JPH04503555A - Pressure relief valve for pressure equalization between an enclosed space and the surrounding atmosphere - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A pressure relief valve for equalizing pressure between a closed space and the surrounding atmosphere. and the surrounding atmosphere. Such pressure relief A particularly important application for relief valves is on tankers for petroleum products and chemicals. , the following discussion and description will treat this application as a starting point, but the same principles can be applied to other Applications, e.g. stationary storage and transport tank applications for liquid petroleum products and chemicals It will be understood that the same applies to

A tank is filled with a specific volume of product per unit time, e.g. a volume measured in m”/h. When the pressure in the tank rises to the specified opening pressure, the pressure relief valve must be opened, and then the filling amount of product per unit time in the tank An amount of gas equivalent to the amount added to the amount of evaporation from the liquid surface must be blown out per unit time. Must be. The flow rate per unit time is determined by the flow resistance of the valve and therefore the pressure. that can be obtained without exceeding certain safety limits (adding that for evaporation). The maximum number of people blown out per unit time (subtracted) is called the pressure relief valve capacity; This capacity is thus equal to the maximum possible filling rate per unit time (e.g. m'/h). This is a measured value.

Closing to stop filling and the pressure in the tank to a predetermined value, i.e. slightly lower than the opening pressure When the pressure drops, the pressure relief valve closes. When unloading from a tank , the gas pressure in the tank will drop quickly. Pressure does not drop below predetermined safety limits It is recommended to use a vacuum valve to ensure this. This vacuum valve is the same as the pressure relief valve. They may be made separately or may be attached separately. In certain cases, For safety, an inert gas such as nitrogen is supplied to the free space above the liquid level in the tank. . Such gases must be kept at a specified pressure greater than atmospheric pressure and less than the opening pressure of the pressure relief valve. The pressure is maintained automatically. In this case as well, be prepared in case you fail to supply inert gas. It is better to use a vacuum safety valve instead.

If the ambient temperature increases or decreases during storage or transportation, the gas pressure in the tank will decrease. The forces rise and fall, which causes the pressure relief valve to in principle act as it does during filling and unloading. It opens and closes, but this is usually for a very short period of time, and the amount of air flow per unit time is are very few.

Similarly, vacuum safety valves and/or systems for supplying inert gas are It operates in the same way as when shipping.

Pressure relief valves for use on oil tankers are subject to strict regulations set out in international homologation regulations. must meet strict safety requirements. The most important of these safety requirements The necessary items are listed below.

1. Passage of flame from the outside into the tank through a pressure relief valve, generally a flash valve. Flash-backs must be reliably prevented. .

2. Safety against flashback when the valve is in the open state is high-speed airflow. In the case of so-called high-speed valves obtained by However, it must not fall below a predetermined minimum value, for example 30 m/sec.

3. In order to keep harmful flammable gas as far away as possible from areas where personnel are present, the , shall be in the form of a jet directed vertically upwards.

4. If the valve freezes, it can be removed quickly and easily, and the valve can be used normally, making it very effective. It must be possible to thaw the ice so that it can recover.

The pressure relief valve contemplated by the present invention has a valve housing with an upwardly directed outlet. The outlet is provided with a droplet-shaped body, and this droplet-shaped body has an impact on its lower side. Suitable for concentrating a rushing gas stream into an upwardly directed jet; The body is firmly connected to a lifting disc located below in the housing It is a type of pressure relief valve.

A pressure relief valve of this type is well known from U.S. Pat. No. 3,999,571; In the pressure relief valve disclosed in the patent, the lifting disc is an annular flat valve surface. This valve face is formed as a valve body with a valve seat in the valve housing that engages the valve body. The droplet-shaped body fits into the outlet opening of the valve with a small gap.

In this known valve, the outlet is always directed vertically upward with high velocity gas. occurs in the form of a jet, so the safety rules 1, 2 and 3 mentioned above are met. Furthermore , the guidance of the gas jet takes place without the use of surrounding guide surfaces, so that the shape Safety rule 4 is also met because the formed ice can be directly accessed from the outside. .

Relatively small amounts of ice formation should be avoided with manual checks that are always provided on pressure relief valves. Ice can be removed by simply lifting the valve with a check-1ift. Large deposits cannot be easily broken up because they are all on the outside of the valve. , then remove the last remaining one by lifting the valve as described above. can be done.

It is an object of the invention to achieve a higher lifting speed at the beginning of opening compared to known valves. Improved the known valve while maintaining the benefits of the known valve so that the increase in pressure is smaller It is to be.

To achieve this, the present invention utilizes a downward facing portion of the rounded surface of the droplet shaped body. forming an annular, approximately conical valve surface on the air outlet, thereby forming a mating valve surface at the mouth of the outlet. The lifting disc constitutes a valve body that closes against the valve seat. It has an outer diameter larger than the inner diameter and is secured by a free-passing slot in the closed position of the droplet-shaped valve body. It is characterized by being surrounded by people.

