JP3313806B2 - Backfire arrestor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gas welding using a combustible gas such as acetylene gas, liquefied natural gas and hydrogen gas.
The present invention relates to a device for preventing a backflow accident of a fire caused by flashback, which may occur when performing gas cutting or gas heating.

[0002]

2. Description of the Related Art A conventional flashback arrestor is disclosed, for example, in Japanese Utility Model Publication No. Sho 63-21840. This flashback prevention device also has a check valve and a fire-extinguishing filter arranged in a casing. When a flashback occurs, the check valve prevents the gas pressure from going back and a fire-extinguishing filter is used. It has a structure to extinguish a flashback.

[0003]

The conventional flashback arrestor as described above cools and extinguishes the flashback that has progressed from the secondary side of the flashback arrestor when passing through a fire extinguishing filter. is there. However, in the conventional flashback arrestor, since the flow path between the fire extinguishing filter and the fuel gas outlet of the flashback arrestor is arranged in the forward direction with respect to the direction of progression of the flashback, its traveling speed and traveling speed are The temperature did not decrease and the fire extinguishing filter was in direct contact.

[0004] Therefore, the performance of the flashback arrestor greatly depends on the fire extinguishing filter itself, and the material such as stainless steel mesh used for the fire extinguishing filter must have a high density and a large area. There have been problems such as a decrease in performance and a large flashback prevention device itself.

Accordingly, an object of the present invention is to provide a structure for assisting the extinguishing of a flashback on the secondary side of the flashback prevention device,
An object of the present invention is to provide a small-sized flashback prevention device that reduces the burden on a fire-extinguishing filter when extinguishing a flashback, thereby having excellent flow characteristics.

[0006]

In order to solve the above problems, a flashback arrestor according to the present invention comprises a casing, a fire extinguishing filter, and each inner cylinder having a plurality of inner cylinders fitted inside or outside a fire extinguishing filter. Forming a plurality of spaces between, and forming a reversing path that connects the plurality of spaces in the longitudinal direction and turns the traveling direction of flashback between the fire suppression filter and the fuel gas outlet of the casing. I have.

[0007]

According to the flashback preventer described above, the flashback that has progressed advances into the casing from the fuel gas outlet of the flashback preventer. At this time, the flashback must pass through a reversal path formed between the inner cylinders in the casing. The reversing path guides the flashback in the direction opposite to the traveling direction. The flashback reaches the fire extinguishing filter after the power is greatly reduced by the reversing path.

[0008] That is, flashback reverses the traveling direction at least once on the reversal path, thereby reducing the pressure due to ignition and the traveling speed thereof. Further, the reversing path increases the traveling distance to the fire extinguishing filter, and diffuses the ignition heat of the flashback while reaching the fire extinguishing filter.

[0009]

Next, an embodiment of a flashback arrestor according to the present invention will be described with reference to the drawings. FIG. 1 is a side cross-sectional view of a part of a flashback arrestor of the present invention, and FIGS. 2A and 2B are explanatory views showing the operation of the flashback arrestor of this embodiment. .

First, the flashback arrestor 1 is made of acetylene gas,
A fuel gas such as natural gas or hydrogen gas is passed from a primary side A on the left side of FIG. 1 to a secondary side B on the right side of FIG. 1, and the primary side A is supplied to a gas supply device such as a distributor. The secondary side B is used by being connected to a gas combustion device such as a cutting torch. The check valve 1 is provided with a check valve 3 for preventing back flow of fuel gas in the center of a casing 2 and a cylindrical fire filter 4 closer to the secondary side B than the check valve 3. ing.

The casing 2 is provided with a gas flow port F1 having a gas inlet F1 in consideration of the assembling process of the flashback arrestor 1 and in order to provide a plurality of types of flashback arrestors 1 which differ depending on the type and use of the fuel gas. Formed from a supply port 20 on the road primary side A, a first casing 21 having a lock mechanism, a second casing 22 at the center, and a third casing 23 on the gas flow path secondary side B having a gas outlet F8. Is done. These casing members 20, 21, 22, 23 are screwed together with screws cut at their ends, and form an airtight and integral casing 1 using an O-ring.

