JP2010167330A - Wet two-stage desulfurization equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain wet two-stage desulfurization equipment that suitably disposes an absorbent spray nozzle in a venturi scrubber, can efficiently absorb and remove micro ingredients such as mercury components and fluorine components, and has a low-powered venturi scrubber. <P>SOLUTION: The wet two-stage desulfurization equipment that processes sulfur oxide in a tail gas includes an absorption tower 1 where a channel in which the tail gas is allowed to flow downwardly along the flowing direction of the tail gas is disposed at the advanced venturi scrubber (AVS) 2 that atomizes the absorbent provided in the channel of the tail gas discharged from a combustion apparatus containing a boiler, a throat section S narrower than other channels in the channel is provided, spray nozzles (hereinafter referred to as nozzles) 3 that atomize the absorbent onto the wall surface of the throat section S along the flowing direction of the tail gas are disposed in a plurality of stages, the adjacent nozzles 3 thereto are mutually disposed staggered, the nozzles 3 on lower stage sides out of a plurality of the nozzles 3 are disposed to atomize the absorbent more downwardly than the nozzles 3 on upper stage sides, and the nozzles 3 that atomize the absorbent are provided in a tail gas channel downstream AVS2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment device that removes harmful components in exhaust gas, and in particular, a wet type equipped with an advanced venturi scrubber that can efficiently remove trace components such as mercury and fluorine compounds and greatly reduce the power of the desulfurization device. The present invention relates to a two-stage flue gas desulfurization apparatus.

FIG. 12 shows an absorption tower in a conventional wet flue gas desulfurization apparatus.
This wet flue gas desulfurization apparatus is mainly composed of an absorption tower body 1, an inlet duct 1a, an outlet duct 1b, a circulation tank 16, an absorbing liquid circulation pump 17, a spray nozzle 21, a mist eliminator 22, and the like.

  Exhaust gas discharged from a boiler (not shown) is introduced from the inlet duct 1a of the absorption tower main body 1 into the main body in a substantially horizontal direction by a desulfurization fan (not shown) and discharged from an outlet duct 1b provided at the top of the tower. The During this time, the absorption liquid containing calcium carbonate in the circulation tank 16 below the absorption tower body 1 is sent to the spray header 20 via the circulation pipe 18 by the circulation pump 17 provided in the circulation pipe 18. Are sprayed from a plurality of spray nozzles 21.

In the absorption tower main body 1, the absorption liquid selectively absorbs SO ₂ in the exhaust gas by gas-liquid contact between the absorption liquid injected from the spray nozzle 21 and the exhaust gas. The absorbing solution that has absorbed SO ₂ once accumulates in the circulation tank 16 and is oxidized by oxygen in the air supplied into the circulation tank 16 to generate calcium sulfate (gypsum). A part of the absorption liquid in the circulation tank 16 in which calcium carbonate and gypsum coexist is sent again to the spray nozzle 21 by the absorption liquid circulation pump 17, and a part is sent to a waste liquid treatment / gypsum recovery system (not shown). Of the absorbing liquid atomized from the absorbing liquid from the spray nozzle 21, those having a small droplet diameter are accompanied by the exhaust gas, but are collected by the mist eliminator 22 provided in the outlet duct 1b. .

This wet flue gas desulfurization apparatus can absorb and remove not only SO ₂ in exhaust gas but also trace components such as mercury (particularly molecular mercury such as mercury chloride) and fluorine compound (particularly hydrogen fluoride). In particular, since mercury chloride, hydrogen fluoride, and the like have high absorbability in water, a removal rate equal to or higher than that of SO ₂ can be obtained. However, in order to comply with strict emission regulations in the United States, it is required to remove the trace components at a high removal rate of about 95 to 99.9%, which is more than the amount of circulating absorbent liquid required for SO ₂ removal. A large amount of circulating fluid is required, and the power of the desulfurization apparatus is greatly increased.
Further, a configuration is known in which an advanced venturi scrubber having a spray nozzle for spraying an absorbing liquid provided on an exhaust gas flow channel wall surface provided in an exhaust gas flow channel for flowing exhaust gas discharged from a combustion device downward is known.

JP 2003-260326 A

  Among the above prior arts, the venturi scrubber was designed mainly for dust removal, so no consideration was given to gas absorption and removal, and an efficient arrangement of absorbing liquid spray nozzles for dust removal and gas absorption and removal was made. There was a problem that not.

