JPH0327064B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a precision gas specific gravity measuring device using the outflow method established in JIS K2301-1980 "Analysis and Testing Methods for Fuel Gas and Natural Gas" and the like. Conventional technology The Bunsen-Schilling method is often used as a simple and precise gas specific gravity measurement method using the outflow method.
The measurement accuracy is said to be limited to 2% due to (a) error in measuring outflow time, (b) error depending on orifice diameter, (c) error due to water vapor, and (d) error due to sample gas temperature. Precise flow-through method that eliminates each factor that causes errors related to (a), (b), (c), and (d) and allows for measurement of specific gravity of gases from hydrogen to butane with high accuracy of ±0.5%. A gas specific gravity measuring device is disclosed in Japanese Patent Publication No. 59-13694 (Japanese Patent Application No. 51-72821). The precision gas specific gravity measuring device using the conventional outflow method described in this Japanese Patent Publication No. 59-13694 is as shown in Fig. 1. (b) An orifice with a diameter larger than the JIS diameter that allows gas to be discharged from this bag via another solenoid valve 5; (c) Both legs are filled with water 9, and one leg is The bag 7 in the section
a U-shaped outer body 8 having approximately the same diameter and containing a U-shaped outer body 8; A first control electrode 13, first and second measurement electrodes 11, 12, and a second control electrode 10 arranged so as to be in contact with the water surface when the water surface rises and falls due to discharge.
and (e) a counter coupled to the first and second measuring electrodes 11, 12 so as to measure the passing time interval when the water surface passes through the first and second measuring electrodes 11, 12 and descends. 18; (f) calculation display devices 19 and 20 coupled to this counter so as to calculate and display the measured value of this counter 18; and (g) when the water surface passes through the first control electrode 13 and descends. When the water level rises and reaches the second control electrode 10, the first solenoid valve is closed and the other solenoid valve 5 is opened. a sequence device 21 coupled to the control electrode and the solenoid valve to open the other solenoid valve. According to this precision gas specific gravity measuring device using the outflow method, (a') It is possible to avoid outflow time measurement errors by electronically measuring time using the measurement electrodes 11 and 12 and the counter 18, ( b') By arranging the outflow time measuring electrodes 11 and 12 as far away from the measuring electrode as possible, errors depending on the small orifice diameter can be avoided; (c') The contact between the measuring gas and water can be prevented by Errors caused by water vapor can be avoided by cutting off with the impermeable bag 7, and (d') The residence time of the measurement gas in the fluid-impermeable bag 7 can be increased or the constant temperature device 3 can be used. By doing so, it is possible to avoid errors caused by the temperature of the measured gas, and as a result, by avoiding at least the three errors related to (a'), (b'), and (c'), a high accuracy of ±0.5% can be achieved. It was possible to measure the specific gravity of gases from hydrogen to butane. Problems to be Solved by the Invention In the conventional precision gas specific gravity measuring device using the outflow method, the physical characteristics of the orifice plate 6 change due to changes in the environmental temperature, and as a result, the gas outflow time varies. The occurrence of measurement errors could not be avoided. Therefore, the technical problem of the present invention (as defined in claim 1) is to avoid changes in the physical properties of the orifice plate 6 due to changes in ambient temperature. In addition, in the precision gas specific gravity measurement device using the conventional outflow method, components such as H ₂ in the sample gas are removed from the bag 7.
