JPH0938447A - Liquid absorbent dispersing equipment and flue gas desulfurizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liq. absorbent dispersing equipment capable of uniformly dispersing a liq. absorbent. in an absorption tower and making the concn. distribution of the absorbent droplets uniform, suppressing the channeling in an absorption part and attaining high desulfurization performance and to provide a flue gas desulfurizer provided with the dispersing equipment. SOLUTION: A liq. absorbent jetted from plural jet pipes 22 are collided against a dispersion plate 23 in the form of a film, the mixing of the jetted absorbents is prevented by a partition plate 24, and the absorbent is uniformly distributed in the tower. Since the section of the gas passage is uniformly covered with the jetted absorbent, the channeling of the waste gas in the tower is minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flue gas desulfurization device for removing harmful components in a boiler exhaust gas, and in particular, an absorption liquid is uniformly dispersed under a high gas flow rate condition to suppress the influence of gas drift as much as possible. The present invention relates to a liquid dispersion device.

[0002]

2. Description of the Related Art In recent years, the natural environment surrounding the earth has deteriorated, and in particular, the absolute amount of SO ₂ gas emitted from thermal power plants installed in various parts of the world has a large impact on the environment. It is considered that the reduction of SO ₂ gas emission amount by using the flue gas desulfurization device is indispensable for taking measures against environmental pollution.

At present, as a flue gas desulfurization system, a spray type desulfurization device by the wet limestone-gypsum method is predominant due to its established technology and high reliability. However, the installation of the spray-type desulfurization device requires a great deal of cost, so that the penetration rate in developing countries is low, and it is urgent to provide a cheaper desulfurization device.

An example of a conventional spray type flue gas desulfurization apparatus is shown in FIG. The spray type flue gas desulfurization apparatus mainly includes an absorption tower body 1, an inlet duct 2, an outlet duct 3, a spray nozzle 4, an absorbent circulating pump 5, an oxidation tank 6, an agitator 7, an air blowing pipe 8, a mist eliminator 9, and the like. To be done.
A plurality of spray nozzles 4 are installed in the direction orthogonal to the exhaust gas flow, and a plurality of stages are installed in the gas flow direction. Further, the agitator 7 and the air blowing pipe 8 are installed in the oxidation tank 6 in the lower part of the absorption tower where the absorbing liquid stays, and the mist eliminator 9 is installed in the outlet duct 3.

Exhaust gas discharged from a boiler (not shown) is introduced from an inlet duct 2 into an absorption tower body 1 by a desulfurization fan.
And is discharged from the outlet duct 3. During this period, the absorption liquid containing calcium carbonate sent from the absorption liquid circulation pump 5 is sprayed from the plurality of spray nozzles 4 to the absorption tower main body 1, and the absorption liquid and the exhaust gas are brought into gas-liquid contact. At this time, the absorbing liquid selectively absorbs SO ₂ in the exhaust gas to generate calcium sulfite. The absorbing liquid that has produced calcium sulfite is accumulated in the oxidation tank 6, and while being stirred by the agitator 7 for oxidation, oxygen in the air supplied from the air blowing pipe 8 oxidizes the calcium sulfite in the absorbing liquid to produce gypsum. Part of the absorption liquid in the oxidation tank 6 in which calcium carbonate and gypsum coexist is absorbed by the absorption liquid circulation pump 5.
Is again sent to the spray nozzle 4 and a part of it is sent to the gypsum recovery system (not shown) from the absorbent extracting pipe 10. Further, among the absorbing liquids atomized and sprayed from the spray nozzle 4, those having a small droplet diameter are entrained in the exhaust gas, but are recovered by the mist eliminator 9 provided in the outlet duct 3.

