JP5046755B2 - Gas-liquid contact device - Google Patents

Description

  The present invention relates to a gas-liquid contact device and a flue gas desulfurization device using the same.

A wet desulfurization apparatus is generally used as a desulfurization apparatus for coal-fired power plant exhaust gas and the like. In wet desulfurization equipment, sulfur oxides such as SO ₂ contained in exhaust gas are absorbed in contact with a solution containing alkali such as limestone, and the resulting solution containing sulfite ions is received in the reservoir, and then an oxygen-containing gas A process of converting to sulfate (gypsum) by catalytic oxidation with (generally air) is performed.

  In such a wet flue gas desulfurization apparatus, an alkali-containing solution is pumped up from a suction port provided in a liquid reservoir and used again as a sulfur oxide absorbing liquid. Since the desulfurization performance decreases when the liquid is used, it is necessary to sufficiently oxidize the sulfite ion by spreading the oxygen-containing gas over the entire liquid reservoir before sucking from the pump suction.

  As such a gas-liquid mixing and stirring means, a configuration in which a pipe that directly supplies gas to an aeration tank using a blower and a stirrer that shears and refines the supplied gas and pushes it forward is known. Recently, see FIG. 13 (c) of Patent Document 1 and Patent Document 2), but it is possible to realize a blower-less gas-liquid mixture supply, no moving parts, excellent maintainability, and low cost. Therefore, a jet air sparger [JAS] is preferably used.

  As shown in FIG. 9, JAS is a liquid supply pipe 92 having a flow passage narrow portion 91 formed therein, and a gas supply pipe 94 connected by providing an opening 93 in a downstream area of the flow passage narrow portion inside the liquid supply pipe. And a gas-liquid mixing and stirring means. The flow of the liquid supplied to the liquid supply pipe generates a negative pressure region 95 in the downstream area of the narrow portion of the flow path, and exhausts the gas 96 supplied from the branch pipe by the ejector effect while discharging it from the nozzle. Thereby, the supply of the jet including bubbles can be realized without using a blower.

However, the streamline of the gas-liquid mixed jet supplied from the JAS is linear, and the supply of the gas-liquid mixed stream in the direction perpendicular to the streamline tends to be insufficient.
Therefore, in the flue gas desulfurization apparatus so far, in order to ensure a sufficient bubble supply effect to the entire aeration tank 100 as shown in FIG. 10, a plurality of JAS 101 are provided on the side wall opposite to the side wall provided with the suction port 102. A configuration is adopted in which L2 is narrowed and arranged in parallel.
International Publication 00/009243 Pamphlet JP 2004-181327 A

Since JAS itself is inexpensive, it is possible to provide a plurality of JAS. However, in order to issue a jet flow at a predetermined pressure from each JAS, it is necessary to increase the output of the circulation pump, which inevitably increases the power consumption of the circulation pump.
There is also a problem that an excessive number of JASs must be arranged in the treatment of exhaust gas that has a low SO _x content and can supply a sufficient amount of oxygen for oxidation to the liquid reservoir even if the number of JASs is reduced.

  In view of the above-described situation, the present invention provides a gas-liquid contact device capable of performing efficient gas-liquid mixing and stirring when aeration is performed in a large absorption liquid reservoir, and a flue gas desulfurization device incorporating the gas-liquid contact device. The purpose is to provide.

The present invention has been made to solve the above problems. That is, in order to achieve the above object, the gas-liquid contact device according to the present invention comprises an aeration tank, a gas-liquid contact means provided with a gas-liquid mixing means having a nozzle tip penetrating the side wall of the aeration tank, and a stirrer. An apparatus, wherein the gas-liquid mixing means includes a liquid supply pipe in which a flow passage narrow portion is formed and an opening for pipe connection is provided downstream of the flow passage narrow portion, and an opening of the liquid supply pipe A gas supply pipe inserted into the liquid supply pipe, and by flowing the liquid into the liquid supply pipe, a negative pressure is generated in the vicinity of the opening downstream of the channel narrowing portion, and the gas is sucked from the opening and dispersed in the liquid. The stirrer is arranged at a position higher than the gas-liquid mixing means so that the stirring surface is perpendicular to the streamline of the jet flow supplied from the gas-liquid mixing means. It is what.
An exhaust gas desulfurization apparatus according to the present invention is an exhaust gas desulfurization apparatus for cleaning and desulfurizing sulfur oxides in combustion exhaust gas with an absorbing solution containing an alkali, the gas-liquid contact device and the gas-liquid contact A circulation pump for sucking the absorbing liquid from the suction port of the absorbing liquid provided in the aeration tank of the apparatus and circulating it to the liquid supply pipe of the gas-liquid contact device;
Sprinkling means for ejecting the absorbing liquid and bringing it into contact with the flue gas is provided.

