JP2008275185A - Humidified gas supply method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a humidified gas supply method capable of efficiently supplying a humidified gas of prescribed water amount and prescribed flow rate with a simple constitution while dispensing with precise control of water temperature, and a dew point measuring device. <P>SOLUTION: In this humidified gas supply method for mixing a saturated moist gas supplied from a humidifying passage 12 having a humidifier 16 and a dry gas supplied from a dry gas passage 13 to produce the humidified gas of predetermined flow rate and predetermined moisture amount, and supplying the same to a humidified gas use destination from the humidified gas supply passage 15, the pressure and temperature of the saturated moist gas are measured, and a flow rate of the saturated moist gas and a flow rate of the dry gas are respectively set on the basis of the moisture amount of the saturated moist gas and the moisture amount and flow rate of the humidified gas calculated on the basis of the measured pressure and temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a humidified gas supply method, and more particularly to a method of supplying a humidified gas containing a necessary amount of water widely used in heat treatment, oxidation, a firing furnace, and the like.

  A humidified gas with a predetermined amount of moisture added to the gas is used for heat treatment, oxidation, firing, etc. Furthermore, the moisture in the gas is used as an oxygen source in the plasma atmosphere for sterilization, surface treatment, organic contamination removal, etching, etc. It is used. In addition, in a method in which moisture is gradually decreased from a conditioned gas for drying that does not require rapid drying, it is necessary to quantitatively supply a desired humidified gas in advance.

As a means for humidifying gas (humidification source), dry water can be obtained by utilizing a method of obtaining water vapor by heating and evaporating liquid water, and using water vapor permeation characteristics such as fluorine-based and polyimide-based hollow fiber membranes or flat membranes. There is a method of obtaining moisture gas by adding moisture. In addition, as a method of controlling the dew point in the humidified gas, the temperature of the humidification source is controlled and a saturated amount of water is added at the temperature and pressure, or if the temperature is lower than the control temperature, the obtained humidified gas is dried. There is a method of controlling the amount of moisture by diluting with gas (for example, see Patent Documents 1 to 3).
JP-A-8-61718 JP 2002-180117 A Japanese Patent Laid-Open No. 2-80511

  When heating or cooling water to the required dew point temperature and saturating moisture under the temperature and pressure conditions, it is essential to control the water temperature. If the water temperature control accuracy is low, the amount of added water will fluctuate and be stable. A gas with a dew point cannot be obtained. Moreover, in the method of diluting by mixing dry gas with wet gas saturated with moisture, the dew point of the humidified gas is controlled by measuring the dew point of the humidified gas, so that the dew point of the humidified gas is measured. Dew point measuring equipment is required. The dew point measuring device is very low in reliability and durability compared to temperature measuring devices, flow measuring devices, flow control devices, etc., and when the dew point measuring device breaks down, there is a problem that the whole process does not work. .

  Therefore, an object of the present invention is to provide a humidified gas supply method capable of efficiently supplying a humidified gas having a predetermined moisture amount and a predetermined flow rate with a simple configuration without requiring precise water temperature control and dew point measurement equipment.

  In order to achieve the above object, the humidified gas supply method of the present invention mixes a saturated wet gas supplied from a humidifying path having a humidifier and a dry gas supplied from a dry gas path, and has a preset flow rate. In the humidified gas supply method for generating a humidified gas with a predetermined amount of moisture and supplying the humidified gas to the user of the humidified gas, the pressure and temperature of the saturated wet gas are measured and calculated based on the measured pressure and temperature. The flow rate of the saturated wet gas and the flow rate of the dry gas are respectively set from the moisture content of the saturated wet gas and the moisture content and flow rate of the humidified gas.

  Further, by correcting the calculated moisture content of the saturated wet gas with a preset parameter based on the measured pressure and temperature, it is possible to cope with a change in the moisture content of the saturated wet gas due to film deterioration or the like. .

  According to the humidified gas supply method of the present invention, the amount of moisture contained in the saturated gas is determined by the pressure and temperature of the gas at that time, so that it depends on the amount of moisture and the flow rate of the humidified gas supplied to the user. By setting and mixing the flow rate of the saturated wet gas and the flow rate of the dry gas, the humidified gas having a predetermined moisture amount can be supplied to the user at a predetermined flow rate. Therefore, precise temperature control and precise dew point measurement equipment are not required.