A conventional hollow cone type spray nozzle 4 has been used as an absorbent dispersion device in a desulfurizer, but as shown in FIG. 8, when this type of spray nozzle 4 is used, the absorbent density immediately after spraying the absorbent is high. It has a characteristic that it is high and then gradually lowers. Therefore, the exhaust gas 12 tries to flow in a place where the liquid density is low, that is, where the resistance is low. Normally, a plurality of spray nozzles 4 (see FIG. 5) are installed at equal intervals in a single-stage spray header. Due to the characteristics of the spray nozzle 4, it is considered that the cross section can have a high and low liquid density distribution. As a result, the exhaust gas 12 tries to flow in a portion having a low liquid density, so that a non-uniform flow of gas occurs, and this tendency becomes more remarkable as the flow velocity of the exhaust gas 12 increases. This apparently lowers the liquid-gas ratio, which causes a decrease in desulfurization performance. In addition, a spray header is normally inserted in the absorption tower in order to evenly arrange the spray nozzles 4, but in order to make the spray liquid amount per spray nozzle 4 uniform, the flow velocity in the spray header piping is constant. As a countermeasure against this, as the spray header piping goes from the base to the tip,
It is designed to be gradually thinner.

Referring to FIG. 5, the absorbing liquid 25 is sprayed from the spray nozzle 4, but comparing the amount of absorbing liquid flowing through the spray header pipe 31 and the pipe 32 having a smaller diameter on the tip side thereof, the amount of liquid inside the pipe 32 is compared. Is 2 than that of pipe 31
The amount is reduced by the amount sprayed by the spray nozzles 4.
If the pipe diameters of the pipe 31 and the pipe 32 are equal, the flow velocity in the pipe 32 decreases, and the amount of the absorbing liquid sprayed from the spray nozzles 4 installed in both the pipe 31 and the pipe 32 is installed in the pipe 31. The phenomenon that the amount of the absorbed liquid from the spray nozzle 4 becomes larger than that of the pipe 32 occurs. This is the pipe 32 and the pipe 3 having a smaller diameter on the tip side than the pipe 32.
The same thing can be said during period 3. Therefore, it is necessary to gradually reduce the pipe diameter from the pipe 31 to the pipe 33 in order to make the flow velocity in the pipe constant and to make the amount of the absorbing liquid sprayed from each spray nozzle 4 uniform. Also, by making the pipe diameter small and keeping the flow velocity in the pipe constant, clogging in the spray nozzle 4 or the pipe can be prevented.

[0008]

However, making the pipe diameter of the spray header thinner as it goes to the tip as described above changes the projected area thereof and partially changes the cross-sectional area of the absorption tower. become. Therefore, under a high gas flow rate condition, a gas nonuniform flow occurs in the absorption tower, and the gas nonuniform flow adversely affects the desulfurization performance. In addition, when the absorbent is sprayed from the ceiling of the absorption tower using the hollow cone type spray nozzle 4 as shown in FIG. 6, when viewed from the side, the spray nozzle 4 can spray the absorbent only in a fan shape. In the vicinity of the ceiling portion (indicated by diagonal lines in the figure), there is a portion where there are no absorbed liquid droplets, and the exhaust gas blows through this portion, resulting in a significant decrease in desulfurization performance.
That is, in this method, the concentration distribution of the absorbing liquid droplets exists in the absorption tower, and under the high gas flow rate condition, the desulfurization performance due to the gas drift is not sufficiently taken into consideration.

Further, at present, the absorption tower tends to be compact, and due to the reduction of the diameter of the absorption tower, the internal velocity in the spray portion is gradually increasing as compared with the conventional case. Under such a background, if a spray section in which a spray header is inserted is installed in the tower as in the conventional case, the projected area in the tower by the pipe and the spray nozzle is increased, and the pressure loss is greatly increased. In addition, a method in which the absorbing liquid is usually sprayed in a direction orthogonal to the gas flow is often used, and since the pressure loss due to the absorbing liquid spraying increases due to the increase in the flow velocity in the column, the absorption of the conventional desulfurization apparatus shown in FIG. The power of the liquid circulation pump 5 cannot be reduced. By the way, about 80% of the power ratio of the conventional desulfurization device is occupied by the absorbing liquid circulating pump 5 and a fan (not shown), and the reduction of the power of the absorbing liquid circulating pump 5 leads to a significant reduction in operating cost.

Therefore, the object of the present invention is to make it possible to evenly disperse the absorbing liquid in the absorption tower and to make the concentration distribution of the absorbing liquid droplets uniform, to suppress uneven flow in the absorbing portion, and to achieve high desulfurization performance. It is an object of the present invention to provide an absorbent dispersion device that can be obtained and a flue gas desulfurization device including the absorbent dispersion device.