The water passes through and accumulates in the upper end of the leg 22 of the U-shaped outer shell 8, which increases the water head pressure, making it unavoidable that measurement errors will occur. Therefore, the technical problem of the present invention (as set forth in claim 2) is to avoid accumulation of specific components in the sample gas within the U-shaped outer shell 8. Means for Solving the Problem In order to solve the above technical problem, this invention [described in claim 1] has the following features as shown in FIGS. 2 and 3: an inflatable fluid-impermeable bag 7 into which gas can be introduced via the solenoid valve 2 or 4; (b) an orifice with a diameter larger than the JIS diameter through which gas can be discharged from the bag through another solenoid valve 5; c) a U-shaped outer body 8 having approximately the same diameter, with water 9 filled in both legs 22 and 23, and the bag 7 stored in one leg 22; (d) the other of the legs; A first control electrode is arranged at a height that is successively farther away from the water surface of the bag 7, and is arranged so as to be in contact with the water surface when the water surface rises and falls as gas is introduced into and discharged from the bag 7. 13, first and second measurement electrodes 11, 12 and second control electrode 1
0 and (e) coupled to the first and second measuring electrodes 11, 12 so as to measure the passing time interval when the water surface passes through the first and second measuring electrodes 11, 12 and descends. a counter 18; (f) calculation and display devices 19 and 20 coupled to this counter so as to calculate and display the measured values of this counter 18; (g) when the water surface passes through the first control electrode 13; When descending, the other solenoid valve 5 is closed and the most closed solenoid valve 2 or 4 is opened, but when the water level rises and reaches the second control electrode 10, the first solenoid valve is closed. An orifice plate 6 provided with the orifice in a precision gas specific gravity measurement device using an outflow method, comprising a sequence device 21 coupled to the control electrode and the solenoid valve so as to close and open the other solenoid valve.
is embedded in the heat sink 26 so that the orifice and the through hole 27 of the heat sink are in communication with each other, and a heating element 28 is provided to heat the heat sink, so as to keep the temperature of the heat sink constant.
control means 29, 30, 3 for detecting the temperature of the heat sink and controlling the supply of current to the heating element;
1, 32, and 33 are provided. In addition, in order to solve the above technical problem, this invention [described in claim 2]
As shown in FIG. and (c) a U-shaped outer body 8 of approximately the same diameter, with both legs 22 and 23 filled with water 9, and one leg 22 containing the bag 7. (d) The other leg portion 23 of the two leg portions is placed at a height position that is successively farther away from the water surface, and is capable of preventing the water surface from rising or falling as gas is introduced into and discharged from the bag 7. The first control electrode 13, the first and second measurement electrodes 11, 12, and the second control electrode 1 are arranged so as to be in contact with the water surface.
0 and (e) coupled to the first and second measuring electrodes 11, 12 so as to measure the passing time interval when the water surface passes through the first and second measuring electrodes 11, 12 and descends. a counter 18; (f) calculation and display devices 19 and 20 coupled to this counter so as to calculate and display the measured values of this counter 18; (g) when the water surface passes through the first control electrode 13; When descending, the other solenoid valve 5 is closed and the most closed solenoid valve 2 or 4 is opened, but when the water level rises and reaches the second control electrode 10, the first solenoid valve is closed. An orifice plate 6 provided with the orifice in a precision gas specific gravity measurement device using an outflow method, comprising a sequence device 21 coupled to the control electrode and the solenoid valve so as to close and open the other solenoid valve.
is embedded in the heat sink 26 so that the orifice and the through hole 27 of the heat sink are in communication with each other, and a heating element 28 is provided to heat the heat sink, so as to keep the temperature of the heat sink constant.
control means 29, 30, 3 for detecting the temperature of the heat sink and controlling the supply of current to the heating element;
1, 32, and 33, one end of a tube 34 communicating with the inside of this leg is attached to the upper end of the one leg 22, and the other open end of this tube 34 and the one end are connected. A solenoid valve 35 is provided between them, and this solenoid valve is connected to the sequence device 21 so as to open and close at predetermined time intervals. Function This invention will be explained as follows. As shown in Figure 2, the reference gas, e.g.
Air with a certain pressure of 1,000 ℃ is introduced into the constant temperature device 3 from the sample gas inlet 1 through the solenoid valve 2. At this time, solenoid valve 2 and solenoid valve 4 are open, and only solenoid valve 5 is closed. The air is then kept at a constant temperature in a constant temperature device 3, passes through a solenoid valve 4, enters an inflatable fluid-impermeable bag 7, and inflates the air. In addition, if you do not use constant temperature device 3,
The solenoid valve 2 becomes unnecessary, and air enters the bag 7 from the sample gas inlet 1 through the solenoid valve 4 with a certain pressure, and the bag 7 is inflated. Therefore, the water level at the right leg 23 of the U-shaped outer body 8 having the same diameter and containing the water 9 rises. When the water level rises and reaches the control electrode 10, the solenoid valves 2 and 4 are also closed by the action of the sequence device 21 via the amplifier 15 and held in that state for several seconds to temporarily stop fluctuations in internal pressure, and then the solenoid valves 2 and 4 are closed. 5
only opens. Then, the air passes through the solenoid valve 5 due to the potential energy of the water surface of the right leg 23 of the U-shaped outer body 8, and passes through the through hole 27 of the heat sink 26.
