WO2021100628A1

WO2021100628A1 - Gypsum slurry dehydration system

Info

Publication number: WO2021100628A1
Application number: PCT/JP2020/042424
Authority: WO
Inventors: 覚杉田; 直行神山; 良三佐々木; 祐一郎里
Original assignee: 三菱パワー株式会社
Priority date: 2019-11-18
Filing date: 2020-11-13
Publication date: 2021-05-27
Also published as: TW202126370A; JP7351726B2; JP2021079319A

Abstract

A gypsum slurry dehydration system for dehydrating gypsum slurry discharged from a flue gas desulfurization apparatus comprises: a conveying device having a conveying belt for conveying the gypsum slurry on a filter cloth; a filter cloth cleaning device that has an ejection part capable of ejecting a filter cloth cleaning liquid onto the filter cloth; a filtrate storage tank configured to store a filtrate separated from the gypsum slurry by the filter cloth; a filtrate discharge line configured to send the filtrate stored in the filtrate storage tank to a wastewater treatment facility that performs treatment to discharge the filtrate to the outside of the system; and a filter cloth cleaning liquid storage tank that is different from the filtrate storage tank and is configured to store at least the filter cloth cleaning liquid ejected from the ejection part onto the filter cloth.

Description

Gypsum slurry dehydration system

The present disclosure relates to a gypsum slurry dehydration system for dehydrating gypsum slurry produced as a by-product in a flue gas desulfurization apparatus.

For example, since the exhaust gas emitted from a combustion engine such as a boiler contains air pollutants such as sulfur oxides (SOx), sulfur oxides are removed from the exhaust gas in the flue gas desulfurization apparatus before being released into the atmosphere. ..

As a flue gas desulfurization device, a wet flue gas desulfurization device using a lime gypsum method is widely known. In a wet flue gas desulfurization device, the exhaust gas is brought into contact with a limestone slurry (absorption liquid), and sulfur oxides (for example, sulfurous acid gas) in the exhaust gas are absorbed by the absorption liquid to remove sulfur oxides from the exhaust gas. It is being removed. The sulfur oxide absorbed in the absorption liquid reacts with calcium in the absorption liquid to become calcium sulfite, and the calcium sulfite is oxidized by the air supplied into the absorption liquid to become gypsum. In a wet flue gas desulfurization apparatus, gypsum slurry (absorption liquid containing gypsum) is produced as a by-product.

Patent Document 1 discloses that a slurry liquid containing a gypsum slurry extracted from a wet flue gas desulfurization apparatus is solid-liquid separated by a gypsum separator to recover gypsum. Further, in Patent Document 1, the filter cloth is movably supported on the belt stretched between the drums, and the gypsum slurry supplied on the filter cloth is sucked from below the belt to separate the filtrate and the gypsum. A belt-type plaster separator, a cleaning device for cleaning the filter cloth after discharging the plaster slurry with a cleaning liquid, and a liquid storage tank for storing the cleaning liquid after cleaning the filter cloth and the filtrate are disclosed. The liquid stored in the liquid storage tank is sent to the wastewater treatment facility, and after the wastewater is treated in a state where the wastewater treatment facility meets the discharge standard, the liquid is discharged to the outside of the system.

Japanese Unexamined Patent Publication No. 8-12389

As shown in Patent Document 1, the cleaning liquid and the filtrate after cleaning the filter cloth were collected in the same liquid storage tank and then sent to the wastewater treatment facility as wastewater. Since the wastewater treatment equipment needs to treat a large amount of wastewater sent from the liquid storage tank, there is a risk that the size of the wastewater treatment equipment will increase and the equipment cost will increase.

In view of the above circumstances, an object of at least one embodiment of the present disclosure is to reduce the amount of wastewater sent from the gypsum slurry dehydration treatment equipment to the wastewater treatment equipment, and to increase the size of the wastewater treatment equipment and the equipment cost. It is an object of the present invention to provide a gypsum slurry dehydration system capable of suppressing the increase in price.

The gypsum slurry dehydration system according to the present disclosure is
A gypsum slurry dehydration system for dehydrating gypsum slurry discharged from a flue gas desulfurization apparatus.
A transport device having a transport belt that transports the gypsum slurry in a state of being placed on a filter cloth, and
A filter cloth cleaning device having a ejection portion capable of ejecting the filter cloth cleaning liquid onto the filter cloth, and a filter cloth cleaning device.
A filtrate storage tank configured to store the filtrate separated from the gypsum slurry by the filter cloth, and
A filtrate discharge line configured to send the filtrate stored in the filtrate storage tank to a wastewater treatment facility that performs a treatment for discharging the filtrate to the outside of the system.
A filter cloth cleaning liquid storage tank different from the filtrate storage tank, which is configured to store at least the filter cloth cleaning liquid ejected from the ejection portion onto the filter cloth. Be prepared.

According to at least one embodiment of the present disclosure, the amount of wastewater sent from the gypsum slurry dehydration treatment equipment to the wastewater treatment equipment can be reduced, and the size of the wastewater treatment equipment and the increase in equipment cost can be suppressed. A gypsum slurry drainage system capable of draining is provided.

It is a schematic block diagram which shows schematic the whole structure of the exhaust gas cleaning system including the gypsum slurry dehydration system which concerns on one Embodiment of this disclosure. It is a schematic block diagram which shows schematic the whole structure of the gypsum slurry dehydration system which concerns on one Embodiment of this disclosure. It is explanatory drawing for demonstrating the wastewater treatment equipment in one Embodiment of this disclosure. It is explanatory drawing for demonstrating another example of the gypsum slurry dehydration system which concerns on one Embodiment of this disclosure.

Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, but are merely explanatory examples. Absent.
For example, expressions that represent relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" are exact. Not only does it represent such an arrangement, but it also represents a state of relative displacement with tolerances or angles and distances to the extent that the same function can be obtained.
For example, expressions such as "same", "equal", and "homogeneous" that indicate that things are in the same state not only represent exactly the same state, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state.
For example, the expression representing a shape such as a quadrangular shape or a cylindrical shape not only represents a shape such as a quadrangular shape or a cylindrical shape in a geometrically strict sense, but also an uneven portion or chamfering within a range where the same effect can be obtained. The shape including the part and the like shall also be represented.
On the other hand, the expression "includes", "includes", or "has" one component is not an exclusive expression that excludes the existence of another component.
The same reference numerals may be given to the same configurations, and the description thereof may be omitted.

(Exhaust gas cleaning system)
FIG. 1 is a schematic configuration diagram schematically showing an overall configuration of an exhaust gas cleaning system including a gypsum slurry dehydration system according to an embodiment of the present disclosure.
As shown in FIG. 1, the gypsum slurry dehydration system 1 according to some embodiments is mounted on the exhaust gas cleaning system 10. As shown in FIG. 1, the exhaust gas cleaning system 10 is discharged from a wet flue gas desulfurization device 20 for desulfurizing exhaust gas discharged from a combustion facility 11 such as an engine or a boiler, and a flue gas desulfurization device 20. The gypsum slurry desulfurization system 1 for dehydrating the gypsum slurry is provided.

The flue gas desulfurization apparatus 20 brings the exhaust gas discharged from the combustion equipment 11 into contact with the absorbing liquid to absorb sulfur oxides (for example, sulfurous acid gas) in the exhaust gas into the absorbing liquid, thereby oxidizing sulfur from the exhaust gas. It is configured to remove objects. In the flue gas desulfurization apparatus 20 using the limestone method, for example, a slurry liquid containing an alkaline component such as a limestone slurry in which limestone is dissolved (dispersed) is used as the absorption liquid, and a gypsum slurry (absorption liquid containing gypsum) is a by-product. Will be done. Although the slurry is not strictly a liquid, it is treated as a liquid in the present specification for convenience.