By using the gas-liquid contact device of the present invention, the gas-liquid mixed flow can be distributed to the region where the circulating flow generated by the gas-liquid mixing means does not reach, and the effective volume of the aeration tank can be increased.
By using the gas-liquid contact device of the present invention, it is not necessary to consider the interval between adjacent gas-liquid mixing means, and the arrangement of the gas-liquid mixing means can be freely set. Further, even if the number of the gas-liquid mixing means is reduced, the bubbles can be spread throughout the aeration tank, so that it is possible to reduce the power consumption required for supplying the liquid to the gas-liquid mixing means.
In the flue gas desulfurization apparatus of the present invention, by adopting the gas-liquid contact apparatus of the present invention, as a result of being able to sufficiently oxidize sulfite ions generated by absorbing sulfur oxide over the entire aeration tank, It is possible to reduce sulfite ions in the absorbing solution sprayed by the spraying means, and to suppress a decrease in desulfurization performance.
The flue gas desulfurization apparatus of the present invention has a low sulfur oxide content, and JAS can be used to treat combustion exhaust gas that can supply a sufficient amount of oxygen for oxidation to the liquid reservoir even if the number of JAS is small. Therefore, the power consumption cost of the circulation pump for circulating and supplying the absorbing liquid to the JAS at a predetermined pressure can be reduced.

Hereinafter, the present invention will be described in detail with reference to the drawings. The same members are denoted by the same reference numerals. In addition, this invention is not restrict | limited to the form demonstrated below.
In the gas-liquid contact device of the present invention, gas-liquid mixing means is disposed from the side wall of the aeration tank toward the bottom surface. As the gas-liquid mixing means, a liquid supply pipe in which a channel narrow portion is formed inside and an opening for pipe connection is provided immediately after the channel narrow portion, and a gas supply pipe inserted into the opening of the liquid supply pipe Jet air in which a negative pressure is generated in a region immediately after the narrow portion of the flow path, and a gas is drawn from the opening and a jet flows out to the aeration tank together with the liquid. A sparger [JAS] can be employed.

The JAS in the aeration tank is arranged such that the tip of the nozzle faces the bottom of the aeration tank so that the bubbles are in sufficient contact with the liquid in the deep portion of the aeration tank.
As shown in FIG. 1, the streamline of the jet 12 blown out from the JAS nozzle 11 installed on the side surface of the aeration tank 10 is almost the same as the direction of the JAS nozzle 11 in the vicinity of the JAS nozzle 11, but the jet is After reaching the predetermined jet arrival distance L1, the momentum in the horizontal direction is lost, and the air travels upward in the vertical direction according to the buoyancy of the bubbles. As shown in the side view of the aeration tank in FIG. 2 (b), the jet reaching the water surface generates flows 21a and 21b along the jet direction of the jet. The flow 21a forms a circulation flow in the depth direction, and part of the flow 21b reaches the vicinity of the side wall 22 of the aeration tank 10, and as shown in the aeration tank plan view of FIG. A spread flow 21c is generated.
However, in the configuration using only the JAS nozzle 11, the lateral spread of the jet flow is poor, and a region 23 where bubbles do not reach sufficiently is generated. In addition, a region 24 where bubbles do not reach sufficiently is also formed in the region directly above or below the nozzle outlet.

As a result of diligent research, the present inventors have found that it is most efficient to install the stirrer so that the stirring surface is perpendicular to the streamline of the main jet of JAS in order to keep bubbles in the entire aeration tank. I found out.
“Stream line” means that the jet flow normally jetted from JAS turns into an upward flow with bubbles and reaches the water surface, so the point where the jet flow pressure or flow velocity of the fluid jetted from the JAS nozzle tip is the highest is the JAS nozzle. It is a line connected from the tip to the water surface. There are various methods for measuring the flow velocity of the fluid, such as measurement by dynamic pressure or ultrasonic interference. A three-dimensional electromagnetic flow sensor or the like is preferably used for measuring the flow in a large tank. The “stirring surface” refers to a surface through which a stirring blade passes among the surfaces perpendicular to the rotation axis of the stirrer.