With this configuration, lifting pressure is applied to the underside of the droplet-shaped member in the valve seat at the beginning of opening. from a small area of the lifting disc to a larger area of the lifting disc, thereby , the old man lifting speed can be obtained.

However, the area of the lifting disc is limited even when the blowout volume is small. so that the blowing speed is always above a predetermined safety limit, e.g. 30 m/sec, Of course it must be kept within limits.

In an advantageous embodiment of the pressure relief valve according to the invention, the valve housing has a droplet-shaped body. and when lifting the lifting disc, the self-alignment around the lifting disc It has an internal shape that allows for a large passage area.

This ensures that even if the amount of air flow increases, the valve will remain open until it reaches its fully open state. The advantage is that lower pressures can be obtained than would otherwise be possible.

To reduce inert gas losses, it is important to obtain a particularly high degree of sealing on the valve when fully closed. If desired, according to the invention this is an annular elastic gasket with a lip. A lip is provided along the inner circumference of the valve seat, and this lip is in the closed position of the droplet-shaped body. , presses itself sealingly against the underside of the drop-shaped body.

The invention will be explained in detail below with reference to the accompanying drawings.

FIG. 1 is a side view, partially in section, of a pressure relief valve according to an embodiment of the invention; FIG. 2 is an enlarged partial cross-sectional view of the area adjacent the outlet of the pressure relief valve; FIGS. 3 and 4 illustrate a simple prototype of a pressure relief valve formed in accordance with the present invention. Tank pressure and blowing speed plotted against blowing amount per hour This is a characteristic curve representing

In the drawings, the reference number l is attached to the vertically oriented valve housing, which The valve housing has a flange 2 at its lower end, which flange 2 is connected to a tubular socket 4. It is bolted to the flange 3 of. At the lower end of the tubular socket 4 is an oil tank. or on a pressure relief pipe connected to one or more tank compartments. A flange 5 is formed at the end to which it can be bolted. In the illustrated embodiment, the socket 4 has a lateral opening 6 to which a vacuum safety valve 7 is connected. This vacuum safety valve is the invention , so it will not be explained in detail.

The valve housing has at its lower end a cylindrical wall section 8 which extends upwardly. A tapered wall section 9 is followed by a tapered wall section 9 in the direction, followed by a tapered wall section lO. The portion 1O terminates at the outlet 11 at the top of the valve housing.

A cap 12 is attached to the outlet, and a conical valve seat 13 is formed inside the cap. has been completed. The outlet 11 has a valve seat 13 and a seal when the valve is in the closed state. A droplet-shaped body 14 is provided with a conical valve surface 15 formed on the underside that engages to form a shape. It is placed.

In order to improve sealing performance, an annular elastic gasket 16 is placed inside the cap 12. The gasket preferably has a lip 17 that engages the underside of the droplet-shaped body 14. Ru.

A stem 18 is connected to the droplet-shaped body and extends downwardly through the housing. The stem includes an upper stem guide 19 of the valve housing and a lower stem guide of the socket 4. You will be guided at 20. The stem 18 supports a lifting disc 21, which The disk is arranged inside the cylindrical wall section 8 and has a diameter slightly smaller than the cylindrical wall section. As a result, a free passage slot 22 is formed around the lifting disc. vinegar A swing lever 24 is installed under the stem 18 for use in valve check lift. It is.

A compression spring 23 is interposed between the upper stem guide 18 and the lifting disc 23. It is set. Thus, the droplet-shaped body 13, the stem 18, and the lifting disk A structure with a is subjected to a closing force with a downward direction equal to . The weight of these parts themselves is reasonable. If these parts are made to provide a closing force, spring 23 can be omitted. May be omitted.

If a pressure in excess of atmospheric pressure develops in the tank, this pressure will leak through the slot 22. is transmitted into the space above the lifting disc 21, and therefore this lifter The same pressure is applied to the holding disc from above and below. Therefore, the lifting force is Created solely by the action of excess pressure on the underside of the drop-shaped body. This lift The lifting force is equal to the excess pressure multiplied by the cross-sectional area of the outlet inside the valve seat.

When the lifting force exceeds the closing force mentioned above, the valve opens. This occurs at a given tank pressure. Koru. The weight of the droplet-shaped main body 14, stem 18, and lifting disc 21 is The opening pressure preset by determining the weight load and/or the compression spring 2 It can be supplemented by adding 3. Blowing starts when the valve opens , the pressure acting on the upper side of the lifting disc decreases, and the net lifting force becomes The edge is equal to the tank pressure multiplied by the area of the lifting disc. lifting Since the area of the holding disc is larger than the area of the outlet, the lifting force is increased and this This increases the lifting speed and therefore the blowing volume per unit time.

