Abstract:
The method for parallel operation of moisture generating reactors according to the present invention operates so that an orifice, provided with an orifice hole having a predetermined opening diameter, is disposed on a mixed-gas inlet side of each of a plurality of moisture generating reactors connected in parallel with each other, and mixed gas G consisting of hydrogen and oxygen is supplied from a mixer to each of the moisture generating reactors through each orifice, and the flows of moisture generated by the moisture generating reactors are combined, and the resulting combined moisture is supplied to an apparatus that uses high-purity water. Thus, a need to increase the amount of high-purity water supply is met by allowing a plurality of moisture generating reactors to perform a parallel water generating operation by branching off a mixed gas consisting of H 2  and O 2  by using a simple orifice construction.

Description:
This is a National Phase Application in the United States of International Patent Application No. PCT/JP2007/000419 filed Apr. 17, 2007. The entire disclosure of the above patent application is hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a method for the parallel operation of moisture-generating reactors that is used in, for example, semiconductor manufacturing facilities, or chemical manufacturing facilities, and that enables each moisture generating reactor to perform a stable parallel operation in a predetermined amount of moisture generation merely by inserting orifices, each of which has an appropriate opening diameter, into the source-gas supply lines of the moisture generating reactors, respectively, that perform a parallel operation without using a special apparatus that divides the flow of source gas and supplies the gas. 
     BACKGROUND OF THE INVENTION 
     For example, in silicon-dioxide-film adhesion processing according to a moisture oxidation method used by semiconductor manufacturing facilities, a high-purity water supply is required, and, in usual cases, the necessary high-purity moisture is supplied by a moisture generating reactor as shown in, for example,  FIG. 8 . 
     More specifically, this moisture generating reactor is structured so that, as disclosed by International Publication No. WO97/28085 and by Japanese Patent No. 3639469, a reactor body  1  having a space  4  thereinside is formed by assembling an inlet-side reactor body member  2  and an outlet-side reactor body member  3  together so as to face each other, and the reactor body  1  is provided with a source gas inlet  5 , a moisture gas outlet  6 , a reflector  7 , and a reflector  8 , and, furthermore, a platinum coating film  9  is formed on an inner surface of the outlet-side reactor body member  3 . 
     When moisture is generated, mixed gas G consisting of oxygen O 2  and hydrogen H 2  is first supplied from the source gas inlet  5  into the space  4 , and is then stirred by the reflectors  7  and  8  while oxygen O 2  and hydrogen H 2  are activated by the catalytic action of the platinum coating film  9 . Thereafter, activated oxygen O 2  and hydrogen H 2  are allowed to instantaneously react with each other in a non-combustion state below a temperature of 450° C., thus generating water. The resulting water is discharged from the moisture gas outlet  6  out of the reactor body  1  in the form of moisture gas W. 
     In spite of the fact that the moisture generating reactor structure, as shown in  FIG. 8 , is very small (for example, about 114 mm in outer diameter and about 35 mm in thickness), the moisture generating reactor can continuously generate moisture gas W of about 2 SLM (which is a moisture gas quantity calculated in a standard state at a temperature of 0° C. and at 1 atmosphere of pressure, wherein SLM is an abbreviation for “Standard Liters per Minute”) by the catalytic reaction performed below a temperature of 400° C. Thus, the moisture generating reactor structure shown in  FIG. 8  has an excellent, practicable effect. 
     However, in the moisture generating reactor shown in  FIG. 8 , if the supply of the source gas G is increased in amount so as to increase the amount of moisture generation, a rise in temperature of the outlet-side reactor body member  3  becomes steep, and the temperature of the internal space of the reactor body  1  will rise and approach the explosive temperature of the source gas G, which is H 2 —O 2  mixed gas, and, as a result, an extremely dangerous state will be reached. Additionally, if the supply of the source gas G is increased in amount, the rate of reaction between hydrogen H 2  and oxygen O 2  will fall, and oxygen O 2  and hydrogen H 2  will enter into, and mix with, moisture gas W without allowing oxygen O 2  and/or hydrogen H 2  to react with each other, and, as a result, various disadvantages will occur on the process side where the moisture gas W is used. Additionally, if the temperature of the reactor body  1  rises, the platinum coating film  9  formed on the inner wall surface of the outlet-side reactor body member  3  will peel and fall off, and, as a result, a significant deterioration in catalytic action will result. 
     On the other hand, in order to avoid the occurrence of the disadvantages mentioned above, a moisture generating reactor structured to advance heat dissipation from the reactor body  1  has been developed by providing cooling fins  10  and  11  on the outer wall surface of the inlet-side reactor body member  2  and on the outer wall surface of the outlet-side reactor body member, respectively, as shown in  FIG. 9 . In  FIG. 9 , reference numeral  12  designates an electric heater that is used to raise the temperature of the moisture generating reactor  1  to nearly 300° C. when the moisture generating reactor  1  is started. 
     However, a problem resides in the fact that the disposition of the cooling fins  10  and  11  leads to a great increase in outside dimensions of the moisture generating reactor  1 , and, if the amount of moisture generation is made, for example, 1.3 times as great as the conventional amount of moisture generation, the volume of the reactor  1  must be tripled, and hence it is impossible to meet the requirement of reducing the moisture generating reactor  1  in size. A possible method for increasing the amount of moisture generation, without using the cooling fins  10  and  11 , is to increase the outside dimensions of the reactor body  1 . However, if the area in which the platinum coating film  9  is formed exceeds a predetermined area, unevenness will occur in the temperature distribution on the inner surface of the outlet-side reactor body member  3  when moisture is generated, and, as a result, the platinum coating film  9  may readily peel off. Therefore, another problem resides in the fact that, if the inner diameter of the reactor body  1  is made, for example, twice or more as large as the conventional one, the frequency of occurrence of peeling off of the platinum coating film  9  will rise steeply, as is well known, and the requirement of increasing the amount of moisture generation cannot be satisfactorily met. 
     Therefore, when employing the above-described type of conventional equipment for supplying moisture gas W, a plurality of moisture generating reactors may be connected in parallel with each other. Then, the flow rate of mixed gas G supplied to each moisture generating reactor is controlled by use of a highly accurate apparatus (i.e., a mixed-gas-flow-dividing-and-supplying apparatus) that divides the flow of the mixed gas G and that supplies the gas to each moisture generating reactor in order to meet the requirement of increasing the amount of moisture generation (i.e., the amount of moisture that needs to be supplied). 
     However, still another problem resides in the fact that the disposition of the highly accurate apparatus for dividing the flow of the mixed gas G, and supplying the gas, brings about not only a steep rise in the amount of equipment employed, but also brings about the need for a large space for the installation of the equipment, and furthermore, it increases costs for the maintenance, or the like, of the mixed-gas-flow-dividing-and-supplying apparatus.
     Patent Literature 1: International Publication No. WO97/28085   Patent Literature 2: Japanese Patent No. 3639469   

