JP2022072965A - Filter, and individual particle removing method - Google Patents

Abstract

To provide a filtration technology of a chemical cleaning solution which can execute chemical cleaning of a boiler efficiently while suppressing cost.SOLUTION: A filter includes a filter cylinder. The filter cylinder includes a cylindrical inner cylinder in which a fluid can pass, and a filter which is arranged on an outer side of the inner cylinder so as to cover a peripheral surface of the inner cylinder, and can deform in a radial direction of the inner cylinder. An individual particle removing method removes individual particles adhering to the filter included in the filter cylinder. The method stops inflow of the fluid into the filter, and repeats differential pressure return operation for reducing a differential pressure of the filter as a pressure difference between an inflow side and an outflow side of the fluid.SELECTED DRAWING: Figure 4

Description

The present invention relates to a technique for filtering a chemical cleaning liquid at the time of chemical cleaning of a boiler.

In thermal power generation boilers, chemical cleaning is regularly performed to remove scale adhering to or accumulated in the heat transfer pipes and pipes of the water supply system of the thermal power generation boiler. In the chemical cleaning of thermal power generation boilers, a circulation path is installed between the equipment to be cleaned from the economizer to the steam water separator, and an acidic chemical cleaning solution (hereinafter referred to as chemical cleaning solution) is circulated in the circulation path. Removes the scale in the tube of these equipment to be cleaned.

During the chemical cleaning work, a part of the scale exfoliated from the pipe of the equipment to be cleaned becomes sludge in an undissolved state and mixes into the circulation path. For this reason, a filter that captures this sludge and reduces re-introduction to the equipment to be cleaned is provided downstream of the equipment to be cleaned in the circulation path. The filter comprises a filter, which captures sludge in the lotion passing through the filter.

When a large amount of sludge adheres to the filter, the differential pressure of the filter increases. In this case, the chemical cleaning is stopped, the filter is separated from the circulation path, and the filter is cleaned. Cleaning the filter of such a filter is time-consuming because it is performed by backwashing air blow or the like or disassembling and cleaning. Therefore, the chemical cleaning itself must be temporarily stopped during that time. Sludge that has settled and accumulated during the pause tends to remain in a deposited state without resurfacing when resumed. Further, during the stoppage, the circulation path is immersed in the acidic washing liquid, so that the contact time with the washing liquid becomes long, and there is a possibility of excessive washing.

As a method of avoiding temporary stop of chemical cleaning, for example, a bypass flow path that bypasses the filter is provided, and when a differential pressure exceeding a predetermined value is generated in the filter, the cleaning liquid is flowed through the bypass flow path, and a filter is inserted between them. There is a technique for exchanging (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-183902

In the technique disclosed in Patent Document 1, since there is no mechanism for capturing sludge while the bypass flow path is in use, sludge flows into the pipe of the device to be cleaned via the circulation path. In order to avoid this, there is a method of providing a spare filter in the bypass flow path. However, as described above, since it takes time to clean the filter, it is necessary to prepare a large number of spare filters, which increases the cost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a filtration technique for a chemical cleaning liquid that can efficiently perform chemical cleaning of a boiler while keeping costs down.

The present invention is a filter provided with a filter cylinder, wherein the filter cylinder is provided on the outside of the inner cylinder so as to cover a cylindrical inner cylinder through which a fluid can pass and a peripheral surface of the inner cylinder. It is characterized by comprising a filter that can be deformed in the radial direction of the inner cylinder.

Further, the present invention is a method for removing solid particles adhering to a filter having a filter tube in a filter provided with a filter tube, wherein the inflow of a fluid into the filter is temporarily stopped. The filter is characterized in that the differential pressure recovery operation for reducing the differential pressure, which is the pressure difference between the inflow side and the outflow side of the fluid, is repeated.

