JPH0681610U - Strainer with built-in tank - Google Patents

Abstract

(57) [Summary] [Purpose] In the strainer built into the tank,
Even if the filter is clogged, a predetermined flow rate of liquid can be allowed to flow and foreign matter can be prevented from flowing out. [Structure] A strainer provided at an outlet 2a of a bottom pipe 2 of a tank 1 is provided with a cylindrical filter 3 extending upward from an inner wall surface of a tank surrounding the outlet 2a and having an opening 6a in the upper portion, and the opening 6a. The working plate 5 is housed in the cylindrical filter 3 so as to cover it, and the compressed spring 4 is arranged between the working plate 5 and the bottom of the tank 1, so that the differential pressure before and after the filter reaches a predetermined value. When it reaches, the spring 4 is compressed and the actuating plate 5 is moved to open the passage for the liquid.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a strainer with a built-in tank that is provided at the pipe outlet of various tanks that constitute a thermal power plant, a nuclear power plant, and the like.

[0002]

[Prior art]

 In various tanks such as deaerator storage tanks and heater drain tanks of thermal power and nuclear power plants, the liquid flowing through the system is temporarily stored in the tank and supplied to downstream equipment. The flow rate of the liquid supplied to is stable.

Residual foreign matter (foreign matter that has not been removed during plant construction, periodic inspection opening, etc.) may flow into the various tanks, such as the equipment and piping that make up the system. If it reaches the equipment on the further downstream side, there is a risk of damage due to collision with the heat exchanger thin tubes, clogging of the thin tubes, and damage due to collision with the rotating equipment. Therefore, as a plant operation protection function, as shown in FIG. 4, a strainer 3 is provided at the outlet of the pipe 2 at the bottom of the tank 1 to prevent foreign matter from flowing out of the tank 1.

Here, in the conventional strainer with a built-in tank, as shown in FIG. 5, the outlet 2a of the pipe 2 on the inner side of the tank 1 is formed by forming a wire mesh or a perforated plate into a tubular shape. It is only covered by the filter 3, and has only the function of blocking foreign matter larger than the mesh of the filter.

[0005]

[Problems to be solved by the device]

 The above-described conventional strainer with a built-in tank has the following problems and is not always suitable as a protective function in plant operation. That is, (1) when the filter is clogged due to the trapping of a large amount of foreign matter, its liquid-passing capacity is reduced (especially, when a film-like foreign matter such as a vinyl sheet piece is trapped by the filter, water passage The ability is significantly reduced). (2) If the liquid passing capacity of the filter decreases, the equipment on the downstream side may malfunction due to low flow rate (pump surging, etc.) or performance (output down due to decrease in boiler feed water flow rate, heat exchanger performance May occur). Further, in this case, there is a risk that the tank overflows because the discharged fluid flow rate decreases with respect to the fluid flow rate entering the tank. (3) When the filter is clogged, the pressure on the downstream side decreases and the differential pressure across the filter increases. If the rise in the differential pressure across the filter becomes excessive (≥ the design differential pressure of the filter), the filter may be deformed or damaged.

The present invention has been made to solve these problems.

[0007]

[Means for Solving the Problems]

 The strainer with a built-in tank of the present invention has taken the following measures.

(1) In a strainer with a built-in tank that is provided at the bottom pipe outlet of a tank that stores liquid and liquid to prevent the outflow of foreign matter, extends upward from the inner wall surface of the tank surrounding the pipe outlet inside the tank and extends upward. A tubular filter having an opening, an operating plate housed in the tubular filter so as to cover the upper opening of the tubular filter, and a compression arranged between the operating plate and the bottom of the tank It is characterized in that it has a spring.

(2) In the strainer with a built-in tank according to (1), when the differential pressure across the tubular filter reaches a predetermined value, the flow passage area of the gap formed between the upper portion of the tubular filter and the working plate is reduced. The spring constant of the vane is set so that it is almost equal to the total opening area of the tubular filter, and when the differential pressure across the tubular filter reaches the predetermined value, the upper part of the tubular filter and the working plate. The opening diameter of the upper opening of the tubular filter and the outer diameter of the operating plate are set so that the size of the gap formed between the and is almost equal to the mesh width of the tubular filter. And

[0010]

[Action]

 In the present invention of (1) above, when the tubular filter is clogged, the differential pressure across the tubular filter rises, but when the differential pressure acts on the operating plate, it is held by the operating plate. The coil spring is deformed by receiving the compressive force. When the coil spring is compressed and deformed, the actuating plate moves downward along with it, forming a gap flow path between the actuating plate and the upper part of the cylindrical filter. Is secured. Also, when the filter becomes more clogged and the differential pressure rises further, the amount of compressive deformation of the coil spring also increases and the gap flow passage becomes larger, so the amount of liquid passing from this flow passage tends to increase, so the filter The front-to-back differential pressure does not rise excessively.

