JPS63220884A - Fire extinguishing equipment of exhaust duct - 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 (Field of Industrial Application) This invention relates to fire extinguishing equipment for fires in exhaust ducts, for example, equipment such as semiconductor manufacturing equipment, or equipment for extinguishing exhaust ducts in rooms where such equipment is installed. This provides fire extinguishing equipment suitable for extinguishing fires.

(Prior art) In rooms where semiconductor manufacturing equipment is installed, so-called clean rooms, dust and dirt generated near the equipment,
The exhaust gases used in the manufacturing process are sucked in through the main ducts that communicate with the bases of these ducts using individual ducts that open toward the respective equipment, and are then removed from the main duct using an exhaust fan. An exhaust duct is used which discharges this exhaust air from the exhaust end of the exhaust gas into, for example, the outside atmosphere.

The working gases used above are highly flammable (and can cause a fire in the exhaust duct together with dust, etc., causing great damage to equipment, etc., so extinguishing the exhaust duct is extremely important. Conventional exhaust duct fire extinguishing equipment has a plurality of gas discharge nozzles arranged at appropriate intervals in the main duct, and a valve such as a fuse damper at the tip of the duct that opens toward the equipment. and a damper at the discharge end, and in the event of a fire alarm, the valves and damper are closed and a fire extinguishing gas such as COt gas is discharged from the gas discharge nozzle at a sufficiently high pressure.

(Problems to be Solved by the Invention) In the conventional fire extinguishing equipment described above, the valves at the tips of the branch ducts and the dampers at the discharge end of the main duct are both closed, that is, the exhaust duct is sealed. Since extinguishing gas is discharged from the gas discharge nozzle into this exhaust duct, there are the following problems, as will be explained later in the experimental results.

(al) Due to the residual air, working gas, etc. trapped in the exhaust duct, the rate of increase in the concentration of the extinguishing gas in the duct is suppressed, and the time required to reach the predetermined concentration required for extinguishing the fire becomes longer.

In particular, it is completely impossible to reach a concentration of approximately 100%, which would ensure reliable extinguishing of various flammable working gases.

(bl) In order to push a predetermined amount of fire extinguishing gas into a closed exhaust duct as quickly as possible, it is necessary to release the fire extinguishing gas in a short time.

Problem (a) above becomes a fatal drawback in that it makes initial extinguishing of a fire inside the exhaust duct extremely difficult. , the duct may be damaged.

By the way, it is unclear at what point in the exhaust duct, which is long and thin with a small cross-sectional area, where a fire will occur, and it is also possible that the fire will occur deep inside the duct, where the mist has accumulated inside the duct. be. In order to prevent the spread of a fire within the exhaust duct and to reliably extinguish the fire, it is necessary to fill the entire exhaust duct with a fire extinguishing gas atmosphere of a concentration higher than that required for extinguishing the fire in a short period of time. Furthermore, it is also necessary to maintain the gas concentration for longer than the time required to extinguish the fire.

However, in conventional equipment, fire extinguishing gas is emitted from multiple gas discharge nozzles distributed in a long sealed exhaust duct, which causes the above-mentioned problems and Residual air, etc. does not mix evenly with the released fire extinguishing gas, resulting in areas in the duct where the concentration of extinguishing gas is higher than the concentration required for extinguishing the fire and areas where it is thinner than the concentration required for extinguishing the fire. If the concentration of extinguishing gas in the area where the fire is occurring is low, there is a problem in that the fire cannot be extinguished and the fire will spread.

