JP2001198430A - Gas-liquid contact method and gas-liquid contact apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of a gas-liquid contact apparatus for bringing a liquid to be treated absorbing a target substance in gas to be treated into contact with the gas to be treated and a related machinery thereof. SOLUTION: A contraction part (a throttle part wherein a plurality of attachments installed inside such as flat plates or restriction matters are arranged in a gas-liquid contact apparatus in order to narrow the cross-sectional area in the horizontal direction of an absorbing tower) generating a contraction in the flow of gas to be treated is provided in the absorbing tower of the gas- liquid contact apparatus for bringing a liquid to be treated absorbing a target substance in gas to be treated into contact with the gas to be treated and is constituted so that the liquid to be treated and the gas to be treated flow as a gas-liquid mixed stream. The liquid to be treated flowing through the contraction part as the gas-liquid mixed stream is divided by the fluid force of the gas to be treated and the articulation of the liquid to be treated is accelerated to absorb the target substance in the gas to be treated by the liquid to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel gas-liquid contacting device for bringing a gas to be treated into contact with a liquid to be treated.
In particular, it is a gas-liquid contact device suitable for desulfurization equipment that removes sulfur oxides from the combustion exhaust gas, as a device for treating large-volume combustion exhaust gas discharged from a thermal power generation wheeler, and also reduces power consumption during operation. Low wet flue gas desulfurization apparatus and method.

[0002]

2. Description of the Related Art The amount of combustion exhaust gas generated from the largest coal-fired power generation boiler having a power generation output of 1,000,000 kW is as high as 3.3 million cubic meters per unit time. In order to detoxify this large-volume flue gas, the exhaust gas purified from the chimney using a comprehensive smoke exhaust treatment system that combines elemental equipment consisting of dust removal, denitration, desulfurization, and gas-gas heat exchangers. It is being released to the atmosphere.

[0003] As a desulfurization apparatus for removing sulfur oxides from a gas to be treated, which is used in an integrated flue gas treatment system for environmental protection, a wet limestone / gypsum method is mainly used. In the wet limestone / gypsum method, a limestone slurry is brought into direct contact with a gas to be treated, and sulfur oxides are absorbed and removed from combustion exhaust gas. The sulfur oxides absorbed in the liquid to be treated are finally recovered as stable dihydrate gypsum.

Various types of gas-liquid contacting devices have been proposed for the wet limestone / gypsum method. A typical example is a method in which a liquid to be treated is mechanically applied with a shearing force at a spray nozzle portion, atomized by atomization, and the obtained droplets are brought into contact with combustion exhaust gas.

[0005] The amount of combustion exhaust gas discharged from a 1000 MW-scale thermal power plant requires an exhaust gas treatment of about 3.3 million cubic meters per unit time. One equipped with two absorption towers was used. However, recently, technology development for increasing the gas flow velocity in the absorption tower has been carried out, and 1
It has become possible to achieve compactification in which the entire amount of the gas to be treated on the 000 MW scale is treated by one absorption tower.

Further, in order to promote the downsizing of the absorption tower, it is conceivable to further increase the gas flow velocity in the absorption tower. In this case, the influence on the desulfurization performance, the effect of ventilation loss, etc. will be clarified. We have to go.

[0007] In particular, there is a concern that an increase in ventilation loss due to an increase in the gas flow rate will increase the power consumption of a blower required to convey a large amount of gas to be treated and increase the operating cost of the desulfurization unit. ing. That is, when the gas flow velocity in the absorption tower increases, the ventilation loss increases, which causes an increase in the power consumption of the blower for the gas to be treated.

On the other hand, in a thermal power plant or the like, a boiler in which the amount of generated power known as daily load change is adjusted is operated. In this daily load change operation, since the operation of changing the load amount in the boiler is performed, the amount of combustion exhaust gas and the concentration of sulfurous acid in the liquid to be treated generated in the exhaust gas treatment change. Therefore, it is necessary to operate the desulfurization device according to the power generation load change amount.

In the operation of a desulfurization apparatus based on the wet limestone / gypsum method, the amount of contact liquid to be treated per unit gas to be treated is adjusted according to the amount of gas to be treated introduced into the absorption tower and the concentration of sulfur oxides. Is being adjusted. The method of adjusting the amount of the liquid to be processed differs depending on the configuration of the gas-liquid contact device.

For example, in the method described in Japanese Patent Application Laid-Open No. Hei 10-235142, a plurality of circulation pumps are installed in order to adjust the amount of liquid to be conveyed to the gas-liquid contact device. The number of circulating pumps to be controlled has been controlled. With this method, when the boiler is under low load,
Energy saving operation can be performed in which the number of operating circulation pumps is reduced and the amount of the liquid to be processed conveyed to the gas-liquid contact device is reduced.

However, most of the desulfurization apparatuses based on the wet limestone / gypsum method contain solid gypsum of nearly 20% in the liquid to be treated. At the time of shutdown, it is necessary to perform operations to clean the pump and piping system. In particular, the circulation pump number control operation method is employed in a desulfurization apparatus of a type in which a liquid to be treated is sprayed against a gas to be treated.

The spray-type desulfurization device is a gas-liquid contact device for treating a large amount of combustion exhaust gas. The spray-type gas-liquid contact device is easy to manufacture, has a relatively simple structure, and has a ventilation structure. There are many features that can reduce the loss and at the same time, highly remove the dust in the gas to be treated. However, the spray-type gas-liquid contact device has disadvantages such as a large power consumption for atomizing the liquid to be treated.

[0013] Further, when the gas flow velocity in the absorption tower is increased, the ventilation loss is increased, which causes an increase in the power consumption of the gas blower to be treated.

[0014]

In the conventional desulfurization apparatus using the wet limestone / gypsum method, the gas flow rate in the absorption tower is increased in order to increase the desulfurization rate with the increase in the amount of gas to be treated. In order to satisfy the demand for reducing equipment costs, the absorption tower is downsized.

However, when the absorption tower is miniaturized, the gas flow velocity in the tower is increased, the ventilation loss is increased, and the power of the blower for conveying a large amount of gas to be treated is increased.

Therefore, in order to reduce the size of the absorption tower, the construction of the absorption tower that does not increase the ventilation loss and the reduction of the power of the equipment that consumes a large amount of power around the desulfurizer may compensate for the increase in the power of the blower. Will be needed.

An object of the present invention is to reduce the size of a gas-liquid contacting device for bringing a gas to be treated into contact with a gas to be treated and a gas to be treated which absorbs a target component in the gas to be treated, thereby increasing the gas flow rate in the device. However, it is an object of the present invention to increase the efficiency of purifying the gas to be treated without increasing the ventilation loss.

Another object of the present invention is to provide a gas-liquid contacting device for bringing a liquid to be treated into gas-liquid contact with a liquid to be treated which absorbs a target component in the gas to be treated, when the flow rate of the gas to be treated changes on a daily basis. Even in this case, instead of the conventional method of controlling the number of pumps for supplying the liquid to be processed to the gas-liquid contact device, a variable-speed circulating pump capable of adjusting the transport amount of the liquid to be processed with one pump is used. It is to provide a gas-liquid contact device capable of performing the above-mentioned.

A further object of the present invention is to reduce the power consumption of a gas-liquid contacting device for bringing a gas to be treated into contact with a gas to be treated and a gas to be treated, which absorbs a target component in the exhaust gas to be treated, and related equipment. is there.

[0020]

One of the solutions to the above-mentioned problems of the present invention is to provide a gas-liquid contacting device for contacting a gas to be treated with a liquid to be treated which absorbs a target component in an exhaust gas to be treated. A contraction section (throttle section) for causing a contraction in the flow of the gas to be treated is provided, and the liquid to be treated and the gas to be treated flow through the contraction section in a multiphase flow. The liquid to be treated flowing through the contraction part by this multiphase flow is split by the fluid force of the gas to be treated, thereby promoting the atomization of the liquid to be treated.

In order to form a contraction section in the absorption tower of the gas-liquid contacting device, an internal plate or a constrained member for restricting the flow of the gas to be treated and narrowing the horizontal cross-sectional area of the absorption tower is used. Install multiple objects.

The liquid to be treated flows down on the above-mentioned internal object, flows as a multiphase flow of the liquid to be treated and the gas to be treated in the contraction portion, and is caused by a large fluid force generated by the contraction of the gas to be treated which is rapidly formed. The liquid to be treated is divided and atomized.

If a gas flow contraction occurs in the absorption tower, the ventilation loss will increase. However, it is necessary to optimize the structure of the flow contraction taking these factors into consideration. According to the configuration of the present invention described above, the transport power of the pump, which is conventionally required for atomizing the liquid to be treated, can be greatly reduced.

