WO2014156985A1

WO2014156985A1 - Seawater flue-gas desulfurization device and method for operating same

Info

Publication number: WO2014156985A1
Application number: PCT/JP2014/057825
Authority: WO
Inventors: 石坂　浩; 中本　隆則; 浩之野坂; 片川　篤; 今田　典幸; 佐々木　郷紀
Original assignee: バブコック日立株式会社
Priority date: 2013-03-26
Filing date: 2014-03-20
Publication date: 2014-10-02
Also published as: PH12015501897B1; PH12015501897A1; JP2014188406A; SA515361204B1; MY173551A

Abstract

A seawater flue-gas desulfurization device provided with an absorption tower (1) and an oxidation tank (14). Said absorption tower (1) is provided with the following: dust-removal spray nozzles (8) that repeatedly supply seawater from a circulation tank (5) so as to absorb or catalytically remove soot and heavy metals from an exhaust gas; desulfurization spray nozzles (9), above the dust-removal spray nozzles (8), that spray fresh seawater so as to absorb and thereby remove SO_x from the exhaust gas; and two or more collectors (10), laid out in a staggered pattern between the nozzles (8 and 9), that collect all of the seawater sprayed by the desulfurization spray nozzles (9). All of the seawater sprayed by the desulfurization spray nozzles (9) is collected by the collectors (10) and oxidized in the abovementioned oxidation tank (14). In this seawater flue-gas desulfurization device, a flow-control member (22) that controls the flow of the sprayed seawater is laid out between the collectors (10) and the desulfurization spray nozzles (9) and a mist eliminator (23) is laid out between the collectors (10) and the dust-removal spray nozzles (8) so as to prevent any liquid from passing between an absorption section (A) of the absorption tower (1), which contains the desulfurization spray nozzles (9) and removes SO_x from the exhaust gas, and a dust-removal section (B) of the absorption tower (1), which contains the dust-removal spray nozzles (8) and removes soot and heavy metals from the exhaust gas. The treatment load associated with purifying contaminated seawater in the dust-removal section (B) is thus reduced.

Description

Seawater flue gas desulfurization equipment and its operation method

The present invention relates to a flue gas treatment apparatus for removing sulfur oxides of harmful components in exhaust gas generated from a combustion apparatus such as a boiler installed in a thermal power plant or factory, and in particular, seawater is used as a desulfurization absorption liquid. The present invention relates to a seawater flue gas desulfurization apparatus and its operation method.

As a flue gas desulfurization device in a thermal power plant, a seawater wet desulfurization device that uses seawater may be used in overseas coastal areas, particularly in Southeast Asia. The cost of equipment can be reduced by a seawater desulfurization method in which seawater is used as an absorbing solution for sulfur oxide in exhaust gas, the seawater after absorbing sulfur oxide is aerated, and then discharged into the ocean.

Fig. 4 shows the system of a wet flue gas desulfurization system using seawater of the prior art. A wet flue gas desulfurization apparatus similar to the wet flue gas desulfurization apparatus using seawater shown in FIG. 4 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-234334 (Patent Document 1).

This wet desulfurization apparatus is mainly composed of a desulfurization absorption tower 100 for treating sulfur oxide (SOx) in combustion exhaust gas discharged from a boiler, an inlet duct 102 for introducing exhaust gas into the desulfurization absorption tower 100, and a desulfurization absorption tower 100 for SOx. The exhaust duct 103 for discharging the treated exhaust gas, the desulfurization (seawater) spray nozzle 109 for spraying the absorbing liquid (seawater) that absorbs SOx in the exhaust gas onto the exhaust gas, and the fine droplets (mist) accompanying the flow of the exhaust gas Mist eliminator 107 to be removed, oxidation tank 114 for oxidizing sulfurous acid generated by absorption of SOx, oxidation air blower 116 for sending air to be supplied to the oxidation tank 114, and air diffused for jetting air sent by the oxidation air blower 116 It consists of a nozzle 117 and the like.

Combustion exhaust gas discharged from a boiler (not shown) is introduced from the inlet duct 102 into the desulfurization absorption tower 100 in a substantially horizontal direction by a desulfurization fan (not shown) and discharged from an outlet duct 103 provided at the top of the desulfurization absorption tower 100. .

Seawater heated by a boiler condenser (not shown) is sent to the uppermost stream portion of the oxidation tank 114 via the dilution seawater feed pipe L3, and a part of the seawater is pumped up by the seawater pump 118 to be absorbed by the seawater. Sprayed as fine droplets from the desulfurization spray nozzle 109 through the water pipe L2, and gas-liquid contact between the seawater and the exhaust gas is performed, so that dust, hydrogen chloride (HCl), hydrogen fluoride (HF), etc. in the exhaust gas In addition to the acidic gas, SOx, mainly SO2, in the exhaust gas is selectively absorbed and removed on the surface of the absorbing droplets of the desulfurization spray nozzle 109.

