JPH07294467A - Continuous composition measuring method for mixed gas whose component is known, measuring pipe for continuous composition measurement and continuous composition measuring device - Google Patents

Abstract

PURPOSE:To continuously measure the composition of mixed gas whose component is known by a simple device. CONSTITUTION:A measuring pipe 2 is arranged in mixed gas supply piping 1 so as to cross a mixed gas flow, and a mixed gas inflow port 9 is arranged in the measuring pipe, and an outflow port 10 is arranged in a position separated from the inflow port, and heating elements and temperature sensing elements are alternately arranged in plural rows in the mixed gas flowing direction (f) on an inner wall reaching the outflow port from the inflow port, and a sensor part is constituted, and a part of mixed gas flowing in the supply piping is flowed in the measuring pipe from the inflow port, and is passed through the sensor part, and after a temperature rise in the mixed gas when a constant quantity of heat is added by the heating elements in the sensor part is measured by the upstream side and downstream side temperature sensing elements on plural temperature levels corresponding to the respective heating elements, it is flowed out of the outflow port, and is joined to a main flow of the mixed gas in the supply piping. A measured value by such measurement is substituted in a linear algebraic expression disclosed in a bulletin of a Patent Disclosure Heisei 4-776655 issue, and the composition is calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously measuring the composition ratio of a mixed gas, such as city gas, whose components are known, and a measuring tube used for the method.

[0002]

2. Description of the Related Art For example, in the case of city gas, it is necessary to measure the composition of the mixed gas flowing through the supply pipe in order to monitor or control the amount of heat. The conventional method for measuring the composition is as follows. It is common. An intermittent measurement method in which a part of the mixed gas is taken out from the supply pipe and introduced into the process gas chromatography device, and each component is separated by a column for measurement. A continuous measurement method in which a part of the mixed gas is taken out from the supply pipe and introduced into an infrared analyzer to measure the difference in the infrared absorption wavelength of each component. Further, as an attempt to perform continuous measurement without using the apparatus in JP-A-4-77655, there is a method disclosed in JP-A-4-77655. This method is a method to be applied when the types of components of the mixed gas are known, and the constant pressure specific heat of the mixed gas or its corresponding amount (that is, a constant amount of heat) for each temperature that is changed corresponding to the number of each component. Is a method of continuously calculating the composition by measuring the temperature difference on the upstream side and the downstream side of the mixed gas in the case of adding, and solving a linear algebraic expression representing the correspondence relationship between the constant pressure specific heat or its corresponding amount and the composition. In order to facilitate the calculation of such a composition, in this method, by connecting a plurality of measurement units for each temperature in series to configure a measurement path, and the flow rate through each measurement unit,
The amount of heat applied to each heating element is constant.

[0003]

The method of the invention is an intermittent measuring method as described above, and the measuring can be performed only in a cycle of, for example, about 2 minutes, and cannot be continuously measured. In the method (1), since a part of the mixed gas is taken out from the supply pipe as the sample gas and measured, a time delay occurs due to sampling, and a product loss corresponding to the sample gas occurs. Then, this invention aims at solving the above-mentioned subject of by applying the method of more concretely and rationally.

[0004]

In order to achieve the above-mentioned object, first, in the present invention, a measuring pipe is installed in a mixed gas supply pipe so as to traverse the flow of the mixed gas. An inlet for mixed gas is provided, an outlet is provided at a position distant from the inlet, and a plurality of heating elements and temperature measuring elements are alternately arranged in a row in the flow direction of the mixed gas on the inner wall extending from the inlet to the outlet. A part of the mixed gas flowing through the supply pipe flows into the measuring pipe from the inlet to pass through the sensor part, and a certain amount of heat is added by the heating element in the sensor part. After measuring the temperature rise of the gas with the temperature measuring elements on the upstream side and the downstream side at a plurality of temperature levels corresponding to each heating element, let it flow out from the outlet and join with the main flow of the mixed gas in the supply pipe. A composition continuous measurement method is proposed.

In the present invention, it is proposed that the heating element and the temperature measuring element are arranged in a plurality of rows in the above construction, and the composition calculated in each row is statistically processed to calculate the composition.

Further, in the present invention, in the above structure, it is proposed to provide a hot wire type flow sensor including a heating element and a temperature measuring element on the inner wall of the measuring tube from the inlet to the outlet.

In the present invention, it is proposed that the heating element and the temperature measuring element are constituted by a thin film resistor having a bridge structure in these configurations.

Further, according to the present invention, the first opening is provided in the lateral direction of the tip of the tubular body, and at a position appropriately separated from the first opening, the first opening is laterally located from the back side of the first opening. To a sensor tube fitted between the openings in the sheath tube and a second opening portion in a lateral direction at an appropriate position up to the heating element. We propose a continuous composition measuring tube, which is composed of a plurality of hot bodies arranged alternately in the axial direction to form a sensor unit.