(Means for Solving the Problems) This invention solves the above-mentioned problem that appears in conventional fire extinguishing equipment, in that it takes a long time for the extinguishing gas concentration to reach a predetermined level, and the extinguishing action is insufficient. Moreover, it fundamentally solves the problem of the duct being easily damaged due to the sudden increase in pressure inside the duct due to the release of extinguishing gas, and it can be used to reduce the
This paper proposes a fire extinguishing equipment for an exhaust duct that can reach a concentration close to 10% and that does not cause damage to the duct due to the release of fire extinguishing gas. A plurality of branch ducts 11 are collectively connected to the main duct 1 on the base side, and are connected to the room or equipment 1 by an exhaust fan 3 provided at the discharge end 2 of the main duct 1
In an exhaust duct configured to discharge exhaust gas such as 3 to the outside air or to an after-treatment device, a gas discharge nozzle 10 is installed in the main duct 1 between the discharge end 2 and the duct 11 closest to this discharge end. At the same time, a branch duct 11 in which the gas discharge nozzle 10 is connected to a fire extinguishing gas supply source, and the supply amount of fire extinguishing gas supplied from the fire extinguishing gas supply source into the duct via the gas discharge nozzle 10 is controlled by an open branch duct 11. All of the fire extinguishing ducts are equipped with a flow rate control means for controlling the flow rate to a level necessary to generate a piston effect by the fire extinguishing duct, and the exhaust end is equipped with a flow rate control means to prevent the extinguishing gas from leaking to the outside air or to the after-treatment device. This is a fire extinguishing equipment for an exhaust duct, which is characterized by being equipped with a means to prevent leakage.

(Function) The exhaust duct has the discharge end 2 of the main duct 1 and the branch duct closest to this discharge end 2 inside it, with the tip 12 which is the exhaust suction port of the branch duct 11 remaining open. Since the fire extinguishing gas is discharged from the gas discharge nozzle 10 provided between the gas discharge nozzle 10 and the gas discharge nozzle 11, the pressure within the duct hardly increases during discharge, and the gas is discharged smoothly.

The fire extinguishing gas released into the exhaust duct 11 is transferred to the air inside the duct or to the work gas duct 11 in an open state.
This extrusion action causes the air in the exhaust duct to be discharged from the tip 5 to the outside of the exhaust duct, and the inside of the exhaust duct is quickly replaced with extinguishing gas, which is necessary for extinguishing a fire. It reaches a high concentration of almost 100%.

These fill the exhaust duct with highly concentrated extinguishing gas in a very short time.

In addition, in the branch duct 11 in the open state, the fire extinguishing gas flows out from the tip 12 due to its specific gravity, and as a result of this outflow, the fire extinguishing gas in the main duct is transferred into the fire duct 11. A suction piston effect occurs, which prevents outside air from flowing into the duct 11.
The concentration of fire extinguishing gas in the exhaust duct is maintained at a high concentration.

(Example) Next, an example of the present invention will be described along with various experimental results.

(1) Regarding closing or opening of the tip of the technical duct,
Regarding the release of extinguishing gas with the tip of the branch pipe open, which is one of the features of the configuration of this invention, the rising state of the gas concentration, etc. were investigated.

The simulated exhaust duct shown in perspective in Figure 2 is a main duct MA with 4m long technical ducts l+ and lit arranged approximately horizontally.
And a 4m long branch duct I! 3,1. The main duct MA has a damper d at its discharge end a, and a valve V at the tip of each of the ducts lI to 14.
~v4 is provided, and the height difference between the main duct MA and the main duct M is 1 m.

The gas discharge nozzles n1 to 1. discharge CO2 gas as an example of fire extinguishing gas G into the main ducts M, , M,.

(a) Case of conventional fire extinguishing equipment FIG. 3 shows the experimental results of a conventional exhaust duct fire extinguishing equipment using nozzles n, to n4.

In Fig. 3 (a), both valves V and ~v4 and damper d are closed, so this corresponds to the conventional fire extinguishing equipment described above, and nozzles n1xn4 emit CO2 larger than the reduct volume. However, the gas concentration in the exhaust duct is
It rises very slowly and only rises to about 80%. Additionally, as Cot was released, the pressure inside the duct reached a maximum of 201 mAq. It took about 4 minutes and 30 seconds to reach about 80% concentration, demonstrating the shortcomings of conventional fire extinguishing equipment in which extinguishing gas is forced into a sealed exhaust duct. It can be said that

In the conventional device, since air remains in the exhaust duct, the increase in gas concentration is suppressed, so each technique duct z+ ~
The experiment was conducted by fully opening the valves ① and .about.v4 at the tips of No. 14 to allow the air in the exhaust duct to flow out from the valves v1 to v4.