In the seawater atomized by spraying from the desulfurization spray nozzle 109, mist accompanying the flow of the exhaust gas is collected by a mist eliminator 107 installed in the outlet duct 103 at the top of the desulfurization absorption tower 100. The exhaust gas that has passed through the mist eliminator 107 is reheated as necessary, and then discharged into the atmosphere from a chimney (not shown).

The seawater that has absorbed SO2 in the exhaust gas becomes sulfite ion-containing seawater and is extracted from the desulfurization absorption tower 1 by the sulfite ion-containing seawater pipe L4 and sent to the oxidation tank 114. Here, the sulfite ion-containing seawater is oxidized by oxygen dissolved from the air (bubbles) sent from the oxidation air blower 116 and ejected from the aeration nozzle 117 while being diluted by the dilution seawater sent from the dilution seawater water pipe L3. And returned to the ocean 12 as treated seawater.

This conventional seawater wet desulfurization apparatus has the advantage that there is no need to provide a limestone supply facility and a gypsum recovery facility as in the limestone-gypsum method, and the cost of the desulfurization system can be kept low.

However, in addition to sulfur oxides such as SO2, the exhaust gas contains soot and heavy metals such as mercury that could not be removed by a dust collector (not shown) and is absorbed and removed by the absorption tower 100 in the same manner as SO2. Therefore, it will be discharged | emitted by the ocean 12 with the process seawater processed by the oxidation tank 114, and it may become a cause of ocean pollution. *

FIG. 2 of Patent Document 2 (Japanese Patent Application Laid-Open No. 2001-170444) divides an empty tower part of an absorption tower having an absorption liquid storage part in which an absorption liquid containing limestone is stored at the lower part into upper and lower stages by a collector, The lower stage is configured as a lower absorbent section having a lower spray nozzle that sprays exhaust gas containing limestone circulated and supplied from the absorbent storage section, and the upper stage is an upper absorbent section provided with an upper spray nozzle that sprays seawater. It is disclosed. Part of the used seawater that has come into contact with the exhaust gas in the upper absorption part is collected by the collector and discharged to the outside of the absorption tower, and the used absorption liquid collected in the absorption liquid storage part is replenished with limestone while being replenished in the lower absorption part. Sprayed from the lower spray nozzle and used to absorb exhaust gas.

In Patent Document 3 (Japanese Patent Application Laid-Open No. 2008-200699), when desulfurizing exhaust gas by flowing seawater from the upper part of the desulfurization tower and raising the exhaust gas from the lower part to the upper part of the absorption tower, The structure which suppresses the drift of the seawater in the desulfurization tower and the blow-off of exhaust gas by partitioning the horizontal cross-sectional area into a plurality is disclosed.

Further, Japanese Patent Application No. 2012-279808, which is a patent application filed on December 21, 2012 by the present applicant, proposes an exhaust gas treatment apparatus using seawater as shown in FIG. In the exhaust gas treatment apparatus shown in FIG. 5, a desulfurization spray nozzle 109 for spraying seawater is installed at the upper part of the desulfurization absorption tower 100, and a partition wall 141 is installed at the lower part of the desulfurization absorption tower 100 to form the inlet side gas flow path 102. In addition, a dust removal spray nozzle 108 for spraying seawater in the circulation tank 103 below the absorption tower to absorb and remove sulfur oxides and dust in the exhaust gas is installed in the inlet side gas flow path 102, and further, the upper stage of the dust removal spray nozzle 108 is installed. Is provided with a spray nozzle 143 for cleaning the dust spray nozzle 108. By installing a partition wall 141 in the lower part of the desulfurization absorption tower 100 and narrowing the exhaust gas flow path on the inlet side of the absorption tower, the speed of the exhaust gas introduced into the desulfurization absorption tower 100 is increased, so that a smaller amount of seawater is removed from the dust removal spray nozzle 108. It is possible to improve the dust removal efficiency by spraying.

The collector 122 is arranged between the desulfurization spray nozzle 109 and the cleaning spray nozzle 143 of the absorption tower 100 shown in FIG. 5, and a part of the seawater sprayed from the desulfurization spray nozzle 109 is collected by the collector 122 and discharged into the sea. It is.

In addition, as shown in FIG. 6 in Patent Document 4 (Japanese Patent Laid-Open No. 61-259730), the absorption tower 100 is used as a flue gas desulfurization apparatus that uses an absorbent containing limestone without using seawater, and a dust removing section B at the lower stage. A configuration is shown in which a collector 122 that collects the absorbent after spraying is provided separately in the upper absorption part A.