Another object of the present invention is to prevent an increase in gas flow rate and an increase in ventilation loss due to downsizing of an absorption tower, thereby preventing an increase in power consumption. As one of the solutions, in the present invention, a novel gas-liquid contact device having a contraction part of a gas to be treated and a variable speed circulating pump for adjusting the number of rotations to control the transport amount of the liquid to be treated, etc. A configuration may also be adopted in which the processing liquid transport amount adjusting means is mounted, the processing liquid flowing down from the gas-liquid contact device is pumped up, and the processing liquid flows down again from above the gas-liquid contact device.

A desulfurization apparatus for removing sulfur oxides from combustion exhaust gas of a thermal power plant is easy to manufacture and has a relatively simple structure, can reduce ventilation loss, and at the same time, highly removes dust in a gas to be treated. The spray method that can be used is adopted. The spray method has many advantages, but the spray method also has disadvantages such as a large amount of power consumption for atomizing the liquid to be treated.

Therefore, the present invention employs the following novel gas-liquid contact device. That is, the gas-liquid contact device of the present invention provides an internal component that forms a contraction portion in the flow of the gas to be treated in the absorption tower to form a constricted portion. Performs a high-level mass transfer while flows in a gas-liquid two-phase flow.

In the treatment liquid spray method, mechanical power consumption is required to atomize the treatment liquid.
In the present invention, no power is required for atomizing the liquid to be treated.

Further, in order to perform a high mass transfer in the gas flow contraction part in the absorption tower of the present invention, the gas and the liquid to be treated flow in the gas contraction part in the gas-liquid two-phase flow state. In addition, the liquid to be treated is dispersed and split by the fluid force of the gas to be treated, so that the gas-liquid contact area is increased and the liquid-side interface of the liquid to be treated is actively renewed.

As described above, according to the present invention, in order to form a contraction zone in the gas to be treated flowing in the absorption tower, an internal component for restricting the flow of the gas to be treated is provided. In order to reduce the cross-sectional area of the gas flow crossing the flowing direction of the gas to be treated, the internal components are provided in a plurality of stages in the height direction of the absorption tower.

When a flat plate is used, it is desirable to install a plurality of flat plates inclined downward from the side wall surface of the absorption tower toward the center. In this case, it is desirable to adopt a configuration in which the liquid to be treated that has flowed down on the flat plate flows down on the flat plate and then flows down from the center of the absorption tower to the next lower flat plate.

Depending on the amount of gas to be treated, the flat plates may be installed in a tower in a plurality of stages in a staggered arrangement, for example, as one line, and may be installed in a plurality of lines in the tower.

The liquid to be treated forms a gas-liquid two-phase flow with the gas to be treated in the process of flowing from the upper plate to the lower plate, and gas dispersion and atomization of droplets occur to a high degree. Mass transfer can take place in a liquid two-phase flow. If the gas to be treated is a boiler exhaust gas, sulfur oxides in the exhaust gas are absorbed in a liquid to be treated (absorbing liquid) such as lime slurry.

Further, according to the present invention, a circulating pump for controlling the number of rotations to control the transport amount of the liquid to be treated is mounted, and the liquid to be treated which has flowed down from the absorption tower of the gas-liquid contacting device is pumped up and re-absorbed. A configuration may be adopted in which the liquid to be treated flows down from above.

With this configuration, for example, the flow rate of the combustion exhaust gas from the boiler for thermal power generation used as the gas to be treated according to the present invention,
The desulfurization performance can be kept constant even if the SO ₂ concentration in the exhaust gas changes greatly based on the change in boiler load.

When the liquid spraying method is adopted, a plurality of circulating pumps for circulating the absorbing liquid in the absorption tower are installed in response to a change in the flow rate of the gas to be processed occurring in the thermal power boiler. 2. Description of the Related Art Conventionally, a pump number control operation for adjusting the number of operating constant flow type circulation pumps in accordance with a boiler load change amount has been performed.

This method of controlling the number of pumps is a method of operating the number of pumps according to the boiler load. In this pump number control operation, if there is a stopped circulation pump, it is necessary to clean the inside of the pump so that the solids in the liquid to be processed do not settle during the stop and prepare for the next high-load operation. There is.

However, according to the present invention, a variable speed circulating pump capable of varying the flow rate is used in combination with a gas-liquid contact device having an absorption tower provided with a contraction section, so that the daily load change amount frequently generated in a boiler or the like is obtained. Can be easily handled.

Further, in the gas-liquid contact device of the present invention, no mechanical power is required for atomizing the liquid to be treated and the like, and the liquid to be treated is supplied from the upper part of the absorption tower onto a flat plate. The purpose of gas-liquid contact can be achieved.

In the conventional apparatus for spraying a liquid to be treated, it is necessary to always apply a constant back pressure to the spray nozzle to form a stable droplet distribution of the liquid to be treated and maintain a gas-liquid contact area. Therefore, there is a problem that it is difficult to control the liquid to be treated by the variable speed circulating pump because a constant back pressure needs to be applied to the spray nozzle. However, such a problem does not occur when the gas-liquid contact device of the present invention is used. .

The ability of the gas-liquid contacting device of the present invention to absorb components in the gas of the liquid to be treated (desulfurization performance, etc.) and the ventilation loss of the gas flow depend on the gas flow rate in the absorption tower of the gas-liquid contacting device and the flat plate etc. Greatly affected by the area of the opening (shrinkage portion) constrained by the internal components. The size of the opening (contracting portion) of the absorption tower constituting the gas-liquid contact device, the angle of inclination of the flat plate, which is an internal component, with respect to the horizontal, the number of stages of the flat plate, the interval between the flat plates, etc. Desulfurization performance and the ventilation loss are affected.

In particular, due to the flat plate structure, which is an internal component in the absorption tower constituting the gas-liquid contact device of the present invention, the ventilation loss in the absorption tower, which is used for desulfurization of boiler exhaust gas. For example, the gas absorption performance of the liquid to be treated, such as desulfurization performance, is affected. However, it has been clarified that a configuration in which a weir is provided on a flat plate is effective in enhancing the gas absorption performance, such as desulfurization performance.

Further, as a structure for blocking the liquid to be treated flowing down to the lower end of the flat plate, the flight distance L of the liquid to be treated is determined by the downward inclination angle θ with respect to the horizontal of the weir and the height H of the weir. The atomization of the liquid to be treated is greatly affected.

As a result of examining the configuration of the weir installed at the lower end of the flat plate, the liquid to be processed flowing down on the flat plate was atomized, and the mass transfer performance between the gas to be processed and the liquid to be processed (desulfurization performance, etc.) It is effective to provide a V-shaped groove weir or the like at the end of the flat plate in order to increase the height.

The gas-liquid contact device of the present invention is not only an absorption tower used for the limestone / gypsum wet desulfurization device, but also an ozone oxidation device, a sludge oxidation device, an oxygen supply device for aquaculture tanks,
The present invention can be applied to a mass transfer device in which air, oxygen, ozone, nitrogen gas, or the like is blown out into a liquid, such as an air diffusion tower or a nitrogen tank.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION A typical embodiment of a gas-liquid contact device of the present invention is a desulfurization device that absorbs sulfur oxides in combustion exhaust gas from a thermal power boiler and uses, for example, limestone slurry as an absorbent. The gas-liquid contacting device of the present invention will be described below with reference to FIG. 1, in which a desulfurization device including an absorption tower for bringing gas-liquid into contact with an absorbent composed of flue gas and limestone slurry and a circulation tank for storing the absorbent is used. .

The flue gas 3 from the thermal power boiler is denitrified, led to a gas / gas heat exchanger (not shown), cooled to a temperature of about 100 ° C., and then introduced into an electric precipitator for dedusting. The temperature of the exhausted flue gas 3 is about 10
It is introduced into the absorption tower 1 from the upper part of the absorption tower 1 shown in FIG.

When the combustion exhaust gas 3 comes into contact with the absorption liquid 7 composed of limestone slurry supplied from the pipe 2 in the absorption tower 1, the combustion exhaust gas 3 is adiabatically cooled and the sulfur oxides in the exhaust gas 3 are absorbed and removed. Inside the absorption tower 1 shown in FIG. 1, a plurality of inclined flat plates 61 to 64 are provided in order to restrict a gas flow and form a contraction part in the flow.

The absorption liquid 7 flowing down the absorption tower 1
Accumulates in the circulation tank 4 provided at the lower part of the tank. The absorbent 7 stored in the circulation tank 4 is conveyed to the upper part of the absorption tower 1 via the circulation pipe 12 by the circulation pump 10 and first supplied to the first flat plate 61. The absorbing liquid 7 supplied to the flat plate 61 flows down on the flat plate 61 and falls into the contraction portion. When the exhaust gas 3 is contracted and introduced into the contraction section at the same time as the absorption liquid 7, the contraction speed is increased, and the absorption liquid 7 is divided and atomized. As the circulation pump 10, a constant flow rate pump can be used, but it is desirable to use a variable speed type pump because controllability of the desulfurization rate is improved.