Further, according to the present invention, the measuring pipe is installed in a mixed gas supply pipe so as to traverse the mixed gas flow. At this time, the first opening is provided on the upstream side of the mixed gas. We propose a composition continuous measuring tube with a structure installed toward the end.

[0010]

[Function] A part of the mixed gas flows into the measuring pipe installed in the supply pipe so as to traverse the mixed gas flow from the inlet on the upstream side of the flow, and after passing through the sensor section, It flows out of the outlet on the downstream side of the flow and joins again with the main flow of the mixed gas in the supply pipe.

When the mixed gas passes through the sensor section, the temperature rise of the mixed gas when a certain amount of heat is applied by the heating elements is measured at a plurality of temperature levels by the temperature measuring elements upstream and downstream of each heating element. Then, the composition is continuously calculated by solving a plurality of linear algebraic expressions showing the correspondence between the temperature difference on the upstream side and the composition.

The flow rate of the mixed gas in the sensor section necessary for calculating the composition may be estimated from the flow rate in the supply pipe, or the flow rate may be measured by forming a flow sensor in the measuring pipe.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 conceptually shows the configuration and operation of the present invention. Reference numeral 1 is a supply pipe for supplying a mixed gas such as city gas. Reference numeral 2 is a measuring pipe, and the measuring pipe 2 is installed in the supply pipe 1 so as to cross the flow of the mixed gas indicated by the arrow in the figure. That is, reference numeral 3 is a mounting pipe installed in the supply pipe, a flange portion 4 is provided at an end of the mounting pipe 3, and the flange portion 5 provided in the measuring pipe 2 is replaced with the flange portion 4.
The measuring tube 2 is installed by being held and fixed by the cover plate 6. In addition to this, the installation mechanism of the measurement tube 2 is an appropriate conventional installation mechanism for installing a sensor of an analytical instrument or a sampling tube in a pipe, for example, a sluice valve is provided in the installation pipe as an example of this installation mechanism. It is possible to use a retractor mechanism or the like in which the measuring tube can be inserted by inserting the measuring tube into the measuring tube so that the measuring tube can be replaced without lowering the pressure of the supply tube.

The measuring tube 2, as shown enlarged in FIG.
It is composed of a sheath tube 7 and a sensor tube 8 fitted therein. In FIG. 2, the sheath tube 7 is provided with a first opening 9 in the lateral direction of the tip of the can body, and at a position apart from the first opening 9 on the back side of the first opening 9. A second opening 10 is provided. The sensor tube 8 is fitted in the sheath tube 7 between the first opening 9 and the second opening 10, and the above-mentioned flange portion 5 is formed on the proximal end side of the sheath tube 7. At the same time, the lid 11 is airtightly screwed.

The measuring tube 2 is, as shown in FIG. 1 and as shown by the arrow in FIG. 2 the flow of the mixed gas,
The first opening 9 is used as a mixed gas inlet, and the second opening 10 is used.
Is installed in the supply pipe 1 so as to serve as a mixed gas outlet. That is, the first opening 9 is installed in the upstream direction of the flow of the mixed gas in the supply pipe 1.

FIG. 3 shows another example of the measuring pipe 2. The sheath pipe 7 of the measuring pipe 2 is located at a position apart from the first opening 9 and on the side of the first opening 9. A second opening 10 is provided and, as indicated by the arrows in the figure, the first
The opening 9 is provided as an inlet for the mixed gas, and the second opening 10 is provided as an outlet for the mixed gas in the supply pipe 1. The second opening 10 can be provided at an appropriate place between the places shown in FIGS. 2 and 3.

A first opening 9 is provided in the sheath tube 7 shown in FIGS.
The sensor tube 8 is fitted between the second opening 10 and the second opening 10, and the above-mentioned flange 5 is formed on the proximal end side of the sheath tube 7, and the lid 11 is hermetically screwed together. There is.

FIG. 4 conceptually shows a state in which the measuring pipe 2 of FIG. 3 is installed in the supply pipe, and the arrow f in the drawing shows the direction of the flow of the mixed gas in the supply pipe. As shown in the figure, the inflow port 9 faces the flow direction f on the upstream side, and the outflow port 10 faces the flow direction f on the downstream side.
Facing to the side.

In the example of FIG. 4, only one of the inlet port 9 and the outlet port 10 is oriented so as to form an angle with respect to the flow direction f. You can also set it up to make it.

Next, the examples of FIGS. 5 and 6 show the sensor tube 8 in an enlarged manner. As shown in these figures, the inner wall of the sensor tube 8 has five sensors depending on the number of compositions. Unit 12
Are mounted and arranged in a row in the length direction, and this row is made up of three rows.

