduced from the side wall surface of the absorption tower and the absorbent is sprayed vertically or horizontally to the gas to be treated in the absorption tower. It is an absorption tower.

[0022]

The operation of the present invention will be described by taking the flue gas desulfurization apparatus of FIG. 1 as an example. Operation of wet flue gas desulfurization equipment is treated exhaust gas
Before passing 1 through the absorption tower 1, a large amount of the absorption liquid is sprayed into the absorption tower from the absorption liquid spray nozzles 4 and 5 (this is referred to as "absorption liquid circulation"). Then, after a certain period of time has passed, the treated exhaust gas g1 is passed through the absorption tower 1 (this is referred to as normal operation).

The horizontal length B of the shield plate 15 integrated with the bottom surface of the gas inlet duct 2 into the absorption tower is the same as the width W of the baffle plate 10 located immediately below it, or the above-mentioned protrusion length B Is made larger than the width W of the baffle plate 10 so that the shielding plate 15 does not allow the desulfurized absorption liquid having a low pH value to flow directly onto the baffle plate 10 on the upflow side during normal operation.

Further, the circulation tank 16 is provided by the shield plate 15.
The absorbing liquid that is induced and flows down near the central portion of the is that the absorbing liquid having a low pH value on the upflow side is moved away from the baffle plate 10 and mixed with the absorbing liquid having a different pH value on the downflow side, and the oxidizing air 9 is supplied. It works so as to make contact and stirring better.

The low p dropped into the circulation tank 16 in this way
The absorbing liquid of H value does not pass through the baffle plate 10 by short-pass and directly mixes with the absorbing liquid on the downflow side in the absorbing liquid circulation tank 16, and further the oxidizing air 9
Since it becomes easier to stir by contacting with, the desulfurization rate can be improved with the same liquid / gas ratio.

Further, it is desirable that the bottom surface of the gas inlet duct 2 and the shield plate 15 have a gradient so that the absorbing liquid and the gypsum scale are not deposited. As a result, during circulation of the absorbing liquid, the slurry-like absorbing liquid flows down so as not to be deposited on the bottom surface of the gas inlet duct 2, so that the gypsum soft scale does not occur. Therefore, due to the high exhaust gas temperature, there is no possibility that water in the absorbing liquid will evaporate on the bottom surface of the gas inlet duct 2 and the shield plate 15 to form gypsum scale.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

EXAMPLE 1 FIG. 1 is a schematic cross-sectional view of a spray type return flow absorption tower 1 of this embodiment. The same members as those shown in FIG. 7 are designated by the same reference numerals and their description is omitted.

The feature of the present embodiment is that the bottom surface of the gas inlet duct 2 is extended to the inside of the absorption tower so that the top surface of the shielding plate 15 and the bottom surface of the gas inlet duct 2 form the same plane. 15 are arranged. FIG. 2 shows a view taken along the line AA of FIG. 1, showing the gas inlet duct 2, the gas outlet duct 7, the vicinity of the gas inlet duct 2, and the shield plate 15.

In this embodiment, the bottom surface of the gas inlet duct 2 is inclined downward. Further, the horizontal length of the protruding portion of the shield plate 15 into the absorption tower 1 is B, and both ends of the tip end portion of the shield plate 15 extend to the position in contact with the wall surface portion of the absorption tower 1. The length B is the same as the width W of the baffle plate 10.

The shield plate 15 has a triangular vertical cross-sectional shape. The downward inclination angle θ2 of the upper surface inclined portion with respect to the horizontal is 20 degrees, and the downward inclination angle θ3 of the lower surface inclined portion with respect to the horizontal.
Is 30 degrees, but it is sufficient if the angle does not cause plaster scaling, and the inclination angles θ2 and θ3 are not particularly limited.

The connection position of the shield plate 15 to the wall surface of the absorption tower 1 extends from the bottom surface of the gas inlet duct 2 to the inside of the absorption tower. It may be anywhere below the lower end of the opening as long as it is on the liquid surface of the absorbent circulation tank 16.