The absorption liquid 7 from the absorption liquid supply pipe 2 is supplied to each section from the dispersion pipe 2 for distribution to the flat plate 61. Therefore, atomization by swirling flow or the like is not performed at the nozzle tip as in the spray method.

At the end of the flat plate 61, a two-phase flow state of the exhaust gas 3 and the absorbing liquid 7 is formed, and the absorbing liquid 7 split and atomized by the fluid force falls sequentially on the lower flat plates 62 to 64. During that time, the sulfur oxides in the exhaust gas 3 are absorbed by the absorbing liquid 7, and the purified gas is discharged from the gas outlet 5 of the absorption tower 1.

On the other hand, the sulfurous acid gas in the gas to be treated 3 is absorbed by the absorbing solution 7 as sulfurous acid and stays in the circulating tank 4 as the absorbing solution 7 containing sulfite.
The absorption liquid 7 containing sulfite therein is oxidized by the air supplied from the air introduction pipe 9 to oxidize the entire sulfite to form sulfuric acid.

The produced sulfuric acid undergoes a neutralization reaction with the limestone supplied from the line 36, and is finally recovered as solid gypsum. At this time, by stirring the absorbing liquid 7 with the stirrer 8, the reactivity for forming gypsum increases.

By the air supplied into the circulation tank 4, reactions such as dissolution of limestone, dissolution of oxygen in the air, and crystallization of gypsum are simultaneously performed in the circulation tank 4. A part of the absorbent 7 extracted from the circulation tank 4 is conveyed to a gypsum recovery system from a line 37 branched from the circulation pipe 12 and collected as gypsum of dihydrate.

The processing gas from which most of the sulfurous acid gas has been absorbed and removed from the flue gas 3 by the absorbing solution 7 is supplied to the processing gas outlet 5.
The mist is removed by a mist remover (mist eliminator) (not shown in FIG. 1), and the mist is exchanged with high-temperature gas and released into the atmosphere from the chimney.

The embodiment of the absorption tower 1 shown in FIG. 14 has a structure in the absorption tower 1 when three flat plates 61 to 63 are installed. The absorption tower 1 shown in FIG.
This is a gas-liquid contact device in which a variable speed circulation pump 10 is mounted on the circulation pipe 2 in order to transport the water from the top to the top of the absorption tower 1.

On the other hand, FIG. 35 shows a conventional boiler exhaust gas 3.
Of the number of circulating pumps of the spray type desulfurization apparatus of the present invention. FIG. 35 shows that when the amount of combustion exhaust gas introduced into the absorption tower 1 and the concentration of sulfurous acid gas in the exhaust gas 3 fluctuate due to a change in boiler load, the absorption liquid 7 conveyed to the spray device 67 provided in the absorption tower 1 FIG. 4 is a control system diagram for controlling the number of circulation pumps 68 for controlling the supply amount from a limestone slurry supply pipe 36.

In the conventional method shown in FIG. 35, a plurality of spray devices 67 are provided in the height direction of the absorption tower 1, and a supply device for distributing the absorbing liquid 7 is attached to each spray header. Each spray header is provided with a circulating pump 68 for supplying the absorbing liquid. A circulating pump 68 which operates by detecting the boiler load and calculating the amount of absorbent in accordance with the load
Is used to control the number of devices.

During the daytime when the boiler load is large, the plurality of circulating pumps 68 are fully operated, and when the amount of power consumption at night is small, the number of operating circulating pumps 68 is reduced. In this case, the stopped circulation pump 68 requires maintenance such as cleaning the piping system in which the circulation pump 68 is located again at the time of startup under a high boiler load.

Normally, in the spray device 67, a swirling flow is mechanically applied at the tip of the spray nozzle by the back pressure to atomize the absorbing liquid 7. The back pressure required for atomizing the absorbent varies depending on the spray nozzle model, etc.
1.5 kg / cm ² is added. Therefore, in a conventional spray desulfurization apparatus, when the transport amount is controlled by a variable speed circulating pump, a required back pressure is selected when the transport amount is large.

However, when the load is low, the predetermined back pressure cannot be obtained, and the particle diameter of the droplet sprayed from the spray nozzle becomes large. As a result, the gas-liquid contact area cannot be secured, and the desulfurization performance is reduced. Cause you to Therefore, in the spray method, the number of circulation pumps is often controlled, and it may be difficult to employ a variable speed circulation pump due to the structure of the absorption tower 1.

In the absorption tower shown in FIG. 14, the amount of the absorbing liquid corresponding to the amount of change in the load can be arbitrarily adjusted by the variable speed circulation pump 10 and supplied to the flat plates 61 to 64. Here, the embodiment of FIG. 2 shows the result of the study of the atomization phenomenon of the droplet by the air current by the inventors.

FIG. 2 shows that a single droplet having a different particle size is ejected into an airflow flowing in a wind tunnel, and the state of division of the droplet is image-processed. , Countercurrent,
The results measured for the horizontal flow are shown below.

The critical relative velocity Rv at which the division of a droplet starts
Decreases as the droplet diameter dp increases. From this result, it was clarified that the larger the droplet diameter dp, the more easily the droplet is split.

FIG. 3 is a graph summarizing the drag received by the droplet from the gas fluid when the division of the droplet starts. As a similar parameter expressed as a ratio of the fluid force received from the gas to be treated 3 in the contraction part in the absorption tower 1 to the surface tension of the liquid, a dimensionless number such as the Weber number We can be considered.

Droplet-based relative velocity vt to gas flow
Is multiplied by the droplet diameter dp, and further multiplied by the gas density ρa is the fluid force received from the fluid. The Weber number We is expressed by a value obtained by dividing this fluid force by the surface tension σ of the liquid. It is. We = ρa × vt ² × dp / σ It is clear from the results shown in FIG. 3 that most of the droplets split at a Weber number We of 2 to 5. That is, it can be seen that the larger the droplet diameter dp, the smaller the drag received from the fluid force, but the more the liquid droplets dp.

FIG. 3 shows that the gas 3 and the droplets have the same web diameter when the flow direction of the gas flow is horizontal, even when the gas diameter and the droplet diameter are the same. This indicates that droplet division does not occur unless the number We is increased. It has been clarified that this difference is due to the division form of the two.

In any case, when the drag applied to the droplet from the fluid is 2 to 5 times the liquid surface tension σ, the droplet is divided, and the larger the droplet diameter dp, the more easily the droplet is divided. In the embodiment of FIG. 1, the relative speed of the gas 3 and the absorbing liquid 7 immediately before the absorbing liquid 7 falls from the lower ends of the flat plates 61 to 64 greatly contributes to the absorption liquid splitting.

From the drop splitting experiments shown in FIGS. 2 and 3, with respect to the embodiment of FIG. 1 from the viewpoint of atomization of the absorbing solution 7, at least the relative velocity between the gas 3 and the absorbing solution 7 is 5 m / s.
It is necessary to adjust so that it becomes above.

By increasing the relative velocity between the gas 3 and the absorbing liquid 7, atomization of the absorbing liquid 7 is promoted.
The upper limit of the relative velocity is determined by setting the cross-sectional area Am of the horizontal empty tower in the main flow section of the absorption tower 1 and the ventilation loss affected by the projected cross-sectional area As viewed from above and below the flow section of the gas 3 confined by the flat plates 61 to 64. Determined by value.

In order to explain the dimension relation of the flat plates 61 to 64 that restrict the gas flow affecting the ventilation loss, a horizontal sectional view of the absorption liquid passage portion of the absorption tower 1 (FIG. 4)
FIG. 4B is a sectional view taken along line AA of FIG. 4A and FIG. FIG. 4B shows a state in which four identical flat plates 61 to 64 are installed in the absorption tower 1.

Horizontal sectional area Am of the main stream of the absorption tower 1
The gas to be treated (exhaust gas 3) is introduced into (= Wx · Wy), and the gas flow is restricted by the flat plate 61. The horizontal sectional area Am of the main stream portion of the absorption tower 1 is constrained by the flat plate 61, and the projected sectional area As (in the vertical direction) in the gas flow direction (vertical direction) of the opening (contraction section) of the absorption tower 1 through which the gas 3 passes. = Ab), the gas 3 and the absorbing liquid 7 pass.

Here, Wx and Wy are the lengths of the respective sides of the cross section of the horizontal main tower section Am of the rectangular mainstream portion of the absorption tower 1, and a and b are the openings (shrinkage) of the absorption tower 1, respectively. It is the length of each side of the projected rectangular cross section in the vertical direction of the flow section). Further, the length of each of the flat plates 61 to 64 is P1, and the length from the end of the flat plate in the direction of extension of the flat plate to the wall surface of the absorption tower 1 is P1.
Let it be 2.