Absorption tower provided with dust removal part circulation tank 103 storing absorption liquid is divided into two upper and lower stages by collector 122, and the upper stage is absorption tower provided with spray nozzle 121 for spraying absorption liquid containing limestone to exhaust gas The absorption section A is the absorption tower dust removal section B in which the absorption liquid from the circulation tank 103 circulates, and the absorption liquid after contacting the exhaust gas collected by the collector 122 is provided separately from the circulation tank 103. A configuration is disclosed in which, after being collected in the circulation tank 118, it is sent to the dust removal part circulation tank 103 and the spray nozzle 121 of the absorption tower absorption part A to be used for desulfurization of exhaust gas.

Further, Japanese Patent Application No. 2013-58724, which is a patent application filed on March 21, 2013 by the present applicant, proposes an exhaust gas treatment apparatus using seawater as shown in FIG. In the exhaust gas treatment apparatus shown in FIG. 7, a desulfurization liquid spray nozzle 109 for spraying seawater is installed at the upper portion of the desulfurization absorption tower 100, and a collector 122 for collecting the sprayed seawater is provided below the desulfurization spray nozzle 109. A dust removal spray nozzle 108 different from the desulfurization spray nozzle 109 is provided between the exhaust gas inlet duct 102 and the collector 122 located on the side, and dust removal and heavy metals in the exhaust gas are absorbed and removed by the dust removal spray nozzle 108. Seawater stored in the circulation tank 103 below the desulfurization absorption tower 100 is circulated and supplied to the dust removal spray nozzle 108 by a circulation pump 104. Further, the sprayed seawater that has come into contact with the exhaust gas from the collector 122 is sent into the oxidation tank 114 and is oxidized by the oxidation air sucked from the atmosphere through the intake pipe L5 by the microbubble generator 115, and the oxidation air blower 116. Is oxidized and treated by oxygen dissolved from bubbles blown from the air diffuser nozzle 117 and returned to the ocean 12 as seawater.

JP 2010-234334 A JP 2001-170444 A Japanese Patent Laid-Open No. 2008-200619 JP-A-61-259730

Further, the flue gas desulfurization device described in Patent Document 4 (Japanese Patent Laid-Open No. 61-259730) is a flue gas desulfurization device that uses an absorption liquid containing limestone as shown in FIG. 6 without using seawater. The absorption tower 100 is provided with a spray nozzle 121 for spraying the absorption liquid containing limestone to the exhaust gas, and the upper stage is divided into two upper and lower stages by the collector 122. A configuration is shown in which the lower part is a dust removing part B in which the absorption liquid from the circulation tank 103 circulates. The absorption liquid collected by the collector 122 is once stored in the circulation tank 118 of the absorption part A and then circulated and supplied to the absorption part A again.

The structure in which the empty tower portion of the absorption tower 100 is divided into upper and lower stages by the collector 122 does not completely separate the absorption tower absorption section A and the absorption tower dust removal section B by the collector 122 but is sprayed by the absorption section A. The absorbed liquid also flows down to the dust removing section B. A part of the circulation tank 103 below the dust removing section B is partitioned, and the liquid reservoir 109 collects gypsum having a large particle diameter as the liquid reservoir 109. It is.

That is, in the invention shown in FIG. 6, the absorption part A and the dust removal part B are not completely functionally separated, and the pump cavitation is exclusively prevented when the slurry is extracted from the circulation tank 103, and the air into the circulation tank 103 is prevented. The purpose is to smoothly oxidize the sulfite by blowing in, and the collector 122 does not completely separate the absorbing part A and the dust removing part B, and the exhaust gas treatment function in the absorbing part A and the dust removing part B is also separated. Not.

Further, in the inventions shown in Patent Document 1, FIG. 5, and FIG. 7, an absorption part provided with a spray nozzle for spraying the upper stage seawater on the absorption tower to the exhaust gas is provided, and the lower part is seawater or absorbent stored in the circulation tank. A dust removal part is circulated, and the collector is substantially partitioned by a collector.

However, in the inventions shown in Patent Document 1, FIG. 5 and FIG. 7, the exhaust gas absorbing liquid composed of seawater flowing down from the absorption section A is partially collected by the collector, but considerably flows into the lower dust removing section B from the collector gap. Therefore, it mixes only in the mixture of the absorption liquid and seawater containing the limestone circulating in the dust removal part B, or seawater. *

Moreover, since the dust and heavy metals in the exhaust gas are absorbed and removed only by the mixture of the absorbing liquid containing limestone and the seawater or the seawater that circulates from the storage section to the dust removal section B, the seawater in the storage section is discharged without purification. It is not possible. If a large amount of seawater flows down from the absorption section A into the seawater accumulated in such a storage section, it cannot be handled with a limited capacity of the absorption tower, so the seawater is discharged into the ocean without purification treatment.