When the spring is set in a free state, even if a slight differential pressure acts, the spring is compressed and deformed to form a flow path. As long as the differential pressure rises (fluid flow rate reduction) that does not cause the above, it is not necessary to dare to operate the operating plate as described above. Therefore, in the present invention of the above (1), the spring is set in advance. It is set by compressing with the force of, and the flow path is not formed by the spring being compressed and deformed unless the differential pressure that overcomes the force acts. Here, the constant compression force when setting the coil spring is the time when the differential pressure that is somewhat smaller than the differential pressure that causes the equipment to malfunction or deteriorate in performance or the design differential pressure of the filter is reached. Is determined so that the spring is compressed and deformed.

Further, if the spring constant of the coil spring is too large, a flow passage having a sufficient size for securing the liquid passing capacity of the filter is not formed. Will be leaked. In the present invention (2), when the differential pressure across the tubular filter reaches a predetermined value that can be tolerated, a flow passage having an area approximately equal to the total opening area of the tubular filter operates with the upper portion of the tubular filter. A coil spring with a spring constant that is formed between the plates is used to ensure a sufficiently large flow path. Further, when the front-back pressure of the tubular filter reaches the above-mentioned allowable value, the size of the gap formed between the upper portion of the tubular filter and the operating plate is determined by the misch width of the tubular filter (when a wire mesh is used for the filter. In this case, the opening diameter of the upper part of the tubular filter and the outer diameter of the working plate are set so as to be almost the same as the opening, and the hole diameter when using a perforated plate). As a result, the gap formed between the upper portion of the tubular filter and the operating plate is maintained within the mesh width of the tubular filter, and foreign matter is prevented from flowing out.

[0013]

【Example】

 A first embodiment of the present invention will be described with reference to FIGS. Reference numeral 1 denotes a tank in which a liquid such as water is stored, and an outlet 2a of a pipe 2 is opened inside the bottom of the tank. 3 is a cylindrical tubular filter made of a perforated plate having a large number of holes 3a, which is concentrically provided so as to surround the outlet 2a, extends upward from the inner wall surface of the bottom of the tank 1, and has its upper end. This part is composed of a ring-shaped holding plate 6 having a circular opening 6a.

Inside the cylindrical filter 3, a disc-shaped actuating plate 5 having a diameter larger than that of the opening 6 a is arranged so as to cover the opening 6 a, and between the actuating plate 5 and the bottom of the tank 1. A coil spring 4 which is initially compressed by a compressive force F _o is interposed in the. Therefore, the operating plate 5 is restrained from moving upward by the ring-shaped pressing plate 6, and is simultaneously supported by the upper end portion of the coil spring 4.

The spring constant K of the coil spring 4 is the flow passage area of the gap formed between the holding plate 6 and the operating plate 5 when the differential pressure of the liquid before and after the cylindrical filter 3 reaches a predetermined value. It is set to be substantially equal to the total opening area of the perforated plate of the shaped filter 3. The size of the gap formed between the holding plate 6 and the operating plate 5 when the differential pressure of the liquid before and after the cylindrical filter 3 reaches the above-mentioned predetermined value depends on the size of the hole 3a of the hole of the cylindrical filter 3. The opening diameter of the pressing plate 6 and the outer diameter of the operating plate 5 are set so as to be substantially equal to the hole diameter. The white arrows in FIGS. 1 and 2 indicate the flow of liquid.

