KR101777301B1 - Emission system of carbon dioxide fire extinguishing system in nuclear power plants equipped with Electric heater for prevention of dry ice generation - Google Patents

Abstract

The present invention relates to a carbon dioxide fire extinguisher discharging carbon dioxide when a fire occurs in a nuclear power plant. More specifically, the present invention introduces a carbon dioxide discharge system of the nuclear power plant having an electric heater for preventing dry ice generation which is able to secure fire extinguishing performance of the fire extinguisher by preventing a concentration of discharged carbon dioxide from being fallen below a minimum fire extinguishing concentration by preventing the dry ice generation generated in a discharge head in which the carbon dioxide is discharged when the fire occurs the inside of a fire protection area of the nuclear power plant. Also, the present invention prevents the dry ice generation by sublimating dry ice particles generated near the discharge head when the fire actually occurs, and thus, the discharged carbon dioxide concentration satisfies a designed concentration within a certain time, so the fire extinguishing performance of the fire extinguisher can be secured. The carbon dioxide discharge system comprises: a plurality of discharge heads installed inside the fire prevention area; the electric heater connected with the discharge head by a pipe, installed inside a storage tank storing the carbon dioxide and inside the fire prevention area, and installed to be located in a lower part of the discharge head; and a control part receiving a fire generating signal from a fire detector when the fire occurs inside the fire prevention area, and controlling the storage tank and the electric heater.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon dioxide emission system for a nuclear power plant having an electric heater for preventing dry ice formation,

The present invention relates to a carbon dioxide fire extinguishing system that emits carbon dioxide when a fire occurs in a nuclear power plant. More specifically, the present invention relates to a carbon dioxide fire extinguishing system that prevents carbon dioxide from being generated in a fire- The present invention relates to a carbon dioxide emission system for a nuclear power plant equipped with an electric heater for preventing generation of dry ice that can prevent the concentration of carbon dioxide from being lowered to a minimum level of digestion and thereby ensure the extinguishing performance of the digester.

Generally, the water-based fire-extinguishing system suppresses the fire by spraying fire-extinguishing agents such as water or foam when a fire occurs. In this case, expensive equipment or facilities are lost, and fire extinguishing gas is sprayed in places where water- Evolved gas-based fire-fighting equipment will be used.

Where gas-based fire extinguishing equipment that emits fire extinguishing gas as described above is mainly used, there are places where electrical facilities such as an electric room, a substation room, a power generation room and a storage room are concentrated, a document storage room where water can not be recovered, , Computer rooms, communication facilities, museums that store or display valuable cultural assets and treasures, places where flammable liquids or dangerous materials are stored, and national infrastructure such as nuclear power plants. .

The type of gas used in the gas system fire extinguishing system is that a high pressure vessel storing the extinguishing gas such as carbon dioxide, halon, nitrogen, and argon (Ar) is installed inside or outside the protection zone, The high-pressure vessel is automatically opened to evolve fire in a protected area (hereinafter referred to as "fire protection zone").

In addition, the fire protection zone in which the gas-based fire extinguishing equipment is installed is provided with an air flow blocking means such as a fire shutter or an automatic closing device for blocking the inflow of outside air during a fire, do.

In addition, the air consists of about 21% oxygen, 78% nitrogen and 1% other materials, oxygen in the air promotes combustion (oxidation) and the extinguishing gas is in a high pressure or liquid state As the fire extinguishing gas stored in the high-pressure vessel is sprayed, the ambient temperature is lowered and the oxygen concentration in the air is reduced to about 15% or less to suppress the fire.

That is, the gas system fire extinguishing system stores the fire extinguishing agent in the container, and when the fire occurs, the fire extinguishing agent is injected into the fire area and the fire is suppressed by the sucking and cooling action. , The amount of the chemical, the overpressure, etc. are not managed, the fire suppression performance is never guaranteed.

