JP2007038179A - Gas mixer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas mixer which has a structure able to well and stably maintain the mixing precision from beginning of mixing to ending in the gas mixer. <P>SOLUTION: The gas mixer has a base gas pipe 10 for supplying a base gas, an additive-gas pipe 20 for supplying an additive gas, and a mixture-gas pipe 30 for discharging a mixture gas which is mixed with above mentioned both gases, wherein the gas mixer has a laminar-flow element for the base gas 16 arranged between the base-gas pipe 10 and the mixture-gas pipe 30, a laminar-flow element for the additive gas 26 arranged between the additive-gas pipe 20 and the mixture-gas pipe 30, and an equalizing valve 40 arranged in the added-gas pipe 20 in the flowing-in side of the laminar-flow element for the additive gas 26 to equalize the pressure of the gas flowing-in side of the laminar-flow element for the base gas 16 and the laminar-flow element for additive gas 26, and the laminar element for the base gas 16 and the laminar element for additive gas 26 carry out flow controlling due to a pressure difference generating in the upper flowing part and the lower flowing part by determining the flow-rate sectional area according to the mixture ratio of the base gas and the additive gas in the mixture gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas mixing apparatus that mixes a plurality of gases, for example, a base gas and an additive gas, with a specific composition, and more particularly, to a configuration of a gas mixing apparatus that provides stable mixing accuracy.

  Conventionally, the flow control of the base gas and the additive gas in the gas mixing apparatus uses a differential pressure method using an area type flow meter, a thermal volume flow meter, an orifice, or the like. That is, in a gas mixing device in which a flow meter and a valve are installed in each of the base gas and additive gas pipes and the outlet side of the valve is connected to one pipe, each valve is opened by visual inspection. The degree of mixing was adjusted to obtain a mixed gas having a desired mixing ratio.

However, in the case of a mixing device that uses an area-type flow meter as a flow meter, the flow accuracy of the flow meter has an error of ± 5% in each flow rate, so that a good mixing accuracy cannot be obtained. was there.
In addition, in the case of a mixing device using a thermal volume flow meter, the flow rate accuracy of the flow meter is ± 0.5% to 1% and the mixing accuracy is good, but at the start of the mixing operation and at the end of the mixing operation, the thermal type It was impossible to obtain stable mixing accuracy by the unstable flow rate control derived from the operation principle of the volumetric flow meter.
Furthermore, in the case of a mixing device that uses an area-type flow meter or a thermal volumetric flow meter as the flow meter, if the back pressure is applied to the outlet side regardless of the flow meter method, the mixing accuracy is greatly affected. There was a problem of getting worse.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas mixing apparatus capable of maintaining a good and stable mixing accuracy from the start to the end of the mixing operation.

In order to achieve the above object, claim 1 has a base gas pipe 10 for supplying a base gas, an additive gas pipe 20 for supplying an additive gas, and a mixed gas pipe 30 for flowing out a mixed gas obtained by mixing the gases. The gas mixing apparatus is characterized by including the following configuration.
A base gas laminar flow element 16 provided between the base gas pipe 10 and the mixed gas pipe 30;
An additive gas laminar flow element 26 provided between the additive gas pipe 20 and the mixed gas pipe 30;
A pressure equalizing valve 40 provided in the addition gas pipe 20 on the inflow side of the additive gas laminar flow element 26 in order to make the gas inflow side pressure of the base gas laminar flow element 16 and the additive gas laminar flow element 26 the same pressure;
It has.
The base gas laminar flow element 16 and the additive gas laminar flow element 26 are configured by setting the flow cross-sectional area in accordance with the mixing ratio of the base gas and the additive gas in the mixed gas.

  In the gas mixing apparatus according to claim 1, the buffer tank 80 for temporarily storing the mixed gas is connected to the mixed gas pipe 30 in the gas mixing apparatus of the first aspect, and the pressure on the outflow side of each laminar flow element 16, 26 is set to the set pressure. Therefore, a constant differential pressure valve 60 is provided on the gas inflow side of the buffer tank 80.

  According to the gas mixing device of the present invention, by using the base gas laminar flow element 16 and the additive gas laminar flow element 26, the flow rate is controlled by the differential pressure generated in the upstream part and the downstream part. Therefore, the mixed gas can be stably supplied while maintaining the high mixing accuracy (± 0.3% FS or less) in the flow range.