The check valve 3 is formed by fitting a first cylindrical body 31 having a bottom into a second cylindrical body 32 also having a bottom so that the openings thereof are aligned with each other. A ring-shaped packing 30 is attached to the outside of 31. The first cylindrical body 32 has a fuel gas flow hole F3 formed on the peripheral side near the bottom thereof, and the second cylindrical body 32 has an F2 communicating with the inlet F1 of the casing 2 on the peripheral side. When,
The flow hole F communicating with the flow hole F3 of the first cylindrical body 31
4 are formed. A spring 3 for urging the first cylindrical body 31 in the direction of the second cylindrical body 32 is provided on the bottom of the first cylindrical body 31.
3 are arranged.

Therefore, when the check valve 3 is operated, the first cylindrical body 31 is biased by the spring 33 so that the second cylindrical body 3
2, the packing 30 comes into close contact with the inner side surface of the second cylindrical body 32, and the flow holes F3 and F
The structure is configured to shut off the space between the four and prevent backflow of the fuel gas.

The fire extinguishing filter 4 is a cylindrical body, and is fitted inside the third casing 23 with a gap, while being fixed inside the second casing 22. The fire extinguishing filter 4 is formed of, for example, a porous material such as a stainless steel mesh, and allows the fuel gas to flow therethrough. Further, inside the fire extinguishing filter 4, a first inner cylinder 5 and a second inner cylinder 6 having a bottom are further double-fitted with respective gaps.

A space is formed between the third casing 23, the fire extinguishing filter 4, the first inner cylinder 5, and the second inner cylinder 6 by loose fitting. A gas flow path primary side A is between the fire extinguishing filter 4 and the third casing 23, and a gas flow path secondary side B is between the fire extinguishing filter 4 and the first inner cylinder 5.
Further, the third casing 23 and the second inner cylinder 6 are connected to each other on the gas flow path primary side A, and a cylindrical gas flow path is formed therebetween.

That is, a fuel gas flow space F5 is formed between the inner surface of the fire extinguishing filter 4 and the outer surface of the first inner cylinder 5, and this space communicates with the flow hole F4. A fuel gas circulation space F6 is provided between the outer surface of the fire extinguishing filter 4 and the inner surface of the third casing 23, and a fuel gas is provided between the inner surface of the first inner cylinder 5 and the outer surface of the second inner cylinder 6. A reversing path R for turning the gas flow direction is formed. Further, on the gas passage secondary side B of the second inner cylinder 6, a fuel gas circulation hole F7 that connects the reversing path R to the inside of the second inner cylinder 6 and further to the outlet F8 is opened. ing. As described above, the backfire prevention device 1 is formed by these circulation holes, the circulation spaces F2 to F7, and the reversing path R.
Inside, a flow path from the fuel gas inlet F1 to the outlet F8 is formed.

The flashback prevention device 1 has a lock valve mechanism 7 for completely stopping gas supply when a flashback occurs, in addition to the check valve 3. The lock valve mechanism 7 includes a first cylinder 1
, A packing 71 provided on the outer periphery near the bottom of the second cylindrical body 32 constituting the check valve 3, and a holding member opened on the side surface of the first casing 21. It has a lock ball 73 disposed in the hole 72 and a reset cover 74 fitted on the outside of the first casing 21.

A spring 75 is disposed between the inner surface of the first casing 21 and the flange of the second cylindrical body 32 so as to urge the second cylindrical body 32 toward the gas passage secondary side B. On the outer periphery of the second cylindrical body 32, a flange 76 for receiving a pressure in the opposite direction is formed. The diameter of the lock ball 73 is larger than the thickness of the peripheral side plate of the second cylindrical body 32, and the reset cover 7 is adjusted to the height protruding from the holding hole 72.
4 has a first recess 77a on the inner surface and a second cylindrical body 31.
A second recess 77b is formed on the outer side surface of the second recess 77b. The reset cover 74 is urged toward the gas flow path primary side A by a spring 78 disposed inside, but normally the lock ball 73 enters the first recess 77 a and the reset cover 74.
Is restrained.