As shown in FIG. 3 (0), the gas concentration reached only 60% at maximum, contrary to expectations.

Further, in some of the branch ducts β2, an outside air suction phenomenon occurred in which outside air was sucked into the duct through the valve v2 at the tip. It should be noted that almost no increase in the pressure inside the duct due to the release of CO2 was observed.

For this reason, an experiment was conducted in which the supply amount of CO□ was approximately doubled and the valves V and -v4 of each of the ducts 1 to 14 were kept half open. The results are as shown in FIG. 3(c), and the gas concentration at each part was not significantly different from that of the conventional device in FIG. 3(a). This is the main duct MA.

A plurality of nozzles n,”−n4 to C
The air inside the duct is released to release O2.
It is presumed that this is because it is agitated by O2 and remains inside the duct without being discharged outside the duct.

(b) Release of extinguishing gas from the discharge end side From the above experiments, the conventional device and the method of extending the conventional device,
It has been found that it is extremely difficult to increase the concentration of fire extinguishing gas in the exhaust duct to nearly 100% in a short period of time.

For this reason, CO8 is released only from the nozzle n provided between the exhaust end al of the exhaust duct and the first trick duct lI, and at the same time, CO8 is released only from the nozzle n provided between the exhaust end al of the exhaust duct and the first trick duct lI. When the valves v1 to v4 at the tips of 1 to It4 were fully opened, the gas concentration rose quickly in a short period of time, as shown in Figure 4 (A). In this case, an outside air suction phenomenon occurs.

On the other hand, in the case of Fig. 4 (II) where the valves v2 to v4 of the technical duct lz-β4 are open and only the valve V of the technical duct 11 is closed, the pressure inside the duct decreases to approximately Omm at q. The gas concentration rises in the far red, and in the opened branch duct 1z-14, the time required to reach about 80% concentration is about 18 seconds to 48 seconds.

For the branch pipe X whose tip is closed, it takes about 2 minutes, and as a result of this, the air inside the duct with the tip of the exhaust duct open is transferred to the exhaust end a.
It has been found that the extinguishing gas can be effectively pushed out by the extinguishing gas discharged from the gas discharge nozzle n provided at the side.

From this experiment, we opened the tip of the branch duct and
A gas discharge nozzle is installed between the discharge end of the main duct and the duct closest to this discharge end, and if fire extinguishing gas is supplied into the duct from this nozzle, the air in the exhaust duct can be quickly pushed out to the outside air. It was found that it was possible to create a highly concentrated fire extinguishing gas atmosphere of almost 100% in a short period of time.

(CJ technique duct opening area and fire extinguishing gas discharge flow rate from the horizontal main duct N to multiple branch ducts) The size and opening state of the tip of the branch duct h were investigated.

The model duct shown in perspective in Figure 5 releases CO and gas from one end of the main duct N, which is closed at both ends.
The flow in the exhaust duct was investigated by the flow of white smoke released from the exhaust duct.

As shown in FIG. 6, the branch duct h.

~ In the case of an exhaust duct in which all the tips of h4 are fully opened, the discharge flow rate of COz gas as fire extinguishing gas is small (
Figure 6 (a)) or inside! ((U) in the same figure), outside air suction phenomenon occurs in some of the gi ducts, but if the discharge flow rate is increased, CO2 gas is sucked out of the outside air from all gi ducts as shown in Figure 6 (c). The outside air suction phenomenon does not occur.

Figure 6 (d) with all branches h+ to h4 half open
and some branch ducts h5. In FIG. 6 (N) with h2 closed, no outside air suction phenomenon occurs even if the discharge flow rate is set to a medium amount.

The results of this experiment revealed that in order to prevent the suction of outside air from occurring in the technical ducts, there is a correlation between the discharge flow rate of fire extinguishing gas and the total opening area of the branch ducts.