On the other hand, fire extinguishing facilities using carbon dioxide are most widely used in nuclear power plants where gas fire extinguishing facilities are installed, and the carbon dioxide is released into the fire zone to reduce the oxygen concentration to below the standard value to suppress the fire.

The carbon dioxide fire extinguishing system can be divided into a high pressure gas system fire extinguishing system and a low pressure gas system fire extinguishing system. The high pressure gas system fire extinguishing system stores carbon dioxide in a plurality of storage containers, And the low-pressure gas-based fire extinguishing system is a system in which a large amount of carbon dioxide is stored in the storage tank, and the on-off valve is opened for a predetermined time according to the designed concentration when a fire occurs.

As shown in FIG. 1, a plurality of discharge heads 110 'are installed in a fire protection zone 100', for example, in a conventional high pressure carbon dioxide fire extinguishing system, , The discharge head 110 'is connected to the storage container 120' installed outside the fire protection area 100 'by piping and is connected to the fire detector 130' when a fire occurs inside the fire protection area 100 ' When the fire signal is transmitted to the control unit 140 ', the control unit 140' controls the storage container 120 'to supply the carbon dioxide stored in the storage container 120' through the discharge head 110 ' '), The fire is extinguished.

In connection with the above, in Korea, since there is no provision for the emission test at the nuclear power plant's carbon dioxide fire extinguishing facility, the release test is not conducted and the release test is applied by applying the US Fire Protection Standard (NFPA 12) However, as a result of the field emission test, it was confirmed that fire extinguishing facilities do not meet the performance standards due to lack of CO2 emission or concentration in various fire protection areas.

In addition, the reason that the extinguishing gas is discharged below the design concentration, that is, the concentration after the extinguishing agent (extinguishing gas) is discharged is firstly as follows. First, in the case of the extinguishing system using carbon dioxide as the extinguishing gas, At the same time, carbon dioxide equivalent to about 46% of the amount of fire extinguishing agent is generated as dry ice by suddenly cooling in the atmosphere by the effect of the line-Thomson, and the concentration of fire extinguishing gas inside the fire- Secondly, all gas system fire extinguishing facilities do not satisfy the design concentration. However, as the design error or the degree of confidentiality is degraded, the predicted amount of fire extinguishing agent is estimated by considering the enclosure integrity of the protected area This is a typical cause of leaking of fire extinguishing gas.

In particular, the cause of the generation of dry ice in the vicinity of the discharge head where carbon dioxide is emitted has a great influence on the fire suppression performance in an actual fire situation.

Korean Patent No. 1178148 Korea Patent Publication No. 2013-0006479 Korea Patent Publication No. 2013-0133604

DISCLOSURE Technical Problem The present invention has been made to solve the above problems of the related art. In the conventional carbon dioxide extinguishing system, dry ice is generated in the vicinity of a discharge head where carbon dioxide is emitted when a fire occurs, A solution to this problem is to use carbon dioxide of a nuclear power plant equipped with an electric heater for preventing dry ice generation that activates the electric heater before the emission of carbon dioxide through the emission head to sublimate the fine dry ice particles generated in the emission head, The present invention has been made to solve the above-mentioned problems.

In order to achieve the above-mentioned object, the present invention provides a fire-fighting apparatus comprising: a plurality of discharge heads installed in a fire protection zone; a discharge tank connected to the discharge head by a pipe, And a control unit for receiving a fire generation signal from the fire detector when a fire occurs and controlling the storage tank and the electric heater inside the fire protection zone. Carbon dioxide of nuclear power plant equipped with electric heater We propose an emission system.

Further, the electric heater of the present invention is characterized in that a nichrome wire is installed inside a protection pipe made of inconel, and is formed horizontally with the ground, and is formed in a zigzag shape.

According to another aspect of the present invention, there is provided an ejection head including a connection portion connected to a pipe, a body coupled to a lower portion of the connection portion, and having a plurality of ejection openings formed on a side thereof, the body being embedded in the ejection opening, And a heating coil embedded in the heating coil so as to be positioned above and below the heating coil.