A green status display band 79a is wound around the outer surface of the first casing 21, and a red status display band 79b is wound around the outer surface of the supply port 20. The reset cover 74 is movably disposed so as to cover one of the status display bands 79a and 79b. However, as described above, the lock ball 73 prevents the movement, and in a normal state, the green state identification display band. 79 is exposed.

The operation of this embodiment will be described with reference to FIGS. 1, 2 (A) and 2 (B). First, in the normal state shown in FIG. 1, the lock valve mechanism 7 is opened by the bias of the spring 75, and also in the check valve 3, the inflow pressure of the fuel gas is opposed to the bias of the spring 33. First cylindrical body 3
1 is released by pressing 1.

That is, as shown in FIG. 1, a normal fuel gas flow path has a check valve 3 and a lock valve mechanism 7 between the fuel gas inlet F1 and the flow hole F2, and between the flow holes F3 and F4.
Is opened, and the primary side A and the secondary side B of the gas flow path communicate with each other. In this state, the fuel gas flows from the gas inlet F1 on the primary side A of the flow path, and
2, F3 and F4 to reach the distribution space F5. Then, after passing through the fire extinguishing filter 4, it flows out of the outlet F8 through the circulation space F6, the reversing path R, and the circulation hole F7.

Next, the operation when the fuel gas flows backward will be described with reference to FIG.
Will be described. A device such as a torch connected to the gas flow path secondary side may not operate due to clogging or the like. At this time, a backflow of the fuel gas occurs.

In this state, the pressure relationship between the fuel gas on the primary side A and the secondary side B of the gas flow path changes. That is,
In a normal state, the gas pressure on the primary side A is higher than the gas pressure on the secondary side B, and the fuel gas flows from the primary side A to the secondary side B.
When the fuel gas flows backward, the gas pressure on the secondary side B increases and the pressure difference between the primary side A and the secondary side B decreases.

Then, in the normal state, the first cylindrical body 31 which has moved to the primary side A against the bias of the spring 33 due to the fuel gas pressure,
The spring 33 moves to the secondary side B by the urging. Then, the packing 30 externally fitted to the first cylindrical body 31 comes into contact with the inner flange 32a of the second cylindrical body 32, and shuts off between the flow holes F3 and F4.

As described above, in this fuel gas backflow state, the check valve 3 is operated, and the secondary side B of the flashback prevention device 1 is operated.
From the fuel gas to the primary side A is prevented. Since the check valve 3 is operated by a change in the pressure difference between the primary side A and the secondary side B, when the reverse flow state is eliminated, the check valve 3 is automatically opened again, and the fuel gas flows in the forward direction. start.

Further, the operation when a flashback occurs will be described with reference to FIG. Following the above-described backflow of the fuel gas or alone, an accident may occur in which a combustion fire such as a torch leaves the grate and proceeds in the gas supply path in the reverse direction.

The flashback that has progressed first enters the device from the outlet F8 of the flashback prevention device 1, and enters the reversing path R via the circulation hole F6. The flashback that has entered the reversing path R further reaches the circulation space F6 and passes through the fire extinguishing filter 4. The flashback must pass through the fine holes of the fire-extinguishing filter 4, and at this time, the ignition heat is absorbed by the fire-extinguishing filter and the flashback is extinguished.

The reversing path R is formed so as to go in a direction opposite to the traveling direction of the flashback when entering the inflow port F8.
Since the flashback proceeds in a U-turn, the progress pressure of the flashback is greatly reduced here. Further, the traveling distance of flashback from the inlet F8 to the fire extinguishing filter 4 is longer than that of the conventional flashback preventing device. To extinguish the flashback.

When a flashback occurs, the lock valve mechanism 7 operates. That is, due to the ignition in the fuel gas supply passage, the pressure on the gas passage secondary side B becomes higher than the pressure on the primary side A, and the pressure relationship between the two is reversed. When the pressure in the flow space F5 increases, the flange 76 and the pressure operating member 70 of the second cylindrical body 32 operate by receiving this pressure, and the entire second cylindrical body 32 is moved to the gas flow passage secondary side. Move to A.

