WO2007020727A1 - Method for cutting in closed working space for handling harmful substance - Google Patents

Abstract

[PROBLEMS] To improve a working environment for cutting a member, to be cut, containing a harmful substance in a closed space by thermal cutting, which is relatively easily in work, and thus to ensure safety for workers. [MEANS FOR SOLVING PROBLEMS] A member to be cut is flame-cut with a flame torch (16) within a close working house. The construction of the flame torch (16) is such that a preheating flame (52) of a hydrogen gas, a propane gas, or an oxygen gas, which increases the susceptibility of the member to burn, is produced around the outer peripheral part, and an oxygen gas is blown out to the center part to produce a cutting oxygen gas stream (53). Cutting is carried out by heating the member (4) to be cut to the ignition temperature with the preheating flame (52), spraying an oxygen gas against that part to burn the member (4), melting the member (4) by the heat, and, at the same time, blowing off limewash and slag produced by the combustion by blowing force of the cutting oxygen gas stream (53). In this state, the flame torch (16) is moved in a direction indicated by an arrow to successively remove the member (4) by the preheating flame (52) and the cutting oxygen gas stream (53) and thus to cut the member (4) into a groove shape.

Description

 Specification

 Cutting method in a closed work space that handles hazardous substances

 Technical field

 [0001] The present invention cuts a member that contains or contains a harmful substance to the human body, so that the harmful substance is not scattered to the outside. The present invention relates to a cutting method that enables cutting in a sealed work space. Background art

 [0002] In facilities that handle radioactive substances that are harmful to the human body, persistent organic pollutants (for example, dioxin, PCB, etc.), or substances that cause serious diseases such as carcinogenesis (for example, aspect), When disassembling, repairing, and disassembling facility equipment, it becomes necessary to cut the parts that contain or contain the harmful substances, and the work for cutting prevents the harmful substances from being scattered outside. For this reason, it was conducted in a special case isolated from the surroundings.

 [0003] As a cutting method, in consideration of the compatibility at the work site, the simplicity of the equipment used, the cutting speed, etc., rather than the mechanical cutting method using a bite cutter, circular saw, etc., gas cutting, Thermal cutting methods such as laser cutting and laser cutting are used. However, since plasma cutting and laser cutting require special equipment and operation, gas using propane gas or acetylene gas is generally used. Cutting is used universally for cutting work! Speak.

 FIG. 12 is a plan view showing a schematic configuration of the work site of the conventional gas cutting method (using propane gas and acetylene gas), and FIG. 13 is a cross-sectional view taken along line BB in FIG.

 In FIG. 12 and FIG. 13, 1 is a work house as a sealed work space in which the external force is shut off in a sealed state, and 2 is for a worker to thermally cut the workpiece 4 with a flame torch 3. Cutting work table, 5 temporary storage area for cut objects, 6 handling area for heavy objects, 7 front room with double room structure for workers to enter and exit, 8 for loading heavy objects, Z outlet, 9 for waste Drum for storage, 10 is a cooling unit, 11 is a local exhaust dust collection unit.

[0006] In addition, 12 is an exhaust filter installed outside the house and connected to the local exhaust dust collection unit 11 via a duct 13. A wind exhaust unit, 14 is oxygen and propane gas used for cutting Alternatively, an oxygen / combustible gas storage place where acetylene gas is installed, and 15 is a gas supply pipe for supplying cutting gas to the flame torch 3.

[0007] Gas cutting using propane gas or acetylene gas as described above is a force commonly used as cutting work, the amount of fumes generated during cutting, the temperature rise around the work, the high temperature of the member to be cut There are a number of issues that are problematic in terms of thermal protection measures for workers.

 [0008] The use of plasma cutting and laser cutting in special cutting environments such as reactor demolition is described in Patent Documents 1 to 3, etc., but as described above, general plasma cutting and laser cutting are described. Cutting requires special equipment and operation.

 [0009] In particular, plasma cutting uses a plasma at a temperature of 10,000 to 20,000 ° C, where the cutting speed is faster than gas cutting, and the cutting target range is wide. The amount of fumes generated during cutting, Thermal protection measures for workers, such as a rise in the temperature around the work and an increase in the temperature of the parts to be cut, become a problem.

 [0010] On the other hand, workers who work in a sealed work space are required to wear protective equipment to protect themselves from harmful substances, and to provide thermal protection, flame retardant clothing is required. It is also necessary to take flame-proofing measures such as wearing.

 Conventionally, in order to improve such a working environment, ventilation in a sealed working space has been improved, or the frequency of replacement of workers has been increased and has been powerful.

 Patent Document 1: Japanese Patent Laid-Open No. 10-206588

 Patent Document 2: Japanese Patent Laid-Open No. 2001-166090

 Patent Document 3: Japanese Unexamined Patent Publication No. 2002-1543

 Disclosure of the invention

 Problems to be solved by the invention

[0012] However, the thermal cutting work performed in the sealed work space is aerated for the operator! On the other hand, the hot air stays in the sealed work space as a general work place. It becomes force and high temperature. In addition, there are many cases where sufficient space cannot be obtained as a closed space for work, and when working in a narrow space, there are cut objects that have become hot due to cutting, so the radiant heat from them is also close to the operator. Will join. In addition, a number of workers including flameproof clothing Since heavy protective equipment is installed, the thermal load on the workers is large.