The flue gas desulfurization apparatus 20 includes an absorption tower 20A configured to desulfurize the exhaust gas introduced into the flue gas desulfurization apparatus 20. The absorption tower 20A includes an absorption tower main body 22 configured to internally define an internal space 21 into which the exhaust gas discharged from the combustion equipment 11 is introduced, and an exhaust gas introduction port 23 for introducing the exhaust gas into the internal space 21. And an exhaust gas discharge port 24 for discharging exhaust gas from the internal space 21. Each of the exhaust gas introduction port 23 and the exhaust gas discharge port 24 communicates with the absorption tower main body 22.

The internal space 21 is located below the gas-liquid contact portion 21A for bringing the exhaust gas and the absorbed liquid into gas-liquid contact, and is located below the gas-liquid contact portion 21A, and the sulfur oxide (for example, sulfur oxide in the exhaust gas) in the gas-liquid contact portion 21A. , A liquid pool portion 21B in which an absorption liquid that has absorbed (sulfurous acid gas) is stored.

The exhaust gas discharged from the combustion equipment 11 is introduced into the internal space 21 through the exhaust gas introduction port 23. The exhaust gas guided to the internal space 21 flows while rising in the internal space 21 and is washed by the absorbing liquid when passing through the gas-liquid contact portion 21A, and sulfur oxides and the like in the exhaust gas are removed. The exhaust gas after cleaning in the gas-liquid contact portion 21A is discharged to the outside of the absorption tower 20A through the exhaust gas discharge port 24 as purified gas which is the purified exhaust gas. The purified gas discharged to the outside of the absorption tower 20A is discharged into the atmosphere from a chimney (not shown) provided on the downstream side of the exhaust gas discharge port 24 in the flow direction of the purified gas (exhaust gas). As shown in FIG. 1, even if the mist eliminator 25 configured to remove water from the purified gas (exhaust gas) is provided downstream of the gas-liquid contact portion 21A in the flow direction of the purified gas (exhaust gas). Good.

In the illustrated embodiment, the absorption tower 20A further includes a spraying device 26 arranged at the gas-liquid contact portion 21A. The spraying device 26 is configured to spray an absorbing liquid (limestone slurry) on the exhaust gas passing through the gas-liquid contact portion 21A. The absorbing liquid sprayed from the spraying device 26 comes into contact with the exhaust gas and absorbs and removes sulfur oxides (for example, sulfurous acid gas) contained in the exhaust gas.

The spraying device 26 includes a spray pipe 261 extending along a horizontal direction that intersects the flow direction of exhaust gas, and a plurality of spray nozzles 262 provided in the spray pipe 261. As shown in FIG. 1, the spray nozzle 262 has a spray port 263 that sprays the absorption liquid toward the downstream side in the flow direction of the exhaust gas, that is, toward the upper side in the vertical direction. In some other embodiments, the spray nozzle 262 may have a spray port for spraying the absorbing liquid downward in the vertical direction.

In the liquid pool portion 21B, the exhaust gas guided to the internal space 21 is sprayed from the spray port 263 of the spray nozzle 262, and the absorbing liquid that has absorbed and removed the sulfur oxide contained in the exhaust gas falls and is stored. .. The absorbing liquid stored in the pool portion 21B may contain sulfites produced by sulfur oxides absorbed from exhaust gas and gypsum (calcium sulfate) produced by oxidation of sulfites.

The absorption tower main body 22 has an absorption liquid outlet 221 for extracting the absorption liquid stored in the liquid pool 21B to the outside, and an oxidizing gas (for example, air) in the absorption liquid stored in the liquid pool 21B. The nozzle penetration port 222 through which the nozzle for supplying is penetrated is open. Each of the absorption liquid outlet 221 and the nozzle through port 222 communicates with the liquid pool portion 21B. Further, the absorption tower main body 22 is opened with an absorption liquid supply port 223 for introducing the limestone slurry and an absorption liquid return port 224 for returning the absorption liquid extracted to the outside to the liquid pool portion 21B. Each of the absorption liquid supply port 223 and the absorption liquid return port 224 communicates with the internal space 21 above the liquid pool portion 21B.

The absorption tower 20A further includes an oxidation gas supply device 27 configured to supply an oxidation gas (for example, air) to the absorption liquid stored in the liquid pool 21B. In the illustrated embodiment, the oxidizing gas supply device 27 includes a nozzle 271 penetrating the nozzle through port 222 and a pump 272 that supplies atmospheric air to the nozzle 271. The air in the atmosphere (oxidation air) is supplied to the nozzle 271 by the pump 272, and is supplied to the absorption liquid stored in the liquid pool 21B from the opening 273 at the tip of the nozzle. As a result, the sulfite in the absorbing liquid stored in the pool portion 21B can be oxidized to form gypsum.

The absorption tower 20A sends the absorption liquid supply line 12 configured to supply the absorption liquid to the liquid pool portion 21B of the absorption tower 20A and the absorption liquid extracted from the liquid pool portion 21B to the spray device 26. Further includes a configured absorption liquid circulation line 13 and an absorption liquid extraction line 14 configured to send the absorption liquid extracted from the liquid pool portion 21B to the gypsum slurry dehydration system 1. The absorption tower 20A circulates the absorption liquid through the spray device 26, the liquid pool portion 21B, and the absorption liquid circulation line 13. Since the absorbing liquid stored in the liquid pool portion 21B is repeatedly used for cleaning the exhaust gas in the absorbing tower 20A, gypsum is gradually accumulated. By sending the gypsum slurry (absorption liquid containing gypsum) to the gypsum slurry dehydration system 1 via the absorption liquid extraction line 14, the absorption liquid circulation system (spraying device 26, liquid pool 21B, absorption liquid circulation line 13). The plaster is extracted from. In addition, in order to achieve both absorption and removal of sulfur oxides in the exhaust gas by the absorption liquid (higher pH is better efficiency) and oxidation of sulfites in the absorption liquid (lower pH is better efficiency). The absorption liquid is appropriately supplied through the absorption liquid supply line 12 so that the pH of the absorption liquid is in the range of 5 to 6.

In the illustrated embodiment, the absorbent liquid supply line 12 is arranged outside the absorption tower 20A and one end of the absorbent liquid storage tank 17 configured to define an internal space 171 for storing the absorbent liquid. The absorption liquid supply pipe 121 whose side is connected and the other end side is connected to the absorption liquid supply port 223 and the absorption liquid supply pipe 121 are provided, and the absorption liquid is sent from one end side to the other end side of the absorption liquid supply pipe 121. Includes a supply pump 122, configured as described above. By driving the supply pump 122, the absorption liquid is extracted from the internal space 171 and supplied to the liquid pool portion 21B of the absorption tower 20A.

In the illustrated embodiment, the absorption liquid circulation line 13 is provided in the absorption liquid circulation pipe 131 in which one end side is connected to the absorption liquid outlet 221 and the other end side is connected to the spray pipe 261 and the absorption liquid circulation pipe 131. In addition, the circulation pump 132 configured to send the absorption liquid from one end side to the other end side of the absorption liquid circulation pipe 131 is included. One end of the absorption liquid extraction line 14 is connected to the first branch portion 133 located on the downstream side (spraying device 26 side) in the flow direction of the absorption liquid from the circulation pump 132 of the absorption liquid circulation pipe 131, and the other end side is plaster. The absorption liquid extraction pipe 141 connected to the slurry dehydration system 1 (specifically, the supply device 4 shown in FIG. 2) is included. In this case, the absorption liquid circulation line 13 and the absorption liquid extraction line 14 share the circulation pump 132. By driving the circulation pump 132, the absorbing liquid is extracted from the pool portion 21B and supplied to the spray device 26 and the gypsum slurry dehydration system 1. In some other embodiments, the absorption liquid extraction line 14 may not have a shared portion with the absorption liquid circulation line 13.

In the illustrated embodiment, the absorption liquid extraction line 14 further includes a regulating valve 142 provided on the other end side of the absorption liquid extraction pipe 141. The regulating valve 142 has a movable mechanism for opening and closing the absorption liquid extraction pipe 141, which is a flow path of the absorption liquid, and allows the flow rate of the absorption liquid flowing through the absorption liquid extraction pipe 141 and being supplied to the gypsum slurry dehydration system 1. It is configured to be adjustable.

