JP2012215297A - Ignition prevention structure in installation handling combustible fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more enhance safety in an ignition prevention structure in an installation handling combustible fluid having a high risk of ignition under a high-temperature environment.SOLUTION: In this ignition prevention structure in the installation handling the combustible fluid, the outer surface of a high-temperature object 1 is covered with heat insulation material 2, and also the outer surface of the heat insulation material 2 is covered with a metal mesh 3. Further, the outer side of the metal mesh 3 is covered with an exterior member 4, and a purge gas supply pipe 12 for supplying purge gas is formed in a space inside of the exterior member 4.

Description

  The present invention relates to an ignition prevention structure applied to a facility that handles a flammable fluid that has a high risk of ignition under a high temperature environment.

When handling flammable fluids that have low ignition points, such as acetaldehyde and trichlorosilane, if they leak, they can lead to fire and major accidents, so it is necessary to take measures to prevent ignition.
In order to avoid ignition at the time of leakage of this kind of flammable fluid, it is necessary to secure a distance between the fluid and a high-temperature heat source. It is necessary to avoid or to prevent the spread of fire in the event of ignition.

  As a structure for preventing contact between a fluid and a high-temperature heat source, for example, there is a fireproof double-layer tube disclosed in Patent Document 1. In this fireproof two-layer pipe, a fireproof fiber-mixed mortar short pipe is inserted into the outer circumference of the pipe pipe, and a fireproof fabric, fireproof fiber in which a fireproof fiber material or adhesive is applied and impregnated on the outer circumference. The mesh is covered.

On the other hand, there is a flame arrester as an effective means for preventing the spread of fire in the event of ignition.
The flame arrester, for example, has a structure that allows combustion gas to pass through a narrow and long space formed of a wire mesh, etc., and the flame passes through this elongated space, so that the propagation speed is suppressed and the heat capacity of the wire mesh etc. It has the effect of heat dissipation, cooling, and extinguishing. In the flame arrester shown in Patent Document 2, a shell body containing a metal mesh is inserted in the middle of a pipe connecting a burner and a fuel mixer, and prevents the backflow of gas by the metal mesh and lowers the temperature of the backflow gas. Is presented.

JP 2009-236312 A JP-A-10-205719

By the way, trichlorosilane handled in a polycrystalline silicon manufacturing plant is a flammable fluid having a boiling point of 31 ° C., a flash point of −28 ° C., and an ignition point of 185 ° C. This trichlorosilane undergoes a combustion reaction in the presence of oxygen, and hydrogen is generated by hydrolysis in the presence of water. In either case, solid silica is generated. Hydrogen has low ignition energy and is easy to ignite.
In facilities that handle this type of flammable fluid, a safer ignition prevention measure is desired than the structure disclosed in the above patent document.

  The present invention has been made in view of such circumstances, and provides a structure with higher safety as an ignition prevention structure in a facility that handles a flammable fluid having a high risk of ignition under a high temperature environment. .

  The present invention is an ignition prevention structure for a facility that handles flammable fluid, and covers the outer surface of a high-temperature object with a heat insulating material, covers the outer surface of the heat insulating material with a metal mesh, and further covers the outside of the metal mesh. It is characterized by being covered with an exterior member.

Thus, by covering the outer surface of the high-temperature object with a heat insulating material and then covering it with the exterior member, it prevents direct contact between the flammable fluid and the high-temperature object and reduces the temperature of the outer surface of the exterior member. This prevents ignition when a flammable fluid is present in the vicinity. In addition, even when the fluid and a high-temperature object come into contact with each other through a gap between the exterior material and the heat insulating material, the flame propagates through the gap between the metal mesh covering the outer surface of the heat insulating material. It is not possible to prevent the spread of fire to the outside.
The high-temperature object is an object that reaches a temperature higher than the ignition point of a flammable fluid in various facilities such as reaction vessels, piping, tanks, and electrical equipment.

In the present invention, the mesh of the metal mesh is preferably formed in a gap smaller than 0.25 mm.
When the mesh opening of the metal mesh is a gap of 0.25 mm or less, a good fire spread prevention function can be exhibited even for hydrogen, which is a representative of flammable fluids through which flames most easily propagate.

  In the present invention, it is preferable to provide a purge gas supply pipe for supplying purge gas to the space inside the exterior member.

  By purging the inner space of the exterior member via the purge gas supply pipe, the pressure of the inner space of the exterior member can be made higher than the external pressure, and the intrusion of external fluid into the exterior member can be prevented. Thereby, the ignition of the fluid can be avoided. In addition, the purge gas flows through the mesh in the exterior member to prevent clogging of the mesh, and also prevents the mesh from spreading to flammable fluids such as trichlorosilane that accompany the generation of solids. It can be set as the state which maintained the function favorably.