According to the present invention, chemical cleaning of a boiler can be efficiently performed while keeping costs down. Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is a system diagram of the water supply system and the steam system of the power plant which uses the thermal power generation boiler of embodiment of this invention. It is explanatory drawing for demonstrating the piping at the time of chemical cleaning of the thermal power generation boiler of embodiment of this invention. (A) is an external view of the filter of the embodiment of the present invention, and (b) and (c) are a cross-sectional view taken along the line AA'and a cross-sectional view taken along the line BB'of (a), respectively. (A) is an external view of the filtration tube of the embodiment of the present invention, and (b) is an explanatory view for explaining the state of filtration. (A) is an explanatory diagram for explaining a situation where sludge is accumulated on the filter according to the embodiment of the present invention, and (b) is an explanatory diagram for explaining a situation where sludge is separated from the filter, respectively, and (c) and (d). ) Is a graph showing the time change of the differential pressure applied to the filter. It is a flowchart of the chemical cleaning method of embodiment of this invention. (A)-(c) are explanatory views for explaining the filtration cylinder of the modification of embodiment of this invention. (A) to (d) are explanatory views for explaining sludge peeling in the filtration tube of the modification of the embodiment of this invention. (A)-(c) are explanatory views for explaining the filtration cylinder of another modification of embodiment of this invention. (A) is a flowchart of a chemical cleaning method of a modified example of the embodiment of the present invention, and (b) is a graph of a time change of a differential pressure in the modified example. It is explanatory drawing for demonstrating the piping at the time of chemical cleaning of the thermal power generation boiler of the modification of embodiment of this invention.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to this embodiment, and when there are a plurality of embodiments, the present invention also includes a combination of the respective embodiments.

[Overall configuration of power plant]
First, a power plant in which a thermal power generation boiler (hereinafter referred to as "boiler") according to the present embodiment will be described. The power plant includes an exhaust gas system through which combustion gas (exhaust gas) discharged from the boiler flows, a steam system through which steam generated by the boiler flows, and a water supply system through which the water restored by the condenser flows.

FIG. 1 is a diagram showing an example of a water supply system and a steam system of the power plant 101. As shown in this figure, the power generation plant 101 of the present embodiment rotates a turbine using a boiler 100 that burns fuel and generates steam (superheated steam) by the heat of the combustion, and the steam generated by the boiler 100. A steam turbine 160 (high pressure turbine 161, medium pressure turbine 162, low pressure turbine 163) that drives a generator to generate power, and a water supply line (mainly) that returns the exhaust steam from the steam turbine to water and supplies it to the boiler 100. A water supply pipe 216) is provided.

The boiler 100 includes an economizer (ECO) 129, a furnace water wall pipe 222, a brackish water separator 130, a superheater 140, and a reheater 150. The superheater 140 and the reheater 150 may be provided in a plurality of stages from the downstream to the upstream. For example, the superheater 140 has a three-stage configuration of a primary superheater 141, a secondary superheater 142, and a tertiary superheater 143. The brackish water separator 130 may not be provided.

The steam turbine 160 includes a high pressure turbine (HPT) 161, a medium pressure turbine (IPT) 162, and a low pressure turbine (LPT) 163, each of which performs a predetermined task for rotationally driving the generator 102.

On the main feed water pipe 216, there are a condenser 170, a condenser pump 181, a low pressure feed water heater (low pressure heater) 182, a deaerator 183, a water supply pump 184, and a high pressure feed water heater (high pressure heater). 185 and are provided.

In the power plant 101 having the above configuration, the economizer 129 preheats the supplied water by heat exchange with the combustion gas. The water preheated by the economizer 129 becomes a water-steam two-phase fluid by passing through the furnace wall pipe formed on the wall in the furnace water wall pipe 222. The water-steam two-phase fluid generated in the furnace water wall pipe 222 is sent to the brackish water separator 130 via the first connecting pipe 225 and separated into saturated steam and saturated water. Here, the saturated steam is guided to the superheater 140, and the saturated water is guided to the condenser 170 through the saturated water pipe 217.

The saturated steam separated by the steam water separator 130 is superheated by the superheater 140 by heat exchange with the combustion gas, and the generated superheated steam is introduced into the high-pressure turbine 161 via the main steam pipe 212. The main steam pipe 212 is provided with a main steam stop valve.