The absorption tower 20A further includes an absorption liquid return line 15 for returning the absorption liquid from the absorption liquid extraction line 14 to the liquid pool portion 21B of the absorption tower 20A. One end of the absorption liquid return line 15 is connected to the second branch portion 143 located on the upstream side (first branch portion 133 side) in the flow direction of the absorption liquid from the adjusting valve 142 of the absorption liquid extraction pipe 141, and the other end. Includes an absorbent liquid return pipe 151 whose side is connected to the absorbent liquid return port 224. At least a part of the absorption liquid flowing through the absorption liquid extraction pipe 141 is pumped by the circulation pump 132 and returned to the absorption tower 20A via the absorption liquid return pipe 151. Even when the amount of the absorption liquid supplied to the gypsum slurry dehydration system 1 is small, a larger amount of the absorption liquid than the required amount to be supplied to the gypsum slurry dehydration system 1 is flowed through the absorption liquid extraction pipe 141 to absorb the excess liquid. By returning the liquid to the absorption tower 20A via the absorption liquid return pipe 151, the flow velocity of the absorption liquid (plaster slurry) in the absorption liquid extraction pipe 141 is maintained at a predetermined speed or higher, and the solid content in the absorption liquid (for example). , Slurry, etc.) can be prevented from settling in the absorption liquid extraction pipe 141.

(Gypsum slurry dehydration system)
FIG. 2 is a schematic configuration diagram schematically showing the overall configuration of the gypsum slurry dehydration system according to the embodiment of the present disclosure.
The gypsum slurry dehydration system 1 according to some embodiments is configured to dehydrate the gypsum slurry (absorption liquid containing gypsum) sent from the absorption tower 20A via the absorption liquid extraction pipe 141 and separate it into gypsum and a filtrate. Has been done.

As shown in FIG. 2, the gypsum slurry dehydration system 1 has a transport device 3 having a transport belt 32 for transporting the gypsum slurry on the filter cloth 31, and a gypsum slurry on the filter cloth 31 of the transport belt 32. In order to clean the gypsum cake formed on the filter cloth 31 in the process of transporting the gypsum slurry while being dehydrated, the gypsum cleaning liquid can be ejected toward the gypsum cake. It is provided with a cake cleaning device 44 having a gypsum cleaning liquid ejection portion 45, and a steam ejection device 54 having a steam ejection portion 55 (spouting portion) capable of ejecting drying steam. Each of the supply unit 41, the cake cleaning liquid ejection unit 45, and the steam ejection unit 55 is arranged above the transport belt 32. The cake cleaning liquid ejection part 45 is located on the downstream side (right side in FIG. 2) in the direction along the conveying direction of the transport belt 32 from the supply portion 41, and the steam ejection portion 55 is the transport belt 32 rather than the cake cleaning liquid ejection portion 45. It is located on the downstream side in the direction along the transport direction of.

In the illustrated embodiment, the transport device 3 is connected to two rotatably supported drums 33 (33A, 33B) and one of the above two drums 33 (eg, 33A). It further includes a motor 34 configured to rotationally drive the drum 33 (33A), and a plurality of guide rollers 35. The transport belt 32 is made of an endless band-shaped rubber member (elastic body), and is rotatably hung on two drums 33 arranged apart from each other in the horizontal direction. Since the transport belt 32 is stretched on the two drums 33, the motor 34 rotationally drives one of the drums 33 (33A) to rotate the other drum 33 (33B) and the transport belt. 32 orbits along the transport direction of the transport belt 32.

The filter cloth 31 is provided in an endless band shape, is rotatably hung on a plurality of guide rollers 35, and a part of the filter cloth 31 in the length direction is overlapped on the upper surface 321 of the transport belt 32. The portion of the filter cloth overlapped on the upper surface 321 of the transport belt 32 (hereinafter referred to as the supported portion 311) is supported by the transport belt 32 together with the transport belt 32 so as to travel along the transport direction. Therefore, when the drum 33 (33A) is rotationally driven and the transport belt 32 orbits around, the supported portion 311 of the filter cloth 31 together with the support portion 322 that supports the supported portion 311 of the transport belt 32 from below. It travels along the above-mentioned transport direction. In certain embodiments, the filter cloth 31 comprises a woven fabric formed by weaving a fibrous formed resin material (eg, polyester, polypropylene, etc.). Also, in some other embodiments, the filter cloth 31 includes a non-woven fabric formed by entwining fibrous resin materials (eg, polyester, polypropylene, etc.).

The supply device 4 is configured to supply the gypsum slurry sent from the absorption tower 20A via the absorption liquid extraction line 14 from the supply unit 41 onto the filter cloth 31 of the transport belt 32. In the illustrated embodiment, the supply device 4 is connected to the supply unit 41 (for example, an injection nozzle) and one end side thereof to the other end side of the absorption liquid extraction pipe 141, and the other end side is connected to the supply unit 41. It has a supply pipe 42 and. In this case, the gypsum slurry is pumped by the circulation pump 132 described above, passes through the supply pipe 42, flows down from the supply unit 41, and is supplied onto the filter cloth 31 of the transport belt 32. Strictly speaking, "on the filter cloth 31 of the transport belt 32" means on the upper surface (outer surface) 312 of the supported portion 311 of the filter cloth 31.

The gypsum slurry is placed on the filter cloth 31 of the transport belt 32 and dehydrated when it is transported together with the filter cloth 31 by the transport belt 32. The region where the gypsum slurry is dehydrated in the transport device 3 is designated as the dehydration section 36. In the dehydration section 36, the transport belt 32 is located above the drum 33, and the supported portion 311 of the filter cloth 31 is supported by the support portion 322 of the transport belt 32. Each of the supply unit 41, the cake cleaning liquid ejection unit 45, and the steam ejection unit 55 described above is arranged in the region of the dehydration unit 36.

The filter cloth 31 is breathable, and the transport belt 32 is formed with a plurality of holes for allowing the filtrate to pass through. The gypsum slurry placed on the filter cloth 31 of the transport belt 32 is dehydrated by the filtrate passing through the filter cloth 31 and the transport belt 32 in the dehydration section 36.

In the illustrated embodiment, the transport device 3 further includes a dehydrator device 37 configured to dehydrate the filtrate by sucking the gypsum slurry placed on the filter cloth 31 from below. The dehydration device 37 is provided below the support portion 322 of the transport belt 32, and has a dehydration chamber 371 in which the internal pressure is held at a negative pressure (pressure lower than the atmospheric pressure), a vacuum pump 372, and a dehydration chamber 371. Includes a decompression pipe 373 having one end connected to the vacuum pump 372 and the other end connected to the vacuum pump 372, and a vacuum tank 374 provided in the decompression pipe 373. By driving the vacuum pump 372, the dehydration chamber 371 is depressurized to a negative pressure, the water in the gypsum slurry placed on the filter cloth 31 is forcibly sucked from below, and the gypsum slurry is dehydrated.

The water (filter liquid) sucked by the vacuum pump 372 and sent from the dehydration chamber 371 to the vacuum tank 374 is a liquid discharge pipe whose one end is connected to the lower end of the vacuum tank 374 and the other end extends downward. It passes through 375 and flows down into a filtrate storage tank 6 configured to store the filtrate.

The gypsum slurry that is placed on the filter cloth 31 and transported is dehydrated as it is transported to the transport belt 32 and becomes a cake. In the illustrated embodiment, the cake cleaning device 44 has one end connected to the cake cleaning liquid ejection portion 45 (for example, an injection nozzle) and the cake cleaning liquid ejection portion 45, and the other end connected to a cleaning liquid tank (not shown). It has a cake cleaning liquid supply pipe 46 to be formed, and a pump 47 provided in the cake cleaning liquid supply pipe 46. By driving the pump 47, the cleaning liquid is sent from the cleaning liquid tank to the cake cleaning liquid ejection portion 45, and is ejected from the cake cleaning liquid ejection portion 45 toward the gypsum slurry (cake) on the filter cloth located below. The gypsum slurry (cake) is washed with a washing liquid to remove impurities (for example, metal ions such as magnesium (Mg), chlorine (Cl), and sodium (Na)). Examples of the cake cleaning liquid include industrial water. The cake cleaning liquid used for washing the cake is sucked by the dehydrating device 37, passes through the filter cloth 31 and the transport belt 32, is sent as the filtrate from the dehydration chamber 371 to the vacuum tank 374, and flows through the liquid discharge pipe 375. It flows down to the filtrate storage tank 6.