and the orifice of the orifice plate 6 before being ejected to the outside. At this time, the water surface of the right leg 23 of the U-shaped outer body 8 goes down, and when it goes down, the water surface passes through the measuring electrode 11 and the measuring electrode 12 in sequence, and the time interval is set by the amplifier 16, 17 through the counter 18 (for example, Takeda Riken TR
-5764 Universal Counter). The measured value (outflow time) is stored in the calculation device 19 and displayed on the display device 20. Furthermore, when the water surface passes the control electrode 13, only the solenoid valve 5 is closed by the action of the sequence device 21 via the amplifier 14, and the solenoid valves 2 and 4 are opened, and air flows through the constant temperature device 3 in the same way as described above. It is placed in the pass bag 7, and the same process is carried out thereafter. When these operations are repeated and a certain indication for air is obtained, the same measurement operations are then repeated for the sample gas. Then, the specific gravity of the sample gas is calculated by the arithmetic unit 19 based on the following equation from the outflow time of the air and the outflow time of the sample gas, and the specific gravity of the sample gas is displayed on the display device 20. S=T ² / _S / T ² / _a S: Specific gravity of sample gas Ts: Outflow time of sample gas Ta: Outflow time of air During this measurement operation, the heat sink 26 is positioned at an appropriate position as shown in FIG. A thermistor-type thermometer transmitter 29 embedded in (preferably approximately in the center), an amplifier 30, a comparator 31, and a power supply 32
and a switch 33,
The temperature of the heat sink 26 is converted into a current by the thermistor type thermometer transmitter 29, and this current is sent to the comparator 31 via the amplifier 30 and compared with a reference value, which opens and closes the switch 33 of the power supply 32. 33 (the other end is grounded or connected to a power source) to keep the temperature of the heat sink 26 and orifice plate 6 constant. Furthermore, as shown in FIG.
1 opens and closes the solenoid valve 35 at predetermined time intervals, gas components such as H ₂ that have passed through the bag 7 and accumulated in the upper end of the leg 22 of the U-shaped outer body 8 are removed. By discharging into the atmosphere from the open other end of the pipe 34, an increase in the water head can be avoided. Effects of the invention This invention has the following unique effects. Keep the temperature of the orifice plate 6 constant, for example
An example of the variation in the air outflow time Ta when the temperature is maintained at 40°C is as follows.

[Table] In other words, in this case, it can be said that there is almost no change in the air outflow time Ta due to changes in the environmental temperature, for example, the room temperature. On the other hand, an example of the variation in the air outflow time Ta when the orifice plate 6 changes depending on the environmental temperature is as follows.

[Table] Therefore, it is clear that the air outflow time Ta varies greatly depending on the room temperature. An example of the variation of the air outflow time Ta in the case of bubbles or accumulated gas components 5 c.c. is as follows.

[Table] It is clear that errors due to accumulation of gas components can be eliminated. Embodiment In the embodiment of the invention shown in FIG. 2, the inflatable fluid-impermeable bag 7 is preferably an inflatable fluid-impermeable bag made of a suitable synthetic resin, although a plastic bag is preferred. can be used. Further, the conduit connecting the orifice plate 6 and the bag 7 may be separate from the conduit connecting the constant temperature device 3 and the bag 7. The diameter of the orifice of orifice plate 6 is
1.00mmφ or 0.7mmφ was used. Also, a thermistor type thermometer transmitter 29 and an amplifier 3
0, comparator 31, and switch 33,
A thermostatic switch may be used to control the supply of current to heating element 28. In FIGS. 2 and 3, the heating element 28 is wrapped around the heat sink 26, in which case a metal heating element, particularly a nichrome wire, is preferred.