     Problems to be Solved by the Invention 
     The present invention has been made to solve the above-mentioned problems occurring in equipment for supplying high-purity moisture used by a conventional moisture generating reactor. Specifically, the present invention has been made to solve (i) the problem of given constraints on meeting the requirement of increasing the amount of to-be-supplied moisture by increasing the moisture generating reactor in size (or in volume) because there is a limit to the enlargement of the moisture generating reactor from the viewpoint of structural factors, such as the durability of the platinum coating catalyst film, and (ii) the problem of the steep rise in equipment costs and in management costs, and in the need for a large installation space for the mixed-gas-flow-dividing-and-supplying apparatus, which are problems caused when the need to increase the amount of to-be-supplied moisture is met by employing the-mixed-gas-flow-dividing-and-supplying apparatus that divides the flow of mixed gas G and that supplies the gas, and by supplying the mixed gas G to a plurality of moisture generating reactors performing a parallel water generating operation. It is therefore a main object of the present invention to provide a method for the parallel operation of moisture generating reactors that is capable of supplying a predetermined amount of mixed gas G to each moisture generating reactor performing a parallel water generating operation by employing a simple mechanism at low cost, which is accurate and capable of easily meeting the need to increase the amount of moisture generation by attaching orifices, each of which has a predetermined inner diameter to mixed-gas supply lines, respectively. Thus, another object of the present invention is to supply mixed gas to the moisture generating reactors performing a parallel operation without requiring a structurally complex apparatus for dividing the flow of mixed gas G and that supplies the gas in amounts required. 
     SUMMARY OF THE INVENTION 
     The invention, in accordance with a first embodiment of the invention, employs an orifice disposed on a mixed-gas inlet side of each of a plurality of moisture generating reactors; an end on an inlet side of each orifice is connected to a mixed gas supply line in parallel; and mixed gas consisting of hydrogen and oxygen is allowed to branch off and is supplied to each of the moisture generating reactors through each of the orifices. 
     The invention, according to a second embodiment, employs orifices that are disposed on the mixed-gas inlet sides of a plurality of moisture generating reactors, respectively; an end on an inlet side of each of the orifices is connected to a mixed-gas supply line in parallel; mixed gas consisting of hydrogen and oxygen is allowed to branch off and is supplied to each of the moisture generating reactors through each of the orifices; ends on moisture-gas outlet sides of the moisture generating reactors are connected in parallel with each other; and moisture generated by each of the moisture generating reactors is supplied along a moisture supply line to an apparatus that uses the moisture. 
     The invention according to a third embodiment modifies the second embodiment so that the apparatus using the moisture is a process chamber used under pressure that is approximately atmospheric pressure. 
     The invention according to a fourth embodiment modifies the second embodiment so that the apparatus using the moisture is a process chamber used under a pressure of 1 to 700 Torr, and the moisture supply line along which moisture generated from the moisture generating reactors is supplied is provided with a depressurizing orifice. 
     The invention according to a fifth embodiment modifies either the first or the second embodiment so that the number of the moisture generating reactors connected in parallel with each other is two; and the orifices disposed on the mixed-gas inlet sides of the moisture generating reactors are equal in opening diameter to each other; and mixed gases that are substantially equal in amount to each other are supplied from the mixed-gas supply lines to each of the moisture generating reactors, respectively. 
     The invention according to a sixth embodiment further modifies the fifth embodiment so that a rated amount of moisture generation for each of the moisture generating reactors is 5 SLM to 10 SLM, and the opening diameter of the orifice disposed on the mixed-gas inlet side is 0.8 to 0.6 mmφ. 
     The invention according to a seventh embodiment further modifies the sixth embodiment so that an internal pressure of each moisture generating reactor has a pressure value of 200 Torr or more. 
     The invention according to an eighth embodiment modifies the first embodiment or the second embodiment so that each moisture generating reactor is structured so that the moisture generating reactor has an internal space, which is achieved by combining an inlet-side reactor body member and an outlet-side reactor body member together so as to face each other; the inlet-side reactor body member is provided with a mixed-gas inlet, whereas the outlet-side reactor body member is provided with a moisture-gas outlet; a platinum coating film is disposed on an inner wall surface of the outlet-side reactor body member; a reflector is disposed in the internal space; and moisture is generated by allowing the hydrogen gas and the oxygen gas of the mixed gas to react with each other by catalytic action of the platinum coating film under a non-combustion state inside the internal space. 
     Effects of the Invention 
     In accordance with the present invention, mixed gas, which is a source gas used to generate moisture, can be allowed to branch off with extreme accuracy by using a flow-dividing structure having a simple construction in which an orifice having a predetermined opening diameter is only disposed on the mixed-gas inlet side of each of the moisture generating reactors connected in parallel with each other, and a large amount of high-purity water can be supplied using a non-combustion type moisture generating reactor that employs a conventional platinum coating catalyst. In other words, according to the present invention, a large amount of high-purity water can be supplied safely, and at lower cost, by using a conventional non-combustion type moisture generating reactor without using a mixed-gas-flow-dividing apparatus that is high in cost, and complex in structure, and without having to enlarge the equipment to supply the large amount of high-purity water. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a system diagram that shows the parallel operation of moisture generating reactors in accordance with a first non-limiting, illustrative embodiment of the present invention. 
         FIG. 2  is a system diagram that shows the parallel operation of moisture generating reactors in accordance with a second non-limiting, illustrative embodiment of the present invention. 
         FIG. 3  is a system diagram in which N 2  gas is supplied instead of mixed gas G, and wherein the state of each divided flow toward each moisture-generating reactor is measured. 
         FIG. 4  shows graphs, each exhibiting arithmetic values of Table 3, in which (a) shows the relationship of the divided-flow error to the flow rate (MFM 1 ), (b) shows the relationship of the divided-flow error to the orifice upstream-side pressure P 2 , (c) shows the relationship between the orifice upstream-side pressure P 2  and the calculated pressure, and (d) shows the relationship between the orifice upstream-side pressure P 2  and the relative divided-flow error (%) of the flow rate. 
         FIG. 5  is a system diagram wherein 17 Standard Liters per Minute (SLM) moisture gas is supplied from two moisture generating reactors to a chamber CH under normal pressure. 
         FIG. 6  is a system diagram showing a moisture supply state created by actual parallel operation using two moisture generating reactors (whose rating is 5 SLM). 
         FIG. 7  is a graph showing one example of test results obtained with respect to the system diagram according to  FIG. 6 . 
         FIG. 8  is a sectional view showing an example of a conventional moisture generating reactor. 
         FIG. 9  is a sectional view showing an example of a conventional moisture generating reactor provided with cooling fins. 
     