The steam that has performed the predetermined work in the high-pressure turbine 161 is guided to the reheater 150 via the low-temperature reheat steam pipe 213. The reheater 150 reheats the steam that has performed the predetermined work in the high pressure turbine 161. The steam superheated by the reheater 150 is supplied to the medium pressure turbine 162 and the low pressure turbine 163 via the high temperature reheat steam pipe 214, where they work and drive the generator 102.

The steam that has finished its work in the low pressure turbine 163 is introduced into the condenser 170 by the turbine exhaust pipe 215. The condensate condensed by the condenser 170 passes through the low pressure heater 182 by the condensate pump 181 together with the saturated water sent from the brackish water separator 130, and then sent to the deaerator 183 to remove the gas component in the condensate. Will be done. The condensate that has passed through the deaerator 183 is further boosted by the water supply pump 184, then fed to the high-pressure heater 185 to be heated, and finally returned to the boiler 100.

[Composition during chemical cleaning]
In the above-mentioned power plant 101, temporary pipes are periodically connected to chemically clean the predetermined equipment (equipment to be cleaned) of the boiler 100. The chemical cleaning is performed by stopping the operation of the boiler 100, closing the main steam stop valve installed in the main steam pipe 212, installing a temporary pipe, and circulating the chemical cleaning liquid in the equipment to be cleaned. For the temporary piping, for example, a port for connecting the temporary piping at the time of chemical cleaning (for example, a flange connection portion closed by a blind flange) is provided in advance in the connection destination pipe, and the port is opened for connection. do.

FIG. 2 is a diagram for explaining a temporary pipe installed for chemical cleaning of the boiler 100 when the brackish water separator 130 is not provided. In this figure, temporary pipes and the like are shown by broken lines. In this case, the economizer 129 of the boiler 100 and the furnace water wall pipe 222 are chemically cleaned as equipment to be cleaned.

At the time of chemical cleaning, first, a temporary pipe 311 is provided in order to supply the cleaning liquid into the equipment to be cleaned. The temporary pipe 311 is connected to, for example, the inlet of the economizer 129 and the furnace water wall pipe 222. A circulation passage is formed by the temporary pipe 311, the heat transfer pipe in the economizer 129, and the furnace water wall pipe 222, and the chemical washing liquid is circulated in the circulation passage to perform chemical cleaning.

The temporary pipe 311 is provided with a temporary circulation pump (cleaning pump) 312 for circulating the chemical washing liquid in the circulation path. The chemical washing liquid is circulated in the circulation path by the washing pump 312, and the scale adhering to the inside of the heat transfer pipe in the economizer 129 and the inside of the furnace water wall pipe 222 is removed.

A filter 400 is provided downstream of the cleaning pump 312 of the temporary pipe 311. The filter 400 removes scale sludge (solid particles) contained in the cleaning liquid from the equipment to be cleaned.

Further, the temporary pipe 311 is provided with a bypass pipe 321 so as to bypass the filter 400. At the portion (inlet pipe) of the temporary pipe 311 between the branch point with the bypass pipe 321 and the inlet of the filter 400, an inlet valve 351 joins the temporary pipe 311 with the bypass pipe 321 and the filter 400. An outlet valve 352 is provided in a portion (outlet pipe) between the outlet and the outlet. Further, the bypass pipe 321 is provided with a bypass valve 353.

At the time of chemical cleaning, by opening the inlet valve 351 and the outlet valve 352 and closing the bypass valve 353, the chemical washing liquid passes through the filter 400 and sludge is removed.

The chemical lotion is supplied from a chemical liquid tank connected to a supply pipe provided in the temporary pipe 311.

[Filter]
Next, the configuration of the filter 400 of the present embodiment will be described. The filter 400 of the present embodiment includes a large number of filtration cylinders in a cylindrical casing having an inlet and an outlet for the chemical washing liquid, and the chemical washing liquid is passed from the outside to the inside of the filtration cylinder to perform filtration. ..

FIG. 3A is an external view of the filter 400 of the present embodiment. 3 (b) is a cross-sectional view taken along the line AA'of FIG. 3 (a), and FIG. 3 (c) is a cross-sectional view taken along the line BB'of FIG. 3 (a).