5 and 6 show an example of the structure of the shield plate 15 and the baffle plate 10. Shield plate 15 is shown in FIG.
FIG. 6 shows a perspective view of the baffle plate 10 and the mutual arrangement relationship in space, and FIG. 6 shows a view taken along the line DD of FIG. The low-pH absorption liquid Q1 sprayed from the spray nozzle 4 flows down and drops onto the shielding plate 15, where it changes direction and flows into the absorption liquid circulation tank 16 away from the baffle plate 10. On the other hand, the absorption liquid Q2, which has been mixed and stirred in the absorption liquid circulation tank 16 to recover the pH value, flows into the baffle plate 10 through the opening of the baffle plate 10, passes through the absorption liquid circulation pump 11, and is circulated and recirculated as an absorption liquid. used.

(1) Short path of low pH absorption liquid into the absorption liquid circulation pump is located at the bottom of the gas inlet duct 2 to the above-mentioned protruding length B of the shielding plate 15 into the tower and immediately below the shielding plate 15. Since the width W of the baffle plate 10 is the same or the overhang length B is larger than the width W of the baffle plate 10, the shielding plate 15 is desulfurized at the upflow side at low pH during normal operation. It is possible to prevent the absorbing liquid of the value from directly flowing down into the baffle plate 10.

The absorption liquid guided by the shield plate 15 and flowing down to the central portion of the circulation tank 16 keeps the absorption liquid having a low pH value on the upflow side away from the baffle plate 10 and has a different pH value on the downflow side. The absorbing liquid can be mixed in the circulation tank 16 to facilitate contact and stirring with the oxidizing air 9.

In this way, the absorbent having a low pH value that has fallen into the absorbent circulating tank 16 does not short-path and directly flow down to the baffle plate 10, and the absorbent circulating tank 1
Since it mixes with the absorbing liquid on the downflow side in 6 and is further brought into contact with the oxidizing air 9 to be stirred, the shielding plate 15
The desulfurization rate is further improved with the same liquid / gas ratio as compared with the absorption tower not provided with. Further, there is no need to increase the capacity of the absorption liquid circulation tank 16 and lengthen the residence time in order to recover the pH value of the absorption liquid.

The protruding length B of the shield plate 15 is such that the low pH absorption liquid that has fallen into the absorption liquid circulation tank 16 directly enters the absorption liquid inside the baffle plate 10 (between the wall surface of the tank 16 and the plate 10). If it does not flow down, B ≧ W
If the above condition is satisfied, the overhang length B is not particularly limited.

The range of the shield plate 15 seen from the plane is
As shown in FIG. 2, the baffle plate 10 may be covered, and the shape is not limited.

The shield plate 15 has a triangular vertical cross-section, the upper surface inclined portion has a downward inclination angle θ2 with respect to the horizontal of 20 degrees, and the lower surface inclined portion has a downward inclination angle θ3 with respect to the horizontal.
Is 30 degrees, but the inclination angles θ2 and θ3 are not particularly limited as long as the plaster is not scaled at this portion.

The connection position of the shield plate 15 to the wall surface of the absorption tower 1 extends from the bottom surface of the gas inlet duct 2 to the inside of the absorption tower, and the opening for connecting the gas inlet duct on the side wall of the absorption tower. It may be anywhere below the lower end of the part as long as it is on the liquid surface of the absorbing liquid circulation tank 16.

(2) Deposition, growth and cross-section blockage of gypsum scale on the bottom surface of the gas inlet duct 2 In the vicinity of the gas inlet duct 2, the treated exhaust gas at 100 to 200 ° C. and the absorbing liquid come into gas-liquid contact, and the exhaust gas Due to the high temperature, the water in the absorbing liquid (limestone slurry containing gypsum) evaporates and becomes gypsum scale that accumulates and grows on the bottom surface of the gas inlet duct 2 and causes an increase in the pressure loss of the ventilation system, resulting in large growth. There is a possibility that the scale pieces may drop into the absorption liquid circulation tank 16 and pass through the absorption tower circulation pipe 12 to eventually cause clogging of the absorption liquid spray nozzles 4 and 5.