The ventilation loss of the gas flow flowing in the mainstream portion of the absorption tower 1 depends on the vertical cross-sectional area As of each of the contraction portions formed by the flat plates 61 to 64.

Further, the flat plates 61 to 64 are inclined downward by an angle θ with respect to the horizontal, and the plurality of flat plates 61 to 64 installed in the height direction are alternately changed in direction as shown in FIG. It is installed in a staggered arrangement. The interval between the flat plates facing each other is set by the angle θ and the installation height Hh of each of the flat plates 61 to 64. Further, the flat plate 61 shown in FIG.
Combinations # 64 are also effective when applied to the configurations shown in FIGS.

FIG. 5 shows a structure in which the vertical cross-sectional area As of the contraction section formed by each of the flat plates 61 to 64 is made at the center and both sides of the absorption tower 1. Horizontal cross-sectional view (FIG. 5 (a)) and FIG. 5 (a) of the absorption liquid passage portion of the absorption tower 1.
FIG. 5B is a sectional view taken along line AA of FIG.

That is, a pair of flat plates 61a and 61b (having the same shape) face each other from both wall surfaces having the same height of the absorption tower 1 and have a downward inclination angle such that an opening is formed at the center of the absorption tower 1. θ, and a pair of flat plates 62a, downstream of the pair of flat plates 61a, 61b.
62b (same shape) are arranged so that both ends are in contact with each other at the center of the absorption tower 1 and are convex upward, and openings are provided on both sides of the absorption tower 1.

A pair of flat plates 61 inclined downward so as to form an opening at the center of the absorption tower 1.
a, 61b and a pair of flat plates 62a, which are arranged so that both ends are in contact with each other at the center of the downstream side of the absorption tower 1 so as to be convex upward, and openings are provided on both sides of the absorption tower 1; 6
A plurality of combinations of 2b are provided in the gas flow direction in the absorption tower 1. Hereinafter, the flat plates 63a and 63b and the flat plate 64a,
64b are also flat plates 61a and 61b and flat plates 62a and 62b, respectively.
2b.

FIG. 6 (horizontal sectional view (FIG. 6 (a)) of the absorption liquid passage portion of the absorption tower 1 and a sectional view taken along line AA of FIG. 6 (a) are shown in FIG.
(B). ) Is an example in which the sizes of the plurality of flat plates 61 to 64 are respectively changed. FIGS. 7 and 8 show an example in which a plurality of triangular restraints 65 and semicircular restraints 66 are staggered in the mainstream portion of the absorption tower 1 instead of the flat plates 61 to 64 in the absorption tower 1. Is shown.

FIG. 7 (b) is a horizontal sectional view (FIG. 7 (a)) of the absorption liquid passage portion of the absorption tower 1 and a sectional view taken along line AA of FIG. 7 (b).
FIG. 8 is a horizontal sectional view of a portion of the absorption tower 1 through which the absorbent 7 passes.
FIG. 8B is a sectional view taken along line AA of FIG. 8A and FIG.

In any of the above absorption tower configurations, the absorption performance such as the ventilation loss of the gas flow and the desulfurization performance of the gas to be treated 3 is as follows:
It is influenced by the size or the adjustment area ratio (As / Am ratio) of the opening (contracting portion) which becomes the passage of the gas 3 to be treated and the absorbing liquid 7 which are confined by the flat plates 61 to 64 or the restricting objects 65 and 66. You.

FIG. 9 is a perspective view of the embodiment of the shape of the flat plates 61 to 64, and FIGS. 9A to 9D show typical examples of corrugated and curved plates. If the absorption tower 1 becomes large, the flow of the absorbing liquid 7 flowing down the flat plates 61 to 64 becomes uneven in the width direction. In addition, the number of installation stages of these internal components is appropriately selected according to the size of the absorption tower 1 and the like.

In the absorption tower configuration of the present invention, the adjusted area ratio (A
s / Am ratio), gas flow ventilation loss ΔP and flat plates 61 to 61
FIG. 10 shows the average droplet diameter dp of the absorbing liquid 7 flowing down through 64.
There is a relationship.

As shown in FIG. 10, the adjusted area ratio (As /
Am ratio), the ventilation loss ΔP of the gas flow decreases, and the average droplet diameter d of the absorbent 7 after flowing down the flat plates 61 to 64.
p also tends to be large. Conversely, the adjusted area ratio (As /
Am ratio), the ventilation loss ΔP increases,
The average droplet diameter dp also decreases.

Therefore, when designing the absorption tower 1, the amount of gas to be treated, the capacity of the blower, the ventilation loss, and the like are determined, so that the main tower of the absorption tower 1 is cut horizontally so that the ventilation loss ΔP is acceptable. Area Am or adjusted area ratio (As /
Am ratio).

The desulfurization performance is affected by the sulfur oxide concentration in the gas 3 to be treated, the amount of the gas to be treated, the amount of the absorbing solution to be contacted per unit gas amount, and the state of atomization of the absorbing solution 7 in the absorption tower 1. FIG. 11 shows a relationship between the average droplet diameter dp of the absorbent 7 and the absorption performance (desulfurization performance, etc.) of the absorbent 7.

Therefore, when the adjustment area ratio (As / Am ratio) is adjusted and the average droplet diameter dp of the absorbing liquid 7 is reduced, the gas-liquid contact area which affects the mass transfer amount can be increased, and the desulfurization rate increases.

However, since the ventilation loss ΔP has a relationship as shown in FIG. 10, the adjusted area ratio (As / Am ratio) or the horizontal flow of the main flow portion of the absorption tower 1 is set so that the allowable ventilation loss ΔP is set. It is important to determine the superficial section Am. When the amount of gas to be processed increases, it can be dealt with by unitizing the unit section as shown in FIG. 4 as in the apparatus shown in FIG. 1 and arranging a plurality of sets.

In the embodiment shown in FIG. 1, the gas flow direction and the flowing direction of the absorbing liquid 7 are the same co-current flow. However, from the viewpoint of increasing the relative velocity based on the droplet and promoting the atomization of the absorbing liquid 7, the gas 3 to be treated is transferred to the lower part (circulation) of the absorbing tower 1 as shown in the embodiment of FIGS. It is also possible to raise the gas flow from the tank 4 side) to make the gas flow countercurrent to the flowing direction of the absorbing liquid 7.

FIG. 12 is a structural view of the absorption tower 1 and the circulation tank 4. FIG. 13 is a horizontal sectional view (FIG. 13 (a)) of the absorption liquid passing portion of the absorption tower 1 and FIG. FIG. 13B is a sectional view taken along line AA. The reference numerals shown in FIGS. 12 and 13 are the same as those of the apparatus described with reference to FIGS. 1 and 4, respectively, and a description thereof will be omitted.

Hereinafter, embodiments of the gas-liquid contact device according to the present invention will be described with respect to the characteristics of gas flow ventilation loss and absorption performance (desulfurization performance) of the absorbent 7.

FIG. 15 shows a downward inclination angle 3 with respect to the horizontal.
The flat plates 61 to 64 of 0 ° are installed in four stages, and the cross section area Am of the hollow tower in the horizontal direction of the absorption tower 1 (Am = Wx × Wy), the flat plate 61
To 64 in the vertical cross-sectional area As (As = b
(Wx-a)), the absorption liquid flow rate (liter) per unit cubic meter of the processing gas amount is defined as the gas-liquid flow rate ratio L / G.
And the ventilation loss ΔP (mmAq) of the gas flow when the gas-liquid flow ratio L / G changes.

The parameters in FIG. 15 are the gas flow rates based on the superficial section area Am of the absorption tower 1 (hereinafter, superficial gas flow velocity Vo).
Is shown. The ventilation loss ΔP increases when the gas-liquid flow rate ratio L / G is increased if the same superficial gas flow velocity Vo is used, and when the superficial gas flow rate Vo is increased when the same gas-liquid flow rate ratio L / G is used,
There is a characteristic that the ventilation loss ΔP increases.

Naturally, the ventilation loss ΔP is equal to the gas-liquid flow ratio L /
G, the projected sectional area As of the contraction part even at the superficial gas flow velocity Vo
Has a significant effect. In the present desulfurization apparatus, there is a characteristic that the ventilation loss ΔP decreases as the projected sectional area As of the contraction portion increases.