Further, unlike the arrangement of the absorbing liquid spray nozzle in the small-scale flue gas treatment apparatus that has been applied in the prior art, the wall surface of the conventional venturi scrubber applied to a large-scale flue gas treatment apparatus such as an 800 to 1000 MW class boiler. There is a problem that the liquid droplets sprayed from the absorbing liquid spray nozzle provided in the nozzle cannot be sprayed uniformly on the horizontal section of the venturi scrubber.
Further, in the configuration in which the advanced venturi scrubber is provided to remove dust in the exhaust gas, removal of trace components contained in the boiler exhaust gas has not been considered.

  An object of the present invention is to provide a wet two-stage desulfurization apparatus having a low-powered venturi scrubber with a highly efficient arrangement of an absorption liquid spray nozzle of a venturi scrubber and capable of absorbing and removing trace components such as mercury components and fluorine components with high efficiency. There is to get.

The problems of the present invention are solved by the following means.
According to the first aspect of the present invention, an advanced venturi scrubber having a spray nozzle for spraying an absorbing liquid is provided in a flow path of exhaust gas discharged from a combustion apparatus including a boiler, and the absorbing liquid is provided in an exhaust gas flow path downstream of the advanced venturi scrubber. In a wet two-stage desulfurization apparatus for treating sulfur oxides in exhaust gas provided with an absorption tower having a spray nozzle for spraying the advanced venturi scrubber, the advanced venturi scrubber has a flow path for circulating the exhaust gas downward along the exhaust gas flow direction. A throat portion having a narrower width than the width of the other flow passage is provided in the flow passage, and a plurality of spray nozzles for spraying the absorbent on the wall surface of the throat portion are arranged along the exhaust gas flow direction. The spray nozzles that are adjacent in the horizontal direction and the gas flow direction are arranged in a staggered manner, and the lower-stage spray nozzles in the plurality of spray nozzles are arranged. Renozuru a wet two-stage desulfurization apparatus absorbing liquid downward is arranged to spray from the spray nozzle of the upper side.

  The invention according to claim 2 is the wet two-stage desulfurization apparatus according to claim 1, wherein the spray angle of the upper spray nozzle of the venturi scrubber is narrower than the spray angle of the lower spray nozzle.

  Invention of Claim 3 is a wet two-stage desulfurization apparatus of Claim 1 or 2 which installs the spray nozzle of a venturi scrubber in the hollow part provided in the gas flow-path wall surface of a venturi scrubber.

  According to a fourth aspect of the present invention, the tip of the lower spray nozzle of the venturi scrubber is arranged along the gas flow path wall surface of the venturi scrubber, and the lower spray nozzle is arranged in the vertical direction perpendicular to the plane formed by the wall surface of the venturi scrubber. The wet two-stage desulfurization apparatus according to claim 3, wherein the apparatus is arranged so as to spray droplets in a direction inclined by (180 ° -θ °) / 2 (θ °: spray angle) in a horizontal direction with respect to the plane. is there.

(Function)
According to the invention of claim 1, a venturi scrubber having both functions of gas absorption removal and inertial collision removal is installed on the upstream side of the desulfurization absorption tower, and not only dust removal by inertial collision that a conventional venturi scrubber has, It is possible to efficiently absorb and remove trace components (including mercury components, sulfuric acid mist, and dust) in the exhaust gas under high gas flow rate conditions where high absorption and removal performance can be obtained. In addition, the spray nozzles in the venturi scrubber are arranged in multiple stages, all the spray nozzles are arranged in the throat part, which is the throttle part of the venturi scrubber, and the direction of liquid droplet spraying from the lower spray nozzle is changed to the liquid droplet spraying from the upper spray nozzle. By disposing downward from the direction, the upper spray nozzle has a function of removing inertial collisions than the lower spray nozzle and is superior in removing fine particles (dust, sulfuric acid mist, etc.).

  Further, the spray droplets sprayed from the upper spray nozzle can prevent the gas at the center of the throat portion from being blown out. Furthermore, the lower spray nozzle is superior in gas absorption removal of trace components (mercury, fluorine compounds, etc.) contained in the boiler exhaust gas by spraying droplets downward from the upper spray nozzle.

  In this way, all the spray nozzles can be installed in the throat portion to prevent the gas from blowing through. By spraying the liquid droplets downward from the lower spray nozzle, the pressure loss of the gas flow can be reduced as compared with the conventional venturi scrubber in which the spray nozzles spraying the liquid droplets in the horizontal and upward directions are arranged.