Desirably, the gas inlet duct 2 having a shape in which a rectangular parallelepiped is connected to the cylindrical portion and its end is a portion connected to the opening of the side wall of the absorption tower 1 is a rectangular parallelepiped portion, which is conventionally horizontal. 2 where the gypsum in the absorbing liquid that has fallen from above does not accumulate in the area X'on the bottom surface of the gas inlet duct 2 (the area surrounded by the absorption tower sidewall and the dotted line portion of the gas inlet duct 2) shown in FIG. It is good to have a tilt angle.

As a result, the slurry-like absorption liquid circulating in the absorption tower 1 does not deposit on the bottom surface of the gas inlet duct 2 and always flows down to the absorption liquid circulation tank 16, so that the area X'is provided. Generation of gypsum soft scale can be suppressed.

Therefore, on the bottom surface of the gas inlet duct 2, 10
It is possible to prevent the moisture in the absorbing liquid from evaporating due to the exhaust gas having a high temperature of 0 to 200 ° C. to form and grow the gypsum scale, and to avoid the problems of ventilation loss and clogging of the spray nozzles 4 and 5.

Similarly, the bottom surface of the gas outlet duct 7 also has an inclination angle at which the gypsum in the absorbing liquid does not accumulate in the area Y'in FIG. 2 (the area surrounded by the side wall of the absorption tower and the dotted line portion of the gas outlet duct 7). It is better to let them.

The angle of inclination at this time is not particularly limited as long as it does not cause plaster scaling at this portion.

The baffle plate 1 shown in FIGS.
An example of the structure of No. 0 is shown, but the structure and shape are not limited unless the fine bubbles supplied from the oxidizing air 9 are sucked.

[0047]

Second Embodiment Another embodiment of the present invention is shown in FIGS. FIG. 3 shows a schematic cross-sectional view of the spray type return flow absorption tower 1 of the present embodiment, and FIG. 4 shows a view taken along the line CC of FIG. 3, showing a gas inlet duct 2 and a gas outlet duct 7.
And the vicinity of the gas inlet duct 2 and the shielding plate 15.

In this embodiment, the exhaust gas to be treated g1 and the sprayed absorbent are brought into gas-liquid contact in a horizontal direction in a parallel flow or a counter flow,
This is a method for desulfurization and is called a high-speed horizontal flow desulfurization device.

This system configuration is the same as that of the return flow type absorption tower shown in FIG. 1, but structurally different in that the absorbing liquid spray and the exhaust gas flow are horizontal flow type desulfurization devices.

A combustion exhaust gas g1 containing sulfur oxides and soot dust generated from a boiler or the like in a thermal power plant is guided to the absorption tower 1 in a horizontal direction, and a horizontal spray provided with a large number of spray nozzles 4 in the absorption tower 1. The absorption liquid spray pipe 3 extending in the direction sprays the absorption liquid in the direction opposite to the gas flow. Figure 3
In the example shown in (1), at least one stage spray pipe 3 is installed in the direction parallel to the flow of gas on the upstream side in the gas inlet duct 2 from the spray nozzle 4 of the spray pipe 3 on the more inlet side of the gas inlet duct 2. At least two stages are installed downstream of the gas inlet duct 2 from the spray nozzle 4 of the spray pipe 3 in a direction facing the gas flow.

The flow of the exhaust gas comes into gas-liquid contact with the absorbing liquid sprayed from the spray nozzle 4, whereby the sulfur oxides in the exhaust gas are absorbed and removed through the surface of the absorbing droplets, and the dust particles collide with the droplets. Are physically removed by.

Minute droplets (mist) entrained in the exhaust gas flow are removed by a mist eliminator (not shown) installed outside the absorption tower 1, and the purified treated exhaust gas g2 is, if necessary, a gas duct (at the downstream side of the absorption tower). The temperature is raised by a reheating facility installed (not shown) and discharged from the chimney into the atmosphere.

On the other hand, the absorption liquid droplets sprayed from the absorption liquid spray nozzle 4 absorb the sulfur oxides in the exhaust gas and then fall into the absorption liquid circulation tank 16 provided in the lower part of the absorption tower.

The sulfur oxide absorbed in the absorption tower 1 reacts with the limestone slurry supplied to the absorption liquid circulation tank 16,
At the same time, the oxidizing air 9 is introduced from the side wall of the circulation tank 16, and the oxidizing air 9 is atomized by the oxidizing stirrer 8 to oxidize the sulfur oxides in the absorbing liquid to produce gypsum.