 [0013] In Japan, the legal regulation of working environment temperature is not limited to underground work, but according to the high temperature tolerance standard in the US ACG IH (American Industrial Hygiene Experts Council), The standard clothing correction factor must be taken into account, and when working in an enclosed space, the WBGT (Heat Heat Index) must be kept lower (30 ° C or less, 25 A temperature of about ° C is considered good).

 [0014] However, in the current situation of the cutting site in the above-mentioned environment of the sealed work space, the force that may be 40 ° C ~ 50 ° C far exceeding 30 ° C The current situation is that it has not been completed.

 [0015] For this reason, by developing a thermal cutting method that generates less heat, it is possible to control the temperature rise of the work environment in the sealed work space, to increase the temperature of the object to be cut, and to reduce the radiant heat, thereby causing burns, etc. In addition, the development of a thermal cutting method that eliminates the risk of fume generation, and there has been a need to reduce the risk of worker contamination exposure due to harmful substances contained in the fume.

 [0016] Therefore, the present invention solves the above-described problems of the prior art and provides a working environment for cutting a member to be cut having a toxic substance in a sealed working space by thermal cutting that is relatively easy to work. The purpose is to provide a cutting method in a closed work space that can improve the safety of workers.

 Means for solving the problem

[0017] In order to achieve the above object, the present invention cuts a member to which a harmful substance adheres or contains, so that the harmful substance does not scatter to the outside! A cutting method for cutting to a predetermined size, wherein a cutting target member is installed in the sealed space, and a flame torch having a gas outlet diameter selected in accordance with the thickness of the cutting target member in the sealed space Is installed opposite to the cutting site, hydrogen gas and supporting oxygen gas are ejected from a part of the flame torch to ignite and preheat the cutting site with the generated flame, and other parts of the flame torch. Oxygen gas is ejected to generate a cutting oxygen stream, and the cutting site is cut by cutting combustion using the cutting oxygen stream. According to the thermal cutting method using hydrogen gas by this method, for example, propane Using gas Heat Compared with the cutting method, environmental degradation factors such as radiant heat, temperature rise, and carbon dioxide generation amount can be reduced, and generation of fumes and dusts is reduced, and the effect of preventing the scattering of harmful substances is increased. Since it is possible to safely cut the material to be cut that contains harmful substances in the space, the working environment in the sealed work space is significantly improved compared to the conventional case, and the risk of burns and the like of workers is eliminated. In addition, the risk of worker exposure to harmful substances and the risk of spreading contamination can be reduced.

 [0018] In the cutting method in the closed work space for handling the harmful substances, the gas jet diameter of the flame torch which ejects the gas quantity that provides the amount of gas combustion heat required for cutting with respect to the maximum wall thickness of the member to be cut. Can be selected. As a result, even if the material to be cut changes in thickness, it is easy to cut without changing work tools and procedures such as replacing the flame torch during work. It becomes possible.

 [0019] Further, in the cutting method in the closed work space for handling the harmful substances, the gas cutting state in the target member is adjusted by adjusting the moving speed of the flame torch according to the specifications such as the thickness and material of the target member to be cut. Can be made uniform. This makes it possible to align the cut surface and cutting state at the cutting site of the member to be cut, and facilitate processing and processing after cutting.

 [0020] Further, in the cutting method in the sealed work space for handling the harmful substances, the carbon-containing gas can be mixed into the hydrogen gas. This makes it possible to make the combustion of hydrogen gas visible by adding a small amount of carbon-containing gas, such as propane gas, as necessary, and it is safe for workers to perform work with a flame torch. Improves.

 [0021] Further, in the cutting method in the closed work space for handling the harmful substances, the mixing ratio of the carbon-containing gas to the hydrogen gas can be 50% or less, preferably 20% or less. The mixing ratio of the carbon-containing gas is preferably 20% or less from the economical and working environment, but within this mixing range, it is possible to maintain the combustion state (combustion speed) mainly composed of hydrogen gas.

 The invention's effect

[0022] According to the present invention, a hydrogen combustion flame is used as a preheating flame for cutting. Compared with the thermal cutting method using mouth pan gas, it can reduce environmental degradation factors such as radiant heat, temperature rise, and carbon dioxide generation amount, and it has less fume and dust generation and prevents harmful substances from scattering. Therefore, it is possible to safely perform the work of cutting the target material having harmful substances in the sealed work space, and the work environment in the closed work space is significantly improved compared to the conventional work environment. The risk of burns and other hazards can be eliminated, and the risk of worker exposure to contamination and the risk of spreading contamination can be reduced. is there.

 BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

 FIG. 1 is a plan view showing a schematic configuration of a work site for explaining Embodiment 1 of a cutting method according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. Note that members corresponding to those described in FIGS. 12 and 13 are denoted by the same reference numerals.

 In FIG. 1 and FIG. 2, reference numeral 1 denotes a work space as a sealed space in which an external force is shut off in a sealed state, and a mouse 2 denotes a member to be cut 4 with a flame torch 16 described later. Cutting work table for thermal cutting, 5 is a temporary storage area for cut objects, 6 is a heavy goods handling area, 7 is a front chamber of a double-chamber structure where workers enter and exit, and 8 is a heavy goods carry-in Z A carry-out port, 9 is a drum can for storing waste, and 11 is a local exhaust dust collection unit.