When the valve is lifted further, the lifting disc 21 moves in the area of the diverging wall section 9. area, which further increases the blowout amount.

The overall dimensions are plotted against the blowout amount F per unit time for a given application. An appropriate characteristic curve can be obtained for the tank pressure PT and the blowing speed DV. The dimensions must be as follows.

Examples of such characteristic curves are shown in FIGS. 3 and 4.

As is clear from Figure 3, the tank pressure PT opens when the blowout amount F is small. Increases beyond the release pressure PO. This situation occurs immediately after the valve opens, but Due to the opening, the tank pressure remains at the maximum permissible value PT even when the opening pressure PO is relatively high. It is kept within max. When the flow rate increases, the tank pressure drops again and the valve closes completely. The value gradually approaches the value of the balloon when it is open, that is, the value shown by the dotted line in the figure.

When the blowout amount is continuously increased, the tank pressure further increases until the tank pressure reaches the value P. When Tmax is reached, the blowout amount reaches the maximum allowable value, that is, the capacity C of the pressure relief valve. Ta During tank filling, the filling amount per unit time after deducting evaporation remains below the above value. If the tank is in a substantially safe area and protected from explosion. This is because, as mentioned above, the blowout volume as a result of the temperature rise is It can also be applied during transportation, as it can be expected to be significantly lower than

By changing the dimensions, we can produce various pressure relief valves with the same structure but different capacities. can.

The blowing speed DV is very large when the blowing amount F is small, and then Figure 4 shows that as the amount increases, it decreases to the minimum value and then increases again. it is obvious. This minimum value was established to avoid flashbacks. It is higher than the above-mentioned minimum blowing velocity DVmin, for example 30 m/sec.

When the valve is in the closed position, the valve face 15 of the droplet-shaped body 14 and the gasket 16 are provided. A very high degree of sealing is obtained due to the engagement with the valve seat 13 which has been closed.

If the gasket [5] is damaged or Valve sealing prevents flashbacks from occurring even in case of complete destruction Therefore, safety rule 1 stated at the beginning of this specification is sufficient for the valve to be in the closed position. is satisfied even if

Absolute airtightness can never be achieved by interengaging metal surfaces, and conical valve seats and For axially guided discs, the leakage is slightly less than when the disc is flat. We have to expect it to get bigger. However, the gasket In the pressure relief valve according to the invention, gas leakage in the closed position of the valve is This occurs at a large blowing velocity due to the small area, and is caused by the aerodynamic effect of the droplet shape body. oriented vertically upwards. Furthermore, the pressure inside the tank must not exceed atmospheric pressure. between the valve seat and the droplet-shaped member to make flashback impossible in the first place. The annular engagement surface is given a width such that cooling in the leakage path extinguishes the flame. available. Therefore, gasket 16 can normally be installed without major drawbacks. Although it can be omitted, if an inert gas environment is maintained in the tank, the gasket 16 is omitted. Useful for reducing active gas losses.

When the valve is frozen, thawing can be performed as described above.

DVm/sek Heisei Year Month Day 1. Indication of patent application PCT/DK 901000503, patent applicant Name Serensen Emil Ahlestrap 4, Agent Address: 3-3-1 Marunouchi, Chiyoda-ku, Tokyo Telephone: (3211) 8741 5. Date of submission of written amendment: February 12, 1991 March 19, 1991 The pressure relief valve contemplated by the invention is of the type mentioned in the prior art part of claim 1. It is a force relief valve.

A pressure relief valve of this type is well known from U.S. Pat. No. 3,999,571; In the pressure relief valve disclosed in the patent, the lifting disc has a generally conical valve surface. This valve face is formed as a valve body with a valve seat in the valve housing that engages the valve body. The droplet-shaped body fits into the outlet opening of the valve with a small gap.

In this known valve, the outlet is always directed vertically upward with high velocity gas. occurs in the form of a jet, so safety rules 1.2 and 3 above are met. Furthermore , the guidance of the gas jet takes place without the use of surrounding guide surfaces, so that the shape Since it is possible to directly approach the ice that has formed from the outside, safety rule 4 is also met. .

Relatively small amounts of ice formation should be avoided with manual checks that are always provided on pressure relief valves. F) It can be removed by simply lifting the valve with (check-1ift). Large ice deposits can be easily broken up because they are all on the outside of the valve. and then remove the last remaining by lifting the valve as described above. can do.

It is an object of the invention to achieve a higher lifting speed at the beginning of opening compared to known valves. Improved the known valve while maintaining the benefits of the known valve so that the increase in pressure is smaller It is to be.