An example of an embodiment of a gas mixing apparatus of the present invention will be described with reference to the drawings.
The gas mixing apparatus 1 includes a base gas pipe 10 that supplies a base gas, an additive gas pipe 20 that supplies an additive gas, and a mixed gas pipe 30 that flows out a mixed gas obtained by mixing the gases. Yes.
The base gas pipe 10 and the additive gas pipe 20 are filters provided to introduce high-pressure gas supplied from, for example, a gas cylinder through an inlet joint, and to remove dust contained in each supply gas via the inlet valves 11 and 21. 12 and 22, passes through check valves 13 and 23 provided to prevent backflow in the event of an abnormality, and is configured to reduce the pressure to a desired pressure by pressure regulators 14 and 24 to stabilize the supply pressure. ing. Further, a pressure gauge 83 for detecting the primary pressure is connected to the inlet side of the pressure regulators 14 and 24.

  A pressure equalizing valve 40 is connected to the outlet side of the pressure regulator 24 of the additive gas pipe 20, and the outlet pressure of the pressure regulator 14 of the base gas pipe 10 is branched and supplied to the pressure equalizing valve 40 as a pilot pressure. Due to the functions of the pilot pressure and the pressure equalizing valve 40, the outlet pressures of the base gas pipe 10 and the additive gas pipe 20 become the same pressure.

As shown in FIG. 2, the pressure equalizing valve 40 is provided with a small-diameter primary chamber 41 and a large-diameter secondary chamber 42 in the regulating valve main body 40a, and the primary chamber 41 and the secondary chamber 42 are communicated with both chambers. A valve chamber 43 having a diameter larger than that of the primary chamber and smaller than that of the secondary chamber is formed. The secondary chamber 42 is formed by sandwiching a diaphragm 46 sandwiched by a diaphragm mounting screw 44 and a diaphragm mounting nut 45 between the regulating valve main body 40a and the regulating valve cover 40b.
A lid 40c is attached to the center of the regulating valve cover 40b via an O-ring, and a hole 46 for supplying pilot pressure is formed on the side of the lid, and a diaphragm mounting nut 45 and a spring receiver 47 are provided. A correction spring 48 is mounted between the two. Further, the position of the spring receiver 47 can be adjusted by an adjustment screw 49 attached to the head of the lid, so that the pressing force of the correction spring 48 toward the diaphragm 46 is finely adjusted. .

  A valve seat 51 having a valve hole 50 in the center is mounted in the valve chamber 43, and a valve seat 52 is mounted around the valve hole 50. An adjusting valve rod 53 having a large diameter on the primary chamber side is inserted into the valve hole 50 to form a valve between the valve seat 52 and connected to an adjusting valve guide 54 disposed in the valve seat 51. A buffer spring 55 is interposed between the valve seat 51 and the adjusting valve guide 54. The upper part of the regulating valve guide 54 can come into contact with the lower surface of the diaphragm mounting screw 42. The primary chamber 41 communicates with the inflow port 56 and the secondary chamber 42 communicates with the outflow port 57.

  According to the structure of the pressure equalizing valve 40 described above, the outlet pressure of the pressure regulator 14 of the base gas pipe 10 is supplied as a pilot pressure, and by adjusting the pressing force of the correction spring 48 against the pressing force of the buffer spring 55, The pressure in the secondary chamber 42 can be the same as the pilot pressure (having the function of adjusting the pilot pressure and the outlet pressure of the pressure equalizing valve to the same pressure), and the base gas pipe 10 and the additive gas pipe 20 The outlet pressure becomes the same pressure.

  The base gas pipe 10 is connected to the base gas laminar flow element 16 via the pressure sensor 15, and the outlet side of the laminar flow element 16 is connected to the mixed gas pipe 30 via the air operating valve 17. The outlet side of the pressure equalizing valve 40 of the additive gas pipe 20 is connected to the additive gas laminar flow element 26 via the pressure sensor 25, and the outlet side of the laminar flow element 26 is mixed gas pipe via the air operating valve 27. 30.