As one embodiment of the present invention, in FIG. 3, the stirrer 31 is installed near the outlet of the JAS nozzle 32. In this embodiment, as is clear from FIG. 3B, the direction in which the JAS nozzle 32 faces and the stirring surface 36 of the stirrer 31 are installed directly above the JAS nozzle 32. By installing the stirrer in this way, the radial flow 34 and the rotation shaft are newly provided from the rotation center of the stirrer so as not to disturb the JAS main jet 33 but rather to complement the area where the JAS main jet does not reach. A directional flow 35 is created, creating a new circulating flow to supply sufficient bubbles to the region 22 with few bubbles directly above or below the nozzle outlet.
The stirrer 31 is usually provided at a position higher than the JAS nozzle 32. This is because if the water is provided at a position lower than the JAS nozzle 32, the water pressure increases as the water depth increases, and the power required to drive the stirrer 31 inevitably increases.
The rotation speed of the stirrer is usually between 10 rpm and 100 rpm. If it is less than 10 rpm, the gas supply to the region with few bubbles may be insufficient, and if it exceeds 100 rpm, the JAS main jet may be disturbed.
As long as the agitator is installed at a position higher than the JAS nozzle, it is not limited to the position directly above the JAS nozzle in the vertical direction. For example, the agitator is installed at a position between the JAS nozzles arranged in parallel on the side wall of the aeration tank. Also good.
Moreover, the number of installed stirrers may be the same as or different from the number of JAS nozzles.

Another embodiment of the gas-liquid contact device of the present invention is shown in FIG. The jet 33 loses momentum after reaching the predetermined reach distance L1 as described above, and turns upward in the vertical direction as the bubbles rise. The stirrer can also be installed by lowering the rotating shaft 44 in the vertical direction from the ceiling 43 of the gas-liquid contact device so that the stirring surface 41 is parallel to the water surface 42.
When a stirrer is installed as shown in FIG. 4, a radial flow 45 is newly generated from the rotation center of the stirrer so as not to disturb the main jet of JAS, but rather to complement the area where the main jet of JAS does not reach, This becomes a circulating flow for supplying sufficient bubbles to the region 23 where the jet flow from the nozzle outlet does not reach.

  As described above, the gas-liquid contact device of the present invention has a stirrer disposed so that the stirring surface is perpendicular to the streamline of the JAS main jet. Thus, various circulation flows and the like can be generated, and the area where bubbles do not reach in the aeration tank can be remarkably reduced.

  The type of stirrer that can be employed in the gas-liquid contact device of the present invention is not particularly limited, but various types such as a turbine type, an inclined paddle, a propeller type, a paddle type, an anchor paddle type, a gate type paddle type, a ribbon type, etc. A stirrer having an impeller shape can be used. Among these, not only the stirring force in the radial direction but also a stirrer of a type in which the pushing forward is strengthened is particularly effective, and an inclined paddle is preferably used.

  The gas-liquid contact device of the present invention can be applied to a device that requires aeration, such as a desulfurization device for flue gas generated during refuse treatment, coal combustion, etc .; a device for a chemical synthesis plant such as a batch reactor for aeration of slurry. However, it can be suitably employed in a flue gas desulfurization apparatus for cleaning and desulfurizing sulfur oxide in combustion exhaust gas with an absorbent containing alkali.

One mode of the flue gas desulfurization apparatus according to the present invention is shown in FIG.
In the flue gas desulfurization apparatus 50 according to FIG. 5, the absorbing liquid 53 is sucked from the gas-liquid contact apparatus 100 according to the present invention described above and the absorbing liquid suction port 52 provided on the side wall of the aeration tank 51 of the gas-liquid contacting apparatus. A circulation pump 55 that circulates in the liquid supply pipe 54 of the gas-liquid contact device, and a spraying means 56 such as a spray nozzle that ejects the absorbing liquid and contacts the exhaust gas.
In this configuration, the circulation pump 55 circulates the absorbing liquid in the liquid supply pipe 54 and sends a part thereof to the spraying means 56 provided in the upper part of the flue gas desulfurization device. The circulating pump and the pump for feeding the liquid to the spraying means may be separate and independent.
As another aspect of the flue gas desulfurization apparatus according to the present invention, as shown in FIG. It is also possible to employ a method in which the rotating shaft 65 of the stirrer 64 is lowered from the ceiling 63 in the apparatus 60.

  The gas-liquid mixing means and the stirrer provided in the aeration tank of the flue gas desulfurization apparatus are disposed at a position away from the absorption liquid suction port. Therefore, when the aeration tank is rectangular, as shown in FIGS. 7 (a) and 7 (b), the liquid supply pipe 74 and the stirrer are usually provided on the surface 73 opposed to the aeration tank side surface 72 provided with the suction port 71 for the absorbing liquid. 75 are installed in parallel. When the aeration tank is cylindrical, as shown in FIG. 8, the JAS nozzle 74 and the stirrer 75 can be arranged on the cylindrical side wall so as to face the vicinity of the center of the bottom surface of the cylinder. As a result, it is possible to prevent fine bubbles in the jet from being sucked into the circulation pump and reducing the pump performance.