    
    
     DESCRIPTION OF SYMBOLS 
     
         
         H 2 : Hydrogen gas 
         O 2 : Oxygen gas 
         N 2 : Nitrogen gas 
         M: Gas mixer that mixes H 2  and O 2    
         G: Mixed gas (Source gas) 
         WG 1 , WG 2 : Moisture generating reactors 
         OR 1 , OR 2 , OR 3 : Orifices 
         S: H 2  gas sensor 
         F: Filter 
         CH: Process chamber 
         P 1 , Pw 1 , Pw 2 , Pc: Pressure gauges 
         W 1 , W 2 , W: Moisture (Moisture gas) lines 
         L 1 , L 2 , L 3 , L 4 : Tube lines 
         MFC 1 , MFM 1 , MFM 2 : Mass flowmeters 
         HTC 1 -HTC 4 : Temperature controllers 
         RG 1 -RG 4 : Pressure regulators 
         V 1 -V 4 : Valves 
         FA 1 , FA 2 : Cooling fans 
         HTM 1 , HTM 2 : Temperature monitors 
           1 : Reactor body 
           2 : Inlet-side reactor body member 
           3 : Outlet-side reactor body member 
           4 : Internal space of the reactor body 
           5 : Mixed-gas inlet (Source-gas inlet) 
           6 : Moisture-gas outlet 
           7 ,  8 : Reflectors 
           9 : Platinum coating film 
           10 ,  11 : Cooling fins 
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Non-limiting illustrative embodiments of the present invention will be hereinafter described with reference to the drawings.  FIG. 1  shows a first illustrative embodiment of the present invention, and depicts an example in which moisture W is supplied to a process chamber CH under normal pressure by use of two moisture generating reactors WG 1  and WG 2 . 
     In  FIG. 1 , H 2  designates hydrogen gas, O 2  designates oxygen gas, N 2  designates nitrogen gas, M designates a gas mixer that mixes H 2  and O 2 , G designates mixed gas, WG 1  and WG 2  designate moisture generating reactors, OR 1  and OR 2  designate orifices, S designates a H 2  sensor, F designates a filter, CH designates a process chamber, P 1 , Pw 1 , Pw 2 , and Pc designate pressure gauges, W 1 , W 2 , and W designate moisture, and L 1 , L 2 , L 3 , and L 4  designate tube lines. 
     The two moisture generating reactors WG 1  and WG 2  used herein are the same in structure, and are made of stainless steel. Each of the moisture generating reactors WG 1  and WG 2  is about 180 mmφ in outer diameter, and is about 37 mm in thickness. A platinum coating film is formed on the inner wall surface of an outlet-side reactor body member of the reactor. Although the two moisture generating reactors, each having the same structure, are connected together in parallel in this non-limiting embodiment of the invention, more than two moisture generating reactors, for example, three to five moisture generating reactors may be connected together in parallel in accordance with the present invention. 
     Each of the orifices OR 1  and OR 2  is formed by boring a predetermined orifice hole (e.g., a circular hole) in a thin stainless steel plate having an outer diameter of about 12 mmφ and a thickness of 0.2 to 1.0 mm to form an orifice or orifice member, and each orifice member is replaceably inserted in an orifice inserter (not shown in the drawings). In this embodiment of the invention, the orifices OR 1  and OR 2 , each of which has an orifice hole of 0.5 to 1.0 mmφ formed therein, are used as described later. 
     Each of the tube lines L 1  to L 4  is formed of a stainless steel tube having an inner diameter of 4.3 mmφ and an outer diameter of 6.35 mmφ, and the process chamber CH that consumes generated moisture W is used to perform various semiconductor processings under normal pressure (i.e., 760 Torr). 
     With reference to  FIG. 1 , mixed gas G supplied from the gas mixer M passes through the mixed gas supply line L 1  and through the orifices OR 1  and OR 2  (0.6 mmφ or 0.7 mmφ), and is supplied to the moisture generating reactors WG 1  and WG 2 . Moistures W 1  and W 2  generated by the reactors WG 1  and WG 2 , respectively, are supplied to the normal-pressure chamber CH through the moisture supply line L 4 . In order to allow mixed gas G to smoothly branch off and be supplied to the two reactors, the relationship P 1 &gt;P W &gt;P C  is required to be established among pressures P 1 , P W , and P C . Additionally, pressure P C  is made smaller (e.g., about 0.02 to 0.03 MPa) than pressure P W  due to pressure loss in the tube lines L 3  and L 4 . 
     Table 1, presented below, shows one example of provisional calculations of the upstream-side pressure P 1  corresponding to the orifices OR 1  and OR 2  when the mixture ratio of H 2  and O 2 , and the moisture-supply flow rate (Standard Cubic Centimeters per Minute, abbreviated “sccm”) to the process chamber CH under normal pressure (760 Torr), are changed under the condition that the opening diameter of each of the orifices OR 1  and OR 2  is 0.6 or 0.7 mmφ. Under these conditions, the estimated value of the pressure can be determined. Equations (2) and (3), provided below, are used as the pressure computing equation in accordance with the present invention, and the length of the tube line, which is formed of a stainless steel tube having an inner diameter of 4 mmφ, is 600 mm to 800 mm. In Table 1, the amount of supply moisture per reactor is shown. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Examination of upstream orifice diameters 0.6 and 0.7 
               