Similarly, in the embodiment shown in FIG. 16, the gas-liquid flow ratio L / G in the absorption tower is kept constant at 15 (liter / m ³ N), and the horizontal cross section As The ratio (As / Am: opening ratio) of the direction to the hollow section area Am is 2
The relationship between the superficial gas flow velocity Vo (m / s) and the ventilation loss ΔP when changing to 5, 35, 50, 06, and 70% is shown.
In order to reduce the ventilation loss ΔP, it is necessary to increase the projected sectional area As of the contraction portion.

The embodiment shown in FIG. 17 shows the desulfurization performance of the flue gas when four flat plates 61 to 64 are installed on the wall surface of the absorption tower at an inclination angle of 30 ° with respect to the horizontal.

The experimental conditions in FIG. 17 were such that the sulfur dioxide concentration (SO ₂ concentration) in the gas at the inlet of the absorption tower 1 was 965 ppm on average.
The test was performed under the condition that the sulfite generated in the circulation tank 4 was totally oxidized. The adjustment was performed by supplying limestone so that the pH of the absorbing solution 7 became 5.4 to 5.6.

The desulfurization performance can be increased by increasing the gas-liquid flow rate ratio L / G if the same superficial gas flow velocity Vo, and if the same superficial gas flow rate L / G, the superficial gas flow rate Vo can be increased. Desulfurization performance can be improved. The present desulfurization apparatus has a superficial gas flow velocity Vo
When the value is increased, the desulfurization performance also increases, and the ventilation loss ΔP also increases.

Similarly, assuming that the gas-liquid flow ratio L / G = 15 liter / m ³ N is constant, the superficial gas flow velocity Vo and the desulfurization performance η
FIG. 18 shows the relationship of _SO2 . The parameter in FIG. 18 is a ratio of the horizontal cross-sectional area Am of the absorption tower 1 in the horizontal direction to the vertical cross-sectional area As of the contraction section (As / Am: opening ratio).
And the desulfurization performance when the opening ratio was changed from 25% to 70%.

In the measurement shown in FIG. 18, the inclination angles of the flat plates 61 to 64 were fixed at 15 ° downward with respect to the horizontal, and the number of flat plates 61 to 64 was four. If the superficial gas flow velocity Vo and the gas-liquid flow rate ratio L / G are constant, the desulfurization performance is almost constant without being affected by the cross-sectional area of the contraction part. There is a characteristic that increases. Thus, the gas-liquid contact device of the present invention has a close relationship between the ventilation loss ΔP and the desulfurization performance.

FIG. 19 shows the results obtained by organizing the ventilation loss ΔP of the absorption tower 1 and the mass transfer capacity Kog · a. The mass transfer capacity Kog · a has a characteristic that it increases as the ventilation loss ΔP increases. Desulfurization performance and mass transfer capacity Kog · a
It is well known that the following relationship exists, and that as Kog · a increases, the desulfurization performance can be increased. Desulfurization rate η _SO2 = (1-exp (Kog · a · Z · P /
Gm)) × 100 Here, Z is a gas-liquid contact effective height, P is a system pressure, and Gm is a gas flow rate.

FIG. 20 shows the relationship between the mass transfer capacity Kog · a and the desulfurization rate η _SO2 . The parameter in the figure is the superficial gas flow velocity Vo, which corresponds to the gas flow rate Gm since the superficial cross-sectional area Am (= Wx × Wy) is constant.

When the SO ₂ concentration in the exhaust gas 3 decreases, the ventilation loss Δp and the mass transfer capacity Kog · a have the relationship shown in FIG. When the concentration of SO ₂ in the gas to be treated 3 decreases, the mass transfer capacity Kog · a increases, and the desulfurization rate η _SO2 also increases.

In the gas-liquid contact device of the present invention, the absorption tower 1
The main parameters related to the gas flow ventilation loss ΔP, the desulfurization performance are: superficial gas flow velocity Vo, gas-liquid flow ratio L / G, superficial tower cross-sectional area Am, contraction part vertical projection area As, flat plates 61 to 61
64, the inclination angle θ, and the like.

The absorption tower 1 for the gas-liquid contact device of the present invention
In summary of the gas flow ventilation loss ΔP in the inside, FIG.
As shown in the figure, the ventilation loss ΔP is 2.3 of the superficial gas flow velocity Vo.
To the square of the gas-liquid flow ratio to the power of 0.87, and the ratio (As / A) of the vertical projection area As of the contraction part to the superficial section area Am
m) has a property proportional to the −2.13 power. Thus, the ventilation loss ΔP is greatly affected by the superficial gas flow velocities Vo and Am.

On the other hand, FIG. 23 shows an embodiment in which main parameters relating to the desulfurization performance are arranged. Mass transfer capacity K
og · a is -1.94 of the superficial gas flow velocity Vo, 0.61 of the gas-liquid flow ratio L / G, and 0.4 of the number of plates 61 to 64, and the inclination angle is −. It can be increased in proportion to the 0.46 power. It is clear from this that the desulfurization performance is affected by the superficial gas flow velocity Vo.

As shown in FIG. 18, the characteristics of the gas-liquid contact device of the present invention are that the desulfurization performance can be increased as the superficial gas flow velocity Vo increases, and
The ratio (As / Am) of the s to the superficial tower sectional area Am (As / Am) is 70%.
By increasing it to such an extent, the ventilation loss ΔP can be reduced.

FIG. 24 shows a gas-liquid contact device of the present invention (FIG. 24).
(A)) and a conventional spray type absorption tower (FIG. 24).
FIG. 3B shows a principle diagram. The spray-type apparatus is characterized in that the gas to be treated 3 is brought into gas-liquid contact with the droplets obtained by mechanically atomizing the absorbing liquid 7 at the tip of the spray nozzle, and a large gas-liquid contact area is secured. On the other hand, the gas-liquid contact device of the present invention, when flowing down the internal object, the gas 3 to be treated and the absorbent 7
Is characterized in that a two-phase flow mixed state is formed.

In the gas-liquid contacting apparatus of the present invention, when planning the absorption tower 1 with the superficial gas flow velocity Vo of 5 m / s, 15 liters of the absorption liquid 7 per cubic meter of gas to be treated is used.
And the gas-liquid contact, the desulfurization rate is 93 to 95 even when the sulfurous acid gas concentration in the gas to be treated 3 is around 1000 ppm.
% And a high value can be obtained.

This is because the liquid-side boundary film at the gas-liquid interface of the absorbing liquid 7 is well renewed, so that the liquid-side absorption resistance can be reduced. This is also estimated from the point that the mass transfer capacity Kog · a is two to three times higher than other gas-liquid contact devices, as shown in FIG.

The gas-liquid contact device of the present invention is characterized in that when the absorbing liquid 7 flows down the flat plates 61 to 64, the flat plates 61 to 64
Above is that a flow velocity distribution is generated based on the shearing force in the liquid thickness direction. FIG. 2 shows the flow velocity distribution in the liquid film thickness direction.
As shown in FIG. 5, the flight trajectory (flight distance) differs when the absorbent 7 scatters from the edge of the flat plate. That is, the flat plates 61 to 64
FIG. 26 shows the flow velocity distribution of the absorbing liquid 7 in the thickness direction of the liquid flowing down the liquid.
It becomes as shown in. The flow velocity becomes higher as the upper surface of the liquid film flows down the flat plates 61 to 64.

When such a flow velocity distribution occurs, the flat plate 6
The flight distance differs when leaving 1 to 64, and a thin liquid film is formed in the flight distance direction of the droplet as shown in FIG. This liquid film is treated gas stream, further diluted, it acts to expand the gas-liquid contact area, so that to enhance the absorption performance of the SO ₂ in the case of boiler exhaust gas 3. Flat plate 61
The thickness of the liquid film above No. 64 varies depending on the gas-liquid flow ratio, the length of the flat plate, its inclination angle, and the like.

In the case of planning the absorption tower 1 having the above-mentioned superficial gas flow velocity Vo of 5 m / s, the gas-liquid flow ratio L / G is set to 15 liters per cubic meter of the gas to be treated, and the absorption liquid 7 is set to 15 liters.
A case where the gas-liquid contact with the gas to be treated 3, per flat unit cubic meter, absorption solution 7 of about 9m ³ per minute flat 61
６４64. Flat plates 61 to 61 in this case
The thickness of the liquid flowing on 64 is 5 to 8 mm.

The absorbing liquid 7 that has flowed down on the flat plate 61 on the front stage flies to the flat plate 62 on the next stage. The flight distance of the absorbing liquid 7 varies depending on the inclination angle of the flat plate 61 and the like.
Fly about m. The absorbing liquid 7 that has fallen on the flat plate 62 in the next stage is scattered, entrains the gas 3 to be treated, and performs high-level gas-liquid contact in a gas-liquid two-phase flow state.

