JP2000354728A - Gas-liquid contact device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-liq. contact device capable of simultaneously solving the problem of high gas speed and the suppression of an increase in air ventilation loss. SOLUTION: In the gas-liq. contacting device operating at a high gas speed/ high liq. density of >=5m/s gas speed in a gas flow passage in which the mixed gas containing plural components flows and >=10 kg/Nm3 liq./gas ratio, plural steps of screening bodies 11 low in ventilation resistance (constitution substantially free from causing the hold up of absorbing liq. on either screen body 11, for example, meshlike body having >=50% perforation rate) are provided in the gas-liq. contacting device, and the regulation of the mixed gas such as boiler waste gas is executed, and simultaneously the absorbing liq. is sprayed from a spray nozzle 8 toward the screen bodies 11 to disperse the absorbing liq. The holding up of the absorbing liq. is prevented while achieving a prescribed desulfurization rate since absorbing liq. drop is renewed at the time when the mixed gas passes the screen bodies 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-liquid system for absorbing a specific component in a mixed gas, such as an absorption tower in a wet flue gas desulfurization unit for removing sulfur oxides in exhaust gas in a thermal power plant. It relates to a contact device.

[0002]

2. Description of the Related Art As a gas-liquid contact device for absorbing a specific component in a mixed gas, for example, a purification tower for purifying a gas produced by a chemical reaction is known. In the thermal power plant, the absorption tower, which is the main device of the wet flue gas desulfurization unit that removes sulfur oxides from the boiler exhaust gas, is a typical gas-liquid contact device. This is explained using a tower as an example.

[0003] As a treatment apparatus for removing sulfur oxides contained in combustion exhaust gas discharged from a boiler in a thermal power plant, a wet flue gas desulfurization apparatus using a limestone-gypsum method is widely used. This device is composed of an absorption tower equipped with a gas-liquid contacting device that absorbs sulfur oxides by bringing exhaust gas into contact with a slurry-like absorption liquid containing limestone and gypsum, and sulfur oxides in the absorption liquid absorbed by the absorption tower. Consists of several devices for finally recovering as gypsum.

[0004] Conventionally, as the type of absorption tower, a perforated plate tower, a packed tower, a spray tower and the like have been used. The perforated plate tower makes a large number of holes with a diameter of, for example, about 30 mm in a thin metal plate,
The ratio of the opening to the total area of the metal plate (opening ratio) is 3
A plurality of perforated plates of about 0% are provided in the absorption tower, the exhaust gas is raised from below the perforated plates, and the absorbing solution is caused to flow down from above the perforated plates to bring the gas and the absorbing solution into contact with each other, thereby absorbing the gas (sulfur oxide). Absorption).

[0005] The packed tower is provided with a packed bed filled with a large number of objects having a large surface area, for example, cylindrical or annular objects, in the absorption tower, the exhaust gas is raised from the lower part of the packed tower, and the absorbent is allowed to flow down from the upper part. Thus, the exhaust gas is brought into contact with the absorbing liquid to absorb the gas.

[0006] In the spray tower, a spray nozzle is installed in an absorption tower, and the exhaust gas and the absorbing liquid are brought into contact with each other by spraying / dispersing the absorbing liquid from the spray nozzle toward the exhaust gas flow, thereby performing gas absorption.

In recent years, there has been a strong demand for reduction in power generation cost and reduction in the installation area of power generation equipment, and designs have been made to reduce the size of desulfurization units, particularly to reduce the height or volume of absorption towers. Accordingly, the gas flow velocity in the absorption tower tends to increase. For this reason, the desulfurization unit must adopt a structure that is as simple as possible and a structure that increases the gas flow rate. However, a device that does not cause a significant increase in ventilation loss when the gas flow rate is increased is desired. It is rare.

The desulfurization rate η (%), which is a performance index of the desulfurizer, is defined as Cp, the concentration of sulfur oxides in the untreated exhaust gas at the inlet of the absorption tower, and Ct as the sulfur oxide concentration in the exhaust gas at the outlet of the absorption tower. Then, it is represented by the following equation (1).