 [0026] In addition, 12 is an exhaust filter that is installed outside the house and connected to the local exhaust dust collection unit 11 via a duct 13, and an exhauster unit 14 is installed with a cylinder such as oxygen gas and propane gas. Oxygen and combustible gas storage area, 15 is a gas supply pipe for supplying the necessary gas to the flame torch 16, and 17 is a hydrogen Z oxygen electrolyzer for generating cutting gas used for cutting work.

[0027] In this embodiment, as will be described in detail later, the heat load in the work house 1 is reduced, the amount of fumes is reduced, and the hydrogen Z oxygen electrolyzer 17 is installed. Since the number of installed oxygen cylinders can be reduced, the number of installed parts such as cooling unit 10, local exhaust dust collection unit 11, exhaust filter 'exhaust unit 12 and oxygen' combustible gas storage 14 is reduced. Space saving compared to the conventional example shown in FIGS. be able to.

 FIG. 3 is a schematic configuration diagram of a water electrolysis-type hydrogen-oxygen separation generator as an example of the hydrogen-Z oxygen electrolysis apparatus in the present embodiment, 21 is a hydrogen gas separation tank, 22 is an oxygen gas separation tank, 23 Is an electrolytic cell that causes electrolysis of water in both tanks 21 and 22, 24 is a power supply that supplies power to the electrolytic cell 17, 25 is a water replenishing tank that supplies water to both tanks 21 and 22, and 26 is Electrolyte cooling system that cools the electrolyte solution in both tanks 21 and 22 within the set temperature range, 27 is the circulation pump for the electrolyte solution cooling system 26, 28 cools the hydrogen gas and oxygen gas generated in both tanks 21 and 22 The gas cooling system 29 is a gas path for sending hydrogen gas and oxygen gas to the outside. In the gas path 29, a pressure gauge 30, a backfire prevention device 31 and the like are provided.

 [0029] In the water electrolysis-type hydrogen-oxygen separation generator having the above-described configuration, in both tanks 21, 22 in which water and the electrolyte are mixed, electrolysis is caused by the electrolytic bath 23 to separate hydrogen gas and oxygen gas. To generate.

 In the first embodiment, cutting combustion gas is supplied from the hydrogen Z oxygen electrolysis device 17 to one (or more) flame torch 16 via the gas outflow control device. In this example, as a preheating gas for cutting, hydrogen gas is the main component, and mainly for the purpose of coloring to improve the visibility of the combustion flame, carbon-containing gas as an additive gas (In this example, propane gas) is mixed, and a mixed gas containing combustion supporting oxygen gas for combustion support is used.

 FIG. 4 is a block diagram showing the configuration of the gas outflow control device in this embodiment. The gas outflow control device 36 includes a hydrogen Z oxygen electrolysis device 17 that generates hydrogen and oxygen, and propane. A gas storage tank 37 is provided.

[0032] In FIG. 4, a gas flow is provided from the flow rate of the hydrogen gas supplied to the hydrogen gas supply pipe 38 connected to the hydrogen gas separation tank 21 of the hydrogen Z oxygen electrolyzer 17 shown in FIG. A gas flow rate detector 39 for detecting the amount of incoming gas, a gas flow rate adjusting device 41 for controlling the flow rate of the supplied propane gas, provided in the gas supply pipe 40 connected to the propane gas storage tank 37, and a gas Control unit 42 that controls the flow rate of propane gas by operating the flow rate regulator 41 in response to the detection data of the hydrogen gas flow rate detected by the flow rate detector 39 And a mixed Z supply unit 43 for supplying the mixed gas of hydrogen gas and propane gas to the flame torch 16 as a preheating gas.

Further, in FIG. 4, 31 and 31 are check valves, 44 is an operation input unit for an operator to input setting data, 45 is a memory unit provided in the control unit 42, 46 and 46 are The pressure regulator, 47 is an oxygen cylinder.

 FIG. 5 is a cross-sectional view for explaining a crater portion and a cut state of the flame torch in the present embodiment, showing a configuration example of a premix type crater portion, In Fig. 16, 50 is a preheating gas passage through which preheating gas (mainly hydrogen gas + propane gas + combustion oxygen gas) ignited as a preheating flame, 51 is an oxygen gas passage through which oxygen gas ejected as a cutting oxygen stream passes. It is.

 [0035] As the crater portion, in addition to the premixed crater portion, an out-mixed type can be used, and the crater portion is not limited to the one shown in FIG.

 Next, the cutting operation and the operation of each component of the first embodiment having the above-described configuration will be described.

 [0037] In the first embodiment, when a device or material contaminated with a harmful substance such as a radioactive substance is to be discarded, as shown in Fig. 1, these are stored in a waste storage drum 9. Work to cut equipment and materials contaminated with the above-mentioned hazardous substances so that they can be processed and are suitable for storage, transportation and post-processing.

 [0038] The worker who performs the above-mentioned work wears protective equipment necessary for the work, enters the house front room 7 which is the entrance / exit of the work house 1, and protects the work only in the work house 1 such as flameproof clothing. After installing the tools, enter the work house 1. The house front room 7 has a double-chamber structure, which prevents the diffusion of harmful substances to the outside of the work house 1 by entering the rooms in order.