The present invention can be said to be a dynamic atomizer that forms a two-phase flow of the absorbing liquid 7 and the gas 3 flowing down the flat plates 61 to 64 without applying a mechanical swirling flow by a spray nozzle or the like. Therefore, since the mechanical power can be reduced as in a spray nozzle or the like, the power consumption in the absorbent circulation pump system can be reduced by 35 to 45%. It is also characterized in that there is no influence on the desulfurization performance due to the drift of the gas flow in the absorption tower 1 or the like.

Although the configuration of the flat plates 61 to 64 shown in the above embodiment is a simple flat plate, the absorbing liquid 7 of the flat plates 61 to 64 is used.
A drastic increase in desulfurization performance can be seen, for example, by setting up a weir at the falling part of the area. It is considered that this is because the absorbing liquid 7 flowing down at the weir at the end of the flat plate rebounds and increases the gas-liquid contact area.

FIG. 27 shows a state in which only the absorbing liquid 7 flows down to the flat plates 61 to 63 by its own weight (FIG. 27A) and a state in which a predetermined gas 3 flows (FIG. 27B) 2) shows a visualized photograph.

In the absorption tower 1 of the present invention, flat plates 61 to 64
When flowing down, turbulence and atomization of the absorption liquid 7 occur actively, and the mass transfer capacity Kog · a is increased. Furthermore, even when the absorbing liquid 7 flows down on the same flat plates 61 to 64, by changing the flat plate structure, the gas-liquid contact area a is increased, and the mass transfer capacity Kog · a can be increased.

The feature of the gas-liquid contacting device of the present invention is that the mass transfer capacity Kog · a can be increased, and at the same time, a mechanical shearing force is applied to the absorbing liquid 7 as in an absorbing liquid spray type device to atomize the liquid. It is not necessary to thoroughly perform the potential energy possessed by the absorbing liquid 7 conveyed to the upper part of the absorption tower 2 by the circulation pump, and to consume it for atomization of the absorbing liquid 7, thereby increasing the gas-liquid contact area a. However, the mass transfer capacity Kog · a can be increased.

FIG. 28 shows an experimental apparatus for examining the flight trajectory and dispersion and atomization of the flowing liquid having a flat plate structure. The experimental apparatus supplies the liquid to the toy-shaped flat plate 101 having a width of 100 mm.
The behavior of the flowing liquid, the flight distance, and the state of atomization were quantified by image processing with respect to the weir structure installed at the lower end portion of No. 01.

In the experiment, the amount of liquid supplied from the liquid tank 100 via the circulation pipe 103 via the circulation pipe 103 via the flow meter 105 while the inclination angle θ of the flat plate 101 with respect to the horizontal And flowed down from the flat plate 101.

FIG. 29 shows a photograph (FIG. 29 (a)) of the flight trajectory when the absorbing liquid 7 flows down from the inclination angle θ = 30 ° with respect to the horizontal of the flat plate 101, and FIG.
X, Y starting from the flat plate edge when changing to 0, 45 °
30 is a graph showing the measurement results of the flight distance of the absorbing liquid 7 in coordinates (FIG. 29B).

As shown in the photograph of the flight trajectory of the absorbing liquid 7 in FIG. 29 (a), the flat plate 1 has an inclination angle θ = 30 ° with respect to the horizontal.
The absorbent 7 flowing down from 01 becomes a flight trajectory in a liquid column state. If the flight distance of the liquid flowing down from the flat plate 101 is represented on the X and Y coordinates, a flight trajectory shown in FIG. 29B is drawn, and the flatter the tilt angle θ of the flat plate 101 is, the longer the flight is.

FIG. 30 shows the flight trajectory of droplets and the state of atomization when a weir is provided at the end of the flat plate 101 shown in FIG. The photograph of the flight trajectory of the droplet (FIG. 30A) and the flat plate 1
31 is a graph showing the measurement results of the flight distance in X, Y coordinates with the plate end as the base point when the inclination angle θ of 01 is changed to 15, 30, 45 ° (FIG. 30 (b)).

As can be seen by comparing FIG. 29 and FIG. 30, even if the inclination angle θ of the flat plate 101 with respect to the horizontal is the same as 30 °, the flight locus of the flowing liquid becomes longer by providing the weir. In the example of FIG. 30 having no weir, the state of a liquid column can be observed, while the state of a considerably atomized droplet can be observed. Therefore, when the absorbing liquid 7 is caused to flow down from the flat plate 101, it is more effective to atomize the liquid than to simply flow down the flat plate 101 on the end of the flat plate 101.

Further, comparing the relationship between the downward inclination angle θ of the flat plate 101 with respect to the horizontal and the flight distance, the greater the angle of inclination from horizontal to downward by providing the weir, the longer the flight distance of the flowing liquid. Compared to the case where no weir is installed, the relationship between the inclination angle θ and the flight distance is reversed, and the greater the inclination angle θ, the longer the flight distance.

Accordingly, from the viewpoint of desulfurization performance, it can be said that the more effective the absorption tower is, the more the gas flowing down becomes longer as the falling liquid is atomized and the farther it is, the farther it is made.

Further, when there is a weir at the end of the flat plate, the flowing liquid collides with the weir, and the atomization is highly promoted, which is effective in further promoting the atomization.

In the example shown in FIG. 30, as the inclination angle θ of the flat plate 101 downward from the horizontal is larger, the falling liquid film becomes thinner, the average velocity of the flowing liquid becomes faster, and the flight distance becomes longer. When a weir is installed at the end of the flat plate, the flowing liquid collides with the weir and is an effective means from the viewpoint of atomization.

Therefore, in order to increase the atomization of the flowing liquid in the gas-liquid contacting device of the present invention, the potential energy of the flowing liquid lifted to the upper part of the absorption tower 1 by the pump is thoroughly used for atomizing. It is effective to install a weir in the lower groove of the flat plates 61 to 64, but it was further clarified that the presence of the weir greatly affected the structure of the weir.

When there is a weir at the end of the flat plate, the flight distance of the flowing liquid affects the height of the weir. The flight distance of the liquid flowing down from the flat plates 61 to 64 is represented by the following formula, with the average liquid film thickness δ of the flowing liquid flowing down the flat plates 61 to 64 under the turbulent flow condition where the flowing liquid amount is large. It is. δ = K · Re ^M · (μ ² / g · sin θ · ρ ² ) ^1/3 (2) where Re is Reynolds number, μ is viscosity, ρ is density, θ
Is the inclination angle of the flat plates 61 to 64 with respect to the horizontal. M is a constant of approximately 0.583, and K is a constant of approximately 0.34, which differs depending on the flat plate configuration.

Therefore, as the thickness δ of the falling liquid film is reduced, the average flow velocity when flowing down the flat plates 61 to 64 is increased, and the flying speed of the flowing liquid is increased by increasing the amount of flowing liquid per unit area of the flat plate. .

The thickness δ of the falling liquid film can be adjusted by adjusting the width Wy of the absorption tower 1 shown in FIG. Therefore,
When the amount of flowing liquid per unit area of the flat plates 61 to 64 is fixed, it is effective to adjust the liquid film thickness δ in the range of 0.5d to 20d by adjusting the width Wy of the absorption tower 1 from the flying distance. Become.

Here, the average flow velocity V _av flowing down the flat plates 61 to 64 can be determined from the liquid film thickness δ and the flowing liquid amount. Therefore, the flight trajectory (flight distance) of the flowing liquid starting from the ends of the flat plates 61 to 64 can be obtained by obtaining the velocity vector of the equation of motion, and the flight distance corresponding to the experiment.

The flight distance from the flat plates 61 to 64 is determined when planning the desulfurization apparatus on which the absorption tower 1 is mounted, when determining the point for increasing the gas-liquid contact time and determining the area of the contraction part (opening). One of the important parameters.

FIG. 31 is an atomized photograph of a V-shaped groove weir in which the flowing liquid is atomized using the experimental apparatus shown in FIG. 28 (FIG. 31).
(A)) and the flight trajectory (FIG. 31 (b)).
Shows a perspective view (FIG. 32 (a)) of a typical example of the weir configuration and a groove shape (FIG. 32 (b)) viewed from the front.

As shown in the photograph of FIG. 31 (a), the liquid flowing down from the flat plate 101 is highly atomized, and the contact area a between the absorbing liquid 7 and the gas 3 to be treated as the absorption tower 1 is increased. It is effective from the viewpoint of doing.

The structure of the weir 200 is a typical example of a U-shaped groove 200-b and a W-shaped groove 2 other than the V-shaped groove 200-a.
As shown in the example of 00-c, when flying from the flat plate 101, it is possible to generate a velocity distribution in the cross-sectional area direction which depends on the liquid film thickness of the formula (2) at the end of the flat plate. It turned out to be effective for

The flat plate 101 has a V-shaped groove 20
Instead of weirs represented by 0-a, U-shaped groove type 200-b, W-shaped groove type 200-c, and a combination thereof, a V-shaped groove-shaped flat plate 100-a as shown in FIG. Flat plate 1
In the case of the 00-b, W-shaped groove-shaped flat plate 100-c, the effect of atomizing the flowing liquid can be expected to be the same as the effect of installing the weir 200 on the inclined flat plate 101.