As described above, since gypsum is present as a solid in the absorbent stored in the absorbent circulation tank 16, precipitation is prevented by a slurry agitator (not shown). A circulation pump 11 and an absorption liquid circulation pipe 12 for extracting the absorption liquid from the absorption liquid circulation tank 16 and circulating it to the spray nozzles 4 and 5 are provided, and the side wall of the circulation tank 16 to which the absorption liquid circulation pipe 12 is connected. The baffle plate 10 is provided to cover the opening. Baffle plate 1
0 indicates that the absorption liquid in the absorption liquid circulation tank 16 is an agitator 8 for oxidation.
The bubbles of the oxidizing air 9 that have been made fine by
It is a member to shut off so that it does not flow into 2,
The upper part is open, and after removing the atomized air 9 in the absorbing liquid in the absorbing liquid circulating tank 16, the absorbing liquid is pressurized by the absorbing liquid circulating pump 11, passes through the absorbing tower circulating pipe 12, and again. It is guided to the absorption liquid spray pipe 3 and sprayed from the absorption liquid spray nozzle 4.

The bottom surface of the gas inlet duct 2 is inclined downward. In addition, the shield plate 15 projects into the absorption tower 1,
The tip of the shielding plate 15 extends to a position in contact with the wall surface of the absorption tower 1, and its horizontal length B is the same as the width W of the baffle plate 10.

The shield plate 15 has a triangular vertical cross-sectional shape. The downward inclination angle θ2 of the upper surface inclined portion with respect to the horizontal is 20 degrees, and the downward inclination angle θ3 of the lower surface inclined portion with respect to the horizontal.
Is 30 degrees, but the angle is not particularly limited as long as the gypsum scaling does not occur at this portion.

Further, the connection position of the shield plate 15 to the wall surface portion of the absorption tower 1 extends from the bottom surface of the gas inlet duct 2 to the inside of the absorption tower 1, and the inlet duct connection of the side wall of the absorption tower 1 is performed. It may be anywhere below the lower end of the working opening as long as it is on the liquid surface of the absorbent circulating tank 16.

If there is no shielding plate 15 having an overhanging length B which is equal to or larger than the width W of the baffle plate 10, the desulfurized absorption liquid having a low pH value (pH = 3 to 4) is concentrated. Since it flows into the vicinity, the exhaust gas desulfurization rate is lowered if this low pH absorption liquid is directly sprayed from the spray nozzle 4 through the absorption tower circulation pipe 12. Therefore,
Slope (tilt angle) of gas inlet duct 2 and gas outlet duct 7
Also, if the structure of the shield plate is the same as that of the first embodiment shown in FIG. 1, the same effect can be obtained.

According to the present invention, although not shown, the gas to be treated which is not provided with the partition plate 6 in the absorption tower 1 shown in FIG. 1 is introduced from the side wall of the absorption tower, and the spray pipes 3 having a plurality of stages are arranged in the horizontal direction. The present invention is also applicable to a vertical absorption tower in which gas is subjected to countercurrent contact and / or cocurrent contact.

[0061]

According to the present invention, since the absorbent having a low pH value does not short-path to the absorbent circulating pipe, it is possible to prevent the desulfurization rate of the gas to be treated from being lowered, and particularly in the vicinity of the gas inlet duct, It is possible to prevent the absorption liquid and the gypsum scale from accumulating in the bottom surface area and increasing the ventilation loss.
As a result, it is possible to operate the desulfurizer stably for a long period of time, reduce operation and maintenance costs, and make the absorption tower compact.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a cylindrical self-supporting spray type return flow absorption tower of an embodiment of the present invention.

FIG. 2 is a perspective view taken along the line AA of FIG.

FIG. 3 is a schematic sectional view of a high-speed horizontal flow spray type breathing tower according to another embodiment of the present invention.

FIG. 4 is a perspective view taken along the line CC of FIG.

FIG. 5 is a bird's-eye view showing the relationship between the shield plate and the baffle plate (one example) of the present invention.

FIG. 6 is a side view of the baffle plate (one example) (view from DD in FIG. 5).