[0039] The member to be cut 4 is carried in from the heavy goods loading Z carry-out port 8, and first, in the work house 1, after unpacking the member 4 to be cut and cured for transportation, a cutting work table 2 sets are set. The set member to be cut 4 is heat cut using a flame torch 16 as will be described later, so that it can be stored in the waste storage drum 9. Then, cooling is performed until the temperature of the cut member reaches a temperature at which the waste storage drum can 9 can be stored. With the temperature of the cut member lowered, the member is stored in the work house 1 as a waste storage drum. Put in 9. When a predetermined amount of cutting member is stored in the waste storage drum 9, the waste storage drum 9 is sealed with a lid, and is transported from the work house 1 through the heavy material loading Z unloading port 8.

 [0040] In the cutting operation, in FIG. 4, the worker has data on an appropriate mixing ratio of hydrogen gas and propane gas, which is a preheating gas necessary for the cutting processing to be performed, and cutting oxygen gas supply amount. Data, that is, set value data (described later) set in advance based on a demonstration test or the like is input from the operation input unit 44 to the control unit 42.

 [0041] Further, as the gas outlet diameter of the crater portion in the flame torch 16, a gas outlet diameter capable of ejecting a gas amount capable of obtaining the amount of gas combustion heat required for cutting with respect to the maximum thickness of the member 4 to be cut is selected. By doing so, even if the material to be cut 4 changes in thickness, it can be easily cut without changing work tools and procedures such as replacing the flame torch 16 during the work. Is possible.

 [0042] Further, the moving speed of the flame torch 16 may be adjusted according to the specifications of the thickness and material of the member 4 to be cut, so that the gas cutting state in the member 4 to be cut is made uniform. . As a result, the cut surface and cutting state at the cutting site of the member 4 to be cut can be made uniform, and processing and processing after cutting can be facilitated.

 [0043] The cutting operation is performed in consideration of the above-mentioned various points. In FIG. 4, the input set value data is stored in the control unit 42 which also has an electric control circuit power such as a CPU (central processing unit). The hydrogen gas that is stored in the memory unit 45 and received by the control unit 42 by receiving the detection data of the hydrogen gas flow rate detected by the gas flow rate detector 39 and reading the mixed set value data from the memory unit 45. Control the outflow regulator 41, which also has power, such as a gas flow control valve, so that the mixing ratio of propane gas to the gas is always constant. Similarly, the oxygen gas supply amount is controlled.

In this way, the mixed gas of hydrogen gas and propane gas, which is the preheating gas supplied to the flame torch 16, is always supplied to the mixed Z supply unit 43 while being regulated to a predetermined mixing set value. Furthermore, in the flame torch 16, oxygen gas generated in the hydrogen Z oxygen electrolysis unit 17 or oxygen / combustible gas that supplies oxygen when the oxygen gas from the hydrogen Z oxygen electrolysis unit 17 is insufficient. Blow flame is generated by receiving oxygen gas from 47 oxygen cylinder 47 Thus, the member 4 to be cut is cut.

 In the flame torch 16, as shown in FIG. 5, a preheating flame 52 is generated at the outer peripheral portion of the flame torch 16, and oxygen gas is jetted at the central portion to generate a cut oxygen stream 53. For cutting, the member to be cut 4 is heated to the ignition temperature (about 900 ° C for steel) with the preheating flame 52, and oxygen gas is blown onto that part to burn the member 4 to be cut. At the same time that 4 is melted, the product and the melted product (noro, slag) produced by combustion are blown off by the jet power that the cutting oxygen stream 53 has. In this state, by moving the flame torch 16 in the direction of the arrow, the member 4 to be cut is sequentially removed by the preheating flame 52 and the cutting oxygen air flow 53, and the member 4 to be cut is cut into a groove shape.

 [0046] In the present embodiment, the data of the proper mixing ratio with the propane gas mixed in the hydrogen gas (mixing set value data) was verified based on a demonstration test and the result shown in Fig. 6 was obtained. .

 [0047] As shown in FIG. 6, when the hydrogen concentration is up to 80%, the force that is the combustion speed of the gas mainly composed of hydrogen gas, if less than this, the effect of using the hydrogen gas as in this embodiment will be reduced. However, in order to maintain the combustion state (combustion speed) mainly composed of hydrogen gas, the effect of the invention and the economy are sufficient if the mixing ratio of propane gas to hydrogen gas is 50% or less. It is preferable that it is 20% or less in terms of workability and work environment.

 [0048] Further, oxygen gas is used as the hydrogen combustion gas. In this case, the oxygen gas generated in the hydrogen Z oxygen electrolysis device 17 can be used, and the hydrogen Z oxygen electrolysis device is used. 17, the hydrogen gas and oxygen gas generated can be effectively used.

 [0049] By adopting the thermal cutting method using hydrogen gas as the fuel for the preheating flame as in this embodiment, the radiant heat and temperature are compared with the conventional thermal cutting method using mainly propane gas. As well as being able to reduce environmental degradation factors such as rising and carbon dioxide generation, and as a result of less generation of slag, fume and dust, it is shown that It was possible to confirm by such a demonstration test.