  As shown in FIG. 3, the base gas laminar flow element 16 and the additive gas laminar flow element 26 are configured by bundling a large number of thin tubes 19 made of stainless steel in a stainless steel pipe 18. If the differential pressure on the outlet side is kept constant, a differential pressure type flow rate control laminar flow element in which a gas flow rate according to the number of thin tubes 19 (total area of the cross-sectional area of the thin tubes 19) flows is formed. Each laminar flow element may be an aggregate of a plurality of stainless steel tubes 18.

That is, by applying the same pressure to the inlet of each differential pressure type flow control laminar flow element on the base gas side and additive gas side, and obtaining the same differential pressure from the outlet, a stable flow rate from the outlet side. And high mixing accuracy can always be ensured.
If the pressure difference between the inlet side and the outlet side is constant, uniform mixing accuracy from 0 to the maximum flow rate can be obtained. By setting the maximum flow rate to the user's required flow rate and confirming the required flow rate in advance, a gas mixing device specialized in high accuracy can be obtained by manufacturing a laminar flow element that matches the required flow rate. .

  Accordingly, since the pressure on the outlet side of the laminar flow elements 16 and 26 greatly affects the mixing accuracy, a constant differential pressure valve 60 having a back pressure adjustment function is connected to the mixed gas pipe 30. A buffer tank 80 for temporarily storing the mixed gas is connected to the outlet side. That is, the pressure on the outflow side of each laminar flow element 16, 26 is maintained at a constant set pressure by the constant differential pressure valve 60 provided on the gas inflow side of the buffer tank 80.

  According to the above structure, the outlet pressure of the pressure regulator 14 on the base gas piping side and the outlet pressure of the pressure equalizing valve 40 can always maintain the same pressure. The supply pressure to the differential pressure type flow control laminar flow element must be the same on the base gas pipe side and the additive gas pipe side, and the total pressure of the thin tubes 19 in each laminar flow element 16, 26 by making the same pressure. The flow rate can be secured at a constant ratio according to the cross-sectional area ratio, and the mixing accuracy can be maintained with high accuracy.

  As shown in FIG. 4, the constant differential pressure valve 60 is provided with a valve hole 61 in the center of the adjustment valve body 60 a, and a diaphragm 65 in which a diaphragm chamber 62 communicating with the valve hole 61 is sandwiched and fixed by an adjustment valve 63 and a diaphragm receiver 64. The valve seat 66 is fixed to the tip of the regulating valve 63 located in the diaphragm chamber 62. The positions of the adjusting valve 63 and the diaphragm receiver 64 are pressed by a spring 68 via an adjusting valve guide 67, and the pressing force of the spring 68 can be adjusted by a pressure adjusting push screw 69. The regulating valve main body 60a is covered with regulating valve main body covers 60b and 60c. The diaphragm chamber 62 is connected to the gas inlet 70 and the valve hole is connected to the 61 gas outlet 72.

  Accordingly, when the pressure of the spring 68 is adjusted by the pressure adjusting push screw 69 and the gas flows from the gas inlet 70 with the valve seat 66 of the adjusting valve 63 closing the valve hole 61 via the diaphragm 65, the diaphragm flows. Since the pressure of the chamber 62 rises and the diaphragm 65 is pushed up against the pressing force of the spring 68 and the diaphragm chamber 62 reaches a constant pressure, the valve hole 61 is operated to be opened. Since the pressure valve 60 has a function of adjusting the back pressure in the gas mixing pipe when the pressure exceeds the set pressure, a constant differential pressure can always be secured at both ends of each laminar flow element 16, 26.

  A pressure sensor 81 is connected to the buffer tank 80, and when the pressure detected by the pressure sensor 81 is equal to or higher than a certain value, the air operating valves 17, 18 mounted on the outlet side of the laminar flow elements 16, 26. Is configured to close.

  Therefore, according to the above structure, the mixed gas mixed at a constant flow rate can be stored in the buffer tank 80.