In the illustrated embodiment, drying steam is sent to the steam ejection portion 55 (for example, an injection nozzle) of the steam ejection device 54 from a steam pipe 56 connected to a boiler (not shown), and is located below the steam ejection portion 55. It is ejected toward the gypsum slurry on the filter cloth 31. In the gypsum slurry on the filter cloth 31, the water contained in the gypsum slurry is removed by heating with the steam for drying.

In the illustrated embodiment, the gypsum obtained by dehydrating the gypsum slurry on the filter cloth 31 in the dehydration section 36 is located downstream of the dehydration section 36 (for example, the steam ejection section 55) in the transport direction of the transport belt 32. , Removed from the top of the filter cloth 31. The region where the gypsum is removed from the filter cloth 31 in the transport device 3 is referred to as the gypsum discharge portion 43.

As shown in FIG. 2, the gypsum slurry dehydration system 1 provides a filter cloth cleaning liquid ejection portion 51 capable of ejecting the filter cloth cleaning liquid to the filter cloth 31 on the downstream side of the gypsum discharge portion 43 in the transport direction of the transport belt 32. The filter cloth cleaning device 5 to be provided is further provided. In the illustrated embodiment, the filter cloth cleaning device 5 has a filter cloth cleaning liquid ejection portion 51 (for example, an injection nozzle) arranged below the two drums 33, and one end portion of the filter cloth cleaning liquid ejection portion 51. It has a filter cloth cleaning liquid supply pipe 52 which is connected and whose other end is connected to a cleaning liquid tank (not shown), and a pump 53 provided in the filter cloth cleaning liquid supply pipe 52. By driving the pump 53, the cleaning liquid is sent from the cleaning liquid tank to the filter cloth cleaning liquid ejection portion 51, and is ejected from the filter cloth cleaning liquid ejection portion 51 toward the filter cloth 31. Impurities are removed from the filter cloth 31 by cleaning it with a cleaning solution. Examples of the filter cloth cleaning liquid include industrial water. The filter cloth cleaning liquid is ejected toward at least one of the outer surface and the inner surface of the filter cloth 31.

As shown in FIG. 2, for example, the gypsum slurry dehydration system 1 is connected to a filter cloth cleaning liquid receiving portion 58 (for example, a tray) provided below the filter cloth cleaning liquid ejecting portion 51 and one end side to the filter cloth cleaning liquid receiving portion 58. Further, a filter cloth cleaning liquid discharge pipe 59 having the other end extending downward is further provided. The filter cloth cleaning liquid ejected from the filter cloth cleaning liquid ejection portion 51 falls onto the filter cloth cleaning liquid receiving portion 58. The filter cloth cleaning liquid that has fallen onto the filter cloth cleaning liquid receiving portion 58 passes through the filter cloth cleaning liquid discharge pipe 59 and flows down into the filter cloth cleaning liquid storage tank 8 configured to store the filter cloth cleaning liquid.

In the illustrated embodiment, the gypsum slurry dehydration system 1 is arranged outside the absorption tower 20A, and the filtrate storage tank 6 is configured to define an internal space 61 for storing the filtrate. , The filtrate stored in the filter cloth cleaning liquid storage tank 8 and the filtrate storage tank 6 arranged outside the absorption tower 20A and configured to define the internal space 81 for storing the filter cloth cleaning liquid. The liquid stored in the filtrate discharge line 7 and the filter cloth cleaning liquid storage tank 8 configured to send the filtrate to the wastewater treatment facility 16 that performs the treatment for discharging the filtrate to the outside of the system. A water supply line 9 configured to send to the storage tank 17 is further provided. That is, the liquid (filter liquid) stored in the filtrate storage tank 6 is discharged to the outside of the system after being sent to the wastewater treatment facility 16, and contains the liquid (including the filter cloth cleaning liquid) stored in the filter cloth cleaning liquid storage tank 8. The liquid) is sent to the absorption liquid storage tank 17, mixed with the limestone supplied through a supply line (not shown), and sent to the absorption tower 20A as an absorption liquid.

As shown in FIG. 2, the gypsum slurry dehydration system 1 according to some embodiments includes the above-mentioned transport device 3 having a transport belt 32 for transporting the gypsum slurry in a state of being placed on the filter cloth 31 and the filter cloth. The above-mentioned filter cloth cleaning device 5 having a filter cloth cleaning liquid ejection portion 51 (spouting portion) capable of ejecting the filter cloth cleaning liquid with respect to 31 and the above-mentioned above-mentioned configured to store the filtrate separated from the gypsum slurry by the filter cloth 31. The filtrate storage tank 6 and the above-mentioned filtrate discharge line 7 configured to send the filtrate stored in the filtrate storage tank 6 to a wastewater treatment facility 16 that performs a treatment for discharging the filtrate to the outside of the system. The filter cloth cleaning liquid storage tank 8 is different from the liquid storage tank 6, and is configured to store at least the filter cloth cleaning liquid ejected from the filter cloth cleaning liquid ejection portion 51 (spouting portion) to the filter cloth 31. A filter cloth cleaning liquid storage tank 8 is provided.

The gypsum slurry discharged from the flue gas desulfurization apparatus 20 absorbs impurities (for example, suspended solids such as combustion ash and soot removed from the exhaust gas and pollutants such as molten heavy metals) from the exhaust gas in the flue gas desulfurization apparatus 20. doing. Then, in a dehydration treatment facility (for example, a transport device 3 or the like), impurities are separated from the gypsum together with the filtrate from the gypsum slurry. Further, the cake washing liquid used for washing the cake contains impurities such as metal ions such as magnesium (Mg), chlorine (Cl) and sodium (Na). Therefore, the cake cleaning solution sent to the filtrate storage tank as the filtrate after being used for cleaning the filtrate or cake separated from the gypsum slurry is compared with the filter cloth cleaning solution ejected to the filter cloth 31. , High impurity content. Returning the filtrate having a high impurity content to the circulation system of the absorption liquid in the flue gas desulfurization apparatus 20 is not appropriate because the content of impurities in the absorption liquid in the flue gas desulfurization apparatus 20 increases. It is preferable that the filtrate having a high impurity content is discharged to the outside of the system after the wastewater treatment in the wastewater treatment facility 16.

According to the above configuration, the filtrate separated from the gypsum slurry and the cake cleaning solution used for washing the cake can be stored in the filtrate storage tank 6, and the filter cloth cleaning solution ejected to the filter cloth 31 can be filtered. It can be stored in the cloth cleaning liquid storage tank 8. Then, the filtrate stored in the filtrate storage tank 6 can be sent to the wastewater treatment facility 16 via the filtrate discharge line 7, and can be discharged to the outside of the system after the wastewater treatment in the wastewater treatment facility 16. In this way, the filtrate having a high impurity content and the filter cloth cleaning solution having a low impurity content are separately stored, and the wastewater sent to the wastewater treatment facility 16 is the impurities stored in the filtrate storage tank 6. By limiting to the filtrate having a high content rate, the amount of wastewater sent from the dewatering treatment equipment for the gypsum slurry to the wastewater treatment equipment 16 can be reduced by the amount of the filter cloth cleaning liquid. Further, by reducing the amount of wastewater sent to the wastewater treatment facility 16, it is possible to suppress an increase in the size of the wastewater treatment facility 16 and an increase in equipment cost.

In some embodiments, in the filtrate storage tank 6 described above, as shown in FIG. 2, among the filtrates stored in the filtrate storage tank 6, the filtrates having a height H1 exceeding a predetermined height are filtered. It is configured to overflow into the cleaning liquid storage tank 8.