Η = (Cp−Ct) / Cp × 100 (%) (1) The desulfurization rate in the same absorption tower is determined by the ratio of the absorption liquid amount L (kg) to the gas amount G (Nm ³ ), L / G. (Liquid-gas ratio). When the absorption liquid flow rate is increased at a certain gas flow rate, that is, when the liquid / gas ratio L / G is increased, the desulfurization rate is improved. Conversely, if the absorption liquid flow rate is reduced, that is, if the liquid / gas ratio L / G is reduced, the desulfurization rate decreases.

[0010] The sulfur oxide concentration Cp in the untreated exhaust gas is:
The sulfur oxide concentration Ct in the treated exhaust gas fluctuates depending on the sulfur content in the fuel used, and the upper limit of the sulfur oxide concentration Ct in the treated exhaust gas is set in advance. It depends on the concentration Cp, and the liquid / gas ratio L /
You need to drive in G.

Comparing the above three types of absorption towers, the perforated plate tower and the packed tower have a complicated structure but a large gas-liquid contact area, and it is easy to obtain a high desulfurization rate even at a relatively low liquid / gas ratio L / G. Has features. However, both have large ventilation losses, so they can be said to be suitable for plants with low gas flow rates.

On the other hand, the spray tower has a feature that the structure is simple and the ventilation loss is small as compared with other absorption towers. In the conventional desulfurization apparatus, the gas flow rate is a maximum of about 3 m / s, and the liquid / gas ratio L / G is at least. It is designed to be 10 or more.

Since the ventilation loss increases almost in proportion to the square of the gas flow velocity, the perforated plate tower and the packed tower increase the ventilation loss by increasing the gas flow velocity as compared with the spray tower as described above. It is disadvantageous. Therefore, from the viewpoint of minimizing the increase in ventilation loss, the spray tower is the most advantageous among the above three types of absorption towers.

FIG. 12 is a schematic view showing a main part of a vertical absorption tower of a spray tower type in a conventional wet flue gas desulfurization apparatus using the limestone-gypsum method. This absorption tower has an inlet duct 2 for untreated exhaust gas 1 on its side wall, a circulation tank 4 at the bottom of the tower, and a multi-stage spray header 7 at the top of the tower and a number of spray nozzles 8 at each header 7. Is provided. The absorbing liquid sprayed from the spray nozzle 8 comes into gas-liquid contact with the exhaust gas, absorbs sulfur oxides in the exhaust gas, and falls into the circulation tank 4. The treated exhaust gas 9 from which the sulfur oxides have been removed and which has been purified is discharged from an outlet duct 10.

The spray tower type absorption tower as shown in FIG. 12 has a feature that the structure is simple and the ventilation loss is small, but the flow of the exhaust gas introduced from the inlet duct 2 is evenly distributed over the cross section of the absorption tower. Further, there is a problem that it is difficult to perform the gas-liquid contact operation by uniformly dispersing the absorbing liquid sprayed from the spray nozzle 8.

As described above, since the desulfurization rate depends on the liquid / gas ratio L / G, in order to achieve a predetermined desulfurization rate, the higher the gas flow rate becomes in the absorption tower, the more the spray amount of the absorption liquid becomes. High density is required.

In the case of increasing the gas flow rate by increasing the size of a conventional spray tower type absorption tower having a gas flow rate of 3 m / s at the maximum (in recent years, such a demand is high), specifically 5 m / s
In order to achieve a predetermined desulfurization rate when the gas flow rate is not less than s, the operation is performed at a liquid / gas ratio of L / G = 10. It is necessary to increase the density.

However, in the gas-liquid contacting apparatus, particularly in the case where the gas flow direction changes, a short path region is generated due to the uneven gas flow, so that the gas-liquid contact becomes poor, and the desulfurization rate may decrease. Thus, the effect becomes greater as the gas flow velocity is increased and the spray amount of the absorbing liquid is increased.

[0019]

Therefore, for the purpose of uniformly distributing the flow of the exhaust gas 1 introduced from the inlet duct 2 of the absorption tower over the entire cross section of the absorption tower, and then bringing it into gas-liquid contact with the absorbing liquid, for example, FIG. As shown in FIG. 12, a perforated plate 15 having an aperture ratio of about 30% may be provided in the section of the absorption tower immediately above the gas inlet duct of the vertical absorption tower.