 [0050], Test method

Inside a 2 X 2 X 2 (internal capacity 8m3) sealed house surrounded by polyethylene sheet (without ventilation), longitudinal direction of test piece (SN490B, size 500mm X 100mm X thickness 22mm) 500m A cutting test was conducted using m as a preheating gas, hydrogen gas (with a small amount of propane gas added) and propane gas.

[0051] In the cutting test, the time required for cutting, the amount of dust in the sealed house at the end, the temperature, and the gas concentration were measured. Gas concentration measuring device: Kitagawa type detector tube manufactured by Komyo Rigaku Kogyo Co., Ltd., Dust amount measuring device: Digital dust meter manufactured by Shibata Kagaku Co., Ltd., Hydrogen generator: Water electrolysis type hydrogen oxygen separation generator manufactured by ILT Technology.

[0052] The measurement results of the cutting test are shown in (Table 1).

[0053] [Table 1]

前記試験片を長さ 50cm切断した結果、切断前に比べて、密閉ハウス内の気温は、 水素ガス切断では 21. 5°Cから 7°C上昇して、 28. 5°Cになったのに対して、プロパン ガス切断では 21. 5°Cから 20. 4°C上昇して、 41. 9°Cになり、温度上昇量は、プロパ ンガス切断に対して水素ガス切断では 66%減少した。

As a result of cutting the test piece 50 cm in length, the temperature inside the sealed house increased from 21.5 ° C to 7 ° C to 28.5 ° C in the hydrogen gas cutting compared to before cutting. In contrast, propane gas cutting increased by 20.4 ° C from 21.5 ° C to 41.9 ° C, and the amount of temperature increase was 66% lower than hydrogen gas cutting compared to propan gas cutting. .

[0054] In addition, the carbon gas concentration was 870 ppm for hydrogen gas cutting, which showed almost no increase, but for propane gas cutting, it was over 4000 ppm (the maximum concentration over the detector tube used).

 [0055] The dust concentration was 5.2 mgZcm3 in hydrogen gas cutting, which was about 1 Z2 or less in the case of propane gas cutting. The increase in dust concentration was reduced by 58% for hydrogen gas cutting compared to propane gas cutting.

 In addition, oxygen consumption was 21 LZmin for propane gas cutting, while it was 5.7 LZmin for hydrogen gas cutting, a 73% decrease.

[0056] The amount of fumes generated was reduced by 50% for propane gas cutting, compared with 72 ± 34 mgZmin for hydrogen gas cutting, and 36 mg for 32 mgZmin. [0057] From the result of this cutting test, according to the hydrogen gas cutting method of the present embodiment, the cutting operation of the member to be cut having harmful substances in the sealed space, which is the subject of the present invention, It has a great anti-scattering effect and can safely perform cutting work on members to be cut that contain harmful substances in a sealed space, and the working environment is greatly improved compared to other conventional thermal cutting methods. It can be seen that the practical effects are significant, such as eliminating the danger of burns to workers, and reducing the risk of worker exposure to contamination and the spread of contamination by harmful substances.

 [0058] Below, we will further verify and confirm the individual items shown in (Table 1) for the factors that affect the work environment, and compare and examine the differences between hydrogen gas cutting and propane gas cutting.

 [0059] Consider the amount of heat that generates a comparison of the thermal effects on the work environment and the environmental impact from the movement mode (radiation, convection, heat transfer, etc.).

 [0060] When the influence of the preheating flame is verified, among the preheating flames, the propane gas flame emits light and emits about 50% of the energy generated by combustion due to black body radiation. Because it does not emit light, it does not emit black body and emits about 10% of the combustion heat and does not release power (see (Table 2)).

 [0061] [Table 2]

Next, when verifying the heat balance at the time of cutting, cutting is performed by melting the steel with the combustion heat generated by the oxygen of the member to be cut (steel), generating an oxide, lowering the melting point, and improving the fluidity. It is done by making it good. The hydrogen gas that forms the preheating flame functions as a seal gas, and the properties of the noro (slag) produced by cutting differ depending on the type of the seal gas, and hydrogen gas has a good detachability and worse in propane. .

In the composition of Noro (slag), hydrogen gas has a high iron content, and propane has a high acid content. There are many. Furthermore, in cutting, the amount of heat required to melt the steel material is less than the amount of heat generated by the oxygen of the steel material, so excess heat is discharged to the environment.

 [0063] When the difference between hydrogen gas cutting and propane gas cutting was examined, (Table 3)

The results shown in (Table 4) were obtained.

[0064] [Table 3]

 For hydrogen cutting

[0065] [Table 4]

 For propane cutting

As shown in (Table 3) and (Table 4), the excess heat of hydrogen gas cutting is 898KJ, while that of propane gas cutting is 1128KJ.

[0066] Next, when examining the release of heat that has an influence on the work environment, the released heat can be considered as heat that directly affects the surroundings by cutting work, such as radiant heat. On the other hand, the heat transferred to the material to be cut is considered to affect the surroundings by radiation, convection, transmission, heat storage, etc. from the surface. This heat can be mitigated by local exhaust or local cooling.

[0067] Thus, the differences in radiation, convection, transmission, and heat storage between hydrogen gas cutting and propane gas cutting were examined, and the results shown in (Table 5) were obtained.