V-groove flat plate 100-a, U-groove flat plate 1
The flat plate 100-b and the W-shaped grooved flat plate 100-c are effective in terms of strength as the flat plate 101 that actually receives and flows down the absorbing liquid 7 corresponding to about 9 tons / minute per unit square meter.

In the gas-liquid contact device of the present invention, the falling liquid is finely divided by forming a weir or a V-shaped groove-shaped plate, a U-shaped groove-shaped flat plate, and a W-shaped groove-shaped flat plate 101 at the end of the flat plate 101 shown in FIG. Can be Further, the absorbing liquid 7 flowing down from the flat plate 101 receives a drag force from the gas 3 and is atomized.

Regarding the atomization phenomenon of the droplets, the droplets are ejected into the wind tunnel, and are arranged in the relationship between the droplet diameter and the Weber number We obtained from the relative speed at which the droplets start to be divided. Shown in

[0142] Weber number We, the gas density [rho _g relative speed Vr, the droplet diameter Dp, when a surface tension δ of the droplet ([rho _g ·
Vr ² · Dp / δ). Weber number W
e is the ratio between the drag acting on the droplet and the surface tension, and varies depending on the velocity vector received by the droplet even with the same drag. Dropping of droplets is more likely to occur as the droplet size increases.

When the droplet diameter is 3 mm or more, the We number at which division starts is 5 or less. Therefore, the equivalent particle diameter of the liquid flowing down the flat plate 101 is as large as about 10 mm when the gas 3 of the V-shaped groove weir 200-a is not flowing.

The relative velocity when the liquid 3 flowing down the flat plate 101 and the gas 3 flow in a gas-liquid multiphase flow state varies depending on the conditions, but is 7 to 13 m / s. 5 or more. Therefore, the liquid flowing down the flat plate 101 has an effect of increasing the gas-liquid contact area a by breaking up the droplets in the process of falling and becoming finer.

A summary of the experimental results is shown in FIG. 34, which is a typical example in which a desulfurization apparatus equipped with the gas-liquid contact device of the present invention is designed. The trial design conditions are as follows: the exhaust gas amount is 1,000,000 / h, the SO ₂ concentration in the exhaust gas 3 is 700 ppm, and the gas-liquid flow rate ratio L / G is brought into contact with 15 liters of the absorbing liquid 7 per m ³ N.

An absorption tower having a flat plate inclination angle of 30 °, a contraction part (opening) area through which gas 3 flows, of 6 m × 11 m, and two gas-liquid contactor units of the present invention installed in the absorption tower was planned. . One series of dimensions is 50% aperture ratio,
The four inclined steps, the step interval was 2 m, and the area of the contraction portion (opening) was 1.5 m in the opening length in the direction in which the falling liquid flies. Under such conditions, a desulfurization rate of 95% or more can be achieved.

[0147]

According to the present invention, the gas flow is restricted in the absorption tower of the gas-liquid contacting device, and an internal component such as a flat plate for generating a contraction is installed to form a contraction portion of the gas flow. Thus, gas-liquid contact becomes active at the contraction part.

Therefore, the absorption liquid 7 can be atomized under the condition of a high gas flow rate when the gas 3 to be treated is contracted in the contraction part. No power is required. ADVANTAGE OF THE INVENTION According to this invention, the absorption tower of a gas-liquid contact apparatus can be made compact and the running cost reduction in operation can be achieved.

When the gas to be treated 3 contracts in the contraction section, a high degree of gas-liquid contact between the liquid to be treated and the gas 3 to be treated occurs. In particular,
In the desulfurization method of the wet limestone / gypsum method, the renewal of the liquid-side interface of the liquid to be treated is effective to enhance the absorption performance. Therefore,
This is advantageous for conditions where the sulfur dioxide gas concentration in the combustion exhaust gas 3 is high.

Further, in order to form a two-phase flow between the liquid to be processed and the gas to be processed 3 flowing down on an internal object such as a flat plate and to make gas-liquid contact, electric power for mechanical atomization as in a spray method is employed. No volume is required, and the power consumption of the pump in the circulation line of the liquid to be treated can be reduced by 35% to 45%.

In a general gas-liquid contact device, it is necessary to pay attention to a uniform gas flow when introducing the gas 3 to be treated. However, the gas-liquid contact device of the present invention does not have a problem such as gas drift. The liquid to be treated supplied to the absorption tower of the present invention is controlled by a variable-speed circulating pump, whereby it is possible to quickly respond to a change in the flow rate of the gas to be treated 3 and to set the power consumption to an appropriate value. be able to.

Further, in the case of the spray nozzle, since the liquid to be treated is atomized by applying a constant back pressure, the liquid to be treated per unit spray header cannot be varied greatly. Difficult to use molds.
Therefore, it is necessary to provide a plurality of circulation pumps and control the number of operating pumps in order to cope with daily boiler load changes.

On the other hand, in the gas-liquid contact device of the present invention,
To apply a variable-speed circulating pump that can control the amount of conveyance by the number of rotations against changes in daily boiler load, etc. just to transport the liquid to be processed to the upper part of the absorption tower and distribute it to the flat plate Is possible.

Further, by providing a weir at the end of the flat plate, the atomization of the liquid flowing down from the flat plate can be enhanced, so that a higher desulfurization performance can be obtained, and the pump power for circulating the liquid to be treated can be increased. A gas-liquid contact device that can be reduced can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a gas-liquid contact device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a droplet diameter and a limiting relative velocity when a droplet in a gas flow in an absorption tower according to an embodiment of the present invention is split. "

FIG. 3 is a diagram showing the number of webers at which a droplet in an airflow in an absorption tower according to an embodiment of the present invention breaks.

FIG. 4 is a configuration diagram of a contraction section of a basic absorption tower according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of an application example of the contraction section of the absorption tower according to the embodiment of the present invention.

FIG. 6 is a configuration diagram of an application example of the contraction section of the absorption tower according to the embodiment of the present invention.

FIG. 7 is a configuration diagram of an application example of the contraction section of the absorption tower according to the embodiment of the present invention.

FIG. 8 is a configuration diagram of an application example of the contraction section of the absorption tower according to the embodiment of the present invention.

FIG. 9 is a view showing a shape of a flat plate used for a contraction portion of the absorption tower according to the embodiment of the present invention.

FIG. 10 shows A of the contraction section of the absorption tower according to the embodiment of the present invention.
It is a figure which shows the relationship between ventilation loss (DELTA) P with respect to s / Am ratio, and average droplet diameter dp.

FIG. 11 is a diagram showing the relationship between the average droplet diameter and the desulfurization rate in the absorption tower according to the embodiment of the present invention.

FIG. 12 is a configuration diagram of a gas-liquid contact device according to an embodiment of the present invention.

FIG. 13 is a configuration diagram of an application example of the contraction section of the absorption tower according to the embodiment of the present invention.

FIG. 14 is a configuration diagram of a gas-liquid contact device according to an embodiment of the present invention.

FIG. 15 is a diagram showing a relationship between a gas-liquid flow ratio, a superficial gas flow velocity, and a ventilation loss of the absorption tower according to the embodiment of the present invention.

FIG. 16 is a diagram showing a relationship between a superficial gas flow velocity, an opening ratio, and a ventilation loss of the absorption tower according to the embodiment of the present invention.

FIG. 17 is a diagram showing a relationship between a gas-liquid flow ratio, a superficial gas flow velocity, and a desulfurization rate of the absorption tower according to the embodiment of the present invention.

FIG. 18 is a diagram showing a relationship between a superficial gas flow velocity, an opening ratio, and a desulfurization rate of the absorption tower according to the embodiment of the present invention.

FIG. 19 shows ventilation loss of the absorption tower according to the embodiment of the present invention;
It is a figure which shows the relationship between a superficial gas flow velocity and mass transfer capacity Kog * a.

FIG. 20 is a diagram showing the relationship between the mass transfer capacity Kog · a and the desulfurization performance of the absorption tower according to the embodiment of the present invention.

FIG. 21 is a view showing the influence of the concentration of sulfurous acid gas on the mass transfer capacity Kog · a of the absorption tower according to the embodiment of the present invention.

FIG. 22 is a diagram showing various parameters affecting ventilation loss of the absorption tower according to the embodiment of the present invention.

FIG. 23 is a diagram showing the influence of various parameters on the mass transfer capacity Kog · a of the absorption tower according to the embodiment of the present invention.