In place of the perforated plate 15 shown in FIG.
Japanese Patent Application Laid-Open No. 7-100324 describes a gas-liquid contact device in which a liquid sprayed from a spray nozzle is brought into contact with a mixed gas that has passed through a mesh to efficiently absorb gas.

The perforated plate has a large ventilation loss as compared with the mesh body, and particularly when the flow rate of the absorbing liquid is increased, a so-called hold-up state in which droplets stay on the perforated plate tends to occur. In addition, if the aperture ratio of the mesh body is not properly selected, the hold-up occurs. The invention described in Japanese Patent Application Laid-Open No. 7-100324, in which the mesh is provided, is considered to be a device having good gas-liquid contact efficiency. No consideration is given to the up-up, and there is no suggestion in the prior art relating to other spray type gas-liquid contact devices.

FIG. 4 schematically shows the relationship between the gas flow rate and the liquid / gas ratio L / G and the ventilation loss. Under the same liquid / gas ratio L / G conditions, the ventilation loss is equal to the gas flow rate. Increases in proportion to approximately the square of. Under the same gas flow rate condition, the ventilation loss increases almost in proportion to the increase amount of the liquid / gas ratio L / G, but when the liquid / gas ratio L / G is increased to a predetermined value or more, hold-up occurs, and the ventilation loss Increases rapidly.
In FIG. 4, the state in which this hold-up occurs is represented by H.

The higher the gas flow rate, the more likely the hold-up occurs even at a low liquid / gas ratio L / G. For example, a gas flow rate of a maximum of about 2 to 3 m / s based on the superficial superficial velocity has been increased.
Recently at least 5m / s, at most 10m / s
s or more.

In the conventional perforated plate 15 (FIG. 12), the absorbing liquid droplets are apt to stay, so that under such conditions, hold-up easily occurs and extremely large ventilation power is required. On the other hand, if an attempt is made to operate at a liquid / gas ratio L / G at which no hold-up occurs in order to suppress the ventilation power, a sufficient desulfurization rate cannot be achieved.

Therefore, in the conventional technique, it was not possible to simultaneously increase the gas flow velocity in the absorption tower of the above-mentioned wet flue gas desulfurization apparatus and suppress the increase in ventilation loss.

An object of the present invention is to provide a gas-liquid contact device which solves the above-mentioned problems of the prior art and simultaneously solves the problems of increasing the gas flow rate and suppressing the increase in ventilation loss.

[0027]

An object of the present invention is to spray a gas absorbing solution onto a gas mixture from at least one stage spray nozzle into a gas flow path through which a gas mixture containing a plurality of components flows. Is provided in the gas-liquid contact region where the specific component is absorbed by the absorbent, the gas flow rate in the gas-liquid contact region under the maximum load condition is 5 m / s or more, and the liquid / gas ratio (kg / Nm ³ ) is 10 In the gas-liquid contact device operating at a high gas flow rate and a high liquid density as described above, the spray nozzle and the mixed gas flow are arranged in the gas-liquid contact region in the spraying direction of the absorbing liquid from the spray nozzle. A plurality of screens are provided, and the gas-liquid contact area is achieved by a gas-liquid contact device configured to substantially not hold up the absorbing liquid on any of the plurality of screens.

In the present invention, a plurality of screens having low ventilation resistance are installed in the gas-liquid contacting device to rectify the mixed gas, and at the same time, the absorbing liquid is sprayed from the spray nozzle toward the screen to absorb the absorbing liquid. Is dispersed, and when the mixed gas passes through the screen body, the absorbing droplets are renewed.For example, it is possible to prevent the absorbing liquid from being held up on the screen body while achieving a predetermined desulfurization rate. it can.

In the gas-liquid contact device of the present invention, one or more screens provided in the gas-liquid contact area and one spray nozzle are combined into one unit, and the unit is formed of the same mixed gas. By adopting a configuration in which a plurality of liquids are stored in series in the flow direction, the chance of contact between the absorbing liquid and the mixed gas can be increased, and the mixed gas can be prevented from bypassing the gas-liquid contact region.

The screen body of the present invention refers to, for example, a configuration in which linear bodies having a diameter of a fraction of several millimeters to several millimeters are arranged in parallel with each other and a configuration in which the linear bodies cross each other.
Further, the configuration of the gas-liquid contact region that does not substantially cause the hold-up of the absorbing liquid on any one of the plurality of screen bodies of the present invention means, for example, that the aperture ratio of each screen body is 50% or more. It is to be.