             
          
           
               
                   
                   
                 Calculation 
                   
               
               
                   
                   
                 of subsonic 
                 Examination of upstream 
               
               
                   
                 Calculation 
                 velocity 
                 necessary pressure 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                 of sound 
                 Necessary 
                 Calculation 
                 Calculation 
               
               
                   
                   
                   
                   
                 Excess 
                 Total 
                   
                 velocity 
                 differential 
                 of sound 
                 of subsonic 
               
               
                 H 2   
                 O 2   
                 N 2   
                 H 2 O 
                 O 2   
                 Flow Rate 
                 Orifice 
                 Pressure 
                 pressure 
                 velocity 
                 velocity 
               
               
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (mm) 
                 (Torr abs) 
                 (Torr) 
                 (MPa G) 
                 (MPa G) 
               
               
                   
               
             
          
           
               
                 5000 
                 4000 
                 0 
                 5000 
                 1500 
                 9000 
                 0.6 
                 2174.305 
                 1555.389 
                 0.189 
                 0.207 
               
               
                 5000 
                 3500 
                 0 
                 5000 
                 1000 
                 8500 
                 0.6 
                 1986.777 
                 1298.662 
                 0.164 
                 0.173 
               
               
                 5000 
                 3000 
                 0 
                 5000 
                 500 
                 8000 
                 0.6 
                 1796.626 
                 1061.973 
                 0.138 
                 0.142 
               
               
                 4500 
                 4500 
                 0 
                 4500 
                 2250 
                 9000 
                 0.6 
                 2289.427 
                 1724.453 
                 0.204 
                 0.230 
               
               
                 4500 
                 2700 
                 0 
                 4500 
                 450 
                 7200 
                 0.6 
                 1616.963 
                 860.198 
                 0.114 
                 0.115 
               
               
                 5000 
                 3000 
                 0 
                 5000 
                 500 
                 8000 
                 0.7 
                 1319.970 
                 573.226 
                 0.075 
                 0.076 
               
               
                 4000 
                 2400 
                 0 
                 4000 
                 400 
                 6400 
                 0.7 
                 1055.976 
                 366.865 
                 0.039 
                 0.049 
               
               
                 3000 
                 1800 
                 0 
                 3000 
                 300 
                 4800 
                 0.7 
                 791.982 
                 206.361 
                 0.004 
                 0.028 
               
               
                   
               
             
          
         
       
     
       FIG. 2  shows a second non-limiting, illustrative embodiment of the present invention, and depicts an example in which generated moisture W is supplied from the two moisture generating reactors WG 1  and WG 2  to the process chamber CH, which is used in a depressurized state of 1 to 100 Torr. In accordance with  FIG. 2 , OR 3  designates an orifice disposed on the downstream side of the filter F, and is provided to depressurize generated moisture W supplied to the chamber CH. 
     In this non-limiting, illustrative embodiment of the present invention, in order to allow mixed gas G to smoothly branch off and be supplied to the reactors so that a predetermined amount of generated moisture W 1  and W 2  are supplied from the moisture generating reactors WG 1  and WG 2 , respectively, in the same way as in the first non-limiting, illustrative embodiment shown in  FIG. 1 , each of the moisture generating reactors WG 1  and WG 2  is required to have a pressure of 200 Torr to 900 Torr. The reason is that, if the internal pressure of each of the moisture generating reactors WG 1  and WG 2  falls below 200 Torr, the explosion limit temperature (i.e., explosive temperature) of H 2  gas will be lowered to a temperature of about 350° C. to 400° C. 
     Table 2 shows an example of arithmetic values of the internal pressure P W , and so forth, for the moisture generating reactors WG 1  and WG 2  when the opening diameter of the depressurizing orifice OR 3  is 0.8 mmφ and 1.0 mmφ, and the pressure computing equation, etc., used herein are the same as used in obtaining values shown in Table 1 above. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Examination of orifice diameters 0.8 and 1.0 (for depressurizing) 
               
             
          
           
               
                   
                 Total of two 
                   
                   
               