As shown in this figure, the filter 400 includes a main body 410 and a conical hopper 430. Further, the main body 410 includes a plurality of hollow filtration cylinders 420 and a casing 411 that surrounds the filtration cylinders 420. Casing 411 is cylindrical and has a hemispherical lid-like portion at the top. Further, the casing 411 is provided with a fluid inlet (inflow port) 412 below the casing 411. Further, a fluid outlet (outlet) 413 is provided in the lid-shaped portion of the casing 411.

The hopper 430 is a sludge storage unit provided in the lower part of the main body portion 410 and temporarily stores sludge separated from each filtration cylinder 420. As shown in this figure, the hopper 430 is provided with a discharge port 431, and sludge that has been peeled off and temporarily stored is discharged from the discharge port 431.

FIG. 4A is an external view of the filtration tube 420. As shown in this figure, the filter cylinder 420 is a cylindrical filter element, and has a filter 422, an outer cylinder 423, and a hollow cylindrical inner cylinder 421 with a closed bottom and an open top (FIG. 4 (b)). See) and.

The outer cylinder 423 is provided coaxially with the inner cylinder 421 on the radial outer side of the inner cylinder 421, and forms a cavity region having a predetermined width in the radial direction of the inner cylinder 421 with the inner cylinder 421. Hereinafter, in the present specification, the radial direction of the inner cylinder 421 is simply referred to as the radial direction.

The filter 422 is provided in the outer cavity region of the inner cylinder 421 so as to cover the peripheral surface of the inner cylinder 421. Further, the filter 422 is provided so as to be elastically deformable in the radial direction. The filter 422 is, for example, provided with a locking member in the inner cylinder 421 and is locked to the locking member. The radial width of the cavity region is the width that the filter 422 arranged in this cavity region can be deformed.

The filter 422 captures the sludge in the chemical washing liquid flowing into the filter 400 and filters the chemical washing liquid. In the present embodiment, it is made of a material having a predetermined thickness in the radial direction and elastically deformable. The material used is, for example, a fibrous material such as cloth, paper, or synthetic resin. In terms of filtration performance, for example, a material having a passage hole of about 1 micron by combining a mesh-like material or the above-mentioned materials or by forming multiple layers may be used.

The inner cylinder 421 is provided to prevent over-shrinkage and over-deformation of the filter 422 due to pressurization. Further, the outer cylinder 423 is provided to prevent overexpansion and overdeformation of the filter 422 due to decompression. The inner cylinder 421 and the outer cylinder 423 are each formed of a material having high corrosion resistance and a predetermined strength, for example, resin or metal, and are composed of, for example, a punching plate having a large number of holes. To.

As will be described later, the outer cylinder 423 may have a coarser structure so that sludge peeled from the filter 422 does not adhere. Specifically, for example, a net, a hexagonal wire mesh, or the like may be used.

[Sludge removal method]
In the filter 400 having such a configuration, the lotion containing sludge flows from the outer cylinder 423 toward the filter 422 and the inner cylinder 421 as shown in FIG. 4 (b). Then, the sludge 510 is captured and accumulated in the outer peripheral portion of the filter 422.

As shown in FIG. 5 (a), when sludge 510 is accumulated in the filter 422, the filter 422 is clogged, and as shown in FIG. 5 (c), the pressure on the inflow side of the chemical washing liquid of the filter 422 is increased. , The differential pressure, which is the difference from the pressure on the outflow side, rises. In FIG. 5 (c) and FIG. 5 (d) described later, the horizontal axis is the time (t) and the vertical axis is the differential pressure (Pa). Due to this differential pressure, as shown in FIG. 5A, the filter 422 is elastically deformed in the radial direction. This elastic deformation occurs, for example, from a portion (locking portion) locked to the locking member.