In the gas-liquid contact device of the present invention, the gas flow direction is reversed from the gas flow direction in the gas flow path on the exhaust gas introduction side from the middle of the mixed gas flow path. At least one stage spray nozzle is disposed in the gas flow path, and a gas-liquid contact region is provided in which a plurality of screens are disposed facing the mixed gas flow in the direction of spraying the absorbing liquid from the spray nozzle. You can also.

When the high-speed gas flow is reversed in the gas-liquid contact device having this configuration, the gas flow becomes uneven and the gas-liquid contact is likely to be poor. Thereby, good gas-liquid contact can be achieved.

As the gas flow rate increases, the volume inside the absorption tower decreases, while the density at which the absorbing liquid is sprayed increases, so that the ventilation resistance of the spray header 7 and the spray nozzle 8 installed in the absorption tower also decreases. Is relatively large compared to the case of Therefore, the gas-liquid contact device of the present invention,
If a part or all of the spray header and the spray nozzle is arranged outside the wall constituting the gas flow path and the spray nozzle of the spray nozzle is provided inside the wall constituting the gas flow path, even if the gas flow rate is increased, , The spray header 7 and the spray nozzle 8 can be prevented from becoming a gas flow resistor.

The gas-liquid contact device of the present invention is used not only for the desulfurization device in the boiler exhaust gas, but also for the removal of harmful and unnecessary components in the mixed gas, the recovery of useful components, the recovery and purification of gases produced by chemical reactions, and the like. Can be

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention are described below. A spray tower type absorption tower, which is a main apparatus of a wet flue gas desulfurization apparatus for removing sulfur oxides from boiler exhaust gas, is a typical gas-liquid contactor. An example will be described with reference to the drawings.

FIG. 1 shows an outline of a main part of a vertical absorption tower of a wet type flue gas desulfurization apparatus using a limestone-gypsum method. In addition, although illustration is omitted here, in an actual desulfurization apparatus, equipment for supplying limestone contained in the absorbing solution is started,
Equipment, piping, and equipment for oxidation of the reaction product of the absorbed sulfur oxide and limestone and dehydration of the finally formed gypsum are attached.

As with the conventional absorption tower shown in FIG. 12, the absorption tower shown in FIG.
A circulation tank 4, a spray header 7, a spray nozzle 8, an outlet duct 10, and the like are provided. In the absorption tower shown in FIG. 1, the perforated plate 15 provided in the conventional absorption tower shown in FIG. 12 is not used, and the absorption liquid from each spray nozzle 8 downstream of the exhaust gas 1 introduction portion of the inlet duct 2 in the tower is used. It is characterized in that the screen body 11 is provided in the spray area of (limestone-gypsum slurry). The screen body 11 is provided in a plurality of stages in the spray area of the absorbing liquid of each spray nozzle 8.

The untreated exhaust gas 1 is introduced from the inlet duct 2 into the absorption tower, the direction of the gas flow introduced into the absorption tower is changed upward, and the distribution of the flow velocity in the tower cross section tends to vary. However, since the exhaust gas 1 introduced into the absorption tower strikes the screen body 11 and is rectified, the exhaust gas 1 rises in the tower, and as the gas passes through the screen body 11, the gas flow becomes uniform.

The absorbent 5 is supplied from the circulation tank 4 to the circulation pump 6
And sprayed from a large number of spray nozzles 8 attached to the spray header 7 toward the exhaust gas 1, and the absorbing liquid and the rising exhaust gas 1 come into countercurrent contact, so that the sulfur oxides in the exhaust gas 1 become the absorbing liquid. Absorbed and removed,
The gas is discharged from the outlet duct 10 to the outside of the absorption tower as the processing gas 9.

Here, in the prior art shown in FIG. 12, there is nothing to renew the absorbing droplets by collision except for the spray header 7 or the spray nozzle 8 until reaching the perforated plate 15, but in the absorbing tower shown in FIG. Since the absorbing liquid is sprayed toward the screen body 11 from the spray nozzle 8 in each gas-liquid contact area, the absorbing liquid droplets are updated, and the gas-liquid contact efficiency increases. As described above, in the absorption tower of the present invention, the flow of the exhaust gas 1 introduced from the inlet duct 2 is rectified, and at the same time, the absorbing liquid droplets collide with the screen body 11 and are renewed to perform gas-liquid contact. is there.