In the illustrated embodiment, as shown in FIG. 2, the filtrate storage tank 6 has a square tubular inner side surface 62 and a bottom surface 63. The internal space 61 is partitioned by an inner side surface 62 and a bottom surface 63. The filter cloth cleaning liquid storage tank 8 has a square tubular inner side surface 82 and a bottom surface 83. The internal space 81 is partitioned by an inner side surface 82 and a bottom surface 83. In the embodiment shown in FIG. 2, the bottom surface 83 of the filter cloth cleaning liquid storage tank 8 is configured to be at the same height as the bottom surface 63 of the filtrate storage tank 6. The filtrate storage tank 6 is arranged adjacent to the filter cloth cleaning liquid storage tank 8 with a weir 64 sandwiched between the filtrate cleaning liquid storage tank 8 and the filter cloth cleaning liquid storage tank 8. The weir 64 is erected upward from the bottom surface 63 in the vertical direction, has one side 62A of the inner side surface 62 on one side, and has one side 82A of the inner side surface 82 on the other side. Have in. In this case, among the filtrates stored in the filtrate storage tank 6, the filtrate that exceeds the height of the upper end of the weir 64, which is the predetermined height H1, exceeds the weir 64 and the filter cloth cleaning liquid storage tank 8 Flow into. In some other embodiments, instead of the weir 64, one end is connected to the predetermined height position of the filtrate storage tank 6, and the other end is the predetermined height of the filter cloth cleaning liquid storage tank 8. An overflow pipe connected to a position lower than the vertical position may be provided.

According to the above configuration, in the filtrate storage tank 6, among the filtrates stored in the filtrate storage tank 6, the filtrate that exceeds a predetermined height H1 overflows into the filter cloth cleaning liquid storage tank 8. It is configured. Therefore, a filtrate other than the predetermined amount of filtrate that needs to be sent to the wastewater treatment facility 16 can be sent to the filter cloth cleaning liquid storage tank 8 without going through complicated equipment such as a pump or level control. It is possible to suppress the complexity and cost of equipment.
Further, for example, even when a filtrate exceeding the amount that can be treated by the wastewater treatment facility 16 is supplied to the filtrate storage tank 6, only the amount that can be treated from the filtrate storage tank 6 to the wastewater treatment facility 16 When the filtrate is sent, the remaining filtrate that exceeds the treatable amount naturally overflows into the filter cloth cleaning liquid storage tank 8 and is stored in the filter cloth cleaning liquid storage tank 8, so that the wastewater is treated. It is not necessary to make the equipment 16 a large equipment with a margin, and it is possible to suppress the increase in the cost of the wastewater treatment equipment 16.

In some embodiments, the above-mentioned filtrate discharge line 7 includes a drainage pipe 71 connected to the above-mentioned filtrate storage tank 6 and the above-mentioned wastewater treatment facility 16, and a drainage pump 72 provided in the drainage pipe 71. A flow control valve 73 provided on the downstream side of the drainage pump 72 in the drainage pipe 71 and configured to be able to adjust the flow rate of the filtrate sent from the filtrate storage tank 6 to the wastewater treatment facility 16 is included at least.

FIG. 3 is an explanatory diagram for explaining the wastewater treatment equipment according to the embodiment of the present disclosure.
As shown in FIG. 3, the wastewater treatment facility 16 has an internal space 162 configured to store wastewater, and has a first coagulation sedimentation tank 161 in which coagulation sedimentation treatment is performed and wastewater. It has at least a second coagulation sedimentation tank 163 having a configured internal space 164 and performing a coagulation sedimentation treatment. The second coagulation sedimentation tank 163 is provided on the downstream side in the drainage flow direction with respect to the first coagulation sedimentation tank 161.

The wastewater treatment facility 16 is configured to add a coagulant to the first coagulant addition line 165 configured to add the coagulant to the first coagulation settling tank 161 and to add the coagulant to the second coagulation settling tank 163. 2 Further includes a flocculant addition line 166. By adding a coagulant (for example, an aluminum compound such as aluminum sulfate) to the first coagulation sedimentation tank 161 by the first coagulant addition line 165, aluminum hydroxide flocs are precipitated in the wastewater and removed from the exhaust gas. Suspended solids such as burnt ash and soot and impurities such as pollutants such as molten heavy metals are included in the flocs and precipitated. By adding a coagulant (for example, sodium carbonate) to the second coagulation sedimentation tank 163 by the second coagulant addition line 166, calcium carbonate flocs are precipitated in the wastewater, and suspended solids and the like are transferred to the flocs. Contained and settled. A pH adjuster may also be added to the first coagulation sedimentation tank 161 and the second coagulation sedimentation tank 163.

The first coagulation sedimentation tank 161 is connected to the downstream side of the flow rate adjusting valve 73 of the drainage pipe 71, and drainage (filter liquid) is sent from the filtrate storage tank 6 via the drainage pipe 71. The first coagulation sedimentation tank 161 is the wastewater that has been condensed in the first coagulation sedimentation tank 161 among the wastewater stored in the first coagulation sedimentation tank 161. It is configured to overflow into the second coagulation sedimentation tank 163.

In the illustrated embodiment, the first coagulation sedimentation tank 161 has a weir 167 provided between the second coagulation sedimentation tank 163 arranged adjacent to the first coagulation sedimentation tank 161 and drainage from the weir 167. Further includes a partition 168 provided on the upstream side in the flow direction. The partition 168 hangs below the upper end of the weir 167, so that the first coagulation sedimentation tank 161 is located on one side where drainage is discharged from the drainage pipe 71 and on the side opposite to the one side with the partition 168 in between. It is divided into the other side and the other side. On the other side of the first coagulation sedimentation tank 161, wastewater that has been subjected to the coagulation sedimentation treatment in the first coagulation sedimentation tank 161 is mainly stored. In this case, of the liquid stored on the other side of the first coagulation sedimentation tank 161, the drainage exceeding the height of the upper end of the weir 167, which is the predetermined height H2, exceeds the weir 167 and is the second. 2 Flows into the coagulation sedimentation tank 163. The wastewater treatment equipment 16 includes an impurity removing mechanism (not shown) configured to remove the settled flocs in the first coagulation sedimentation tank 161 and the second coagulation sedimentation tank 163. Further, in some other embodiments, an overflow pipe may be provided instead of the weir 167 described above.

In the wastewater treatment facility 16, if the amount of wastewater sent to each tank such as the first coagulation sedimentation tank 161 and the second coagulation sedimentation tank 163 is large, the wastewater is sent to the downstream side before the impurities are sufficiently removed in each tank. Therefore, there is a risk that the wastewater treatment will be insufficient. Therefore, it is preferable that the above-mentioned filtrate discharge line 7 sends an amount of filtrate corresponding to the treatment performance of the wastewater treatment equipment 16 to the wastewater treatment equipment 16.

According to the above configuration, the filtrate discharge line 7 includes a drainage pipe 71 connected to the filtrate storage tank 6 and the wastewater treatment facility 16, a drainage pump 72 provided in the drainage pipe 71, and a drainage pump 72 in the drainage pipe 71. Since the flow rate adjusting valve 73 provided on the downstream side of the above is included, the flow rate of the filtrate sent from the filtrate storage tank 6 to the wastewater treatment facility 16 via the drainage pipe 71 can be adjusted. Therefore, the filtrate discharge line 7 can send an amount of filtrate corresponding to the treatment performance of the wastewater treatment facility 16 to the wastewater treatment facility 16.

In some embodiments, the gypsum slurry dehydration system 1 described above comprises the above-mentioned absorption liquid storage tank 17 configured to store the absorption liquid that is brought into gas-liquid contact with the exhaust gas in the flue gas desulfurization apparatus 20, and the filter cloth cleaning liquid. A water supply line 9 configured to send the liquid stored in the storage tank 8 to the absorption liquid storage tank 17 is further provided.