             
          
           
               
                 Amount of gas introduced per 
                 reactors 
                 Calculation of 
                   
               
               
                 reactor WVG 
                 Total 
                 sound velocity 
               
             
          
           
               
                   
                 Excess 
                 downstream 
                   
                 WVG 
                 Inflow gas to Pc 
               
             
          
           
               
                 H 2   
                 O 2   
                 N 2   
                 H 2 O 
                 O 2   
                 flow rate 
                 Orifice 
                 Pressure 
                 Specific 
                   
                 Flow rate 
               
               
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (mm) 
                 (Torr abs) 
                 gravity 
                 Cv value 
                 m 3 /Hr 
               
               
                   
               
             
          
           
               
                 5000 
                 3500 
                 0 
                 5000 
                 1000 
                 12000 
                 1.0 
                 849.831 
                 0.350575 
                 0.036941 
                 0.72 
               
               
                 5000 
                 3000 
                 0 
                 5000 
                 500 
                 11000 
                 1.0 
                 758.423 
                 0.332288 
                 0.036941 
                 0.66 
               
               
                 4000 
                 3000 
                 0 
                 4000 
                 1000 
                 10000 
                 1.0 
                 716.274 
                 0.358621 
                 0.036941 
                 0.6 
               
               
                 4000 
                 2400 
                 0 
                 4000 
                 400 
                 8800 
                 1.0 
                 606.738 
                 0.332288 
                 0.036941 
                 0.528 
               
               
                 3500 
                 2400 
                 0 
                 3500 
                 650 
                 8300 
                 1.0 
                 585.765 
                 0.348151 
                 0.036941 
                 0.498 
               
               
                 5000 
                 3000 
                 0 
                 5000 
                 500 
                 11000 
                 0.8 
                 1185.036 
                 0.332288 
                 0.023642 
                 0.66 
               
               
                 4000 
                 2400 
                 0 
                 4000 
                 400 
                 8800 
                 0.8 
                 948.029 
                 0.332288 
                 0.023642 
                 0.528 
               
               
                 3500 
                 2000 
                 0 
                 3500 
                 250 
                 7500 
                 0.8 
                 800.833 
                 0.326437 
                 0.023642 
                 0.45 
               
               
                 3000 
                 1800 
                 0 
                 3000 
                 300 
                 6600 
                 0.8 
                 711.022 
                 0.332288 
                 0.023642 
                 0.396 
               
               
                   
               
             
          
         
       
     
     Table 3 shows one example of the arithmetic operation of pressure values on the upstream side of the orifices OR 1  and OR 2 , under the condition that the opening diameter of each of the upstream-side orifices OR 1  and OR 2  is 0.7 mmφ, when the mixing conditions, etc., of mixed gas G are the same as in Table 2. From this data, the outline or curve of the pressure values P 1  on the upstream side of the orifices OR 1  and OR 2  can be determined. 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Examination of orifice diameters 0.8 and 1.0 (for depressurizing) 
               
               
                 Examination of upstream-side (flow-dividing) orifice (An increase in pressure 
               
               
                 from necessary pressure of the depressurizing orifice) 
               
             
          
           
               
                 Amount of gas introduced per reactor 
                   
               
             
          
           
               
                   
                   
                   
                   
                 Excess 
                 Total 
                   
                 Increase in 
                 Upstream 
                   
               
               
                 H 2   
                 O 2   
                 N 2   
                 H 2 O 
                 O 2   
                 Flow rate 
                 Orifice 
                 pressure 
                 pressure 
                 Pressure 
               
               
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (sccm) 
                 (mm) 
                 (Torr) 
                 (Torr abs) 
                 (MPa G) 
               
               
                   
               
             
          
           
               
                 5000 
                 3500 
                 0 
                 5000 
                 1000 
                 8500 
                 0.7 
                 1460 
                 2309.504 
                 0.221023 
               
               
                 5000 
                 3000 
                 0 
                 5000 
                 500 
                 8000 
                 0.7 
                 1320 
                 2078.393 
                 0.188568 
               
               
                 4000 
                 3000 
                 0 
                 4000 
                 1000 
                 7000 
                 0.7 
                 1223 
                 1939.289 
                 0.169034 
               
               
                 4000 
                 2400 
                 0 
                 4000 
                 400 
                 6400 
                 0.7 
                 1056 
                 1662.714 
                 0.130194 
               
               
                 3500 
                 2400 
                 0 
                 3500 
                 650 
                 5900 
                 0.7 
                 1008 
                 1593.657 
                 0.120497 
               
               
                 5000 
                 3000 
                 0 
                 5000 
                 500 
                 8000 
                 0.7 
                 1320 
                 2505.006 
                 0.248477 
               
               
                 4000 
                 2400 
                 0 
                 4000 
                 400 
                 6400 
                 0.7 
                 1056 
                 2004.005 
                 0.178122 
               
               
                 3500 
                 2000 
                 0 
                 3500 
                 250 
                 5500 
                 0.7 
                 896 
                 1696.562 
                 0.134948 
               
               
                 3000 
                 1800 
                 0 
                 3000 
                 300 
                 4800 
                 0.7 
                 792 
                 1503.004 
                 0.107766 
               
               
                   
               
             
          
         
       
     
       FIG. 3  shows a flow circuit in which the state of divided flows of N 2  gas has been examined when N 2  gas is supplied, instead of a mixed gas G, in the parallel operation of the moisture generating reactors in the first non-limiting, illustrative embodiment shown in  FIG. 1 . In  FIG. 3 , MFC 1 , MFM 1 , and MFM 2  designate mass flowmeters, respectively. 
     In the flow circuit shown in  FIG. 3 , the measured value of MFM 1  and the measured value of MFM 2  are proportionate directly to the inflow of mixed gas G into the moisture generating reactors WG 1  and WG 2 , respectively; hence, the amounts of moisture generated in the moisture generating reactors WG 1  and WG 2  can be determined from the measured values of the mass flowmeters MFM 1  and MFM 2 . 
     Table 4, below, shows arithmetic values of a divided-flow error and a pressure error obtained from each measured value when the opening diameter of each of the orifices OR 1  and OR 2 , of  FIG. 3 , is set at 0.7 mmφ, 0.6 mmφ, and 0.5 mmφ. 
     