  FIG. 1 is a system diagram showing an example of a humidified gas supply apparatus to which the humidified gas supply method of the present invention is applied. This humidified gas supply device includes a raw material dry gas supply path 11 for supplying a raw material dry gas, a humidifying path 12 and a dry gas path 13 branched from the raw material dry gas supply path 11, and saturated wetness supplied from the humidified path 12. A gas mixing unit 14 for mixing the gas and the drying gas for dilution supplied from the dry gas path 13, and a humidified gas generated by mixing the saturated wet gas and the dry gas in the gas mixing unit 14 are used. A humidifying gas supply path 15 for supplying to the humidifier, a humidifier 16 provided in the humidifying path 12, a pressure gauge (PI) 17 for measuring the pressure of the saturated wet gas that has been saturated with water by the humidifier 16, and a saturation A thermometer (TI) 18 for measuring the temperature of the wet gas, flow rate controllers (MFCs) 19 and 20 provided in the humidification path 12 and the dry gas path 13, respectively, and the pressure gauge 7 and a controller (PLC) for setting the gas flow rate in the flow rate regulators 19 and 20 based on the pressure and temperature of the saturated wet gas measured by the thermometer 18 and the moisture content and flow rate of the humidified gas set in advance, respectively. 21.

  The humidifier 16 includes a humidifying film 16a, a water tank 16b, and a pump 16c for circulating water through the humidifying film 16a and the water tank 16b. The humidifying membrane 16a is made of a water vapor permeable membrane such as a fluorine-based or polyimide-based hollow fiber membrane or a flat membrane as in the prior art, and has a sufficiently large humidifying capacity for the amount of gas to be humidified. By using a membrane that always obtains a wet gas having a dew point equivalent to the water temperature even when the gas amount changes, the moisture content in the gas after humidification that has passed through the humidifier 16 is the temperature at that time, The pressure is saturated.

  In addition, a heat exchanger 16d is disposed on the inlet side of the humidifier 16, and the temperature of the dry gas flowing into the humidifier 16 is changed to the temperature of water vapor that is in contact with the humidifier film 16a, that is, the humidified film 16a by the pump 16c. The temperature is adjusted to be close to the circulating water temperature. Furthermore, if necessary, temperature adjustment means may be provided in the water tank 16b or the circulation path to adjust the water temperature to the optimum temperature range for humidification.

  The humidified gas supply apparatus having such a configuration supplies a humidified gas having a predetermined moisture amount to the user at a predetermined flow rate based on the specification of the humidified gas user input from the input unit 21a. Hereinafter, a method for supplying the humidified gas to the user will be described. In addition, since the dry gas used as a raw material can be obtained by arbitrary means, detailed description is abbreviate | omitted.

First, the flow rate F (m ³ / h) and the water content W (g / m ³ ) of the humidified gas set in advance at the humidified gas use destination are input to the controller 21 from the input means 21a such as a keyboard. The controller 21 sets the flow rate of the flow rate adjusters 19 and 20 based on the input flow rate F and moisture content W. Here, the saturated vapor pressure Vp (Pa) under atmospheric pressure at the temperature T (° C.) can be approximated by the following formula (1).
ln (Vp) = − 6097T ⁻¹ + 21.24−2.711 × 10 ⁻² T + 1.694 × 10 ⁻⁵ T ² +2.434 ln (T) (1)
Furthermore, the saturated water content Ws (g / m ³ ) at the pressure P (MPa) can be approximated by the following formula (2).
Ws = Vp × 1.019 × (0.1013 / (P + 0.1013)) × (1 / (0.47 × (273 + T)) (2)
On the other hand, the flow rate Fw (m ³ / h) of the wet gas necessary for obtaining the moisture amount required in the humidified gas from the flow rate F and the moisture amount W of the humidified gas supplied to the user is expressed by the following formula (3 ).
Fw = F × W / Ws (3)
Further, the flow rate Fo (m ³ / h) of the dry gas for diluting the wet gas can be obtained by the following formula (4).
Fo = F−Fw (4)

  Therefore, by inputting the pressure P (MPa) and the temperature T (° C.) measured by the pressure gauge 17 and the thermometer 18 respectively into the expressions (1) and (2), the saturated water content Ws in the wet gas is obtained. Can be obtained.

  The necessary wet gas flow rate Fw can be obtained by the above equation (3) from the obtained saturated water content Ws, the humidified gas flow rate F and the water content W input in advance. From the gas flow rate Fw and the humidified gas flow rate F, the required dry gas flow rate Fo can be obtained from the equation (4).