At this time, as shown in FIG. 5D, when the differential pressure recovery operation for reducing the differential pressure and recovering the differential pressure in a short time is performed, the pressing force in the radial direction of the filter 422 is reduced at once. Due to this pressure fluctuation, as shown in FIG. 5B, the filter 422 is deformed in the opposite direction in the radial direction due to the restoring force of the elastic deformation of the filter, the filter support member, and the like. After that, the filter 422 deforms and vibrates in the radial direction with the locking portion as a node. The sludge adhering to the filter 422 is peeled off by the elastic deformation due to this restoring force and the subsequent vibration. Then, the peeled sludge falls to the hopper 430.

When the adhering sludge is peeled off, the filter 422 recovers its function, and accordingly, the filtering capacity of the filter 400 is also restored.

In the present embodiment, as the differential pressure recovery operation, for example, an operation of closing the inlet valve 351 and the outlet valve 352 and opening the bypass valve 353 is performed. As a result, the chemical washing liquid passes through the bypass pipe 321 instead of the temporary pipe 311 and the water pressure on the filter 422 in the filter cylinder 420 is reduced, and as a result, the differential pressure generated in the filter 422 is reduced. do. The inlet valve 351 and the outlet valve 352 do not necessarily have to be closed, but one of them may be closed. When only one is closed, the number of valve operations is reduced, so that the stop period of the filter 400 can be shortened.

Further, in the present embodiment, for example, this differential pressure recovery operation is performed when the differential pressure reaches a predetermined threshold value Pth.

In this embodiment, the return operation is performed immediately after the differential pressure recovery operation. The return operation is an operation of opening the inlet valve 351 and the outlet valve 352 and closing the bypass valve 353. The return operation is performed, for example, a few minutes after the differential pressure recovery operation. The period from the differential pressure recovery operation to the recovery operation is arbitrarily determined according to the time during which the sludge exfoliated from the filter 422 falls on the hopper.

[Sludge removal method]
The flow of chemical cleaning using the sludge removal method of the present embodiment will be described. FIG. 6 is a processing flow of a chemical cleaning flow using the sludge removing method of the present embodiment.

The inlet valve 351 and the outlet valve 352 are opened, the bypass valve 353 is closed (step S1101), and chemical cleaning is started (step S1102). During the chemical cleaning, the chemical cleaning liquid flows from the cleaning pump 312 to the economizer 129 through the filter 400 via the temporary pipe 311. Then, it circulates through the furnace water wall pipe 222 in the furnace 120 and to the cleaning pump 312 via the temporary pipe 311.

Further, during the chemical cleaning, the filter 400 removes the sludge from the chemical washing liquid by adhering the sludge 510 to the outer surface of the filter 422 of the filter cylinder 420. As sludge accumulates on the surface of the filter 422, the flow of the chemical washing liquid stagnates and the differential pressure rises.

The differential pressure is confirmed at predetermined time intervals, and when the differential pressure reaches the threshold value Pth (step S1103), the above-mentioned differential pressure recovery operation is performed (step S1104). As a result, the sludge adhering to the filter 422 is separated from the filter 422 and falls on the hopper 430. By peeling the sludge from the filter 422, there is nothing that hinders the flow of the chemical washing liquid, and the function of the filter 422 is restored.

Immediately after that, the inlet valve 351 and the outlet valve 352 are opened, the bypass valve 353 is closed (step S1105), and the process returns to step S1103 until the chemical cleaning is completed (step S1106), and the process is repeated.

As described above, the filter 400 of the present embodiment includes a plurality of filtration cylinders 420, and each filtration cylinder 420 covers the cylindrical inner cylinder 421 through which the fluid can pass and the peripheral surface of the inner cylinder 421. Is provided on the outside of the inner cylinder 421 and includes a filter 422 which is elastically deformable in the radial direction of the inner cylinder 421. Then, when the differential pressure reaches a predetermined threshold value Pth, the inflow of the chemical washing liquid into the filter 400 is stopped for a predetermined short period of time, and the differential pressure which is the pressure difference between the inflow side and the outflow side of the filter 422. Perform a differential pressure recovery operation to reduce the pressure.