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                   
                   
                   
                   
                   
                 Pressure 
               
               
                   
                 Upstream 
                 MFM 1   
                 MFM 2   
                 Divided-flow 
                 Mean value 
                 Calculation 
                 error 
               
               
                 Orifice 
                 pressure {circle around (1)} 
                 {circle around (2)} 
                 {circle around (3)} 
                 error 
                 {circle around (2)} and {circle around (3)} 
                 value 
                 {circle around (1)}-{circle around (4)} 
               
               
                 (mm) 
                 (MPa G) 
                 (SLM) 
                 (SLM) 
                 {circle around (2)} and {circle around (3)} % 
                 (SLM) 
                 {circle around (4)} 
                 (MPa) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0.8 
                 0.011 
                 1.15 
                 1.13 
                 1.74% 
                 1.14 
                 0.0014 
                 0.0096 
               
               
                 0.8 
                 0.020 
                 2.69 
                 2.67 
                 0.74% 
                 2.68 
                 0.0077 
                 0.0123 
               
               
                 0.8 
                 0.046 
                 5.19 
                 5.17 
                 0.39% 
                 5.18 
                 0.0288 
                 0.0172 
               
               
                 0.8 
                 0.088 
                 7.63 
                 7.68 
                 −0.66% 
                 7.655 
                 0.0630 
                 0.025 
               
               
                 0.8 
                 0.136 
                 10.13 
                 10.15 
                 −0.20% 
                 10.14 
                 0.110 
                 0.026 
               
               
                 0.7 
                 0.011 
                 1.14 
                 1.13 
                 0.88% 
                 1.135 
                 0.0024 
                 0.0086 
               
               
                 0.7 
                 0.014 
                 1.66 
                 1.64 
                 1.20% 
                 1.65 
                 0.005 
                 0.0090 
               
               
                 0.7 
                 0.017 
                 2.16 
                 2.17 
                 −0.46% 
                 2.165 
                 0.0086 
                 0.0084 
               
               
                 0.7 
                 0.023 
                 2.69 
                 2.65 
                 1.49% 
                 2.67 
                 0.0131 
                 0.0099 
               
               
                 0.7 
                 0.027 
                 3.17 
                 3.18 
                 −0.32% 
                 3.175 
                 0.0185 
                 0.0085 
               
               
                 0.7 
                 0.034 
                 3.69 
                 3.67 
                 0.54% 
                 3.68 
                 0.0248 
                 0.0092 
               
               
                 0.7 
                 0.04 
                 4.2 
                 4.18 
                 0.48% 
                 4.19 
                 0.0322 
                 0.0078 
               
               
                 0.7 
                 0.048 
                 4.69 
                 4.68 
                 0.21% 
                 4.685 
                 0.0402 
                 0.0078 
               
               
                 0.7 
                 0.057 
                 5.17 
                 5.18 
                 −0.19% 
                 5.175 
                 0.0491 
                 0.0079 
               
               
                 0.6 
                 0.036 
                 2.74 
                 2.61 
                 4.74% 
                 2.675 
                 0.0243 
                 0.0117 
               
               
                 0.6 
                 0.045 
                 3.24 
                 3.11 
                 4.01% 
                 3.175 
                 0.0342 
                 0.0108 
               
               
                 0.6 
                 0.061 
                 3.75 
                 3.61 
                 3.73% 
                 3.68 
                 0.046 
                 0.0150 
               
               
                 0.6 
                 0.111 
                 5.30 
                 5.06 
                 4.53% 
                 5.18 
                 0.0911 
                 0.0199 
               
               
                 0.6 
                 0.186 
                 7.41 
                 7.16 
                 3.37% 
                 7.285 
                 0.169 
                 0.0170 
               
               
                 0.6 
                 0.193 
                 7.52 
                 7.27 
                 3.32% 
                 7.395 
                 0.173 
                 0.020 
               
               
                 0.6 
                 0.201 
                 7.79 
                 7.52 
                 3.47% 
                 7.655 
                 0.183 
                 0.018 
               
               
                 0.6 
                 0.210 
                 7.99 
                 7.72 
                 3.38% 
                 7.855 
                 0.19 
                 0.020 
               
               
                 0.6 
                 0.224 
                 8.33 
                 8.03 
                 3.60% 
                 8.18 
                 0.202 
                 0.022 
               
               
                 0.6 
                 0.238 
                 8.74 
                 8.43 
                 3.55% 
                 8.585 
                 0.217 
                 0.021 
               
               
                 0.6 
                 0.258 
                 9.28 
                 8.95 
                 3.56% 
                 9.115 
                 0.237 
                 0.021 
               
               
                 0.6 
                 0.304 
                 10.44 
                 10.06 
                 3.64% 
                 10.25 
                 0.279 
                 0.025 
               
               
                 0.5 
                 0.011 
                 0.61 
                 0.63 
                 −3.28% 
                 0.62 
                 0.0037 
                 0.0073 
               
               
                 0.5 
                 0.017 
                 1.12 
                 1.15 
                 −2.68% 
                 1.135 
                 0.0125 
                 0.0045 
               
               
                 0.5 
                 0.028 
                 1.64 
                 1.66 
                 −1.22% 
                 1.65 
                 0.0264 
                 0.0016 
               