  The aeration tank preferably includes bubble blocking means such as a punching plate 76 in the vicinity of the suction port for the absorbing liquid. Thereby, the suction | inhalation of the fine bubble to the circulation pump can be prevented more reliably.

  In the flue gas desulfurization apparatus of the present invention, by adopting the gas-liquid contact apparatus of the present invention, as a result of being able to sufficiently oxidize sulfite ions generated by absorbing sulfur oxide over the entire aeration tank, It is possible to reduce sulfite ions in the absorbing solution sprayed by the spraying means, and to suppress a decrease in desulfurization performance.

  The flue gas desulfurization apparatus of the present invention has a low sulfur oxide content, and JAS can be used to treat combustion exhaust gas that can supply a sufficient amount of oxygen for oxidation to the liquid reservoir even if the number of JAS is small. It is not necessary to install an excessive number of JAS, and the number of JAS to be installed is reduced, so that an increase in power consumption of a circulation pump for supplying the absorbing liquid to the JAS at a predetermined pressure can be suppressed.

Example 1
As shown in FIG. 7, a wet flue gas desulfurization apparatus equipped with a single-chamber absorption tower has a concentration of 30% by mass containing limestone (calcium carbonate) having a concentration of 50 mmol / l up to a height of 5 m in a tank having a width of 21 m and a depth of 9.9 m. The gypsum slurry was stored. Next, seven JAS (nozzle diameter 150A, flow path narrow portion diameter 110 mm) are provided at equal intervals on the tank wall having a width of 21 m so that the jet port faces the bottom of the tank, and the blade diameter 1 is 3 m above the center of the JAS nozzle. Three turbine-type stirrers of 6 m were arranged at intervals of 6 m so that the stirring surface was perpendicular to the nozzle opening of JAS. In addition, a suction port was provided at the lower part of the wall facing the wall where JAS was installed.
The aqueous solution in the tank was pumped from the suction port by pump suction, and a part of the pumped solution was blown up from a spray nozzle provided in the upper pipe of the tank, thereby contacting SOx with an exhaust gas having a SOx concentration of 500 ppm. On the other hand, a part of the aqueous solution not used for absorbing the exhaust gas was circulated to the JAS liquid supply pipe, and the aqueous solution containing air bubbles was jetted into the tank at a jet flow distance of 6 m. The pump power was set so that the liquid flow rate per JAS was 470 m ³ / h and the air flow rate per JAS was 230 m ³ / h.

Example 2
As shown in FIG. 6, gypsum slurry having a concentration of 30% by mass containing limestone (calcium carbonate) having a concentration of 50 mmol / l was stored in a tank having a width of 21 m and a depth of 20 m of a wet flue gas desulfurization apparatus equipped with a two-chamber absorption tower. Seven narrow channel diameters (110 mm) were provided at equal intervals. In addition, a pump suction is provided at the bottom of the wall facing the wall where JAS is installed, and the stirrer is a turbine-type stirrer having a blade diameter of 1.6 m from the tank ceiling with an 8 m interval so that the stirring surface is parallel to the water surface. Two units were arranged. Two agitators were provided at a position 10 m away from the tip of the JAS nozzle.
The aqueous solution in the tank was pumped from the suction port by pump suction, and a part of the pumped solution was blown up from a spray nozzle provided in the upper pipe of the tank, thereby contacting SOx with an exhaust gas having a SOx concentration of 500 ppm. On the other hand, a part of the aqueous solution not used for absorbing the exhaust gas is circulated to the JAS liquid supply pipe,
An aqueous solution containing air bubbles was jetted into the tank at a jet distance of 6 m.

  In Example 1 and Example 2, the density | concentration of the sulfite ion in a pump suction liquid was compared with the case where a stirrer was drive | operated (rotation speed 30rpm) and the case where it was not drive | operated. The concentration of sulfite ion was measured by iodometry after sampling the slurry. The results are shown in Table 1.

表１から、実施例１および２のいずれの設置形態であっても、亜硫酸イオン濃度が低下しており、噴流に対して所定の方向へ攪拌基を設置することにより、攪拌による気液接触性能が向上していることがわかった。

From Table 1, in any of the installation forms of Examples 1 and 2, the sulfite ion concentration is reduced, and by installing a stirring base in a predetermined direction with respect to the jet, gas-liquid contact performance by stirring Was found to have improved.