FIG. 3 shows the relationship between the number of stages of perforated plates and screens per spray nozzle installed in an absorption tower and the desulfurization rate determined in a laboratory.

The screen used in this experiment is, for example, a stainless wire having a circular cross section of 0.9 mm in diameter as shown in FIG.
Are arranged in parallel with each other at equal intervals as shown in FIG. 10, or are in a mesh shape alternately orthogonal as shown in FIG. 10, and the aperture ratio is about 70%. The perforated plate is an acrylic plate having an opening diameter of 8 mm and the opening ratio is 30%. Also,
The absorption tower had a vertical cylindrical shape, gas was introduced from the lower part, and the absorbing liquid was sprayed from the upper spray nozzle 8.

The desulfurization rate was improved as the number of perforated plates or screens inserted per spray nozzle was increased, and the desulfurization rates of the perforated plates and screens when four stages were inserted were almost equal. On the other hand, FIG. 5 schematically shows the relationship between the type of insert made of a perforated plate or a screen and the ventilation loss under a constant liquid / gas ratio of L / G. The same perforated plate and screen as those in the experiment of FIG. 3 were used, and four stages were inserted.

In the case of a perforated plate, during the process of gradually increasing the gas flow rate and the liquid / gas ratio L / G, hold-up of the absorbing liquid occurs from the lowermost stage, so that the ventilation loss sharply increases.
Under the conditions of 1.5 m / s and liquid gas L / G = 10, hold-up was observed in all stages. Compared to the perforated plate, the screen body having a small ventilation loss in the empty tower has a gas flow rate of 5 m /
In addition, the hold-up did not occur at all stages even when the liquid / gas ratio L / G was increased to 10.

The pressure loss is the lowest under the condition without an insert such as a screen or a perforated plate, but L / G is required to increase the desulfurization rate to the same level as when the perforated plate or the screen is inserted. Therefore, the power of the circulation pump 6 (FIG. 1) is significantly increased.

The experimental results shown in FIGS. 3 and 5 indicate that the following can be realized by installing a plurality of screens having a larger aperture ratio than the perforated plate in the absorption tower. .

That is, firstly, the gas rectification effect of the gas produced by the screen body or the renewal of the absorbed droplets colliding with the screen body improves the gas-liquid contact efficiency, and the desulfurization rate equivalent to that of the perforated plate can be achieved. Secondly, since the hold-up of the absorbing liquid does not occur up to the conditions of the high gas flow rate and the high liquid gas ratio L / G, the increase in the ventilation loss with respect to the ventilation loss when the insert is not used can be suppressed low.

The structural elements of the screen body that influence the hold-up of the absorbing liquid include the overall shape of the screen body (such as the crossing state of the screen materials constituting the screen body), the aperture ratio, and the adjacent screen materials. , The interval (pitch) of each step of the screen body, the width of each screen material (the length in the direction orthogonal to the gas flow), the cross-sectional shape of the screen material, and the like.

Hereinafter, an appropriate combination of these elements will be described. First, regarding the overall shape of the screen body, in the above-described experiment, a mesh-like shape in which stainless wires having a circular cross section were alternately orthogonally arranged at regular intervals was used, but the shape of the screen body according to the present invention was used. Is not limited to this. The most unlikely occurrence of hold-up in the overall shape of the screen body is a plurality of screen materials shown in FIG. 7 arranged in parallel with each other, and hold-up is likely to occur as screen materials intersecting with this are added. Become.

This phenomenon is because, when a plurality of screen materials are crossed, the distance between the screen materials is reduced as approaching the intersection, and the liquid droplets tend to stay. Therefore, from the viewpoint of preventing the occurrence of hold-up, it is desirable to reduce the number of intersections between the screen materials, and when they intersect, it is desirable to increase the angle between the screen materials. For example, it is best to make two screen materials orthogonal.