FIG. 7 is a schematic sectional view of a conventional cylindrical self-supporting spray type return flow absorption tower.

8 is a plan view of a gas inlet / outlet portion of a conventional absorption tower (FIG. 7).
BB view).

[Explanation of symbols]

1 Return Flow Absorption Tower 2 Gas Inlet Duct 3 Absorption Liquid Spray Pipe 4 Absorption Liquid Spray Nozzle 5 Absorption Liquid Spray Nozzle 6 Partition Plate 7 Gas Outlet Duct 8 Oxidation Stirrer 9 Oxidation Air 10 Baffle Plate 11 Circulation Pump 12 Absorption Tower Circulation Pipe 15 Shield plate 16 Absorbing liquid circulation tank g1 Treated exhaust gas g2 Treated exhaust gas W Baffle plate width θ Angle of baffle plate in circumferential direction B Shield plate overhang angle θ2 Shield plate upper surface inclination angle θ3 Shield plate lower surface inclination angle

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takao Asami             Babcock Hitachi 6-9 Takaracho, Kure City, Hiroshima Prefecture             Kure Office Co., Ltd. (72) Inventor Hiroshi Ishizaka             Babcock Hitachi 3-36 Takaracho, Kure City, Hiroshima Prefecture             Kure Institute Co., Ltd. F-term (reference) 4D002 AA02 AC01 BA02 CA01 CA20                       DA05 DA16 EA12 FA03

Claims (6)

[Claims] 1. A gas inlet duct for a gas to be treated and a gas for contacting the gas to be treated introduced from the gas inlet duct with an absorbing liquid to remove sulfur oxides in the gas and to discharge exhaust gas after desulfurization treatment. An absorption tower having an outlet duct, an absorption liquid for storing the absorption liquid in the lower part of the absorption tower, and supplying a part of the stored absorption liquid into the absorption tower main body to bring the gas to be treated into contact with the absorption liquid. In a wet flue gas desulfurization device equipped with a liquid circulation tank, the absorption liquid circulation pipe is attached to the absorption liquid circulation tank below the connection part of the gas inlet duct with the absorption tower, and the absorption liquid circulation pipe mounting part of the absorption liquid circulation tank is installed. A baffle plate that prevents bubbles in the absorbing liquid from flowing into the absorbing liquid circulation pipe is installed in the absorbing liquid circulation tank facing the With the liquid level of the absorbing liquid in the tank A is a wet flue gas desulfurization apparatus characterized in that a shielding plate to be connected to the vicinity of the gas inlet duct bottom at a position covering the upper side of the baffle plate. 2. The wet flue gas desulfurization apparatus according to claim 1, wherein the bottom surface of the inlet duct for the gas to be treated is a downward inclined surface extending into the absorption tower, and the inclined surface is the upper surface of the shielding plate. . 3. The wet flue gas desulfurization apparatus according to claim 1, wherein the shielding plate has a tip portion near the center of the absorption tower. 4. The wet flue gas desulfurization according to claim 1, wherein the shielding plate has a triangular vertical cross-section whose bottom surface is the inside of the side wall of the absorption tower above the liquid level of the absorption liquid in the circulation tank. apparatus. 5. The absorption tower has an inlet duct and an outlet duct.
An exhaust gas passage is provided between the inlet duct and the outlet duct,
In order to divide the exhaust gas flow path into two chambers, one on the inlet duct side and the other on the outlet duct side, a partition plate that stands vertically with an opening on the ceiling side is provided, and the exhaust gas introduced from the inlet duct by the partition plate After reversing in the upward flow region that flows upward and the opening on the ceiling side, a downward flow region in which the exhaust gas flows downward toward the outlet duct is formed, and the jetted absorbent slurry comes into countercurrent contact with the exhaust gas and the upward flow region, 2. The wet flue gas desulfurization apparatus according to claim 1, wherein a spray nozzle is provided in each of the areas so as to make parallel flow contact in the downflow area. 6. The absorption tower is an absorption tower of a system in which the gas to be treated is introduced from the side wall surface of the absorption tower and the absorbing liquid is sprayed vertically or horizontally to the gas to be treated in the absorption tower. The wet flue gas desulfurization apparatus according to claim 1.