As described above, in the nuclear power plant equipped with the electric heater for preventing the formation of dry ice according to the present invention, The emission system can prevent the generation of dry ice by sublimating the dry ice particles generated near the emission head in the event of an actual fire situation, so that the concentration of the emitted carbon dioxide can satisfy the designed concentration within a predetermined time, The effect can be obtained.

1 is a schematic view showing a conventional high pressure carbon dioxide fire extinguishing system of a nuclear power plant;
2 is a schematic view of a low-pressure carbon dioxide extinguishing system according to a preferred embodiment of the present invention.
3 is a perspective view illustrating a heater of a low-pressure carbon dioxide extinguishing system according to a preferred embodiment of the present invention.
4 is a side view of a discharge head and a heater of a low pressure carbon dioxide extinguishing system according to a preferred embodiment of the present invention.
5 is a cross-sectional view of a discharge head portion side of a low-pressure carbon dioxide extinguishing system according to a preferred embodiment of the present invention.
6 is a side view of a discharge head, a heater, and a heater of a low pressure carbon dioxide extinguishing system according to a preferred embodiment of the present invention.
7 is a bottom view of a discharge head and a heater unit of a low-pressure carbon dioxide extinguishing system according to a preferred embodiment of the present invention.

More particularly, the present invention relates to a carbon dioxide fire extinguishing system for discharging carbon dioxide during a fire in a gas fire extinguishing system, and more particularly, to a fire extinguishing system for a nuclear power plant using a carbon dioxide fire extinguishing system, There is provided a dry ice prevention electric heater capable of ensuring the extinguishing performance of the fire extinguishing system by preventing the generation of dry ice near the discharge head 10 in which the concentration of carbon dioxide is released, Carbon dioxide in a nuclear power plant ≪ / RTI >

Nuclear power plants using CO2 fire extinguishing facilities were found to be incapable of satisfying the performance criterion as a result of field emission test.

The reason why the carbon dioxide fire extinguishing system does not satisfy the performance criteria is as follows. First, in the case of the fire extinguishing system using carbon dioxide as the extinguishing gas, the carbon dioxide is discharged from the discharge head where the carbon dioxide is released. At the same time, Carbon dioxide equivalent to about 46% of the amount of fire extinguishing agent is generated as dry ice, so that the concentration of fire extinguishing gas in the fire protection area does not satisfy the design concentration within a certain time, secondly, The fire extinguishing system is designed to estimate the amount of fire extinguishing agent considering the enclosure integrity of the protected area during design, but the leakage of the fire extinguishing gas is unpredictable as the design error or air tightness is impaired. Typically, At the same time as it is released from the head, carbon dioxide is generated as dry ice, The digestion performance of the fire-fighting equipment is influenced by the cause of the gas concentration does not meet the design concentration within a predetermined time.

On the other hand, carbon dioxide can be easily liquefied by cooling and compression, and may be changed into solid-state dry ice through cooling and expansion.

In relation to dry ice production, Thomas J. Wysocki points out in the Fire Protection handbook that the rate of dry ice production is related to the temperature at which carbon dioxide is stored, and the low and high pressure carbon dioxide dry ice production rates are about 45% and 25% of the total.

When gas and liquid coexist, pressure is correlated with temperature. When pressure and temperature increase, gas increases density, but liquid decreases density. Between 56.6 ° C and a critical temperature of 31 ° C, CO ₂ in the vessel is present as gas or liquid, and at the critical point, the density of the gas equals the density of the liquid so that there is no clear distinction between the two phases. exist. When the temperature is reduced to 56.6 ° C at the critical point (31 ° C, 75.2kg / m2), CO2 reaches the triple point where gas, liquid, and solid coexist in equilibrium with each other. Only below the triple point, only gas and solid have.

In the case of the low-pressure carbon dioxide extinguishing system, when CO ₂ in the liquid phase is released to the atmospheric state, it is partially vaporized immediately to become vapor, while the remaining portion is deprived of the vaporization heat by the evaporation. As a result, about 55% Is evaporated and the remaining 45% becomes dry ice, which is in the form of finely chopped eyes.