According to the present invention, the surface temperature of the exterior member is lowered by the heat insulating material that covers the high-temperature object, and even if a flammable fluid comes into contact, ignition is suppressed. Thus, even when ignited by direct contact with a high-temperature object, heat is absorbed by the metal mesh covering the outer surface of the heat insulating material and flame propagation is prevented. Therefore, safety can be enhanced as an ignition prevention structure in a facility that handles a flammable fluid with a high risk of ignition under a high temperature environment.
In addition, by supplying purge gas while covering the outside of the metal mesh with an exterior member, it is possible to prevent the intrusion of fluid from the outside, and also prevent clogging of the metal mesh and maintain its soundness. It is possible to increase safety.

It is sectional drawing which shows one Embodiment of the ignition prevention structure of the facility which handles the fluid which has the combustibility of this invention. FIG. 2 is a front view showing the covering state of a heat insulating material or the like forming the ignition preventing structure of FIG.

Hereinafter, an embodiment of an ignition prevention structure for facilities handling flammable fluid according to the present invention will be described with reference to the drawings.
The ignition prevention structure of this embodiment is applied to a polycrystalline silicon manufacturing facility, and targets trichlorosilane, hydrogen, and the like as flammable fluids.
In FIG. 1, an ignition prevention structure in the vicinity of a joint portion of a pipe through which a high-temperature fluid flows is shown as a high-temperature object 1. In FIG. 2, a heat insulating material 2, a metal mesh 3, The covering structure of the exterior member 4 is shown.

  In the ignition preventing structure of this embodiment, the outer surface 1a of the high-temperature object 1 is covered with the heat insulating material 2, and the outer surface 2a of the heat insulating material 2 is further covered with the metal mesh 3, and further outside the metal mesh 3. Is covered with the exterior member 4.

  The high-temperature object 1 is a pipe through which a high-temperature fluid circulates in the illustrated example. However, the high-temperature object 1 is applied to an object that has a surface temperature of 500 ° C. or higher, for example, in various facilities such as a tank and an electric facility. In FIG. 1, a high-temperature object 1 is provided with a joint portion 7 formed by abutting a flange 6 via a seal member 5.

  As the heat insulating material 2, fiber materials such as glass wool and rock wool are preferably used, but various commonly used materials can be used. This heat insulating material 2 is formed in arc plate-like segments, and these are combined in the circumferential direction and the length direction of the high temperature object 1 to cover the entire outer peripheral surface of the high temperature object 1 as a pipe, The outer surface temperature of the heat insulating material 2 is kept below the minimum surface temperature (185 ° C.) at which trichlorosilane may be ignited. The heat insulating material 2 is also provided on both surfaces and the outer peripheral surface of the joint portion 7.

The metal mesh 3 is formed of a metal material having heat conductivity, is provided so as to be wound around the outer peripheral surface of the heat insulating material 2, and a plurality of the metal meshes 3 are provided along the length direction of the high temperature object 1 as a pipe. 1 covers the entire surface of the heat insulating material 2 outside. In this case, as shown in FIG. 2, both end portions of the metal mesh 3 wound around the heat insulating material 2 are overlapped, and each metal mesh 3 provided in the length direction is overlapped with each other. The gap is not formed between the metal meshes 3. The outer surface of the heat insulating material 2 provided around the joint portion 7 is also covered with the metal mesh 3. Moreover, it is better to provide a slight gap in order to effectively exhibit the function of the metal mesh 3 as a frame arrester without bringing the metal mesh 3 and the heat insulating material 2 into close contact with each other.
As the material of the metal mesh 3, various materials can be used as long as they do not burn, and the mesh opening 9 formed by the metal wires 8 of the metal mesh 3 is assumed to be hydrogen as described later. And 0.25 mm or less.

  The exterior member 4 is made of an appropriate material such as a metal plate, for example, and is provided so as to be wound around the outer peripheral surface of the metal mesh 3. A plurality of the exterior members 4 are provided along the length direction of the high-temperature object 1. It covers the entire outside. Similarly to the case of the metal mesh 3, the end portions of the exterior member 4 are overlapped so that no gap is generated between the exterior members 4. An exterior member 4 is also provided around the joint portion 7 so as to cover the metal mesh 3. Also in this case, it is better to provide a slight gap without bringing the metal mesh 3 and the exterior member 4 into close contact.