  The controller 21 sets the flow rate regulator 19 in the humidification path 12 based on the wet gas flow rate Fw thus obtained, and the flow rate regulator 20 in the dry gas path 13 based on the dry gas flow rate Fo. By setting, wet gas and dry gas can be mixed in the gas mixing unit 14 and a humidified gas having a flow rate F and a moisture amount W set in advance can be supplied from the humidified gas supply path 15 to the user.

  This makes it possible to supply a desired humidified gas to a user only by using a relatively inexpensive and highly reliable pressure gauge 17 and thermometer 18 as measuring instruments, and the equipment cost and operating cost for supplying the humidified gas. Can be reduced.

  On the other hand, in the above-described method, since the dew point of the humidified gas that is actually manufactured and supplied to the user is measured and the measurement value is not fed back, the deterioration of the film in the humidifier 16 and the reproducibility of the flow rate control There is a possibility that the reproduction accuracy may be hindered by long-term or equipment operation due to the drift due to deterioration of the process and the bias value inherent to the process and equipment. As a countermeasure against these problems, a method of adding and subtracting a parameter (C) for adding or subtracting a certain amount of gas before calculating the wet gas flow rate Fw after calculating the saturated water amount Ws is taken. Can do. The value of the parameter can be set by periodically checking and setting the dew point of the humidified gas that is actually produced with a calibrated dew point meter, etc., and the process does not depend on the reliability and durability of the dew point meter. Reproducibility is high and a constant humidified gas can be obtained.

  The parameter may be a fixed value, but the saturated water content Ws is larger as the temperature is higher and is larger as the pressure P is lower. Therefore, the parameter is preferably set as a function of temperature, pressure, and flow rate.

  Further, instead of calculating the saturated vapor pressure Vp logarithmically by calculating the equation (1) using the temperature measured by the thermometer 18, a temperature region is set in advance, and the saturated vapor pressure Vp in each temperature region is set. A relatively inexpensive commercially available sequencer that cannot perform the calculation of the above formula (1) including a complicated logarithmic calculation is set as the controller 21 by setting so as to calculate with a calculation formula approximating a straight line. And the cost of the apparatus can be further reduced.

  A calculation formula approximating a straight line for obtaining the saturated vapor pressure Vp used at this time can be set as follows. For example, when the temperature range of the wet gas is 0 to 40 ° C., the temperature range is set in increments of 5 ° C. such as 0 ° C. to less than 5 ° C., 5 ° C. to less than 10 ° C., Vp = 52.5 × T + 611 at 5 ° C., Vp = 71.2 × T + 516 at 5-10 ° C., Vp = 95.4 × T + 274 at 10-15 ° C., Vp = 126.6 × T-194 at 15-20 ° C., 20-20 Vp = 166.2 × T-986 at 25 ° C., Vp = 215.2 × T-2211 at 25-30 ° C., Vp = 275.8 × T-4029 at 30-35 ° C., Vp = 315.4 × T at 35-40 ° C. By setting a calculation formula at -6675, an approximate value of the saturated vapor pressure Vp in each temperature region can be obtained by a simple calculation formula.

It is a systematic diagram which shows an example of the humidification gas supply apparatus to which the humidification gas supply method of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Raw material dry gas supply path, 12 ... Humidification path, 13 ... Dry gas path, 14 ... Gas mixing part, 15 ... Humidification gas supply path, 16 ... Humidifier, 16a ... Humidification film, 16b ... Water tank, 16c ... Pump, 16d ... Heat exchanger, 17 ... Pressure gauge, 18 ... Thermometer, 19, 20 ... Flow controller, 21 ... Controller, 21a ... Input means

Claims (2)

  Mixing the saturated wet gas supplied from the humidification path with the humidifier and the dry gas supplied from the dry gas path to generate a humidified gas with a preset amount of moisture at a preset flow rate to humidify In a humidified gas supply method for supplying gas to a user, a moisture content of the saturated humid gas calculated based on the measured pressure and temperature, a moisture content and a flow rate of the humidified gas measured based on the measured pressure and temperature And setting the flow rate of the saturated wet gas and the flow rate of the dry gas.   2. The humidified gas supply method according to claim 1, wherein the calculated moisture content of the saturated wet gas is corrected with a preset parameter based on the measured pressure and temperature.

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