As described above, in the present embodiment, the sludge adhering to the filter 422 can be peeled off and removed by the differential pressure recovery operation for a short time, and the function of the filter 422 can be restored. Since the bypass pipe 321 is used for a very short period of time, it is possible to minimize the mixing of sludge 510 into the circulation path of chemical cleaning. Therefore, the reliability of the boiler 100 is guaranteed.

Since the period for using the bypass pipe 321 is short, it is not necessary to prepare a spare filter 400. Further, since the bypass pipe 321 can be used for a short time, it is not necessary to stop the chemical cleaning and remove the filter 400 for cleaning. Therefore, the disassembly and cleaning work of the filter 400 is also unnecessary. Further, after removing the sludge 510 adhering to the filter 422 by peeling off, chemical cleaning can be continued. As a result, the period required for chemical cleaning can be shortened, and the cost can be suppressed. That is, according to the present embodiment, chemical cleaning can be efficiently performed while suppressing the cost.

Further, according to the present embodiment, it is possible to cope with the initial stage of chemical cleaning in which a large amount of sludge 510 is generated in a short time.

Further, the sludge removing method of the present embodiment can be applied and is versatile regardless of the structure of the boiler 100.

<Modification 1>
In the above embodiment, the filtration cylinder 420 includes an outer cylinder 423, and a filter 422 is arranged between the inner cylinder 421 and the outer cylinder 423. However, the outer cylinder 423 does not have to be provided.

<Modification 2>
Further, instead of the outer cylinder 423, a wire or a plate-shaped pressing member may be used. FIG. 7A shows an example of arrangement of the presser member 424 when the ring-shaped wire 425 is used as the presser member 424.

As shown in this figure, as the pressing member 424, a plurality of ring-shaped wires 425 are arranged at predetermined intervals in the axial direction of the filtration tube 420. FIG. 7 (b) is a diagram for explaining how the filter 422 is pressed by the presser member 424, and FIG. 7 (c) shows an axial portion of the filter cylinder 420 of FIG. 7 (b). It is a cross-sectional view. As shown in these figures, the pressing member 424 presses the filter 422 from the radial outside of the inner cylinder 421. Further, when the radial pressing is reduced, the pressing member 424 prevents the filter 422 from being over-expanded and over-deformed in the radial direction.

When sludge accumulates in the filter 422 and a predetermined differential pressure is reached, a differential pressure recovery operation is performed to reduce the differential pressure in a short time. Vibrate. As a result, the sludge accumulated in the filter 422 is peeled off. This situation is shown in FIGS. 8 (a) to 8 (d).

Here, FIGS. 8A and 8C are cross-sectional views in the axial direction and the radial direction, respectively, in a state where sludge 510 is accumulated in the filter 422. Further, FIGS. 8 (b) and 8 (d) show the axial direction and the diameter, respectively, when the filter 422 vibrates and then returns to the original state due to the elastic restoring force immediately after the differential pressure recovery operation is performed. It is a cross-sectional view of a direction. In FIGS. 8 (a) and 8 (b), the pressing member 424 is omitted.

According to this modification, the filter 422 is pressed by the pressing member 424 at predetermined intervals. Therefore, when the differential pressure recovery operation is performed, multi-mode vibration occurs in the filter 422, and sludge can be evenly separated from the filter 422.

In this case, the outer cylinder 423 does not have to be provided. Further, the wire 425 does not have to be ring-shaped as in the present modification. For example, the filter may be spirally wound around the outer circumference of the filter 422 at predetermined intervals.

<Modification 3>
Further, as shown in FIG. 9A, the support member 426 for supporting the plurality of pressing members 424 of the modification 2 may be further provided. The support member 426 is arranged, for example, along the axial direction of the filtration tube 420. Like the pressing member 424, the support member 426 also has a function of pressing the filter 422 from the outside of the inner cylinder 421. It also has a function of preventing the filter 422 from over-expanding and over-deforming when the pressure is reduced.

By configuring as in this modification, the filter 422 is constrained in both the longitudinal direction and the circumferential direction of the filter 422 as shown in FIGS. 9 (b) and 9 (c) when the pressure suddenly changes. Vibrate. That is, the filter 422 undergoes more complicated multi-mode vibration than the modified example 2, and sludge can be separated from the filter 422 more evenly and evenly than the modified example 2.