FIG. 1 is a schematic diagram showing a streamline of a jet flow of a JAS nozzle. FIG. 2 is a diagram showing a region where there are few bubbles when only the JAS nozzle is used. FIG. 3 is a schematic plan view (a) and a schematic side view (b) showing one embodiment of the installation position of the stirrer in the gas-liquid contact device of the present invention. FIG. 4 is a schematic plan view (a) and a schematic side view (b) showing one embodiment of the installation position of the stirrer in the gas-liquid contact device of the present invention. FIG. 5 is a schematic diagram showing an overall outline of the flue gas desulfurization apparatus of the present invention. FIG. 6 is a schematic view showing a two-column type flue gas desulfurization apparatus as one aspect of the flue gas desulfurization apparatus of the present invention. FIG. 7 is a schematic plan view (a) and a schematic side view (b) showing an example of an installation mode of gas-liquid mixing means in the flue gas desulfurization apparatus of the present invention. FIG. 8 is a schematic plan view showing an example of an installation mode of gas-liquid mixing means in the flue gas desulfurization apparatus of the present invention. FIG. 9 is a schematic cross-sectional view showing the internal structure and configuration of the gas-liquid mixing means. FIG. 10 is a schematic plan view showing the arrangement of JAS nozzles in a conventional flue gas desulfurization apparatus.

Explanation of symbols

1 Gas-liquid contact device 10, 51, 100 Aeration tank 11, 32 Gas-liquid mixing means (JAS nozzle)
12, 33 Jets 21a, b, c Flow 22 Aeration tank side walls 23, 24 Areas with few bubbles 31, 64, 75 Stirrer 34, 45 Radial flow 35 Rotary flow 36, 41 Stirring surface 42 Water surface 43 Ceiling 44, 65 Rotating shafts 50, 60, 70 Flue gas desulfurization devices 52, 71 Suction port 53 Alkali absorbing liquids 54, 74 Liquid supply pipe 55 Circulating pump 56 Dispersing means 61 Cocurrent gas tower 62 Counterflow gas tower 63 Ceiling 72 Aeration tank side face 73 Surface 76 Punching plate 91 Channel narrow portion 92 Liquid supply piping 93 Opening portion 94 Gas supply piping 95 Negative pressure region 96 Gas 101 JAS

Claims (4)

A gas-liquid contact device comprising an aeration tank and a gas-liquid mixing means having a nozzle tip penetrating the side wall of the aeration tank,
The gas-liquid mixing means includes a liquid supply pipe in which a channel narrow portion is formed and an opening for pipe connection is provided downstream of the channel narrow portion, and a gas supply inserted into the opening of the liquid supply pipe A pipe, and by flowing the liquid into the liquid supply pipe, a negative pressure is generated in the vicinity of the opening downstream of the narrow portion of the flow path so that the gas can be sucked and dispersed in the liquid from the opening. And
In a position higher than the nozzle tip of the gas-liquid mixing means, Bei give a stirrer vertically directly above the nozzle of the gas-liquid mixing means,
The agitator at a position higher than the gas-liquid mixing means, said agitator stirring surface and the gas-liquid mixture the nozzle gas-liquid contact apparatus and direction are disposed to be perpendicular to faces of means. A gas-liquid contact device comprising an aeration tank and a plurality of gas-liquid mixing means having nozzle tips penetrating the side wall of the aeration tank,
The gas-liquid mixing means includes a liquid supply pipe in which a channel narrow portion is formed and an opening for pipe connection is provided downstream of the channel narrow portion, and a gas supply inserted into the opening of the liquid supply pipe A pipe, and by flowing the liquid into the liquid supply pipe, a negative pressure is generated in the vicinity of the opening downstream of the narrow portion of the flow path so that the gas can be sucked and dispersed in the liquid from the opening. And
In a position higher than the nozzle tip of the gas-liquid mixing means, a stirrer is provided at a position between the nozzles of the gas-liquid mixing means arranged in parallel with the side wall of the aeration tank,
A gas-liquid contact device in which the stirrer is installed at a position higher than the gas-liquid mixing means so that a stirring surface of the stirrer is perpendicular to a direction of the nozzle of the gas-liquid mixing means. The gas-liquid contact device according to claim 1 or 2 , wherein the stirrer is an inclined paddle. A flue gas desulfurization device for cleaning and desulfurizing sulfur oxides in combustion exhaust gas with an absorbent containing alkali,
The gas-liquid contact device according to any one of claims 1 to 3 ,
A circulation pump for sucking the absorbing liquid from the suction port of the absorbing liquid provided in the aeration tank of the gas-liquid contact device and circulating it to the liquid supply pipe of the gas-liquid contact device;
A flue gas desulfurization device comprising spraying means for bringing the absorbing liquid into contact with the flue gas.

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