Since the amount of impurities adhering to the filter cloth 31 after the gypsum is discharged is small, the filter cloth cleaning liquid has a low impurity content even if it absorbs the impurities adhering to the filter cloth 31. A filtrate having a high impurity content may overflow from the filtrate storage tank 8 into the filter cloth cleaning liquid storage tank 8, but since it is diluted by the filter cloth cleaning liquid, it is stored in the filter cloth cleaning liquid storage tank 8. The liquid has a lower impurity content than the filtrate stored in the filtrate storage tank 6. According to the above configuration, the liquid stored in the filter cloth cleaning liquid storage tank 8 having a low impurity content is sent to the absorption liquid storage tank 17 via the water supply line 9, and the liquid is discharged to the flue gas desulfurization apparatus 20. It can be returned to the circulation system of the absorption liquid in the above and reused as the absorption liquid.

In some embodiments, the above-mentioned water supply line 9 has, as shown in FIG. 2, a water supply pipe 91 connected to the above-mentioned filter cloth cleaning liquid storage tank 8 and the above-mentioned absorption liquid storage tank 17, and a water supply pipe. Includes a water pump 92 provided in 91. The water supply pump 92 is configured so that the rotation speed is controlled according to the liquid level height H3 of the liquid stored in the filter cloth cleaning liquid storage tank 8.

In the illustrated embodiment, as shown in FIG. 2, the above-mentioned gypsum slurry dehydration system 1 is configured to acquire the liquid level height H3 of the liquid stored in the filter cloth cleaning liquid storage tank 8. A control device including a surface height acquisition device 93 and a rotation number indicating unit 941 configured to indicate the rotation number to the water supply pump 92 according to the liquid level height H3 acquired by the liquid level height acquisition device 93. 94 and are further provided.

Examples of the liquid level height acquisition device 93 include an infrared type liquid level sensor. The control device 94 is an electronic control unit for adjusting the rotation speed of the water supply pump 92, and is a CPU (processor) (not shown), a memory such as ROM or RAM, a storage device such as an external storage device, an I / O interface, and communication. It may be configured as a microcomputer including an interface or the like. Then, for example, each functional unit is realized by the CPU operating (for example, data calculation) according to the instruction of the program loaded in the main storage device of the memory. The control device 94 is configured to be able to send and receive signals to and from the water supply pump 92 and the liquid level height acquisition device 93. The water supply pump 92 is electrically controlled by a signal sent from the control device 94, and is configured to be driven or stopped and its rotation speed can be adjusted according to the signal. Examples of such a water pump 92 include a water pump having a built-in inverter motor or the like.

In the illustrated embodiment, the rotation speed indicator 941 instructs the water supply pump 92 to stop when the liquid level height H3 sent from the liquid level height acquisition device 93 does not reach the lower limit threshold value LH. .. Further, in the state where the water supply pump 92 is stopped, the rotation speed indicator 941 is driven by the water supply pump 92 when the liquid level height H3 sent from the liquid level height acquisition device 93 becomes equal to or higher than the lower limit threshold value LH. Instruct to do. Further, when the liquid level height H3 sent from the liquid level height acquisition device 93 is equal to or lower than the upper limit threshold value UH and equal to or higher than the lower limit threshold value LH, the rotation speed indicating unit 941 gives the water supply pump 92 the first rotation speed. Instruct to rotate by. When the liquid level height H3 sent from the liquid level height acquisition device 93 exceeds the upper limit threshold UH, the rotation speed indicator 941 uses a second rotation speed faster than the first rotation speed to the water supply pump 92. Instruct to rotate. The upper limit threshold value UH is set lower than a predetermined height H1 (height of the upper end of the weir 64).
In some other embodiments, the rotation speed indicating unit 941 continuously or stepwise instructs the water supply pump 92 to rotate as the liquid level height H3 sent from the liquid level height acquisition device 93 increases. It may be configured to increase the number.

Since not only the filter cloth cleaning liquid but also the filtrate overflowed from the filtrate storage tank 6 is sent to the filter cloth cleaning liquid storage tank 8, the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank 8 suddenly rises. There is a risk that the liquid will rise significantly and the liquid will overflow from the filter cloth cleaning liquid storage tank 8. According to the above configuration, the water supply line 9 includes a water supply pipe 91 connected to the filter cloth cleaning liquid storage tank 8 and the absorption liquid storage tank 17, and a water supply pump 92 provided in the water supply pipe 91. The water supply pump 92 is configured so that the rotation speed is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank 8. In this case, the rotation speed of the water supply pump 92 is controlled so that the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank 8 does not become excessively high, so that the liquid from the filter cloth cleaning liquid storage tank 8 Can be suppressed from overflowing.

FIG. 4 is an explanatory diagram for explaining another example of the gypsum slurry dehydration system according to the embodiment of the present disclosure.
In some embodiments, the water supply line 9 described above is provided in the water supply pipe 91, the water supply pump 92 provided in the water supply pipe 91, and the water supply pipe 91, as shown in FIG. A flow rate control valve 95 configured to be able to adjust the flow rate of the liquid sent from the cloth cleaning liquid storage tank 8 to the absorption liquid storage tank 17 is included. The flow rate control valve 95 is configured so that its opening degree is controlled according to the liquid level height H3 of the liquid stored in the filter cloth cleaning liquid storage tank 8. In this case, the rotation speed of the water supply pump 92 is kept constant.

In the illustrated embodiment, as shown in FIG. 4, the above-mentioned gypsum slurry dehydration system 1 has the above-mentioned liquid level height acquisition device 93 and the liquid level height H3 acquired by the liquid level height acquisition device 93. A control device 94A (94) including an opening degree indicating unit 942 configured to instruct the opening degree to the flow rate control valve 95 is provided.

The control device 94A is an electronic control unit for adjusting the opening degree of the flow control valve 95, and includes a CPU (processor) (not shown), a memory such as ROM and RAM, a storage device such as an external storage device, and an I / O interface. It may be configured as a microcomputer including a communication interface or the like. Then, for example, each functional unit is realized by the CPU operating (for example, data calculation) according to the instruction of the program loaded in the main storage device of the memory. The control device 94A is configured to be able to send and receive signals to and from the flow rate control valve 95 and the liquid level height acquisition device 93. The flow rate control valve 95 is electrically controlled by a signal sent from the control device 94A, and in response to the signal, the valve body of the flow rate control valve 95 is driven to open and close the flow path inside the flow rate control valve 95. The opening degree of the flow rate control valve 95 can be adjusted to a desired opening degree other than fully closed and fully open. Examples of such a flow rate control valve 95 include a control valve. In the illustrated embodiment, the flow rate control valve 95 is provided on the downstream side (absorption liquid storage tank 17 side) of the water supply pipe 91 with respect to the water supply pump 92.

In the illustrated embodiment, the opening degree indicating unit 942 is fully closed to the flow control valve 95 when the liquid level height H3 sent from the liquid level height acquisition device 93 does not reach the lower limit threshold value LH. Instruct. Further, when the flow rate control valve 95 is closed and the liquid level height H3 sent from the liquid level height acquisition device 93 becomes equal to or higher than the lower limit threshold value LH, the opening degree indicating unit 942 receives the flow rate control valve 95. Instruct to open. Further, when the liquid level height H3 sent from the liquid level height acquisition device 93 is equal to or lower than the upper limit threshold value UH and equal to or higher than the lower limit threshold value LH, the opening degree indicating unit 942 increases the opening degree of the flow rate control valve 95. Instruct the first opening. When the liquid level height H3 sent from the liquid level height acquisition device 93 exceeds the upper limit threshold value UH, the flow rate control valve 95 has an opening degree of the flow rate control valve 95 that is wider than the first opening degree. It is instructed to have an opening degree of 2 (for example, fully open). In some other embodiments, the opening degree indicating unit 942 instructs the flow rate control valve 95 continuously or stepwise as the liquid level height H3 sent from the liquid level height acquisition device 93 increases. The opening degree may be increased to increase the flow rate of the liquid passing through the flow rate control valve 95.

Further, in some other embodiments, the flow rate control valve 95 described above has two positions, fully closed and fully open, but may be configured so as not to be adjusted to an opening other than fully closed and fully open. The opening degree indicating unit 942 instructs the flow control valve 95 to open or fully close as the opening degree. In this case, the opening degree indicating unit 942 can increase the flow rate of the liquid passing through the flow rate control valve 95 by increasing the ratio of the period during which the flow rate control valve 95 is fully opened within a certain period. Examples of such a flow rate control valve 95 include a solenoid valve and the like.