In the present embodiment configured as described above, as shown in FIG. 2, the working plate 5 having the pressure receiving area A moves downward due to the action of the differential pressure ΔP of the liquid before and after the cylindrical filter 3. Receive load F = ΔP · A, F> F_O(F_O: Initial compression force) load F _O The coil spring 4 initially compressed by is further compressed, and the coil spring 4 having the spring constant K is compressed and deformed δ = (F−F_O) / K is generated, and a gap passage of size δ is formed between the outer diameter portion of the working plate 5 and the inner diameter portion of the upper opening of the cylindrical filter 3. Therefore, even if the tubular filter 3 is clogged and the differential pressure of the liquid before and after the tubular filter 3 rises, the fluid flows through the clearance channel and the fluid discharged from the tank 1 Flow rate does not decrease.

When the differential pressure of the liquid before and after the tubular filter 3 reaches a predetermined value (maximum value) that can be allowed by the system, the tubular filter 3 is provided between the holding plate 6 and the operating plate 5. The flow passage is formed with an area approximately equal to the total opening area of the tank. Even if all the holes of the cylindrical filter 3 are closed, the flow rate of the fluid discharged from the tank 1 is maintained at a predetermined value. In addition, the differential pressure of the liquid before and after the cylindrical filter 3 is prevented from further increasing.

Further, at this time, since the size δ of the gap between the pressing plate 6 and the operating plate 5 is set to be substantially equal to the hole diameter of the cylindrical filter 3, the outflow of foreign matter is prevented. can do.

A second embodiment of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment in that the cylindrical filter 3 is formed in a truncated cone shape with an open upper side, and an opening 3b at the upper end of the cylindrical filter 3 is formed in the cylindrical filter 3. The working plate 5 which is covered and restrained from moving upward is accommodated.

Also in this embodiment, the same operation and effect as those of the first embodiment can be obtained.

[0021]

[Effect of device]

 The present invention can bring the following effects.

(1) Even when the cylindrical filter is clogged due to a large amount of foreign matter trapped or the like, there is no problem due to a decrease in the liquid passing capacity. This prevents malfunctions (pump surging, etc.) and performance degradation (output down, heat exchanger performance degradation, etc.) due to flow rate reduction in the equipment on the downstream side. To be done. Further, since the flow rate of the discharged liquid is prevented from decreasing with respect to the flow rate of the liquid flowing into the tank, there is no risk of the tank overflowing. Further, even if the tubular filter is clogged, the rise in the differential pressure across the tubular filter does not exceed a predetermined value, so there is no risk of the tubular filter being deformed or damaged.

(2) Even when the tubular filter is clogged and the operating plate is opened, the size of the gap flow passage formed between the upper portion of the tubular filter and the operating plate is equal to the mesh width of the filter. Since they are almost the same, it is possible to prevent foreign matter from passing through the filter easily and prevent damage to downstream equipment or clogging of the thin tube.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing an operating state of the embodiment.

FIG. 3 is a vertical sectional view of a second embodiment of the present invention.

FIG. 4 is an overall view of a tank including a conventional strainer.

FIG. 5 is a vertical sectional view of a strainer incorporated in the conventional tank.

[Explanation of symbols]

 1 Tank 2 Piping 2a Piping Outlet 3 Cylindrical Filter 3a Cylindrical Filter Hole 3b Cylindrical Filter Opening 4 Coil Spring 5 Actuation Plate 6 Holding Plate 6a Holding Plate Opening

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 7305-4D B01D 35/14 101

Claims (2)

[Scope of utility model registration request] 1. A strainer with a built-in tank, which is provided at a bottom pipe outlet of a tank for storing liquid and liquid to prevent the outflow of foreign matter, and which surrounds the pipe outlet inside the tank, extends upward from an inner wall surface of the tank, and has an opening at an upper portion. A tubular filter having, a working plate housed in the tubular filter so as to cover the opening at the top of the tubular filter, and a compressed spring arranged between the working plate and the bottom of the tank. A strainer with a built-in tank that is characterized by having. 2. The flow passage area of the gap formed between the upper portion of the tubular filter and the operating plate is substantially equal to the total opening area of the tubular filter when the differential pressure across the tubular filter reaches a predetermined value. The spring constant of the spring is set, and the size of the gap formed between the upper portion of the tubular filter and the operating plate when the differential pressure across the tubular filter reaches the predetermined value is tubular. The strainer with a built-in tank according to claim 1, wherein the opening diameter of the upper opening of the cylindrical filter and the outer diameter of the operating plate are set so as to be substantially equal to the mesh width of the filter.