  A purge gas supply pipe 12 for supplying a purge gas to the inner space 11 surrounded by the outer member 4 is attached to the outer member 4, and the inner space 11 of the outer member 4 is maintained higher than the atmospheric pressure by the purge gas. As a result, the internal pressure always acts on the exterior member 4. As the purge gas, for example, various gases such as air, nitrogen gas, and carbon dioxide gas can be used.

  In the ignition prevention structure configured in this way, the outer surface 1a of the high-temperature object 1 is covered with the heat insulating material 2, so that the temperature of the outer surface is kept low, and there is a flammable fluid in the vicinity. Even in this case, ignition outside the heat insulating material 2 is prevented. Further, the outer surface 2a of the heat insulating material 2 is further covered with the metal mesh 3, and the outer side of the metal mesh 3 is covered with the exterior member 4, so that the high temperature object 1 is covered in triplicate and has combustibility. It is extremely unlikely that fluid will enter the inside through the gap between the exterior members 4, pass through the eyes of the metal mesh 3, and contact the high temperature object 1 via the gap in the heat insulating material 2. ing.

  Moreover, even if a flammable fluid enters through the gap between the exterior members 4 and ignites by contacting the high temperature object 1 through the gap between the metal mesh 3 and the heat insulating material 2, When the flame comes into contact with the metal mesh 3, heat is taken away by the metal wire 8 of the metal mesh 3, and the opening 9 of the metal mesh 3 is smaller than 0.25 mm. Propagation is suppressed and spreading to the outside is prevented.

By applying the ignition prevention structure as described above to various devices, piping, furnaces, etc. of polycrystalline silicon manufacturing facilities, flammable fluids such as chlorosilanes such as trichlorosilane and hydrogen approached the high-pressure object 1. Even in this case, it is possible to prevent ignition, and even in the event of ignition, it is possible to prevent the spread of fire.
In this case, in particular, hydrogen generated by hydrolysis of trichlorosilane has a high flame speed compared to other gases, easily propagates through small openings, and the concentration in air is from a minimum of 4% to a maximum of 75%. It is particularly difficult to suppress the flame caused by hydrogen. In the above-described embodiment, the maximum safety gap (the opening 9 of the metal wire 8) of the metal mesh 3 is formed to be smaller than 0.25 mm, so that the high temperature object 1 and the fluid are in direct contact with each other. Even if the fluid ignites, it is possible to reliably prevent the spread of fire by the metal mesh 3 in the gap.

Further, since the metal mesh 3 is covered with the exterior member 4 and the purge gas is supplied to the inner space 11 of the exterior member 4 via the purge gas supply pipe 12, the pressure of the inner space 11 of the exterior member 4 is changed to the pressure of the outer space. It is possible to prevent gas or the like from entering the exterior member 3 from the outside by increasing the pressure (atmospheric pressure). Further, when silica (SiO ₂ ) is generated by reaction of chlorosilanes with oxygen or water, it is easy to deposit as a solid matter, but since the purge gas flows from the inner space 11 of the exterior member 4 to the outside, the metal mesh 3 Due to the flow of the purge gas passing through the metal mesh 3, it is possible to prevent clogging due to silica or the like adhering to the metal mesh 3, and it is possible to always ensure the maximum safety gap and maintain the fire spread prevention function soundly. Furthermore, the purge gas lowers the surface temperature of the high-temperature object 1 and has an effect of preventing ignition or lowering the possibility of ignition when a flammable fluid comes into contact.

The ignition prevention structure of the present invention can be applied not only to the above-described polycrystalline silicon production equipment, but also to equipment for converting silicon tetrachloride to trichlorosilane, epitaxial equipment using trichlorosilane, etc., and ethylene gas or propane gas. It can be widely applied to chemical plants in general that handle flammable fluids such as the above and other flammable fluids.
It should be noted that the specific configuration of the present invention is not limited to this embodiment, and includes design changes and the like that do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 High temperature object 2 Heat insulating material 3 Metal mesh 4 Exterior member 5 Seal member 6 Flange 7 Joint part 8 Metal wire 9 Opening 11 Inner space 12 Purge gas supply pipe

Claims (3)

  An ignition prevention structure for a facility that handles flammable fluid. The outer surface of a high-temperature object is covered with a heat insulating material, the outer surface of the heat insulating material is covered with a metal mesh, and the outer side of the metal mesh is further covered with an exterior member. An ignition prevention structure characterized by that. 2. The ignition preventing structure according to claim 1, wherein the opening of the metal mesh is formed in a gap smaller than 0.25 mm.   The ignition prevention structure according to claim 1, wherein a purge gas supply pipe for supplying a purge gas is provided in a space inside the exterior member.

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