  Furthermore, spray nozzles are arranged in a staggered manner on the same horizontal plane facing each other, and the triangular gaps created between the spray nozzles and the spray nozzles can be covered by spray droplets from the respective opposing wall surfaces. Blow-through can be prevented. Further, the adjacent lower spray nozzles are also arranged in a staggered manner with respect to the upper spray nozzles, thereby preventing gas blow-through.

  According to the first aspect of the present invention, the spray nozzle for spraying the absorbent on the wall surface of the throat portion of the venturi scrubber provided on the upstream side of the desulfurization absorption tower is arranged in a plurality of stages along the exhaust gas flow direction, and the horizontal direction and gas Adjacent spray nozzles in the flow direction are arranged in a staggered manner, and the lower spray nozzles in the plurality of spray nozzles are disposed so that the absorbing liquid sprays downward from the upper spray nozzles, thereby preventing gas blow-through. It can prevent and reduce the pressure loss of gas flow, and furthermore, highly efficient removal of fine particles (such as dust and sulfuric acid mist) and trace components (including mercury component, sulfuric acid mist and dust) in exhaust gas is possible. And a low-power flue gas treatment system.

  In addition, with the increase in performance by the venturi scrubber having the above-described configuration, it is possible to prevent a significant increase in the amount of the circulating liquid in the desulfurization absorption tower. As a result, it is possible to minimize an increase in circulation pump power. Furthermore, the fan power can be reduced by reducing the pressure loss of the venturi scrubber.

  According to the invention of claim 2, by arranging the spray angle of the upper spray nozzle on the same wall surface to be narrower than the spray angle of the lower spray nozzle, the central portion of the venturi scrubber and the opposing wall surface The droplet density can be increased and gas blow-off can be prevented. Furthermore, by arranging the lower spray nozzle at a wider angle than the upper spray nozzle, it is possible to cover the gas blow-off in the vicinity (near the wall surface) of the upper spray nozzle.

  According to the third aspect of the invention, by attaching the spray nozzle of the venturi scrubber on the inner side of the wall surface of the venturi scrubber, it is possible to prevent the gas from blowing through in the vicinity of the nozzle of the venturi scrubber (near the wall surface).

  According to the fourth aspect of the present invention, the tip of the lower spray nozzle of the venturi scrubber is disposed along the venturi scrubber wall surface, and the lower spray nozzle is arranged with respect to a vertical plane perpendicular to the plane formed by the wall of the venturi scrubber. By tilting in the horizontal direction by (180 ° −θ °) / 2 (θ °: spray angle), it is possible to prevent gas blow-off near the nozzle (near the wall surface) of the venturi scrubber.

It is a side view of the wet two-stage desulfurization apparatus which installed the advanced venturi scrubber in the upstream of the desulfurization absorption tower of one Example by this invention. 1 is a detailed view of an advanced venturi scrubber of Example 1. FIG. It is a B-B 'arrow line view in the advanced venturi scrubber of FIG. It is a B-B 'arrow line view in the advanced venturi scrubber in FIG. 2 of Example 2. FIG. FIG. 5 shows the spray angle θ1 ° of the upper spray nozzle shown in FIG. FIG. 6 is a C-C ′ arrow view of the advanced venturi scrubber in FIG. 2 of the second embodiment. FIG. 7 shows the spray angle θ2 ° of the lower spray nozzle shown in FIG. It is a detailed view of the advanced venturi scrubber of Example 3. It is a B-B 'arrow line view in the advanced venturi scrubber of FIG. It is detail drawing of the advanced venturi scrubber of Example 4. It is a C-C 'arrow line view in the advanced venturi scrubber of FIG. It is the figure which showed the wet desulfurization apparatus of the prior art.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a wet two-stage desulfurization apparatus according to this embodiment, and an advanced venturi scrubber 2 is installed on the upstream side of the desulfurization absorption tower body 1. FIG. 2 shows a detailed view of the advanced venturi scrubber 2 in FIG. FIG. 3 shows a B-B ′ arrow view of the advanced venturi scrubber 2 of FIG. 2.

  The wet two-stage desulfurization apparatus of this embodiment shown in FIGS. 1 to 3 is conventional in that an advanced venturi scrubber 2 having both functions of gas absorption removal and inertial collision removal is installed on the upstream side of the desulfurization absorption tower body 1. Different from technology.