[0068] [Table 5] Direct heat release (radiant heat) Heat from the material to be cut (convection, transfer, heat storage) Preheating flame Iron cutting part α ratio Preheating flame Iron cutting part a nT ratio

 KJ KJ KJ% KJ KJ LJ% Hydrogen cutting 26. 12 449 474. 90 48. 7 235. 11 449 683. 89 70. 1 Propane cutting 564 100 411. 29 564 975. 10 100 inch

As shown in (Table 5), the heat released directly affecting the work environment is about 50% of the propane gas cutting in the case of hydrogen gas cutting.

[0069] The thermal effects on the surrounding environment can be summarized as shown in (Table 6). (Table 6) shows the results of actual temperature changes in the work area of the work house.

 [0070] [Table 6]

It is noticeable that the temperature rise is smaller in the case of hydrogen gas cutting.

 [0071] In addition, the thermal effect on the surrounding environment that can be considered from the heat balance is less in hydrogen gas cutting than in propylene gas cutting. The thermal effect that directly affects the cutting is in hydrogen gas cutting. This is 49% of propane gas cutting, and the heat effect from the material to be cut is 70% of propane gas cutting in hydrogen gas cutting.

 [0072] Considering the effects of temperature change and heat balance in the work area, (Heat that has a direct influence when cutting 0.49) X (Heat from material to be cut 0.7) = 0.34 In addition, the temperature rise in the work house is 7/20. 4 = 0.34, indicating that hydrogen gas cutting is more effective.

 [0073] Regarding the influence on the surrounding environment other than the above, as shown in (Table 7), the generation amount of dust (fume) that does not generate carbon dioxide from the preheating flame is halved in the hydrogen gas cutting. For this reason, the exhaust treatment load in the work house is reduced.

[0074] [Table 7] Carbon dioxide concentration increase Dust concentration increase ppm ratio (%) mg / m ³ ratio (D Hydrogen cutting No increase 0 5. 2 41.6 Propane cutting 4000 or more 100 12. 5 100

With regard to the impact on work efficiency, etc., hydrogen gas cutting can increase the cutting speed, and as shown in (Table 8), cutting work time can be made more efficient, and hydrogen gas cutting can be achieved. Then, the flammable gas cylinder storage area can be reduced, and the oxygen consumption can be reduced.

[Table 8]

なお、前記切断試験は、換気のない条件で行ったものであるので、換気および切 断部位への局所排気を行えば、温度上昇をさらに抑制することができるため、水素ガ ス切断では、長時間の使用にお 、ても作業環境温度を低減ィ匕することが可能である 図 7は本発明に係る切断方法の実施形態 2を説明するための原子炉切断作業の 説明図であり、 60は原子炉の炉心槽、 61は図 2〜図 5に示す火炎トーチ 16などの水 素ガス切断用の装置を備えた走行体、 62は、走行体 61の走行ガイドを行うため、炉 心槽 60の外周壁に合わせて周囲に設置された走行路であって、走行路 62は、走行 体 61と共に炉心槽 60の外壁を上下移動するように、本例ではプーリと駆動ベルトな ど力もなる走行路移動駆動機構 63が設置されて 、る。 [0077] さらに、 64は、炉心槽 60,走行体 61,走行路移動駆動機構 63の外周を覆う作業 ノ、ウスであって、外部力も遮断された密閉空間を形成している。また、走行体 61,走 行路移動駆動機構 63は作業ハウス 64から遠隔操作可能な構成になっている。

Since the cutting test was conducted under conditions without ventilation, the temperature rise could be further suppressed if ventilation and local exhaust to the cut site were performed. Even in the use of time, the working environment temperature can be reduced. FIG. 7 is an explanatory diagram of a nuclear reactor cutting operation for explaining Embodiment 2 of the cutting method according to the present invention. Represents a reactor core tank, 61 represents a traveling body equipped with a hydrogen gas cutting device such as the flame torch 16 shown in FIGS. 2 to 5, and 62 represents a reactor core tank for guiding the traveling body 61 to travel. In this example, the driving path 62 also has a force such as a pulley and a driving belt so as to move up and down the outer wall of the reactor core 60 together with the traveling body 61. A travel path moving drive mechanism 63 is installed. [0077] Furthermore, 64 is an operation node or a mouse that covers the outer periphery of the core tank 60, the traveling body 61, and the traveling path movement drive mechanism 63, and forms a sealed space in which external force is also blocked. In addition, the traveling body 61 and the traveling path moving drive mechanism 63 are configured to be remotely operated from the work house 64.

 FIG. 8 is a configuration diagram showing a related structure of the traveling body in the second embodiment. The traveling path 62 is provided with a rail 65 for guiding the movement of the traveling body 61. A main control device 66 is mounted on the top. Also, above the traveling body 61, there is a hose hanging frame portion 70 for laying a signal line to the external controller 67 or a cord for supplying an electric power source (power source) 68, a hose 69 and the like. is set up.