As described above, not only the filter cloth cleaning liquid but also the filtrate overflowed from the filtrate storage tank 6 is sent to the filter cloth cleaning liquid storage tank 8, so that the liquid level of the liquid stored in the filter cloth cleaning liquid storage tank 8 is reached. There is a risk that the height will rise sharply and the liquid will overflow from the filter cloth cleaning liquid storage tank 8. According to the above configuration, the water supply line 9 includes the water supply pipe 91, the water supply pump 92 provided in the water supply pipe 91, and the flow rate control valve 95 provided in the water supply pipe 91. The flow rate control valve 95 is configured so that its opening degree is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank 8. In this case, the opening degree of the flow rate control valve 95 is controlled so that the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank 8 does not become excessively high, so that the filter cloth cleaning liquid storage tank 8 can be used as described above. It is possible to prevent the liquid from overflowing.

The present disclosure is not limited to the above-described embodiment, and includes a modified form of the above-described embodiment and a combination of these embodiments as appropriate.

The contents described in some of the above-described embodiments are grasped as follows, for example.

1) The gypsum slurry dehydration system (1) according to at least one embodiment of the present disclosure is
A gypsum slurry dehydration system (1) for dehydrating the gypsum slurry discharged from the flue gas desulfurization apparatus (20).
A transport device (3) having a transport belt (32) for transporting the gypsum slurry in a state of being placed on a filter cloth (31).
A filter cloth cleaning device (5) having a ejection portion (filter cloth cleaning liquid ejection portion 51) capable of ejecting the filter cloth cleaning liquid onto the filter cloth (31).
A filtrate storage tank (6) configured to store the filtrate separated from the gypsum slurry by the filter cloth (31), and
A filtrate discharge line (7) configured to send the filtrate stored in the filtrate storage tank (6) to a wastewater treatment facility (16) that performs a treatment for discharging the filtrate to the outside of the system. When,
The filter cloth cleaning liquid storage tank (8) different from the filtrate storage tank (6), and the filter cloth ejected from the ejection portion (filter cloth cleaning liquid ejection portion 51) to the filter cloth (31). A filter cloth cleaning liquid storage tank (8) configured to store at least the cleaning liquid is provided.

The gypsum slurry discharged from the flue gas desulfurization device absorbs impurities (for example, suspended solids such as combustion ash and soot removed from the exhaust gas and pollutants such as molten heavy metals) from the exhaust gas in the flue gas desulfurization device. There is. Then, in a dehydration treatment facility (for example, a transport device), impurities are separated from the gypsum together with the filtrate from the gypsum slurry. Further, the cake washing liquid used for washing the cake contains impurities such as metal ions such as magnesium (Mg), chlorine (Cl) and sodium (Na). Therefore, the cake cleaning solution sent to the filtrate storage tank as the filtrate after being used for cleaning the filtrate or cake separated from the gypsum slurry is compared with the filter cloth cleaning solution sprayed onto the filter cloth. High impurity content. Returning the filtrate having a high impurity content to the circulation system of the absorption liquid in the flue gas desulfurization apparatus is not appropriate because the content of impurities in the absorption liquid in the flue gas desulfurization apparatus increases. It is preferable that the filtrate having a high impurity content is discharged to the outside of the system after the wastewater treatment in the wastewater treatment facility.

According to the configuration of 1) above, the filtrate separated from the gypsum slurry and the cake cleaning solution used for washing the cake can be stored in the filtrate storage tank (6), and the filter cloth ejected to the filter cloth can be stored. The cleaning liquid can be stored in the filter cloth cleaning liquid storage tank (8). Then, the filtrate stored in the filtrate storage tank can be sent to the wastewater treatment facility (16) via the filtrate discharge line (7), and can be discharged to the outside of the system after the wastewater treatment in the wastewater treatment facility. In this way, the filtrate with a high impurity content and the filter cloth cleaning solution with a low impurity content are stored separately, and the wastewater sent to the wastewater treatment facility is stored in the filtrate storage tank. By limiting the filtrate to a high filtrate, the amount of wastewater sent from the dewatering facility for the gypsum slurry to the wastewater treatment facility can be reduced by the amount of the filter cloth cleaning solution. In addition, by reducing the amount of wastewater sent to the wastewater treatment facility, it is possible to suppress an increase in the size of the wastewater treatment facility and an increase in equipment cost.

2) In some embodiments, the gypsum slurry dehydration system (1) according to 1) above.
In the filtrate storage tank (6), among the filtrates stored in the filtrate storage tank (6), the filtrate exceeding a predetermined height overflows into the filter cloth cleaning liquid storage tank (8). It is configured as follows.

According to the configuration of 2) above, in the filtrate storage tank (6), among the filtrates stored in the filtrate storage tank, the filtrate exceeding a predetermined height exceeds the filter cloth cleaning liquid storage tank (8). It is configured to flow. Therefore, a filtrate other than the predetermined amount of filtrate that needs to be sent to the wastewater treatment facility (16) is sent to the filter cloth cleaning liquid storage tank (8) without going through complicated equipment such as a pump or level control. This can reduce the complexity and cost of equipment.
Further, for example, even when a filtrate exceeding the amount that can be treated by the wastewater treatment equipment (16) is supplied to the filtrate storage tank (8), the wastewater treatment equipment (16) is supplied from the filtrate storage tank (8). If only the amount of the filtrate that can be processed is sent to the filter, the remaining amount of the filtrate that exceeds the amount that can be processed naturally overflows into the filter cloth cleaning solution storage tank (8) and is stored in the filter cloth cleaning solution. Since it is stored in the tank (8), it is not necessary to make the wastewater treatment facility (16) a large facility with a margin, and it is possible to suppress the increase in the cost of the wastewater treatment facility (16).

3) In some embodiments, the gypsum slurry dehydration system (1) according to 2) above.
The filtrate discharge line (7) is
The drainage pipe (71) connected to the filtrate storage tank (6) and the wastewater treatment facility (16),
The drainage pump (72) provided in the drainage pipe (71) and
It is provided on the downstream side of the drainage pump (72) in the drainage pipe (71), and the flow rate of the filtrate sent from the filtrate storage tank (6) to the wastewater treatment facility (16) can be adjusted. Includes at least the flow control valve (73) provided.

According to the configuration of 3) above, the filtrate discharge line is located on the downstream side of the drainage pipe connected to the filtrate storage tank and the wastewater treatment facility, the drainage pump provided in the drainage pipe, and the drainage pump in the drainage pipe. Since the flow control valve provided is included, the flow rate of the filtrate sent from the filtrate storage tank to the wastewater treatment facility via the drainage pipe can be adjusted. Therefore, the filtrate discharge line can send an amount of filtrate corresponding to the treatment performance of the wastewater treatment facility to the wastewater treatment facility.

4) In some embodiments, the gypsum slurry dehydration system (1) according to 3) above.
In the flue gas desulfurization apparatus (20), an absorption liquid storage tank (17) configured to store an absorption liquid that is in gas-liquid contact with exhaust gas, and
A water supply line (9) configured to send the liquid stored in the filter cloth cleaning liquid storage tank (8) to the absorption liquid storage tank (17) is further provided.

Since the amount of impurities adhering to the filter cloth after the gypsum is discharged is small, the filter cloth cleaning solution has a low impurity content even if it absorbs the impurities adhering to the filter cloth. A filter medium having a high impurity content may overflow from the filter medium cleaning liquid storage tank to the filter cloth cleaning liquid storage tank, but since it is diluted by the filter cloth cleaning liquid, the liquid stored in the filter cloth cleaning liquid storage tank is The content of impurities is lower than that of the filtrate stored in the filtrate storage tank. According to the configuration of 4) above, the liquid stored in the filter cloth cleaning liquid storage tank having a low impurity content is sent to the absorption liquid storage tank 17 via the water supply line, whereby the liquid is flue-gas desulfurized. It can be returned to the circulation system of the absorption liquid in the above and reused as the absorption liquid.