In addition, the carbon dioxide extinguishing system can be divided into a high-pressure gas-based fire-extinguishing system and a low-pressure gas-based fire-extinguishing system. In the high-pressure gas-based extinguishing system, carbon dioxide is stored in a plurality of storage vessels, In the low-pressure type gas-based fire extinguishing system, a large amount of carbon dioxide is stored in the storage tank, and the on-off valve is opened for a predetermined time according to the designed concentration when the fire occurs.

Compared with the low-pressure carbon dioxide extinguishing system, the carbon dioxide particle size of the low-pressure carbon dioxide extinguishing system is several hundred microns, while the high-pressure type is smaller than that of the low-pressure carbon dioxide extinguishing system. Compared to carbon dioxide fire extinguishing equipment, the low pressure carbon dioxide extinguishing equipment takes a relatively long time to sublimate because of differences in dry ice production.

In the case of low-pressure carbon dioxide extinguishing equipment, about 46% of dry ice is converted to dry ice in the case of discharging. In this case, the heat of sublimation of carbon dioxide, which is a direct solid gas, , The effect is only about 1/8 of that of the same amount of water released, and the cooling effect on the hot surface, but its efficiency is lowered.

For this reason, even if the same amount of carbon dioxide is emitted, the concentration of the low-pressure carbon dioxide extinguishing system is lower than that of the high-pressure carbon dioxide extinguishing system, and the extinguishing effect is also reduced accordingly. In the present invention, This will be described as an embodiment.

In order to accomplish the above-mentioned object, the present invention is characterized in that it comprises a plurality of discharge heads 10 installed in a fire protection zone 100, a storage tank 20 connected to the discharge head 10 by piping and storing carbon dioxide An electric heater 30 installed inside the fire protection zone 100 and positioned below the emission head 10; And a control unit 50 receiving a fire occurrence signal from the fire detector 40 in the event of a fire in the fire protection zone 100 and controlling the storage tank 20 and the electric heater 30. [ .

In addition, the electric heater of the present invention is characterized in that a nichrome wire 34 is installed inside a protective pipe 32 made of inconel, and is formed horizontally with the ground, and is formed in a zigzag shape.

The discharge head 10 of the present invention includes a connection portion 11 connected to a pipe, a body 13 coupled to a lower portion of the connection portion 11 and having a plurality of injection ports 12 formed at a side thereof, And a heating coil 14 embedded in the body 13 so as to be positioned above and below the jetting port 12, do.

Hereinafter, the present invention will be described in detail with reference to FIGS. 2 to 7 showing embodiments of the present invention.

When a fire is generated in the fire protection zone 100 and a fire is detected by the fire detector 40, the fire detector 40 sends a fire signal to the control unit 50 The control unit 50 receiving the fire signal transmits the emission signal to the storage tank 20 and the storage tank 20 receiving the emission signal corresponds to the volume of the fire protection zone 100 The discharged carbon dioxide is moved along the piping and discharged into the fire protection area 100 through the discharge head 10. The carbon dioxide is discharged through the discharge head 10 to the inside of the fire protection area 100, At this time, it is obvious that the controller 50 seals the fire protection zone 100 after receiving the fire signal, and informs the occurrence of the fire by activating the siren and the warning light.

At this time, the discharge head 10, which is a main component for achieving the present invention,

A plurality of fire extinguishers are installed in the fire protection area 100 so that the carbon dioxide moved through the pipes can be injected downward in the lower direction so that carbon dioxide is uniformly distributed throughout the fire protection area 100 So as to be sprayed.

In addition, the discharge head 10 of the present invention generally has a radial type, which is used for an electric heat discharge system installed near the upper center of the inside of the fire protection zone 100, that is, near the ceiling center if there is a ceiling, And is emitted through the injection port 12 of the emission head 10 by the emission of carbon dioxide when a fire occurs. As described above, the carbon dioxide (CO2) passing through the injection port 12 Is suddenly cooled in the atmosphere by the Row-Thomson effect, and dry ice is produced.