 FIG. 9 is a block diagram showing the configuration of the main control device in Embodiment 2. 71 is the same configuration as that of the hydrogen Z oxygen electrolysis unit 17 in Embodiment 1, and water to hydrogen. 72 is a water electrolysis hydrogen / oxygen separation generator that generates gas and oxygen gas by electrolysis, 72 is an oxygen generator that generates oxygen gas and nitrogen gas (only oxygen gas! / ヽ), 73 A valve driving unit for opening and closing a valve (not shown) for supplying the hydrogen gas and oxygen gas for branching to pre-heating or cutting and branching to an appropriate position; 74 for hydrogen gas, oxygen gas Alternatively, a measurement sensor for measuring the amount of electric power used, 75 is a traveling body drive unit that drives and controls the traveling of the traveling body 61, and 76 is a control unit that also has power, such as a CPU (central processing unit) that controls the respective units.

 [0080] In the second embodiment having the above-described configuration, the traveling body 61 is described in the first embodiment with respect to the core tank 60 that is powerful such as a steel material while being controlled by the traveling body driving unit 75. Similarly, hydrogen gas is cut. The traveling body 61 moves around the core tank 60 while being guided by the rail 65 of the traveling path 62, and after the cutting of the peripheral portion of the cutting portion is completed, the traveling path moving drive mechanism 63 performs the next operation in the core tank 60. Both the traveling path 62 and the traveling body 61 are moved up and down to the periphery of the cutting part.

 [0081] When the hydrogen gas is cut off, the water electrolysis-type hydrogen-oxygen separation generator 71 and the oxygen generator 72 are started, and the valve drive unit 73 adds hydrogen gas to the flame torch 16 (propane gas is added if necessary). ) Is supplied to generate a preheating flame for preheating the part to be cut, and oxygen gas for cutting is supplied.

[0082] Then, as explained in FIG. 4, each part of the core tank 60 is sequentially rotated by hydrogen gas cutting. Rough cutting is performed in the form of cuts and blocks. This cut member is further transported to a work knife 1 shown in FIG. 1 and cut into an appropriate size for processing.

 Control of each unit of the second embodiment is performed by exchanging signals with each unit in the external controller 67 and the control unit 76 of the main control device 66.

 [0084] In the second embodiment, the radioactive gas house is also used to cut the reactor core tank 60, which is a member to be cut, having a radioactive substance in the sealed work house 64 using the hydrogen gas cutting method. The effect of preventing scattering inside and outside is great, and the work of cutting the reactor core 60 inside the work 64 can be performed safely. Therefore, compared with other conventional thermal cutting methods, The risk of contamination exposure and contamination spread can be reduced.

 [0085] In the second embodiment, the hydrogen gas cutting in the working knife 64 eliminates the need for the operator to always enter the working knife 64 and the hydrogen gas cutting of the flame torch 16 or the like. The traveling body 61 equipped with the device for driving can be driven to automatically cut the core tank 60, which is a member to be cut, so that the worker's operational safety is significantly improved.

 [0086] By the way, the specific temperature regulation in Japan's occupational safety and health regulations is only 37 ° C for underground work, and the specific temperature regulation limit value at the manufacturing site. Does not exist at all. However, as a guideline for the work environment, there is a heat environment that assesses the thermal stress of workers based on the JIS Z 8504 index.

 [0087] However, in the United States, ACGIH (American Industrial Hygienists Conference) has standards for working temperature environments. In this standard, the permissible standard concentration (WB GT) by work intensity and work time is shown, and the temperature correction count of the clothes is exemplified as a feature of this permissible standard.

 [0088] Acceptable criteria for temperature environment indicate the limit of high temperature stress that almost all workers would be able to work with even if they are repeatedly exposed to the conditions, and adapt to the high temperature environment. However, it is possible to work without exceeding the body temperature (rectal temperature) iS 38 ° C of almost all workers wearing normal work clothes and appropriately supplementing water and salt. The conditions are shown.

[0089] Therefore, the verification result in the closed work house by hydrogen cutting according to the present embodiment is referred to as the above-mentioned finger. When compared with the needle and the reference, the remarkable effect of this embodiment is understood.

 [0090] (Table 9) is a list of WBGT reference values to be examined, FIG. 10 is a diagram showing the relationship between the test results of this embodiment and the WBGT reference values, and FIG. 11 is the test results of this embodiment. It is a figure which shows the relationship with a discomfort index.

 [0091] [Table 9]

上述したように、本実施形態のような作業ハウス内において、水素ガス切断の場合

As described above, in the case of hydrogen gas cutting in a work house like this embodiment

However, in the case of propane gas cutting, the initial value of 21.5 ° C was increased to 28.5 ° C, while the initial value of 21.5 ° C was 41.9 ° C. Rose to C.

 This will be examined with reference to FIG. 10 and FIG. In FIG. 10, in the case of hydrogen gas cutting according to this embodiment, the JIS guidelines are satisfied, the US standard is low, and the power is almost satisfactory in a humidity environment. Propane gas cutting also satisfies the underground labor standards. Nao.

 [0093] In FIG. 11, the hydrogen gas cutting does not provide a comfortable working environment, but the propane gas cutting working environment shows a marked improvement from the situation in which everyone feels uncomfortable. The

 [0094] Since the hydrogen gas used in the above embodiment has a wide explosion range, it is necessary to cope with a fire and explosion when used in a work house that is separated and sealed, but the hydrogen gas of this embodiment is used. The gas supply uses a hydrogen Z oxygen electrolyzer configured to independently extract hydrogen gas and oxygen gas by electrolysis of water, so the amount of hydrogen gas in the hydrogen gas supply system (piping) is small. If the pressure is maintained at a positive pressure, explosions can be prevented.