Next, the aperture ratio of the screen body will be described. The aperture ratio of the screen body in each stage needs to be set to a larger value as the device is operated under the condition of a high gas flow rate or a high liquid gas ratio L / G. The screen body used in the experiments shown in FIGS. 3 and 5 has an aperture ratio of about 70%. Even if the aperture ratio is the same, for example, when the interval (span) between adjacent screen materials is small, the absorbing liquid Due to the surface tension of the liquid crystal, droplets can be cross-linked between adjacent screen materials, and a situation in which hold-up is likely to be caused. On the other hand, when the span is considerably larger than the diameter of the absorbing droplet, it is difficult to hold up, but the effect of updating the droplet due to collision is reduced.

Therefore, it can be said that the lower limit of the aperture ratio is the minimum value that can be implemented when the combination of other elements is the condition in which the hold-up hardly occurs. On the other hand, the upper limit of the aperture ratio is, on the contrary, the aperture ratio when other elements are most likely to cause hold-up, or the strength requirement of the screen material affected by the width of the screen material. It is an aperture ratio representing a practicable limit required based on (including abrasion resistance).

However, in the case of a so-called general net composed of a linear body having a diameter of a fraction of a millimeter to several millimeters as described above, the aperture ratio of 50% or more is appropriate.

Next, the interval (span) between adjacent screen materials will be described.

The interval (span) between adjacent screen materials in the same screen is determined by the following criteria.
That is, as described above, the lower limit of the span needs to be such that the surface tension of the absorbing liquid causes the cross-linking of the droplets between the adjacent screen materials so that the hold-up does not easily occur. Although it depends on the operating conditions and the diameter of the scattered droplets, it is empirically determined that the span is preferably 5 mm or more.

The span can be made smaller as the number of intersections of the screen materials is smaller. Regarding the screen step interval (pitch), if the pitch is too close, the re-dispersion of droplets is likely to be hindered, and it is difficult to make the gas flow uniform, so the lower limit of the pitch is such a problem. Must not occur.

Although the pitch is affected by the length or shape of the cross section of the screen material, as a result of repeated experiments, the width of the screen material (the length in the direction perpendicular to the gas flow) is Wx, and the length of the cross section (gas Wz)
It was found that it was desirable to set the pitch P so that P ≧ 500 × Wx / Wz (mm).

When the screen members constituting the screen member viewed from the spray nozzle direction do not overlap each other, that is, when the screen members are arranged in a staggered manner, the pitch P can be reduced under the above-described conditions. The upper limit of the pitch is not particularly limited, but it is necessary to consider the layout of the absorption tower, the dispersion of the absorbing liquid, the effect of renewing the droplet by collision, and the like.

Looking at the width (length in the direction perpendicular to the gas flow) and the cross-sectional length (length in the gas flow direction) of the screen material, the lower limit of the width and the cross-sectional length of the screen material is as follows.
It is determined from the strength or abrasion resistance of the screen material. Although it depends on the material, for example, in the case of a stainless steel wire, it is preferably 0.5 mm or more. The upper limit is not particularly limited, but it is necessary to take into account the renewal of the droplet due to collision and the diameter of the droplet re-scattered.

Next, the cross-sectional shape of the screen material will be described. In this embodiment, the cross-sectional shape of the screen material is circular, but various shapes such as an ellipse, a square, and an airfoil can be applied as described above. FIG. 6 shows a cross-sectional shape of the screen material.

(1) shows a circular or elliptical cross section. Since a circular one can be formed using a general wire, it can be manufactured relatively easily and has a shape in which the hold-up of the absorbing liquid is hard to occur. . Elliptical ones are more preferred because they have lower resistance than circular ones.

(2) is an example of a rectangular cross section, which has a higher resistance than other shapes, easily causes hold-up of the absorbing liquid, and increases ventilation loss. On the other hand, there is an advantage that processing can be easily performed, for example, by punching a thin plate.

(3) has a wavy cross section, and has an advantage that a gas-liquid contact area can be increased.

(4) has a wing-shaped cross section, has a high gas rectification effect, has the lowest ventilation loss in the air column,
Suitable for equipment with high gas flow rate.

Regarding each cross-sectional shape of the above-mentioned screen material,
The smaller the radius of each tip is, the smaller the diameter of the droplet when the attached droplet re-scatters, and the effect of improving the gas-liquid contact appears.

FIG. 7 shows a specific structure of the screen body 11 constructed in consideration of the above points. The overall shape having the following dimensions is such that a screen material 12 having a circular cross section is arranged in parallel, Are enclosed by an outer frame 14 as one unit.