  The structure of the desulfurization absorption tower is the same as that of the wet flue gas desulfurization apparatus of the prior art shown in FIG. 12, the absorption tower body 1, the inlet duct 1a, the outlet duct 1b, the circulation tank 16, the absorption liquid circulation pump 17, the spray nozzle 21, It consists of a mist eliminator 22 and the like.

Next, the configuration of the advanced venturi scrubber (hereinafter abbreviated as AVS) 2 will be described.
The exhaust gas introduced from the upper side to the lower side of the AVS 2 is directed horizontally and obliquely downward from the spray nozzle 3 attached to the wall surface of the AVS 2 where the cross-sectional area of the flow path is smaller than the area of the cross-sectional area of the other part. In contact with the absorbing liquid 6 to be sprayed, trace components such as mercury and fluorine compounds in the exhaust gas are absorbed and removed.
Further, the liquid sprayed from the spray nozzle 3 passes through the downcomer 4 and is stored in the tank 5. The absorbing liquid 6 in the tank 5 is sent to the spray nozzle 3 through a circulation pipe 8 by a pump 7.

  As shown in FIG. 3, the spray nozzle 3 for spraying the absorbing liquid 6 is installed on the inner wall surface on the same horizontal surface of the channel wall surface of the AVS 2, and one channel inner wall surface and the other channel of the AVS 2 that face each other. The spray nozzles 3 are arranged in a staggered manner on the inner wall surface. Absorbing liquid droplets sprayed from the opposing surface of the inner wall of the flow path are supplied to the triangular gap formed between the adjacent spray nozzles 3 and 3. Therefore, gas can be prevented from being blown through the gap.

  Further, the spray nozzles 3 and 3 are arranged in a multi-stage in the vertical direction on the same wall surface of the AVS 2, so that the gas blown easily between the two nozzles 3 and 3 adjacent in the vertical direction is prevented from flowing downstream. Can be reliably covered by drops.

  Further, as shown in FIG. 2, the upper spray nozzle 3 has a higher relative velocity between the fine particles contained in the boiler exhaust gas and the spray droplets 9 than the lower spray nozzle 3, and thus has an inertial collision removal function. And sulfuric acid mist). Further, since the spray droplet 9 sprayed from the upper spray nozzle 3 has a higher moving speed in the horizontal direction than the spray droplet 9 sprayed from the lower spray nozzle 3, the liquid at the center of the throat portion S (FIG. 2). Drop density can be increased and gas blow-out can be prevented. Further, since the lower spray nozzle 3 adjacent in the vertical direction sprays the spray droplet 9 downward from the upper spray nozzle 3, the spray droplet 9 from the spray nozzle 3 on one wall surface is opposed to the venturi scrubber 2. The residence time to the wall surface is long, and it is excellent in absorbing and removing gas components such as mercury and fluorine compounds contained in boiler exhaust gas.

  Since all the spray nozzles 3 are attached in the region of the throat portion S, the inside of the throat portion S of the venturi scrubber 2 can have a high liquid density, and gas blow-out can be prevented. Since the lower spray nozzle 3 is attached in a direction in which the spray droplet 9 can be sprayed downward, the pressure loss is lower than that of the venturi scrubber 2 in which the spray nozzle 3 for spraying the spray droplet 9 in the horizontal direction and upward is disposed. Can be reduced.

  A second embodiment of the present invention is shown in FIGS. The present embodiment further enhances the operational effects of the first embodiment. 4 shows that the spray angle θ1 ° of the upper spray nozzle 3 provided on the wall surface of the venturi scrubber 2 shown in FIG. 1 is narrower than the spray angle θ2 ° of the adjacent lower spray nozzle 3 (θ1 ° <θ2 °). FIG. 3 is a view taken along the line BB ′ of FIG. 5 shows a spray angle θ1 ° of the upper spray nozzle 3 shown in FIG. 4, and FIG. 6 shows a CC ′ arrow view of the advanced venturi scrubber in FIG. FIG. 7 shows the spray angle θ2 ° of the spray nozzle 3 on the lower side of FIG.

  By making the spray angle θ1 ° of the upper spray nozzle 3 shown in FIG. 4 smaller than the spray angle θ2 ° of the lower spray nozzle 3 shown in FIG. 6, the central portion of the venturi scrubber 2 and the wall surface on which the spray nozzle 3 is installed are arranged. It is possible to increase the droplet density on the opposing wall surface. In the lower spray nozzle 3 shown in FIG. 6, since the spray angle θ2 ° is relatively large, the droplet density in the vicinity of the spray nozzle 3 can be increased, and gas blowout in the vicinity of the upper spray nozzle 3 can be covered. it can.