(2) Regarding the height of branch ducts, volume of exhaust ducts, etc. The height of branch ducts, the cross-sectional area of main ducts, and the size of exhaust ducts are determined by the size of the clean room in which it will be used. Check whether the outside air suction phenomenon occurs or not.
This was investigated in relation to the amount of gas released.

Note that a non-directional nozzle was used as the gas discharge nozzle, and the gas discharge flow rate was controlled by changing the nozzle diameter of the gas discharge nozzle.

The results are illustrated in FIG.

(Regarding the rising height of the al-technical duct, Fig. 9 (a) shows data regarding the standard duct model's standard duct height 400 cranes, which is shown in a front view in a front view, and Height 1465n+
When compared with Figure 8 (N), which is the data of the main duct) N
It can be seen that when the discharge end a of the branch duct h is closed, it is necessary to increase the gas discharge flow rate in accordance with the height of the branch duct h in order to prevent the occurrence of the outside air suction phenomenon by the branch duct h.

(b) Regarding the diameter of the main duct, the diameter of the main duct N is 50 mm in Figure 8 (b) and 50 mm.
When compared with Fig. 8 (c), which is 0 a+, the branch duct h
The size of the diameter of the main duct N is irrelevant to whether or not an outside air suction phenomenon occurs.

(C) Exhaust duct volume Comparing the reference duct model (Figure 9 (a)) in which the volume of the exhaust duct is 41 and Figure 8 (Ill) in which the volume is 14.2 f, the outside air suction phenomenon of the branch duct h is found. The size of the exhaust duct volume is irrelevant to whether or not it occurs.

(d) Regarding external pressure, the external pressure at the location where the tip of branch duct h faces is Q + nAq
In the case of the reference duct model, whose external pressure is 4 mAq
Comparing the exhaust duct (not shown in Figure 8) that is held at the same position and discharged, if the exhaust end a of the main duct N is closed, the magnitude of the external pressure is It is irrelevant whether or not the outside air suction phenomenon occurs.

When the discharge end a is open, the gas discharge flow rate is increased according to the external pressure at the location where the tip of the duct h faces, thereby preventing the outside air suction phenomenon of the duct h. can.

As a result of the experiments shown in Figures 4 to 8, in an exhaust duct that has multiple exhaust suction ducts, the concentration of extinguishing gas in the duct can be reduced to approximately 10'0, which has a very high extinguishing effect in a short time. %, a gas discharge nozzle is installed between the discharge end of the exhaust duct and the duct closest to this discharge end to discharge extinguishing gas. It has been found that it is better to leave the technique duct open.

Furthermore, it has been found that there is a gas release flow rate that prevents the suction of outside air from occurring in the plurality of open branch ducts when extinguishing gas is released.

The discharge flow rate of fire extinguishing gas that does not cause this outside air suction phenomenon has almost no relation to the volume of the exhaust duct, which was previously thought, but rather depends on the opening area and rising height of the duct, as well as the location where the branch duct faces. It has become clear that it is highly dependent on the external pressure.

By the way, in the experiment shown in Figure 8, CO from the avocational duct was
At the time when the external outflow in step 2 started, in the branch duct where the CO2 outflow started last, CO□ falls through the branch duct at a speed similar to natural falling due to the difference in specific gravity with the outside air and flows out to the outside. However, it was also found that this falling CO□ caused a so-called piston effect in the duct to suck in the CO□ in the main duct, thereby preventing the phenomenon of suction of outside air. Therefore, if the extinguishing gas is supplied through the duct at a flow rate that causes this piston effect to occur continuously, a high concentration can be maintained in the exhaust duct with minimal consumption of the extinguishing gas.

Furthermore, from the experimental results shown in Figure 8, "the minimum discharge flow rate Qkg/mi at which no suction phenomenon occurs in the exhaust duct"
n is Q=cArcozv/11go'C; Correction coefficient Tcoz; Fire extinguishing gas density kg/m 3A; Cross-sectional area (total) of the technical duct m2 H; Approximate formula for the rising height of the branch duct m was obtained. .