Moreover, in the dust removal part B, since a part of seawater evaporates with the heat | fever from exhaust gas, it is necessary to always replenish seawater, but the amount of seawater which flows into the dust removal part B from the clearance gap between collectors is the amount of seawater supplied to the dust removal part B If it is several times larger than the water balance, the water balance cannot be achieved, and the storage space cannot be used.

In addition, when a part of the seawater sprayed in the dust removing section B for removing dust and heavy metals flows into the absorption section A as mist, the dust and heavy metals are released to the ocean through the collector.

Therefore, there is a need for a seawater flue gas desulfurization device that allows only the exhaust gas that is a gas to pass through the collector portion that partitions the absorption portion A and the dust removal portion B and that completely blocks the liquid.
The object of the present invention is to prevent the passage of liquid between a dust removing section for removing soot and heavy metals in exhaust gas and an absorbing section for removing sulfur oxide in exhaust gas in one absorption tower. It is to provide a flue gas desulfurization apparatus and its operation method.

The object of the present invention can be achieved by adopting the following constitution.
The invention according to claim 1 is provided with an inlet for introducing exhaust gas discharged from a combustion device including a boiler, and a circulation tank for storing seawater provided below the inlet, and repeatedly supplying seawater in the circulation tank. A dust removal spray nozzle that absorbs or contacts and removes dust and heavy metals in the exhaust gas introduced from the inlet, and sprays fresh seawater above the dust removal spray nozzle to remove sulfur oxide in the exhaust gas introduced from the inlet. An absorption tower provided with a desulfurization spray nozzle for absorbing and removing, an absorption tower provided with a collector for recovering seawater sprayed from the desulfurization spray nozzle between the dust removal spray nozzle and the desulfurization spray nozzle, and the sprayed seawater recovered by the collector is introduced to oxidize air Rectifier that rectifies sprayed seawater between collector and desulfurization spray nozzle in seawater flue gas desulfurization device equipped with oxidation tank for supplying A mist eliminator for mist removal is provided between the collector and the dust removal spray nozzle, and the absorption tower is provided with a rectifying member, a collector and a mist eliminator, and an absorption part A having a desulfurization spray nozzle and below the absorption part A. It is a seawater flue gas desulfurization apparatus characterized by being divided into a dust removal part B having a dust removal spray nozzle.

The invention according to claim 2 is characterized in that the rectifying member comprises a perforated plate, a plurality of fillers, or a slit plate in which a plurality of plates having a plane in the vertical direction are arranged in parallel. Device.

The invention according to claim 3 is a pump that uses potential energy when fresh seawater sprayed from a desulfurization spray nozzle recovered by a collector is supplied to an oxidation tank as a power source of seawater in a circulation tank sprayed from a dust removal spray nozzle. The seawater flue gas desulfurization apparatus according to claim 1, wherein:

According to a fourth aspect of the present invention, there is provided a seawater flue gas desulfurization apparatus according to the first aspect, wherein the lower collectors are arranged in a staggered manner below the gap between the upper collectors using at least two upper and lower collectors. is there.

The invention according to claim 5 is the supply amount of the seawater in the circulation tank sprayed from the dust removal spray nozzle in the seawater flue gas desulfurization apparatus according to claim 1 to the exhaust gas amount per unit time, and the fresh seawater sprayed from the desulfurization spray nozzle. The operation method of the seawater flue gas desulfurization apparatus is characterized in that the ratio of the supply amount to the exhaust gas amount per unit time is 1 to 4: 5 to 17.
(Function)
According to the present invention, fresh seawater is sprayed from the desulfurization spray nozzle to the exhaust gas discharged from the combustion device at the absorption part of the absorption tower to absorb and remove sulfur oxides in the exhaust gas. Seawater that has absorbed sulfur oxides in the exhaust gas is rectified by the rectifying member and collected by the collector. At this time, the seawater sprayed from the desulfurization spray nozzle flows down while being rectified by the flow straightening member downward in the vertical direction by the collector, so the flow area of the seawater is limited, and all the flowing seawater can be collected by the collector.

The fresh seawater sprayed from the desulfurization spray nozzle thus absorbs the sulfur oxides in the exhaust gas, and then all flows down into the oxidation tank provided outside the absorption tower through the collector. Does not flow down.

Moreover, the seawater sprayed by the absorption part can fully absorb and remove sulfur oxides in the exhaust gas by using a large amount of seawater sprayed by the dust removal part.
In this way, even if a large amount of seawater is sprayed in the absorption section, it can all flow down into the oxidation tank, and after being purified in the oxidation tank, the seawater can be discharged into the ocean. Since the seawater sprayed in is collected and does not flow down to the dust removal section, even if a large amount of seawater is sprayed in the absorption section, it does not impose a purification treatment load on the dust removal section.