FIGS. 7 and 8 show an enlarged example of the sensor unit 12. The sensor unit 12 is formed by anisotropically etching the semiconductor silicon substrate 13 and has three columns of thin film resistors 14a, It is configured to include 14b and 14c. This structure has recently been realized as one of the hot-wire type flow rate sensors. For use as a flow rate sensor, the sensor unit 12 is installed in a measuring tube having a predetermined inner diameter, and the thin film resistor 14b at the center is used as a heating element. , Upstream of it,
The thin film resistors 14a and 14c on the downstream side are used as temperature measuring elements. In this configuration, the thin film resistor 14b as a heating element is controlled to have a temperature higher than the ambient temperature by a control circuit incorporating an ambient temperature sensor, and a current is applied to the thin film resistor 14b so that the temperature measurement is performed in a state where heat is generated. The upstream and downstream temperatures are measured by the thin film resistors 14a and 14c as the body, the flow velocity is measured by the temperature difference between them, and the flow rate is measured from the product of the cross-sectional area of the measuring tube.

The thin film resistor 14 of the sensor unit 12 having the above-mentioned structure which is used as such a hot wire type flow sensor.
a, 14b and 14c can be used as the heating element and the temperature measuring element in the present invention. For example, as shown in FIG. 5, five sensor units 12 are arranged on the inner wall of the sensor tube 8 along the length direction to generate heat in the central thin-film resistor 14b that operates as a heating element when used as a flow sensor. The thin film resistors 14a and 14c on the upstream and downstream sides are configured as temperature measuring bodies. In this configuration, since the adjacent thin film resistors 14c and 14a of the adjacent sensor unit 12 are both operated as a temperature measuring element, either one of them can be omitted in the operation of the present invention described above. It is also possible to manufacture and use a sensor unit having various configurations. Reference numeral 15 indicates electric wires for supplying electric power to each thin film resistor 14 of each sensor unit 12 and for signal, and these electric wires 15 can be appropriately installed along the sensor tube 8. The electric wire 15 is connected to the control device 16, and the control device 16 controls energization of each thin film resistor 14 to receive a predetermined signal.

As shown in FIGS. 2 and 3, the sensor tube 8 in which the sensor units 12 are arranged on the inner wall in the above structure is mounted between the inflow port 9 and the outflow port 10 in the sheath tube 7, and the lid 1
The measurement tube 2 is constructed by tightening 1 and sealing the communication port portion through which the electric wire 15 is passed through the lid 11. Reference numeral 17 indicates an electric wire seal portion. Then, attach this measuring tube 2 to the mounting tube 3
Is inserted into the supply pipe 1 from above, and is attached as described above with the inlet 9 of the sheath pipe 7 being directed in the direction f of the flow of the mixed gas.

In this state, part of the mixed gas flowing through the supply pipe 1 flows into the measuring pipe 2 through the inflow port 9, flows through the sensor pipe 8, and then flows out through the outflow port 10 into the measuring pipe 2.
Exit and join the main flow of mixed gas again.

When the mixed gas flowing into the measuring pipe 2 flows in the sensor pipe 8, as shown schematically in FIG. 9, the sensor units 12 arranged in a row pass sequentially from the upstream side to the downstream side. At this time, in each sensor unit 12, the temperature on the inlet side of the mixed gas is measured by the thin film resistor 14a on the upstream side, and a predetermined amount of heat is added by the thin film resistor 14b on the center side to raise the temperature, and then the thin film resistor on the downstream side. 14c, the temperature of the mixed gas after adding heat is measured. The temperature of the mixed gas gradually rises as it passes through the thin film resistor 14b as a heating element of each sensor unit 12, and the temperature rises toward the downstream side. Therefore, each sensor unit 12 can measure the temperature difference between the upstream side and the downstream side of the mixed gas when a predetermined amount of heat is applied at different temperature levels. On the other hand, in one of the sensor units 12, for example, the most downstream sensor unit 12f, the thin film resistor 14b is controlled in current so that its temperature is higher than the temperature of the surrounding mixed gas by a certain temperature, and in this state The flow velocity of the mixed gas is measured by measuring the temperature difference between the upstream and downstream thin film resistors 14a and 14c, and the flow rate is measured from the product of the cross sectional area of the sensor tube 8. It should be noted that the temperature of the surrounding mixed gas is the same as that of the thin film resistor 1 on the downstream side of the sensor unit 12 adjacent to the upstream side.
4c, which can be used for the current control.

From the above measurement, the temperature difference between the upstream side and the downstream side of the mixed gas when a certain amount of heat is added for each temperature which is changed corresponding to the number of each component of the mixed gas, and the sensor tube 8 are set. The flow rate of the mixed gas passing through can be measured. Therefore, the method described in the above-mentioned Japanese Patent Application Laid-Open No. 4-77655, that is, a certain amount of heat is added to the mixed gas at each temperature which is changed according to the number of components, and the upstream and downstream are caused by this additional heat A method of measuring the temperature difference on the side and deriving the composition from each temperature difference, the flow rate of the mixed gas, the amount of additional heat, and the known constant pressure specific heat of each component at each temperature can be used.