FIG. 24 is a diagram illustrating characteristics of an absorption tower according to an embodiment of the present invention in comparison with a spray type absorption liquid spraying device.

FIG. 25 is a diagram illustrating a state of scattering of a flowing liquid from a flat plate used in the absorption tower according to the embodiment of the present invention.

FIG. 26 is a diagram showing a velocity distribution of a flowing liquid on a flat plate according to the embodiment of FIG. 25;

FIG. 27 is a visualized photograph showing the state of dispersion of the liquid to be treated flowing down on a flat plate in the absorption tower according to the embodiment of the present invention.

FIG. 28 is a configuration diagram of a flight trajectory experiment apparatus for a liquid flowing down a flat plate in an absorption tower according to an embodiment of the present invention.

FIG. 29 is a photograph and a diagram showing an experimental result of a flight trajectory of a liquid flowing down a flat plate in an absorption tower according to an embodiment of the present invention.

FIG. 30 is a photograph and a diagram showing an experimental result of a flight trajectory of a liquid flowing down a flat plate in an absorption tower according to an embodiment of the present invention.

FIG. 31 is a photograph and a diagram showing an experimental result of a flight trajectory of a liquid flowing down a flat plate in an absorption tower according to an embodiment of the present invention.

FIG. 32 is a configuration diagram of a flat plate with a weir in the absorption tower according to the embodiment of the present invention.

FIG. 33 is a diagram showing a shape of a flat plate in the absorption tower according to the embodiment of the present invention.

FIG. 34 is a diagram illustrating a relationship between a droplet particle size and a droplet atomization start We number in an absorption tower according to an embodiment of the present invention.

FIG. 35 is a diagram showing a system for controlling the number of circulation pumps of a desulfurization apparatus according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Absorption tower 2 Absorbing liquid supply pipe 3 Gas to be processed 4 Circulation tank 5 Processing gas outlet 7 Liquid to be processed (absorbing liquid) 8 Stirrer 9 Oxidation air 10 Variable speed circulation pump 12 Circulation pipe 17 Lime slurry 37 Gypsum collection line 61 , 62, 63, 64 flat plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 10/02 (72) Inventor Shuntaro Koyama 7-1-1, Omika-cho, Hitachi City, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Inside the Power and Electricity Development Laboratory, Ltd. (72) Inventor Ken Amano 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside the Power and Electricity Development Laboratory, Hitachi, Ltd. (72) Inventor Shigeru Nozawa 6, Takaramachi, Kure-shi, Hiroshima Prefecture No. 9 Babcock Hitachi Co., Ltd. Kure Works (72) Inventor Kenji Muramoto 6-9 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Co., Ltd. Kure Works F-term (reference) 4D002 AA02 AC01 BA02 BA13 BA14 BA16 CA02 CA04 DA05 DA16 EA02 EA12 FA03 GA02 GA03 GB02 GB03 GB06 HA08 4D020 AA06 BA02 BA09 BB05 CB20 CB21 CB34 CC03 CC08 CC21 CD01 CD02 DA01 DA02 DB01 DB04 DB05 DB20 4G075 AA03 AA45 BB04 BD03 BD07 BD13 BD22 BD23 BD26 EA01 EA05 EB02 EB04 EE12 EE21

Claims (17)

[Claims] 1. A gas-liquid contact method in which a gas to be treated and a liquid to be treated which absorbs a target component in the gas to be treated are introduced into an absorption tower and brought into contact with each other to absorb the target component in the gas to be treated. The liquid to be treated is caused to flow down into the absorption tower, and at least one gas-condensed portion of the gas to be treated is formed, and the gas to be treated is supplied to the gas-condensed portion so that the multi-phase flow of the liquid to be treated and the gas to be treated Wherein the liquid to be treated is divided by the fluid force generated when the gas to be treated is contracted, and the atomization is promoted. 2. The gas to be treated flows between the inlet of the absorption tower and the outlet of the absorption tower of the gas to be treated, wherein the relative velocity of the gas to be treated flowing through the contraction part with respect to the liquid to be treated is 5 m / s or more. Of the absorption tower in the horizontal direction (Am) and / or the cross section of the absorption tower in the horizontal direction (Am) and the opening of the contraction portion so that the ventilation loss of the absorption tower is equal to or less than the set value. 2. The gas-liquid contact method according to claim 1, wherein a ratio (As / Am ratio) of a projected sectional area (As) as viewed from above and below the portion is set. 3. The gas-liquid contact method according to claim 1, wherein the supply amount of the liquid to be treated to the absorption tower is controlled by using a circulation pump that adjusts the amount of the liquid to be treated according to the number of revolutions. 4. The web number We of the droplet is 2 <We = ρa × vt ² × Dp / σ <5, where vt: relative velocity of the droplet with respect to the gas flow, Dp: droplet diameter, ρa: gas density The gas-liquid contact method according to claim 1, wherein σ is the surface tension of the liquid. 5. The gas-liquid contact method according to claim 1, wherein the amount of the liquid to be processed flowing through the contraction section is not less than 50 liters per second and not more than 200 liters per square meter. 6. A gas-liquid contacting device having an absorption tower for introducing a gas to be treated and a liquid to be treated which absorbs a target component in the gas to be treated and bringing them into contact with each other to absorb the target component in the gas to be treated. 3. The gas-liquid contact device according to claim 1, wherein a plurality of internal components are installed in the absorption tower, and at least one contraction part for the flow of the gas to be treated and the liquid to be treated is provided. 7. A cross sectional area (As) as viewed from above and below of a contraction portion formed by an internal substance in a flow of a gas to be treated in an absorption tower, and a cross section area (Am) of an empty tower in a horizontal direction of the absorption tower. 7.) The gas-liquid contact device according to claim 6, wherein the ratio (As / Am) is 0.2 or more and 0.8 or less. 8. The internal component is a flat plate which is inclined downward with respect to the horizontal in the direction of the center of the absorption tower from the tower wall of the absorption tower, and the plurality of the flat plates alternately change the direction in the height direction. 7. The gas-liquid contact device according to claim 6, wherein the gas-liquid contact device is arranged in a staggered arrangement. 9. The internal components are arranged so as to be inclined one by one in the height direction of the absorption tower from the wall surface side opposite to the absorption tower toward the center portion, and the contraction portion formed by the internal components on the upper stage side 7. The gas-liquid contact device according to claim 6, wherein an arrangement relation is such that the liquid to be treated, which has flowed down, flows down onto the lower internal component. 10. The internal component is a flat plate which is inclined downward with respect to the horizontal in the direction of the center of the absorption tower from the tower wall of the absorption tower, and a weir is provided at the lower end of the flat plate. The gas-liquid contact device according to claim 6. 11. The height of the weir at the lower end of the flat plate is 0.5 d to 20 with respect to the thickness d of the liquid to be treated flowing down on the flat plate.
The gas-liquid contact device according to claim 10, wherein d is d. 12. The gas-liquid contact according to claim 10, wherein the weir at the lower end of the flat plate has a weir structure comprising a V-shaped groove weir, a U-shaped groove weir, a W-shaped groove weir, or a combination thereof. apparatus. 13. The gas-liquid contact device according to claim 6, further comprising a circulation pump for adjusting a supply amount of the liquid to be treated to the absorption tower by a rotation speed. 14. The method according to claim 1, wherein the sulfur oxide in the absorbent is oxidized by using an absorbent containing a desulfurizing agent that is brought into contact with the combustion exhaust gas to absorb the sulfur oxide in the exhaust gas. A wet flue gas desulfurization method. 15. A sulfur dioxide gas concentration, a moisture concentration, an exhaust gas temperature in the flue gas introduced into the absorption tower, and a sulfur dioxide gas concentration in the treated flue gas at the outlet of the absorption tower, respectively, are detected. The wet flue gas desulfurization method according to claim 14, wherein a required amount of absorbing liquid is calculated from the set desulfurization rate, and the amount of absorbing liquid transported to the absorption tower is controlled. 16. The wet exhaust system according to claim 6, wherein the absorption tower is an absorption tower that is brought into contact with combustion exhaust gas by using an absorbent containing a desulfurizing agent to absorb sulfur oxides in the exhaust gas. Smoke desulfurization equipment. 17. A means for detecting the amount of flue gas introduced into the absorption tower, the concentration of sulfur dioxide, the concentration of moisture, the temperature of the exhaust gas, the concentration of sulfur dioxide in the treated flue gas at the outlet of the absorption tower, and each of the detection means A calculator for calculating the required amount of liquid to be treated by inputting the signal detected in the above and the set desulfurization rate, and an absorption liquid transfer amount control for controlling the amount of absorption liquid to be transferred to the absorption tower by an output signal from the calculator. 17. The wet flue gas desulfurization apparatus according to claim 16, further comprising means.