On the other hand, by repeatedly spraying the seawater stored in the circulation tank from the dust removal spray nozzle in the dust removal unit, dust and heavy metals in the exhaust gas can be absorbed or removed in the sprayed seawater. Seawater repeatedly sprayed from this dust removal spray nozzle is much more contaminated with soot and dust than the seawater sprayed by the desulfurization spray nozzle of the absorber, so this contaminated seawater was purified in a wastewater treatment tank. Later it can be released into the ocean.

In addition, if seawater repeatedly sprayed from the dust removal spray nozzle rises to the absorption section, soot and heavy metals collected in the seawater will be released to the ocean via the collector, which may cause ocean pollution and should be avoided. There is. Therefore, the mist is removed by a mist eliminator provided above the dust removal spray nozzle and below the collector.

The invention according to claim 1 is characterized in that the seawater sprayed in the dust removing part and the absorbing part can be treated independently without being mixed by the rectifying member, the collector and the mist eliminator. Compared to the purification treatment technology of exhaust gas using seawater, the feature is that the seawater after purification treatment is clean, and even if a large amount of seawater is sprayed in the absorption section, purification processing of contaminated seawater in the dust removal section It is useful as a flue gas desulfurization device that uses inexpensive seawater without increasing the load.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the rectifying member comprises a slit plate in which a porous plate, a plurality of fillers, or a plurality of plates having a plane in the vertical direction are arranged in parallel. By using this, the sprayed seawater that spreads out from the absorption spray nozzle can flow downward in the vertical direction, and the rectified sprayed seawater can be reliably recovered by the collector.

According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 above, fresh sprayed from the desulfurization spray nozzle recovered by the collector as a power source for pumping up seawater in the circulation tank sprayed from the dust removal spray nozzle. By using a pump that uses potential energy when seawater is supplied to the oxidation tank, it is possible to reduce costs without using electric power as power used for the dust removal spray nozzle.

According to the invention described in claim 4, in addition to the effect of the invention described in claim 1, by using at least two upper and lower stages as collectors, the lower collectors are arranged in a staggered manner below the gap of the upper collector. The fresh seawater used in the absorption section will not flow down to the dust removal section, and the amount of seawater used in the dust removal section may be relatively small compared to the seawater used in the absorption section, and purification of contaminated seawater used in the dust removal section Processing becomes easy.

According to the fifth aspect of the present invention, the supply amount of the seawater in the circulation tank sprayed from the dust removal spray nozzle of the seawater flue gas desulfurization apparatus according to the first aspect to the exhaust gas amount per unit time and the freshness sprayed from the desulfurization spray nozzle The ratio of fresh seawater to the amount of exhaust gas supplied per unit time is 1 to 4: 5 to 17, which makes it possible to purify exhaust gas using seawater that does not increase the processing load of contaminated seawater. In addition, it is possible to easily set the amount of seawater sprayed in the absorbing portion in accordance with the SO ₂ concentration in the exhaust gas within the framework of laws and regulations concerning the desulfurization rate.

It is a figure which shows the system | strain of the seawater flue gas desulfurization apparatus which is one Example of this invention. It is an example of the rectification | straightening member arrange | positioned at the desulfurization absorption tower of FIG. It is a longitudinal cross-sectional view of the collector part arrange | positioned at the desulfurization absorption tower of FIG. It is a figure which shows the system | strain of the seawater flue gas desulfurization apparatus of a prior art. 1 is an overall configuration diagram of an exhaust gas treatment apparatus described in Japanese Patent Application No. 2012-279808 (patent application dated December 21, 2012). 1 is a configuration diagram of a flue gas desulfurization apparatus using an absorbing liquid containing limestone described in Japanese Patent Application Laid-Open No. 61-259730. 1 is a configuration diagram of an exhaust gas treatment apparatus described in Japanese Patent Application No. 2013-58724 (patent application dated March 21, 2013).

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, the system | strain of the seawater flue gas desulfurization apparatus which is one Example of this invention is shown. In the wet desulfurization apparatus in FIG. 1, the description of the members having the same reference numerals as those in the wet desulfurization apparatus in FIG. 4 is partially omitted.

The seawater wet desulfurization apparatus of this embodiment mainly discharges exhaust gas from a desulfurization absorption tower 1 for treating SOx in combustion exhaust gas from a boiler, an inlet duct 2 for introducing exhaust gas into the desulfurization absorption tower 1, and the desulfurization absorption tower 1. Outlet duct 3, desulfurization spray nozzle 9 for spraying seawater that absorbs SOx in exhaust gas onto exhaust gas, mist eliminator 7 for removing mist accompanying the exhaust gas flow, seawater pump 18 for supplying seawater to desulfurization spray nozzle 9, and SOx The point comprised from the oxidation tank 14 which oxidizes the sulfurous acid produced by absorption, the oxidation air blower 16 which sends the air supplied to the oxidation tank 14, the diffuser nozzle 17 which ejects the air sent by the oxidation air blower 16, etc. Thus, it is the same as the wet desulfurization apparatus of FIG.