               
                 0.5 
                 0.043 
                 2.16 
                 2.17 
                 −0.46% 
                 2.165 
                 0.0454 
                 −0.0024 
               
               
                 0.5 
                 0.062 
                 2.67 
                 2.68 
                 −0.37% 
                 2.675 
                 0.0694 
                 −0.0074 
               
               
                 0.5 
                 0.088 
                 3.18 
                 3.17 
                 0.31% 
                 3.175 
                 0.0977 
                 −0.0097 
               
               
                 0.5 
                 0.111 
                 3.71 
                 3.66 
                 1.35% 
                 3.685 
                 0.130 
                 −0.019 
               
               
                 0.5 
                 0.134 
                 4.20 
                 4.18 
                 0.48% 
                 4.19 
                 0.161 
                 −0.027 
               
               
                 0.5 
                 0.162 
                 4.70 
                 4.67 
                 0.64% 
                 4.685 
                 0.192 
                 −0.03 
               
               
                 0.5 
                 0.189 
                 5.19 
                 5.16 
                 0.58% 
                 5.175 
                 0.215 
                 −0.026 
               
               
                   
               
             
          
         
       
     
     Figures (a), (b), (c), and (d) of  FIG. 4  are graphs of the arithmetic values compiled in Table 3.  FIG. 4(   a ) shows the relationship of the divided-flow error to the flow rate (MFM 1 ),  FIG. 4(   b ) shows the relationship of the divided-flow error to the orifice upstream-side pressure P 2 ,  FIG. 4(   c ) shows the relationship between the orifice upstream-side pressure P 2  and the calculated pressure, and  FIG. 4(   d ) shows the relationship between the orifice upstream-side pressure P 2  and the relative divided-flow error % of the flow rate. 
     As is apparent from Table 4 and figures (a), (b), (c), and (d) of  FIG. 4 , the divided-flow error ( FIG. 4(   a )) stays below about 5%, and the variation (MFM 1 −MFM 2 /MFC 1 ) also stays below 3%. Therefore, the divided flows created by the orifices OR 1  and OR 2  can be used without, from a practical standpoint, causing any problems, and it is understood that mixed gas G can be allowed to branch off and be supplied to the moisture generating reactors GW 1  and GW 2  by using an extremely simple flow-dividing device. 
     Exemplary Embodiment 1 
       FIG. 5  is a system diagram wherein 17 SLM moisture gas W is supplied to the chamber CH, which operates under normal pressure (760 Torr), using the two moisture generating reactors WG 1  and WG 2 . Table 5, below, shows orifice upstream-side pressures calculated from the flow rate Q and from the sectional area S on the assumption that a critical condition is established between the upper and lower streams of the orifices OR 1  and OR 2 , shown in the system diagram of  FIG. 5 . 
     Formula (1) is the operational expression of the flow rate Q. 
     
       
         
           
             
               
                 
                   
                     [ 
                     
                       Formula 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       1 
                     
                     ] 
                   
                   ⁢ 
                   
                       
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   Q 
                   = 
                   
                     
                       
                         SP 
                         H 
                       
                       
                         
                           T 
                           H 
                         
                       
                     
                     · 
                     
                       C 
                       ′ 
                     
                     · 
                     
                       ( 
                       
                         F 
                         . 
                         F 
                         . 
                       
                       ) 
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     In this equation, Formula I, Q is a flow rate of gas, S is an orifice sectional area, T H  is a temperature of gas, P H  is upstream pressure, C is the constant 187021, and C′ is a correction (C×0.82) calculated from an actual flow rate. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                   
                 Sectional 
                   
                   
                 Stream below 
               
               
                 Orifice 
                 area S 
                   
                 Stream above orifice 
                 orifice 
               
             
          
           
               
                 mm 
                 mm 2   
                 kPa abs 
                 Torr 
                 Torr 
               
               
                   
               
             
          
           
               
                 0.65 
                 0.332 
                 202.6 
                 1519.5 
                 759.8 
               
               
                 0.6 
                 0.283 
                 237.7 
                 1783.4 
                 891.7 
               
               
                 0.55 
                 0.238 
                 282.9 
                 2122.3 
                 1061.2 
               
               
                 0.5 
                 0.196 
                 342.4 
                 2568.0 
                 1284.0 
               
               
                 0.45 
                 0.159 
                 422.7 
                 3170.4 
                 1585.2 
               
               
                 0.4 
                 0.126 
                 534.9 
                 4012.6 
                 2006.3 
               
               
                   
               
             
          
         
       
     
     Exemplary Embodiment 2 
     In the same system diagrammed as that of  FIG. 5 , pressure P 1  and pressure P 2  on the upstream side (i.e., tube upstream side) and on the downstream side (i.e., above the orifices OR 1  and OR 2 ) of the mass flowmeter MFC have been respectively calculated when mixed gas G consisting of H 2  and O 2 , corresponding to moisture generation of 17 SLM, is allowed to flow. Formulas (2) and (3) are operational expressions therefor. 
                     [     Formula   ⁢           ⁢   2     ]     ⁢                                   Q   =     C   ⁡     (       P   1     -     P   2       )               (   2   )                 [     Formula   ⁢           ⁢   3     ]     ⁢                                   C   =       π     8   ⁢           ⁢   η       ⁢       a   ⁢           ⁢   4     l     ⁢     (         p   1     +     p   2       2     )               (   3   )               
In the equations of Formulas (2) and (3), Q is a flow rate of gas, P 1  is upstream pressure, P 2  is downstream pressure, a is an orifice radius, and η is a viscosity coefficient of the gas. When a tube pressure loss (H 2 /O 2 ) is calculated, the viscosity coefficient of mixed gas G cannot be calculated and, hence, a calculation is performed both for H 2  and for O 2  as shown in Table 6 (the viscosity coefficient η of H 2  is 0.88×10 −5  Pa·sec, and the viscosity coefficient ζ of O 2  is 1.75×10 −5  Pa·sec).
 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                   
                   