Further, an object of the present invention is to provide an absorption liquid dispersion apparatus capable of reducing the power of the absorption tower circulation pump while suppressing the pressure loss of the gas flow due to the absorption liquid spray in the absorption tower and without lowering the desulfurization performance. Another object of the present invention is to provide a flue gas desulfurization apparatus equipped with the absorbent dispersion device.

[0012]

The above object of the present invention is achieved by the following constitution. That is, a device for dispersing an absorption liquid in the exhaust gas in order to remove harmful components in the exhaust gas discharged from a combustion device such as a boiler, the absorption liquid ejection pipe and an absorption liquid provided in the vicinity of the absorption liquid ejection pipe outlet It is an absorption liquid dispersion device, characterized in that it comprises a dispersion plate which collides the liquid and spreads it into a film shape.

In the absorbent dispersion device of the present invention, the absorbent jet is composed of a plurality of jets branched from the absorbent pipe, and each absorbent jet is partitioned by a partition plate provided in the absorbent pipe. Can be configured. Further, it is desirable that the dispersion plate is attached to the absorbing liquid pipe so that the vertical cross section thereof is inclined with respect to the horizontal.

Further, the present invention also includes a flue gas desulfurization device in which the above absorbing liquid dispersion device is installed in order to remove sulfur oxides contained in exhaust gas from a boiler or the like.

According to the present invention, the gas in the horizontal part of the absorption tower or the inlet duct part of the absorption tower is used by using the absorption liquid dispersion device in which the absorption liquid discharged from the absorption liquid jet pipe is collided with the dispersion plate and spread on the film. It is possible to evenly cover the entire flow path cross-sectional direction with the absorbing liquid. By uniformly covering the entire cross section of the gas flow path, the liquid density of the absorbing liquid becomes uniform, so that there is no gas drift and a uniform flow having no velocity distribution is formed. SO ₂ in the exhaust gas is removed as the exhaust gas passes through the uniform film of the absorbent.

As a method for dispersing the absorption liquid, the absorption liquid whose pressure is increased to a horizontal part of the absorption tower or an inlet duct part of the absorption tower is immediately jetted from the upper part using a pipe by a pump for supplying the absorption liquid, Immediately (below) the dispersion plate is arranged to form the absorbing liquid in the form of a film. Further, a partition plate is provided in the flow direction of the absorbing liquid so that the absorbing liquid discharged from the plurality of tubes is not mixed, so that the distribution of the absorbing liquid in the tower becomes uniform. Thereby, it becomes possible to suppress the drift of the exhaust gas in the absorption tower as much as possible.

Therefore, in the conventional system, the back pressure was 0.8 kg / cm ² by using the hollow cone nozzle, whereas in the present invention, almost no back pressure is required to disperse the absorbing solution. Since the membrane part is formed very thin (within 1 cm), the pressure loss in the spray part is very small, and because it is easily miniaturized by the kinetic energy of the exhaust gas, gas-liquid contact between the exhaust gas and the absorbing liquid that acts on the reaction The area is not reduced and the reaction is expedited.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. A flue gas desulfurization apparatus using the absorbent dispersion apparatus of this example is shown in FIG. Similarly to the conventional absorption tower shown in FIG. 7, the flue gas desulfurization apparatus of this embodiment has an absorption tower body 1, an inlet duct 2, an outlet duct 3, a spray nozzle 4, a circulation pump 5, an oxidation tank 6, an agitator 7, air. The blowing tube 8 and the mist eliminator 9 are included. However, in this embodiment, the absorbent dispersion unit 11 provided with a partition plate (not shown) is installed on the ceiling of the inlet duct 2 having a high gas flow rate on the upstream side of the absorption tower, and the absorption liquid circulation for the liquid dispersion unit is further provided. The pump 14 is provided separately from the circulation pump 5. The absorption liquid sent from the circulation pump 14 is ejected from the absorption liquid dispersion section 11 and atomized by the high-velocity exhaust gas introduced from the gas inlet duct 2 to absorb SO ₂ in the exhaust gas.