5) In some embodiments, the gypsum slurry dehydration system (1) according to 4) above.
The water supply line (9) is
The water supply pipe (91) connected to the filter cloth cleaning liquid storage tank (8) and the absorption liquid storage tank (17), and
Including the water supply pump (92) provided in the water supply pipe (91).
The water supply pump (92) is configured so that the rotation speed is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank (8).

Since not only the filter cloth cleaning liquid but also the filtrate overflowed from the filtrate storage tank (6) is sent to the filter cloth cleaning liquid storage tank, the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank suddenly rises. There is a risk that the liquid will rise significantly and the above liquid will overflow from the filter cloth cleaning liquid storage tank. According to the configuration of 5) above, the water supply line includes a water supply pipe connected to the filter cloth cleaning liquid storage tank and the absorption liquid storage tank, and a water supply pump provided in the water supply pipe. The water supply pump is configured so that the rotation speed is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank. In this case, the rotation speed of the water supply pump is controlled so that the liquid level of the liquid stored in the filter cloth cleaning liquid storage tank does not become excessively high, so that the above liquid overflows from the filter cloth cleaning liquid storage tank. Can be suppressed.

6) In some embodiments, the gypsum slurry dehydration system (1) according to 4) above.
The water supply line (9) is
The water supply pipe (91) connected to the filter cloth cleaning liquid storage tank (8) and the absorption liquid storage tank (17), and
The water supply pump (92) provided in the water supply pipe (91) and
A flow rate control valve (95) provided in the water supply pipe (91) and configured to be able to adjust the flow rate of the liquid sent from the filter cloth cleaning liquid storage tank (8) to the absorption liquid storage tank (17). Including
The flow rate control valve (95) is configured so that the opening degree is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank (8).

As described above, not only the filter cloth cleaning liquid but also the filtrate overflowed from the filtrate storage tank (6) is sent to the filter cloth cleaning liquid storage tank, so that the liquid level of the liquid stored in the filter cloth cleaning liquid storage tank is liquid. There is a risk that the height will rise sharply and the above liquid will overflow from the filter cloth cleaning liquid storage tank. According to the configuration of 6) above, the water supply line includes the water supply pipe, the water supply pump provided in the water supply pipe, and the flow rate control valve provided in the water supply pipe. The flow rate control valve is configured so that its opening degree is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank. In this case, the opening of the flow rate control valve is controlled so that the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank does not become excessively high, so that the liquid overflows from the filter cloth cleaning liquid storage tank. Can be suppressed.

1 Gypsum slurry dehydration system 3 Transport device 31 Filter cloth 311 Supported part 312 Top surface 32 Transport belt 321 Top surface 322 Support part 33, 33A, 33B Drum 34 Motor 35 Guide roller 36 Dehydration part 37 Dehydration device 371 Dehydration chamber 372 Vacuum pump 373 Decompression Pipe 374 Vacuum tank 375 Liquid discharge pipe 4 Supply device 41 Supply part 42 Supply pipe 43 Gypsum discharge part 44 Cake cleaning device 45 Cake cleaning liquid ejection part 46 Cake cleaning liquid supply pipe 47 Pump 5 Filter cloth cleaning device 51 Filter cloth cleaning liquid ejection part 52 Cloth cleaning liquid supply pipe 53 Pump 54 Steam ejection device 55 Steam ejection part 56 Steam pipe 58 Filter cloth cleaning liquid receiving part 59 Filter cloth cleaning liquid discharge pipe 6 Filter liquid storage tank 61 Internal space 62 Inner side surface 63 Bottom surface 64 Dam 7 Filter liquid discharge line 71 Drainage pipe 72 Drainage pump 73 Flow control valve 8 Filter cloth cleaning liquid storage tank 81 Internal space 82 Inner side surface 83 Bottom surface 9 Water supply line 91 Water supply pipe 92 Water supply pump 93 Liquid level height acquisition device 94, 94A Control device 941 Rotation speed indicator 942 Opening indicator 95 Flow control valve 10 Exhaust gas cleaning system 11 Combustion equipment 12 Absorbent liquid supply line 121 Absorbent liquid supply pipe 122 Supply pump 13 Absorbent liquid circulation line 131 Absorbent liquid circulation pipe 132 Circulation pump 133 First branch 14 Absorption liquid extraction Line 141 Pipe 142 Adjusting valve 143 Second branch 15 Absorbent liquid return line 151 Absorbent liquid return pipe 16 Exhaust gas treatment equipment 161 First coagulation settling tank 162 Internal space 163 Second coagulation settling tank 164 Internal space 165 First coagulant addition line 166 Second coagulant addition line 167 Dam 168 Partition 17 Absorbent liquid storage tank 171 Internal space 20 Smoke exhaust desulfurization device 20A Absorption tower 21 Internal space 21A Gas-liquid contact part 21B Liquid pool part 22 Absorption tower body 221 Absorption liquid outlet 222 Nozzle penetration port 223 Absorption liquid supply port 224 Absorption liquid return port 23 Exhaust gas introduction port 24 Exhaust gas discharge port 25 Mist eliminator 26 Sprayer 261 Spray tube 262 Spray nozzle 263 Spray port 27 Oxidation gas supply device 271 Nozzle 272 Pump 273 Opening LH Lower limit threshold UH Upper limit threshold

Claims

A gypsum slurry dehydration system for dehydrating gypsum slurry discharged from a flue gas desulfurization apparatus.
A transport device having a transport belt that transports the gypsum slurry in a state of being placed on a filter cloth, and
A filter cloth cleaning device having a ejection portion capable of ejecting the filter cloth cleaning liquid onto the filter cloth, and a filter cloth cleaning device.
A filtrate storage tank configured to store the filtrate separated from the gypsum slurry by the filter cloth, and
A filtrate discharge line configured to send the filtrate stored in the filtrate storage tank to a wastewater treatment facility that performs a treatment for discharging the filtrate to the outside of the system.
A filter cloth cleaning liquid storage tank different from the filtrate storage tank, which is configured to store at least the filter cloth cleaning liquid ejected from the ejection portion onto the filter cloth, and a filter cloth cleaning liquid storage tank.
Gypsum slurry dehydration system.
According to claim 1, the filtrate storage tank is configured such that among the filtrates stored in the filtrate storage tank, a filtrate exceeding a predetermined height overflows into the filter cloth cleaning liquid storage tank. The gypsum slurry dehydration system described.
The filtrate discharge line
The drainage pipe connected to the filtrate storage tank and the wastewater treatment facility,
The drainage pump provided in the drainage pipe and
A claim that includes at least a flow rate adjusting valve provided on the downstream side of the drainage pump in the drainage pipe and configured to be able to adjust the flow rate of the filtrate sent from the filtrate storage tank to the wastewater treatment facility. 2. The gypsum slurry dehydration system according to 2.
An absorption liquid storage tank configured to store an absorption liquid that is in gas-liquid contact with exhaust gas in the flue gas desulfurization apparatus.
The gypsum slurry dehydration system according to claim 3, further comprising a water supply line configured to send the liquid stored in the filter cloth cleaning liquid storage tank to the absorption liquid storage tank.
The water supply line
The water supply pipe connected to the filter cloth cleaning liquid storage tank and the absorption liquid storage tank,
Including a water supply pump provided in the water supply pipe,
The gypsum slurry dehydration system according to claim 4, wherein the water supply pump is configured such that the rotation speed is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank.
The water supply line
The water supply pipe connected to the filter cloth cleaning liquid storage tank and the absorption liquid storage tank,
The water supply pump provided in the water supply pipe and
A flow rate control valve provided in the water supply pipe and configured to be able to adjust the flow rate of the liquid sent from the filter cloth cleaning liquid storage tank to the absorption liquid storage tank is included.
The gypsum slurry dehydration system according to claim 4, wherein the flow rate control valve is configured such that the opening degree is controlled according to the liquid level height of the liquid stored in the filter cloth cleaning liquid storage tank.