The combustion exhaust gas is introduced from the inlet duct 2 into the desulfurization absorption tower 1 in a substantially horizontal direction, and is discharged from the outlet duct 3 provided at the top of the desulfurization absorption tower 1.
Seawater heated by a boiler condenser (not shown) is sent to the uppermost stream portion of the oxidation tank 14 through the dilution seawater pipe L3. In the desulfurization absorption tower 1, a part of the seawater is supplied to the seawater pump 18. The fresh water is fed from the seawater feed pipe L7 to the desulfurization spray nozzle 9 and the circulation tank 5 below the desulfurization absorption tower 1 through the absorption seawater feed pipe L2.

Fresh seawater sent to the desulfurization spray nozzle 9 is sprayed into the desulfurization absorption tower 1 as fine droplets, and the gas-liquid contact between the seawater and the exhaust gas is performed, so that SOx (mainly SO2) in the exhaust gas is changed. It is selectively absorbed and removed by the absorbing droplet surface of the desulfurization spray nozzle 9.

The seawater sprayed from the desulfurization spray nozzle 9 absorbs sulfur oxide in the exhaust gas, and the seawater that has absorbed the sulfur oxide is rectified by the rectifying member 22 and collected by the collector 10. The space between the desulfurization spray nozzle 9 and the collector 10 is referred to as an absorption part A in the desulfurization absorption tower 1.

In the seawater atomized by spraying from the desulfurization spray nozzle 9, the mist accompanying the flow of the exhaust gas is collected by a first mist eliminator 7 installed in the outlet duct 3 at the top of the desulfurization absorption tower 1. The The exhaust gas that has passed through the mist eliminator 7 is reheated as necessary, and then discharged into the atmosphere from a chimney (not shown).

Moreover, since the seawater sprayed from the desulfurization spray nozzle 9 in the absorption part A flows down while being rectified downward in the vertical direction by the rectifying member 22, the flow area of the seawater is limited. It is important to dispose the liquid receiving area of the collector 10 below the limited seawater flow-down area, and between the collectors 10 as viewed from above and between the collector 10 at both end portions and the wall surface of the absorption tower 1. Since no gap is formed between them, all the seawater flowing down from the rectifying member 22 can be collected by the collector 10.

Further, a collecting tank 11 (seawater collecting member) is provided at the most downstream portion of the collector 10 that collects the sprayed seawater, and the liquid level of the circulating tank 5 positioned below the collector 10 and the collecting tank 11 A dust removal spray nozzle 8 different from the desulfurization spray nozzle 9 is provided in the dust removal portion B which is a region between the collector 10. Seawater (absorbed liquid) stored in the circulation tank 5 below the desulfurization absorption tower 1 is circulated and supplied to the dust removal spray nozzle 8 by the absorption liquid circulation pump 4.

Further, the absorbing liquid (seawater) in the circulation tank 5 is agitated by the agitator 6. By spraying from the dust removing spray nozzle 8 while circulating the dust removing seawater (absorbing liquid consisting of), the dust and heavy metals in the exhaust gas are absorbed or removed by the absorbing liquid consisting of the dust removing seawater. A part of the absorption liquid consisting of seawater for dust removal in the circulation tank 5 is extracted from the absorption liquid extraction pipe L1 and purified by a method such as pH adjustment, addition of a chelating agent, coagulation sedimentation, etc. in the waste water treatment device 24. Is sent to the oxidation tank 14 through a water pipe L8.

A diffuser nozzle 17 is disposed in the oxidation tank 14, and sulfite is supplied by oxygen dissolved from the bubbles supplied from the oxidizer air blower 16 through the air supply pipe L 6 and ejected from the diffuser nozzle 17. Oxidized and processed and returned to the ocean 12 as seawater.

A second mist eliminator 23 is arranged between the dust removal spray nozzle 8 and the collector 10 so that a part of the seawater sprayed by the dust removal spray nozzle 8 does not reach the collector 10 and the absorption part A above the collector 10 as mist. ing.

As shown in FIG. 2, a porous plate (perspective view of FIG. 2 (a), cross-sectional view of FIG. 2 (b)), a configuration in which a plurality of fillers (Raschig rings) are stacked, or a plurality of vertical directions as the rectifying member 22 By using any one of the slit plates (FIG. 2 (d)) in which flat plates are arranged in parallel, the spray seawater spreading in a divergent form from the desulfurization spray nozzle 9 can be flowed downward in the vertical direction and rectified. Sprayed seawater can be reliably collected by the collector 10. When a perforated plate is used as the rectifying member 22, as shown in the cross-sectional view of FIG. 2B, a cylindrical portion having a protrusion in the vertical direction is formed below each hole. Only flows down.