In addition, in the above-mentioned modification 2 and modification 3, the filter 422 may not be formed of a material having an elastic restoring force. In this case, during the differential pressure recovery operation, the filter 422 is deformed and vibrated by the deformation operation due to the elastic restoring force of the pressing member 424 and the support member 426 to peel off the sludge. Further, in this case, when the radial pressing is reduced, at least one of the pressing member 424 and the supporting member 426 is radially restored by the elastic restoring force, thereby expanding the filter 422 in the radial direction and exciting the vibration. , Prevents the filter 422 from being over-expanded and over-deformed in the radial direction.

Even when the filter 422 is made of a material having no elastic restoring force, the sludge pressed against the filter 422 by the differential pressure slides down to some extent because the differential pressure becomes substantially 0 by the differential pressure recovery operation. .. Here, when the pressing member 424 and the supporting member 426 are deformed and vibrated, the filter 422 also vibrates, the sludge is peeled off, and the sludge removability is improved.

<Modification example 4>
In the above embodiment, when the differential pressure reaches the upper limit (threshold value Pth), the differential pressure recovery operation is performed. However, the execution timing of the differential pressure recovery operation is not limited to this. For example, the filtration operation and the differential pressure recovery operation may be repeated at predetermined time intervals. It should be noted that this time interval is set shorter than the time when the differential pressure reaches the upper limit.

The flow of chemical cleaning in this case is shown in FIG. 10 (a). The same processing as in the above embodiment is designated by the same reference numeral.

As shown in this figure, in the present modification, as in the above embodiment, the inlet valve 351 and the outlet valve 352 are opened, the bypass valve 353 is closed (step S1101), and chemical cleaning is started. In this modification, when the washing is started, the time count is also started (step S2102). For example, the time counter T is set to 0.

Further, it is determined whether or not a predetermined time (Δt) has elapsed during the chemical cleaning (step S2103), and when the predetermined time has elapsed, the above-mentioned differential pressure reduction operation is performed regardless of the magnitude of the differential pressure. (Step S1104). Immediately after that, a return operation is performed (step S1105), the time counter is set to 0 (step S2107), the process returns to step S2103, and the process is repeated until the chemical cleaning is completed (step S1106).

The state of the change of the differential pressure in this case is shown in FIG. 10 (b). As shown in this figure, in this modification, the differential pressure is repeatedly reduced and increased at predetermined time intervals.

According to the present modification, as in the above embodiment, the sludge 510 adhering to the filter 422 is peeled off by the differential pressure recovery operation, the function of the filter 422 is restored, and the filtration capacity of the filter 400 is restored accordingly. do.

Further, in this modification, the differential pressure recovery operation and the recovery operation are repeated at a predetermined time interval set shorter than the interval for performing the differential pressure recovery operation in the above embodiment. Therefore, the period for which the bypass pipe 321 is used can be further shortened, and the amount of sludge 510 mixed in the circulation path can be suppressed. Further, since the differential pressure recovery operation is performed in a state where the amount of sludge 510 deposited on the filter 422 is small, the recovery degree of the filter 422 is also improved. These further improve the reliability of the boiler.

<Modification 5>
The bypass tube 321 may be equipped with a spare filter. FIG. 11 shows the configuration of the temporary piping at the time of chemical cleaning in this modified example. As shown in this figure, in this modification, the bypass pipe 321 is provided with an inlet valve 351a for bypass, a filter 400a, and an outlet valve 352b instead of the bypass valve 353.

In this modification, the filtration operation and the differential pressure recovery operation are alternately performed by the filter 400 provided in the temporary pipe 311 and the filter 400a of the bypass pipe 321 to continuously perform the filtration operation. Further, since filtration can be performed while passing through the bypass pipe 321, sludge does not enter the circulation path.