When the second cylindrical body 32 moves to the primary side A, the packing 71 comes into contact with the inner flange 21a of the first casing 21, and the space between the inflow port F1 and the flow hole F2 is shut off. When the second hollow 77b formed on the outer periphery of the second cylindrical body 32 matches the holding hole 72 of the lock ball 73 with the movement of the second cylindrical body 32, the first hollow 77a
The lock ball 73 moves to the second recess 77a by the inclination of the side surface and the bias of the spring 78.

Then, the reset cover 74 released from the restraint by the lock ball 73 moves to the gas flow passage secondary side B by the bias of the spring 78, and the inner surface thereof holds down the head of the lock ball 73 and fixes it. . Then, the lock ball 73 fitted into the second recess 77b is
Of the gas passage by the packing 71 is locked.

Further, by the movement of the reset cover 74,
Since the green status display band 79a is covered while the red status display band 79b is exposed, an operator who performs maintenance of the device can easily recognize that the lock valve mechanism 7 is in the operating state. When the reset cover 74 is manually pushed back to the gas flow path primary side A, the lock ball 73 enters the first recess 77a again to restrain the reset cover 74, and releases the fixing of the second cylindrical body 32. Then, the space between the inflow port F1 and the circulation hole F2 is opened.

As described above, according to the flashback prevention device 1 of the present embodiment, the reversal path R lowers the temperature at which flashback proceeds,
In order to reduce the traveling pressure, the fire can be surely extinguished. When an experiment was conducted on the flashback arrestor 1 of the present embodiment, it was confirmed that the maximum flashback blocking pressure was improved by about 0.5 kg / cm2 as compared with a conventional device having no reversing path R.

As described above, since the reversal path R bears the fire extinguishing ability of the flashback prevention device 1 and the size density of the passage holes of the fire extinguishing filter 4 can be increased to some extent, the fuel in the normal state While the gas flow characteristics can be improved, the fire extinguishing filter 4 can be small,
As in the present embodiment, a small flashback preventer 1 can be configured.

In addition, when a flashback occurs, the lock valve mechanism 7 in addition to the check valve 3 shuts off the fuel gas flow path in a double manner, so that the flashback prevention device 1 has a higher safety. A fire arrestor can be configured.

In this embodiment, the two inner cylinders 5 and 6 are used to form a one-stage reversing path R. However, a plurality of reversing paths are formed by incorporating more inner cylinders. You can also. Further, in the present embodiment, the inner cylinders 5 and 6 are fitted inside the fire extinguishing filter 4 to form the reversing path R inside the fire extinguishing filter 4, but the inner cylinder is arranged outside the fire extinguishing filter 4. , The reversing path may be formed on the outside thereof.

[0037]

As described in detail above, according to the flashback arrestor according to the present invention, according to the flashback arrestor described above, the reversal path greatly reduces the power of the flashback. The fire extinguishing performance of the vessel does not largely depend only on the fire extinguishing performance of the fire extinguishing filter. In other words, in anticipation of the share of the fire extinguishing performance, the flow rate performance of the fuel gas can be improved by increasing the opening density of the fire extinguishing filter. The size of itself can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional side view of a part of a flashback preventer according to an embodiment.

FIG. 2A is an explanatory diagram showing an operation state of a flashback arrestor when fuel gas flows backward, and FIG. 2B is an explanatory diagram showing an operation state of the flashback arrester when a flashback occurs.

[Explanation of symbols]

1 is a flashback preventer, 2 is a casing, 3 is a check valve, 4 is a fire extinguishing filter, 5 and 6 are inner cylinders, 7 is a lock valve mechanism, and R is a reversing path.

Claims (1)

(57) [Claims] 1. A check valve comprising: a check valve disposed on a primary side in a casing through which fuel gas passes; and a fire extinguishing filter on a secondary side, wherein a plurality of extinguishing filters are provided inside or outside the extinguishing filter. A plurality of spaces are formed between the casing, the fire extinguishing filter, and each of the inner cylinders by inserting the inner cylinder, and the plurality of spaces are connected in a longitudinal direction between the fire extinguishing filter and the fuel gas outlet of the casing. A flashback arrestor characterized by forming a reversing path for turning the direction of flashback.