However, in the case of a non-metallic heating element, for example a heating element made of a silicon carbide compound, it may be inserted directly into a hole provided in the heat sink 26 or wrapped in a heat-resistant insulator. When carrying out this invention, the following (i)(ii)(iii)
It is also possible to implement it with improvements related to. (i) To enable measurement even when the sample gas is under pressure. As shown in FIG.
Detected in When the gas pressure is lower than atmospheric pressure, for example 10 mmH ₂ O lower than atmospheric pressure, the signal from pressure switch 37 is
Not sent to AND gate 38. Therefore, the signal from the sequence device 21 is sent to the AND gate 3.
8, no output signal from AND gate 38 occurs. However, when the pressure of the gas is higher than said pressure, the signal from the pressure switch 35 is sent to the AND gate 38, and when the signal from the sequencer 21 is sent to the AND gate 38, the output signal from the AND gate 38 is Therefore, the booster pump 39 is operated to increase the pressure of the sample gas to a measurable pressure and supply it to the sample gas inlet 1. (ii) Checking for gas leakage from the bag 7 When the sample gas is put into the bag 7, the water level on the legs 23 of the U-shaped outer body 8 rises, and the uppermost control electrode 1
0, the sequence device 21 closes the solenoid valves 4 and 5. In the case of a normal measurement operation, the state is maintained for several seconds in order to stop fluctuations in the internal pressure, and then the solenoid valve 5 is opened. However, when checking for gas leaks,
Even after several seconds have passed, the solenoid valve 5 remains closed, and thereafter the solenoid valves 4 and 5 are further closed for a predetermined period, and the solenoid valve 35 for releasing the gas leaking from the bag 7 is opened. Set up the sequence device 21 so that When the water surface leaves the uppermost control electrode 10 during the predetermined period, no signal is generated from the sequence device 21, so it can be checked that the pressure inside the bag 7 has decreased, that is, there is a gas leak. .
At the start of each measurement routine, the bag 7 is thus checked for gas leaks. (iii) To eliminate the drift phenomenon of measured values that occurs when measuring gas specific gravity over a long period of time. As shown in FIG. 6, the open upper end of the other leg 23 is hermetically sealed by a sealing member 24,
The first and second control electrodes 13, 10 and the first
The second measurement electrodes 11 and 12 are passed through the sealing member 24 in an airtight manner, and another inflatable fluid-impermeable bag 25 is inserted so that the inside thereof communicates with the inside of the other leg 23. , and airtightly attached to the sealing member 24. Alternatively, as shown in FIG. 7, the open end of a further inflatable fluid-impermeable bag 25' is hermetically mounted around the open upper end of the other leg 23, and the first and second The control electrodes 13, 10 and the first and second measurement electrodes 12, 11 are passed through the side wall of the other leg 23 in an airtight manner. In this case, the fluctuations in the outflow time Ts of the sample gas CH ₄ depending on the measurement time and the fluctuations in the measured value of specific gravity caused by the fluctuations are as follows.

[Table] As is clear from the above table, it is clear that the drift of the measured value hardly changes from 0.555 to 0.554 even during about 3 hours. On the other hand, the case of the prior art described in Japanese Patent Publication No. 59-13694 is as follows.

[Table] The sealing member 24 shown in FIG. 6 is preferably made of a rubber stopper, but can be made of any suitable synthetic rubber or synthetic resin. The size of this rubber plug is made larger than the size of the open upper end of the leg portion 23 of the U-shaped outer body 24, and the rubber plug is pushed into this upper end, and the hole provided in the rubber plug is inserted into the control electrode 10, 13. By making the electrodes smaller than the measurement electrodes 11 and 12 and pushing these electrodes into the hole, a sufficiently airtight seal can be obtained. However, a suitable sealant may be used if necessary. By gluing the open end of the bag 25 into the hole of the rubber stopper, a sufficiently airtight seal can be obtained. If the open end of the bag 25' shown in FIG. 7 is glued around the open upper end of the leg 33, airtightness can be maintained sufficiently, but a suitable sealant may be further provided around the outer periphery. A sufficiently airtight seal can be obtained by providing a suitable sealant on the side wall of the leg portion 23 through which the control electrodes 10, 13 and the measuring electrodes 11, 12 pass.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a precision gas specific gravity measuring device using the conventional outflow method described in Japanese Patent Publication No. 59-13694, and FIG. 2 is a block diagram of a precision gas specific gravity measuring device using the outflow method of the present invention. Figures 3 and 4 are explanatory diagrams of a portion of Figure 2, respectively.