On the outlet side of the buffer tank 80, a pressure regulator 82 for reducing the pressure to a desired constant pressure, a pressure gauge 83, and an on-off valve 84 are sequentially connected, and a mixed gas outlet pipe 90 leading to the mixed gas outlet and an on-off valve 85 are connected. Branching to a blow gas pipe 91 leading to the blow gas outlet. This is because when the gas mixing device is used for the first time, the on-off valve 84 is opened, the on-off valve 85 is closed, gas flows only through the blow gas pipe 91, and unnecessary gas existing in each pipe is discharged from the blow gas outlet. This is because the gas flows out and then the on-off valve 85 is closed and the on-off valve 84 is opened to allow the mixed gas to flow through the mixed gas outflow pipe 90.
Pressure gauges 83 are respectively installed on the inlet side of the pressure regulator 14 of the base gas pipe 10 and on the inlet and outlet sides of the pressure regulator 24 of the additive gas pipe 20 to detect the gas pressure at this position. Yes.

FIG. 5 is a piping flow diagram showing another example of the gas mixing device. In this example, unlike the gas mixing device of FIG. 1, the buffer tank that temporarily stores the mixed gas is excluded. Parts having the same configuration as in FIG. 1 are denoted by the same reference numerals.
By removing the buffer tank, the mixed gas pipe 30 is directly connected to the mixed gas outlet, and the mixed gas mixed on the outlet side of each laminar flow element 16, 26 can flow out from the mixed gas outlet. Further, since the buffer tank is not connected, a constant differential pressure valve, a pressure sensor, and an air operation valve for making the inlet side pressure of the buffer tank uniform are unnecessary.
According to the gas mixing apparatus of this example, when a constant flow gas is obtained from the mixed gas outlet, the highly accurate mixed gas can be supplied with a simple configuration.

  According to the gas mixing device having the above-described structure, the flow rate is controlled by the differential pressure generated in the upstream portion and the downstream portion via the laminar flow element, and by combining the pressure equalizing valve and the constant differential pressure valve, in the specified flow range, Mixing accuracy can be supplied with high accuracy of ± 0.3% FS or less. In addition, in the case of a conventional mixing device using an area type flow meter and a thermal type volume flow meter, it is necessary to set both the pressure and the flow rate. It is possible to reliably supply a highly accurate mixed gas.

It is a piping flowchart which shows the piping structure of the gas mixing apparatus as an example of embodiment of this invention. It is sectional explanatory drawing of the pressure equalizing valve used for the gas mixing apparatus of this invention. The laminar flow element used for the gas mixing apparatus of this invention is shown, (a) is external appearance explanatory drawing, (b) is (a) AA sectional view explanatory drawing. It is a section explanatory view of the constant differential pressure valve used for the gas mixing device of the present invention. It is a piping flowchart which shows the piping structure of the other example of a gas mixing apparatus.

Explanation of sign

DESCRIPTION OF SYMBOLS 1 Gas mixing apparatus 10 Base gas piping 20 Additional gas piping 11, 21 Inlet valve 12, 22 Filter 13, 23 Check valve 14, 24 Pressure regulator 15, 25 Pressure sensor 16, 26 Laminar flow element 17, 27 Air operation valve 18 Stainless steel pipe 19 Narrow pipe 30 Mixed gas piping 40 Pressure equalizing valve 60 Constant differential pressure valve 80 Buffer tank 81 Pressure sensor 82 Pressure regulator 83 Pressure gauge 84,85 On-off valve 90 Mixed gas outlet piping 91 Blow gas piping

Claims (2)

A gas mixing device having a base gas pipe for supplying a base gas, an additive gas pipe for supplying an additive gas, and a mixed gas pipe for flowing out a mixed gas obtained by mixing the gases,
A laminar flow element for base gas provided between the base gas pipe and the mixed gas pipe;
A laminar flow element for additive gas provided between the additive gas pipe and the mixed gas pipe;
A pressure equalizing valve provided in the additional gas piping on the inflow side of the laminar flow element for additive gas in order to make the gas inflow side pressure of the laminar flow element for base gas and the laminar flow element for additive gas the same pressure,
The base gas laminar flow element and additive gas laminar flow element have a flow cross-sectional area set in accordance with the mixing ratio of the base gas and additive gas in the mixed gas. 2. A buffer tank for temporarily storing a mixed gas is connected to the mixed gas pipe, and a constant differential pressure valve is provided on the gas inflow side of the buffer tank to set the pressure on the outflow side of each laminar flow element to a set pressure. The gas mixing device according to 1.

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