  A third embodiment of the present invention is shown in FIGS. This embodiment further enhances the effect of preventing gas blow-through of the second embodiment shown in FIG. FIG. 8 is a detailed view of the venturi scrubber 2 shown in FIG. The example which becomes is shown. FIG. 9 shows a B-B ′ arrow view of the venturi scrubber 2 of FIG. 8.

The spray nozzle 3 is attached by attaching a cylindrical or square protrusion and flange to the venturi scrubber 2 so that the spray nozzle 3 can be attached to the recess 2 a provided on the wall surface of the venturi scrubber 2.
In this embodiment, the effect of preventing gas blow-off by increasing the droplet density on the wall surface of the venturi scrubber 2 is excellent.

  A fourth embodiment of the present invention is shown in FIGS. FIG. 10 is a detailed view of the venturi scrubber 2 shown in FIG. 1, in which the upper and lower spray nozzles 3 and 3 are respectively provided in the recess 2a of the wall surface of the venturi scrubber 2, and the tip of the lower spray nozzle 3 is connected to the venturi. It is the example arrange | positioned along the wall surface of the scrubber 2. FIG. FIG. 11 shows a C-C ′ arrow view of the venturi scrubber 2 of FIG. 10. Further, the lower spray nozzle 3 is tilted horizontally (180-θ °) / 2 (θ °: spray angle) with respect to the vertical plane perpendicular to the plane formed by the wall surface of the venturi scrubber 2 so that the same horizontal plane is obtained. The spray droplets 9 are sprayed into the triangular gap formed between the adjacent spray nozzles 3 and 3 to prevent the gas from being blown out.

  By combining FIGS. 4 to 11 based on the configuration shown in FIGS. 1 to 3, it is possible to prevent the gas from being blown out, and to make a smoke treatment system having the venturi scrubber 2 with high efficiency and low power.

  Since the two-stage desulfurization system according to the present invention can contribute to prevention of mercury re-release in the desulfurization apparatus, the industrial applicability is high.

DESCRIPTION OF SYMBOLS 1 Absorption tower body 1a Inlet duct 1b Outlet duct 2 Advance venturi scrubber 2a Indentation part 3 Spray nozzle 4 Precipitation pipe 5 Tank 6 Absorbing liquid 7 Pump 8 Circulating pipe 9 Spray droplet 16 Circulating tank 17 Absorbing liquid circulation pump 18 Circulating pipe 20 Spray header 21 Spray nozzle 22 mist eliminator

Claims (4)

An absorption tower having an advanced venturi scrubber having a spray nozzle for spraying an absorbing liquid in a flow path of exhaust gas discharged from a combustion apparatus including a boiler, and having a spray nozzle for spraying the absorbing liquid to an exhaust gas flow path downstream of the advanced venturi scrubber In a wet two-stage desulfurization apparatus for treating sulfur oxides in exhaust gas provided with
The advanced venturi scrubber has a flow path for flowing the exhaust gas downward along the flow direction of the exhaust gas, and in the flow path, a throat portion made of a flow path having a width narrower than the width of the other flow path is provided. A plurality of spray nozzles for spraying the absorbing liquid on the wall surface of the throat portion are arranged along the exhaust gas flow direction, and spray nozzles adjacent in the horizontal direction and the gas flow direction are arranged in a staggered manner in the plurality of spray nozzles. A wet two-stage desulfurization apparatus characterized in that the lower spray nozzle is arranged so that the absorbing liquid sprays downward from the upper spray nozzle.   2. The wet two-stage desulfurization apparatus according to claim 1, wherein the spray angle of the upper spray nozzle of the venturi scrubber is made narrower than the spray angle of the lower spray nozzle.   The wet two-stage desulfurization apparatus according to claim 1 or 2, wherein the spray nozzle of the venturi scrubber is installed in a hollow portion provided on a gas flow path wall surface of the venturi scrubber.   The tip of the spray nozzle on the lower side of the venturi scrubber is arranged along the gas flow passage wall surface of the venturi scrubber, and the spray nozzle on the lower stage is placed in a horizontal direction with respect to the vertical plane perpendicular to the plane formed by the wall surface of the venturi scrubber ( The wet two-stage desulfurization apparatus according to claim 3, wherein the wet two-stage desulfurization apparatus is arranged to spray droplets in a direction inclined by 180 ° -θ °) / 2 (θ °: spray angle).

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