Opening ratio: 80% (per panel) Interval between adjacent screen materials (span): 12 mm Width of screen material (length in the direction perpendicular to gas flow):
3 mm FIG. 8 shows an outline of a gas-liquid contact device in which the screen body 11 is provided in a plurality of stages in the direction of spraying the absorbing liquid from the plurality of spray nozzles 8 of the spray header 7.

Each stage of the screen body 11 has the above-mentioned panels 13 arranged on a support beam (beam) plane. Therefore, the aperture ratio of each step of the screen body 11 needs to subtract the amount of the support beam.

When each screen body 11 is formed of a linear body arranged in parallel to each other as shown in FIG. 7, each stage of each screen body 11 is formed of a screen material viewed from the spray nozzle 8 side. As shown in FIG. 9, for example, the arrangement is desirably arranged at such a position that the linear bodies intersect each other at an angle of 60 ° in three stages.

Screen step interval: pitch is 500 m
m. Hereinafter, an example in which the screen body 11 is applied to each absorption tower will be described.

In the gas-liquid contact device according to the embodiment of the present invention shown in FIG. 1, the screen body 11 exerts a rectifying action. As the exhaust gas 1 rises and passes through the screen body 11, the gas flow becomes uniform. The absorption liquid 5 (limestone-gypsum slurry) is pumped from the circulation tank 4 to the spray header 7 by using the circulation pump 6, is sprayed toward the exhaust gas 1 from a number of spray nozzles 8 attached to the spray header 7, and rises with the absorption liquid. When the exhaust gas 1 comes into countercurrent contact, sulfur oxides in the exhaust gas 1 are absorbed and removed by the absorbing liquid.

Here, in the prior art, the perforated plate 15 (FIG. 1)
Until the process reaches 2), there is nothing other than the spray header 7 or the spray nozzle 8 to renew the absorbing droplets by collision, but in the present invention, the absorbing liquid is directed to the screen body 11 from the spray nozzle 8 of each gas-liquid contact device. As the liquid is sprayed, the absorbing droplets are renewed, and the gas-liquid contact efficiency is increased. in this way,
In the apparatus shown in FIG. 1, the flow of the exhaust gas 1 introduced from the inlet duct 2 is rectified, and at the same time, the absorbing liquid droplets collide with the screen body 11 and are renewed to perform gas-liquid contact.

In the embodiment shown in FIG. 2, a screen body 11 which satisfies the above-mentioned condition in which the hold-up does not occur is inserted into the absorption tower where the inside of the absorption tower is partitioned and the gas flow is reversed.

When the high-speed gas flow is reversed in the absorption tower, the gas flow becomes non-uniform and the gas-liquid contact is likely to be poor. By doing so, good gas-liquid contact can be achieved.

In the example shown in FIG. 2, the spray nozzle 8 is arranged so that the spray absorbing liquid from the spray nozzle 8 is in parallel with the exhaust gas on the exhaust gas inlet side, and the spray absorbing liquid is in parallel with the exhaust gas on the exhaust gas outlet side. However, depending on the flow rate of the exhaust gas, the size of the screen body 11, and the like, the direction of the countercurrent or the parallel flow may be determined on the exhaust gas inlet side or the exhaust gas outlet side. If the spray nozzle 8 is arranged so that the spray absorption liquid is in parallel with the exhaust gas, hold-up is less likely to occur than in the case of the counter-current arrangement. Therefore, an appropriate arrangement is determined in consideration of this point. It is important.

As the gas flow rate increases, the internal volume of the absorption tower decreases, while the density at which the absorbent is sprayed increases. Therefore, the ventilation resistance of the spray header 7 and the spray nozzle 8 installed in the absorption tower also decreases. Is relatively large compared to the case of Therefore, as shown in FIG. 11, a part or all of the spray header 7 and the spray nozzle 8 are arranged outside the absorption tower, and the spray nozzle of the spray nozzle 8 is made to face the inside of the absorption tower. 7 and the spray nozzle 8 can be prevented from becoming a gas flow resistor.

[0077]

According to the present invention having the above-described structure, it is possible to simultaneously solve the problems of increasing the gas flow rate and suppressing an increase in ventilation loss, and to achieve a predetermined gas-liquid contact efficiency. Meanwhile, it is possible to provide a gas-liquid contact device that does not cause hold-up.