(3) About the opening area (total) of branch ducts
In order to eliminate the phenomenon of suction of outside air from the exhaust duct, extinguishing gas must be discharged from the gas discharge nozzles n, to n1° at a flow rate corresponding to the opening area (total) of the branch ducts t in the exhaust duct.

The presence or absence of a suction phenomenon for the full-scale exhaust duct shown in perspective in Figure 9 was determined by the opening area (total) and discharge flow rate (total).
Figure 10 shows the results of the investigation in relation to the above, and it can be seen that there is a linear proportional relationship.

As a result, the experimental results of the simulated duct were reproduced in the full-scale duct.

The discharge flow rate of the fire extinguishing gas was adjusted by changing the discharge diameter of the gas discharge nozzle in the same manner as described above.

゛ Note that the discharge flow rate of the fire extinguishing gas may be adjusted by providing a flow rate control valve in the fire extinguishing gas supply source instead of adjusting the diameter of the gas discharge nozzle.

(a) Regarding the opening of the discharge end of the main duct - a An open/close type damper is provided at the discharge end of the main duct, and the damper is closed when a fire is detected, but it is not possible to always obtain a complete seal. Not limited.

Therefore, if there is a leak at the discharge end of the main duct, an additional amount of gas corresponding to the leakage amount may be discharged from the gas discharge nozzle.

By installing a leak prevention means such as a valve or an airtight damper at the exhaust end of the exhaust duct that can sufficiently prevent fire extinguishing gas from leaking into the outside air or after-treatment equipment, outside air can be removed from the outside air in the exhaust duct. This makes it possible to further reduce the minimum flow rate at which no suction phenomenon occurs, which helps to reduce the amount of extinguishing gas used.

(About the leakage prevention means provided at the exhaust end of the exhaust duct (a) As a leakage prevention means, the exhaust fan opens depending on the outside air such as air in the exhaust duct or the exhaust flow to the aftertreatment device, and the gas is released from the gas release nozzle. A valve such as a damper may be used, which has the function of not opening depending on the amount of extinguishing gas used, but preventing air from flowing into the exhaust duct from the outside air or the after-treatment device.

(0) Also, as a leakage prevention means, as shown in FIG. Main duct 1
A command is output to cause the electromagnetic solenoid 5 to close the valve 4 in conjunction with the fire detection operation of the fire detector 6 installed at the This is carried out by a control section 9 composed of something like a microcomputer.

This prevents the extinguishing gas from flowing out from the discharge end 2, and the extinguishing gas discharged into the main duct l-1.
The air in the main duct 1 and the technical duct 11 is pushed out, and the technical duct 11 is made to flow and flows into the equipment 13 from the tip 12.

Note that the control unit 9 may be configured to close the valve 4 when a fire is detected when a predetermined time has elapsed from the opening operation of the extinguishing gas discharge valve 8.

According to this configuration, the air near the discharge end 2 of the main duct 1 can be discharged to the outside, and the vicinity of the discharge section 2 can also be filled with fire extinguishing gas.

(Effects of the Invention) As described above, the exhaust duct fire extinguishing equipment according to the present invention includes a gas discharge nozzle 10 provided between the discharge end 2 of the main duct 1 and the technical duct 11 closest to this end 2. Duct 11
Since the extinguishing gas is discharged from the gas discharge nozzle 10 into the interior of the gas discharge nozzle 10 while the tip 12 of the duct remains open, there is almost no pressure rise within the duct during discharge, and the gas is discharged smoothly. .

The extinguishing gas released into the exhaust duct 11 quickly pushes out the air or working gas in the duct toward the tip 12 of the open duct 11, and this pushing action causes the air in the exhaust duct to The extinguishing gas is discharged to the outside from the section 12, and the inside of the exhaust duct is replaced in a short time by the extinguishing gas, resulting in a high concentration that is extremely effective in extinguishing fire.