Specifically, the discharge head 10 includes a connection portion 11 connected to a pipe installed in the fire protection zone 100, and a plurality of injection holes 12 formed on a side surface of the connection portion 11 And a body (13) which is made of a synthetic resin.

The body 13 may further include a heating coil 14 embedded in the inside of the body 13 so as to be positioned above and below the ejection opening 12, 14 can be operated alone upon release of carbon dioxide or can be operated together with the electric heater 30 to be described later to realize the effect of preventing generation of dry ice.

That is, the heating coil 14 raises the temperature of the lower portion and the upper portion of the body 13 of the discharge head 10 where the injection port 12 is formed, when carbon dioxide is discharged from the discharge head 10, The generation of dry ice can be prevented.

The storage tank 20, which is a main component for achieving the present invention,

(Not shown) connected to the discharge head 10 installed inside the fire protection zone 100 and storing carbon dioxide therein. When the fire is generated, the control unit 50, which will be described later, So that the carbon dioxide for reaching the designed concentration is released into the pipe.

The electric heater 30, which is a main component for achieving the present invention,

The structure is installed in the ceiling of the structure or the ceiling provided in the upper part of the interior of the fire protection zone 100 so as to be positioned below the emission head 10, And is heated and heated by the control unit 50, which will be described later, before the carbon dioxide is discharged through the discharge head 10, whereby the dry ice particles generated are sublimated.

That is, the electric heater 30 of the present invention is heated before the carbon dioxide is discharged through the discharge head 10 to sublimate the dry ice particles generated near the discharge head 10, so that the concentration of carbon dioxide emitted for a predetermined time is designed Thereby achieving the effect of enabling the concentration to be reached.

In this case, the electric heater 30 of the present invention is characterized in that a nichrome wire 34 is installed inside a protection pipe 32 made of inconel material. The nichrome wire 34 is protected by the protective pipe 32 made of inconel material It is possible to minimize the damage caused by the high-pressure carbon dioxide discharged through the discharge head 10.

The electric heater 30 of the present invention is formed horizontally with the ground and is formed in a zigzag shape. The electric heater 30 is formed at a right angle to the direction in which carbon dioxide is emitted through the emission head 10, that is, It is possible to obtain an effect of efficiently sublimating particles of the generated dry ice.

Further, since the electric heater 30 of the present invention is formed in a zigzag shape, it is possible to obtain an effect that the generated dry ice particles can be more effectively sublimated by increasing the contact area without interfering with the emission of carbon dioxide.

In addition, the electric heater 30 of the present invention can be formed in the form of a mesh in addition to a zigzag shape. If the electric heater 30 is formed in the form of a net, the strength can be improved and the damage caused by the carbon dioxide released can be further minimized. Can be maximized.

In addition, the electric heater 30 of the present invention uses an emergency power source rather than a commercial power source for the operation, and is operated as an emergency power source in the event of a fire by the control unit 50 to be described later.

The heating coil 14 and the heater unit 60 to be described later are also preferably installed to receive power for operation like the electric heater 30 of the present invention. 30, and the heater unit 60 are all connected to different power sources, if possible, in order to prevent power from being cut off together.

The control unit 50, which is a main component for achieving the present invention,

A fire alarm signal is received from the fire detector 40 when a fire occurs in the fire protection zone 100 and a fire alarm signal is transmitted from the fire detector 40 to the storage tank 20 and the electric heater 30, It is desirable to simultaneously operate the storage tank 20 and the electric heater 30 so that the electric heater 30 can be sufficiently preheated before the carbon dioxide is discharged from the discharge head 10. [

That is, the control unit 50 of the present invention receives a fire occurrence signal from the fire detector 40 in the event of a fire, controls the storage tank 20, activates the siren and the warning light, The concentration of carbon dioxide emitted by sublimation of fine dry ice particles generated when carbon dioxide is discharged from the discharge head 10 can reach the designed concentration by operating the electric heater 30 before being discharged from the discharge head 10 .