[0095] Further, in the method of extracting oxygen-hydrogen gas by electrolysis of water, a mixture of combustible gases is used. Although it has been proposed to remove the explosion range by combination, since the calorific value is larger than that of hydrogen gas and combustible gas is mixed, the temperature reduction effect as in this embodiment cannot be expected.

 [0096] Further, in the hydrogen gas cutting in the present embodiment, the re-welding of the cut surface is eliminated, and the amount of generated hydrogen is reduced to about 1Z2. Furthermore, it has been verified that it can be easily peeled off with little generation of noro. As a result, the reliability of remote operation and automation can be improved, and the temperature of the work environment can be lowered, reducing the thermal load on the monitoring Z control device required for automation and improving the reliability of the entire system. This makes it easier to implement automation as in the second embodiment.

 [0097] The hydrogen gas supply source and supply method may be other means other than the electrolysis of water or the configuration using a hydrogen gas cylinder. The configuration described in the present embodiment is excellent. The force is not limited to this configuration.

 Industrial applicability

[0098] The present invention adheres to or contains substances harmful to the human body, radioactive substances, persistent organic pollutants (for example, dioxin, PCB, etc.), substances that cause serious diseases such as carcinogenesis (for example, asbestos). It is effective as gas cutting that enables cutting in a favorable work environment in a closed work space such as a special house that is isolated from the surroundings in a sealed state. .

 Brief Description of Drawings

 FIG. 1 is a plan view showing a schematic configuration of a work site for explaining Embodiment 1 of a cutting method according to the present invention.

 [Fig. 2] A-A cross section of Fig. 1 at the work site of Embodiment 1.

 FIG. 3 is a schematic configuration diagram of a water electrolysis-type hydrogen-oxygen separation generator as an example of the hydrogen-Z oxygen electrolysis apparatus in Embodiment 1.

 FIG. 4 is a block diagram showing the configuration of a gas outflow control device in Embodiment 1.

 FIG. 5 is a cross-sectional view for explaining a crater portion and a cutting state of the flame torch according to the first embodiment.

FIG. 6 is a diagram showing the relationship between the hydrogen gas concentration and the combustion rate in Embodiment 1.

[FIG. 7] Reactor cutting operation for explaining Embodiment 2 of the cutting method according to the present invention. Figure

 FIG. 8 is a configuration diagram showing a related structure of the traveling body in the second embodiment.

 FIG. 9 is a block diagram showing the configuration of the main control device in the second embodiment.

[Fig. 10] Diagram showing the relationship between the test results of this embodiment and the WBGT reference value

 FIG. 11 is a graph showing the relationship between the test results and discomfort index of the present embodiment.

 [Fig. 12] Plan view showing the schematic configuration of the work site of the conventional gas cutting method

 [Fig. 13] BB cross section in the conventional example of Fig. 12.

Explanation of symbols

1 work house

2 Cutting platform

4 Material to be cut

 14 Oxygen and combustible gas storage

 16 flame torch

 17 Hydrogen Z oxygen electrolyzer

 21 Hydrogen gas separation tank

 22 Oxygen gas separation tank

 25 Water replenishment tank

 37 Pronon gas storage tank

 42 Control unit

 43 Mixing Z supply section

 44 Operation input section

 50 Preheating gas passage

 51 Oxygen gas passage

 52 Preheating flame

 53 Cutting oxygen stream

 60 Reactor core tank

 61 Running body

62 road Traveling path moving drive mechanism

Working house

Main control device Water electrolysis type hydrogen oxygen separation generator Oxygen generator

Valve drive

Running body drive

Control unit

Claims

The scope of the claims  [1] A cutting method that cuts the member to a predetermined size in a sealed space so that the harmful substance does not scatter to the outside in order to cut the member to which harmful substances adhere or contain. There,  A cutting target member is installed in the sealed space, and a flame torch having a gas outlet diameter selected corresponding to the thickness of the cutting target member is installed in the sealed space so as to face the cutting site. Part force Hydrogen gas and supporting oxygen gas are ejected and ignited, and the cutting part is preheated with a generating flame, and oxygen gas is ejected from the other part of the flame torch to generate a cutting oxygen stream, and the cutting is performed. A cutting method in a closed working space for handling harmful substances, characterized in that the cutting site is cut by cutting and burning with an oxygen stream.  [2] The gas outlet diameter of the flame torch is selected so that a gas quantity for obtaining the amount of gas combustion heat required for cutting with respect to the maximum thickness of the target member to be cut is jetted. Cutting method in a closed work space that handles hazardous substances as described in 1.  [3] The gas cutting state in the target member is made uniform by adjusting the moving speed of the flame torch in accordance with specifications such as the thickness and material of the target member to be cut. Or a cutting method in a closed work space that handles the hazardous substances described in 2.  4. The cutting method in a closed work space for handling harmful substances according to claim 1, wherein a carbon-containing gas is mixed into the hydrogen gas.  [5] The cutting method in a closed work space for handling harmful substances according to claim 4, wherein the mixing ratio of the carbon-containing gas to the hydrogen gas is 50% or less, preferably 20% or less. .