To achieve this, the invention has the features set out in the characterizing part of claim 1.

With this configuration, lifting pressure is applied to the underside of the droplet-shaped member in the valve seat at the beginning of opening. from a small area of the lifting disc to a larger area of the lifting disc, thereby , the old man lifting speed can be obtained.

However, in the area of the lifting disk, the compression spring 23 has a small blowout amount. It is interposed between the upper stem guide 19 and the lifting disk 21. write and has a droplet-shaped body 14, a stem 18, and a lifting disc 21. , the structure called a blowout control member in this specification applies all of this structure to the compressive force of the spring 23. subject to a downward closing force equal to the total weight of the parts plus the total weight of the parts.

These parts are designed such that their own weight provides adequate closing force. If so, the spring 23 may be omitted.

If a pressure in excess of atmospheric pressure develops in the tank, this pressure will leak through the slot 22. is transmitted into the space above the lifting disc 21, and therefore this lifter The same pressure is applied to the holding disc from above and below. Therefore, the lifting force is Created solely by the action of excess pressure on the underside of the drop-shaped body. This lift The lifting force is equal to the excess pressure multiplied by the cross-sectional area of the outlet inside the valve seat.

When the lifting force exceeds the closing force mentioned above, the valve opens. This occurs at a given tank pressure. Koru. The weight of the droplet-shaped main body 14, stem 18, and lifting disc 21 is The opening pressure preset by determining the weight load and/or the compression spring 2 It can be supplemented by adding 3. Blowing starts when the valve opens , the pressure acting on the upper side of the lifting disc decreases, and the net lifting force becomes It is equal to the tank pressure multiplied by the area of the lifting disc. lifting Since the area of the holding disc is larger than the area of the outlet, the lifting force is increased and this This increases the lifting speed and therefore the blowing volume per unit time.

When the valve is lifted further, the lifting disc 21 moves in the area of the diverging wall section 9. range, thereby further increasing the blowout amount.Claim ■ collides with the valve housing (1) with the upwardly directed outlet (11) on the lower side; said outlet suitable for concentrating the gas flow into an upwardly directed jet; (11) is located at a lower height within the droplet-shaped body (14) and housing (1). a lifting disc connected to said droplet-shaped body (14) arranged in the (21) and a blowout control member (14, 18, 21), The control member has a generally conical valve adapted to close against a mating valve seat (13). for equalizing the pressure between the closed space and the surrounding atmosphere, which is formed with a surface (15). In the pressure relief valve for Said conical valve surface (15) is rounded to that of said droplet-shaped body (14). The droplet-shaped body is formed on the downwardly facing part of the surface, thereby forming a valve body. and the meshing valve seat (13) is provided at the mouth of the outlet (11), The lifting disk (21) has an outer diameter larger than the inner diameter of the valve seat (13). have, The lifting disc (21) passes freely through the droplet-shaped valve body (14) in the closed position. A pressure relief valve, characterized in that it is surrounded by a slot (22).

2. The valve housing (1) includes a droplet-shaped body (14) and a lifting disc. Free passage around the lifting disc (21) when lifting the disc (21) 2. The pressure relief valve of claim 1, having an internal feature of increased area.

3. An annular elastic gasket (16) having a lip (17) is attached to the inner periphery of the valve seat (13). The lip is provided along the droplet shape of this international research report. international search report PCT/DK 90100050

Claims (3)

[Claims] 1. It has a valve housing (1) with an upwardly directed air outlet (11), said air outlet The mouth is provided with a droplet-shaped body (14), the droplet-shaped body colliding with the underside of the droplet-shaped body (14). It is suitable for concentrating a gas flow into an upwardly directed jet, and is suitable for The main body (14) has a lifting disc (21) provided below within the housing. ) for pressure equalization between the enclosed space and the surrounding atmosphere. In the pressure relief valve, said droplet-shaped body (14) has a rounded surface. An annular, substantially conical valve surface is formed in the downwardly directed portion, thereby opening the air outlet (1 1) constitutes a valve body adapted to close against the engaging valve seat (13) of the mouth; The lifting disk (21) has an outer diameter larger than the inner diameter of the valve seat (13), Surrounded by a free passage slot (22) in the closed position of the droplet-shaped valve body (14). pressure relief valve. 2. The valve housing (1) includes a droplet-shaped body (14) and a lifting disc. Free passage around the lifting disc (21) when lifting the disc (21) 2. The pressure relief valve of claim 1, having an internal feature of increased area. 3. An annular elastic gasket (16) having a lip (17) is attached to the inner circumference of the valve seat (13). , said lip being self-contained in the closed position of the droplet-shaped body (14). 2. The droplet-shaped body (14) is adapted to form a seal on the underside of the droplet-shaped body (14). Pressure relief valve included.