In the above-mentioned embodiment, since three rows of five sensor units 12 are formed on the inner wall of the sensor tube 8, the above measurement or composition can be derived for each row. . 3 measured or derived in this way
A highly reliable output can be obtained by performing a statistical process such as an averaging process or a majority process on the values of the set to obtain the composition.

[0028]

As described above, the present invention has the following effects. The composition can be continuously measured. The mixed gas measured through the inside of the sensor pipe is returned to the flow inside the supply pipe, so that no sample gas that causes a loss is generated unlike the sample method. There is no time delay when passing through the sample tube in the sample system. Since the measuring pipe may be installed in a direction crossing the flow of the mixed gas in the supply pipe, the measuring pipe can be easily installed. For example, the nozzle of the existing pipe can be used.

[Brief description of drawings]

FIG. 1 is an explanatory diagram conceptually showing a configuration and an operation example of the present invention.

FIG. 2 is a vertical cross-sectional view showing a measurement tube portion of FIG. 1 in an enlarged manner.

FIG. 3 is a vertical cross-sectional view showing an enlarged measurement tube portion of another example.

FIG. 4 is a sectional view conceptually showing a state in which the measurement pipe of FIG. 2 is installed in a supply pipe.

5 is an enlarged view of the sensor tube portion of FIG. 2, Y in FIG. 6;
It is a longitudinal cross-sectional view corresponding to the -Y line portion.

6 is a transverse cross-sectional view corresponding to a portion taken along line XX of FIG.

FIG. 7 is an enlarged perspective view of a sensor unit mounted on the inner wall of the sensor tube of FIGS. 5 and 6.

8 is a vertical cross-sectional view corresponding to the ZZ line portion of FIG. 7, showing the sensor unit of FIG. 7 cut in the gas flow direction.

FIG. 9 is an explanatory diagram schematically showing elements in a row of sensor units of a sensor tube.

[Explanation of symbols]

 1 Supply Pipe 2 Measuring Pipe 3 Mounting Pipe 4, 5 Flange Part 6 Lid Plate 7 Sheath Pipe 8 Sensor Pipe 9 Opening (Inlet) 10 Opening (Outlet) 11 Lid 12 Sensor Unit 13 Silicon Substrate 14 (14a, 14a, 14b, 14c) Thin film resistance 15 Electric wire 16 Control device 17 Electric wire seal part f Direction of mixed gas flow

Claims (6)

[Claims] 1. A mixed gas supply pipe is provided with a measuring pipe so as to cross the mixed gas flow, the mixed gas inlet is provided in the measuring pipe, and an outlet is provided at a position apart from the inlet. And on the inner wall from the inlet to the outlet,
A plurality of heating elements and temperature measuring elements are alternately arranged in a row in the flow direction of the mixed gas to form the sensor unit, and a part of the mixed gas flowing through the supply pipe is made to flow from the inlet into the measuring pipe and passes through the sensor unit. Then, the temperature rise of the mixed gas when a certain amount of heat is applied by the heating element in the sensor part is measured by the temperature measuring elements on the upstream side and the downstream side at a plurality of temperature levels corresponding to each heating element, Method for continuously measuring the composition of a mixed gas of known composition, characterized in that the mixed gas is discharged from 2. The composition according to claim 1, wherein the heating element and the temperature measuring element are configured in a plurality of rows, and the composition calculated in each row is statistically processed to calculate the composition. Method for continuous measurement of mixed gas composition 3. A hot-wire type flow sensor comprising a heating element and a temperature measuring element is provided on the inner wall of the measuring tube from the inlet to the outlet, and a mixed gas of known composition according to claim 1 is provided. Composition continuous measurement method 4. The method for continuously measuring the composition of a mixed gas with known components according to claim 1, 2 or 3, wherein the heating element and the temperature measuring element are constituted by a thin film resistor having a bridge structure. 5. A first opening is provided in the lateral direction of the distal end of the tubular body, and at a position appropriately separated from the first opening,
It is composed of a sheath tube having a second opening in the lateral direction at an appropriate position from the back side to the side of the first opening, and a sensor tube fitted between the openings in the sheath tube. A measuring tube for continuously measuring the composition of a mixed gas whose components are known, characterized in that a plurality of heating elements and temperature measuring elements are alternately arranged in a row in the axial direction on the inner wall of the sensor tube to form a sensor section. 6. The measuring pipe according to claim 5, which is installed in a mixed gas supply pipe so as to cross the flow of the mixed gas, wherein the first opening is located upstream of the mixed gas. Device for continuously measuring the composition of a mixed gas of known composition characterized by being installed toward