Therefore, in this case, the two filters can continue the chemical cleaning without the sludge getting into the circulation path. Therefore, the reliability of the boiler can be guaranteed while keeping the construction period short. In addition, there is no need to disassemble and clean the filter, and overall low-cost washing work can be realized.

100: Boiler, 101: Power plant, 102: Turbine, 120: Fire furnace, 129: Coal saver, 130: Steam water separator, 140: Superheater, 141: Primary superheater, 142: Secondary superheater, 143: Tertiary superheater, 150: reheater, 160: steam turbine, 161: high pressure turbine, 162: medium pressure turbine, 163: low pressure turbine, 170: water recovery device, 181: recovery pump, 182: low pressure heater, 183: Boiler, 184: water supply pump, 185: high pressure heater,
212: Main steam pipe, 213: Low temperature reheat steam pipe, 214: High temperature reheat steam pipe, 215: Turbine exhaust pipe, 216: Main water supply pipe, 217: Saturated water pipe, 222: Furnace water wall pipe, 225: First Contact tube,
311: Temporary pipe, 312: Cleaning pump, 321: Bypass pipe, 351: Inlet valve, 351a: Inlet valve, 352: Outlet valve, 352b: Outlet valve, 353: Bypass valve,
400: Filter, 400a: Filter, 410: Main body, 411: Casing, 412: Inlet, 413: Outlet, 420: Filtration cylinder, 421: Inner cylinder, 422: Filter, 423: Outer cylinder, 424: Presser member, 425: Wire, 426: Support member, 430: Hopper, 431: Discharge port,
510: Sludge

Claims (12)

A filter equipped with a filter tube,
The filter tube is
A cylindrical inner cylinder through which fluid can pass, and
A filter provided on the outside of the inner cylinder so as to cover the peripheral surface of the inner cylinder, and provided with a filter that is deformable in the radial direction of the inner cylinder. The filter according to claim 1.
The filter is a filter characterized by being elastically deformable. The filter according to claim 2.
The filtration cylinder further includes an outer cylinder arranged coaxially with the inner cylinder on the outer side in the radial direction of the inner cylinder.
The outer cylinder forms a hollow region with the inner cylinder, and the outer cylinder forms a hollow region.
The filter is a filter characterized in that it is provided in the cavity region. The filter according to claim 1 or 2.
The filtration cylinder further includes a ring-shaped pressing member that presses the filter from the radial outside of the inner cylinder.
A filter characterized in that a plurality of the presser members are arranged at intervals in the axial direction of the filter tube. The filter according to claim 4, wherein the filter is used.
The filter tube includes a support member that supports the plurality of presser members.
The support member is a filter characterized in that it is arranged along the axial direction of the filter tube. The filter according to claim 1.
The inner cylinder is a filter characterized in that it is formed of a punching plate. The filter according to claim 1.
The fluid is a chemical cleaning solution for the boiler of a power plant.
The filter is a filter characterized by filtering sludge of a scale contained in the chemical cleaning liquid and removed from the heat transfer tube of the equipment to be cleaned of the boiler by chemical cleaning. A method for removing solid particles, which is a method for removing solid particles adhering to a filter of the filter tube in a filter provided with a filter tube.
A method for removing solid particles, which stops the inflow of fluid into the filter and repeats a differential pressure recovery operation for reducing the differential pressure, which is the pressure difference between the inflow side and the outflow side of the fluid, of the filter. The method for removing solid particles according to claim 8.
The method for removing solid particles, wherein the filter is the filter according to any one of claims 1 to 7. The method for removing solid particles according to claim 8.
The differential pressure recovery operation is
At least one of the inlet valve provided in the inlet pipe connected to the inlet of the filter and the outlet valve provided in the outlet pipe connected to the outlet of the filter is closed, and the filter is bypassed. A method for removing solid particles, which comprises an operation of opening a bypass valve provided in a bypass pipe. The method for removing solid particles according to claim 8.
A method for removing solid particles, which comprises repeating the differential pressure recovery operation at predetermined time intervals. The method for removing solid particles according to claim 8.
A method for removing solid particles, which comprises performing the differential pressure recovery operation when the differential pressure exceeds a predetermined threshold value.

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