In addition, in the technical duct 11 into which a high concentration of extinguishing gas has flowed, the extinguishing gas flows down due to its specific gravity and flows out from the tip 12, and as a result of this outflow, the extinguishing gas in the main duct 1 is A piston effect occurs that sucks the gas into the duct 11, and this causes the outside air to flow into the duct 1-.
11, and the concentration of fire extinguishing gas in the exhaust duct is maintained at a high concentration, resulting in an excellent fire extinguishing effect.

In addition, a gas discharge nozzle 1 is installed near the exhaust end 2 of the exhaust duct.
0 or a nozzle 10 and leakage prevention means, construction is simple and can be easily installed in an existing exhaust duct.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention; FIG. 1 is an overall front view, FIG. 2 is a perspective view of an experimental example, FIGS. 3 and 4 are data for the two experimental examples shown in FIG. 2, and FIG. Figure 6 shows the second
Figures 7 and 8 are front views and data in the third experimental example, Figure 9 is a perspective view in the fourth experimental example, and Figure 10 is data in the fourth experimental example. be. ■ Main duct, 2 Discharge end, 3 Exhaust fan, 10 Gas discharge nozzle, 11 Technical duct, 12 Tip, 13 Equipment

Claims (8)

[Claims] (1) A plurality of branch ducts opening into a room or equipment are collectively connected to the main duct at the base side, and an exhaust fan installed at the exhaust end of the main duct exhausts the room or equipment. In an exhaust duct that discharges to the outside air or after-treatment equipment, a gas discharge nozzle is provided in the main duct between the discharge end and the branch duct closest to this discharge end, and the gas discharge nozzle is connected to a fire extinguishing gas. The amount of extinguishing gas connected to the supply source and supplied from the extinguishing gas supply source into the duct through the gas discharge nozzle is such that a piston effect by the extinguishing gas is generated in all of the open branch ducts. Exhaust duct fire extinguishing equipment, characterized in that it is equipped with a flow rate control means that controls the flow rate to a level higher than that required for the exhaust duct. (2) The fire extinguishing equipment for an exhaust duct according to claim 1, wherein the flow rate control means is the diameter of the gas discharge nozzle. (3) The fire extinguishing equipment for an exhaust duct according to claim 1, wherein the flow rate control means is a valve device provided in a fire extinguishing gas supply source. (4) A plurality of branch ducts opening into a room or equipment are collectively connected to the main duct at the base side, and exhaust air from the room or equipment is carried out by an exhaust fan installed at the exhaust end of the main duct. In fire extinguishing equipment for exhaust ducts that discharge to the outside air or after-treatment equipment, a gas discharge nozzle is installed in the main duct between the discharge end and the branch duct closest to this discharge end; It is connected to a fire extinguishing gas supply source, and the supply amount of fire extinguishing gas supplied from the fire extinguishing gas supply source into the duct through the gas discharge nozzle is controlled by the piston effect of the fire extinguishing gas in all open branch ducts. A flow rate control means is provided to control the flow rate to the required flow rate to generate the gas, and a leak prevention means is provided at the discharge end to prevent the extinguishing gas discharged from the gas discharge nozzle into the exhaust duct from leaking into the outside air or the aftertreatment device. Exhaust duct fire extinguishing equipment characterized by being provided with. (5) The exhaust duct according to claim 4, wherein the leakage prevention means is constituted by a valve that closes the discharge end in conjunction with the discharge operation of fire extinguishing gas from the gas discharge nozzle. fire extinguishing equipment. (6) The exhaust duct fire extinguishing equipment according to claim 4, wherein the flow rate control means is the diameter of the gas discharge nozzle. (7) The fire extinguishing equipment for an exhaust duct according to claim 4, wherein the flow rate control means is a valve device provided in the fire extinguishing gas supply source. (8) Extinguishing the exhaust duct according to claim 5, characterized in that the leakage prevention means is configured such that the closing operation of the valve is delayed by a predetermined time from the start of the discharge of extinguishing gas. Facility.