As shown in a vertical cross-sectional view of the upwardly open bowl-shaped collector 10 in which the upper and lower stages are arranged in a staggered manner in FIG. 3, the lower stage is used as the collector 10 at least under the upper stage 10a using the upper and lower stages. By arranging the collectors 10b in a staggered manner, a gap is not formed in the projection view of the collector 10 viewed from above.

The seawater sprayed from the desulfurization spray nozzle 9 in the absorption section A of the absorption tower 1 is rectified by the rectifying member 22 and flows down while being rectified downward in the vertical direction toward the collector 10, so that the seawater flowing area is limited. For this reason, all the seawater flowing down in the absorption part A can be collected by the collector 10.

The fresh seawater sprayed from the desulfurization spray nozzle 9 thus absorbs the sulfur oxides in the exhaust gas, and then all flows down into the oxidation tank 14 provided outside the absorption tower via the collector 10. The seawater sprayed with the does not flow down.

Moreover, the seawater sprayed by the absorption part A can fully absorb and remove the sulfur oxide in the exhaust gas by using a large amount of seawater sprayed by the dust removal part B.
Thus, even if a large amount of seawater is sprayed in the absorption part A, all of it flows down into the oxidation tank 14 and is discharged into the ocean 12 after being oxidized in the oxidation tank 14 (this is sometimes referred to as one-through). ), The seawater sprayed in the absorbing part A by the rectifying member 22 and the collector 10 is collected and does not flow down to the dust removing part B.

On the other hand, in the dust removal section B, the seawater stored in the circulation tank 5 is repeatedly sprayed from the dust removal spray nozzle 8, so that dust and heavy metals in the exhaust gas can be absorbed or removed in the sprayed seawater. The seawater repeatedly sprayed from the dust removal spray nozzle 8 is considerably contaminated with dust and the like as compared with the seawater sprayed by the desulfurization spray nozzle 9 of the absorption section A. Therefore, the contaminated seawater is discharged in the waste water treatment tank 24. After the purification treatment, it is discharged to the ocean 12 through the water pipe L8 and the oxidation tank 14.

Moreover, if the mist in the seawater sprayed repeatedly from the dust removal spray nozzle 8 rises to the absorption part A, dust, heavy metals, etc. will be emitted into the mist via the collector 10 into the mist. Because it causes marine pollution, it is necessary to avoid this. Therefore, a second mist eliminator 23 is provided above the dust removal spray nozzle 8 and below the collector 10 to remove the mist.

Here, the seawater sprayed from the desulfurization spray nozzle 9 of the absorption section A can sufficiently absorb and remove sulfur oxides in the exhaust gas by using a large amount. Even if a large amount of seawater is sprayed from the desulfurization spray nozzle 9 of the absorption part A, all of the seawater flows down into the oxidation tank 14, and after being oxidized in the oxidation tank 14, the seawater is discharged into the ocean 12 and the rectifying member 22 and the collector 10. Thus, the seawater sprayed in the absorption part A is collected and does not flow down to the dust removal part B.

The sprayed seawater recovered from the collector 10 is sent into the oxidation tank 14, and the sulfite ion-containing seawater in the oxidation tank 14 is diluted with the dilution seawater sent from the dilution seawater pipe L3, and the oxidation air blower 16 Is oxidized by oxygen dissolved from the air (bubbles) sent from the air diffuser nozzle 17 and returned to the ocean 12 as treated seawater.

Further, a part of the seawater in the oxidation tank 14 is replenished to the circulation tank 5 from a water supply pipe L7 having an on-off valve 26 branched from the absorption seawater water supply pipe L2.
In this embodiment, the supply amount of the seawater in the circulation tank 5 sprayed from the dust removal spray nozzle 8 with respect to the exhaust gas amount per unit time and the supply amount of the fresh seawater sprayed from the desulfurization spray nozzle 9 with respect to the exhaust gas amount per unit time. The ratio is 1 to 4: 5 to 17. That is, the amount of fresh seawater sprayed from the desulfurization spray nozzle 9 with respect to the amount of exhaust gas per unit time is about 1.2 times or more than the amount of circulating seawater sprayed from the dust removal spray nozzle 8 with respect to the amount of exhaust gas per unit time. Thus, the sulfur oxide in the exhaust gas can be kept within the range of legal regulations. For this reason, there is an advantage that the amount of seawater spray can be easily set within the framework of the legal regulations concerning the SO ₂ concentration according to the SO ₂ concentration in the exhaust gas.

According to the present embodiment, the seawater sprayed by the dust removing part B and the absorbing part A can be treated independently without being mixed by the rectifying member 22, the collector 10 and the second mist eliminator 23. Moreover, compared with the conventional exhaust gas purification treatment technology using seawater, the seawater after the exhaust gas purification treatment is also relatively clean.