The heater unit 60, which is a main component for achieving the present invention,

And is installed inside the fire protection area 100 so as to be positioned around the emission head 10 so that when the ceiling is formed inside the fire protection area 100, that is, around the emission head 10, And when the ceiling is not formed, it is installed in a structure in which the piping or the discharge head 10 is installed and emits infrared rays toward the discharge head 10 when carbon dioxide is discharged from the discharge head 10 Thereby realizing the effect of preventing the generation of dry ice around the discharge head 10. [

That is, the principle of the heater unit 60 of the present invention is that the infrared rays emitted from the discharge head 10 are emitted from the discharge head 10 to a strong pressure The temperature of the periphery of the discharge head 10 can be raised, and the effect of preventing the generation of dry ice can be obtained.

7, the heater unit 60 includes a circular rail 62 installed inside the fire protection zone 100 and having a discharge head 10 installed at the center thereof, And a steering member (64) installed on the circular rail (62) and irradiating infrared light to the center.

In addition, the steering member 64 is provided at the center of a heat source (not shown) for generating heat, so that the radiant heat generated from the heat source can be transferred to the discharge head 10 And is installed on the circular rail 62 so as to protrude downward, and is moved along the circular rail 62 when a fire is generated.

That is, the steering member 64 is moved along the circular rail 62 in the event of a fire to raise the ambient temperature of the discharge head 10 so that dry ice is formed around the discharge head 10 due to the carbon dioxide discharge .

The fire signal is transmitted to the control unit 50 by the fire detector 40 when a fire occurs in the fire protection zone 100 and the storage tank 20 ) And the electric heater 30 are operated so that the electric heater 30 is preheated before the carbon dioxide is discharged into the fire protection zone 100 through the discharge head 10 and the dry ice particles generated in the vicinity of the discharge head 10 So that the concentration of carbon dioxide emitted can reach a designed concentration capable of suppressing the fire, thereby improving the performance and reliability of the carbon dioxide fire extinguishing system.

In addition to the electric heater 30, the present invention also includes a heating coil 14 embedded in the discharge head 10 and a heater 60 moving circularly around the discharge head 10 and radiating radiant heat By suppressing the generation of carbon dioxide more effectively, the concentration of carbon dioxide emitted in the event of a fire can reach the designed concentration, thereby ensuring the performance of the carbon dioxide extinguishing facility.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It is possible to carry out various changes in the present invention.

100: Fire protection area
10: Discharge head 12:
13: Body 14: Heating coil
20: storage tank 30: electric heater
32: Protector 34: Nichrome wire
40: fire detector 50:
60: heater part 62: circular rail
64: Steering member

Claims (4)

A plurality of discharge heads 10 installed in the fire protection zone 100;
A storage tank 20 connected to the discharge head 10 by piping and storing carbon dioxide;
An electric heater 30 installed inside the fire protection zone 100 and positioned below the emission head 10 and heated before the carbon dioxide is discharged through the emission head 10;
A control unit 50 for receiving a fire occurrence signal from the fire detector 40 when a fire occurs in the fire protection zone 100 and controlling the storage tank 20 and the electric heater 30; And
A circular rail 62 installed inside the fire protection zone 100 and positioned so that the emission head 10 is positioned at the center of the circular rail 62; And a heater unit (60) having a heater (64)
The electric heater (30)
A nichrome wire 34 is installed inside the protective pipe 32 made of inconel, is formed horizontally with the ground, is formed in a zigzag shape,
The discharge head (10)
A connection part 11 connected to the pipe;
And a heating coil 14 coupled to a lower portion of the connection portion 11 and having a plurality of injection holes 12 formed on a side surface thereof and embedded in the upper and lower portions of the injection hole 12, (13), characterized in that the heat exchanger Emission system.
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