[Brief description of the drawings]

FIG. 1 schematically shows an absorption tower according to an embodiment of the present invention.

FIG. 2 shows a configuration of an absorption tower according to an embodiment of the present invention.

FIG. 3 shows the relationship between the number of perforated plates and screens installed in an absorption tower and the desulfurization rate obtained experimentally.

FIG. 4 shows a relationship between a gas flow velocity, L / G (liquid / gas ratio), and ventilation loss.

FIG. 5 shows the relationship between the type of insert and ventilation loss under certain L / G conditions.

FIG. 6 shows an embodiment of a cross-sectional shape of a screen material which is a component of the present invention.

FIG. 7 shows a configuration of a screen body (panel) according to the present invention.

FIG. 8 shows a configuration of a gas-liquid contact device according to the present invention.

FIG. 9 shows a configuration of a screen body made of a three-stage linear body according to the present invention as viewed from above.

FIG. 10 shows a configuration of a screen body made of a mesh body according to the present invention.

FIG. 11 schematically shows an absorption tower according to an embodiment of the present invention.

FIG. 12 shows an example of a configuration of an absorption tower according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Untreated waste gas 2 Inlet duct 3 Absorption tower 4 Circulation tank 5 Absorbing liquid 6 Circulation pump 7 Spray header 8 Spray nozzle 9 Treated exhaust gas 10 Outlet duct 11 Screen body 12 Screen material 13 Panel 14 Outer frame 15 Perforated plate

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[Procedure amendment]

[Submission date] June 23, 1999 (1999.6.2
3)

[Procedure amendment 1]

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[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hirofumi Yoshikawa 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Inside Kure Research Laboratory (72) Inventor Narito Takamoto 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Stock F-term in the Kure Research Laboratories (reference) 4D002 AA02 AC01 BA02 CA01 CA20 DA05 DA16 EA03 FA03 GA01 GB01 GB06 GB20 HA03 4D020 AA06 BA02 BA09 BB05 BC06 CB24 CB25 CB27 CC04 CC07 DA03 DB13

Claims (6)

[Claims] A gas-liquid for spraying a gas absorbing liquid onto a mixed gas from at least one stage spray nozzle into a gas flow path through which a mixed gas containing a plurality of components flows, and absorbing a specific component in the mixed gas into the absorbing liquid. A contact area is provided, and a gas flow rate in the gas-liquid contact area in a maximum load state is 5 m / s or more, and a liquid / gas ratio (kg / Nm ³ ) is 10 or more. In the gas-liquid contacting device to be operated, the gas-liquid contact region is provided with a plurality of screens arranged in the spraying direction of the absorbing liquid from the spray nozzle so as to face the mixed gas flow. A gas-liquid contact device, wherein substantially no hold-up of the absorbing liquid occurs on any of the screen members. 2. A gas flow path in which the direction of gas flow is reversed from the gas flow direction in the gas flow path on the exhaust gas introduction side from the middle of the mixed gas flow path, and the gas-liquid contact area is provided in each gas flow path. The gas-liquid contact device according to claim 1, further comprising: 3. A plurality of screens provided in the gas-liquid contact region, wherein one unit composed of a combination of at least one screen and one spray nozzle is connected in series in the flow direction of the same mixed gas. The gas-liquid contact device according to claim 1, wherein the gas-liquid contact device is configured to be housed. 4. A structure wherein substantially no hold-up of the absorbing liquid occurs on any of the screen bodies by setting the aperture ratio of each screen body to 50% or more. 4. The gas-liquid contact device according to any one of claims 1 to 3. 5. A spray nozzle of a spray nozzle, wherein a part or all of a spray header and a spray nozzle are arranged outside a wall constituting a gas flow path, and a spray nozzle of the spray nozzle is provided inside a wall constituting a gas flow path. Item 5. The gas-liquid contact device according to any one of Items 1 to 4. 6. A gas-liquid contact device according to any one of claims 1 to 5, wherein the gas-liquid contact device is an absorption tower that absorbs and removes a sulfur oxide contained in a mixed gas by spraying an absorbent solution comprising a limestone-containing slurry. A wet-type flue gas desulfurization device.