Next, details of the absorbent dispersion unit 11 will be described with reference to FIGS. 1 and 2. The absorbent dispersion unit 11 includes a pipe 21 whose longitudinal direction is oriented in a substantially horizontal direction, a plurality of ejection pipes 22 attached downward to the side surface of the pipe 21 at appropriate intervals, and below the outlet of the ejection pipe 22. A dispersion plate 23 provided at intervals with its longitudinal direction along the axial direction of the pipe 21, and the dispersion plate 23 and the pipe 21 are connected, and a plurality of ejection pipes 2
It is composed of a plurality of partition plates 24 for partitioning between the two. Dispersion plate 23
The vertical section is supported by the partition plate 24 so as to be inclined with respect to the horizontal as shown in FIG. FIG.
Shows an example in which the absorption liquid dispersion part 11 is provided in the recess 2a provided in the ceiling of the absorption tower inlet duct 2, but the absorption liquid dispersion part 11 is not limited to the absorption tower inlet duct 2 and may be provided in the absorption tower. Can be provided in the horizontal part of the.

The absorption liquid supplied to the absorption liquid dispersion section 11 is branched from the pipe 21 into a plurality of ejection pipes 22 and drops downward in the vertical direction. Since the dispersion plate 23 is obliquely installed in this process, when the absorption liquid collides with the dispersion plate 23, the dispersion plate 23 spreads like a film and covers the cross section of the gas passage (duct). Further, in order to prevent the absorption liquids ejected from the respective ejection pipes 22 from interfering with each other and causing a concentration distribution due to the absorption liquids, a partition plate 24 is installed so that the absorption liquids are evenly dispersed in the duct. Will be possible.

In this apparatus structure, the absorbent dispersion unit 11 for dispersing the absorbent is installed in the horizontal part in the absorption tower or in the absorption tower inlet duct 2 so that an insert (spray header) installed in the tower can be installed. Since the number of arrangements can be reduced, the construction cost associated therewith can be significantly reduced. Further, since there is no insert in the absorbing liquid dispersion section 11 and the absorbing liquid can be uniformly dispersed, there is no influence of gas drift in the tower, and the gas flow velocity distribution is almost constant, so desulfurization accompanying it There is no performance degradation.

In order to reduce the power cost of the absorbent circulating pump 5, a method of simply reducing the spray back pressure can be considered.
In this method, since the amount of the spray liquid of the absorbing liquid is reduced and the absolute number of the spray nozzles 4 is increased, the cost thereof and the number of headers for mounting the spray nozzles 4 are increased, which leads to an increase in construction cost and is high. It is not preferable for treating exhaust gas with a high SO ₂ concentration, which requires a liquid-gas ratio. However, in this embodiment, since the absorption liquid is dispersed in the form of a liquid film from the horizontal part of the absorption tower or the upper part of the absorption tower inlet duct 2, high SO
₍₂₎ Even if the amount of circulating liquid is increased as a countermeasure, it is sufficient to increase the number of liquid films to be formed, and therefore the equipment cost does not increase so much.

When the absorbing liquid is sprayed using a general hollow cone type spray nozzle, the absorbing liquid forms liquid droplets having a wide particle size distribution. Accompanied to reach the Mist Eliminator 9. This tendency becomes more remarkable as the gas flow velocity in the absorbent spray portion is increased, and the higher gas flow velocity causes an increase in the load on the mist eliminator 9. However, in the method of the present embodiment, since the absorbing liquid is made fine by the kinetic energy of the exhaust gas, the droplet size of the absorbing liquid is relatively uniform, the droplet mist entrained by the exhaust gas is small, and the entrained liquid is small. Mist eliminator 9 because the droplets have a relatively large particle size
It is easy to collect by.

The pressure loss is smaller than that of the conventional method in which the absorbing liquid is sprayed in the counter flow in the exhaust gas, and the pressure loss does not increase abnormally even when the exhaust gas flow velocity is increased.

Further, since the conventional ceramic hollow cone type spray nozzle is not used, the cost of the absorbing liquid spray portion itself and the construction cost related to the mounting work are greatly reduced.