                   
                 Stream 
                   
                   
               
               
                   
                 Sectional 
                 Stream above 
                 below 
                 Upper stream 
                 Upper stream (O 2 ) 
               
               
                 Orifice 
                 area S 
                 orifice 
                 orifice 
                 (H 2 ) through tube 
                 through tube 
               
             
          
           
               
                 mm 
                 mm 2   
                 kPa abs 
                 Torr 
                 Torr 
                 kPa abs 
                 Torr 
                 kPa abs 
                 Torr 
               
               
                   
               
             
          
           
               
                 0.8 
                 0.503 
                 133.7 
                 1003.3 
                 501.6 
                 187.4 
                 1406 
                 240.2 
                 1801 
               
               
                 0.75 
                 0.442 
                 152.2 
                 1141.3 
                 570.7 
                 201.0 
                 1508 
                 250.9 
                 1882 
               
               
                 0.7 
                 0.385 
                 174.7 
                 1310.2 
                 655.1 
                 218.5 
                 1639 
                 265.1 
                 1989 
               
               
                 0.65 
                 0.353 
                 190.7 
                 1430.2 
                 715.1 
                 231.5 
                 1737 
                 275.9 
                 2070 
               
               
                 0.66 
                 0.342 
                 196.5 
                 1473.8 
                 736.9 
                 236.3 
                 1773 
                 280.0 
                 2100 
               
               
                   
               
             
          
         
       
     
     Exemplary Embodiment 3 
       FIG. 6  is a system diagram showing parallel operation of two moisture generating reactors WG 1  and WG 2  performed according to the present invention. In  FIG. 6 , RG 1  to RG 4  designate pressure regulators, V 1  to V 4  designate valves, FA 1  and FA 2  designate cooling fans, HTC 1 , HTC 2 , HTC 3 , and HTC 4  designate temperature controllers, and HTM 1   1  and HTM 2  designate temperature monitors. The outlet side of each of the moisture generating reactors WG 1  and WG 2  opens toward the atmosphere. 
     The temperature controllers HTC 1  and HTC 4  are used to keep the temperature of the moisture generating reactors WG 1  and WG 2  at 350° C., and the cooling fans FA 1  and FA 2  are controllably operated, if necessary. The temperature controllers HTC 2  and HTC 3  are used to keep the temperature of the tube lines at 140° C. Each of the orifices OR 1  and OR 2  is an orifice whose opening diameter is 0.7 mmφ, and each of the moisture generating reactors WG 1  and WG 2  is a 5 SLM type reactor having an outer diameter of 180 mmφ. 
     According to the system diagram of  FIG. 6 , mixed gas G (H 2 =6 SLM to 10 SLM, O 2 =7 SLM) flows from the gas mixer M to each of the moisture generating reactors WG 1  and WG 2  through the orifices OR 1  and OR 2 , and supply pressures P O  and P H  of O 2  gas and H 2  gas, respectively, and the concentration of unreacted H 2 , and a change in temperature caused when moisture was generated, were measured. The amount of moisture to be generated was set between 6 SLM and 10 SLM in the single moisture generating reactor. 
     Table 7 shows moisture generation test results corresponding to operation of the system shown in  FIG. 6 .  FIG. 7  is a graph outlining the test results. 
     
       
         
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
               
                   
               
               
                   
                   
                   
                 HTC 1 -R 1   
                 HTM 1 -R 1   
                 HTC 4 -R 2   
                 HTM 2 -R 2   
                 Unreacted H 2   
                   
                   
               
               
                   
                   
                   
                 Temperature 
                 Temperature 
                 Temperature 
                 Temperature 
                 Concentration 
               
               
                 H 2   
                 O 2   
                 H 2 O 
                 Max. 
                 Max. 
                 Max. 
                 Max. 
                 Max. 
                 P H   
                 P O   
               
               
                 (SLM) 
                 (SLM) 
                 (SLM) 
                 (° C.) 
                 (° C.) 
                 (° C.) 
                 (° C.) 
                 (Vol %) 
                 (MPaG) 
                 (MPaG) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 6 
                 7 
                 6 
                 357 
                 362 
                 358 
                 347 
                 0.08 
                 0.091 
                 0.089 
               
               
                 7 
                 7 
                 6 
                 350 
                 350 
                 351 
                 357 
                 0.08 
                 0.094 
                 0.093 
               
               
                 8 
                 7 
                 6 
                 353 
                 353 
                 353 
                 360 
                 0.08 
                 0.099 
                 0.097 
               
               
                 9 
                 7 
                 6 
                 366 
                 364 
                 360 
                 364 
                 0.08 
                 0.102 
                 0.100 
               
               
                 10 
                 7 
                 6 
                 359 
                 366 
                 366 
                 367 
                 0.08 
                 0.105 
                 0.103 
               
               
                   
               
             
          
         
       
     
     As is apparent from  FIG. 7  and Table 7, it is understood that mixed gases G, each of which is equal in amount, flow into the moisture reactors WG 1  and WG 2 , respectively, by flow division, and the two moisture reactors cause an equal rise in temperature by substantially the same moisture generation reaction. Additionally, it is understood from  FIG. 7  and Table 7 that the concentration of unreacted H 2  is also kept stably at a low value by operation of the two moisture generation reactors in parallel. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be applied not only to semiconductor manufacturing facilities, and to chemical manufacturing facilities, but also to high-purity water supply facilities, or the like, in the food processing industry or the pharmaceutical industry.