In this way, even if a large amount of seawater is used in the absorber A compared to the seawater used in the dust remover B, it is recovered by the collector 10 without flowing down to the dust remover B, and is used in the dust remover B, which is a relatively small amount. The load of the purification process in the seawater wastewater treatment tank 24 does not increase. Moreover, the more seawater sprayed by the absorption part A compared with the seawater sprayed by the dust removal part B, the more the sulfur oxide in the exhaust gas can be absorbed and removed.

In this way, even if a large amount of seawater is sprayed in the absorption part A, all of the seawater flows down into the oxidation tank 14 and can be discharged into the ocean 12 after being oxidized in the oxidation tank 14. And the seawater sprayed in the absorption part A by the collector 10 is collected and does not flow down to the dust removal part B.

Further, the potential energy generated when the seawater sprayed from the desulfurization spray nozzle 9 recovered by the collector 10 as the power source of the pump 4 for pumping up the seawater in the circulation tank 5 sprayed from the dust removal spray nozzle 8 is supplied to the oxidation tank 14. By using it through the water wheel 19, it is possible to reduce the cost without using electric power as power used for the dust removal spray nozzle 8. In addition, by using the water wheel 19 together with an electric motor (not shown), the electric motor is particularly useful when the water wheel 19 is started.

There is a possibility of using it as a flue gas desulfurization device that uses seawater that has not been discharged into the ocean while being contaminated.

DESCRIPTION OF SYMBOLS 1 Desulfurization absorption tower 2 Inlet duct 3 Outlet duct 4 Absorption liquid circulation pump 5 Circulation tank 6 Stirrer 7 1st mist eliminator 8 Dust removal spray nozzle 9 Desulfurization spray nozzle 10 Collector 11 Collection tank 12 Ocean 18 Seawater pump 14 Oxidation tank 15 Microbubble generation 16 Oxidizing air blower 17 Aeration nozzle 19 Water wheel 22 Rectification member
23 Second mist eliminator 24 Wastewater treatment tank 26 On-off valve
L1 Absorption liquid extraction pipe L2 Absorption seawater water supply pipe L3 Dilution seawater water supply pipe L4 Sulphite ion-containing seawater water supply pipe L5 Intake pipe L6 Air supply pipe L7 Seawater water supply pipe L8 Water supply pipe A Absorption part B Dust removal part

Claims

An inlet for introducing exhaust gas discharged from a combustion apparatus including a boiler and a circulation tank for storing seawater provided below the inlet are provided, and the exhaust gas introduced from the inlet by repeatedly supplying seawater in the circulation tank A dust removal spray nozzle that absorbs or contacts and removes dust and heavy metals therein is provided, and a desulfurization spray nozzle that absorbs and removes sulfur oxides in the exhaust gas introduced from the inlet by spraying fresh seawater above the dust removal spray nozzle, An absorption tower provided with a collector that collects seawater sprayed from the desulfurization spray nozzle between the dust removal spray nozzle and the desulfurization spray nozzle, and an oxidation tank that introduces the sprayed seawater recovered by the collector and supplies oxidized air are provided. In seawater flue gas desulfurization equipment,
A rectifying member that rectifies sprayed seawater is provided between the collector and the desulfurization spray nozzle,
A mist eliminator for removing mist is installed between the collector and the dust removal spray nozzle.
The inside of the absorption tower is divided into an absorption part A having a desulfurization spray nozzle and a dust removal part B having a dust removal spray nozzle provided below the absorption part A by a rectifying member, a collector and a mist eliminator. Desulfurization equipment.
2. The seawater flue gas desulfurization apparatus according to claim 1, wherein the rectifying member comprises a slit plate in which a porous plate, a plurality of fillers, or a plurality of plates having a plane in the vertical direction are arranged in parallel.
A pump that uses potential energy when fresh seawater sprayed from a desulfurization spray nozzle recovered by a collector is supplied to an oxidation tank is used as a power source of seawater in a circulation tank sprayed from a dust removal spray nozzle. Item 1. A seawater flue gas desulfurization apparatus according to item 1.
The seawater flue gas desulfurization apparatus according to claim 1, wherein the collector is arranged in a staggered manner below the gap between the upper collectors using at least two upper and lower stages.
The supply amount with respect to the exhaust gas amount per unit time of seawater in the circulation tank sprayed from the dust removal spray nozzle in the seawater flue gas desulfurization apparatus according to claim 1, and the supply with respect to the exhaust gas amount per unit time of fresh seawater sprayed from the desulfurization spray nozzle The operation method of the seawater flue gas desulfurization apparatus is characterized in that the ratio to the amount is 1 to 4: 5 to 17.