When the absorbing liquid is sprayed in the direction orthogonal to the gas flow using a normal hollow cone nozzle, the pressure loss in the absorbing liquid spray portion increases in correlation with the flow velocity in the column and the circulating liquid amount of the absorbing liquid. Therefore, it can be arranged as a function of the liquid-gas ratio. Comparing this example with the conventional technique under the condition that the liquid-gas ratio and the flow velocity in the tower are constant, the pressure loss in the case of the present example is about 60% of that of the conventional technique. On the other hand, the desulfurization performance was almost the same, and it was confirmed that the absorption liquid dispersion device was very excellent.

Another embodiment of the present invention is shown in FIG. The embodiment shown in FIG. 4 is systematically similar to the device shown in FIGS. 1 and 2, but since the vertical section of the dispersion plate 23 is V-shaped, the absorption liquid ejected from the pipe 21 is It is different from the embodiments of FIGS. 1 and 2 in that it can be dispersed in two directions by the dispersion plate 23. By dispersing the absorbent in two directions,
The absorbing liquid can be dispersed in the co-current direction and the counter-current direction with respect to the gas flow, and the pressure loss of the gas flow is reduced as compared with the case where the absorbing liquid is dispersed only in the counter-current direction.

[0028]

According to the present invention, the pump head of the absorbing solution sprayed in the exhaust gas can be lowered and the pressure loss can be reduced without lowering the desulfurization performance. Therefore, the pump and fan for absorbing the absorbing solution can be reduced. It is possible to reduce power and the like. At the same time, since the hollow cone nozzle is not used unlike the conventional device, it is possible to reduce the equipment cost and the cost related thereto. Further, since the spray droplets of the absorbing liquid are relatively uniform, the amount of mist scattered is small, which leads to a reduction in the load of the mist eliminator.

[Brief description of drawings]

FIG. 1 is a structural diagram of an absorbent dispersion unit according to an embodiment of the present invention.

FIG. 2 is a side sectional view when the absorbent dispersion unit of FIG. 1 is arranged in an absorption tower inlet duct.

FIG. 3 is a schematic view of the absorbent dispersion device of one embodiment of the present invention applied to a desulfurization device.

FIG. 4 is a side sectional view of an embodiment of the present invention in which an absorption liquid dispersion section for separating the absorption liquid in two directions is arranged in an absorption tower inlet duct.

FIG. 5 is a perspective view when a spray nozzle is used as an absorbent dispersion device of a conventional device.

FIG. 6 is a diagram showing a spraying state of an absorbing liquid when a spray nozzle is attached to a ceiling portion of an absorption tower inlet duct.

FIG. 7 is a diagram showing a conventional absorption tower structure.

FIG. 8 is a diagram showing a gas flow state when the absorbing liquid is sprayed using a spray nozzle.

[Explanation of symbols]

1 absorption tower main body 2 inlet duct 3 outlet duct 4 spray nozzle 5 circulation pump 6 oxidation tank 7 stirrer 8 air blowing pipe 9 mist eliminator 11 absorbing liquid dispersion part 14 absorbing liquid circulation pump 21 pipe 22 jet pipe 23 dispersion plate 24 partition plate

Front page continuation (72) Inventor Hirofumi Yoshikawa 3 36 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Laboratory (72) Inventor Hiroshi Ishizaka 3 36 Takaracho, Kure City, Hiroshima Prefecture Kure Laboratory, Babcock Hitachi Ltd.

Claims (5)

[Claims] 1. A device for dispersing an absorption liquid in an exhaust gas to remove harmful components in the exhaust gas discharged from a combustion device such as a boiler, the absorption liquid injection pipe and an outlet in the vicinity of the absorption liquid injection pipe outlet. An absorption liquid dispersion device, comprising: a dispersion plate that collides the provided absorption liquid and spreads it into a film. 2. The absorbent dispersion device according to claim 1, wherein the absorbent jet comprises a plurality of jets branched from the absorbent pipe. 3. The absorbent dispersion device according to claim 1, wherein each absorbent jet is divided by a partition plate provided in the absorbent pipe. 4. The absorbent dispersion device according to claim 1, wherein the absorbent plate is attached to the absorbent pipe so that the vertical section of the dispersion plate is inclined with respect to the horizontal. 5. A flue gas desulfurization device equipped with the absorbent dispersion device according to claim 1 for removing sulfur oxides contained in exhaust gas from a boiler or the like.