7 to 7 are explanatory diagrams each showing a further improved case of a part of the precision gas specific gravity measuring device using the outflow method of the present invention. 2, 4, 5...First (first or second) and other (third) solenoid valve, 3... Constant temperature device, 6...
... Orifice plate, 7 ... Fluid-impermeable bag, 8 ... U-shaped outer body, 9 ... Water, 13, 10 ...
...First and second control electrodes, 12, 11... First and second measurement electrodes, 18... Counter, 19, 20... Arithmetic display device, 21... Sequence device, 22, 23... Leg, 26... heat sink, 27... through hole, 28... heating element, 2
9... thermistor type thermometer transmitter, 30... amplifier, 31... comparator, 32... power supply, 33... switch, 34... tube, 35... solenoid valve.

Claims (1)

[Claims] 1. (a) An inflatable fluid-impermeable bag through which gas can be introduced through a first solenoid valve, and (b) a JIS diameter bag through which gas can be discharged from this bag through another solenoid valve. a large-diameter orifice; (c) a U-shaped outer body of approximately the same diameter with water in both legs and the bag stored in one leg; and (d) the other of the legs. a first control electrode, which is arranged at a height that is successively farther away from the water surface of the bag, and which is arranged so as to be in contact with the water surface when the water surface rises and falls as the gas is introduced and discharged into the bag; (e) a device configured to measure the passing time interval when the water surface passes through the first and second measurement electrodes and descends; a counter coupled to these measuring electrodes; (f) an arithmetic display device coupled to the counter so as to compute and display the measured values of the counter; When the water level rises and descends, the other solenoid valve is closed and the most closed solenoid valve is opened; however, when the water level rises and reaches the second control electrode, the first solenoid valve is closed and the other solenoid valve is opened. In a precision gas specific gravity measurement device using an outflow method, which is equipped with these control electrodes and a sequence device coupled to the solenoid valve to open the solenoid valve, an orifice plate provided with the orifice is mounted on a heat sink, and the orifice and the solenoid valve are connected to each other. A heating element is provided to communicate with the through hole of the heat sink and to heat the heat sink, so as to keep the temperature of the heat sink constant.
A precision gas specific gravity measuring device using an outflow method, characterized in that a control means is provided for detecting the temperature of the heat sink and controlling the supply of current to the heating element. 2. (a) An inflatable, fluid-impermeable bag that allows gas to be introduced through the first solenoid valve, and (b) an orifice with a diameter larger than the JIS diameter that allows gas to be discharged from this bag through another solenoid valve. (c) a U-shaped outer body of approximately the same diameter with both legs filled with water and the bag stored in one leg; and (d) a height of the other of the legs that gradually moves away from the water surface. a first control electrode, which is disposed in a vertical position, and which is disposed so as to be in contact with the water surface when the water surface rises and falls as gas is introduced into and discharged from the bag; and first and second measurements. and a second control electrode; (f) a calculation display device connected to this counter so as to calculate and display the measured value of this counter; (g) when the water surface passes through the first control electrode and descends; , the other solenoid valve is closed and the most closed solenoid valve is opened, but when the water level rises and reaches the second control electrode, the first solenoid valve is closed and the other solenoid valve is opened. In a precision gas specific gravity measuring device using an outflow method, which is equipped with these control electrodes and a sequence device coupled to a solenoid valve, an orifice plate provided with the orifice is attached to a heat sink, and the orifice and the through hole of the heat sink are connected to each other. A heating element is provided to heat the heat sink by embedding the heat sink in a communicating state, and to keep the temperature of the heat sink constant.
A control means is provided for detecting the temperature of the heat sink and controlling the supply of current to the heating element, and one end of a tube communicating with the inside of the leg is attached to the upper end of the one leg, and An outflow method characterized in that a solenoid valve is provided between the other open end of the pipe and the one end, and the solenoid valve is connected to a sequence device 21 so as to open and close at predetermined time intervals. Precision gas specific gravity measuring device.